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Sample records for heating characteristics obtained

  1. Plasticity characteristic obtained by indentation

    International Nuclear Information System (INIS)

    Mil'man, Yu.V.; Chugunova, S.I.; Goncharova, I.V.

    2011-01-01

    Methods for determination plasticity characteristic δH in the measurement of hardness and nanohardness are considered. Parameter δH characterizes the plasticity of a material by the part of plastic deformation in the total elastic-plastic deformation. The value of δH is defined for metals with different types of crystal lattice, covalent and partially covalent crystals, intermetallics, metallic glasses and quasicrystals. It is discussed the dependence of the plasticity characteristic δH on structural factors and temperature. Parameter δH allows to analyze and compare the plasticity of materials which are brittle at standard mechanical tests. The combination of hardness H, as the strength characteristic, and the plasticity characteristic δH makes possible the better characterization of mechanical behavior of materials than only the hardness H. The examples of plasticity characteristic δH application are represented.

  2. Plasticity characteristic obtained by indentation

    International Nuclear Information System (INIS)

    Milman, Yu V

    2008-01-01

    A dimensionless parameter δ H = ε p /ε t (where ε p and ε t are the average values of plastic and total deformation of material on the contact area indenter-specimen) may be used as the plasticity characteristic of materials, which made it possible to characterize the plasticity of materials that are brittle in standard mechanical tests. δ H may be calculated from the values of microhardness HM, Young's modulus E and Poisson's ratio ν. In instrumented indentation the plasticity characteristic δ A = A p /A t (A p and A t are the work of plastic and total deformation during indentation) may be calculated. δ A ∼ δ H for materials with δ H > 0.5, i.e. for all metals and the majority of ceramic materials. In this case, the theoretical equation δ A ∼ δ H = 1-10.2 · (1 - ν - 2ν 2 )(HM/E) is satisfied in experiments with the Berkovich indenter. The influence of the temperature and structural parameters (dislocation density and grain size including nanostructured materials) on δ H is discussed

  3. Heat transfer characteristics of a direct contact heat exchanger

    International Nuclear Information System (INIS)

    Kinoshita, I.; Nishi, Y.

    1993-01-01

    As a first step for development of a direct contact steam generator for FBRs, fundamental heat transfer characteristics of a liquid-liquid contact heat exchanger were evaluated by heat transfer experiment with low melting point alloy and water. Distinctive characteristics of direct contact heat transfer with liquid metal and water was obtained. (author)

  4. Heat transfer characteristics of a helical heat exchanger

    International Nuclear Information System (INIS)

    San, Jung-Yang; Hsu, Chih-Hsiang; Chen, Shih-Hao

    2012-01-01

    Heat transfer performance of a helical heat exchanger was investigated. The heat exchanger is composed of a helical tube with rectangular cross section and two cover plates. The ε–Ntu relation of the heat exchanger was obtained using a numerical method. In the analysis, the flow in the tube (helical flow) was considered to be mixed and the flow outside the tube (radial flow) was unmixed. In the experiment, the Darcy friction factor (f) and convective heat transfer coefficient (h) of the radial flow were measured. The radial flow was air and the helical flow was water. Four different channel spacing (0.5, 0.8, 1.2 and 1.6 mm) were individually considered. The Reynolds numbers were in the range 307–2547. Two correlations, one for the Darcy friction factor and the other for the Nusselt number, were proposed. - Highlights: ► We analyze the heat transfer characteristics of a helical heat exchanger and examine the effectiveness–Ntu relation. ► Increasing number of turns of the heat exchanger would slightly increase the effectiveness. ► There is an optimum Ntu value corresponding to a maximum effectiveness. ► We measure the Darcy friction factor and Nusselt number of the radial flow and examine the correlations.

  5. Transient heat transfer characteristics of liquid helium

    International Nuclear Information System (INIS)

    Tsukamoto, Osami

    1976-01-01

    The transient heat transfer characteristics of liquid helium are investigated. The critical burnout heat fluxes for pulsive heating are measured, and empirical relations between the critical burnout heat flux and the length of the heat pulse are given. The burnout is detected by observing the super-to-normal transition of the temperature sensor which is a thin lead film prepared on the heated surface by vacuum evaporation. The mechanism of boiling heat transfer for pulsive heating is discussed, and theoretical relations between the critical burnout heat flux and the length of the heat pulse are derived. The empirical data satisfy the theoretical relations fairly well. (auth.)

  6. Numerical study of heat transfer characteristics in BOG heat exchanger

    Science.gov (United States)

    Yan, Yan; Pfotenhauer, John M.; Miller, Franklin; Ni, Zhonghua; Zhi, Xiaoqin

    2016-12-01

    In this study, a numerical study of turbulent flow and the heat transfer process in a boil-off liquefied natural gas (BOG) heat exchanger was performed. Finite volume computational fluid dynamics and the k - ω based shear stress transport model were applied to simulate thermal flow of BOG and ethylene glycol in a full-sized 3D tubular heat exchanger. The simulation model has been validated and compared with the engineering specification data from its supplier. In order to investigate thermal characteristics of the heat exchanger, velocity, temperature, heat flux and thermal response were studied under different mass flowrates in the shell-side. The shell-side flow pattern is mostly determined by viscous forces, which lead to a small velocity and low temperature buffer area in the bottom-right corner of the heat exchanger. Changing the shell-side mass flowrate could result in different distributions of the shell-side flow. However, the distribution in the BOG will remain in a relatively stable pattern. Heat flux increases along with the shell-side mass flowrate, but the increase is not linear. The ratio of increased heat flux to the mass flow interval is superior at lower mass flow conditions, and the threshold mass flow for stable working conditions is defined as greater than 0.41 kg/s.

  7. Chelate forms of biometalls. Theoretical aspects of obtaining and characteristics

    Directory of Open Access Journals (Sweden)

    A. Kapustyan

    2017-04-01

    Full Text Available The problem of microelements bioavailability is highlighted and the correct ways of its solution are substantiated as a result of generalization of theoretical aspects of obtaining of the biometals chelate forms. The characteristics of the main biogenic elements, their physiological significance, electrochemical properties are presented. The main examples of the participation of biometals in various biological processes are given. The properties and the structure peculiarities of biometals coordination complexes are considered in detail. It is shown that in obtaining of biometals chelate forms, there is the mutual selectivity and the affinity of biometals and ligands. The main factors of obtaining a hard metal complex are given. Potential bioligands for obtaining bioavailable forms of microelements are detailed. Among them there are amino acids, peptides, proteins, nucleic acids, carbohydrates. The possible character of complexation depending on the nature of the bioligand is indicated. Practical examples of preparation of biometals mixed ligand complexes are given. The expediency of using metabolic products and processing of lactic acid bacteria as promising components of mixed ligand chelate complexes is substantiated. These substances contain in their composition a mass of potential donor atoms that are capable to form covalent and coordination bonds with biomethalles, and also possess high biological and immunotropic activities. The use of this system in the biocoordination compounds of the "metals of life" can provide a synergistic effect of the components, significantly to expand the range of their physiological activity and to increase the degree of assimilation by the body.

  8. Fundamental Characteristics For Building Dymanics Obtained From Microtremors Measurements.

    Science.gov (United States)

    Enomoto, T.; Abeki, N.; Kuramochi, D.; Lanuza, A.; Gonzalez, J.; Schmitz, M.; Navarro, M.

    We are performing the international joint research investigations for the seismic disaster mitigation in Metro Manila between Philippine and Japan from 1994, in Caracas between Venezuela and Japan from 1996 and also in Almeria and Granada between Spain and Japan from 1996. We have made the microtremor measurements at Reinforced Concrete (RC) buildings existed in these cities and evaluated the dynamical characteristics of RC buildings, natural period and damping factor. Even if it·fs necessary to have some discussions about the accuracy of microtremor measurement in order to evaluate the dynamical characteristics because of small amplitude range phenomena. However, the microtremor measurement method is a simple, low cost and realistic method in order to observe and investigate the actual dynamical behavior for obtaining the useful information in many countries. In these international joint research works, we settled the main object to the getting useful information of building dynamical characteristics for the seismic disaster mitigation. So, we observed microtremors at the top floor of several kinds of buildings which have the different conditions, for examples, existed place, building type, dimensional scale and number of stories etc. Then we realized the evaluation of natural period and responded damping factor of building depending on the building conditions as a statistical tendencies. In this paper, mainly we would like to present the investigated results of regression relationship between the natural period of RC building and the number of stories in Philippine and Venezuela, respectively. and also, we summarized the relationship between the natural period of RC building and damping factor considering the surrounding soil condition. We thought that these relations are reasonable and believable results in the small amplitude range evaluated from microtremors.

  9. Solar heating by radiant floor: Experimental results and emission reduction obtained with a micro photovoltaic–heat pump system

    International Nuclear Information System (INIS)

    Izquierdo, M.; Agustín-Camacho, P. de

    2015-01-01

    Highlights: • This work presents a PVT multicrystalline solar heating system for buildings. • The PV DC electricity generated was converted to AC to drive an air–water heat pump. • Experimental results obtained from December 1, 2012 to April 30, 2013 are detailed. • An environmental study is also presented. - Abstract: An experimental research with a solar photovoltaic thermal (PVT) micro grid feeding a reversible air–water, 6 kW heating capacity heat pump, has been carried out from December 2012 to April 2013. Its purpose is to heat a laboratory that is used as a house prototype for the study of heating/cooling systems. It was built in accordance with the 2013 Spanish CTE, and has an area of 35 m 2 divided into two internal rooms: one of them housing the storage system, the solar controller, the inverter and the control system; the other one is occupied by three people. Its main thermal characteristics are: UA = 125 W/°C and a maximum thermal load about 6.0 kW at the initial time. The PVT field consists of 12 modules, with a total area of 15.7 m 2 and useful area of 14 m 2 . Each module is composed of 48 polycrystalline silicon cells of 243.4 cm 2 , which with a nominal efficiency 14% can generate a power of 180 W, being the total nominal power installed 2.16 kW. The PV system stores electricity in 250 Ah batteries from where is converted from DC to AC through a 3.0 kW inverter that feeds the heat pump. This works supplying 840 l/h of hot water at 35–45 °C to the radiant floor. The data storing system is recording variables such as solar radiation; temperatures; input power to batteries; heat produced; heat transferred by the radiant floor; heat pump’s COP; isolated ratio; and solar fraction. The objective of this work is to present and discuss the experimental results and the emission reduction of CO 2 obtained during the period from 01/12/2012 to 30/04/2013, including the detailed results of two representative days of Madrid’s climate: 28

  10. Heat transfer characteristics of some oils used for engine cooling

    International Nuclear Information System (INIS)

    Abou-Ziyan, Hosny Z.

    2004-01-01

    This paper reports the results of an experimental investigation of heat transfer from a cast iron test specimen to engine oils under boiling conditions. The work is aimed at evaluating the thermal characteristics of some engine oils in contact with high temperature parts in internal combustion engines. Three mono-grade oils and two multi-grade oils are examined at heat fluxes from about 30 to more than 400 kW/m 2 for bulk temperatures of 40, 60, 80, 100, 125, 150 and 175 deg. C. The considered oils are analyzed and tested according to some ASTM standards to determine their additives concentration and to obtain some of their thermophysical properties. The results indicated that oil additives, oil properties and bulk temperatures have substantial effects on the oil characteristics. The boiling heat flux, for the best oil, rises by a factor of 1.65 as the bulk temperature decreases from 175 to 40 deg. C. The mono-grade oils produce superior heat transfer characteristics compared to those produced by multi-grade oils. The oil with the best additive concentrations produces boiling heat fluxes up to 4.44 times higher than those produced by some other oils. Comparing the results of the tested oils revealed that the oil that has the largest concentrations of boron, magnesium, phosphorus and zinc with low concentration of calcium yields the best heat transport characteristics among the other tested oils. These additives provide superior detergent and dispersant characteristics, reflected in the large alkalinity and low corrosivity of the oil. On the other side, calcium has a negative interaction with other additives and yields an adverse effect on heat transfer characteristics even when it exists in oil with large concentrations of boron, magnesium, phosphorus and zinc

  11. Periods found in heat measurements obtained by calorimetry

    International Nuclear Information System (INIS)

    Jordan, K.C.

    1984-01-01

    During a span of 640 days, a periodicity of 1.5158 +- 0.0008 days was discovered in successive heater equilibria on Calorimeter No. 127. Measurements were taken at 12-h intervals, with occasional changes of exactly 3 or 6 h in the schedule of measurements. This schedule eliminated all other possible periods except a period of 0.150156 days. Periods of 1.519125 and 1.511283 days were discovered in data on the excess length of day as obtained by the US Naval Observatory over a period of 24 y. These two periods could equally well represent periods of 0.150189 and 0.150112 days, since measurements were obtained only once every 24 h. It is suggested that periods observed in sensitive calorimeters and in length of day data may be related. 1 reference, 6 figures, 5 tables

  12. The study of the heat-engineering characteristics of a solar heat collector based on aluminum heat pipes

    International Nuclear Information System (INIS)

    Khairnasov, S.M.; Zaripov, V.K.; Passamakin, B.M. et al.

    2013-01-01

    This paper presents the results of studies into the heat-engineering characteristics of a flat heat solar collector based on aluminum heat pipes that is designed to be used in building facades. The principle of work and the structure of the solar collector are considered; the results of its comparison with a traditional flat solar collector are presented. The studies were performed at a heat carrier temperature range of +10 - +30 degree C and at a solar heat flow density of 400 - 1000 W/m 2 . The obtained experimental heat-engineering characteristics of the collector based on heat pipes show that they are at a level of traditional flow solar collectors; for example, its efficiency is 0.65 - 0.73. Meanwhile, the hydraulic resistance of the structure with heat pipes is by a factor of 2 - 2.4 smaller and ensures a high level of scalability, reliability, and maintainability, which is important when using it as an element of facade constructions of solar heat systems. (author)

  13. Heat Transfer Characteristics of SiC-coated Heat Pipe for Passive Decay Heat Removal

    International Nuclear Information System (INIS)

    Kim, Kyung Mo; Kim, In Guk; Jeong, Yeong Shin; Bang, In Cheol

    2014-01-01

    passive decay heat removal. A heat pipe was coated with SiC nanoparticles to enhance its heat removal capacity. The following results were obtained: 1. The evaporation thermal resistance of a SiC-coated heat pipe is reduced compared to that of an uncoated heat pipe because the SiC coating layer on the wick structure provides more nucleation sites. 2. The condensation thermal resistance of a SiC-coated heat pipe is increased compared to that of an uncoated heat pipe because SiC deposition results in film-wise condensation. 3. The SiC coating layer on the wick structure was observed using SEM images. The images support the reasons for the enhanced heat transfer of the SiC-coated heat pipe

  14. Heat Transfer Characteristics of SiC-coated Heat Pipe for Passive Decay Heat Removal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Kim, In Guk; Jeong, Yeong Shin; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    passive decay heat removal. A heat pipe was coated with SiC nanoparticles to enhance its heat removal capacity. The following results were obtained: 1. The evaporation thermal resistance of a SiC-coated heat pipe is reduced compared to that of an uncoated heat pipe because the SiC coating layer on the wick structure provides more nucleation sites. 2. The condensation thermal resistance of a SiC-coated heat pipe is increased compared to that of an uncoated heat pipe because SiC deposition results in film-wise condensation. 3. The SiC coating layer on the wick structure was observed using SEM images. The images support the reasons for the enhanced heat transfer of the SiC-coated heat pipe.

  15. Passive heat removal characteristics of SMART

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jae Kwang; Kang, Hyung Seok; Yoon, Joo Hyun; Kim, Hwan Yeol; Cho, Bong Hyun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A new advanced integral reactor of 330 MWt thermal capacity named SMART (System-Integrated Modular Advanced Reactor) is currently under development in Korea Atomic Energy Research Institute (KAERI) for multi-purpose applications. Modular once-through steam generator (SG) and self-pressurizing pressurizer equipped with wet thermal insulator and cooler are essential components of the SMART. The SMART provides safety systems such as Passive Residual Heat Removal System (PRHRS). In this study, a computer code for performance analysis of the PRHRS is developed by modeling relevant components and systems of the SMART. Using this computer code, a performance analysis of the PRHRS is performed in order to check whether the passive cooling concept using the PRHRS is feasible. The results of the analysis show that PRHRS of the SMART has excellent passive heat removal characteristics. 2 refs., 4 figs., 1 tab. (Author)

  16. Safety characteristics of small heat producing reactors

    International Nuclear Information System (INIS)

    Seifritz, W.

    1987-10-01

    The primary objectives of protection in nuclear power plants are the possibility to shut the reactor down in case of emergency and keep it subcritical in the long run, the existence of a heat sink for post-decay heat removal in order to avoid overheating, let alone core meltdown, and the containment of radioactivity within the barriers designed for this purpose, thus preventing significant activity release. In principle, these objectives can be met in various ways, namely by active, passive or inherent technical safeguards systems. In practice, a mixture of these approaches is employed in almost all cases. What matters in the end is the assessment of the overall concept, not of some outstanding feature. Inherent characteristics are easier to achieve in small reactors. However, also in this case, inherent safety does not mean absolute safety. If inherent safety characteristics were all encompassing, they would have to include self-healing effects. However, inanimate matter is incapable of such self-organization. Consequently, inherent characteristics in nuclear technology by definition should include the increased use of dissipative processes in the thermal part of the plant. (author)

  17. Transient Characteristics of Free Piston Vuilleurnier Cycle Heat Pumps

    Science.gov (United States)

    Matsue, Junji; Fujimoto, Norioki; Shirai, Hiroyuki

    A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed using a time-stepping integration method to investigate transient characteristics under power controlling. The nonlinear relationship between displacement and force for pistons was taken into account for the motion of reciprocating components. The force for pistons is mainly caused by the pressure change of working gas varying with piston displacements; moreover nonlinear viscous dissipative force due to the oscillating flow of working gas in heat exchangers and discontinuous damping force caused by solid friction at piston seals and rod seals are included. The displacements of pistons and pressure changes in the Vuilleumier cycle heat pump were integrated by an ideal isothermal thermodynamic relationship. It was assumed that the flow friction was proportional to the kinematic pressure of working gas, and that the solid friction at the seals was due to the functions of the working gas pressure and the tension of seal springs. In order to investigate the transient characteristics of a proposed free piston Vuilleumier cycle heat pump machine when hot-side working gas temperatures and alternate force were changed, some calculations were performed and discussed. These calculation results make clear transient characteristics at starting and power controlling. It was further found that only a small amount of starter power is required in particular conditions. During controlling, the machine becomes unstable when there is ar elatively large reduction in cooling or heating power. Therefore, an auxiliary device is additionally needed to obtain stable operation, such as al inear motor.

  18. Pressure drop and heat transfer characteristics of a high-temperature printed circuit heat exchanger

    International Nuclear Information System (INIS)

    Chen, Minghui; Sun, Xiaodong; Christensen, Richard N.; Skavdahl, Isaac; Utgikar, Vivek; Sabharwall, Piyush

    2016-01-01

    Highlights: • Pressure drop and heat transfer characteristics of a high-temperature printed circuit heat exchanger have been obtained. • Comparisons of experimental data and available correlations have been performed. • New Fanning friction factor and heat transfer correlations for the test PCHE are developed. - Abstract: Printed circuit heat exchanger (PCHE) is one of the leading intermediate heat exchanger (IHX) candidates to be employed in the very-high-temperature gas-cooled reactors (VHTRs) due to its capability for high-temperature, high-pressure applications. In the current study, a reduced-scale zigzag-channel PCHE was fabricated using Alloy 617 plates for the heat exchanger core and Alloy 800H pipes for the headers. The pressure drop and heat transfer characteristics of the PCHE were investigated experimentally in a high-temperature helium test facility (HTHF) at The Ohio State University. The PCHE helium inlet temperatures and pressures were varied up to 464 °C/2.7 MPa for the cold side and 802 °C/2.7 MPa for the hot side, respectively, while the maximum helium mass flow rates on both sides of the PCHE reached 39 kg/h. The corresponding maximum channel Reynolds number was approximately 3558, covering the laminar flow and laminar-to-turbulent flow transition regimes. New pressure drop and heat transfer correlations for the current zigzag channels with rounded bends were developed based on the experimental data. Comparisons between the experimental data and the results obtained from the available PCHE and straight circular pipe correlations were conducted. Compared to the heat transfer performance in straight circular pipes, the zigzag channels provided little advantage in the laminar flow regime but significant advantage near the transition flow regime.

  19. Possibilities of Obtaining Flat Static Characteristic of DC Ferromagnetic Actuator

    Czech Academy of Sciences Publication Activity Database

    Doležel, Ivo; Dvořák, P.; Mach, M.; Ulrych, B.

    2005-01-01

    Roč. 220, č. 1 (2005), s. 29-39 ISSN 0032-6216 R&D Projects: GA MŠk(CZ) LN00B084 Institutional research plan: CEZ:AV0Z20570509 Keywords : flat static characteristic * DC ferromagnetic actuator Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  20. Noise characteristics of neutron images obtained by cooled CCD device

    International Nuclear Information System (INIS)

    Taniguchi, Ryoichi; Sasaki, Ryoya; Okuda, Shuichi; Okamoto, Ken-Ichi; Ogawa, Yoshihiro; Tsujimoto, Tadashi

    2009-01-01

    The noise characteristics of a cooled CCD device induced by neutron and gamma ray irradiation have been investigated. In the cooled CCD images, characteristic white spot noises (CCD noise) frequently appeared, which have a shape like a pixel in most cases and their brightness is extremely high compared with that of the image pattern. They could be divided into the two groups, fixed pattern noise (FPN) and random noise. The former always appeared in the same position in the image and the latter appeared at any position. In the background image, nearly all of the CCD noises were found to be the FPN, while many of them were the random noise during the irradiation. The random CCD noises increased with irradiation and decreased soon after the irradiation. In the case of large irradiation, a part of the CCD noise remained as the FPN. These facts suggest that the CCD noise is a phenomenon strongly relating to radiation damage of the CCD device.

  1. Physicochemical characteristics of ozonated sunflower oils obtained by different procedures

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, M. F.; Sanchez, Y.; Gomez, M.; Hernandez, F.; Veloso, M. C.; Pereira, P. A.; Mangrich, A. S.; Andrade, J. B.

    2012-07-01

    Two ozonation procedures for sunflower oils at different applied ozone dosages were carried out. Ozone was obtained from medicinal oxygen and from air. Peroxide, acidity, and iodine indexes, along with density, viscosity and antimicrobial activity were determined. The fatty acid compositions of the samples were analyzed using GC. The content of oxygen was determined using an elemental analysis. Electronic Paramagnetic Resonance was used to measure the organic free radicals. The reactions were achieved up to peroxide index values of 658 and 675 mmolequiv kg1 using medicinal oxygen and air for 5 and 8 hours, respectively. The samples of ozonized sunflower oil did not present organic free radicals, which is a very important issue if these oils are to be used as drugs. The ozonation reaction is more rapid with medicinal oxygen (5 hours) than with air (8 hours). Ozonized sunflower oil with oxygen as an ozone source was obtained with high potential for antimicrobial activity. (Author) 34 refs.

  2. Evaluation of heating conditions of Ni-Zn ferrite obtained by combustion in a microwave oven

    International Nuclear Information System (INIS)

    Santos, Rafaela L.P.; Diniz, Veronica Cristhina S.; Vieira, Debora A.; Costa, Ana Cristina F.M.; Kiminam, R.H.G.A.

    2011-01-01

    This paper aims the synthesis by combustion reaction using microwave energy as heating source to obtain ferrite powders of Ni-Zn and its structural, morphological characterization. The influence of power and exposure time in the microwave oven was also investigated. The powders were prepared according to the theory of propellants and explosives using a vitreous silica crucible and urea as fuel. The powders were characterized by: XRD, BET and SEM. The resulted of XRD show only the formation of inverse spinel phase of Ni- Zn ferrite in all samples. The exposure time and power of microwave oven slightly altered the final characteristics of the powders. However, increasing the exposure time was more prominent than the increase of microwave power in both structural and morphological parameters. (author)

  3. A stydy on the heat transfer characteristics in the composite heat pipe as modeling turbine rotor

    International Nuclear Information System (INIS)

    Kwon, Sun Sok; Jang, Yeong Suc; Yoo, Byung Wook

    1993-01-01

    The purpose of this research is to study the characteristics of heat transfer in composite rotary heat pipe as modeled turbine rotating by a finite element analysis and experiment. Nu number, Re number, Pr number and dimensionless condensate layer thickness by thermal input and revolutions per minute were given as analysis factors. The comparison between calculated and experimental data showed similar tendency. Therefore the analysis method may be useful to predict the performance of composite heat pipe. The resistance on heat pipe showed the best effect of heat transfer by film condensation, by decreasing film condensation, the heat transfer rate from condenser was increased rapidly. The dimensionless condensate layer thickness according to Re number at given Pr number showed constant values, the dimensionless condensate layer thickness is proportionate to the square root of inverse of revolution number per minute. In this study Nu = A(δ(ω/ν) -1/2 Re B ) is used to the convection heat transfer coefficient and A = 0.963, B = 0.5025 were obtained as analysis predicts. (Author)

  4. Study on Heat Transfer Characteristics of One Side Heated Vertical Channel Applied as Vessel Cooling System

    International Nuclear Information System (INIS)

    Kuriyama, Shinji; Takeda, Tetsuaki; Funatani, Shumpei

    2014-01-01

    The inherent properties of the Very-High-Temperature Reactor facilitate the design of the VHTR with high degree of passive safe performances, compared to other type of reactors. However; it is still not clear if the VHTR can maintain a passive safe function during the severe accident, or what would be a design criterion to guarantee the VHTR with the high degree of passive safe performances during the accidents. In the Very High Temperature Reactor (VHTR) which is a next generation nuclear reactor system, ceramics and graphite are used as a fuel coating material and a core structural material, respectively. Even if the depressurization accident occurs and the reactor power goes up instantly, the temperature of the core will change slowly. This is because the thermal capacity of the core is so large. Therefore, the VHTR system can passively remove the decay heat of the core by natural convection and radiation from the surface of the reactor pressure vessel (RPV). This study is to develop the passive cooling system for the VHTR using the vertical channel inserting porous materials. The objective of this study is to investigate heat transfer characteristics of natural convection of a one-side heated vertical channel inserting the porous materials with high porosity. In order to obtain the heat transfer and fluid flow characteristics of a vertical channel inserting porous material, we have also carried out a numerical analysis using the commercial CFD code. From the analytical results obtained in the natural convection cooling, an amount of removed heat enhanced inserting the copper wire. It was found that an amount of removed heat inserting the copper wire (porosity = 0.9972) was about 10% higher than that without the copper wire. This paper describes a thermal performance of the one-side heated vertical channel inserting copper wire with high porosity. (author)

  5. Specific heat capacities of different clayey samples obtained by differential scanning calorimetry

    International Nuclear Information System (INIS)

    Fernandez, A.M.

    2012-01-01

    Document available in extended abstract form only. The thermo-physical properties allow to calculate heat flows and to determine the thermal behaviour of the materials. Temperature influences the rates of the physical, chemical and biological reactions and processes in the soil or a material. Variations in temperature and water content in thermal, hydraulic, mechanical and geochemical processes affect the thermal properties such as density, specific heat, thermal conductivity and thermal diffusivity. Therefore, mathematical models that describe the dependence of the thermal properties on temperature and concentration are of interest to be used in computational programs applied to the modelling of coupled thermo-mechanical-hydraulic and chemical (THMC) processes. In this work, the specific heat capacity of different clayey international reference materials was determined. Differential Scanning Calorimetry (DSC) was used for such purpose. DSC is the main tool for determining the specific heat capacities of materials as a function of temperature. The specific heat capacity, c p (J/Kg.K), is a measurement of the amount of heat required to raise the temperature of a unit mass of a substance by one unit of temperature. A change in temperature, caused by a gain or a loss of heat from a material, depends on the specific heat capacity of the material. Thus, the specific heat capacity is a key and characteristic property of a material and/or substance, which should be determine accurately. The specific heat capacity is an intensive property and, unlike the thermal conductivity and thermal diffusivity, is independent of the dry density of the material. C p of the solid samples was determined by using a SETSYS Evolution 16 thermal analyser coupled to a differential scanning calorimeter (TG-DSC-DTA) from SETARAM Instrumentation. The thermal analyser system can use a heating rate from 0.01 to 100 C/min under a dynamic argon atmosphere and temperatures ranging from ambient to

  6. Analytical and numerical treatment of the heat conduction equation obtained via time-fractional distributed-order heat conduction law

    Science.gov (United States)

    Želi, Velibor; Zorica, Dušan

    2018-02-01

    Generalization of the heat conduction equation is obtained by considering the system of equations consisting of the energy balance equation and fractional-order constitutive heat conduction law, assumed in the form of the distributed-order Cattaneo type. The Cauchy problem for system of energy balance equation and constitutive heat conduction law is treated analytically through Fourier and Laplace integral transform methods, as well as numerically by the method of finite differences through Adams-Bashforth and Grünwald-Letnikov schemes for approximation derivatives in temporal domain and leap frog scheme for spatial derivatives. Numerical examples, showing time evolution of temperature and heat flux spatial profiles, demonstrate applicability and good agreement of both methods in cases of multi-term and power-type distributed-order heat conduction laws.

  7. A study on the heat transfer characteristics of a self-oscillating heat pipe

    International Nuclear Information System (INIS)

    Yoon, Seok Hun; Oh, Cheol; Choi, Jae Hyuk

    2002-01-01

    In this paper, the heat transfer characteristics of a self-oscillating heat pipe are experimentally investigated for the effect of various working fluid fill charge ratios and heat loads. The characteristics of temperature oscillations of the working fluid are also analysed based on chaotic dynamics. The heat pipe is composed of a heating section, a cooling section and an adiabatic section, and has a 0.002m internal diameter, a 0.34m length in each turn and consists of 19 turns. The heating and the cooling portion of each turn has a length of 70mm. A series of experiments was carried out to measure the temperature distributions and the pressure variations of the heat pipe. Furthermore, heat transfer performance, effective thermal conductivity, boiling heat transfer and condensation heat transfer coefficients are calculated for various operating conditions. Experimental results show the efficacy of this type of heat pipe

  8. Visual observation of a heat pipe working characteristics

    International Nuclear Information System (INIS)

    Tsuyuzaki, Noriyoshi; Saito, Takashi; Ishigami, Shinya; Kawada, Michitaka; Konno, Masanobu; Kaminaga, Fumito; Okamoto, Yoshizo.

    1988-10-01

    When the heat pipe is used in a nuclear engineering field, it is indispensable to understand transient characteristics of an accident condition as well as in a steady state at a normal operation. However there have been few informations about the transient characteristics of a heat pipe in case of rapid temperature or heat load change in an evaporator section. The purpose of this study is to examine transient and steady state characteristics of a gravity assisted heat pipe and variable conductance heat pipe(VCHP) which will be used in a neutron irradiation capsule. This report presents results of visual observation of boiling and condensation patterns on steady state or transient condition in a visible heat pipe made of a glass. The response time of the heat pipe is on the order of a few seconds when the temperature of the evaporator part is kept above the operating temperature. (author)

  9. Some performance characteristics of a fluidized bed heat recovery unit

    International Nuclear Information System (INIS)

    Militzer, J.; Basu, P.; Adaikkappan, N.

    1985-01-01

    The advantages of using fluidized bed heat recovery units with diesel engines are well documented. Two of those are: significantly less tube fouling and heat transfer coefficient four to five time higher than that of conventional shell and tube heat exchangers. The high concentration of soot in the exhaust gases of diesel engines make fouling a major concern in design of any kind of heat recovery unit. In the experiment a conventional fluidized bed heat exchanger was connected to the exhaust of a diesel engine mounted on a dynamometer. With this arrangement it was possible to test the heat recovery unit under a wide range of operating conditions. The main objective of this experiment was the determination of the performance characteristics of the heat recovery unit, especially with reference to its heat transfer and fouling characteristics. (author)

  10. Heat transfer characteristics and limitations analysis of heat-pipe-cooled thermal protection structure

    International Nuclear Information System (INIS)

    Guangming, Xiao; Yanxia, Du; Yewei, Gui; Lei, Liu; Xiaofeng, Yang; Dong, Wei

    2014-01-01

    The theories of heat transfer, thermodynamics and fluid dynamics are employed to develop the coupled heat transfer analytical methods for the heat-pipe-cooled thermal protection structure (HPC TPS), and a three-dimensional numerical method considering the sonic limit of heat pipe is proposed. To verify the calculation correctness, computations are carried out for a typical heat pipe and the results agree well with experimental data. Then, the heat transfer characteristics and limitations of HPC TPS are mainly studied. The studies indicate that the use of heat pipe can reduce the temperature at high heat flux region of structure efficiently. However, there is a frozen startup period before the heat pipe reaching a steady operating state, and the sonic limit will be a restriction on the heat transfer capability. Thus, the effects of frozen startup must be considered for the design of HPC TPS. The simulation model and numerical method proposed in this paper can predict the heat transfer characteristics of HPC TPS quickly and exactly, and the results will provide important references for the design or performance evaluation of HPC TPS. - Highlights: • Numerical methods for the heat-pipe-cooled thermal protection structure are studied. • Three-dimensional simulation model considering sonic limit of heat pipe is proposed. • The frozen startup process of the embedded heat pipe can be predicted exactly. • Heat transfer characteristics of TPS and limitations of heat pipe are discussed

  11. Heat transfer and flow characteristics of a cooling thimble in a molten salt reactor residual heat removal system

    Directory of Open Access Journals (Sweden)

    Zonghao Yang

    2017-12-01

    Full Text Available In the passive residual heat removal system of a molten salt reactor, one of the residual heat removal methods is to use the thimble-type heat transfer elements of the drain salt tank to remove the residual heat of fuel salts. An experimental loop is designed and built with a single heat transfer element to analyze the heat transfer and flow characteristics. In this research, the influence of the size of a three-layer thimble-type heat transfer element on the heat transfer rate is analyzed. Two methods are used to obtain the heat transfer rate, and a difference of results between methods is approximately 5%. The gas gap width between the thimble and the bayonet has a large effect on the heat transfer rate. As the gas gap width increases from 1.0 mm to 11.0 mm, the heat transfer rate decreases from 5.2 kW to 1.6 kW. In addition, a natural circulation startup process is described in this paper. Finally, flashing natural circulation instability has been observed in this thimble-type heat transfer element.

  12. Heat transfer characteristics of alkali metals flowing across tube banks

    International Nuclear Information System (INIS)

    Sugiyama, K.; Ishiguro, R.; Kojima, Y.; Kanaoka, H.

    2004-01-01

    For the purpose of getting heat transfer coefficients of alkali metals flowing across tube banks at an acceptable level, we propose to use an inviscid-irrotational flow model, which is based on our flow visualization experiment. We show that the heat transfer coefficients obtained for the condition where only the test rod is heated in tube banks considerably differ from those obtained for the condition where all the rods are heated, because of interference between thick thermal boundary layers of alkali metals. We also confirm that the analytical values obtained by this flow model are in a reasonable agreement with experimental values. (author)

  13. Performance characteristics and parametric optimization of an irreversible magnetic Ericsson heat-pump

    International Nuclear Information System (INIS)

    Wei Fang; Lin Guoxing; Chen Jincan; Brueck, Ekkes

    2011-01-01

    Taking into account the finite-rate heat transfer in the heat-transfer processes, heat leak between the two external heat reservoirs, regenerative loss, regeneration time, and internal irreversibility due to dissipation of the cycle working substance, an irreversible magnetic Ericsson heat-pump cycle is presented. On the basis of the thermodynamic properties of magnetic materials, the performance characteristics of the irreversible magnetic Ericsson heat-pump are investigated and the relationship between the optimal heating load and the coefficient of performance (COP) is derived. Moreover, the maximum heating load and the corresponding COP as well as the maximum COP and the corresponding heating load are obtained. Furthermore, the other optimal performance characteristics are discussed in detail. The results obtained here may provide some new information for the optimal parameter design and the development of real magnetic Ericsson heat-pumps. -- Research Highlights: →The effects of multi-irreversibilities on the performance of a magnetic heat-pump are revealed. →Mathematical expressions of the heating load and the COP are derived and the optimal performance and operating parameters are analyzed and discussed. →Several important performance bounds are determined.

  14. Heat transfer characteristics of induced mixed convection

    International Nuclear Information System (INIS)

    Weiss, Y.; Lahav, C.; Szanto, M.; Shai, I.

    1996-01-01

    In the present work we focus our attention on the opposed Induced Mixed Convection case, i.e. the flow field structure in a vertical cylinder, closed at its bottom, opens at the top, and being heated circumferentially. The paper reports an experimental study of this complex heat transfer process. For a better understanding of the flow field and the related heat transfer process, two different experimental systems were built. The first was a flow visualization system, with water as the working fluid, while the second system enabled quantitative measurements of the temperature field in air. All the experiments were performed in the turbulent flow regime. In order to learn about all possible flow regimes, the visualization tests were conducted in three different length-to-diameter ratios (1/d=1,5,10). Quantitative measurements of the cylindrical wall temperature, as well as the radial and axial temperature profiles in the flow field, were taken in the air system. Based on the visualization observation and the measured wall temperature profile, it was found that the OIMC can be characterized by three main regimes: a mixing regime at the top, a central turbulent core and a boundary layer type of flow adjacent to the heated wall. (authors)

  15. Heat flow characteristics of Xiangshan uranium mine

    International Nuclear Information System (INIS)

    Huang Guoming

    1996-01-01

    By studying Xiangshan uranium mine on the heat generation of radioactive element, the author expounds its geothermal character and evaluates the influence on geothermal flux, geothermal gradient and geothermal field. The results show that the geothermal structure is changed due to the enrichment of radioactive elements, but the geothermal field is slightly influenced

  16. Direct contact heat transfer characteristics between melting alloy and water

    International Nuclear Information System (INIS)

    Kinoshita, Izumi; Nishi, Yoshihisa; Furuya, Masahiro

    1995-01-01

    As a candidate for an innovative steam generator for fast breeder reactors, a heat exchanger with direct contact heat transfer between melting alloy and water was proposed. The evaluation of heat transfer characteristics of this heat exchanger is one of the research subjects for the design and development of the steam generator. In this study, the effect of the pressure on heat transfer characteristics and the required degree of superheating of melting alloy above water saturation temperature are evaluated during the direct contact heat transfer experiment by injecting water into Wood's alloy. In the experiment, the pressure, the temperature of the Wood's alloy, the flow rate of feed water, and the depth of the feed water injection point are varied as parameters. As a result of the experiment, the product of the degree of Wood's alloy superheating above water saturation temperature and the depth of the feed water injection point is constant for each pressure. This constant increases as the pressure rises. (author)

  17. Nanostructures obtained from a mechanically alloyed and heat treated molybdenum carbide

    International Nuclear Information System (INIS)

    Diaz Barriga Arceo, L.; Orozco, E.; Mendoza-Leon, H.; Palacios Gonzalez, E.; Leyte Guerrero, F.; Garibay Febles, V.

    2007-01-01

    Mechanical alloying was used to prepare molybdenum carbide. Microstructural characterization of samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Molybdenum carbide was heated at 800 o C for 15 min in order to produce carbon nanotubes. Nanoparticles of about 50-140 nm in diameter and nanotubes with diameters of about 70-260 nm and 0.18-0.3 μm in length were obtained after heating at 800 o C, by means of this process

  18. Nanostructures obtained from a mechanically alloyed and heat treated molybdenum carbide

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Barriga Arceo, L. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico) and ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Orozco, E. [Instituto de Fisica UNAM, Apdo Postal 20-364, C.P. 01000 D.F. Mexico (Mexico)]. E-mail: eorozco@fisica.unam.mx; Mendoza-Leon, H. [ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Palacios Gonzalez, E. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: epalacio@imp.mx; Leyte Guerrero, F. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: fleyte@imp.mx; Garibay Febles, V. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: vgaribay@imp.mx

    2007-05-31

    Mechanical alloying was used to prepare molybdenum carbide. Microstructural characterization of samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Molybdenum carbide was heated at 800 {sup o}C for 15 min in order to produce carbon nanotubes. Nanoparticles of about 50-140 nm in diameter and nanotubes with diameters of about 70-260 nm and 0.18-0.3 {mu}m in length were obtained after heating at 800 {sup o}C, by means of this process.

  19. Heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe)

    International Nuclear Information System (INIS)

    Andros, F.E.; Florschuetz, L.W.

    1982-01-01

    Steady-state heat transfer characteristics and heat transfer limits (dry-out) for a vertical stainless steel tubular two-phase closed thermosyphon with Freon-113 working fluid are reported as a function of certain geometric parameters and liquid fill quantity. Condenser section heat transfer characteristics agreed reasonably well with existing laminar film condensation correlations and were found to be independent of the evaporator section, except for larger liquid fills. Evaporator characteristics were quite complex and appeared, under some conditions, to be coupled to condenser characteristics through effects of system pressure and/or surface wave as present on the descending condensate film. A laminar thin film evaporation model was found to give reasonable agreement with local evaporator temperature measurements in those regions of the evaporator where a continuous film apparently persisted. The measured heat transfer characteristics are interpreted relative to an earlier investigation by the authors in which flow characteristics in a similar device were visually and photographically observed. 10 references

  20. Phonon spectrum of YBCO obtained by specific heat inversion method for real data

    CERN Document Server

    Tao Wen; Dai Xian Xi; Dai Ji Xin; Evenson, W E

    2003-01-01

    In this paper, the phonon spectrum of YBCO is obtained from experimental specific heat data by an exact inversion formula with a parameter for eliminating divergences. The results can be compared to those of neutron inelastic scattering, which can only be carried out in a few laboratories. Some key points of specific heat-phonon spectrum inversion (SPI) theory and a method of asymptotic behaviour control are discussed. An improved unique existence theorem is presented, and a universal function set for numerical calculation of SPI is calculated with high accuracy, which makes the inversion method applicable and convenient in practice. This is the first time specific heat-phonon SPI has been realized for a concrete system.

  1. Start-up Characteristics of Swallow-tailed Axial-grooved Heat Pipe under the conditions of Multiple Heat Sources

    Science.gov (United States)

    Zhang, Renping

    2017-12-01

    A mathematical model was developed for predicting start-up characteristics of Swallow-tailed Axial-grooved Heat Pipe under the conditions of Multiple Heat Sources. The effects of heat capacitance of heat source, liquid-vapour interfacial evaporation-condensation heat transfer, shear stress at the interface was considered in current model. The interfacial evaporating mass flow rate is based on the kinetic analysis. Time variations of evaporating mass rate, wall temperature and liquid velocity are studied from the start-up to steady state. The calculated results show that wall temperature demonstrates step transition at the junction between the heat source and non-existent heat source on the evaporator. The liquid velocity changes drastically at the evaporator section, however, it has slight variation at the evaporator section without heat source. When the effect of heat source is ignored, the numerical temperature demonstrates a quicker response. With the consideration of capacitance of the heat source, the data obtained from the proposed model agree well with the experimental results.

  2. Heat transfer characteristics of building walls using phase change material

    Science.gov (United States)

    Irsyad, M.; Pasek, A. D.; Indartono, Y. S.; Pratomo, A. W.

    2017-03-01

    Minimizing energy consumption in air conditioning system can be done with reducing the cooling load in a room. Heat from solar radiation which passes through the wall increases the cooling load. Utilization of phase change material on walls is expected to decrease the heat rate by storing energy when the phase change process takes place. The stored energy is released when the ambient temperature is low. Temperature differences at noon and evening can be utilized as discharging and charging cycles. This study examines the characteristics of heat transfer in walls using phase change material (PCM) in the form of encapsulation and using the sleeve as well. Heat transfer of bricks containing encapsulated PCM, tested the storage and released the heat on the walls of the building models were evaluated in this study. Experiments of heat transfer on brick consist of time that is needed for heat transfer and thermal conductivity test as well. Experiments were conducted on a wall coated by PCM which was exposed on a day and night cycle to analyze the heat storage and heat release. PCM used in these experiments was coconut oil. The measured parameter is the temperature at some points in the brick, walls and ambient temperature as well. The results showed that the use of encapsulation on an empty brick can increase the time for thermal heat transfer. Thermal conductivity values of a brick containing encapsulated PCM was lower than hollow bricks, where each value was 1.3 W/m.K and 1.6 W/m.K. While the process of heat absorption takes place from 7:00 am to 06:00 pm, and the release of heat runs from 10:00 pm to 7:00 am. The use of this PCM layer can reduce the surface temperature of the walls of an average of 2°C and slows the heat into the room.

  3. Heat transfer characteristics and operation limit of pressurized hybrid heat pipe for small modular reactors

    International Nuclear Information System (INIS)

    Kim, Kyung Mo; Bang, In Cheol

    2017-01-01

    Highlights: • Thermal performances and operation limits of hybrid heat pipe were experimentally studied. • Models for predicting the operation limit of the hybrid heat pipe was developed. • Non-condensable gas affected heat transfer characteristics of the hybrid heat pipe. - Abstract: In this paper, a hybrid heat pipe is proposed for use in advanced nuclear power plants as a passive heat transfer device. The hybrid heat pipe combines the functions of a heat pipe and a control rod to simultaneously remove the decay heat generated from the core and shutdown the reactor under accident conditions. Thus, the hybrid heat pipe contains a neutron absorber in the evaporator section, which corresponds to the core of the reactor pressure vessel. The presence of the neutron absorber material leads to differences in the heated diameter and hydraulic diameter of the heat pipe. The cross-sectional areas of the vapor paths through the evaporator, adiabatic, and condenser sections are also different. The hybrid heat pipe must operate in a high-temperature, high-pressure environment to remove the decay heat. In other words, the operating pressure must be higher than those of the commercially available thermosyphons. Hence, the thermal performances, including operation limit of the hybrid heat pipe, were experimentally studied in the operating pressure range of 0.2–20 bar. The operating pressure of the hybrid heat pipe was controlled by charging the non-condensable gas which is unused method to achieve the high saturation pressure in conventional thermosyphons. The effect of operating pressure on evaporation heat transfer was negligible, while condensation heat transfer was affected by the amount of non-condensable gas in the test section. The operation limit of the hybrid heat pipe increased with the operating pressure. Maximum heat removal capacity of the hybrid heat pipe was up to 6 kW which is meaningful value as a passive decay heat removal device in the nuclear power

  4. Experimental study on local heat transfer characteristics of porous media with internal heat source

    International Nuclear Information System (INIS)

    Zan Yuanfeng; Wang Taotao; Xiao Zejun; Wang Fei; Huang Yanping

    2008-01-01

    Model of porous media with internal heat source is established. The model uses water as flowing media, and the stainless steel test section is packed with steel spheres in manner of regular triangle, respectively. The armoured resistance wire is inserted inside the steel sphere. On the basis of the experimental model, many parameters of the local heat transfer characteristics including current velocity and wall temperature of steel sphere are measured. The experimental results show that the coefficient of heat transfer scarcely changes with pressure. The coefficient of heat transfer increases with the surface heat flux of steel sphere. When raising the inlet temperature of the cooling water, the coefficient of heat transfer presents the descending trend. In addition, the influence of entrance effect on heat transfer is discovered in the experiment, which is much less than the liquid flow in the light tube. After experiment data are analyzed and processed, the relation model of heat transfer on local heat transfer characteristic of porous media with internal heat source was described with a power-law-equation. The deviations between calculation and experimental values are within ±10%. (authors)

  5. Characteristic functions of quantum heat with baths at different temperatures

    Science.gov (United States)

    Aurell, Erik

    2018-06-01

    This paper is about quantum heat defined as the change in energy of a bath during a process. The presentation takes into account recent developments in classical strong-coupling thermodynamics and addresses a version of quantum heat that satisfies quantum-classical correspondence. The characteristic function and the full counting statistics of quantum heat are shown to be formally similar. The paper further shows that the method can be extended to more than one bath, e.g., two baths at different temperatures, which opens up the prospect of studying correlations and heat flow. The paper extends earlier results on the expected quantum heat in the setting of one bath [E. Aurell and R. Eichhorn, New J. Phys. 17, 065007 (2015), 10.1088/1367-2630/17/6/065007; E. Aurell, Entropy 19, 595 (2017), 10.3390/e19110595].

  6. The characteristics of polysaccharides fractions of sunflower obtained in dynamic mode

    International Nuclear Information System (INIS)

    Makhkamov, Kh.K.; Gorshkova, R.M.; Khalikova, S.

    2013-01-01

    Present article describes characteristics of polysaccharides fractions of sunflower obtained in dynamic mode. The decomposition of sunflower pectin was studied by means of continuous fractionation method in dynamic regime. It was found that the process is of extreme nature due to heterogeneity of its macromolecule structure. The additional information on macromolecule structure of sunflower pectin was obtained.

  7. Heat transfer and flow characteristics around a finned-tube bank heat exchanger in fluidized bed

    International Nuclear Information System (INIS)

    Honda, Ryosuke; Umekawa, Hisashi; Ozawa, Mamoru

    2009-01-01

    Principal heat transfer mechanisms in a fluidized bed have been classified into three categories, i.e. solid convection, gas convection and radiation. Among these mechanisms, the solid convection is a dominant mechanism in the bubbling fluidized bed. This solid convection is substantially caused by the bubble movement, thus the visualization of the void fraction distribution becomes a very useful method to understand the characteristics of the fluidized-bed heat exchanger. In this study, the heat transfer coefficient and the void fraction around the heat transfer tube with annuler fin were measured. For the quantitative measurement of the void fraction, neutron radiography and image processing technique were employed. Owing to the existence of the annuler fin, the restriction of the particle movements was put. This restriction suppressed the disturbance caused by tubes, and the influence of the tube arrangement on the flow and heat transfer characteristics could be clearly expressed.

  8. Heat transfer and flow characteristics around a finned-tube bank heat exchanger in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Ryosuke [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Umekawa, Hisashi [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)], E-mail: umekawa@kansai-uac.jp; Ozawa, Mamoru [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2009-06-21

    Principal heat transfer mechanisms in a fluidized bed have been classified into three categories, i.e. solid convection, gas convection and radiation. Among these mechanisms, the solid convection is a dominant mechanism in the bubbling fluidized bed. This solid convection is substantially caused by the bubble movement, thus the visualization of the void fraction distribution becomes a very useful method to understand the characteristics of the fluidized-bed heat exchanger. In this study, the heat transfer coefficient and the void fraction around the heat transfer tube with annuler fin were measured. For the quantitative measurement of the void fraction, neutron radiography and image processing technique were employed. Owing to the existence of the annuler fin, the restriction of the particle movements was put. This restriction suppressed the disturbance caused by tubes, and the influence of the tube arrangement on the flow and heat transfer characteristics could be clearly expressed.

  9. Solutions obtained to international heat transfer benchmarking problems for nuclear fuel casks using Q/TRAN

    International Nuclear Information System (INIS)

    Sanchez, L.C.

    1987-02-01

    In 1985 Sandia National Laboratories participated in the Nuclear Energy Agency Committee on Reactor Physics (NEACRP) Specialists' Meeting on Heat Transfer Assessment of Transportation Packages. The objective of the meeting was to establish a set of model problems for use in comparing the performance of thermal analysis computer codes that may be used in the design of nuclear fuel shipping casks. The selected problems are to be used to compare code results for the thermal phenomena of conduction, convection, and radiation in cask-like problems. Two model problems were used in this study. The first problem required the determination of the steady-state temperatures of a 16 x 16 array of heated and unheated pins (representing fuel and control rod positions) of a simulated PWR fuel assembly. The second problem required the determination of transient temperatures of a finned surface (representing the external surface of a cask) subjected to an internal heat flux and to an external engulfing fire. Solutions to the problems were obtained with the code ''Q/TRAN.'' Solutions and descriptions of the necessary modeling techniques are given in this report

  10. Scanning electron microscopy of heat treated TiO2 nanotubes arrays obtained by anodic oxidation

    Science.gov (United States)

    Naranjo, D. I.; García-Vergara, S. J.; Blanco, S.

    2017-12-01

    Scanning electron microscopy was used to investigate the anatase-rutile transformation of self-organized TiO2 nanotubes obtained on titanium foil by anodizing and subsequent heat treatment. The anodizing was carried out at 20V in an 1% v/v HF acid and ethylene glycol:water (50:50) electrolyte at room temperature. The anodized samples were initially pre-heat treated at 450°C for 4 hours to modify the amorphous structure of TiO2 nanotubes into anatase structure. Then, the samples were heated between 600 to 800°C for different times, in order to promote the transformation to rutile structure. The formation of TiO2 nanotubes is evident by SEM images. Notably, when the samples are treated at high temperature, the formation of rutile crystals starts to become evident at the nanotubes located on the originally grain boundaries of the titanium. Thus, the anatase - rutile transformation has a close relationship with the microstructure of the titanium, more exactly with grain boundaries.

  11. Single-phase convection heat transfer characteristics of pebble-bed channels with internal heat generation

    International Nuclear Information System (INIS)

    Meng Xianke; Sun Zhongning; Xu Guangzhan

    2012-01-01

    Graphical abstract: The core of the water-cooled pebble bed reactor is the porous channels which stacked with spherical fuel elements. The gaps between the adjacent fuel elements are complex because they are stochastic and often shift. We adopt electromagnetic induction heating method to overall heat the pebble bed. By comparing and analyzing the experimental data, we get the rule of power distribution and the rule of heat transfer coefficient with particle diameter, heat flux density, inlet temperature and working fluid's Re number. Highlights: ► We adopt electromagnetic induction heating method to overall heat the pebble bed to be the internal heat source. ► The ball diameter is smaller, the effect of the heat transfer is better. ► With Re number increasing, heat transfer coefficient is also increasing and eventually tends to stabilize. ► The changing of heat power makes little effect on the heat transfer coefficient of pebble bed channels. - Abstract: The reactor core of a water-cooled pebble bed reactor includes porous channels that are formed by spherical fuel elements. This structure has notably improved heat transfer. Due to the variability and randomness of the interstices in pebble bed channels, heat transfer is complex, and there are few studies regarding this topic. To study the heat transfer characters of pebble bed channels with internal heat sources, oxidized stainless steel spheres with diameters of 3 and 8 mm and carbon steel spheres with 8 mm diameters are used in a stacked pebble bed. Distilled water is used as a refrigerant for the experiments, and the electromagnetic induction heating method is used to heat the pebble bed. By comparing and analyzing the experimental results, we obtain the governing rules for the power distribution and the heat transfer coefficient with respect to particle diameter, heat flux density, inlet temperature and working fluid Re number. From fitting of the experimental data, we obtain the dimensionless average

  12. Numerical analysis of the heat source characteristics of a two-electrode TIG arc

    International Nuclear Information System (INIS)

    Ogino, Y; Hirata, Y; Nomura, K

    2011-01-01

    Various kinds of multi-electrode welding processes are used to ensure high productivity in industrial fields such as shipbuilding, automotive manufacturing and pipe fabrication. However, it is difficult to obtain the optimum welding conditions for a specific product, because there are many operating parameters, and because welding phenomena are very complicated. In the present research, the heat source characteristics of a two-electrode TIG arc were numerically investigated using a 3D arc plasma model with a focus on the distance between the two electrodes. The arc plasma shape changed significantly, depending on the electrode spacing. The heat source characteristics, such as the heat input density and the arc pressure distribution, changed significantly when the electrode separation was varied. The maximum arc pressure of the two-electrode TIG arc was much lower than that of a single-electrode TIG. However, the total heat input of the two-electrode TIG arc was nearly constant and was independent of the electrode spacing. These heat source characteristics of the two-electrode TIG arc are useful for controlling the heat input distribution at a low arc pressure. Therefore, these results indicate the possibility of a heat source based on a two-electrode TIG arc that is capable of high heat input at low pressures.

  13. Numerical study on heat transfer characteristics of thermosyphon heat pipes using nanofluids

    International Nuclear Information System (INIS)

    Huminic, Gabriela; Huminic, Angel

    2013-01-01

    Highlights: • Numerical study of nanofluid heat transfer in thermosyphon heat pipes is performed. • Effect of nanoparticle concentration and operating temperature are studied. • Fe 2 O 3 –water nanofluid with 5.3% volume concentration shows the best performance. • Results show the improvement the thermal performances of thermosyphon heat pipe with nanofluids. - Abstract: In this work, a three-dimensional analysis is used to investigate the heat transfer of thermosyphon heat pipe using water and nanofluids as the working fluid. The study focused mainly on the effects of volume concentrations of nanoparticles and the operating temperature on the heat transfer performance of the thermosyphon heat pipe using the nanofluids. The analysis was performed for water and γ-Fe 2 O 3 nanoparticles, three volume concentrations of nanoparticles (0 vol.%, 2 vol.% and 5.3 vol.%) and four operating temperatures (60, 70, 80 and 90 °C). The numerical results show that the volume concentration of nanoparticles had a significant effect in reducing the temperature difference between the evaporator and condenser. Experimental and numerical results show qualitatively that the thermosyphon heat pipe using the nanofluid has better heat transfer characteristics than the thermosyphon heat pipe using water

  14. Study of TiO{sub 2} nanomembranes obtained by an induction heated MOCVD reactor

    Energy Technology Data Exchange (ETDEWEB)

    Crisbasan, A., E-mail: andreea.crisbasan@yahoo.com [NANOFORM Group, ICB, Université de Bourgogne, BP 47 870, 21078 Dijon (France); Chaumont, D. [NANOFORM Group, ICB, Université de Bourgogne, BP 47 870, 21078 Dijon (France); Sacilotti, M. [NANOFORM Group, ICB, Université de Bourgogne, BP 47 870, 21078 Dijon (France); Departamento de Fisica – Universidade Federal de Pernambuco, Recife (Brazil); Crisan, A.; Lazar, A.M.; Ciobanu, I. [Science and Materials Engineering Faculty, University of Transilvania, Brasov (Romania); Lacroute, Y.; Chassagnon, R. [Université de Bourgogne, BP 47 870, 21078 Dijon (France)

    2015-12-15

    Highlights: • The TiO{sub 2} structures have been obtained by the MOCVD technique using ferrocene, cobalt layer (annealed at 350 °C) and Ti(OC{sub 3}H{sub 7}){sub 4}. • The TiO{sub 2} growth at 550 °C, during 20 min on the cobalt layer (obtained by electron beam evaporation method) on soda-lime glass has as result TiO{sub 2} nanomembranes. • The TiO{sub 2} nanomembranes grow on the cobalt nuclei. • The TiO{sub 2} nanomembranes are polycrystalline, built from TiO{sub 2} anatase and rutile crystals. - Abstract: Nanostructures of TiO{sub 2} were grown using the metal oxide chemical vapor deposition (MOCVD) technique. The procedure used induction heating on a graphite susceptor. This specific feature and the use of cobalt and ferrocene catalysts resulted in nanomembranes never obtained by common MOCVD reactors. The present study discusses the preparation of TiO{sub 2} nanomembranes and the dependence of nanomembrane structure and morphology on growth parameters.

  15. Experimental study on the heat transfer characteristics in corrugated and flat plate type heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Hun; Jeong, Yong Ki; Jeon, Chung Hwan; Chang, Young June [Busan National Univ., Busan (Korea, Republic of); Lim, Hyeok [DHT, Busan (Korea, Republic of)

    2003-07-01

    An experiment was performed to study heat transfer characteristics between corrugated heat exchanger and flat plate type one. While heat capacity(13.86kW) was provided constantly and the flow speed was varied from 2.8 to 17.9m/s, the temperature and the pressure drop were measured. Furthermore, heat transfer coefficient, Colburn factor and Nusselt number were calculated using them. With increase of the flow speed for both exchangers, the coefficient and the pressure drop increased, but Colburn factor decreased. The coefficient, pressure drop and Colburn factor of the corrugated type were all higher than those of the flat one, which is due to the flow interruption with recirculation and reattachment of the corrugated type. The empirical correlations of Nusselt number were suggested for the tested two heat exchangers.

  16. Numerical Analysis for Heat Transfer Characteristics of Elliptic Fin-Tube Heat Exchanger with Various Shapes

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jae Hwan; Yoon, Jun Kyu [Gachon Univ., Seongnam (Korea, Republic of)

    2013-04-15

    In this study, the characteristics of the heat transfer coefficient and pressure drop were numerically analyzed according to the axis ratio (A R), pitch, location of vortex generator, and bump phase of the tube surface about an elliptical fin-tube heat exchanger. The boundary condition for CAD analysis was decided as a tube surface temperature of 348 K and inlet air velocity of 1.5 m/s. RCM 7th turbulent model was chosen as the numerical analysis for the sensitivity level. The analysis results indicated that the A R and transverse pitch decreased whereas the heat transfer coefficient increased. On the other hand, there was little difference in the longitudinal pitch. Furthermore, the heat transfer rate was more favorable when the vortex generator was located in front of the tube. Also, the bump phase of the tube surface indicated that the pressure drop and heat transfer were more favorable with the circle type than with the serrated type.

  17. Analysis of data obtained in two-phase flow tests of primary heat transport pumps

    International Nuclear Information System (INIS)

    Currie, T.C.

    1986-06-01

    This report analyzes data obtained in two-phase flow tests of primary heat transport pumps performed during the period 1980-1983. Phenomena which have been known to cause pump-induced flow oscillations in pressurized piping systems under two-phase conditions are reviewed and the data analyzed to determine whether any of the identified phenomena could have been responsible for the instabilities observed in those tests. Tentative explanations for the most severe instabilities are given based on those analyses. It is shown that suction pipe geometry probably plays an important role in promoting instabilities, so additional experiments to investigate the effect of suction pipe geometry on the stability of flow in a closed pipe loop under two-phase conditions are recommended

  18. Borehole heat exchangers: Longterm operational characteristics of a decentral geothermal heating system

    International Nuclear Information System (INIS)

    Rybach, L.; Eugster, W.J.; Hopkirk, R.J.; Kaelin, B.

    1992-01-01

    The heat pump-coupled borehole heat exchanger (BHE) is an efficient and small geothermal energy system for supplying heat typically to a single dwelling house. The long-term performance characteristics have been investigated by computer simulations. The numerical models were validated by measurements at instrumented BHE facilities. The results show the development of a new thermal equilibrium state after the first few years of BHE operation. The thermal influence is limited to the first few meters of the ground surrounding the BHE. The BHE could be scaled up in order to be installed in deep 'failed' holes (e.g. dry geothermal or hydrocarbon exploration holes)

  19. Effect of variable heat input on the heat transfer characteristics in an Organic Rankine Cycle system

    Directory of Open Access Journals (Sweden)

    Aboaltabooq Mahdi Hatf Kadhum

    2016-01-01

    Full Text Available This paper analyzes the heat transfer characteristics of an ORC evaporator applied on a diesel engine using measured data from experimental work such as flue gas mass flow rate and flue gas temperature. A mathematical model was developed with regard to the preheater, boiler and the superheater zones of a counter flow evaporator. Each of these zones has been subdivided into a number of cells. The hot source of the ORC cycle was modeled. The study involves the variable heat input's dependence on the ORC system's heat transfer characteristics, with especial emphasis on the evaporator. The results show that the refrigerant's heat transfer coefficient has a higher value for a 100% load from the diesel engine, and decreases with the load decrease. Also, on the exhaust gas side, the heat transfer coefficient decreases with the decrease of the load. The refrigerant's heat transfer coefficient increased normally with the evaporator's tube length in the preheater zone, and then increases rapidly in the boiler zone, followed by a decrease in the superheater zone. The exhaust gases’ heat transfer coefficient increased with the evaporator’ tube length in all zones. The results were compared with result by other authors and were found to be in agreement.

  20. Evaluation of Ultrasonic Nonlinear Characteristics in Heat-Treated Aluminum Alloy (Al-Mg-Si-Cu

    Directory of Open Access Journals (Sweden)

    JongBeom Kim

    2013-01-01

    Full Text Available The nonlinear ultrasonic technique has been known to be more sensitive to minute variation of elastic properties in material than the conventional linear ultrasonic method. In this study, the ultrasonic nonlinear characteristics in the heat-treated aluminum alloy (Al-Mg-Si-Cu have been evaluated. For this, the specimens were heat treated for various heating period up to 50 hours at three different heating temperatures: 250°C, 300°C, and 350°C. The ultrasonic nonlinear characteristics of each specimen were evaluated by measuring the ultrasonic nonlinear parameter β from the amplitudes of fundamental and second harmonic frequency components in the transmitted ultrasonic wave. After the ultrasonic test, tensile strengths and elongations were obtained by the tensile test to compare with the parameter β. The heating time showing a peak in the parameter β was identical to that showing critical change in the tensile strength and elongation, and such peak appeared at the earlier heating time in the higher heating temperature. These results suggest that the ultrasonic nonlinear parameter β can be used for monitoring the variations in elastic properties of aluminum alloys according to the heat treatment.

  1. Heat Transfer Characteristics during Boiling of Immiscible Liquids Flowing in Narrow Rectangular Heated Channels

    Directory of Open Access Journals (Sweden)

    Yasuhisa Shinmoto

    2017-11-01

    Full Text Available The use of immiscible liquids for cooling of surfaces with high heat generation density is proposed based on the experimental verification of its superior cooling characteristics in fundamental systems of pool boiling and flow boiling in a tube. For the purpose of practical applications, however, heat transfer characteristics due to flow boiling in narrow rectangular channels with different small gap sizes need to be investigated. The immiscible liquids employed here are FC72 and water, and the gap size is varied as 2, 1, and 0.5 mm between parallel rectangular plates of 30 mm × 175 mm, where one plate is heated. To evaluate the effect of gap size, the heat transfer characteristics are compared at the same inlet velocity. The generation of large flattened bubbles in a narrow gap results in two opposite trends of the heat transfer enhancement due to thin liquid film evaporation and of the deterioration due to the extension of dry patch in the liquid film. The situation is the same as that observed for pure liquids. The latter negative effect is emphasized for extremely small gap sizes if the flow rate ratio of more-volatile liquid to the total is not reduced. The addition of small flow rate of less-volatile liquid can increase the critical heat flux (CHF of pure more-volatile liquid, while the surface temperature increases at the same time and assume the values between those for more-volatile and less-volatile liquids. By the selection of small flow rate ratio of more-volatile liquid, the surface temperature of pure less-volatile liquid can be decreased without reducing high CHF inherent in the less-volatile liquid employed. The trend of heat transfer characteristics for flow boiling of immiscible mixtures in narrow channels is more sensitive to the composition compared to the flow boiling in a round tube.

  2. The study on pressure oscillation and heat transfer characteristics of oscillating capillary tube heat pipe

    International Nuclear Information System (INIS)

    Kim, Jong Soo; Bui, Ngoc Hung; Jung, Hyun Seok; Lee, Wook Hyun

    2003-01-01

    In the present study, the characteristics of pressure oscillation and heat transfer performance in an oscillating capillary tube heat pipe were experimentally investigated with respect to the heat flux, the charging ratio of working fluid, and the inclination angle to the horizontal orientation. The experimental results showed that the frequency of pressure oscillation was between 0.1 Hz and 1.5 Hz at the charging ratio of 40 vol.%. The saturation pressure of working fluid in the oscillating capillary tube heat pipe increased as the heat flux was increased. Also, as the charging ratio of working fluid was increased, the amplitude of pressure oscillation increased. When the pressure waves were symmetric sinusoidal waves at the charging ratios of 40 vol.% and 60 vol.%, the heat transfer performance was improved. At the charging ratios of 20 vol.% and 80 vol.%, the waveforms of pressure oscillation were more complicated, and the heat transfer performance reduced. At the charging ratio of 40 vol.%, the heat transfer performance of the OCHP was at the best when the inclination angle was 90 .deg., the pressure wave was a sinusoidal waveform, the pressure difference was at the least, the oscillation amplitude was at the least, and the frequency of pressure oscillation was the highest

  3. Correlation to predict heat transfer characteristics of a radially rotating heat pipe at vertical position

    Energy Technology Data Exchange (ETDEWEB)

    Waowaew, N.; Terdtoon, P.; Kamonpet, P.; Klongpanich, W. [Chiang Mai University (Thailand). Dept. of Mechanical Engineering; Maezawa, S. [Seikei University (Japan). Dept. of Mechanical Engineering

    2003-06-01

    The heat transfer characteristics of a radially rotating heat pipe (RRHP) depend on a number of parameters. This paper is a study of the effects of these parameters. They are the inner diameter of the tube, aspect ratio, rotational acceleration, working fluid and the dimensionless parameters of heat transfer. RRHPs, made of copper tubes with inner diameters of 11, 26, and 50.4 mm, were used in the experiments. The aspect ratios were 5, 10, 20 and 40 respectively. The selected working fluids were water, ethanol and R123 (CHCI{sub 2}CF{sub 3}) with a filling ratio of 60% of evaporator volume. The experiments were conducted at inclination angles of 0-90{sup o} from horizontal axis and the rotational accelerations were lower, higher and equal to gravitational acceleration. The working temperature was 90{sup o}C. The evaporator section was heated by electric power while heat in the condenser section was removed naturally by air. The evaporator and adiabatic section of the RRHP were well insulated with ceramic fibers. The experimental results showed that the heat flux decreases with an increasing inner diameter, and decreases with an increasing aspect ratio. The heat flux increases with an increasing rotational acceleration and decreases with an increasing liquid density of the working fluid. A correlation to predict the heat transfer rate at vertical position can be established. Further research will investigate a visual study of internal flow pattern and the formulation of a mathematical model. (author)

  4. Combination study of operation characteristics and heat transfer mechanism for pulsating heat pipe

    International Nuclear Information System (INIS)

    Cui, Xiaoyu; Zhu, Yue; Li, Zhihua; Shun, Shende

    2014-01-01

    Pulsating heat pipe (PHP) is becoming a promising heat transfer device for the application like electronics cooling. However, due to its complicated operation mechanism, the heat transfer properties of the PHP still have not been fully understood. This study experimentally investigated on a closed-loop PHP charged with four types of working fluids, deionized water, methanol, ethanol and acetone. Combined with the visualization experimental results from the open literature, the operation characteristics and the corresponding heat transfer mechanisms for different heat inputs (5 W up to 100 W) and different filling ratios (20% up to 95%) have been presented and elaborated. The results show that heat-transfer mechanism changed with the transition of operation patterns; before valid oscillation started, the thermal resistance was not like that described in the open literature where it decreased almost linearly, but would rather slowdown descending or even change into rise first before further decreasing (i.e. an inflection point existed); when the heat input further increased to certain level, e.g. 65 W or above, there presented a limit of heat-transfer performance which was independent of the types of working fluids and the filling ratios, but may be related to the structure, the material, the size and the inclination of the PHP. - Highlights: •The thermal mechanisms altered accordingly with the operation features in the PHP. •Unlike conventional heat pipes, continuous temperature soaring would not happen in the PHP. •Before the oscillation start-up, there existed a heat-transfer limit for the relatively stagnated flow in the PHP. •A limit of thermal performance existed in the PHP at relatively high heat inputs

  5. Modeling of rheological characteristics of the fermented dairy products obtained by novel and traditional starter cultures.

    Science.gov (United States)

    Vukić, Dajana V; Vukić, Vladimir R; Milanović, Spasenija D; Ilicić, Mirela D; Kanurić, Katarina G

    2018-06-01

    Tree different fermented dairy products obtained by conventional and non-conventional starter cultures were investigated in this paper. Textural and rheological characteristics as well as chemical composition during 21 days of storage were analysed and subsequent data processing was performed by principal component analysis. The analysis of samples` flow behaviour was focused on their time dependent properties. Parameters of Power law model described flow behaviour of samples depended on used starter culture and days of storage. The Power law model was applied successfully to describe the flow of the fermented milk, which had characteristics of shear thinning and non-Newtonian fluid behaviour.

  6. Heat transfer characteristics in a channel fitted with zigzag-cut baffles

    Energy Technology Data Exchange (ETDEWEB)

    Nuntadusit, Chayut; Waehayee, Makatar [Prince of Songkla University, Hat Yai (Thailand); Piya, Ibroheng [Princess of Naradhiwas University, Naradhiwas (Thailand); Eiamsa-ard, Smith [Mahanakorn University of Technology, Bangkok (Thailand)

    2015-06-15

    The heat transfer characteristics were experimentally investigated in a wind channel with different types of cut baffles for heat transfer augmentation. The aim of using zigzag-cut baffles is to create 3D flow structure behind the baffles instead of transverse vortex flow leading to enhance heat transfer. In this study, 4 types of baffles were examined; conventional baffle (Rectangular cross section with no cut), baffle with rectangular zigzag-cut, baffle with triangle zigzag-cut at 45 degree and at 90 degree. All of the baffles have the same height at H = 15 mm and flow blocking area. In the experiment, the row of seven baffles was attached on the inner surface of wind channel. The effects of pitch spacing length were also investigated at baffle pitch distance P/H = 4, 6 and 8 (H: Height of baffle). The experiments were performed at constant Reynolds number (Re) of 20000. The heat transfer patterns via Thermochromic liquid crystal sheet were visualized and recorded with a digital camera. The recorded images were then analyzed with image processing technique to obtain the distribution of Nusselt number. The flow characteristics pass through the baffles were also numerically studied with CFD simulation for understanding the heat transfer characteristics. The friction losses were measured to evaluate the thermal performance for each baffle. It was found that the baffle with rectangular zigzag-cut gives the best thermal performance due to heat transfer augmentation in upstream and downstream side of baffle.

  7. Thermophysical data for various transition metals at high temperatures obtained by a submicrosecond-pulse-heating method

    International Nuclear Information System (INIS)

    Seydel, U.; Bauhof, H.; Fucke, W.; Wadle, H.

    1979-01-01

    Thermophysical data for several transition metals are reported including enthalpies, electric resistivities, and specific volumes at the melting transition, and volume expansion coefficients and heat capacities in the liquid phase. Values for the critical temperatures, pressures, and volumes are given for molybdenum and tungsten. All data have been obtained by a submicrosecond-pulse-heating method. (author)

  8. Physical and textural characteristics of fermented milk products obtained by kombucha inoculums with herbal teas

    Directory of Open Access Journals (Sweden)

    Malbaša Radomir V.

    2012-01-01

    Full Text Available In this investigation, kombucha fermented milk products were produced from milk with 1.6% milk fat using 10% (v/v kombucha inoculums cultivated on the extracts of peppermint and stinging nettle. The fermentation process was conducted at temperatures of 37, 40 and 43°C. Fermentation was stopped when the pH value of 4.5 was reached. The fermentation process was shortened with an increase of temperature. Physical characteristics of the fermented products were determined by using standard methods of analysis. Textural characteristics were determined by texture profile analysis. The obtained products showed good physical and textural characteristics, typical for the yoghurt-like products. [Projekat Ministarstva nauke Republike Srbije, br. III-46009

  9. Heat transfer characteristics around a single heated rod immersed in sodium pool with gas jet injection

    International Nuclear Information System (INIS)

    Hideto Niikura; Kazuo Soga; Ken-ichiro Sugiyama; Akira Yamaguchi

    2005-01-01

    In a steam generator using liquid sodium, water intensely reacts with sodium when it leaks out from a heat transfer tube. It is important to evaluate the influence of sodium-water reaction to surrounding tubes and the shell. Hence, it has been desired to develop the simulation code for the evaluation of sodium-water reaction. From this viewpoint, the Japan Nuclear Cycle is now developing the SERAPHIM code. We reported a preliminary study to establish an experimental method for a single heated rod immersed in sodium pool with steam jet impingement planned in the near future as well as to obtain a preliminary data to verify the adequacy of SERAPHIM code. We first measured local and mean heat transfer coefficients around a horizontal single heated rod immersed in a water pool and a sodium pool with a limited volume in the experimental apparatus. It was confirmed that the mean heat transfer coefficients fairly agreed with the existing data for natural convection in water and sodium. Secondary we measured local and mean heat transfer coefficients around a horizontal single heated rod with Ar gas jet impingement immersed in the limited water pool and in the limited sodium pool. It was clearly observed that the local heat transfer coefficients in the sodium pool keep almost the same values in every angle regardless of increase in Ar gas jet velocity varied from about 8.7m/s to about 78m/s. On the other hand, it was confirmed in the water pool that local heat transfer coefficients on the forward stagnation side exposed in the Ar gas jet impingement increase with increasing the jet velocity while the local heat transfer coefficients on the opposite surface keep almost same values regardless of increase in the velocity. (authors)

  10. Structural, morphological, and thermal characterization of kraft lignin and its charcoals obtained at different heating rates

    Science.gov (United States)

    Rodrigues Brazil, Tayra; Nunes Costa, Rogeria; Massi, Marcos; Cerqueira Rezende, Mirabel

    2018-04-01

    Biomass is a renewable resource that is becoming more import due to environmental concerns and possible oil crisis. Thus, optimizing its use is a current challenge for many researchers. Lignin, which is a macromolecule with complex chemical structure, valuable physicochemical properties, and varied chemical composition, is available in large quantities in pulp and paper companies. The objective of this work is the physicochemical characterization of two Kraft lignin samples with different purities, and the study of its thermal conversion into charcoal. The lignin characterization was based on chemical, TGA, DSC, FT-IR, particle sizes, and FEG-SEM analyses. These analyses show that the lignins are mainly composed of guaiacyl and syringyl units, with residues of 30–36 wt.%, in inert atmosphere, depending on the lignin purity. From these results, the more purified lignin with higher carbon yield (%C) was selected for charcoal production. The heat treatment (HT) for carbonization of lignin, at different times (90, 180, and 420 min), resulted in different %C (41–44 wt.%). Longer HT resulted in higher %C and in charcoals with smaller pore sizes. Nanopores (∼50 nm) are observed for the charcoal obtained with the longest HT.

  11. A novel investigation of heat transfer characteristics in rifled tubes

    Science.gov (United States)

    Jegan, C. Dhayananth; Azhagesan, N.

    2018-05-01

    The experimental investigation of heat transfer of water flowing in a rifled tube was explored at different pressures and at various operating conditions in a rifled tube heat exchanger. The specifications for the inner and outer diameters of the inner tube are 25.8 and 50.6 mm, respectively. The working fluids used in shell side and tube side are cold and hot water. The rifled tube was made of the stainless steel with 4 ribs, 50.6 mm outer diameter, 0.775 mm rib height, 58o helix angle and the length 1500 mm. The effect of pressure, wall heat flux and friction factor were discussed. The results confirm that even at low pressures the rifled tubes has an obvious enhancement in heat transfer compared with smooth tube. Results depicts that the Nusselt number increases with Reynolds number and the friction factor decreases with increase in Reynolds number and the heat transfer rate is higher for the rifled tube when compared to smooth tube, because of strong swirl flow due to centrifugal action. It also confirms that, the friction factor obtained from the rifled tube is significantly higher than that of smooth tube.

  12. Investigation of Characteristics of Passive Heat Removal System Based on the Assembled Heat Transfer Tube

    Directory of Open Access Journals (Sweden)

    Xiangcheng Wu

    2016-12-01

    Full Text Available To get an insight into the operating characteristics of the passive residual heat removal system of molten salt reactors, a two-phase natural circulation test facility was constructed. The system consists of a boiling loop absorbing the heat from the drain tank, a condensing loop consuming the heat, and a steam drum. A steady-state experiment was carried out, in which the thimble temperature ranged from 450°C to 700°C and the system pressure was controlled at levels below 150 kPa. When reaching a steady state, the system was operated under saturated conditions. Some important parameters, including heat power, system resistance, and water level in the steam drum and water tank were investigated. The experimental results showed that the natural circulation system is feasible in removing the decay heat, even though some fluctuations may occur in the operation. The uneven temperature distribution in the water tank may be inevitable because convection occurs on the outside of the condensing tube besides boiling with decreasing the decay power. The instabilities in the natural circulation loop are sensitive to heat flux and system resistance rather than the water level in the steam drum and water tank. RELAP5 code shows reasonable results compared with experimental data.

  13. Investigation of characteristics of passive heat removal system based on the assembled heat transfer tube

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiang Cheng; Yan, Changqi; Meng, Zhao Ming; Chen, Kailun; Song, Shao Chuang; Yang, Zong Hao; Yu, Jie [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin (China)

    2016-12-15

    To get an insight into the operating characteristics of the passive residual heat removal system of molten salt reactors, a two-phase natural circulation test facility was constructed. The system consists of a boiling loop absorbing the heat from the drain tank, a condensing loop consuming the heat, and a steam drum. A steady-state experiment was carried out, in which the thimble temperature ranged from 450 .deg. C to 700 .deg. C and the system pressure was controlled at levels below 150 kPa. When reaching a steady state, the system was operated under saturated conditions. Some important parameters, including heat power, system resistance, and water level in the steam drum and water tank were investigated. The experimental results showed that the natural circulation system is feasible in removing the decay heat, even though some fluctuations may occur in the operation. The uneven temperature distribution in the water tank may be inevitable because convection occurs on the outside of the condensing tube besides boiling with decreasing the decay power. The instabilities in the natural circulation loop are sensitive to heat flux and system resistance rather than the water level in the steam drum and water tank. RELAP5 code shows reasonable results compared with experimental data.

  14. Differences on the effect of heat waves on mortality by sociodemographic and urban landscape characteristics.

    Science.gov (United States)

    Xu, Yihan; Dadvand, Payam; Barrera-Gómez, Jose; Sartini, Claudio; Marí-Dell'Olmo, Marc; Borrell, Carme; Medina-Ramón, Mercè; Sunyer, Jordi; Basagaña, Xavier

    2013-06-01

    Mortality increases during heat waves have been reported worldwide. The magnitude of these increases can vary within regions according to sociodemographic and urban landscape characteristics. The objectives of this study were to explore this variation and its determinants, and to identify the most heat-vulnerable areas by mapping heat vulnerability. We conducted a time-stratified case-crossover analysis using daily mortality in the Barcelona metropolitan area during the warm seasons of 1999-2006. Temperature data on the date of death were assigned to each individual, which were assigned to their census tract of residence. Eight census tract-level variables on socioeconomic or built environment characteristics were obtained from the census. Residence surrounding greenness was obtained from satellite data. The relative risk (RR) of mortality after three consecutive hot days (defined as those exceeding the 95th percentile of maximum temperature) was calculated via conditional logistic regression. Effect modification was examined by including interaction terms. Analyses were based on 52 806 deaths. The effect of three consecutive hot days was a 30% increase in all-cause mortality (RR=1.30, 95% CI 1.24 to 1.38). Heterogeneity of this effect was observed across census tracts. The effect of heat on mortality was higher in the census tracts with a large percentage of old buildings (RR=1.21, 95% CI 1.00 to 1.46), manual workers (RR=1.25, 95% CI 0.96 to 1.64) and residents perceiving little surrounding greenness (RR=1.29, 95% CI 1.01 to 1.65). After three consecutive hot days, mortality doubled in the most heat-vulnerable census tracts. Sociodemographic and urban landscape characteristics are associated to mortality risk during heat waves and are useful to build heat vulnerability maps.

  15. Experimental study on single-phase convection heat transfer characteristics of pebble bed channels with internal heat generation

    International Nuclear Information System (INIS)

    Meng Xianke; Sun Zhongning; Zhou Ping; Xu Guangzhan

    2012-01-01

    The water-cooled pebble bed reactor core is the porous channels stacked with spherical fuel elements, having evident effect on enhancing heat transfer. Owing to the variability and randomness characteristics of it's interstice, pebble bed channels have a very complex heat transfer situation and have little correlative research. In order to research the heat transfer characters of pebble bed channels with internal heat source, electromagnetic induction heating method was adopted for overall heating the pebble bed which was composed of 8 mm diameter steel balls, and the internal heat transfer characteristics were researched. By comparing and analyzing the experimental data, the rule of power distribution and heat transfer coefficient with heat flux density, inlet temperature and working fluid's Re were got. According to the experimental data fitting, the dimensionless average heat transfer coefficient correlation criteria was got. The fitting results are good agreement with the experimental results within 12% difference. (authors)

  16. An analysis of boundary-effects in obtaining the frequency dependent specific heat by effusivity measurements

    DEFF Research Database (Denmark)

    Christensen, Tage Emil; Behrens, Claus

    The frequency dependent specific heat is a significant response function characterizing the glass transition. Contrary to the dielectric response it is not easily measured over many decades. The introduction of the 3-omega method, where the temperature oscillations at a planar oscillatoric heat g...

  17. Impact of the Flameholder Heat Conductivity on Combustion Instability Characteristics

    KAUST Repository

    Hong, Seunghyuck

    2012-06-11

    In this paper, we investigate the impact of heat transfer between the flame and the flame-holder on the dynamic stability characteristics in a 50-kW backward facing step combustor. We conducted tests where we use a backward step block made of two different materials: ceramic and stainless steel whose thermal conductivities are 1.06 and 12 W/m/K, respectively. A set of experiments was conducted using a propane/air mixture at Re = 6500 for the inlet temperature of 300 - 500 K at atmospheric pressure. We measure the dynamic pressure and flame chemiluminescence to examine distinct stability characteristics using each flame-holder material over a range of operating conditions. We find that for tests with a flame-holder made of ceramic, the onset of instability is significantly delayed in time and, for certain operating conditions, disappears altogether. Stated differently, for certain operating conditions, the combustor can be stabilized by reducing the thermal conductivity of the flame-holder. As the thermal conductivity of the flame-holder increases, the combustor becomes increasingly unstable over a range of operating conditions. These results imply that the dynamic stability characteristics depend strongly on the heat transfer between the flame and the combustor wall near the flame anchoring region. Copyright © 2012 by ASME.

  18. The universal power and efficiency characteristics for irreversible reciprocating heat engine cycles

    CERN Document Server

    Qin Xiao Yong; Sun Feng Rui; Wu Chih

    2003-01-01

    The performance of irreversible reciprocating heat engine cycles with heat transfer loss and friction-like term loss is analysed using finite-time thermodynamics. The universal relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, and the optimal relation between power output and the efficiency of the cycles are derived. Moreover, analysis and optimization of the model were carried out in order to investigate the effect of cycle processes on the performance of the cycle using numerical examples. The results obtained herein include the performance characteristics of irreversible reciprocating Diesel, Otto, Atkinson and Brayton cycles.

  19. A Numerical Study on Heat Transfer and Flow Characteristics of a Finned Downhole Coaxial Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chun Dong; Lee, Dong Hyun; Park, Byung-Sik; Choi, Jaejoon [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)

    2017-02-15

    In this study, the flow and heat transfer characteristics of the finned annular passage were investigated numerically. The annular passage simulates co-axial geothermal heat exchanger, and fins are installed on its inner wall to reduce heat loss from the production passage (annulus) to injection passage (inner pipe). A commercial CFD program, Ansys Fluent, was used with SST k-ω turbulence model. The effects of the geometric parameters of the fin on the inner tube were analyzed under the periodic boundary condition. The result indicated that most parameters had a tendency to increase with an increase in the height and angle of the fin. However, it was confirmed that the Nusselt number of the inner tube on the coaxial 15, 5, 0.3 was lower than that of the smooth tube. Additionally, the Nusselt number of the inner tube exhibited a tendency of decreasing with a decrease in the spacing in Coaxial 15, S{sub f}, 0.3.

  20. Image acquisitions, processing and analysis in the process of obtaining characteristics of horse navicular bone

    Science.gov (United States)

    Zaborowicz, M.; Włodarek, J.; Przybylak, A.; Przybył, K.; Wojcieszak, D.; Czekała, W.; Ludwiczak, A.; Boniecki, P.; Koszela, K.; Przybył, J.; Skwarcz, J.

    2015-07-01

    The aim of this study was investigate the possibility of using methods of computer image analysis for the assessment and classification of morphological variability and the state of health of horse navicular bone. Assumption was that the classification based on information contained in the graphical form two-dimensional digital images of navicular bone and information of horse health. The first step in the research was define the classes of analyzed bones, and then using methods of computer image analysis for obtaining characteristics from these images. This characteristics were correlated with data concerning the animal, such as: side of hooves, number of navicular syndrome (scale 0-3), type, sex, age, weight, information about lace, information about heel. This paper shows the introduction to the study of use the neural image analysis in the diagnosis of navicular bone syndrome. Prepared method can provide an introduction to the study of non-invasive way to assess the condition of the horse navicular bone.

  1. Flow and Heat Transfer Characteristics of Turbulent Gas Flow in Microtube with Constant Heat Flux

    International Nuclear Information System (INIS)

    Hong, Chungpyo; Matsushita, Shinichi; Ueno, Ichiro; Asako, Yutaka

    2012-01-01

    Local friction factors for turbulent gas flows in circular microtubes with constant wall heat flux were obtained numerically. The numerical methodology is based on arbitrary-Lagrangian-Eulerian method to solve two-dimensional compressible momentum and energy equations. The Lam-Bremhorst's Low-Reynolds number turbulence model was employed to calculate eddy viscosity coefficient and turbulence energy. The simulations were performed for a wide flow range of Reynolds numbers and Mach numbers with different constant wall heat fluxes. The stagnation pressure was chosen in such a way that the outlet Mach number ranged from 0.07 to 1.0. Both Darcy friction factor and Fanning friction factor were locally obtained. The result shows that the obtained both friction factors were evaluated as a function of Reynolds number on the Moody chart. The values of Darcy friction factor differ from Blasius correlation due to the compressibility effects but the values of Fanning friction factor almost coincide with Blasius correlation. The wall heat flux varied from 100 to 10000 W/m 2 . The wall and bulk temperatures with positive heat flux are compared with those of incompressible flow. The result shows that the Nusselt number of turbulent gas flow is different from that of incompressible flow.

  2. Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

    Science.gov (United States)

    Liu, Feifei; Lan, Fengchong; Chen, Jiqing

    2016-07-01

    Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a ;segmented; thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed ;segmented; model shows more precise than the ;non-segmented; model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the ;segmented; model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

  3. Numerical Simulation on Subcooled Boiling Heat Transfer Characteristics of Water-Cooled W/Cu Divertors

    Science.gov (United States)

    Han, Le; Chang, Haiping; Zhang, Jingyang; Xu, Tiejun

    2015-04-01

    In order to realize safe and stable operation of a water-cooled W/Cu divertor under high heating condition, the exact knowledge of its subcooled boiling heat transfer characteristics under different design parameters is crucial. In this paper, subcooled boiling heat transfer in a water-cooled W/Cu divertor was numerically investigated based on computational fluid dynamic (CFD). The boiling heat transfer was simulated based on the Euler homogeneous phase model, and local differences of liquid physical properties were considered under one-sided high heating conditions. The calculated wall temperature was in good agreement with experimental results, with the maximum error of 5% only. On this basis, the void fraction distribution, flow field and heat transfer coefficient (HTC) distribution were obtained. The effects of heat flux, inlet velocity and inlet temperature on temperature distribution and pressure drop of a water-cooled W/Cu divertor were also investigated. These results provide a valuable reference for the thermal-hydraulic design of a water-cooled W/Cu divertor. supported by the National Magnetic Confinement Fusion Science Program of China (No. 2010GB104005), Funding of Jiangsu Innovation Program for Graduate Education (CXLX12_0170), the Fundamental Research Funds for the Central Universities of China

  4. Heat transfer and friction characteristics of rotor-assembled strand heat exchanger studied by uniform design experiment

    Directory of Open Access Journals (Sweden)

    Yan Wei

    2015-10-01

    Full Text Available The uniform distribution and experimental design is employed to study the thermo-hydraulic characteristics of a heat exchanger, which consists of the rotor-assembled strands mounted in circular smooth tubes. The uniform distribution and experimental design parameters include multiple rotor parameters such as rotor diameters, rotor lead, and height of blade, with the aim of studying their influence on the PEC, that is, ( ( Nu z / Nu g / ( f g / f z 1 / 3 , which stands for the heat transfer and friction characteristics. The best matching schemes of rotor-assembled strand, which significantly improves PEC to 2.01, are given by the regression analysis of uniform distribution and experimental design table. The single-factor experiments are performed to compare a tube installed with different kinds of rotor-assembled strands with a smooth tube without any strands when the Reynolds number changes between 20,000 and 60,000. The experimental result is in good agreement with the result obtained by the regression analysis of uniform distribution and experimental design. It is shown that the rotor diameters play important role in the heat transfer, and the optimal PEC value is obtained under the case that the rotor diameter is 21 mm. The rotor lead also contributes to the improvement of heat transfer and its optimal value is 700 mm in this study. The Nusselt number, friction factor and PEC increase with the increase in blade height. It shows that the uniform distribution and experimental design is an efficient method to find out the optimal parameters.

  5. Review of the experience obtained in the evaluation of vibrations and their effects on the structural integrity of heat exchangers

    International Nuclear Information System (INIS)

    Ghiselli, Alberto M.; Pastorini, Alberto; Kulichevsky Raul

    2000-01-01

    Flow induced vibrations may produce damage of shell-tube type heat exchangers, condensers and steam generators tubes. These vibrations could be produce by changes in the equipment operational condition or by a wrong evaluation during the design procedure. The typical results are tube damage by impact or fretting wear. This paper include a review of the flow-induced vibration mechanisms that affect shell-tube heat exchangers and some practical examples that show the results obtained evaluating this equipment. (author)

  6. Numerical investigation of heat transfer characteristic of fixed planar elastic tube bundles

    International Nuclear Information System (INIS)

    Duan, Derong; Ge, Peiqi; Bi, Wenbo

    2015-01-01

    Highlights: • Both tube-side and shell-side of planar elastic tube bundles were investigated. • Heat transfer and fluid flow were studied from the local analysis perspective. • Secondary flow varies depending on the fluid flow state and the geometry of tube. • Curvature plays a role on the external flow field. • The heat transfer of the two intermediate tube bundles is augmented. - Abstract: Planar elastic tube bundles are a novel approach to enhance heat transfer by using flow-induced vibration. This paper studied the heat transfer characteristic and fluid flow in both tube-side and shell-side using numerical simulation. Two temperature difference formulas were used to calculate convective heat transfer coefficient and the results were verified by theoretical analysis and experimental correlations. The effect of Reynolds number on overall convective heat transfer coefficient and pressure drop in tube-side and shell-side were studied. The comparison of the secondary flow in planar elastic tube bundles and conical spiral tube bundles were conducted. The external flow field and local convective heat transfer around the periphery of fixed planar elastic tube bundles subjected to the cross fluid flow were also analyzed. The results show that the energy consumption efficiency should be taken into account in the forced heat transfer process conducted by adjusting the fluid flow. The secondary flow varies depending on the fluid flow state and the geometry of tube. Hence, it is deduced that the heat transfer enhancement is obtained because the thermal boundary layer in the deformed planar elastic tube bundles caused by flow-induced vibration is damaged by the disordered secondary flow. In addition, the convective heat transfer capability of outside the two intermediate tube bundles is enhanced because of the effect of irregular and complex fluid flow affected by the role of curved tubes on both sides

  7. A Study of Heat Transfer and Flow Characteristics of Rising Taylor Bubbles

    Science.gov (United States)

    Scammell, Alexander David

    2016-01-01

    Practical application of flow boiling to ground- and space-based thermal management systems hinges on the ability to predict the systems heat removal capabilities under expected operating conditions. Research in this field has shown that the heat transfer coefficient within two-phase heat exchangers can be largely dependent on the experienced flow regime. This finding has inspired an effort to develop mechanistic heat transfer models for each flow pattern which are likely to outperform traditional empirical correlations. As a contribution to the effort, this work aimed to identify the heat transfer mechanisms for the slug flow regime through analysis of individual Taylor bubbles.An experimental apparatus was developed to inject single vapor Taylor bubbles into co-currently flowing liquid HFE 7100. The heat transfer was measured as the bubble rose through a 6 mm inner diameter heated tube using an infrared thermography technique. High-speed flow visualization was obtained and the bubble film thickness measured in an adiabatic section. Experiments were conducted at various liquid mass fluxes (43-200 kgm2s) and gravity levels (0.01g-1.8g) to characterize the effect of bubble drift velocityon the heat transfer mechanisms. Variable gravity testing was conducted during a NASA parabolic flight campaign.Results from the experiments showed that the drift velocity strongly affects the hydrodynamics and heat transfer of single elongated bubbles. At low gravity levels, bubbles exhibited shapes characteristic of capillary flows and the heat transfer enhancement due to the bubble was dominated by conduction through the thin film. At moderate to high gravity, traditional Taylor bubbles provided small values of enhancement within the film, but large peaks in the wake heat transfer occurred due to turbulent vortices induced by the film plunging into the trailing liquid slug. Characteristics of the wake heat transfer profiles were analyzed and related to the predicted velocity field

  8. Method to obtain g-functions for multiple precast quadratic pile heat exchangers

    DEFF Research Database (Denmark)

    Pagola, Maria Alberdi; Jensen, Rasmus Lund; Madsen, Søren

    The average fluid temperature circulating through the ground loop is one of the main parameters required when choosing the most adequate heat pump for a ground source heat pump installation. Besides, the analysis of the fluid temperature over time will show the sustainability of the energy supply...... over the lifetime of the installation. The average fluid temperature is subjected to the type of ground heat exchangers and the thermal interactions between them, which also depend on the soil thermal properties. For the case of precast piles, the thermal interactions become significant...... as they are usually placed within short distances (0.5 to 4 metres). Fast models that can account for these interactions are required to enable feasibility studies and support the design phase. Besides, since pile heat exchangers have a main structural role, it is also relevant to develop models that can determine...... the temperature changes that the foundation might be subjected to, to assess thermo-mechanical implications. 3D finite element model (FEM) computation of the thermal behaviour of multiple pile heat exchanger foundations is not cost effective nor for feasibility studies, nor for most design applications. Therefore...

  9. Influence of composition and rate heating on formation of black core in bodies obtained with red ceramic

    International Nuclear Information System (INIS)

    Santana, L.N.L.; Goncalves, W.P.; Silva, B.J. da; Macedo, R.S.; Santos, R.C.; Lisboa, D.

    2011-01-01

    In the heating of pieces of red pottery can the defect known as black core, this may deteriorate the technical and aesthetic characteristics of the final product. This study evaluated the influence of chemical composition and heating rate on the formation of black core in bodies red ceramic. The masses were treated and samples were extruded, dried, sintered at 900 °C, with heating rates of 5, 10, 15, 20 and 30 °C / min. and determined the following properties: water absorption, linear shrinkage and flexural strength. The pieces made with the mass containing lower content of iron oxide showed better resistance to bending when subjected to rapid heating. The presence of the black core was identified through visual analysis of the pieces after the break, being more apparent in parts subject to rates above 5 °C / min. (author)

  10. Control characteristics and heating performance analysis of automatic thermostatic valves for radiant slab heating system in residential apartments

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Byung-Cheon [Department of Building Equipment System Engineering, Kyungwon University, Seongnam City (Korea); Song, Jae-Yeob [Graduate School, Building Equipment System Engineering, Kyungwon University, Seongnam City (Korea)

    2010-04-15

    Computer simulations and experiments are carried out to research the control characteristics and heating performances for a radiant slab heating system with automatic thermostatic valves in residential apartments. An electrical equivalent R-C circuit is applied to analyze the unsteady heat transfer in the house. In addition, the radiant heat transfer between slabs, ceilings and walls in the room is evaluated by enclosure analysis method. Results of heating performance and control characteristics were determined from control methods such as automatic thermostatic valves, room air temperature-sensing method, water-temperature-sensing method, proportional control method, and On-Off control method. (author)

  11. 99Mo production using MoO3 pellets obtained by mechanical compression and heat treatment

    International Nuclear Information System (INIS)

    Rojas, Jorge; Mendoza, Pablo; Lopez, Alcides

    2014-01-01

    This paper shows the results of the MoO 3 pellets fabrication by mechanical compression and the heat treatment method (MCHT) in order to optimize the production of 99 Mo in the RACSO Nuclear Center. The effects of polyvinyl alcohol (PVA) as binder are assessed by heat treatment of pellets in air atmosphere, evaluating the elimination process with increasing temperature and solubility in 5N NaOH. The results show that the pellets fabrication technique is suitable because fulfills the required technical specifications, allows to irradiate 50 % more of 98 Mo mass and facilitate a safer radiological handling of the irradiated MoO 3 . (authors).

  12. Development, calibration and experimental results obtained with an innovative calorimeter (CALMOS) for nuclear heating measurements

    International Nuclear Information System (INIS)

    Carcreff, H.; Cloute-Cazalaa, V.; Salmon, L.

    2011-01-01

    Nuclear heating inside an MTR reactor has to be known in order to be able to control samples temperature during irradiation experiments. An R and D program has been carried out at CEA to design a new type of in-core calorimetric system. This new development, started in 2002, has for main objective to manufacture a calorimeter suitable to monitoring nuclear heating inside the 70 MWth OSIRIS material testing reactor operated by CEA's Nuclear Energy Div. at the Saclay research center. An innovative calorimetric probe, associated to a specific handling system, has been designed to provide access to measurements both along the fissile height and on the upper part of the core, where nuclear heating still remains high. Two mock-ups of the probe were manufactured and tested in 2005 and 2009 in ex-core area of OSIRIS reactor for process validation, while a displacement system has been especially studied to move the probe along a given axial measurement range. This paper deals with the development, tests on preliminary mock-ups and the finalization of the probe. Main modeling and experimental results are presented. Moreover, alternative methods to calibration for nuclear heating rate measurements which are now possible with this new calorimeter are presented and discussed. (authors)

  13. Development, calibration, and experimental results obtained with an innovative calorimeter (CALMOS) for nuclear heating measurements

    International Nuclear Information System (INIS)

    Carcreff, Hubert; Cloute-Cazalaa, Veronique; Salmon, Laurent

    2012-01-01

    Nuclear heating inside an MTR reactor has to be known in order to be able to control samples temperature during irradiation experiments. An R and D program has been carried out at CEA to design a new type of in-core calorimetric system. This new development, started in 2002, has for main objective to manufacture a calorimeter suitable to monitoring nuclear heating inside the 70 MWth OSIRIS material testing reactor operated by CEA's Nuclear Energy Division at the Saclay research center. An innovative calorimetric probe, associated to a specific handling system, has been designed to provide access to measurements both along the fissile height and on the upper part of the core, where nuclear heating still remains high. Two mock-ups of the probe were manufactured and tested in 2005 and 2009 in ex-core area of OSIRIS reactor for process validation, while a displacement system has been especially studied to move the probe along a given axial measurement range. This paper deals with the development, tests on preliminary mock-ups and the finalization of the probe. Main modeling and experimental results are presented. Moreover, alternative methods to calibration for nuclear heating rate measurements which are now possible with this new calorimeter are presented and discussed. (authors)

  14. Intramuscular Heating Characteristics of Multihour Low-Intensity Therapeutic Ultrasound.

    Science.gov (United States)

    Rigby, Justin H; Taggart, Rebecca M; Stratton, Kelly L; Lewis, George K; Draper, David O

    2015-11-01

    The heating characteristics of a stationary device delivering sustained acoustic medicine with low-intensity therapeutic ultrasound (LITUS) are unknown. To measure intramuscular (IM) heating produced by a LITUS device developed for long-duration treatment of musculoskeletal injuries. Controlled laboratory study. University research laboratory. A total of 26 healthy volunteers (16 men, 10 women; age = 23.0 ± 2.1 years, height = 1.74 ± 0.09 m, mass = 73.48 ± 14.65 kg). Participants were assigned randomly to receive active (n = 20) or placebo (n = 6) LITUS at a frequency of 3 MHz and an energy intensity of 0.132 W/cm(2) continuously for 3 hours with a single transducer or dual transducers on the triceps surae muscle. We measured IM temperature using thermocouples inserted at 1.5- and 3-cm depths into muscle. Temperatures were recorded throughout treatment and 30 minutes posttreatment. We used 2-sample t tests to determine the heating curve of the LITUS treatment and differences in final temperatures between depth and number of transducers. A mild IM temperature increase of 1 °C was reached 10 ± 5 minutes into the treatment, and a more vigorous temperature increase of 4 °C was reached 80 ± 10 minutes into the treatment. The maximal steady-state IM temperatures produced during the final 60 minutes of treatment at the 1.5-cm depth were 4.42 °C ± 0.08 °C and 3.92 °C ± 0.06 °C using 1 and 2 transducers, respectively. At the 3.0-cm depth, the maximal steady-state IM temperatures during the final 60 minutes of treatment were 3.05 °C ± 0.09 °C and 3.17 °C ± 0.05 °C using 1 and 2 transducers, respectively. We observed a difference between the temperatures measured at each depth (t78 = -2.45, P = .02), but the number of transducers used to generate heating was not different (t78 = 1.79, P = .08). The LITUS device elicited tissue heating equivalent to traditional ultrasound but could be sustained for multiple hours. It is a safe and effective alternative tool

  15. Preparation and flow characteristic of a novel phase change fluid for latent heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Deqiu [Marine College of Ningbo University, Ningbo 315211, Zhejiang (China); Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640 (China); Feng, Ziping; Xiao, Rui; Qin, Kun; Zhang, Jianjun; Song, Wenji; Tu, Qiu [Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2010-12-15

    A novel phase change emulsion (PCE) was prepared and its latent heat was measured by DSC. To analyze its feasibility in heat transportation through a piping system, an experimental system was built. The pressure drop of the PCE for turbulent flow was measured and the effects of such facts as the paraffin concentration and flow velocity were discussed. According to the pressure characteristic and latent heat of the PCE, the pumping power consumption rates of PCE to water under the same pipe diameter and a given heat transportation quantity can be obtained. The results show that mass flow rate and pumping power consumption of the PCE decrease greatly compared with water. For example, the decrease can be up to about 73% at V=0.6 m/s (20 and 30 wt%). Furthermore, the results show that PCE of 20 wt% can obtain almost the same pumping power consumption savings as PCE of 30 wt% in a certain flow velocity range. Finally, the applications of the PCE in the area of waste heat usage, electrical boiler and solar energy usage were commented. (author)

  16. Heat waves in the United States: mortality risk during heat waves and effect modification by heat wave characteristics in 43 U.S. communities.

    Science.gov (United States)

    Anderson, G Brooke; Bell, Michelle L

    2011-02-01

    Devastating health effects from recent heat waves, and projected increases in frequency, duration, and severity of heat waves from climate change, highlight the importance of understanding health consequences of heat waves. We analyzed mortality risk for heat waves in 43 U.S. cities (1987-2005) and investigated how effects relate to heat waves' intensity, duration, or timing in season. Heat waves were defined as ≥ 2 days with temperature ≥ 95th percentile for the community for 1 May through 30 September. Heat waves were characterized by their intensity, duration, and timing in season. Within each community, we estimated mortality risk during each heat wave compared with non-heat wave days, controlling for potential confounders. We combined individual heat wave effect estimates using Bayesian hierarchical modeling to generate overall effects at the community, regional, and national levels. We estimated how heat wave mortality effects were modified by heat wave characteristics (intensity, duration, timing in season). Nationally, mortality increased 3.74% [95% posterior interval (PI), 2.29-5.22%] during heat waves compared with non-heat wave days. Heat wave mortality risk increased 2.49% for every 1°F increase in heat wave intensity and 0.38% for every 1-day increase in heat wave duration. Mortality increased 5.04% (95% PI, 3.06-7.06%) during the first heat wave of the summer versus 2.65% (95% PI, 1.14-4.18%) during later heat waves, compared with non-heat wave days. Heat wave mortality impacts and effect modification by heat wave characteristics were more pronounced in the Northeast and Midwest compared with the South. We found higher mortality risk from heat waves that were more intense or longer, or those occurring earlier in summer. These findings have implications for decision makers and researchers estimating health effects from climate change.

  17. Asymmetry of characteristic X-ray peaks obtained by a Si(Li) detector

    Energy Technology Data Exchange (ETDEWEB)

    Visnovezky, Claudia [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina)], E-mail: cavy3@hotmail.com; Limandri, Silvina [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina)], E-mail: silvilimandri@hotmail.com; Canafoglia, Maria Elena [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina, Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Bonetto, Rita [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina, Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: bonetto@quimica.unlp.edu.ar; Trincavelli, Jorge [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: jorge@quechua.fis.uncor.edu

    2007-05-15

    The asymmetry of the characteristic X-ray peaks obtained using a Si(Li) detector is mainly due to incomplete charge collection. Impurities and defects in the crystalline structure of Si can act as 'traps' for holes and electrons in their trip toward the detector electrodes. Therefore, the collected charge, and consequently the detected energy, is smaller than the expected one. The global effect is that peaks may present a 'tail' toward the low energy side. This phenomenon is more important for low energies (lower than 2.3 keV, in the case of the detector characterized). In this work, the parameters related to peak asymmetry were studied, allowing a better understanding of the trapping process mentioned above. For this purpose, spectra from mono- and multi-element samples were collected for elements with atomic number between 7 and 20. In order to describe the shape of the characteristic K peaks as a function of its energy, an asymmetric correction to a Gaussian function was proposed. Spectra were obtained by electron probe microanalysis for incidence energies between 5 and 25 keV using an energy dispersive spectrometer equipped with an ultra-thin window Si(Li) detector. It was observed that the area corresponding to the asymmetric correction exhibits an energy dependence similar to that of the mass absorption coefficient of the detector material. In addition, other two spectrometers were used to investigate the dependence of tailing on the detection system. When two spectrometers with the same kind of detector and different pulse processors were compared, peaks were more asymmetric for lower peaking time values. When two different detectors were used, differences were even more important.

  18. Investigation on heat transfer characteristics and flow performance of Methane at supercritical pressures

    Science.gov (United States)

    Xian, Hong Wei; Oumer, A. N.; Basrawi, F.; Mamat, Rizalman; Abdullah, A. A.

    2018-04-01

    The aim of this study is to investigate the heat transfer and flow characteristic of cryogenic methane in regenerative cooling system at supercritical pressures. The thermo-physical properties of supercritical methane were obtained from the National institute of Standards and Technology (NIST) webbook. The numerical model was developed based on the assumptions of steady, turbulent and Newtonian flow. For mesh independence test and model validation, the simulation results were compared with published experimental results. The effect of four different performance parameter ranges namely inlet pressure (5 to 8 MPa), inlet temperature (120 to 150 K), heat flux (2 to 5 MW/m2) and mass flux (7000 to 15000 kg/m2s) on heat transfer and flow performances were investigated. It was found that the simulation results showed good agreement with experimental data with maximum deviation of 10 % which indicates the validity of the developed model. At low inlet temperature, the change of specific heat capacity at near-wall region along the tube length was not significant while the pressure drop registered was high. However, significant variation was observed for the case of higher inlet temperature. It was also observed that the heat transfer performance and pressure drop penalty increased when the mass flux was increased. Regarding the effect of inlet pressure, the heat transfer performance and pressure drop results decreased when the inlet pressure is increased.

  19. Devolatilization characteristics of biomass at flash heating rate

    Energy Technology Data Exchange (ETDEWEB)

    Xiu Shuangning; Li Zhihe; Li Baoming; Yi Weiming; Bai Xueyuan [China Agricultural University, Beijing (China). College of Water Conservancy and Civil Engineering

    2006-03-15

    The devolatilization characteristics of biomass (wheat straw, coconut shell, rice husk and cotton stalk) during flash pyrolysis has been investigated on a plasma heated laminar entrained flow reactor (PHLEFR) with average heating rates of 10{sup 4} K/s. These experiments were conducted with steady temperatures between 750 and 900 K, and the particle residence time varied from about 0.115 to 0.240 s. The ash tracer method was introduced to calculate the yield of volatile products at a set temperature and the residence time. This experimental study showed that the yield of volatile products depends both on the final pyrolysis temperature and the residence time. From the results, a comparative analysis was done for the biomasses, and a one-step global model was used to simulate the flash pyrolytic process and predict the yield of volatile products during pyrolysis. The corresponding kinetic parameters of the biomasses were also analyzed and determined. These results were essential for designing a suitable pyrolysis reactor. 24 refs., 5 figs., 5 tabs.

  20. Pyrolysis Characteristics of Corn Stalk with Solid Heat Carrier

    Directory of Open Access Journals (Sweden)

    Min Guo

    2015-05-01

    Full Text Available Pyrolysis of corn stalk with a solid heat carrier was studied under temperatures ranging from 430 to 620 °C. The solid heat carrier used was high-temperature ash from a CFB boiler. The yields of three products and their characteristics were investigated. Moreover, the distributions of sulfur and nitrogen in the products were determined. The results indicate that with increasing temperature, the char yield decreased, gas yield increased, and calorific value of the gas increased from 10.13 to 16.65 MJ/m3. The yield of bio-oil reached a maximum, 14.24 wt.%, at 510 °C. Light-oil in the bio-oil accounted for more than 69.12 wt.%. The elemental composition of the char and char ash were analyzed. The distribution of sulfur and nitrogen in the char decreased to 60.44 and 46.52 wt.%, respectively, depending on the raw materials used. These results provide basic data for the possible industrial application of corn stalk.

  1. Denaturation and in Vitro Gastric Digestion of Heat-Treated Quinoa Protein Isolates Obtained at Various Extraction pH

    NARCIS (Netherlands)

    Ruiz, Geraldine Avila; Opazo-Navarrete, Mauricio; Meurs, Marlon; Minor, Marcel; Sala, Guido; Boekel, van Tiny; Stieger, Markus; Janssen, Anja E.M.

    2016-01-01

    The aim of this study was to determine the influence of heat processing on denaturation and digestibility properties of protein isolates obtained from sweet quinoa (Chenopodium quinoa Willd) at various extraction pH values (8, 9, 10 and 11). Pretreatment of suspensions of protein isolates at 60,

  2. Numerical Investigation of the Main Characteristics of Heat and Mass Transfer while Heating the Heterogeneous Water Droplet in the Hot Gases

    Directory of Open Access Journals (Sweden)

    Piskunov Maxim V.

    2016-01-01

    Full Text Available The processes of heat and evaporation of heterogeneous water droplet with solid (by the example of carbon inclusion in hot (from 800 K to 1500 K gases were investigated by the developed models of heat and mass transfer. We defined the limited conditions, characteristics of the droplet and the gas medium which are sufficient for implementing the “explosive” destruction of heterogeneous droplet due to intensive vaporization on an inner interface, and intensive evaporation of liquid from an external (free droplet surface. The values of the main characteristic of the process (period from start of heating to “explosive” destruction obtained in response to using various heat and mass transfer models were compared.

  3. A numerical analysis on the heat transfer and pressure drop characteristics of welding type plate heat exchangers

    International Nuclear Information System (INIS)

    Jeong, Jong Yun; Kang, Yong Tae; Nam, Sang Chul

    2008-01-01

    Numerical analysis was carried out to examine the heat transfer and pressure drop characteristics of plate heat exchangers for absorption application using computational Fluid Dynamics(CFD) technique. A commercial CFD software package, FLUENT was used to predict the characteristics of heat transfer, pressure drop and flow distribution within plate heat exchangers. In this paper, a welded plate heat exchanger with the plate of chevron embossing type was numerically analyzed by controlling mass flow rate, solution concentration, and inlet temperatures. The working fluid is H 2 O/LiBr solution with the LiBr concentration of 50∼60% in mass. The numerical simulation show reasonably good agreement with the experimental results. Also, the numerical results show that plate of the chevron shape gives better results than plate of the elliptical shape from the view points of heat transfer and pressure drop. These results provide a guideline to apply the welded PHE for the solution heat exchanger of absorption systems

  4. Theoretical estimation of adiabatic temperature rise from the heat flow data obtained from a reaction calorimeter

    International Nuclear Information System (INIS)

    Das, Parichay K.

    2012-01-01

    Highlights: ► This method for estimating ΔT ad (t) against time in a semi-batch reactor is distinctively pioneer and novel. ► It has established uniquely a direct correspondence between the evolution of ΔT ad (t) in RC and C A (t) in a semi-batch reactor. ► Through a unique reaction scheme, the independent effects of heat of mixing and reaction on ΔT ad (t) has been demonstrated quantitatively. ► This work will help to build a thermally safe corridor of a thermally hazard reaction. ► This manuscript, the author believes will open a new vista for further research in Adiabatic Calorimetry. - Abstract: A novel method for estimating the transient profile of adiabatic rise in temperature has been developed from the heat flow data for exothermic chemical reactions that are conducted in reaction calorimeter (RC). It has also been mathematically demonstrated by the present design that there exists a direct qualitative equivalence between the temporal evolution of the adiabatic temperature rise and the concentration of the limiting reactant for an exothermic chemical reaction, carried out in semi batch mode. The proposed procedure shows that the adiabatic temperature rise will always be less than that of the reaction executed at batch mode thereby affording a thermally safe corridor. Moreover, a unique reaction scheme has been designed to establish the independent heat effect of dissolution and reaction quantitatively. It is hoped that the testimony of the transient adiabatic temperature rise that can be prepared by the proposed method, may provide ample scope for further research.

  5. Electron and phonon properties of 25 A-15 superconductors obtained from heat capacity measurements

    International Nuclear Information System (INIS)

    Junod, A.

    1982-01-01

    We review 25 specific heat measurements performed in Geneva on binary and pseudo-binary A-15 compounds. The rather extended temperature range allows us to make reliable estimates of several moments of the phonon spectrum which are required in the theory of superconductivity. The Tsub(c) expression of Allen and Dynes can then be used consistently to estimate the microscopic parameters lambda, eta, Nsub(bs) (Esub(F)), etc. The broad range of values reviewed permits to establish significant correlations between the parameters in stoichiometric and ordered compounds. (orig.)

  6. Physical properties and component contents of brown coal tars obtained in semicoking with a solid heat transfer semicoke

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, V I; Bobrova, A A

    1955-01-01

    Tar obtained in low-temperature carbonization of brown coals with brown-coal semicoke as a heat-transfer medium contains more water and dust, has a lower drop point, and a higher specific gravity, and contains more asphaltene and less paraffin than does tar from the same coal produced in rotating retorts or in shaft kilns. The brown-coal semicoke used as a heat-transfer medium produces partial thermal cracking of the fuel and polymerization of the products of secondary decompositions. The yield of asphaltenes is lowered when the carbonization temperature is raised.

  7. Influence of nitric acid concentration on the characteristics of active carbons obtained from a mineral coal

    Energy Technology Data Exchange (ETDEWEB)

    Khelifi, A.; Temdrara, L.; Addoun, A. [Laboratoire d' Etude Physicochimique des Materiaux et Application a l' Environnement, Faculte de Chimie, USTHB, BP. 32 El Alia, Bab Ezzouar 16111, Algiers (Algeria); Almazan-Almazan, M.C.; Perez-Mendoza, M.; Domingo-Garcia, M.; Lopez-Garzon, F.J [Departamento de Quimica Inorganica, Facultad de Ciencias, 18071 Granada (Spain); Lopez-Domingo, F.J. [Departamento de CCIA, ETS de Ingenieria Informatica y Telecomunicacion, Granada, 18071 (Spain)

    2010-10-15

    This paper deals with the effect of the concentration of nitric acid solutions on the properties of activated carbons obtained by the oxidation of a parent activated carbon. For this purpose a mineral coal from Algeria has been used as raw material to prepare the parent active carbon AC. This was further treated with nitric acid solutions. The analysis of the samples includes the chemical and textural characterization. The former was carried out by selective titrations and FTIR spectroscopy. The latter, by nitrogen and carbon dioxide adsorption at 77 and 273 K, respectively, and by adsorption of organic probes (benzene, dichloromethane, cyclohexane and 2,2-dimethyl butane) at 303 K. The nitrogen adsorption isotherms have been analysed by using the BET equation, {alpha}{sub s}-method and molecular simulation. The Dubinin-Radushkevich approach has been applied to the carbon dioxide and vapours adsorption data. The results show that the treatment with 2 N nitric acid solution is very appropriate because it introduces a large amount of oxygen containing groups with a small change of the textural characteristics of the parent AC. More concentrated nitric acid solutions change in large extent the textural properties although they also introduce large amount of chemical groups. (author)

  8. Experimental results obtained with the simulated cold moderator system. System characteristics and technical issues

    CERN Document Server

    Aso, T; Hino, R; Kaminaga, M; Kinoshita, H; Takahashi, T

    2002-01-01

    The Japan Atomic Energy Research Institute and the High Energy Accelerator Research Organization have been developing a Mega-Watt scale spallation target system. In the system, neutrons generated in a target are sorted out their energy to the proper values in liquid-hydrogen moderators. Then, the liquid-hydrogen is forced to circulate in order to suppress hydrogen temperature increase. In the operation of moderators, it is very important to establish a safety protection system against emergency shutdown of the accelerator or accidents of the cold moderator system. In order to obtain a technical data for design and safety review of the liquid-hydrogen system, we have fabricated an experimental apparatus simulated the cold moderator system using liquid nitrogen (max. 1.5 MPa, mini. 77 K) instead of liquid hydrogen. The experiments on a controllability of the system were carried out to investigate dynamic characteristics of the system. This report presents the experimental results and technical issues for the co...

  9. Experimental results obtained with the simulated cold moderator system. System characteristics and technical issues

    Energy Technology Data Exchange (ETDEWEB)

    Aso, Tomokazu; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Takahashi, Toshio; Hino, Ryutaro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-12-01

    The Japan Atomic Energy Research Institute and the High Energy Accelerator Research Organization have been developing a Mega-Watt scale spallation target system. In the system, neutrons generated in a target are sorted out their energy to the proper values in liquid-hydrogen moderators. Then, the liquid-hydrogen is forced to circulate in order to suppress hydrogen temperature increase. In the operation of moderators, it is very important to establish a safety protection system against emergency shutdown of the accelerator or accidents of the cold moderator system. In order to obtain a technical data for design and safety review of the liquid-hydrogen system, we have fabricated an experimental apparatus simulated the cold moderator system using liquid nitrogen (max. 1.5 MPa, mini. 77 K) instead of liquid hydrogen. The experiments on a controllability of the system were carried out to investigate dynamic characteristics of the system. This report presents the experimental results and technical issues for the construction of a practical liquid-hydrogen moderator system of the Mega-Watt scale target system. (author)

  10. Impact of new ingredients obtained from brewer's spent yeast on bread characteristics.

    Science.gov (United States)

    Martins, Z E; Pinho, O; Ferreira, I M P L V O

    2018-05-01

    The impact of bread fortification with β-glucans and with proteins/proteolytic enzymes from brewers' spent yeast on physical characteristics was evaluated. β-Glucans extraction from spent yeast cell wall was optimized and the extract was incorporated on bread to obtain 2.02 g β-glucans/100 g flour, in order to comply with the European Food Safety Authority guidelines. Protein/proteolytic enzymes extract from spent yeast was added to bread at 60 U proteolytic activity/100 g flour. Both β-glucans rich and proteins/proteolytic enzymes extracts favoured browning of bread crust. However, breads with proteins/proteolytic enzymes addition presented lower specific volume, whereas the incorporation of β-glucans in bread lead to uniform pores that was also noticeble in terms of higher specific volume. Overall, the improvement of nutritional/health promoting properties is highlighted with β-glucan rich extract, not only due to bread β-glucan content but also for total dietary fibre content (39% increase). The improvement was less noticeable for proteins/proteolytic enzymes extract. Only a 6% increase in bread protein content was noted with the addition of this extract and higher protein content would most likely accentuate the negative impact on bread specific volume that in turn could impair consumer acceptance. Therefore, only β-glucan rich extract is a promising bread ingredient.

  11. Experiments on condensation heat transfer characteristics inside a microfin tube with R410A

    Energy Technology Data Exchange (ETDEWEB)

    Han, D H; Cho, Y J [Korea University Graduate School, Seoul (Korea); Lee, K J; Park, S S [Korea University, Seoul (Korea)

    2000-11-01

    Due to the ozone depletion and global warming potentials, some refrigerants (CFCs and HCFCs) have been rapidly substituted. R410A is considered as the alternative refrigerant of R22 for the air-conditioners used at home and in industry. Experiments on the condensation heat transfer characteristics inside a smooth or a micro-fin tube with R410A are performed in this study. The test tubes 7/9.52 mm in outer diameters and 3 m in length are used. Varying the mass flux of the refrigerant and the condensation temperatures, the average heat transfer coefficients and pressure drop are investigated. It is shown that the heat transfer is enhanced and the amount of pressure drops are larger in the microfin tube than the smooth tube. From the heat transfer enhancement coefficient and the pressure penalty factor, it is found that the high heat transfer enhancement coefficients are obtained in the range of small mass flux while the penalty factors are almost equal. (author). 13 refs., 12 figs., 1 tab.

  12. Characteristics of confining ohm-heated plasma in TRIAM-IM

    International Nuclear Information System (INIS)

    Hatae, Takaki; Yamagajyo, Takashi; Kawasaki, Shoji; Jotaki, Eriko; Fujita, Takaaki; Nakamura, Kazuo; Nakamura, Yukio; Ito, Satoshi

    1994-01-01

    In the initial experiment after the increase of the power of ohm heating power source for the superconducting strong magnetic field tokamak, TRIAM-IM, the measurement of the electron temperature distribution, ion temperature distribution and beam average electron density of ohm-heated plasma was carried out. By analyzing the experimental results, the dependence of the accumulated energy obtained from the temperature distribution and the time of energy confinement of beam average electron density became clear. Especially the time of energy confinement increased in proportion to the increase of beam average electron density when it is 6.5 x 10 12 /m 2 , and it was found that the time of energy confinement conforms to the Neo-Alcator proportional law. Moreover, by solving the heat transport equation for ions, the radial distribution of thermal diffusion coefficient for ions was calculated, and compared with that obtained by the new classic theory. As the result, it was found that the TRIAM-IM has ion confinement characteristics equivalent to those of other medium tokamaks. The experiment of producing ohm-heated plasma, the fitting of electron temperature and ion temperature, the density dependence of temperature, accumulated energy and the time of energy confinement, the time of energy confinement and the Neo-Alcator proportional law, the energy balance of ions and so on are reported. (K.I.)

  13. Heat transfer characteristics of supercritical pressure waster in vertical upward annular channels

    International Nuclear Information System (INIS)

    Wang Han; Bi Qincheng; Yang Zhendong; Wu Gang

    2013-01-01

    Within the range of pressure from 23 to 28 MPa, mass flux from 350 to 1000 kg/(m 2 · s), and outside wall heat flux from 200 to 1000 kW/m 2 , experimental investigation was conducted on the heat transfer characteristics of supercritical pressure water in vertical upward annular channels. The effects of heat flux, pressure, mass flux and spiral spacer on heat transfer were analyzed, and two types of heat transfer deterioration occurred in the experiments were compared. The experimental results show that the heat transfer of water can be enhanced by increasing the mass flux or decreasing the wall heat flux. The effect of pressure on heat transfer is not uniform and depends on heat transfer form. It was found that the spiral spacer not only enhances the heat transfer of water, but also delays the heat transfer deterioration which occurs in high heat flux and low mass flux conditions. (authors)

  14. Study of the physicochemical characteristics of soursop powder obtained by spray-drying

    Directory of Open Access Journals (Sweden)

    Janaina de Paula da Costa

    2014-12-01

    Full Text Available This study aimed at contributing to the development of new foodstuffs made by soursop pulp powder obtained by spraydrying. Different concentrations of maltodextrin DE 20 (15, 30, and 45% were added to commercial soursop pulp, which was dehydrated afterwards. The following analyses were carried out: water activity, moisture, pH, soluble solids, acidity, ascorbic acid, hygroscopicity, degree of caking, and rehydration time. The results obtained for the three powder treatments (15, 30 and 45% of maltodextrin were, respectectively: water activity (0.19a±0.00; 0.20a±0.00; 0.18a±0.01; moisture (1.17c±0.12; 1.47b±0.05; 1.82a±0.06; pH (3.75a±0.05; 3.73a±0.06; 3.70a±0.03; soluble solids (89.67a±0.00; 89.84a±0.00; 90.00a±0.06; acidity (3.01a±0.02; 1.91b±0.03; 1.24c±0.03; ascorbic acid (18.90a±0.00; 14.48b±0.00; 11.26b±0.78; hygroscopicity (5.93a±0.40; 3.82b±0.16; 3.28b±0.38; degree of caking (78.36a±2.86; 35.38b±6.07; 24.77b4.89, and rehydration time (02.03a±0.46; 01.16ab±0.50; 0.59b±0.30. The soursop powders with 30 and 45% of maltodextrin had few significant differences in terms of physicochemical and hygroscopic characteristics, which allow us to consider the percentage of 30% of maltodextrin, in this study, as the best percentage for soursop pulp atomization.

  15. Study of radiation heating (part 1). UR spectroscopic characteristics of radiant heat source

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Yoshikazu; Ajisaka, Kazuhiro; Toyonaga, Hajime; Kitahata, Hiroki; Oshida, Shun' ichi; Sugihara, Tomonori

    1987-09-01

    There are many IR permeable substances. When this is heated with IR beam, UR beam penetrated into the substance and heat up the substance from the inside. In this case, the inside gets hot quicker than the surface which gives much difference in the finish of the product. Characteristics of permeation and absorption of the IR beam vary by the type of the substance and the wave-length of the UR beam. Examples of effectiveness of far infra-red heater are: Baking of rice cake. Baking of PVC granules as a slip-stop for a working gloves. Far infra-red sauna (sweating effect around 50/sup 0/C). Tokyo Gas Co., Ltd. and other companies introduced an IR spectroscopic radiometer of Minarad Systems of USA to establish a data exchange system in 1984. The spectroscopic radio-meter system consists of 3 components, i.e., a spectrophotometric radiometer, a black body furnace, and a computer for data processing. (14 figs, 5 tabs)

  16. Structural characteristics of pumpkin pectin extracted by microwave heating.

    Science.gov (United States)

    Yoo, Sang-Ho; Lee, Byeong-Hoo; Lee, Heungsook; Lee, Suyong; Bae, In Young; Lee, Hyeon Gyu; Fishman, Marshall L; Chau, Hoa K; Savary, Brett J; Hotchkiss, Arland T

    2012-11-01

    To improve extraction yield of pumpkin pectin, microwave heating was adopted in this study. Using hot acid extraction, pumpkin pectin yield decreased from 5.7% to 1.0% as pH increased from pH 1.0 to 2.0. At pH 2.5, no pectin was recovered from pumpkin flesh powder. After a pretreatment at pH 1.0 and 25 °C for 1 h, pumpkin powder was microwave-extracted at 120 °C for 3 min resulting in 10.5% of pectin yield. However, premicrowave treatment at 60 °C for 20 min did not improve extraction yield. When microwave heating at 80 °C for 10 min was applied after premicrowave treatment, final pectin yield increased to 11.3%. When pH was adjusted to 2.0, the yield dropped to 7.7% under the same extraction conditions. Molecular shape and properties as well as chemical composition of pumpkin pectin were significantly affected depending on extraction methods. Galacturonic acid content (51% to 58%) of pumpkin pectin was lower than that detected in commercial acid-extracted citrus pectin, while higher content of neutral sugars and acetyl esters existed in pumpkin pectin structure. Molecular weight (M(w) ) and intrinsic viscosity (η(w) ) determined for microwave-extracted pumpkin pectins were substantially lower than acid-extracted pectin, whereas polydispersity was greater. However, microwave-extracted pectin at pH 2.0 had more than 5 times greater M(w) than did the pectin extracted at pH 1.0. The η(w) of microwave-extracted pectin produced at pH 2.0 was almost twice that of other microwave-extracted pectins, which were comparable to that of acid-extracted pectin. These results indicate that extraction yield of pumpkin pectin would be improved by microwave extraction and different pectin structure and properties can be obtained compared to acid extraction. Pumpkin is a promising alternative source for pectin material. Pumpkin pectin has a unique chemical structure and physical properties, presumably providing different functional properties compared to conventional commercial

  17. Experimental study on external condensation heat transfer characteristics of bellows

    International Nuclear Information System (INIS)

    Feng Dianyi; Hu Jiansheng

    2008-01-01

    Flow model and heat transfer of condensation flow outside of bellows have been theoretically and experimentally studied. The formula for calculation of condensation heat transfer coefficient was deduced, and corrected through experiment. The calculation results are accordant with the experimental ones, and the errors is less than 10%. The effect of bellows structure parameters and pipe diameter on the enhancement heat transfer has been investigated. It is found that in the steady flow region, the average condensation heat transfer coefficient in a bellows is 3 ∼ 5 times than that in a straight tube under the same conditions, and when considering the increasing in heat transfer area, the effectiveness of enhancement heat transfer is 5 ∼ 7 times than that in a straight tube. To facilitate the engineering design and application of bellows, the formula for the calculation of the average heat transfer coefficient of a fluid in a bellows was also given. (authors)

  18. Mathematical Model for Localised and Surface Heat Flux of the Human Body Obtained from Measurements Performed with a Calorimetry Minisensor

    Science.gov (United States)

    Socorro, Fabiola; Rodríguez de Rivera, Pedro Jesús; Rodríguez de Rivera, Miriam

    2017-01-01

    The accuracy of the direct and local measurements of the heat power dissipated by the surface of the human body, using a calorimetry minisensor, is directly related to the calibration rigor of the sensor and the correct interpretation of the experimental results. For this, it is necessary to know the characteristics of the body’s local heat dissipation. When the sensor is placed on the surface of the human body, the body reacts until a steady state is reached. We propose a mathematical model that represents the rate of heat flow at a given location on the surface of a human body by the sum of a series of exponentials: W(t) = A0 + ∑Aiexp(−t/τi). In this way, transient and steady states of heat dissipation can be interpreted. This hypothesis has been tested by simulating the operation of the sensor. At the steady state, the power detected in the measurement area (4 cm2) varies depending on the sensor’s thermostat temperature, as well as the physical state of the subject. For instance, for a thermostat temperature of 24 °C, this power can vary between 100–250 mW in a healthy adult. In the transient state, two exponentials are sufficient to represent this dissipation, with 3 and 70 s being the mean values of its time constants. PMID:29182567

  19. Mathematical Model for Localised and Surface Heat Flux of the Human Body Obtained from Measurements Performed with a Calorimetry Minisensor.

    Science.gov (United States)

    Socorro, Fabiola; Rodríguez de Rivera, Pedro Jesús; Rodríguez de Rivera, Miriam; Rodríguez de Rivera, Manuel

    2017-11-28

    The accuracy of the direct and local measurements of the heat power dissipated by the surface of the human body, using a calorimetry minisensor, is directly related to the calibration rigor of the sensor and the correct interpretation of the experimental results. For this, it is necessary to know the characteristics of the body's local heat dissipation. When the sensor is placed on the surface of the human body, the body reacts until a steady state is reached. We propose a mathematical model that represents the rate of heat flow at a given location on the surface of a human body by the sum of a series of exponentials: W ( t ) = A ₀ + ∑A i exp( -t / τ i ). In this way, transient and steady states of heat dissipation can be interpreted. This hypothesis has been tested by simulating the operation of the sensor. At the steady state, the power detected in the measurement area (4 cm²) varies depending on the sensor's thermostat temperature, as well as the physical state of the subject. For instance, for a thermostat temperature of 24 °C, this power can vary between 100-250 mW in a healthy adult. In the transient state, two exponentials are sufficient to represent this dissipation, with 3 and 70 s being the mean values of its time constants.

  20. Experimental Study of Evaporative Heat Transfer Characteristics of R-134a with Channel-Bending Angle in Microchannel Heat Exchangers

    International Nuclear Information System (INIS)

    Lee, Hae Seung; Jeon, Dong Soon; Kim, Young Lyoul; Kim, Seon Chang

    2010-01-01

    Experimental investigations have been carried out to examine the evaporative heat transfer characteristics of R-134a with the channel-bending angle (CBA) in microchannel heat exchangers. In this study, we examined the effects of evaporation temperature and Reynolds number of R-134a on the evaporative heat transfer characteristics of R-134a in microchannel heat exchangers with CBAs of 120 .deg. , 150 .deg. , and 180 .deg. under counterflow conditions. Experimental results show that the evaporative heat transfer rate and evaporative heat transfer coefficient increased with an increase in the Reynolds number of R-134a. Further, the evaporative heat transfer rate corresponding to CBAs of 120 .deg. and 150 .deg. increased to values greater than the evaporative heat transfer rate corresponding to 180 .deg. by approximately 17.1% and 13.3%, respectively, for evaporating temperatures in the range 4.9-14.9 .deg. C. The evaporative heat transfer coefficient was affected by the channel angle with increasing evaporative heat transfer coefficient at small channel bending angle

  1. Heat transfer characteristics evaluation of heat exchangers of mock-up test facility with full-scale reaction tube for HTTR hydrogen production system (Contract research)

    International Nuclear Information System (INIS)

    Shimizu, Akira; Ohashi, Hirofumi; Kato, Michio; Hayashi, Koji; Aita, Hideki; Nishihara, Tetsuo; Inaba, Yoshitomo; Takada, Shoji; Morisaki, Norihiro; Sakaki, Akihiro; Maeda, Yukimasa; Sato, Hiroyuki; Inagaki, Yoshiyuki; Hanawa, Hiromi; Fujisaki, Katsuo; Yonekawa, Hideo

    2005-06-01

    Connection of hydrogen production system by steam reforming of methane to the High Temperature Engineering Test Reactor (HTTR) of the Japan Atomic Energy Research Institute (JAERI) has been surveyed until now. Mock-up test facility of this steam reforming system with full-scale reaction tube was constructed in FY 2001 and hydrogen of 120 Nm 3 /h was successfully produced in overall performance test. Totally 7 times operational tests were performed from March 2002 to December 2004. A lot of operational test data on heat exchanges were obtained in these tests. In this report specifications and structures of steam reformer, steam superheater, steam generator, condenser, helium gas cooler, feed gas heater and feed gas superheater were described. Heat transfer correlation equations for inside and outside tube were chosen from references. Spreadsheet programs were newly made to evaluate heat transfer characteristics from measured test data such as inlet and outlet temperature pressure and flow-rate. Overall heat-transfer coefficients obtained from the experimental data were compared and evaluated with the calculated values with heat transfer correlation equation. As a result, actual measurement values of all heat exchangers gave close agreement with the calculated values with correlation equations. Thermal efficiencies of the heat exchangers were adequate as they were well accorded with design value. (author)

  2. Obtaining Material Data for Heat Treatment Simulation of Casr Alloy Parts with Unified Models

    DEFF Research Database (Denmark)

    Bellini, Anna; Thorborg, Jesper; Hattel, Jesper

    2004-01-01

    subjected to high temperature. In this paper a two-state variables unified model is applied in order to simulate creep behavior and time-dependent metallurgical changes. The fundamental assumption of the unified theory is that creep and viscoplasticity, which are both irreversible strains developed because...... study. The results obtained for the simulation of tensile tests and of creep tests are compared with experimental curves, showing a good agreement.......The objective of this work, which is part of the IDEAL (Integrated Development Routes for Optimized Cast Aluminium Components) project, financed by the EU in frame work 6 and born in collaboration with the automobile and foundry industries, is to simulate creep behavior of aluminum cast samples...

  3. The inaccuracy of heat transfer characteristics of insulated and non-insulated circular duct while neglecting the influence of heat radiation

    International Nuclear Information System (INIS)

    Hsien, T.-L.; Wong, K.-L.; Yu, S.-J.

    2009-01-01

    The non-insulated and insulated ducts are commonly applied in the industries and various buildings, because the heat radiation equation contains the 4th order exponential of temperature which is very complicate in calculations. Most heat transfer experts recognized from their own experiences that the heat radiation effect can be ignored due to the small temperature difference between insulated and non-insulated surface and surroundings. This paper studies in detail to check the inaccuracies of heat transfer characteristics non-insulated and insulated duct by comparing the results between considering and neglecting heat radiation effect. It is found that neglecting the heat radiation effect is likely to produce large errors of non-insulated and thin-insulated ducts in situations of ambient air with low external convection heat coefficients and larger surface emissivity, especially while the ambient air temperature is different from that of surroundings and greater internal fluid convection coefficients. It is also found in this paper that using greater duct surface emissivity can greatly improve the heat exchanger effect and using smaller insulated surface emissivity can obtain better insulation.

  4. Influence of heat treatment on field emission characteristics of boron nitride thin films

    International Nuclear Information System (INIS)

    Li Weiqing; Gu Guangrui; Li Yingai; He Zhi; Feng Wei; Liu Lihua; Zhao Chunhong; Zhao Yongnian

    2005-01-01

    Boron nitride (BN) nanometer thin films are synthesized on Si (1 0 0) substrates by RF reactive magnetron sputtering. Then the film surfaces are treated in the case of the base pressure below 5 x 10 -4 Pa and the temperature of 800 and 1000 deg. C, respectively. And the films are studied by Fourier transform infrared spectra (FTIR), atomic force microscopic (AFM) and field emission characteristics at different annealing temperature. The results show that the surface heat treatment makes no apparent influence on the surface morphology of the BN films. The transformations of the sample emission characteristics have to do with the surface negative electron affinity (NEA) of the films possibly. The threshold electric fields are lower for BN samples without heat-treating than the treated films, which possibly ascribed to the surface negative electron affinity effect. A threshold field of 8 V/μm and the emission current of 80 μA are obtained. The surface NEA is still presence at the heat treatment temperature of 800 deg. C and disappeared at temperature of 1000 deg. C

  5. Heat transfer characteristics of horizontal steam generators under natural circulation conditions

    International Nuclear Information System (INIS)

    Hyvaerinen, J.

    1996-01-01

    This paper deals with the heat transfer characteristics of horizontal steam generators, particularly under natural circulation (decay heat removal) conditions on the primary side. Special emphasis is on the inherent features of horizontal steam generator behaviour. A mathematical model of the horizontal steam generator primary side is developed and qualitative results are obtained analytically. A computer code, called HSG, is developed to solve the model numerically, and its predictions are compared with experimental data. The code is employed to obtain for VVER 440 steam generators quantitative results concerning the dependence of primary-to-secondary heat transfer efficiency on the primary side flow rate, temperature and secondary level. It turns out that the depletion of the secondary inventory leads to an inherent limitation of the decay energy removal in VVER steam generators. The limitation arises as a consequence of the steam generator tube bundle geometry. As an example, it is shown that the grace period associated with pressurizer safety valve opening during a station black-out is 2 1/2-3 hours instead of the 5-6 hours reported in several earlier studies. (However, the change in core heat-up timing is much less-about 1 h at most.) The heat transfer limitation explains the fact that, in the Greifswald VVER 440 station black-out accident in 1975, the steam generators never boiled dry. In addition, the stability of single-phase natural circulation is discussed and insights on the modelling of horizontal steam generators with general-purpose thermal-hydraulic system codes are also presented. (orig.)

  6. Experimental investigation on fluid flow and heat transfer characteristics of a submerged combustion vaporizer

    International Nuclear Information System (INIS)

    Han, Chang-Liang; Ren, Jing-Jie; Wang, Yan-Qing; Dong, Wen-Ping; Bi, Ming-Shu

    2017-01-01

    Highlights: • Thermal performance analysis of submerged combustion vaporizer (SCV) was performed experimentally. • Visualization study of shell-side flow field for SCV was carried out. • The effects of various operational parameters on the overall system performance were discussed. • Two new non-dimensional Nusselt correlations were proposed to predict the heat transfer performance of SCV. - Abstract: Submerged combustion vaporizer (SCV) occupies a decisive position in liquefied natural gas (LNG) industrial chain. In this paper, a visual experimental apparatus was established to have a comprehensive knowledge about fluid flow and heat transfer performance of SCV. Trans-critical liquid nitrogen (LN_2) was selected as alternative fluid to substitute LNG because of safety reason. Some unique experimental phenomena inside the SCV (local water bath freezes on the external surface of tube bundle) were revealed. Meanwhile the influences of static water height, superficial flue gas velocity, heat load, tube-side inlet pressure and tube-side mass flux on the system performance were systematically discussed. Finally, based on the obtained experimental results, two new empirical Nusselt number correlations were regressed to predict the shell-side and tube-side heat transfer characteristics of SCV. The maximum errors between predicted results and experimental data were respectively ±25% and ±20%. The outcomes of this paper were critical to the optimum design and economical operation of SCV.

  7. Validity of building characteristics and dorm dampness obtained in a self-administrated questionnaire

    DEFF Research Database (Denmark)

    Sun, Y.X.; Sundell, Jan; Zhang, Y.F.

    2007-01-01

    status), while such problems observed by inspectors were not. The air relative humidity was slightly higher, during winter time, in rooms with condensation on windowpanes. The results indicate that questionnaire surveys give valid data regarding most technical characteristics. With regard to moisture...... characteristics, such as type of surface materials etc., but a poor to slight agreement (kappamoisture damages, such as mould or damp spots, and a mouldy smell, between occupants and inspectors. Dampness problems reported by occupants were associated with health effects (case...

  8. Heat transfer characteristics in a sudden expansion pipe equipped with swirl generators

    International Nuclear Information System (INIS)

    Zohir, A.E.; Abdel Aziz, A.A.; Habib, M.A.

    2011-01-01

    This investigation is aimed at studying the heat transfer characteristics and pressure drop for turbulent airflow in a sudden expansion pipe equipped with propeller type swirl generator or spiral spring with several pitch ratios. The investigation is performed for the Reynolds number ranging from 7500 to 18,500 under a uniform heat flux condition. The experiments are also undertaken for three locations for the propeller fan (N = 15 blades and blade angle of 65 o ) and three pitch ratios for the spiral spring (P/D = 10, 15 and 20). The influences of using the propeller rotating freely and inserted spiral spring on heat transfer enhancement and pressure drop are reported. In the experiments, the swirl generator and spiral spring are used to create a swirl in the tube flow. Mean and relative mean Nusselt numbers are determined and compared with those obtained from other similar cases. The experimental results indicate that the tube with the propeller inserts provides considerable improvement of the heat transfer rate over the plain tube around 1.69 times for X/H = 5. While for the tube with the spiral spring inserts, an improvement of the heat transfer rate over the plain tube around 1.37 times for P/d = 20. Thus, because of strong swirl or rotating flow, the propeller location and the spiral spring pitch become influential on the heat transfer enhancement. The increase in pressure drop using the propeller is found to be three times and for spiral spring 1.5 times over the plain tube. Correlations for mean Nusselt number, fan location and spiral spring pitch are provided.

  9. Numerical studies on heat transfer and pressure drop characteristics of flat finned tube bundles with various fin materials

    Science.gov (United States)

    Peng, Y.; Zhang, S. J.; Shen, F.; Wang, X. B.; Yang, X. R.; Yang, L. J.

    2017-11-01

    The air-cooled heat exchanger plays an important role in the field of industry like for example in thermal power plants. On the other hand, it can be used to remove core decay heat out of containment passively in case of a severe accident circumstance. Thus, research on the performance of fins in air-cooled heat exchangers can benefit the optimal design and operation of cooling systems in nuclear power plants. In this study, a CFD (Computational Fluid Dynamic) method is implemented to investigate the effects of inlet velocity, fin spacing and tube pitch on the flow and the heat transfer characteristics of flat fins constructed of various materials (316L stainless steel, copper-nickel alloy and aluminium). A three dimensional geometric model of flat finned tube bundles with fixed longitudinal tube pitch and transverse tube pitch is established. Results for the variation of the average convective heat transfer coefficient with respect to cooling air inlet velocity, fin spacing, tube pitch and fin material are obtained, as well as for the pressure drop of the cooling air passing through finned tube. It is shown that the increase of cooling air inlet velocity results in enhanced average convective heat transfer coefficient and decreasing pressure drop. Both fin spacing and tube pitch engender positive effects on pressure drop and have negative effects on heat transfer characteristics. Concerning the fin material, the heat transfer performance of copper-nickel alloy is superior to 316L stainless steel and inferior to aluminium.

  10. Analysis of the characteristics of heat transfer enhancement in steam condensers

    International Nuclear Information System (INIS)

    Yan Changqi; Sun Zhongning

    2001-01-01

    The influence of main factors on overall heat transfer was analyzed, and the effects of fouling factors on heat transfer characteristics in steam condenser were clarified. It was proposed that the tube outside enhancement is the most important attribute, when outside heat transfer coefficient increased there will be a big increase in condenser efficiency. The characteristics of heat transfer enhancement by spirally indented tube were investigated. It was proposed that condenser heat transfer efficiency will be raised when the low fin tube or the spirally indented tube with special treated surface were used

  11. Heat transfer and flow characteristics on a gas turbine shroud.

    Science.gov (United States)

    Obata, M; Kumada, M; Ijichi, N

    2001-05-01

    The work described in this paper is an experimental investigation of the heat transfer from the main flow to a turbine shroud surface, which may be applicable to ceramic gas turbines. Three kinds of turbine shrouds are considered with a flat surface, a taper surface and a spiral groove surface opposite to the blades in an axial flow turbine of actual turbo-charger. Heat transfer measurements were performed for the experimental conditions of a uniform heat flux or a uniform wall temperature. The effects of the inlet flow angle, rotational speed, and tip clearance on the heat transfer coefficient were clarified under on- and off-design flow conditions. The mean heat transfer coefficient was correlated to the blade Reynolds number and tip clearance, and compared with an experimental correlation and measurements of a flat surface. A comparison was also made for the measurement of static pressure distributions.

  12. Evaluation of heat transfer characteristics of a sphere-packed pipe for Flibe blanket

    International Nuclear Information System (INIS)

    Watanabe, Atsushi; Ebara, Shinji; Sagara, Akio; Hashizume, Hidetoshi

    2013-01-01

    A Flibe blanket has been proposed to be used in FFHR. Since Flibe has poor heat transfer performance, heat transfer promoter is required, and a sphere-packed pipe (SPP) has been proposed to enhance the heat transfer performance in the Flibe blanket. In this paper, the fluid flow and heat transfer characteristics in the SPP is evaluated numerically using a k–ε turbulent model for the flow field and an algebraic model for the thermal field. As a result, it was shown that bypass flows in the SPP play a significant role in heat transfer. Also it is thought that the turbulent energy can strongly affect heat transfer performance

  13. High-conductivity polymer nanocomposites obtained by tailoring the characteristics of carbon nanotube fillers

    NARCIS (Netherlands)

    Grossiord, N.; Loos, J.; Laake, van L.C.; Maugey, M.; Zakri, C.; Koning, C.E.; Hart, A.J.

    2008-01-01

    We present a detailed study of the influence of carbon nanotube (CNT) characteristics on the electrical conductivity of polystyrene nanocomposites produced using a latex-based approach. We processed both industrially-produced multi-wall CNT (MWCNT) powders and MWCNTs from vertically-aligned films

  14. Pumping time required to obtain tube well water samples with aquifer characteristic radon concentrations

    International Nuclear Information System (INIS)

    Ricardo, Carla Pereira; Oliveira, Arno Heeren de

    2011-01-01

    Radon is an inert noble gas, which comes from the natural radioactive decay of uranium and thorium in soil, rock and water. Radon isotopes emanated from radium-bearing grains of a rock or soil are released into the pore space. Radon that reaches the pore space is partitioned between the gaseous and aqueous phases. Thus, the groundwater presents a radon signature from the rock that is characteristic of the aquifer. The characteristic radon concentration of an aquifer, which is mainly related to the emanation, is also influenced by the degree of subsurface degassing, especially in the vicinity of a tube well, where the radon concentration is strongly reduced. Looking for the required pumping time to take a tube well water sample that presents the characteristic radon concentration of the aquifer, an experiment was conducted in an 80 m deep tube well. In this experiment, after twenty-four hours without extraction, water samples were collected periodically, about ten minutes intervals, during two hours of pumping time. The radon concentrations of the samples were determined by using the RAD7 Electronic Radon Detector from Durridge Company, a solid state alpha spectrometric detector. It was realized that the necessary time to reach the maximum radon concentration, that means the characteristic radon concentration of the aquifer, is about sixty minutes. (author)

  15. Characteristics of Vertical Mantle Heat Exchangers for Solar Water Heaters

    DEFF Research Database (Denmark)

    Shah, Louise Jivan; Morrison, G.L.; Behnia, M.

    1999-01-01

    - The flow structure in vertical mantle heat exchangers was investigated using a full-scale tank designed to facilitate flow visualisation. The flow structure and velocities in the mantle were measured using a particle Image Velocimetry (PIV) system. A CFD simulation model of vertical mantle heat...... exchangers was also developed for detailed evaluation of the heat flux distribution over the mantle surface. Both the experimental and simulation results indicate that distribution of the flow around the mantle gap is governed by buoyancy driven recirculation in the mantle. The operation of the mantle...

  16. A Numerical Study on the Heat Transfer Characteristics of a Solar Thermal Receiver with High-temperature Heat Pipes

    International Nuclear Information System (INIS)

    Park, Young Hark; Jung, Eui Guk; Boo, Joon Hong

    2007-01-01

    A numerical analysis was conducted to predict the heat transfer characteristics of a solar receiver which is subject to very high heat fluxes and temperatures for solar thermal applications. The concentration ratio of the solar receiver ranges from 200 to 1000 and the concentrated heat is required to be transported to a certain distance for specific applications. The study deals with a solar receiver incorporating high-temperature sodium heat pipe as well as typical one that employs a molten-salt circulation loop. The isothermal characteristics in the receiver section is of major concern. The diameter of the solar thermal receiver was 120 mm and the length was 400 mm. For the molten-salt circulation type receiver, 48 axial channels of the same dimensions were attached to the outer wall of the receiver with even spacing in the circumferential direction. The molten salt fed through the channels by forced convection using a special pump. For the heat pipe receiver, the channels are changed to high-temperature sodium heat pipes. Commercial softwares were employed to deal with the radiative heat transfer inside the receiver cavity and the convection heat transfer along the channels. The numerical results are compared and analyzed from the view point of high-temperature solar receiver

  17. Convective heat transfer characteristics in the turbulent region of molten salt in concentric tube

    International Nuclear Information System (INIS)

    Chen, Y.S.; Wang, Y.; Zhang, J.H.; Yuan, X.F.; Tian, J.; Tang, Z.F.; Zhu, H.H.; Fu, Y.; Wang, N.X.

    2016-01-01

    In order to better understand the heat transfer behavior and characteristics of molten salt in heat exchanger, the convective heat transfer characteristics of molten salt in salt-to-oil concentric tube are studied. Overall heat transfer coefficients of the heat exchanger are calculated using Wilson plots. Heat transfer coefficients of tube side molten salt with the range of Reynolds number from 10,000 to 50,000 and the Prandtl number from 11 to 27 are evaluated invoking the calculated overall heat transfer coefficients. The effects of velocity and temperature on the convective heat transfer in the turbulent region of molten salt are studied by comparing with the traditional correlations. The results show that the heat transfer characteristics of molten salt are in line with the empirical heat transfer correlation; however, Dittus–Boelter, Gnielinski, Sieder–Tate and Hausen correlations all give a larger deviation for the experimental data. Finally, based on the experimental data and Sieder–Tate correlation, a modified heat transfer correlation is proposed and good agreement is observed between the experimental data and the modified correlation. The results will also provide an important reference for the design of the heat exchangers in the Thorium-based Molten Salt Reactor.

  18. Heat removal characteristics of waste storage tanks. Revision 1

    International Nuclear Information System (INIS)

    Kummerer, M.

    1995-10-01

    A topical report that examines the relationship between tank heat load and maximum waste temperatures. The passive cooling response of the tanks is examined, and loss of active cooling in ventilated tanks is investigated

  19. Decascading in analysis of gamma family characteristics obtained in X-ray emulsion chambers

    International Nuclear Information System (INIS)

    Vrotnyak, Ya.A.; Tomashevskij, A.; Yushkevich, R.M.

    1976-01-01

    The purpose of the investigation is to ascertain how decascading (D) restores the initial characteristics of γ-quanta families and how this restoration depends on the choice of the parameter D associated with the altitude of γ-quanta generation. This investigation shows to what extent D is useful in analysing families formed in several acts at different altitudes. In casting Monte Carlo lots for separate events a nuclear act model is used in the form of successive Hasegawa's H-quanta. The calculations have been made for primary nucleon energies of 200, 400, 800, and 1600 TeV and for generation altitudes of 560, 1100, and 2200 m above the sea level (the adopted observation level is 4500 m above the sea level). It is considered that the use of the D method largely eliminates the effect of electromagnetic cascade processes in the atmosphere on the characteristics of ''pure'' families. In the case of ''impure'' families this elimination is also considerable. D must increase the sensitivity of the characteristics of experimental and artificial γ-families to the elementary act parameters

  20. Conjugate heat transfer analysis of an energy conversion device with an updated numerical model obtained through inverse identification

    International Nuclear Information System (INIS)

    Hey, Jonathan; Malloy, Adam C.; Martinez-Botas, Ricardo; Lamperth, Michael

    2015-01-01

    Highlights: • Conjugate heat transfer analysis of an electric machine. • Inverse identification method for estimating the model parameters. • Experimentally determined thermal properties and electromagnetic losses. • Coupling of inverse identification method with a numerical model. • Improved modeling accuracy through introduction of interface material. - Abstract: Energy conversion devices undergo thermal loading during their operation as a result of inefficiencies in the energy conversion process. This will eventually lead to degradation and possible failure of the device if the heat generated is not properly managed. The ability to accurately predict the thermal behavior of such a device during the initial developmental stage is an important requirement. However, accurate predictions of critical temperature is challenging due to the variation of heat transfer parameters from one device to another. The ability to determine the model parameters is key to accurately representing the heat transfer in such a device. This paper presents the use of an inverse identification technique to estimate the model parameters of an energy conversion device designed for vehicular applications. To simulate the imperfect contact and the presence of insulating materials in the permanent magnet electric machine, thin material are introduced at the component interface of the numerical model. The proposed inverse identification method is used to estimate the equivalent thermal conductance of the thin material. In addition, the electromagnetic losses generated in the permanent magnet is also derived indirectly from the temperature measurement using the same method. With the thermal properties and input parameters of the numerical model obtained from the inverse identification method, the critical temperature of the device can be predicted more accurately. The deviation between the maximum measured and predicted winding temperature is less than 2.4%

  1. Heating characteristics of billet in a walking hearth type reheating furnace

    International Nuclear Information System (INIS)

    Emadi, Ali; Saboonchi, Ahmad; Taheri, Mahdi; Hassanpour, Saeid

    2014-01-01

    The heating characteristics of billet in a walking hearth type reheating furnace were studied by developing a mathematical heat transfer model. Radiation calculations were conducted by means of zone method and considering all radiation exchange paths. The weighted-sum-of-gray-gas-model was used for better accuracy of gas radiation prediction. Convective heat flux was calculated by considering suitable value of convective heat transfer coefficient at any location of the furnace. The model was substantiated through its comparison to experimental data. A comparison was drawn to evaluate the effect of constant and variable convective coefficient on convective flux distribution and billet thermal behavior. The effect of furnace wall's emissivity of each zone and whole of the furnace on the billet thermal behavior was investigated. The obtained results revealed that by increasing furnace wall's emissivity for a determined residence time, billet's temperature in primary zones rises but it has no significant effect on its final temperature. However, by increasing wall's emissivity from 0.7 to 0.95, the residence time can be declined by about 5%. Moreover, emissivity increase in non-firing and preheating zones as compared to heating and soaking zones has greater impact on the billet thermal behavior. -- Highlights: • 3D radiation modeling by considering all possible paths of radiation exchange. • Using WSGG model for better prediction of gas radiation. • Using non-constant convection coefficient to consider variation of gas mass flow. • Investigation of effect of convection coefficient on billet temperature behavior. • Investigation of wall emissivity of furnace zones

  2. Flow characteristics and heat transfer performances of a semi-confined impinging array of jets: effect of nozzle geometry

    Energy Technology Data Exchange (ETDEWEB)

    Dano, B.P.E.; Liburdy, J.A. [Oregon State Univ., Corvallis, OR (United States). Dept. of Mechanical Engineering; Kanokjaruvijit, Koonlaya [Imperial College, London (United Kingdom). Dept. of Mechanical Engineering

    2005-02-01

    The flow and heat transfer characteristics of confined jet array impingement with crossflow is investigated. Discrete impingement pressure measurements are used to obtain the jet orifice discharge flow coefficient. Digital particle image velocimetry (DPIV) and flow visualization are used to determine the flow characteristics. Two thermal boundary conditions at the impinging surface are presented: an isothermal surface, and a uniform heat flux, where thermocouple and thermochromic liquid crystal methods were used, respectively, to determine the local heat transfer coefficient. Two nozzle geometries are studied, circular and cusped ellipse. Based on the interaction with the jet impingement at the surface, the crossflow is shown to influence the heat transfer results. The two thermal boundary conditions differ in overall heat transfer correlation with the jet Reynolds number. Detailed velocity data show that the flow development from the cusped ellipse nozzle affects the wall region flow more than the circular nozzle, as influenced by the crossflow interactions. The overall heat transfer for the uniform heat flux boundary condition is found to increase for the cusped ellipse orifice. (Author)

  3. Analysis on flow characteristic of nuclear heating reactor

    International Nuclear Information System (INIS)

    Jiang Shengyao; Wu Xinxin

    1997-06-01

    The experiment was carried out on the test loop HRTL-5, which simulates the geometry and system design of a 5 MW Nuclear heating reactor. The analysis was based on a one-dimensional two-phase flow drift model with conservation equations for mass, steam mass, energy and momentum. Clausius-Clapeyron equation was used for the calculation of flashing front in the riser. A set of ordinary equation, which describes the behavior of two-phase flow in the natural circulation system, was derived through integration of the above conservation equations in subcooled boiling region, bulk boiling region in the heated section and in the riser. The method of time-domain was used for the calculation. Both static and dynamic results are presented. System pressure, inlet subcooling and heat flux are varied as input parameters. The results show that, firstly, subcooled boiling in the heated section and void flashing in the riser have significant influence on the distribution of the void fraction, mass flow rate and stability of the system, especially at lower pressure, secondly, in a wide range of two-phase flow conditions, only subcooled boiling occurs in the heated section. For the designed two-phase regime operation of the 5 MW nuclear heating reactor, the temperature at the core exit has not reaches its saturation value. Thirdly, the mechanism of two-phase flow oscillation, namely, 'zero-pressure-drop', is described. In the wide range of inlet subcooling (0 K<ΔT<28 K) there exists three regions for system flow condition, namely, (1) stable two-phase flow, (2) bulk and subcooled boiling unstable flow, (3) subcooled boiling and single phase stable flow. The response of mass flow rate, after a small disturbance in the heat flux, is showed in the above inlet subcooling range, and based on it the instability map of the system is given through experiment and calculation. (3 refs., 9 figs.)

  4. Operational characteristics of miniature loop heat pipe with flat evaporator

    Energy Technology Data Exchange (ETDEWEB)

    Gai, Dongxing; Liu, Zhichun; Liu, Wei; Yang, Jinguo [Huazhong University of Science and Technology, School of Energy and Power Engineering, Wuhan, Hubei (China)

    2009-12-15

    Loop heat pipes are heat transfer devices whose operating principle is based on the evaporation and condensation of a working fluid, and which use the capillary pumping forces to ensure the fluid circulation. A series of tests have been carried out with a miniature loop heat pipe (mLHP) with flat evaporator and fin-and-tube type condenser. The loop is made of pure copper with stainless mesh wick and methanol as the working fluid. Detailed study is conducted on the start-up reliability of the mLHP at high as well as low heat loads. During the testing of mLHP under step power cycles, the thermal response presented by the loop to achieve steady state is very short. At low heat loads, temperature oscillations are observed throughout the loop. The amplitudes and frequencies of these fluctuations are large at evaporator wall and evaporator inlet. It is expected that the extent and nature of the oscillations occurrence is dependent on the thermal and hydrodynamic conditions inside the compensation chamber. The thermal resistance of the mLHP lies between 0.29 and 3.2 C/W. The effects of different liquid charging ratios and the tilt angles to the start-up and the temperature oscillation are studied in detail. (orig.)

  5. Experimental and numerical study of waste heat recovery characteristics of direct contact thermoelectric generator

    International Nuclear Information System (INIS)

    Kim, Tae Young; Negash, Assmelash; Cho, Gyubaek

    2017-01-01

    Highlights: • Energy harvesting performance of direct contact thermoelectric generator was studied. • Power-current and voltage-current curves were given for various operating conditions. • Output power prediction using numerical results and empirical correlation was verified. • A 1.0–2.0% conversion efficiency and 5.7–11.1% heat recovery efficiency were obtained. • A 0.25% increase in efficiency was found with a 10 K decrease in coolant temperature. - Abstract: In this study, waste heat recovery performance of a direct contact thermoelectric generator (DCTEG) is experimentally investigated on a diesel engine. In order to conduct an insightful analysis of the DCTEG characteristics, three experimental parameters—engine load, rotation speed, and coolant temperature—are chosen to vary over ranges during the experiments. Experimental results show that higher temperature differences across thermoelectric modules (TEM), larger engine loads, and rotation speeds lead to an improved energy conversion efficiency of the DCTEG, which lies in the range of approximately 1.0–2.0%, while the output power ranges approximately 12–45 W. The increase in the conversion efficiency for an increased engine load becomes more noticeable with a higher engine rotation speed. A 10 K decrease in the coolant temperature yields an approximately 0.25% increase in the conversion efficiency for the engine operating conditions tested. In addition, 3D numerical simulations were conducted to investigate the heat transfer and pressure characteristics of the DCTEG. Numerically obtained exhaust gas temperatures exiting the DCTEG were in good agreement with experimental results. It is also revealed that incorporation of the temperature fields from the numerical simulation and an empirical correlation for a temperature-power relationship provides a good predictor for output power from the DCTEG, especially at low engine load conditions, which deviates from experimental results as the

  6. Emission characteristics of biodiesel obtained from jatropha seeds and fish wastes in a diesel engine

    OpenAIRE

    Bhaskar Kathirvelu; Sendilvelan Subramanian; Nagarajan Govindan; Sampath Santhanam

    2017-01-01

    The concept of waste recycling and energy recovery plays a vital role for the development of any economy. The reuse of fish waste and use of wasteland for cultivation of jatropha seeds have led to resource conservation and their use as blend with diesel as an alternative fuel to diesel engines has contributed to pollution reduction. In this work, the results of using blends of biodiesel obtained from jatropha seeds, fish wastes and diesel in constant speed diesel engines are presented. The ex...

  7. Characteristics of Biochar Obtained by Hydrothermal Carbonization of Cellulose for Renewable Energy

    OpenAIRE

    Daegi Kim; Kunio Yoshikawa; Ki Young Park

    2015-01-01

    The effect of hydrothermal carbonization on the properties of cellulose present in lignocellulosic biomass was investigated for converting it into a renewable energy resource with high energy recovery efficiency. The biochar obtained from cellulose subjected to hydrothermal carbonization showed a significant increase in its carbon content and a calorific value. 13C NMR spectroscopy showed that when raw cellulose was subjected to hydrothermal carbonization above 220 °C, the resulting biochar h...

  8. Review of thermo-physical properties, wetting and heat transfer characteristics of nanofluids and their applicability in industrial quench heat treatment.

    Science.gov (United States)

    Ramesh, Gopalan; Prabhu, Narayan Kotekar

    2011-04-14

    The success of quenching process during industrial heat treatment mainly depends on the heat transfer characteristics of the quenching medium. In the case of quenching, the scope for redesigning the system or operational parameters for enhancing the heat transfer is very much limited and the emphasis should be on designing quench media with enhanced heat transfer characteristics. Recent studies on nanofluids have shown that these fluids offer improved wetting and heat transfer characteristics. Further water-based nanofluids are environment friendly as compared to mineral oil quench media. These potential advantages have led to the development of nanofluid-based quench media for heat treatment practices. In this article, thermo-physical properties, wetting and boiling heat transfer characteristics of nanofluids are reviewed and discussed. The unique thermal and heat transfer characteristics of nanofluids would be extremely useful for exploiting them as quench media for industrial heat treatment.

  9. Review of thermo-physical properties, wetting and heat transfer characteristics of nanofluids and their applicability in industrial quench heat treatment

    Directory of Open Access Journals (Sweden)

    Ramesh Gopalan

    2011-01-01

    Full Text Available Abstract The success of quenching process during industrial heat treatment mainly depends on the heat transfer characteristics of the quenching medium. In the case of quenching, the scope for redesigning the system or operational parameters for enhancing the heat transfer is very much limited and the emphasis should be on designing quench media with enhanced heat transfer characteristics. Recent studies on nanofluids have shown that these fluids offer improved wetting and heat transfer characteristics. Further water-based nanofluids are environment friendly as compared to mineral oil quench media. These potential advantages have led to the development of nanofluid-based quench media for heat treatment practices. In this article, thermo-physical properties, wetting and boiling heat transfer characteristics of nanofluids are reviewed and discussed. The unique thermal and heat transfer characteristics of nanofluids would be extremely useful for exploiting them as quench media for industrial heat treatment.

  10. Analytic continuation of scattering data as a method of obtaining characteristics of bound states

    International Nuclear Information System (INIS)

    Blokhintsev, L.; Savin, D.

    2014-01-01

    An asymptotic normalization coefficient (ANC) determines the asymptotics of a wave function of a nucleus a in a binary channel b + c. ANCs are proportional to nuclear vertex constants (NVCs), which are on-shell matrix elements of the virtual processes a ↔ b+c. The method of the analytic continuation of the effective range function is applied to obtain the asymptotic normalization coefficients for 6 Li nucleus in the α+ d channel. Several sets of scattering phases obtained from the phase-shift analyses as well as from Faddeev calculations are used as an input. Since the α+d system possesses the low-lying inelastic threshold due to the dissociation of a deuteron, the approach used is generalized to include inelastic channels. The sensitivity of the obtained values of asymptotic normalization coefficients to the elastic channels coupling and to account of the inelastic channel is investigated. In summary, we can say that employing the analytic continuation of the effective range expansion to determine the ANCs and NVCs for the 6 Li → α + d channel turns out to be successful

  11. HEATING CHARACTERISTICS OF SOFTWOODS IN A HIGH FREQUENCY FIELD

    Directory of Open Access Journals (Sweden)

    Ciprian LĂZĂRESCU

    2012-12-01

    Full Text Available The research aimed to establish whetherdielectric heating at radio frequencies might be afeasible option for phytosanitation of green softwoodboards. Results are presented for two softwoodspecies, namely, lodgepole pine (Pinus contorta andwestern red cedar (Thujaplicata Donn., and forsingle-specimen testing configurations with a crosssection of 40x90mm surrounded on three sides bysimilar cross-section kiln dried boards. In terms ofdielectric properties, red cedar is nature "designed" toabsorb more easily the dielectric fields. Heating rateswere not correlated with moisture content for neitherspecies investigated thus underlining the versatility ofRF-heating that allows simultaneous rise oftemperature within dry and wet areas. Convectionlosses through air contact may reduce the averageheating rate of the shell by about 40%.

  12. Radiators in hydronic heating installations structure, selection and thermal characteristics

    CERN Document Server

    Muniak, Damian Piotr

    2017-01-01

    This book addresses key design and computational issues related to radiators in hydronic heating installations. A historical outline is included to highlight the evolution of radiators and heating technologies. Further, the book includes a chapter on thermal comfort, which is the decisive factor in selecting the ideal heating system and radiator type. The majority of the book is devoted to an extensive discussion of the types and kinds of radiators currently in use, and to identifying the reasons for the remarkable diversity of design solutions. The differences between the solutions are also addressed, both in terms of the effects of operation and of the thermal comfort that needs to be ensured. The book then compares the advantages and disadvantages of each solution, as well as its potential applications. A detailed discussion, supported by an extensive theoretical and mathematical analysis, is presented of the computational relations that are used in selecting the radiator type. The dynamics of radiator hea...

  13. Studies on the characteristics of the separated type heat pipe system with non-condensible gas for the use of the passive decay heat removal in reactor systems

    International Nuclear Information System (INIS)

    Hayashi, Takao; Iigaki, Kazuhiko; Ohashi, Kazutaka; Hayakawa, Hitoshi; Yamada, Masao.

    1995-01-01

    This study is the fundamental research by experiments to aim at the development of the complete passive decay heat removal system on the modular reactor systems by the form of the separated type of heat pipe system utilizing the features of both the big latent heat for vaporization from water to steam and easy transportation characteristics. Special intention in our study on the fundamental experiments is to look for the effects in such a separated type of heat pipe system to introduce non-condensible gas such as nitrogen gas together with the working fluid of water. Many interesting findings have been obtained so far on the experiments for the variable conductance heat pipe characteristics from viewpoint of the actual application on the aim said above. This study has been carried out by the joint study between Tokai University and Fuji Electric Co., Ltd. and this paper is made up from the several papers presented so far at both the national and international symposiums under the name of joint study of the both bodies. (author)

  14. Adsorption characteristics of heat-treated fullerene nano-whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z-M [Energy Storage Materials Group, Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Kato, R; Hotta, K; Miyazawa, K [Fullerene Engineering Group, Advanced Nano Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)], E-mail: zm-wang@aist.go.jp

    2009-04-01

    Fullerene nanowhiskers (FNWs) were synthesized by the liquid-liquid interfacial precipitation method and the adsorption properties of their heat-treated samples were characterized. It was found that vacuum-annealed FNWs at a high temperature are of microporous materials and, especially, ultramicropores are highly developed in these materials. Porosities even remain in samples after heat treatment at a temperature higher than 2273 K. The presence of ultramicroporosity is indicative of the molecular sieving properties of the vacuum-annealed FNW materials, suggesting the possibilities of their application as new materials for gas separation and gas storage.

  15. Heat Transfer Characteristics in High Power LED Packaging

    Directory of Open Access Journals (Sweden)

    Chi-Hung Chung

    2014-03-01

    Full Text Available This study uses the T3Ster transient thermal resistance measuring device to investigate the effects to heat transfer performances from different LED crystal grains, packaging methods and heat-sink substrates through the experimental method. The experimental parameters are six different types of LED modules that are made alternatively with the crystal grain structure, the die attach method and the carrying substrate. The crystal grain structure includes the lateral type, flip chip type and vertical type. The die attach method includes silver paste and the eutectic structure. The carrying substrates are aluminum oxide (Alumina and aluminum nitride (AIN ceramic substrates and metal core PCB (MCPCB. The experimental results show that, under the conditions of the same crystal grain and die attach method, the thermal resistance values for the AIN substrate and the Alumina substrate are 2.1K/W and 5.1K/W, respectively and the total thermal resistance values are 7.3K/W and 10.8K/W. Compared to the Alumina substrate, the AIN substrate can effectively lower the total thermal resistance value by 32.4%. This is because the heat transfer coefficient of the AIN substrate is higher than that of the Alumina substrate, thus effectively increasing its thermal conductivity. In addition, under the conditions of the same crystal grain and the same substrate, the packaging methods are using silver paste and the eutectic structure for die attach. Their thermal resistance values are 5.7K/W and 2.7K/W, respectively, with a variance of 3K/W. Comparisons of the crystal grain structure show that the thermal resistance for the flip chip type is lower than that of the traditional lateral type by 0.9K/W. This is because the light emitting layer of the flip chip crystal grain is closer to the heat-sink substrate, shortening the heat dissipation route, and thus lowering the thermal resistance value. For the total thermal resistance, the crystal grain structure has a lesser

  16. Washability characteristics of residual coals obtained from solvent extraction: studies towards developing cleaner coal technology

    Energy Technology Data Exchange (ETDEWEB)

    Giri, C.C.; Sharma, D.K. [Indian Institute of Technology, New Delhi (India). Centre for Energy Studies

    2004-07-01

    The washability characteristics of original Indian coals and solvent-extracted residual coals were studied by the float and sink technique. The following conclusions were drawn on the basis of the present study. Anthracene oil-extracted residual coals have lower percentage of reactions in the specific gravity range of 1.4 to 1.6 than the original coals, which indicates that the mineral matter is disassociated from the organic mass, and the anthracene oil-extracted residual coal is more suitable for washing than the original coal. The floatability behaviour of coal increases during NMP (N-methyl-2-pyrrolidone) extraction. This indicates that coal changes its washability character during NMP extractions. As during NMP extraction the surface area of coal increases by creating fissures in the matrix, the chemical leaching technique would be more suitable to remove the mineral matter in the residual coals. 12 refs., 3 figs., 2 tabs.

  17. Experimental determination of the heat transfer and cold storage characteristics of a microencapsulated phase change material in a horizontal tank

    International Nuclear Information System (INIS)

    Allouche, Yosr; Varga, Szabolcs; Bouden, Chiheb; Oliveira, Armando C.

    2015-01-01

    Highlights: • Cold storage characteristics in latent and sensible heat storage mediums were studied. • Thermo-physical characterization of the phase change material was carried out. • A non-Newtonian shear thickening behavior of the phase change material was observed. • An energy storage enhancement (53%) was observed in the latent heat storage medium. - Abstract: In the present paper, the performance of a microencapsulated phase change material (in 45% w/w concentration) for low temperature thermal energy storage, suitable for air conditioning applications is studied. The results are compared to a sensible heat storage unit using water. Thermo-physical properties such as the specific heat, enthalpy variation, thermal conductivity and density are also experimentally determined. The non-Newtonian shear-thickening behavior of the phase change material slurry is quantified. Thermal energy performance is experimentally determined for a 100 l horizontal tank. The heat transfer between the heat transfer fluid and the phase change material was provided by a tube-bundle heat exchanger inside the tank. The results show that the amount of energy stored using the phase change material is 53% higher than for water after 10 h of charging, for the same storage tank volume. It was found that the heat transfer coefficient between the phase change material and the tube wall increases during the phase change temperature range, however it remains smaller than the values obtained for water

  18. Comparative Analysis of the Principal Characteristics of Microsilica Obtained from Silicon Manufacture Wastes and Used in Concrete Production Technologies

    Science.gov (United States)

    Balabanov, V. B.; Putsenko, K. N.

    2017-11-01

    On the basis of the survey of foreign and domestic literature over the past 65 years devoted to the study of the properties and the technology of applying microsilica in the capacity of modifying additives to concretes. Microsilica obtained as a by-product from the waste of ferroalloy plants and from the plants involved in production of silicon compounds is discussed. Analysis of the principal characteristics of different types of microsilica obtained from different sources is conducted.

  19. Aerodynamic characteristics and heat radiation performance of sportswear fabrics

    Science.gov (United States)

    Koga, H.; Hiratsuka, M.; Ito, S.; Konno, A.

    2017-10-01

    Sports such as swimming, speed skating, and marathon are sports competing for time. In recent years, reduction of the fluid drag of sportswear is required for these competitions in order to improve the record. In addition, sweating and discomfort due to body temperature rise during competition are thought to affect competitor performance, and heat radiation performance is also an important factor for sportswear. The authors have measured fluid force drag by wrapping cloth around a cylinder and have confirmed their differences due to the roughness of the fabric surface, differences in sewing. The authors could be verified the drag can be reduced by the position of the wear stitch. This time, we measured the heat radiation performance of 14 types of cloths whose aero dynamic properties are known using cylinders which are regarded as human fuselages, and found elements of cloth with heat radiation performance. It was found to be important for raising the heat radiation performance of sportswear that the fabric is thin and flat surface processing.

  20. Heat transfer characteristics of breeding zone in TBM of KOREA

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seong Dae; Lee, Dong Won; Kim, Dong Jun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ahn, Mu-Young [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In South Korea, lithium, Helium cooled ceramic reflector (HCCR) test blanket module (TBM) has been designed to install in ITER and verify the tritium production and the heat extraction. Helium cooled ceramic reflector (HCCR) test blanket module (TBM) is composed of four sub-modules and a common back manifold (BM). The HCCR TBM is cooled by a high temperature helium coolant of 300 .deg. C. The breeder, a neutron multiplier and reflector are included in the HCCR TBM. TBM is essential device to verify the tritium production and the heat extraction. The continuous deuterium-tritium (D-T) reaction should occur in order to generate heat and neutrons. The generated neutrons will react with lithium which is breeder. The margin to the allowable temperature for the breeder have a little with the conceptual design model of HCCR-TBM. Some feasible methods was discussed to lower the temperature of the breeding zone. The contact resistance between the wall and pebble beds was main factor to determine the breeder temperature. The installation of the cooling fins was considered to reduce the heat transfer resistance between the wall and the pebble beds. Thermal-hydraulic analysis was performed.

  1. Experimental studies on heat transfer and thermal performance characteristics of thermosyphon solar water heating system with helical and Left-Right twisted tapes

    International Nuclear Information System (INIS)

    Jaisankar, S.; Radhakrishnan, T.K.; Sheeba, K.N.

    2011-01-01

    Research highlights: → Conventional solar heaters are inefficient due to poor convective heat transfer. → Twisted tapes improve the heat transfer rate in solar water heater system. → Increase in outlet water temperature by 15 o C through the use of twisted tapes. →Thermal performance of twisted tape collector is 19% more than plain tube system. → Reduces collector area (0.6 m 2 ) whereas area for conventional collector is 1 m 2 . -- Abstract: Experimental investigation of heat transfer, friction factor and thermal performance of thermosyphon solar water heater system fitted with helical and Left-Right twist of twist ratio 3 has been performed and presented. The helical twisted tape induces swirl flow inside the riser tubes unidirectional over the length. But, in Left-Right system the swirl flow is bidirectional which increases the heat transfer and pressure drop when compared to the helical system. The experimental heat transfer and friction factors characteristics are validated with theoretical equations and the deviation falls with in the acceptable limits. The results show that heat transfer enhancement in twisted tape collector is higher than the plain tube collector. Compared to helical and Left-Right twisted tape system of same twist ratio 3, maximum thermal performance is obtained for Left-Right twisted tape collector with increase in solar intensity.

  2. Effect of the medium characteristics and the heating and cooling rates on the nonisothermal heat resistance of Bacillus sporothermodurans IC4 spores.

    Science.gov (United States)

    Esteban, María-Dolores; Huertas, Juan-Pablo; Fernández, Pablo S; Palop, Alfredo

    2013-05-01

    In recent years, highly thermo-resistant mesophilic spore-forming bacteria belonging to the species Bacillus sporothermodurans have caused non-sterility problems in industrial sterilization processes. The aim of this research was to evaluate the effect of the heating medium characteristics (pH and buffer/food) on the thermal inactivation of B. sporothermodurans spores when exposed to isothermal and non-isothermal heating and cooling treatments and the suitability of non-linear Weibull and Geeraaerd models to predict the survivors of these thermal treatments. Thermal treatments were carried out in pH 3, 5 and 7 McIlvaine buffer and in a courgette soup. Isothermal survival curves showed shoulders that were accurately characterized by means of both models. A clear effect of the pH of the heating medium was observed, decreasing the D120 value from pH 7 to pH 3 buffer down to one third. Differences in heat resistance were similar, regardless of the model used and were kept at all temperatures tested. The heat resistance in courgette soup was similar to that shown in pH 7 buffer. When the heat resistance values obtained under isothermal conditions were used to predict the survival in the non-isothermical experiments, the predictions estimated the experimental data quite accurately, both with Weibull and Geeraerd models. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Emission characteristics of biodiesel obtained from jatropha seeds and fish wastes in a diesel engine

    Directory of Open Access Journals (Sweden)

    Bhaskar Kathirvelu

    2017-11-01

    Full Text Available The concept of waste recycling and energy recovery plays a vital role for the development of any economy. The reuse of fish waste and use of wasteland for cultivation of jatropha seeds have led to resource conservation and their use as blend with diesel as an alternative fuel to diesel engines has contributed to pollution reduction. In this work, the results of using blends of biodiesel obtained from jatropha seeds, fish wastes and diesel in constant speed diesel engines are presented. The experimental results show that both the blends can be used as fuels for diesel engine without any major modification in the engines. It is also seen that the carbon monoxide, unburned hydrocarbons and soot emissions are reduced at all loads for both the blends compared to diesel fuel while NOx emissions are observed to be slightly higher.

  4. Structure and characteristics of functional powder composite materials obtained by spark plasma sintering

    Science.gov (United States)

    Oglezneva, S. A.; Kachenyuk, M. N.; Kulmeteva, V. B.; Ogleznev, N. B.

    2017-07-01

    The article describes the results of spark plasma sintering of ceramic materials based on titanium carbide, titanium carbosilicide, ceramic composite materials based on zirconium oxide, strengthened by carbon nanostructures and composite materials of electrotechnical purpose based on copper with addition of carbon structures and titanium carbosilicide. The research shows that the spark plasma sintering can achieve relative density of the material up to 98%. The effect of sintering temperature on the phase composition, density and porosity of the final product has been studied. It was found that with addition of carbon nanostructures the relative density and hardness decrease, but the fracture strength of ZrO2 increases up to times 2. The relative erosion resistance of the electrodes made of composite copper-based powder materials, obtained by spark plasma sintering during electroerosion treatment of tool steel exceeds that parameter of pure copper up to times 15.

  5. Thermal characteristics of high-temperature R718 heat pumps with turbo compressor thermal vapor recompression

    International Nuclear Information System (INIS)

    Šarevski, Milan N.; Šarevski, Vasko N.

    2017-01-01

    Highlights: • High pressure ratio, high speed, transonic R718 centrifugal compressors. • High efficient industrial evaporators/concentrators with turbo thermal vapor recompression. • Utilization of waste heat from industrial thermal and processing systems. • R718 is an ideal refrigerant for the novel high-temperature industrial heat pumps. • Application of single-stage R718 centrifugal compressors. - Abstract: Characteristics of R718 centrifugal compressors are analyzed and range of their applications in industrial high-temperature heat pumps, district heating systems and geothermal green house heating systems are estimated. Implementation of turbo compressor thermal vapor recompression in industrial evaporating/concentrating plants for waste heat utilization results in a high energy efficiency and in other technical, economical and environmental benefits. A novel concept of turbo compression R718 heat pumps is proposed and an assessment of their thermal characteristics is presented for utilization of waste heat from industrial thermal plants and systems (boilers, furnaces, various technological and metallurgical cooling processes, etc.), and for applications in district heating and geothermal green house heating systems. R718 is an ideal refrigerant for the novel high-temperature turbo compression industrial heat pumps. Direct evaporation and condensation are advantages of the proposed system which lead to higher COP, and to simplification of the plant and lower cost.

  6. Determination of elastic mechanical characteristics of surface coatings from analysis of signals obtained by impulse excitation

    Science.gov (United States)

    Nyaguly, E.; Craştiu, I.; Deac, S.; Gozman-Pop, C.; Drăgănescu, G.; Bereteu, L.

    2018-01-01

    Most of the surface coatings are based on the synthetic polymers, which are substances composed from very large molecules that form tough, flexible, adhesive films when applied to surfaces. The other components of surface coverings materials are pigments that provide colour, opacity, gloss and other properties. Surface coatings are two-phase composite materials: constitute a polymer matrix on the one side, and on the other side of the pigments and additives dispersed in the matrix. Their role is not only aesthetically but also to ensure anticorrosive protection or even improve some mechanical properties of coated surfaces. In this paper it will follow, starting from the mechanical properties of the substrate, the metallic sheet in general, to determine the new properties of the assembly of substrate and the two coating layers, also the determination of mechanical properties of the layers. From the analysis of vibroacoustic signals obtained by the impulse excitation of the sample, one can determine the elasticity modulus. These results come to validate the results based on finite element analysis (FEA) of the same samples.

  7. Study of heat exchange characteristics of the Dalat Nuclear Reactor

    International Nuclear Information System (INIS)

    An, N.K.; Huy, N.Q.

    1989-01-01

    This report is presented some experimental data and related theoretical computations concerning the thermal exchange system under normal operating or accidental conditions from the thermodynamic point of view. In the normal operation, the reactor operates under safety condition T max fuel=96.2 degree C. Under LOFA condition, the heat exchage process is still realized, therefore, we should determine the allowable limits of the thermal regime at power and at shut down condition

  8. Heat Transfer and Pressure Drop Characteristics in Straight Microchannel of Printed Circuit Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Jang-Won Seo

    2015-05-01

    Full Text Available Performance tests were carried out for a microchannel printed circuit heat exchanger (PCHE, which was fabricated with micro photo-etching and diffusion bonding technologies. The microchannel PCHE was tested for Reynolds numbers in the range of 100‒850 varying the hot-side inlet temperature between 40 °C–50 °C while keeping the cold-side temperature fixed at 20 °C. It was found that the average heat transfer rate and heat transfer performance of the countercurrrent configuration were 6.8% and 10%‒15% higher, respectively, than those of the parallel flow. The average heat transfer rate, heat transfer performance and pressure drop increased with increasing Reynolds number in all experiments. Increasing inlet temperature did not affect the heat transfer performance while it slightly decreased the pressure drop in the experimental range considered. Empirical correlations have been developed for the heat transfer coefficient and pressure drop factor as functions of the Reynolds number.

  9. Thermophysical characteristics of plastic bottles as an element of water heat accumulators in solar greenhouses

    International Nuclear Information System (INIS)

    Khalimov, A. G.; Khairiddinov, B. Eh.; Kim, V. D.; Khalimov, G. G.

    2012-01-01

    This article considers the thermophysical and granulometric characteristics of polyethylene terephthalate (PET) plastic bottles filled with water. The given figures allow one to conduct calculations of thermal plastic bottles as heat storage elements for solar greenhouses. (author)

  10. Performance Study on The heat-transfer characteristic of a LVG in Different Sizes

    Science.gov (United States)

    Wei, Jin

    2018-03-01

    In this paper, a new type of LVG were tested and the results show that it has good heat transfer function and pressure drop characteristic. In order to obtain the related functional influences of the newly LVG in different parameters, a three-dimensional numerical simulation was made. The result indicates that the perturbation effect of the same LVG at a lower current speed is better than the effect of a high speed. Inorder to avoid the breakdown of the vortex very quickly, the LVG sizes should be decreased appropriately when the current speed is high; to generate effective longitudinal vortex, the LVG must have large enough size and width, when the ratio of width to height is H=2, the effect is better than H=1; it is ideal for the attack angle of LVG in low speed zone to take Forty five degree angle.

  11. The inaccuracy of heat transfer characteristics for non-insulated and insulated spherical containers neglecting the influence of heat radiation

    International Nuclear Information System (INIS)

    Wong, King-Leung; Salazar, Jose Luis Leon; Prasad, Leo; Chen, Wen-Lih

    2011-01-01

    In this investigation, the differences of heat transfer characteristics for insulated and non-insulated spherical containers between considering and neglecting the influence of heat radiation are studied by the simulations in some practical situations. It is found that the heat radiation effect cannot be ignored in conditions of low ambient convection heat coefficients (such ambient air) and high surface emissivities, especially for the non-insulated and thin insulated cases. In most practical situations when ambient temperature is different from surroundings temperature and the emissivity of insulation surface is different from that of metal wall surface, neglecting heat radiation will result in inaccurate insulation effect and heat transfer errors even with very thick insulation. However, the insulation effect considering heat radiation will only increase a very small amount after some dimensionless insulated thickness (such insulation thickness/radius ≥0.2 in this study), thus such dimensionless insulated thickness can be used as the optimum thickness in practical applications. Meanwhile, wrapping a material with low surface emissivity (such as aluminum foil) around the oxidized metal wall or insulation layer (always with high surface emissivity) can achieve very good insulated effect for the non-insulated or thin insulated containers.

  12. Cold Heat Release Characteristics of Solidified Oil Droplet-Water Solution Latent Heat Emulsion by Air Bubbles

    Science.gov (United States)

    Inaba, Hideo; Morita, Shin-Ichi

    The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.

  13. Numerical analysis of cavitating flow characteristics in impeller of residual heat removal pump

    NARCIS (Netherlands)

    Hong, Feng; Yuan, Jianping; Zhou, Banglun

    2016-01-01

    In order to investigate internal cavitating flow characteristics of the impeller in residual heat removal pumps, the three-dimensional cavitating flow in a residual heat removal model pump is numerically calculated by using the homogeneous mixture cavitation model based on the Rayleigh-Plesset

  14. Performance Characteristics of a Modularized and Integrated PTC Heating System for an Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Yoon Hyuk Shin

    2015-12-01

    Full Text Available A modularized positive temperature coefficient heating system has controller-integrated heater modules. Such a heating system that uses a high-voltage power of 330 V was developed in the present study for use in electric vehicles. Four heater modules and one controller with an input power of 5.6 kW were integrated in the modularized system, which was designed for improved heating power density and light weight compared to the conventional heating system, in which the controller is separated. We experimentally investigated the performance characteristics, namely, the heating capacity, energy efficiency, and pressure drop, of a prototype of the developed heating system and found it to have satisfactory performance. The findings of this study will contribute to the development of heating systems for electric vehicles.

  15. Hot-gas-side heat transfer characteristics of subscale, plug-nozzle rocket calorimeter chamber

    Science.gov (United States)

    Quentmeyer, Richard J.; Roncace, Elizabeth A.

    1993-01-01

    An experimental investigation was conducted to determine the hot-gas-side heat transfer characteristics for a liquid-hydrogen-cooled, subscale, plug-nozzle rocket test apparatus. This apparatus has been used since 1975 to evaluate rocket engine advanced cooling concepts and fabrication techniques, to screen candidate combustion chamber liner materials, and to provide data for model development. In order to obtain the data, a water-cooled calorimeter chamber having the same geometric configuration as the plug-nozzle test apparatus was tested. It also used the same two showerhead injector types that were used on the test apparatus: one having a Rigimesh faceplate and the other having a platelet faceplate. The tests were conducted using liquid oxygen and gaseous hydrogen as the propellants over a mixture ratio range of 5.8 to 6.3 at a nominal chamber pressure of 4.14 MPa abs (600 psia). The two injectors showed similar performance characteristics with the Rigimesh faceplate having a slightly higher average characteristic-exhaust-velocity efficiency of 96 percent versus 94.4 percent for the platelet faceplate. The throat heat flux was 54 MW/m(sup 2) (33 Btu/in.(sup 2)-sec) at the nominal operating condition, which was a chamber pressure of 4.14 MPa abs (600 psia), a hot-gas-side wall temperature of 730 K (1314 R), and a mixture ratio of 6.0. The chamber throat region correlation coefficient C(sub g) for a Nusselt number correlation of the form Nu =C(sub g)Re(sup 0.8)Pr(sup 0.3) averaged 0.023 for the Rigimesh faceplate and 0.026 for the platelet faceplate.

  16. Heat balance characteristics and water use efficiency of soybean community

    International Nuclear Information System (INIS)

    Lee, Y.S.; Im, J.N.

    1990-01-01

    A field experiment was conducted to study seasonal evapotranspiration above soybean canopy and its relationship with dry matter production by the Bowen ratio-energy balance method. The soybean ''Paldalkong'' was sown with the space of 40 * 10 cm at Suwon on May 27, 1988. The daily net radiation ranged from 59 to 76 percents of the total shortwave radiation under cloudless conditions, which was lower than cloud overcast condition with record 63 to 83 percents. The latent heat flux under overcast condition was sometimes larger than the sum of net radiation, implying transportation of energy by advection of ambient air

  17. Numerical analysis on the condensation heat transfer and pressure drop characteristics of the horizontal tubes of modular shell and tube-bundle heat exchanger

    International Nuclear Information System (INIS)

    Ko, Seung Hwan; Park, Hyung Gyu; Kim, Charn Jung; Park, Byung Kyu

    2001-01-01

    A numerical analysis of the heat and mass transfer and pressure drop characteristics in modular shell and tube bundle heat exchanger was carried out. Finite concept method based on FVM and κ-ε turbulent model were used for this analysis. Condensation heat transfer enhanced total heat transfer rate 4∼8% higher than that of dry heat exchanger. With increasing humid air inlet velocity, temperature and relative humidity, and with decreasing heat exchanger aspect ratio and cooling water velocity, total heat and mass transfer rate could be increased. Cooling water inlet velocity had little effect on total heat transfer

  18. Vanadium and heat treatments effect on elastic characteristics of niobium

    International Nuclear Information System (INIS)

    Vasil'eva, E.V.; Tret'yakov, V.I.; Prokoshkin, D.A.; Pustovalov, V.A.

    1975-01-01

    The effect of vanadium content and of heat treatment conditions on the elastic properties of niobium at temperatures of 20 to 800 deg C was studied. Nb-V alloys were produced by binary vacuum remelting. The Nb-V alloys have been then subjected to thermal treatment. The total degree of deformation amounts to about 95%. The specimens were tested with a view to determine their microhardness, specific electric resistance, elasticity limit and modulus of elasticity. The elastic limit of niobium rises when alloyed with vanadium. With the increase of vanadium content the elastic limit of the alloy becomes greater. Pre-crystallization annealing at 600 - 700 deg C considerably increases the elastic limit, which is explained by development of the thermally activated processes leading to a decrease of dislocation mobility and thereby to a strengthening of the alloy

  19. Some conclusions obtained from the thermo-hydraulic behavior analysis of the nuclear power plant Atucha I, in case of loss of coolant accident with second heat sink

    International Nuclear Information System (INIS)

    Ventura, Mirta A.

    2003-01-01

    This paper is based on the recompilation, analysis and elaboration of the results of the operator (NA-SA), in the framework of the Atucha I Second Heat Sink project. The results have been compared with those obtained for the same power plant without second heat sink. The conclusions of the work permit the establishment of the operation rules of the plant. (author)

  20. Study of heat transfer and pressure drop characteristics of air heat exchanger using PCM for free cooling applications

    Directory of Open Access Journals (Sweden)

    Kalaiselvam Sivakumar

    2016-01-01

    Full Text Available Free cooling is the process of storing the cool energy available in the night ambient air and using it during the day. The heat exchanger used in this work is a modular type which is similar to the shell and tube heat exchanger. The shell side is filled with Phase Change Materials (PCM and air flow is through the tubes in the module. The modules of the heat exchanger are arranged one over other with air spacers in between each module. The air space provided in between the module in-creases the retention time of the air for better heat transfer. Transient Computational Fluid Dynamics modeling is carried out for single air passage in a modular heat exchanger. It shows that the PCM phase transition time in the module in which different shape of fins is adopted. The module with rectangular fins has 17.2 % reduction in solidification compared with the plain module. Then steady state numerical analysis is accomplished to the whole module having the fin of high heat transfer, so that pressure drop, flow and thermal characteristics across the module and the air spacers are deter-mined for various air inlet velocities of 0.4 to 1.6 m/s. To validate the computational results, experiments are carried out and the agreement was found to be good.

  1. Characteristics of an ammonia/lithium nitrate double effect heat pump-transformer

    International Nuclear Information System (INIS)

    Heard, C.L.; Rivera, W.; Best, R.

    2016-01-01

    Highlights: • The ammonia/lithium nitrate cycle is a little less efficient than the water/lithium bromide cycle. • Ratios of useful heat delivered to driving heat of nearly four are shown to be achievable. • Operating characteristics of a NH3/LiNO3 double effect absorption heat pump-transformer. - Abstract: The modelled operating characteristics of an ammonia/lithium nitrate double effect absorption heat pump-transformer (Type III absorption heat pump) are presented and compared to other working pair options and absorption heat pump cycles. Heat and mass balance equations are given. The effect of sub-optimal cycle design is shown on cycle thermal efficiency and solution pump power. It is shown that the ammonia/lithium nitrate working pair would achieve a performance a little less efficient than a water/lithium bromide system but is somewhat more tolerant of less than optimum operating conditions with respect to cycle thermal efficiency and solution pump power. Ratios of useful heat delivered to driving heat of nearly four are shown to be achievable with this system.

  2. The impact of temporal variability of excess sludge characteristics on the effects obtained in the process of its ultrasonic disintegration.

    Science.gov (United States)

    Tytła, Malwina; Zielewicz, Ewa

    2017-09-13

    This paper aimed to indicate the characteristics of excess sludge, which have the greatest impact on the effects obtained during its ultrasonic disintegration (UD). The direct and technological effects observed after sludge disintegration and anaerobic digestion (AD) depend on the factors affecting the quality of its matrix and simply on the parameters of a disintegrator. Sludge samples originate from a Central Waste Water Treatment Plant in Gliwice, and were collected after mechanical thickening by a monthly period. This approach allowed to observe the temporal changes of sludge characteristics, in a continuous manner. To evaluate the achieved disintegration effects, the following indicators were used: degree of disintegration (DD COD ) and the author's indicators describing the direct and technological effects of UD (ID i , IT i , IT d ), based on the changes in the sludge characteristics. Disintegration was carried out by means of an ultrasonic device equipped with a thin sonotrode. AD was conducted under mesophilic conditions for 20 days. Statistical analysis confirmed that the most important parameters of sludge, which determine obtained effects, were total and volatile solids, capillary suction time, concentration of chemical oxygen demand and pH value. The investigations have also showed that the increase in sludge temperature during its disintegration has a significant impact on the magnitude of other effects obtained in the process.

  3. Drying characteristics of rough rice by far-infrared radiation heating

    International Nuclear Information System (INIS)

    Matsuoka, T.

    1990-01-01

    The relationship between the heat radiation characteristics of a far-infrared radiation heater and the drying characteristics of rough rice was investigated to determine the basic data required for utilization of far-infrared rays for drying rough rice. Results of investigations are discussed in detail

  4. Effect of heating and pore water salinity on the swelling characteristics of bentonite buffer

    International Nuclear Information System (INIS)

    Dhawan, Sarita; Rao, M. Sudhakar

    2010-01-01

    Document available in extended abstract form only. Changes in swell potential of bentonite-sand mixture as a function of temperature and pore water salinity were measured. Bentonite dried at 105 deg. C and sand was mixed in 50:50 ratio by weight for study. The bentonite sand mix was compacted to 1.83 Mg/m 3 dry density and 13.8% water content (mixed with distilled water) obtained from Modified proctor compaction test for all test conditions. For the first series, the mix was prepared using distilled water as molding fluid. The compacted samples were dried at temperatures 50 deg. C and 80 deg. C for time periods 2 to 45 days. Dried samples were assembled in oedometer cells and allowed to swell under load of 6.25 kPa. In second series, bentonite sand mixes were prepared with 1000 ppm Na, 1000 ppm K, 1000 ppm Ca and 1000 ppm Mg solutions using chloride salts to achieve water content of 13.8%. The mixes were then compacted and dried at 80 deg. C for 15 days and allowed to swell in oedometer assembly. In third series of experiments, bentonite sand mix were compacted with distilled water as molding fluid and heated at 80 deg. C for 15 days. The dried samples were then swollen inundating with solutions simulating less saline granitic ground water and a moderately saline groundwater. The swell behavior is compared with samples without heating treatment. For samples prepared with distilled water and heated, the swell potential reduced up to 10-28% on heating compared to sample without any heating. The swell reduction varied depending on temperature and time period. The volumetric shrinkage varied from 1.4 to 3.3% of original volume of compacted sample on heating. Addition of sand was found effective in controlling shrinkage caused by heating. For samples prepared with salt solutions with no heating and inundated with distilled water for swell, the swell potential reduced from 12-20% compared to sample mixed and inundated with distilled water. The reduction in swell

  5. Study on heat transfer characteristics in a mixing tee pipe to evaluate for thermal fatigue

    International Nuclear Information System (INIS)

    Miyoshi, Koji; Nakamura, Akira; Utanohara, Yoichi

    2016-01-01

    Thermal fatigue racking may initiate at a tee pipe where high and low temperature fluids flow in from different directions and mix. Thermal stress fluctuations are caused by movement of a hot spot on the pipe inner surface. It is important to investigate the heat transfer from the fluid to the structure around the hot spot. The heat transfer characteristic in the mixing tee pipe was investigated by tests in this study. The unsteady heat transfer coefficients around the hot spot were estimated with the fluid and wall temperature, which were measured with thermocouples. The estimated heat transfer coefficient varied from 1.2 to 3.5 times of the steady state heat transfer coefficient. The heat transfer coefficient was 2.9 times of the steady state value at the position for the maximum stress fluctuation, which was calculated with the measured wall temperature distribution. (author)

  6. Influence of Actively Controlled Heat Release Timing on the Performance and Operational Characteristics of a Rotary Valve, Acoustically Resonant Pulse Combustor

    KAUST Repository

    Lisanti, Joel; Roberts, William L.

    2017-01-01

    The influence of heat release timing on the performance and operational characteristics of a rotary valve, acoustically resonant pulse combustor is investigated both experimentally and numerically. Simulation results are obtained by solving the quasi-1D Navier-Stokes equations with forced volumetric heat addition. Experimental efforts modify heat release timing through modulated fuel injection and modification of the fluid dynamic mixing. Results indicate that the heat release timing has a profound effect on the operation and efficiency of the pulse combustor and that this timing can be difficult to control experimentally.

  7. Influence of Actively Controlled Heat Release Timing on the Performance and Operational Characteristics of a Rotary Valve, Acoustically Resonant Pulse Combustor

    KAUST Repository

    Lisanti, Joel

    2017-01-05

    The influence of heat release timing on the performance and operational characteristics of a rotary valve, acoustically resonant pulse combustor is investigated both experimentally and numerically. Simulation results are obtained by solving the quasi-1D Navier-Stokes equations with forced volumetric heat addition. Experimental efforts modify heat release timing through modulated fuel injection and modification of the fluid dynamic mixing. Results indicate that the heat release timing has a profound effect on the operation and efficiency of the pulse combustor and that this timing can be difficult to control experimentally.

  8. Research on heat transfer characteristic of crude oil during the tubular heating process in the floating roof tank

    Directory of Open Access Journals (Sweden)

    Jian Zhao

    2017-09-01

    Full Text Available By means of finite volume method, the heat transfer characteristic of crude oil under the tubular heating in the floating roof tank is investigated by numerical simulation. The evolution of temperature profile and its relationship with the flow pattern is presented in detail. A noticeable finding is that there exists the transformation of the flow pattern which affects the temperature profile apparently during the heating process. Special concern is taken on the evolution of temperature distribution on the interface between oil and the inner wall of the tank. The temperature profile on the top wall, sidewall and base wall of the tank is investigated. It is concluded that the plume induced by natural convection takes most responsibility for the formation of temperature field in the tank. The second factor is the boundary condition of the tank.

  9. Heat transfer characteristics of liquid-gas Taylor flows incorporating microencapsulated phase change materials

    International Nuclear Information System (INIS)

    Howard, J A; Walsh, P A

    2014-01-01

    This paper presents an investigation on the heat transfer characteristics associated with liquid-gas Taylor flows in mini channels incorporating microencapsulated phase change materials (MPCM). Taylor flows have been shown to result in heat transfer enhancements due to the fluid recirculation experienced within liquid slugs which is attributable to the alternating liquid slug and gas bubble flow structure. Microencapsulated phase change materials (MPCM) also offer significant potential with increased thermal capacity due to the latent heat required to cause phase change. The primary aim of this work was to examine the overall heat transfer potential associated with combining these two novel liquid cooling technologies. By investigating the local heat transfer characteristics, the augmentation/degradation over single phase liquid cooling was quantified while examining the effects of dimensionless variables, including Reynolds number, liquid slug length and gas void fraction. An experimental test facility was developed which had a heated test section and allowed MPCM-air Taylor flows to be subjected to a constant heat flux boundary condition. Infrared thermography was used to record high resolution experimental wall temperature measurements and determine local heat transfer coefficients from the thermal entrance point. 30.2% mass particle concentration of the MPCM suspension fluid was examined as it provided the maximum latent heat for absorption. Results demonstrate a significant reduction in experimental wall temperatures associated with MPCM-air Taylor flows when compared with the Graetz solution for conventional single phase coolants. Total enhancement in the thermally developed region is observed to be a combination of the individual contributions due to recirculation within the liquid slugs and also absorption of latent heat. Overall, the study highlights the potential heat transfer enhancements that are attainable within heat exchange devices employing MPCM

  10. Optimum performance characteristics of a solar-driven Stirling heat engine system

    International Nuclear Information System (INIS)

    Liao, Tianjun; Lin, Jian

    2015-01-01

    Graphical abstract: T–S diagram of the SHE cycle. - Highlights: • Based on Lagrange multiplier method, the optimal performance are investigated. • The energy balance between the absorber and the hot side of Stirling heat engine is considered. • The effects of major parameters on the optimal performance are investigated. - Abstract: A solar-driven Stirling heat engine system composed of a Stirling heat engine, a solar collector, and a heat sink is presented, in which the radiation and convection heat losses of the solar collector, the heat-leak between the thermal absorber and heat sink, the regenerative losses of the Stirling heat engine, and the energy balance between the thermal absorber and the high isothermal process of the Stirling heat engine are taken into consideration. Based on the irreversible thermodynamics and Lagrange multiplier method, the maximum power output and the corresponding optimal efficiency of the system are determined and the absorber temperature that maximizes the optimal system efficiency is calculated numerically. The influences of some system parameters such as the concentrating ratio, the volume ratio during the regenerative processes and irreversibilities of heat exchange processes on the optimal efficiency are analyzed in details. The results obtained here may provide a new idea to design practical solar-driven Stirling heat engine system

  11. Heat transfer and flow region characteristics study in a non-annular channel between rotor and stator

    Directory of Open Access Journals (Sweden)

    Nili-Ahmadabadi M.

    2012-01-01

    Full Text Available This paper will present the results of the experimental investigation of heat transfer in a non-annular channel between rotor and stator similar to a real generator. Numerous experiments and numerical studies have examined flow and heat transfer characteristics of a fluid in an annulus with a rotating inner cylinder. In the current study, turbulent flow region and heat transfer characteristics have been studied in the air gap between the rotor and stator of a generator. The test rig has been built in a way which shows a very good agreement with the geometry of a real generator. The boundary condition supplies a non-homogenous heat flux through the passing air channel. The experimental devices and data acquisition method are carefully described in the paper. Surface-mounted thermocouples are located on the both stator and rotor surfaces and one slip ring transfers the collected temperature from rotor to the instrument display. The rotational speed of rotor is fixed at three under: 300rpm, 900 rpm and 1500 rpm. Based on these speeds and hydraulic diameter of the air gap, the Reynolds number has been considered in the range: 4000Heat transfer and pressure drop coefficients are deduced from the obtained data based on a theoretical investigation and are expressed as a formula containing effective Reynolds number. To confirm the results, a comparison is presented with Gazley’s (1985 data report. The presented method and established correlations can be applied to other electric machines having similar heat flow characteristics.

  12. Regeneration characteristics of desiccant rotor with microwave and hot-air heating

    International Nuclear Information System (INIS)

    Kubota, Mitsuhiro; Hanada, Takuya; Yabe, Satoshi; Matsuda, Hitoki

    2013-01-01

    Microwave heating, because of its advantages of direct and rapid heating of materials, has the potential to be employed as a novel regeneration method of desiccant rotors in humidity conditioners. We proposed a combined regeneration process, which combines microwave heating and conventional hot-air heating. The system is expected to achieve high heating rate during an initial regeneration period by assisting water desorption using the additional energy of the microwave. In this study, the regeneration characteristics of a desiccant rotor were experimentally investigated under conditions of microwave heating, hot-air heating, and combined heating at various microwave powers and hot-air temperatures. The effectiveness of the combined regeneration was evaluated in terms of the regeneration ratio, the initial regeneration rate, the temperature distribution in the rotor, and finally in terms of the energy consumption. It was demonstrated that combined heating was effective at leveling non-uniform temperature distribution in the rotor. Combined heating achieved higher ratios and initial rates in regeneration compared to just microwave and hot-air heating. This result was obviously attributed to the additional input of microwave energy, resulting that average rotor temperature increased by microwave absorption of rotor. Moreover, it was also effective for enhancement of regeneration to level the temperature distribution in the rotor by combination of two heating methods with different heating mechanisms. Both the initial regeneration rate and the equilibrium regeneration ratio for combined heating were found to increase as the microwave power increased. A linear relationship was observed with respect to microwave power. From the viewpoint of energy consumption, it may be possible to apply combined and microwave heating to humidity control systems that switch between adsorption and regeneration in short cycle times, if the conversion and absorption efficiencies of the

  13. Characteristics of organoclays obtained from Paraibas's smectites; Caracteristicas de argilas organofilicas obtidas de esmectitas da Paraiba

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Cortes, G.R.; Almeida, A.; Esper, F.J.; Alves Junior, P.; Valenzuela-Diaz, F.R., E-mail: germac@usp.br [Universidade de Sao Paulo (PMT/EP/USP), Sao Paulo, SP (Brazil). Escola Politecnica. Dept. de Engenharia Meralurgica e de Materiais; Hennies, W.T. [Universidade de Sao Paulo (PMT/EP/USP), Sao Paulo, SP (Brazil). Escola Politecnica. Dept. de Engenharia de Minas e de Petroleo

    2011-07-01

    Organoclay (AO) applies in the industry due to its particular technical characteristics. They are used as rheological additives in drilling fluids for oil, by adding viscosity solutions in which it participates: in paints, adhesives, lubricants, cosmetics and others. Recently grows its use as reinforcing filler in structuring polymer nanocomposites. The organoclays are obtained by the modification with quaternary ammonium of smectites. This paper presents the characteristics of a organoclay product of modified smectite from the State of Paraiba by quaternary ammonium. These studies were done in the PMT-EPUSP - Metallurgical and Materials Engineering Dept. of the Polytechnic School, University of Sao Paulo. The paper presents the results of studies through the techniques of X-ray diffraction, thermal analysis, infrared spectroscopy Foster swelling in oils and organic solvents tests and Scanning Electronic Microscopy. (author)

  14. Heat Transfer Characteristics of the Supercritical CO{sub 2} Flowing in a Vertical Annular Channel

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Tae Ho; Bae, Yoon Yeong; Kim, Hwan Yeol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-05-15

    Heat transfer test facility, SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation), has been operated at KAERI for an investigation of the thermal-hydraulic characteristics of supercritical CO{sub 2} at several test sections with a different geometry. The loop uses CO{sub 2} because it has much lower critical pressure and temperature than those of water. Experimental study of heat transfer to supercritical CO{sub 2} in a vertical annular channel with and hydraulic diameter of 4.5 mm has been performed. CO{sub 2} flows downward through the annular channel simulating the downward-flowing coolant in a multi-pass reactor or water rod moderator in a single pass reactor. The heat transfer characteristics in a downward flow were analyzed and compared with the upward flow test results performed previously with the same test section at KAERI

  15. Heat Transfer Characteristics of the Supercritical CO2 Flowing in a Vertical Annular Channel

    International Nuclear Information System (INIS)

    Yoo, Tae Ho; Bae, Yoon Yeong; Kim, Hwan Yeol

    2010-01-01

    Heat transfer test facility, SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation), has been operated at KAERI for an investigation of the thermal-hydraulic characteristics of supercritical CO 2 at several test sections with a different geometry. The loop uses CO 2 because it has much lower critical pressure and temperature than those of water. Experimental study of heat transfer to supercritical CO 2 in a vertical annular channel with and hydraulic diameter of 4.5 mm has been performed. CO 2 flows downward through the annular channel simulating the downward-flowing coolant in a multi-pass reactor or water rod moderator in a single pass reactor. The heat transfer characteristics in a downward flow were analyzed and compared with the upward flow test results performed previously with the same test section at KAERI

  16. Flowing and heat transfer characteristics of turbulent flow in typical rod bundles at rolling motion

    International Nuclear Information System (INIS)

    Yan Binghuo; Yu Lei; Gu Hanyang

    2011-01-01

    The influence mechanism of rolling motion on the flowing and heat transfer characteristics of turbulent flow in typical four rod bundles was investigated with Fluent code. The flowing and heat transfer characteristics of turbulent flow in rod bundles can be affected by rolling motion. But the flowing similarity of turbulent flow in adiabatic and non-adiabatic can not be affected. If the rolling period is small, the radial additional force can make the parameter profiles, the turbulent flowing and heat transfer change greatly. At rolling motion, as the pitch to diameter ratio decreases, especially if it is less than 1.1, the flowing and heat transfer of turbulent flow at rolling motion change significantly. The variation of pitch to diameter ratio can change the profiles of secondary flow and turbulent kinetic energy in cross-section greatly. (authors)

  17. Heat Transfer Characteristics for an Upward Flowing Supercritical Pressure CO2 in a Vertical Annulus Passage

    International Nuclear Information System (INIS)

    Kang, Deog Ji; Kim, Sin; Kim, Hwan Yeol; Bae, Yoon Yeong

    2007-01-01

    Heat transfer experiments at a vertical annulus passage were carried out in the SPHINX(Supercritical Pressure Heat Transfer Investigation for NeXt Generation) to investigate the heat transfer behaviors of supercritical CO 2 . The collected test data are to be used for the reactor core design of the SCWR (SuperCritical Water-cooled Reactor). The mass flux was in the range of 400 ∼1200 kg/m 2 s and the heat flux was chosen up to 150 kW/m 2 . The selected pressures were 7.75 and 8.12 MPa. The heat transfer data were analyzed and compared with the previous tube test data. The test results showed that the heat transfer characteristics were similar to those of the tube in case of a normal heat transfer mode and degree of heat transfer deterioration became smaller than that in the tube. Comparison of the experimental heat transfer coefficients with the predicted ones by the existing correlations showed that there was not a distinct difference between the correlations

  18. Spray characteristics and spray cooling heat transfer in the non-boiling regime

    International Nuclear Information System (INIS)

    Cheng, Wen-Long; Han, Feng-Yun; Liu, Qi-Nie; Fan, Han-Lin

    2011-01-01

    Spray cooling is an effective method for dissipating high heat fluxes in the field of electronics thermal control. In this study, experiments were performed with distilled water as a test liquid to study the spray cooling heat transfer in non-boiling regime. A Phase Doppler Anemometry (PDA) was used to study the spray characteristics. The effects of spray flow rate, spray height, and inlet temperature on spray cooling heat transfer were investigated. It was found that the parameters affect heat transfer of spray cooling in non-boiling regime by the spray characteristics and working fluid thermophysical properties. Then the corresponding droplet axial velocity and Sauter mean diameter (SMD) were successfully correlated with mean absolute error of 15%, which were based upon the orifice diameter, the Weber and Reynolds numbers of the orifice flow prior to liquid breakup, dimensionless spray height and spray cross-section radius. The heat transfer in non-boiling regime was correlated with a mean absolute error of 7%, which was mainly associated with the working fluid thermophysical properties, the Weber and Reynolds numbers hitting the heating surface, dimensionless heating surface temperature and diameter. -- Highlights: → The spray flow rate, spray height, and inlet temperature affect heat transfer of spray cooling in non-boiling regime by the spray characteristics and the working fluid thermophysical properties. → Then the corresponding droplet axial velocity and Sauer mean diameter (SMD) were successfully correlated with mean absolute error of 15%. → The heat transfer in non-boiling regime was correlated with a mean absolute error of 7%.

  19. Cluster analysis of residential heat load profiles and the role of technical and household characteristics

    DEFF Research Database (Denmark)

    Carmo, Carolina; Christensen, Toke Haunstrup

    2016-01-01

    of the temporality of the energy demand is needed. This paper contributes to this by focusing on the daily load profiles of energy demand for heating of Danish dwellings with heat pumps. Based on hourly recordings from 139 dwellings and employing cluster and regression analysis, the paper explores patterns...... (typologies) in daily heating load profiles and how these relate to socio-economic and technical characteristics of the included households. The study shows that the load profiles vary according to the external load conditions. Two main clusters were identified for both weekdays and weekends and across load...

  20. Thermal degradation characteristics and products obtained after pyrolysis of specific polymers found in Waste Electrical and Electronic Equipment

    Institute of Scientific and Technical Information of China (English)

    Evangelia C.Vouvoudi; Aristea T.Rousi; Dimitris S.Achilias

    2017-01-01

    Modern societies strongly support the recycling practices over simple waste accumulation due to environmental harm caused.In the framework of sustainable recycling of plastics from WEEE,pyrolysis is proposed here as a means of obtaining secondary value-added products.The aim of this study was to investigate the thermal degradation and the products obtained after pyrolysis of specific polymers found in the plastic part of WEEE,using thermogravimetric analysis and a pyrolizer equipped with a GC/MS.Polymers studied include ABS,HIPS,PC and a blend having a composition similar to that appearing in WEEE.It was found that,PC shows greater heat endurance compared to the other polymers,whereas ABS depolymerizes in three-steps.The existence of several polymers in the blend results in synergistic effects which decrease the onset and final temperature of degradation.Moreover,the fragmentation occurred in the pyrolyzer,at certain temperatures,resulted in a great variety of compounds,depending on the polymer type,such as monomers,aromatic products,phenolic compounds and hydrocarbons.The main conclusion from this investigation is that pyrolysis could be an effective method for the sustainable recycling of the plastic part of WEEE resulting in a mixture of chemicals with varying composition but being excellent to be used as fuel retrieved from secondary recycling sources.

  1. The effect of temperature and heating rate on char properties obtained from solar pyrolysis of beech wood.

    Science.gov (United States)

    Zeng, Kuo; Minh, Doan Pham; Gauthier, Daniel; Weiss-Hortala, Elsa; Nzihou, Ange; Flamant, Gilles

    2015-04-01

    Char samples were produced from pyrolysis in a lab-scale solar reactor. The pyrolysis of beech wood was carried out at temperatures ranging from 600 to 2000°C, with heating rates from 5 to 450°C/s. CHNS, scanning electron microscopy analysis, X-ray diffractometry, Brunauer-Emmett-Teller adsorption were employed to investigate the effect of temperature and heating rate on char composition and structure. The results indicated that char structure was more and more ordered with temperature increase and heating rate decrease (higher than 50°C/s). The surface area and pore volume firstly increased with temperature and reached maximum at 1200°C then reduced significantly at 2000°C. Besides, they firstly increased with heating rate and then decreased slightly at heating rate of 450°C/s when final temperature was no lower than 1200°C. Char reactivity measured by TGA analysis was found to correlate with the evolution of char surface area and pore volume with temperature and heating rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Heat Transfer Characteristics of CO2 at Supercritical Pressure in a Vertical Circular Tube

    International Nuclear Information System (INIS)

    Yoo, Tae Ho; Bae, Yoon Yong; Kim, Hwan Yeol

    2011-01-01

    At supercritical pressure, the physical properties of fluid change substantially and the heat transfer at a temperature similar to the critical or pseudo-critical temperature improves considerably: however, the heat transfer may deteriorate due to a sudden increase in the wall temperature at a certain condition of a mass and heat flux. In this study, the heat transfer rates in CO 2 flowing vertically upward and downward in a circular tube with a diameter of 4.57 mm under various conditions were calculated by measuring the temperature of the outer wall of the tube. The published heat transfer correlations(6,7) were analyzed by comparing their prediction values with 7,250 experimental data. By introducing a buoyancy parameter, a heat transfer correlation, which could be applied only to a normal heat transfer regime, was extended such that it can be applied to regime of heat transfer deterioration. The published criteria for heat transfer deterioration(9-12) were evaluated against the conditions obtained from the experiment in this study

  3. Numerical Analysis of Flow and Heat Transfer Characteristics of CO2 at Vapour and Supercritical Phases in Micro-Channels

    Directory of Open Access Journals (Sweden)

    Rao N.T.

    2016-01-01

    Full Text Available Supercritical carbon dioxide (CO2 has special thermal properties with better heat transfer and flow characteristics. Due to this reason, supercritical CO2 is being used recently in air-condition and refrigeration systems to replace non environmental friendly refrigerants. Even though many researches have been done, there are not many literatures for heat transfer and flow characteristics of supercritical CO2. Therefore, the main purpose of this study is to develop flow and heat transfer CFD models on two different phases; vapour and supercritical of CO2 to investigate the heat transfer characteristics and pressure drop in micro-channels. CO2 is considered to be in different phases with different flow pressures but at same temperature. For the simulation, the CO2 flow was assumed to be turbulent, nonisothermal and Newtonian. The numerical results for both phases are compared. From the numerical analysis, for both vapour and supercritical phases, the heat energy from CO2 gas transferred to water to attain thermal equilibrium. The temperature of CO2 at vapour phase decreased 1.78% compared to supercritical phase, which decreased for 0.56% from the inlet temperature. There was a drastic increase of 72% for average Nu when the phase changed from vapour to supercritical. The average Nu decreased rapidly about 41% after total pressure of 9.0 MPa. Pressure drop (ΔP increased together with Reynolds number (Re for vapour and supercritical phases. When the phase changed from vapour to supercritical, ΔP was increased about 26%. The results obtained from this study can provide information for further investigations on supercritical CO2.

  4. An experimental study on the heat transfer characteristics of a heat pipe heat exchanger with latent heat storage. Part II: Simultaneous charging/discharging modes

    International Nuclear Information System (INIS)

    Liu Zhongliang; Wang Zengyi; Ma Chongfang

    2006-01-01

    In this part of the paper, the performance of the simultaneous charging/discharging operation modes of the heat pipe heat exchanger with latent heat storage is experimentally studied. The experimental results show that the device may operate under either the fluid to fluid heat transfer with charging heat to the phase change material (PCM) or the fluid to fluid heat transfer with discharging heat from the PCM modes according to the initial temperature of the PCM. The melting/solidification curves, the performances of the heat pipes and the device, the influences of the inlet temperature and the mass flow rate of the cold water on the operation performance are investigated by extensive experiments. The experimental results also disclose that under the simultaneous charging/discharging operation mode, although the heat transfer from the hot water directly to the cold water may vary, it always takes up a major part of the total heat recovered by the cold water due to the very small thermal resistance compared with the thermal resistance of the PCM side. The melting/solidification processes taking place in the simultaneous charging/discharging operation are compared with those in the charging only and discharging only processes. By applying a simplified thermal resistance analysis, a criterion for predicting the exact operation modes was derived and used to explain the observed experimental phenomena

  5. Numerical study on heat transfer characteristics of liquid-fueled molten salt using OpenFOAM

    International Nuclear Information System (INIS)

    Jeong, Yeong Shin; Bang, In Cheol

    2017-01-01

    To pursue sustainability and safety enhancement of nuclear energy, molten salt reactor is regarded as a promising candidate among various types of gen-IV reactors. Besides, pyroprocessing, which treats molten salt containing fission products, should consider safety related to decay heat from fuel material. For design of molten salt-related nuclear system, it is required to consider both thermal-hydraulic characteristics and neutronic behaviors for demonstration. However, fundamental heat transfer study of molten salt in operation condition is not easy to be experimentally studied due to its large scale, high temperature condition as well as difficulties of treating fuel material. >From that reason, numerical study can have benefit to investigate behaviors of liquid-fueled molten salt in real condition. In this study, open source CFD package OpenFOAM was used to analyze liquid-fueled molten salt loop having internal heat source as a first step of research. Among various molten salts considered as a candidate of liquid fueled molten salt reactors, in this study, FLiBe was chosen as liquid salt. For simulating heat generation from fuel material within fluid flow, volumetric heat source was set for fluid domain and OpenFOAM solver was modified as fvOptions as customized. To investigate thermal-hydraulic behavior of molten salt, CFD model was developed and validated by comparing experimental results in terms of heat transfer and pressure drop. As preliminary stage, 2D cavity simulations were performed to validate the modeling capacity of modified solver of OpenFOAM by comparison with those of ANSYS-CFX. In addition, cases of external heat flux and internal heat source were compared to configure the effect of heat source setting in various operation condition. As a result, modified solver of OpenFOAM considering internal heat source have sufficient modeling capacity to simulate liquid-fueled molten salt systems including heat generation cases. (author)

  6. Crystallization of tetra-n-butyl ammonium bromide clathrate hydrate slurry and the related heat transfer characteristics

    International Nuclear Information System (INIS)

    Shi, X.J.; Zhang, P.

    2014-01-01

    Highlights: • Crystallization characteristics of TBAB CHS under different thermal conditions were clarified. • Overall heat transfer coefficients before and during the crystallization were obtained. • The crystallization characteristics of TBAB CHS mainly depend on the status of supercooled solution. • Dropping of TBAB CHS can accelerate the supercooling release and crystallization. - Abstract: Tetra-n-butyl ammonium bromide (TBAB) clathrate hydrate slurry (CHS) is a promising phase change material slurry for cold storage and transport in air-conditioning system. This slurry can be generated from the supercooled TBAB aqueous solution. In the present study, TBAB CHS was generated under different thermal conditions, i.e. different initial mass concentrations of TBAB aqueous solution and different supercooling degrees. The crystallization of TBAB CHS and the overall heat transfer coefficient under different thermal conditions were clarified. It was concluded that the crystallization characteristics of TBAB hydrate crystals mainly depended upon the thermal condition of the supercooled TBAB aqueous solution. In addition, the dropping of pre-produced TBAB CHS into supercooled TBAB aqueous solution could immediately induce the crystallization of TBAB hydrate crystals, and the initial type of TBAB hydrate crystals was only related to the status of the supercooled TBAB aqueous solution regardless of the type of the dropped TBAB CHS. Furthermore, the overall heat transfer coefficients before crystallization and during crystallization were also measured. It was found that more hydrate crystals would adhere to the vessel wall at larger supercooling degree and higher mass concentration of aqueous solution, which would deteriorate the heat transfer significantly. Moreover, images of TBAB hydrate crystals under different thermal conditions were recorded in order to help clarifying the crystallization characteristics

  7. Microstructural characteristics of low-temperature (1400°C sintered MgO obtained from seawater

    Directory of Open Access Journals (Sweden)

    Jakić Jelena

    2017-01-01

    Full Text Available The purpose of this study was to investigate the influence of a rinsing of Mg(OH2 precipitated from seawater by substoichiometric precipitation (80% precipitation and the addition of TiO2 on microstructural characteristics of the MgO obtained by sintering at low temperature (1400°C. The results of examination indicate that the method of rinsing of the magnesium hydroxide precipitate in the technological process of obtaining MgO from seawater significantly affects the chemical composition of samples, primarily with regard to the CaO and B2O3 content. The samples were doped with TiO2 to improve the evaporation of B2O3 and sintering of MgO samples that were characterized by XRD and SEM/EDS. These techniques confirmed the high purity of MgO samples obtained and the formation of secondary compounds in very small quantities that have a positive effect on the densification.

  8. Analysis of the use of waste heat obtained from coal-fired units in Organic Rankine Cycles and for brown coal drying

    International Nuclear Information System (INIS)

    Łukowicz, Henryk; Kochaniewicz, Andrzej

    2012-01-01

    The ever-increasing restrictions on greenhouse gas emissions have created a need for new energy technologies. One way to meet these new requirements is to optimise the efficiency of power units. This paper presents two energy technologies that, if used, will increase the efficiency of electricity generation. One of the most effective ways to improve the efficiency of brown coal-fired units is by drying the coal that is fed into the boiler. Here, we describe a technology that uses the waste heat obtained from exhaust gases. This paper also presents an analysis of the feasibility of and potential for using waste heat obtained from exhaust gases to feed Organic Rankine Cycles (ORCs). Several low-temperature working fluids were considered, which were selected based on properties that were best suited for these types of cycles. The impact of these working fluids on the efficiency and capacity of the ORC was also examined. The calculations for ORCs fed with waste heat obtained from exhaust gases from hard coal- and brown coal-fired boilers were compared. -- Highlights: ► We describe a technology that uses the waste heat obtained from exhaust gases. ► The impact of using different working fluids with a low boiling point is examined. ► We describe integrating the ORC with the power unit. ► The use of waste heat from boiler exhaust gases to dry brown coal is proposed. ► We demonstrate a possible increase in power unit efficiency.

  9. Proteome dataset of subcutaneous adipose tissue obtained from late pregnant dairy cows during summer heat stress and winter seasons

    Directory of Open Access Journals (Sweden)

    M. Zachut

    2017-06-01

    Full Text Available Adipose tissue has a central role in the regulation of metabolism in dairy cows, and many proteins expressed in this tissue are involved in metabolic responses to stress (Peinado et al., 2012 [1]. Environmental heat stress is one of the main stressors limiting production in dairy cattle (Fuquay, 1981; West, 2003 [2,3], and there is a complex interaction between heat stress and the transition period from late pregnancy to onset of lactation, which is manifested in heat-stressed late-gestation cows (Tao and Dahl, 2013 [4]. We recently defined the proteome of adipose tissue in peripartum dairy cows, identifying 586 proteins of which 18.9% were differentially abundant in insulin-resistant compared to insulin-sensitive adipose tissue (Zachut, 2015 [5]. That study showed that proteomic techniques constitute a valuable tool for identifying novel biomarkers in adipose tissue that are related to metabolic adaptation to stress in dairy cows. The objective of the present work was to examine the adipose tissue proteome under thermo-neutral or seasonal heat stress conditions in late pregnant dairy cows. We have collected subcutaneous adipose tissue biopsies from 10 late pregnant dairy cows during summer heat stress and from 8 late pregnant dairy cows during winter season, and identified and quantified 1495 proteins in the adipose tissues. This dataset of adipose tissue proteome from dairy cows adds novel information on the variety of proteins that are abundant in this tissue during late pregnancy under thermo-neutral as well as heat stress conditions. Differential abundance of 107 (7.1% proteins was found between summer and winter adipose. These results are discussed in our recent research article (Zachut et al., 2017 [6].

  10. Modifications of the urban heat island characteristics under exceptionally hot weather - A case study

    Science.gov (United States)

    Founda, Dimitra; Pierros, Fragiskos; Santamouris, Mathew

    2016-04-01

    Considerable recent research suggests that heat waves are becoming more frequent, more intense and longer in the future. Heat waves are characterised by the dominance of prolonged abnormally hot conditions related to synoptic scale anomalies, thus they affect extensive geographical areas. Heat waves (HW) have a profound impact on humans and they have been proven to increase mortality. Urban areas are known to be hotter than the surrounding rural areas due to the well documented urban heat island (UHI) phenomenon. Urban areas face increased risk under heat waves, due to the added heat from the urban heat island and increased population density. Given that urban populations keep increasing, citizens are exposed to significant heat related risk. Mitigation and adaptation strategies require a deep understanding of the response of the urban heat islands under extremely hot conditions. The response of the urban heat island under selected episodes of heat waves is examined in the city of Athens, from the comparison between stations of different characteristics (urban, suburban, coastal and rural). Two distinct episodes of heat waves occurring during summer 2000 were selected. Daily maximum air temperature at the urban station of the National Observatory of Athens (NOA) exceeded 40 0C for at least three consecutive days for both episodes. The intensity of UHI during heat waves was compared to the intensity under 'normal' conditions, represented from a period 'before' and 'after' the heat wave. Striking differences of UHI features between HW and no HW cases were observed, depending on the time of the day and the type of station. The comparison between the urban and the coastal station showed an increase of the order of 3 0C in the intensity of UHI during the HW days, as regards both daytime and nighttime conditions. The comparison between urban and a suburban (inland) station, revealed some different behaviour during HWs, with increases of the order of 3 0C in the nocturnal

  11. Characteristics of convective heat transport in a packed pebble-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Abdulmohsin, Rahman S., E-mail: rsar62@mst.edu [Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 400 West 11th Street/231 Schrenk Hall, Rolla, MO 65409-1230 (United States); Al-Dahhan, Muthanna H., E-mail: aldahhanm@mst.edu [Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 400 West 11th Street/231 Schrenk Hall, Rolla, MO 65409-1230 (United States); Department of Nuclear Engineering, 301 W. 14th St./222 Fulton Hall (United States)

    2015-04-01

    Highlights: • A fast-response heat transfer probe has been developed and used in this work. • Heat transport has been quantified in terms of local heat transfer coefficients. • The method of the electrically heated single sphere in packing has been applied. • The heat transfer coefficient increases from the center to the wall of packed bed. • This work advancing the knowledge of heat transport in the studied packed bed. - Abstract: Obtaining more precise results and a better understanding of the heat transport mechanism in the dynamic core of packed pebble-bed reactors is needed because this mechanism poses extreme challenges to the reliable design and efficient operation of these reactors. This mechanism can be quantified in terms of a solid-to-gas convective heat transfer coefficient. Therefore, in this work, the local convective heat transfer coefficients and their radial profiles were measured experimentally in a separate effect pilot-plant scale and cold-flow experimental setup of 0.3 m in diameter, using a sophisticated noninvasive heat transfer probe of spherical type. The effect of gas velocity on the heat transfer coefficient was investigated over a wide range of Reynolds numbers of practical importance. The experimental investigations of this work include various radial locations along the height of the bed. It was found that an increase in coolant gas flow velocity causes an increase in the heat transfer coefficient and that effect of the gas flow rate varies from laminar to turbulent flow regimes at all radial positions of the studied packed pebble-bed reactor. The results show that the local heat transfer coefficient increases from the bed center to the wall due to the change in the bed structure, and hence, in the flow pattern of the coolant gas. The findings clearly indicate that one value of an overall heat transfer coefficient cannot represent the local heat transfer coefficients within the bed; therefore, correlations are needed to

  12. Study on heat and mass transfer characteristics of humid air-flow in a fin bundle

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Hwi [Air-Conditioner Research Laboratory, LG Electronics, Seoul 153-082 (Korea); Koyama, Shigeru; Kuwahara, Ken [Department of Energy and Environmental Engineering, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Kwon, Jeong-Tae [Department of Mechanical Engineering, Hoseo University, Asan, Chungnam 336-795 (Korea); Park, Byung-Duck [School of Mechanical and Automotive Engineering, Kyungpook National University, Sangju, Gyeongbuk 742-711 (Korea)

    2010-11-15

    This paper deals with the heat and mass transfer characteristics of humid air-flow under frosting conditions. A slit fin bundle was used for the simulation of fins of a heat exchanger. The effects of the cooling block temperature, air humidity and air velocity on the frosting characteristics were experimentally investigated. The frosted mass was affected considerably by the cooling block temperature and air humidity. However, the effect of air velocity on it was not so large. The pressure drop was affected remarkably by all experimental parameters in this study. Local heat flux distribution and frost thickness distribution on each fin were predicted from the measured fin temperatures and the mass and energy conservation equations on the frost surface and inside the frost layer. (author)

  13. Controlling the Internal Heat Transfer Coefficient by the Characteristics of External Flows

    Science.gov (United States)

    Zhuromskii, V. M.

    2018-01-01

    The engineering-physical fundamentals of substance synthesis in a boiling apparatus are presented. We have modeled a system of automatic stabilization of the maximum internal heat transfer coefficient in such an apparatus by the characteristics of external flows on the basis of adaptive seeking algorithms. The results of operation of the system in the shop are presented.

  14. The effect of micro air movement on the heat and moisture characteristics of building constructions

    NARCIS (Netherlands)

    Schijndel, van A.W.M.

    2010-01-01

    The research focuses on the effect of air movement through building constructions. Although the typical air movement inside building constructions is quite small (velocity is of order ~10-5 m/s), this research shows the impact on the heat and moisture characteristics. The paper presents a case study

  15. The effect of micro air movement on the heat and moisture characteristics of building constructions

    NARCIS (Netherlands)

    Schijndel, van A.W.M.

    2008-01-01

    The research focuses on the effect of air movement through building constructions. Although the typical air movement inside building constructions is quite small (velocity is of order ~10-5 m/s), this research shows the impact on the heat and moisture characteristics. The paper presents a case study

  16. The relative influence of body characteristics on humid heat stress response

    NARCIS (Netherlands)

    Havenith, G.; Luttikholt, V. G.; Vrijkotte, T. G.

    1995-01-01

    The present study was designed to determine the relative importance of individual characteristics such as maximal oxygen uptake (VO2max), adiposity, DuBois body surface area (AD), surface to mass ratio (AD: mass) and body mass, for the individual's reaction to humid heat stress. For this purpose 27

  17. Field synergy characteristics in condensation heat transfer with non-condensable gas over a horizontal tube

    Directory of Open Access Journals (Sweden)

    Junxia Zhang

    2017-05-01

    Full Text Available Field synergy characteristics in condensation heat transfer with non-condensable gas (NCG over a horizontal tube were numerically simulated. Consequently, synergy angles between velocity and pressure or temperature gradient fields, gas film layer thickness, and induced velocity and shear stress on gas–liquid interface were obtained. Results show that synergy angles between velocity and temperature gradient fields are within 73.2°–88.7° and ascend slightly with the increment in mainstream velocity and that the synergy is poor. However, the synergy angle between velocity and pressure gradient fields decreases intensively with the increase in mainstream velocity at θ ≤ 30°, thereby improving the pressure loss. As NCG mass fraction increases, the gas film layer thickness enlarges and the induced velocity and shear stress on gas–liquid interface decreases. The synergy angles between velocity and temperature gradient fields increase, and the synergy angles between velocity and pressure gradient fields change at θ = 70°, decrease at θ 70°. When the horizontal tube circumference angle increases, the synergy angles between velocity and temperature or pressure gradient fields decrease, the synergy between velocity and pressure fields enhances, and the synergy between velocity and temperature fields degrades.

  18. A study on the effects of heated surface wettability on nucleation characteristics in subcooled flow boiling

    International Nuclear Information System (INIS)

    Kajihara, Tomoyuki; Kaiho, Kazuhiro; Okawa, Tomio

    2014-01-01

    Subcooled flow boiling plays an important role in boiling water reactors because it influences the heat transfer performance from fuel rods, two-phase flow stabilities, and neutron moderation characteristics. In the present study, flow visualization of water subcooled flow boiling in a vertical heated channel was carried out to investigate the mechanisms of void fraction development. The two surfaces of distinctly different contact angles were used as the heated surface to investigate the effect of the surface wettability. It was observed that with an increase in the wall heat flux, more nucleation sites were activated and larger bubbles were produced at low-frequency. It was considered that formation of these large bubbles primarily contributed to the void fraction development. (author)

  19. Effects of rolling on single-phase water forced convective heat transfer characteristics

    International Nuclear Information System (INIS)

    Guo Yanming; Gao Puzhen; Huang Zhen

    2010-01-01

    A series of single-phase forced circulation tests in a vertical tube with rolling motion were performed in order to investigate effects of rolling motion on thermal-hydraulic characteristics. The amplitudes of the rolling motion in the tests were 10 degree, 15 degree and 20 degree. The rolling periods were 7.5 s, 10 s, 15 s and 20 s. The Reynolds number was from 6000 to 15000. Heat transfer in the test tube is bated by the rolling motion. As the test-bed rolling more acutely, the heat transfer coefficient of the test tube becomes smaller when the mass flow rate in the test tube is a constant. The heat transfer coefficient calculated by the formula which is for stable state doesn't fit very well with that from experiments. At last a formula for calculating heat transfer in rolling motion was introduced. (authors)

  20. Photoactivity of brookite-rutile TiO(2) nanocrystalline mixtures obtained by heat treatment of hydrothermally prepared brookite

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Králová, Daniela

    2011-01-01

    Roč. 129, č. 3 (2011), s. 794-801 ISSN 0254-0584 R&D Projects: GA ČR GA203/08/0334 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40500505 Keywords : oxides * heat treatment * titania * photocatalysis Subject RIV: CA - Inorganic Chemistry Impact factor: 2.234, year: 2011

  1. Comparison among structural characteristics of Ce1-xCuxO2 nanocatalysts obtained by two methods of distinct synthesis

    International Nuclear Information System (INIS)

    Neiva, L.S.; Bispo, A.; Santos, P.T.A.; Costa, A.C.F.M.; Gama, L.; Mascarenhas, A.J.S.

    2009-01-01

    The objective this work is to synthesize nano catalysts Ce 1-x Cu x O 2 type by the synthesis methods of the combustion reaction and Pechini. The value of the concentration (x) of the element dope (Cu) varies between 0,1 and 0,5 mols. It intends evaluate that form the synthesis method influences in the physical structural characteristics of this material. nano catalysts were characterized by ray- X diffraction. The results showed nano catalysts formation with a formed structure for the most part by the phase CeO 2 , as it was expected, since this is the hostess matrix of the element dope (Cu). Nano catalysts obtained by the method Pechini presents crystallinity larger deg, according with patterns of ray-X. Thus, it was concluded that synthesis employee method the kind in the methodology, as well as the value of the concentration of the element dope has influence on the final structural characteristics of the developed material. (author)

  2. The structure and amphipathy characteristics of modified γ-zeins by SDS or alkali in conjunction with heating treatment.

    Science.gov (United States)

    Dong, Shi-Rong; Xu, Hong-Hua; Tan, Jun-Yan; Xie, Ming-Ming; Yu, Guo-Ping

    2017-10-15

    γ-Zein was modified by SDS or alkali combined with heating treatments in water and in 70% ethanol to change its amphipathic properties and explore the relationship between amphipathic characteristic and structure. γ-Zein water-dispersibility was dramatically increased via alkali or SDS combined with heating treatments, but their ethanol-dispersibilities were significantly different during ethanol evaporation. High both water-dispersibility and ethanol-dispersibility were found from alkali modified γ-zein while high water-dispersibility but low ethanol-dispersibility were obtained from SDS modified γ-zein, indicating that alkali modified γ-zein had better amphipathic characteristic compared with SDS modified γ-zein. Alkali modified γ-zein with higher amphipathic characteristic possessed higher structural inversion ability since it was easy to recover its native state as solvent changing from water to ethanol, contrary to SDS modified γ-zeins whose amphipathic characteristic was not improved. Moreover, the higher structural inversion ability of alkali modified γ-zein depended on the recovery capability of α-helix structure as solvent altering. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Development of surface wettability characteristics for enhancing pool boiling heat transfer

    International Nuclear Information System (INIS)

    Kim, Moo Hwan; Jo, Hang Jin

    2010-05-01

    For several centuries, many boiling experiments have been conducted. Based on literature survey, the characteristic of heating surface in boiling condition played as an important role which mainly influenced to boiling performance. Among many surface factor, the fact that wettability effect is significant to not only the enhancement of critical heat flux(CHF) but also the nucleate boiling heat transfer is also supported by other kinds of boiling experiments. In this regard, the excellent boiling performance (a high CHF and heat transfer performance) in pool boiling could be achieved through some favorable surface modification which satisfies the optimized wettability condition. To find the optimized boiling condition, we design the special heaters to examine how two materials, which have different wettability (e.g. hydrophilic and hydrophobic), affect the boiling phenomena. The special heaters have hydrophobic dots on hydrophilic surface. The contact angle of hydrophobic surface is 120 .deg. to water at the room temperature. The contact angle of hydrophilic surface is 60 .deg. at same conditions. To conduct the experiment with new surface condition, we developed new fabrication method and design the pool boiling experimental apparatus. Through this facility, we can the higher CHF on pattern surface than that on hydrophobic surface, and the higher boiling heat transfer performance on pattern surface than that on hydrophilic surface. Based on this experimental results, we concluded that we proposed new heating surface condition and surface fabrication method to realize the best boiling condition by modified heating surface condition

  4. Vibration characteristics of a vertical round tube according to heat transfer regimes

    International Nuclear Information System (INIS)

    Lee, Yong Ho; Kim, Dae Hun; Chang, Soon Heung; Baek, Won Pil

    2001-01-01

    This paper presents the results of an experimental work on the effects of boiling heat transfer regimes on the vibration. the experiment has been performed using an electrically heated veritcal round tube through which water flows at atmospheric pressure. Vibration characteristics of the heated tube are changed significantly by heat transfer regimes and flow patterns. For single-phase liquid convection, the rod vibrations are negligible. However, On the beginning of subcooled nucleate boiling at tube exit, vibration level becomes very large. As bubble departure is occurred at the nucleation site of heated surface, the vibration decrease to saturated boiling region where thermal equilibrium quality becomes 0.0 at tube exit. In saturated boiling region, vibration amplitude increase with exit quality up to certain maximum value then decreases. At liquid film dryout condition, vibration could be regarded as negligible, however, these results cannot be extended to DNB-type CHF mechanism. Frequency analysis results of vibration signals suggested that excitation sources be different with heat transfer regimes. This study would contribute to improve the understanding of the relationship between boiling heat transfer and FIV

  5. Characteristics of heat transfer fouling of thin stillage using model thin stillage and evaporator concentrates

    Science.gov (United States)

    Challa, Ravi Kumar

    The US fuel ethanol demand was 50.3 billion liters (13.3 billion gallons) in 2012. Corn ethanol was produced primarily by dry grind process. Heat transfer equipment fouling occurs during corn ethanol production and increases the operating expenses of ethanol plants. Following ethanol distillation, unfermentables are centrifuged to separate solids as wet grains and liquid fraction as thin stillage. Evaporator fouling occurs during thin stillage concentration to syrup and decreases evaporator performance. Evaporators need to be shutdown to clean the deposits from the evaporator surfaces. Scheduled and unscheduled evaporator shutdowns decrease process throughput and results in production losses. This research were aimed at investigating thin stillage fouling characteristics using an annular probe at conditions similar to an evaporator in a corn ethanol production plant. Fouling characteristics of commercial thin stillage and model thin stillage were studied as a function of bulk fluid temperature and heat transfer surface temperature. Experiments were conducted by circulating thin stillage or carbohydrate mixtures in a loop through the test section which consisted of an annular fouling probe while maintaining a constant heat flux by electrical heating and fluid flow rate. The change in fouling resistance with time was measured. Fouling curves obtained for thin stillage and concentrated thin stillage were linear with time but no induction periods were observed. Fouling rates for concentrated thin stillage were higher compared to commercial thin stillage due to the increase in solid concentration. Fouling rates for oil skimmed and unskimmed concentrated thin stillage were similar but lower than concentrated thin stillage at 10% solids concentration. Addition of post fermentation corn oil to commercial thin stillage at 0.5% increments increased the fouling rates up to 1% concentration but decreased at 1.5%. As thin stillage is composed of carbohydrates, protein, lipid

  6. Heat transfer and pressure drop characteristics of a plate heat exchanger using water based Al2O3 nanofluid for 30° and 60° chevron angles

    Science.gov (United States)

    Elias, M. M.; Saidur, R.; Ben-Mansour, R.; Hepbasli, A.; Rahim, N. A.; Jesbains, K.

    2018-04-01

    Nanofluid is a new class of engineering fluid that has good heat transfer characteristics which is essential to increase the heat transfer performance in various engineering applications such as heat exchangers and cooling of electronics. In this study, experiments were conducted to compare the heat transfer performance and pressure drop characteristics in a plate heat exchanger (PHE) for 30° and 60° chevron angles using water based Al2O3 nanofluid at the concentrations from 0 to 0.5 vol.% for different Reynolds numbers. The thermo-physical properties has been determined and presented in this paper. At 0.5 vol% concentration, the maximum heat transfer coefficient, the overall heat transfer coefficient and the heat transfer rate for 60° chevron angle have attained a higher percentage of 15.14%, 7.8% and 15.4%, respectively in comparison with the base fluid. Consequently, when the volume concentration or Reynolds number increases, the heat transfer coefficient and the overall heat transfer coefficient as well as the heat transfer rate of the PHE (Plate Heat Exchangers) increases respectively. Similarly, the pressure drop increases with the volume concentration. 60° chevron angle showed better performance in comparison with 30° chevron angle.

  7. Cold Heat Storage Characteristics of O/W-type Latent Heat Emulsion Including Continuum Phase of Water Treated with a Freezing Point Depression

    Science.gov (United States)

    Inaba, Hideo; Morita, Shin-Ichi

    This paper deals with flow and cold heat storage characteristics of the oil (tetradecane, C14H30, freezing point 278.9 K, Latent heat 229 kJ/kg)/water emulsion as a latent heat storage material having a low melting point. The test emulsion includes a water-urea solution as a continuum phase. The freezing point depression of the continuum phase permits enhancement of the heat transfer rate of the emulison, due to the large temperature difference between the latent heat storage material and water-urea solution. The velocity of emulsion flow and the inlet temperature of coolant in a coiled double tube heat exchanger are chosen as the experimental parameters. The pressure drop, the heat transfer coefficient of the emulsion in the coiled tube are measured in the temperture region over solid and liquid phase of the latent heat storage material. The finishing time of the cold heat storage is defined experimentally in the range of sensible and latent heat storage. It is clarified that the flow behavior of the emulsion as a non-Newtonian fluid has an important role in cold heat storage. The useful nondimentional correlation equations for the additional pressure loss coefficient, the heat transfer coefficient and the finishing time of the cold heat storage are derived in terms of Dean number and heat capacity ratio.

  8. A comparison of the thermal, emission and heat transfer characteristics of swirl-stabilized premixed and inverse diffusion flames

    Energy Technology Data Exchange (ETDEWEB)

    Zhen, H.S.; Leung, C.W.; Cheung, C.S. [Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong (China)

    2011-02-15

    Two swirl-stabilized flames, a premixed flame (PMF-s) and an inverse diffusion flame (IDF-s), were investigated experimentally in order to obtain information on their thermal, emission and heat transfer characteristics. The two flames, having different global air/fuel mixing mechanisms, were compared under identical air and fuel flow rates. Results showed that the two flames have similar visual features such as flame shape, size and structure because the Reynolds number and the swirl number which are important parameters representative of the aerodynamic characteristics of a swirling jet flow, are almost the same for the two flames. The minor dissimilarity in flame color and flame length indicates that the IDF-s is more diffusional. Both the PMF-s and IDF-s are stabilized by the internal recirculation zone (IRZ) and the IDF-s is more stable. Flame temperature is uniformly distributed in the IRZ due to the strong mixing caused by flow recirculation. The highest flame temperature is achieved at the main reaction zone and it is higher for the PMF-s due to more rapid and localized heat release. For the IDF-s, the thermal NO mechanism dominates the NO{sub x} formation. For the PMF-s, both the thermal and prompt mechanisms tend to play important roles in the global NO{sub x} emission under rich conditions. The comparison of EINO{sub x} and EICO shows that the PMF-s has lower level of NO{sub x} emission under lean combustion and lower level of CO emission under all conditions. The reason is that the air/fuel premixing in the PMF-s significantly enhances the mixedness of the supplied air/fuel mixture. The analysis of the behaviors of the impinging PMF-s and IDF-s heat transfer reveals that because the PMF-s has more rapid and localized heat release at the main reaction zone, the peak heat flux is higher than that of the IDF-s and the IDF-s has more uniform heating effect. A comparison of the overall heat transfer rates shows that, due to more complete combustion, the PMF

  9. A comparison of the thermal, emission and heat transfer characteristics of swirl-stabilized premixed and inverse diffusion flames

    International Nuclear Information System (INIS)

    Zhen, H.S.; Leung, C.W.; Cheung, C.S.

    2011-01-01

    Two swirl-stabilized flames, a premixed flame (PMF-s) and an inverse diffusion flame (IDF-s), were investigated experimentally in order to obtain information on their thermal, emission and heat transfer characteristics. The two flames, having different global air/fuel mixing mechanisms, were compared under identical air and fuel flow rates. Results showed that the two flames have similar visual features such as flame shape, size and structure because the Reynolds number and the swirl number which are important parameters representative of the aerodynamic characteristics of a swirling jet flow, are almost the same for the two flames. The minor dissimilarity in flame color and flame length indicates that the IDF-s is more diffusional. Both the PMF-s and IDF-s are stabilized by the internal recirculation zone (IRZ) and the IDF-s is more stable. Flame temperature is uniformly distributed in the IRZ due to the strong mixing caused by flow recirculation. The highest flame temperature is achieved at the main reaction zone and it is higher for the PMF-s due to more rapid and localized heat release. For the IDF-s, the thermal NO mechanism dominates the NO x formation. For the PMF-s, both the thermal and prompt mechanisms tend to play important roles in the global NO x emission under rich conditions. The comparison of EINO x and EICO shows that the PMF-s has lower level of NO x emission under lean combustion and lower level of CO emission under all conditions. The reason is that the air/fuel premixing in the PMF-s significantly enhances the mixedness of the supplied air/fuel mixture. The analysis of the behaviors of the impinging PMF-s and IDF-s heat transfer reveals that because the PMF-s has more rapid and localized heat release at the main reaction zone, the peak heat flux is higher than that of the IDF-s and the IDF-s has more uniform heating effect. A comparison of the overall heat transfer rates shows that, due to more complete combustion, the PMF-s has higher overall

  10. Structure and Output Characteristics of a TEM Array Fitted to a Fin Heat Exchanger

    Science.gov (United States)

    Zhang, Z.; Chen, L. N.; Chen, Z. J.; Xiao, G. Q.; Liu, Z. J.

    2015-06-01

    In the design of a thermoelectric generator, both the heat transfer area and the number of thermoelectric modules (TEMs) should be increased accordingly as the generator power increases; crucially, both aspects need to be coordinated. A kilowatt thermoelectric generator with a fin heat exchanger is proposed for use in a constant-speed diesel generator unit. Interior fins enhance convective heat transfer, whereas an exterior fin segment increases the heat transfer area. The heat transfer surface is double that of a plane heat exchanger, and the temperature field over the exterior fins is constrained to a one-dimensional distribution. Between adjoining exterior fins, there is a cooling water channel with trapezoid cross-section, enabling compact TEMs and cooling them. Hence, more TEMs are built as a series-parallel array of TEMs with lower resistance and more stable output current. Under nonuniform conditions, to prevent circulation and energy loss, bypass diodes and antidiodes are added. Experiments and numerical calculations show that, with matching and optimization of the heat exchanger and TEM array, a stable maximum output power is obtainable from the interior of the thermoelectric generator system, which can be connected to an external maximum power point tracking system.

  11. Research on the Heat Dissipation Characteristics of Lithium Battery Spatial Layout in an AUV

    Directory of Open Access Journals (Sweden)

    Zhaoyong Mao

    2016-01-01

    Full Text Available To meet the power demand requirements of autonomous underwater vehicles (AUVs, the power supply is generally composed of a large number of high-energy lithium battery groups. The lithium battery heat dissipation properties not only affect the underwater vehicle performance but also bring some security risks. Based on the widespread application of lithium batteries, lithium batteries in an AUV are taken as an example to investigate the heat dissipation characteristics of the lithium battery spatial layout in an AUV. With the aim of increasing the safety of lithium batteries, a model is developed for the heat transfer process based on the energy conservation equation, and the battery heat dissipation characteristics of the spatial layout are analyzed. The results indicate that the most suitable distance between the cells and the cross arrangement is better than the sequence arrangement in terms of cooling characteristics. The temperature gradient and the temperature change inside the cabin with time are primarily affected by the navigation speed, but they have little relationship with the environmental temperature.

  12. Characteristics of heat shrinkable high density polyethylene crosslinked by γ-irradiation

    International Nuclear Information System (INIS)

    Kang, Phil Hyun; Nho, Young Chang

    2001-01-01

    The effects of γ-irradiation on the crosslinking of high density polyethylene (HDPE) was investigated for the purpose of obtaining a suitable formulation for heat shrinkable materials. In this study the HDPE specimens were prepared by blending with cross linking agents and pressed into a 0.2 mm sheet at 180 .deg. C. γ-irradiation was conducted at 40 to 100 kGy in nitrogen. The heat shrinkable property and thermal mechanical property of the HDPE sheets have been investigated. It was found that the degree of crosslinking of the irradiated HDPE samples were increased with irradiation dose. Compared with the HDPE containing triallylisocyanurate, the HDPE containing trimethlol propane triacrylate shows a slight increase in crosslinking density. The heat transformation and dimension change of HDPE decreased with increasing radiation dose. The heat shrinkage of the samples increased with increasing annealing temperatures. The thermal resistance of HDPE increased upon the crosslinking of HDPE

  13. Heat transfer characteristics of coconut oil as phase change material to room cooling application

    Science.gov (United States)

    Irsyad, M.; Harmen

    2017-03-01

    Thermal comfort in a room is one of human needs in the workplace and dwellings, so that the use of air conditioning system in tropical countries is inevitable. This equipment has an impact on the increase of energy consumption. One method of minimizing the energy use is by using the phase change material (PCM) as thermal energy storage. This material utilizes the temperature difference between day and night for the storage and release of thermal energy. PCM development on application as a material for air cooling inlet, partitioning and interior needs to be supported by the study of heat transfer characteristics when PCM absorbs heat from ambient temperature. This study was conducted to determine the heat transfer characteristics on coconut oil as a phase change material. There are three models of experiments performed in this research. Firstly, an experiment was conducted to analyze the time that was needed by material to phase change by varying the temperature. The second experiment analyzed the heat transfer characteristics of air to PCM naturally convection. The third experiment analyzed the forced convection heat transfer on the surface of the PCM container by varying the air velocity. The data of experimental showed that, increasing ambient air temperature resulted in shorter time for phase change. At temperatures of 30°C, the time for phase change of PCM with the thickness of 8 cm was 1700 min, and it was stable at temperatures of 27°C. Increasing air temperature accelerated the phase change in the material. While for the forced convection heat transfer, PCM could reduce the air temperature in the range of 30 to 35°C at about 1 to 2°C, with a velocity of 1-3 m/s.

  14. Numerical study on the flow and heat transfer characteristics of slush nitrogen in a corrugated pipe

    Science.gov (United States)

    Li, Y. J.; Wu, S. Q.; Jin, T.

    2017-12-01

    Slush nitrogen has lower temperature, higher density and higher heat capacity than that of liquid nitrogen at normal boiling point. It is considered to be a potential coolant for high-temperature superconductive cables (HTS) that would decrease nitrogen consumption and storage cost. The corrugated pipe can help with the enhancement of heat transfer and flexibility of the coolants for HTS cables. In this paper, a 3-D Euler-Euler two-fluid model has been developed to study the flow and heat transfer characteristics of slush nitrogen in a horizontal helically corrugated pipe. By comparing with the empirical formula for pressure drop, the numerical model is confirmed to be effective for the prediction of slush nitrogen flow in corrugated pipes. The flow and heat transfer characteristics of slush nitrogen in a horizontal pipe at various working conditions (inlet solid fraction of 0-20%, inlet velocity of 0-3 m/s, heat flux of 0-12 kW/m2) have been analyzed. The friction factor of slush nitrogen is lower than that of subcooled liquid nitrogen when the slush Reynolds number is higher than 4.2×104. Moreover, the heat transfer coefficient of slush nitrogen flow in the corrugated pipe is higher than that of subcooled liquid nitrogen at velocities which is higher than that 1.76 m/s, 0.91 m/s and 0.55 m/s for slush nitrogen with solid fraction of 5%, 10% and 20%, respectively. The slush nitrogen has been confirmed to have better heat transfer performance and lower pressure drop instead of using liquid nitrogen flowing through a helically corrugated pipe.

  15. Numerical study on film cooling and convective heat transfer characteristics in the cutback region of turbine blade trailing edge

    Directory of Open Access Journals (Sweden)

    Xie Yong-Hui

    2016-01-01

    Full Text Available Gas turbine blade trailing edge is easy to burn out under the exposure of high-temperature gas due to its thin shape. The cooling of this area is an important task in gas turbine blade design. The structure design and analysis of trailing edge is critical because of the complexity of geometry, arrangement of cooling channels, design requirement of strength, and the working condition of high heat flux. In the present paper, a 3-D model of the trailing edge cooling channel is constructed and both structures with and without land are numerically investigated at different blowing ratio. The distributions of film cooling effectiveness and convective heat transfer coefficient on cutback and land surface are analyzed, respectively. According to the results, it is obtained that the distributions of film cooling effectiveness and convective heat transfer coefficient both show the symmetrical characteristics as a result of the periodic structure of the trailing edge. The increase of blowing ratio significantly improves the film cooling effectiveness and convective heat transfer coefficient on the cutback surface, which is beneficial to the cooling of trailing edge. It is also found that the land structure is advantageous for enhancing the streamwise film cooling effectiveness of the trailing edge surface while the film cooling effectiveness on the land surface remains at a low level. Convective heat transfer coefficient exhibits a strong dependency with the blowing ratio, which suggests that film cooling effectiveness and convective heat transfer coefficient must be both considered and analyzed in the design of trailing edge cooling structure.

  16. Study on the natural convection heat transfer characteristics in the air duct

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. K.; Lee, Y. B.; Choi, S. K.; Hwang, J. S.; Nam, H. Y. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    Temperature distribution measurements in the mockup apparatus of reactor vessel were performed to determine the effective thermal conductivity of porous media with different geometry and to obtain the experimental data for the heat transfer processes by natural convection occurring in the air duct. The temperature distributions at four separated sections with different arrangements of porous media have different slopes according to the geometrical configuration. From the measured temperature distribution, effective thermal conductivity have been derived using the least square fitting method. The test at air duct was performed to the high heat removal at 3.4kW/m{sup 2} by the natural convection from the outer wall to the air. And also the temperature distributions in the sir duct agree well with the 1/7th power-law turbulent temperature distribution. The obtained heat transfer data have been compared with the Shin`s and Sieger`s correlations. 10 refs., 6 figs. (Author)

  17. Study on the natural convection heat transfer characteristics in the air duct

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y K; Lee, Y B; Choi, S K; Hwang, J S; Nam, H Y [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    Temperature distribution measurements in the mockup apparatus of reactor vessel were performed to determine the effective thermal conductivity of porous media with different geometry and to obtain the experimental data for the heat transfer processes by natural convection occurring in the air duct. The temperature distributions at four separated sections with different arrangements of porous media have different slopes according to the geometrical configuration. From the measured temperature distribution, effective thermal conductivity have been derived using the least square fitting method. The test at air duct was performed to the high heat removal at 3.4kW/m{sup 2} by the natural convection from the outer wall to the air. And also the temperature distributions in the sir duct agree well with the 1/7th power-law turbulent temperature distribution. The obtained heat transfer data have been compared with the Shin`s and Sieger`s correlations. 10 refs., 6 figs. (Author)

  18. Condenser design optimization and operation characteristics of a novel miniature loop heat pipe

    International Nuclear Information System (INIS)

    Wan Zhenping; Wang Xiaowu; Tang Yong

    2012-01-01

    Highlights: ► A novel miniature LHP (mLHP) system was presented. ► Optimal design of condenser was considered. ► The heat transfer performance was investigated experimentally. - Abstract: Loop heat pipe (LHP) is a promising means for electronics cooling since LHP is a exceptionally efficient heat transfer device. In this paper, a novel miniature LHP (mLHP) system is presented and optimal design of condenser is considered seeing that evaporators have been able to handle very high-heat fluxes with low-heat transfer resistances since most of the previous researchers focused on the evaporator of mLHP. The arrayed pins were designed and machined out on the bottom of condenser to enhance condensation heat transfer. The parameters of the arrayed pins, including layout, cross-section shape and area, were optimized by finite element analysis. Tests were carried out on the mLHP with a CPU thermal simulator using forced air convection condenser cooling to validate the optimization. The operation characteristics of the mLHP with optimal design parameters of condenser were investigated experimentally. The experimental results show that the mLHP can reject head load 200 W while maintaining the cooled object temperatures below 100 °C, and for a variable power applied to the evaporator, the system presents reliable startups and continuous operation.

  19. An experimental study of heat transfer characteristics of single and two-phase flows in an annular tube with external vibrations

    International Nuclear Information System (INIS)

    Zaki, Adel M.; Abou El-Kassem, S.K.; Abdalla Hanafi

    2003-01-01

    An experimental study of the external vibration effect on the heat transfer characteristics of single and two-phase flows in an annular tube is carried out. An experimental set-up was constructed to study the heat transfer in a stationary, as well as, in oscillating annular tube. The annular tube was heated electrically through the inner surface, which is a stainless steel tube (St 304) 13 mm outer diameter, while the outer tube, of 3.7 cm inner diameter, made from a glass. The experimental set-up was equipped with a vibrating system to excite the annular tube in the frequency range of 0 up to 134 Hz. Several sensors for measuring wall and fluid temperatures, heat fluxes and volume flow rates of both phases were used. The obtained results show that the heat transfer coefficient can be significantly increased by vibration of the test section. (author)

  20. Effects of Heat Input on Microstructure, Corrosion and Mechanical Characteristics of Welded Austenitic and Duplex Stainless Steels: A Review

    Directory of Open Access Journals (Sweden)

    Ghusoon Ridha Mohammed

    2017-01-01

    Full Text Available The effects of input heat of different welding processes on the microstructure, corrosion, and mechanical characteristics of welded duplex stainless steel (DSS are reviewed. Austenitic stainless steel (ASS is welded using low-heat inputs. However, owing to differences in the physical metallurgy between ASS and DSS, low-heat inputs should be avoided for DSS. This review highlights the differences in solidification mode and transformation characteristics between ASS and DSS with regard to the heat input in welding processes. Specifically, many studies about the effects of heat energy input in welding process on the pitting corrosion, intergranular stress, stresscorrosion cracking, and mechanical properties of weldments of DSS are reviewed.

  1. Effects of heating energy and heating position on the conversion characteristics of the catalyst of a four-stroke motorcycle engine in cold start conditions

    International Nuclear Information System (INIS)

    Horng, R.-F.; Chou, H.-M.; Hsu, T.-C.

    2004-01-01

    The effects of heating energy and heating position on the conversion efficiency of an electrically heated catalyst of a four stroke motorcycle engine under cold start conditions were investigated in this study. In general, during cold start, the operating temperatures of a four stroke motorcycle engine and its catalyst would not be optimized. It was found in this paper that by applying heat to the catalyst however, the reaction of the catalyst could be promoted, which, consequently, improved the conversion efficiency. The experimented parameters were heating energy, heating position, heating temperature and the carbon monoxide (CO) setting level. The heating temperatures included 100, 140 and 180 deg. C, while three different heating powers and six different heating positions were used. The CO levels were set as 1.0%, 1.8% and 2.3%. The best CO conversion efficiency was obtained by applying heating at the inlet of the catalyst. It was revealed that a high heating power induced a high temperature rising rate and, consequently, a high CO conversion efficiency. In terms of energy economy efficiency, however, heating at the mid-section of the catalyst gave the best results and through a relatively low heating power

  2. Comparative genome analysis of a thermotolerant Escherichia coli obtained by Genome Replication Engineering Assisted Continuous Evolution (GREACE) and its parent strain provides new understanding of microbial heat tolerance.

    Science.gov (United States)

    Luan, Guodong; Bao, Guanhui; Lin, Zhao; Li, Yang; Chen, Zugen; Li, Yin; Cai, Zhen

    2015-12-25

    Heat tolerance of microbes is of great importance for efficient biorefinery and bioconversion. However, engineering and understanding of microbial heat tolerance are difficult and insufficient because it is a complex physiological trait which probably correlates with all gene functions, genetic regulations, and cellular metabolisms and activities. In this work, a novel strain engineering approach named Genome Replication Engineering Assisted Continuous Evolution (GREACE) was employed to improve the heat tolerance of Escherichia coli. When the E. coli strain carrying a mutator was cultivated under gradually increasing temperature, genome-wide mutations were continuously generated during genome replication and the mutated strains with improved thermotolerance were autonomously selected. A thermotolerant strain HR50 capable of growing at 50°C on LB agar plate was obtained within two months, demonstrating the efficiency of GREACE in improving such a complex physiological trait. To understand the improved heat tolerance, genomes of HR50 and its wildtype strain DH5α were sequenced. Evenly distributed 361 mutations covering all mutation types were found in HR50. Closed material transportations, loose genome conformation, and possibly altered cell wall structure and transcription pattern were the main differences of HR50 compared with DH5α, which were speculated to be responsible for the improved heat tolerance. This work not only expanding our understanding of microbial heat tolerance, but also emphasizing that the in vivo continuous genome mutagenesis method, GREACE, is efficient in improving microbial complex physiological trait. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Basketball lay-up - foot loading characteristics and the number of trials necessary to obtain stable plantar pressure variables.

    Science.gov (United States)

    Chua, YaoHui K; Quek, Raymond K K; Kong, Pui W

    2017-03-01

    This study aimed (1) to profile the plantar loading characteristics when performing the basketball lay-up in a realistic setting and (2) to determine the number of trials necessary to establish a stable mean for plantar loading variables during the lay-up. Thirteen university male basketball players [age: 23.0 (1.4) years, height: 1.75 (0.05) m, mass: 68.4 (8.6) kg] performed ten successful basketball lay-ups from a stationary position. Plantar loading variables were recorded using the Novel Pedar-X in-shoe system. Loading variables including peak force, peak pressure, and pressure-time integral were extracted from eight foot regions. Performance stability of plantar loading variables during the take-off and landing steps were assessed using the sequential averaging technique and intra-class correlation coefficient (ICC). High plantar loadings were experienced at the heel during the take-off steps, and both the heel and forefoot regions upon landing. The sequential estimation technique revealed a five-eight trial range to achieve a stable mean across all plantar loading variables, whereas ICC analysis was insensitive to inter-trial differences of repeated lay-up performances. Future studies and performance evaluation protocols on plantar loading during basketball lay-ups should include at least eight trials to ensure that the measurements obtained are sufficiently stable.

  4. Phase change and heat transfer characteristics of a eutectic mixture of palmitic and stearic acids as PCM in a latent heat storage system

    International Nuclear Information System (INIS)

    Baran, Guelseren; Sari, Ahmet

    2003-01-01

    The phase change and heat transfer characteristics of a eutectic mixture of palmitic and stearic acids as phase change material (PCM) during the melting and solidification processes were determined experimentally in a vertical two concentric pipes energy storage system. This study deals with three important subjects. First is determination of the eutectic composition ratio of the palmitic acid (PA) and stearic acid (SA) binary system and measurement of its thermophysical properties by differential scanning calorimetry (DSC). Second is establishment of the phase transition characteristics of the mixture, such as the total melting and solidification temperatures and times, the heat transfer modes in the melted and solidified PCM and the effect of Reynolds and Stefan numbers as initial heat transfer fluid (HTF) conditions on the phase transition behaviors. Third is calculation of the heat transfer coefficients between the outside wall of the HTF pipe and the PCM, the heat recovery rates and heat fractions during the phase change processes of the mixture and also discussion of the effect of the inlet HTF parameters on these characteristics. The DSC results showed that the PA-SA binary system in the mixture ratio of 64.2:35.8 wt% forms a eutectic, which melts at 52.3 deg. C and has a latent heat of 181.7 J g -1 , and thus, these properties make it a suitable PCM for passive solar space heating and domestic water heating applications with respect to climate conditions. The experimental results also indicated that the eutectic mixture of PA-SA encapsulated in the annulus of concentric double pipes has good phase change and heat transfer characteristics during the melting and solidification processes, and it is an attractive candidate as a potential PCM for heat storage in latent heat thermal energy storage systems

  5. Characteristics of ion Bernstein wave heating in JIPPT-II-U tokamak

    International Nuclear Information System (INIS)

    Okamoto, M.; Ono, M.

    1985-11-01

    Using a transport code combined with an ion Bernstein wave tokamak ray tracing code, a modelling code for the ion Bernstein wave heating has been developed. Using this code, the ion Bernstein wave heating experiment on the JIPPT-II-U tokamak has been analyzed. It is assumed that the resonance layer is formed by the third harmonic of deuterium-like ions, such as fully ionized carbon, and oxygen ions near the plasma center. For wave absorption mechanisms, electron Landau damping, ion cyclotron harmonic damping, and collisional damping are considered. The characteristics of the ion Bernstein wave heating experiment, such as the ion temperature increase, the strong dependence of the quality factor on the magnetic field strength, and the dependence of the ion temperature increment on the input power, are well reproduced

  6. Heat Transfer Characteristics on the Squealer Tip of gas turbine blade in a linear cascade

    International Nuclear Information System (INIS)

    Lee, Woo Jin; Lee, Dong Hyun; Kim, Kyung Min; Cho, Hyung Hee; Lee, Dong Ho; Kang, Shin Hyoung

    2007-01-01

    The present study investigates local heat/mass transfer characteristics on blade tip surfaces with squealer rim in a linear cascade. A cascade experiment setup consists of three airfoils. The airfoil has variable tip clearance(1, 2, 3% of axial chord length) and rim height(3, 6, 9% of axial chord length). Main flow Reynolds number based on axial chord is 1.5 x 10 5 . The axial chord length and turning angle is 237mm and 126 .deg. respectively. Naphthalene sublimation method is used to measure detailed mass transfer coefficient on the blade. The results show that as the tip clearance increases, high heat transfer region moves from upstream to downstream. Also, as the rim height increases, high heat transfer region tends to move toward the suction side

  7. Heat characteristic analysis of a conduction cooling toroidal-type SMES magnet

    International Nuclear Information System (INIS)

    Kim, K.M.; Kim, A.R.; Kim, J.G.; Kim, D.W.; Park, M.; Yu, I.K.; Eom, B.Y.; Sim, K.; Kim, S.H.; Shon, M.H.; Kim, H.J.; Bae, H.J.; Seong, K.C.

    2010-01-01

    This paper analyzed the heat characteristics of a conduction cooling toroidal-type SMES magnet. The authors designed and manufactured a conduction cooling toroidal-type SMES magnet which consists of 30 double pancake coils. One (a single pancake coil) of a double pancake coil is arranged at an angle of 6 o from each other. The shape of the toroidal-type SMES magnet was designed by a 3D CAD program. The heat invasion was investigated under no-load condition and the thermal characteristic of the toroidal-type SMES magnet was analyzed using the Finite Elements Method program. Both the analyzed and the experiment results are compared and discussed in detail.

  8. Drying kinetics and characteristics of dried gambir leaves using solar heating and silica gel dessicant

    Science.gov (United States)

    Hasibuan, R.; Hidayati, J.; Sundari, R.; Wicaksono, A. S.

    2018-02-01

    A drying combination of solar heating and silica gel dessicant has been applied to dry gambir leaves. The solar energy is captured by a collector to heat the air and the hot air is used to dry gambir leaves in a drying chamber. An exhaust fan in drying chamber assists to draw water molecules from gambir leaves accelerated by silica gel dessicant. This study has investigated the drying kinetics and drying characteristics of gambir leaves drying. In drying operation the air velocity is tuned by a PWM (pulse width modulation) controller to adjust minimum and maximum level, which is based on the rotation speed of the exhaust fan. The results show that the air velocity influenced the drying kinetics and drying characteristics of gambir leaves using solar-dessicant drying at 40 cm distance between exhaust fan and silica gel dessicant.

  9. EXPERIMENTAL INVESTIGATION OF HEAT STORAGE CHARACTERISTIC OF UREA AND BORAX SALT GRADIENT SOLAR PONDS

    Directory of Open Access Journals (Sweden)

    Hüseyin KURT

    2006-03-01

    Full Text Available Salt gradient solar ponds are simple and low cost solar energy system for collecting and storing solar energy. In this study, heat storage characteristic of urea and borax solutions in the solar pond were examined experimentally. Establishing density gradients in different concentration, variations in the temperature and density profiles were observed in four different experiments. Maximum storage temperatures were measured as 28ºC and 36 ºC for the ponds with urea and borax solution, respectively. The temperature difference between the bottom and the surface of the pond were measured as 13 ºC for urea and 17 ºC for borax- solutions. According to these results, heat storage characteristic of the solar pond with borax solution was found to be better than urea solution.

  10. The obtaining of statistical characteristics of informative features of signals in the Autonomous information systems using neural networks

    Directory of Open Access Journals (Sweden)

    V. K. Hohlov

    2014-01-01

    Full Text Available The article studies a neural network approach to obtain the statistical characteristics of the input vector implementations of signal and noise at ill-conditioned matrices of correlation moments to solve the problems to select and reduce the vector dimensions of informative features at detection and recognition of signals and noise based on regression methods.A scientific novelty is determined by applying neural network algorithms for the efficient solution of problems to select the informative features and determine the parameters of regression algorithms in terms of the degeneracy or ill-conditioned data with unknown expectation and covariance matrices.The article proposes to use a single-layer neural network with no zero weights and activation functions to calculate the initial regression characteristics and the mean-square value error of multiple initial regression representations, which are necessary to justify the selection of informative features, reduce a dimension of sign vectors and implement the regression algorithms. It is shown that when excluding direct links between the inputs and their corresponding neurons, in the training network the weight coefficients of neuron inputs are the coefficients of initial multiple regression, the error meansquare value of multiple initial regression representations is calculated at the outputs of neurons. The article considers conditionality of the problem to calculate the matrix that is inverse one for matrix of correlation moments. It defines a condition number, which characterizes the relative error of stated task.The problem concerning the matrix condition of the correlation moment of informative signal features and noise arises when solving the problem to find the multiple coefficients of initial regression (MCIR and the residual mean-square values of the multiple regression representations. For obtaining the MCIR and finding the residual mean-square values the matrix of correlation moments of

  11. Numerical analysis and experimental validation of heat transfer characteristic for flat-plate solar air collector

    International Nuclear Information System (INIS)

    Hung, Tzu-Chen; Huang, Tsung-Jie; Lee, Duen-Sheng; Lin, Chih-Hung; Pei, Bau-Shei; Li, Zeng-Yao

    2017-01-01

    Highlights: • Various types of solar air collectors are discussed. • CFD has been used to validate the characteristics of heat transfer. • Solar Ray Tracing has been successfully used for thermal radiation flux. - Abstract: This study combines both concepts of solar ventilation technology and solar air collector. This is a quite innovative and potential facility to effectively use thermal energy and reduce the accumulation of heat in the indoor space simultaneously. The purpose of this study is to create a prototype and implement the experiments. Computational fluid dynamics (CFD) approach is employed to validate the characteristics of the flow and heat transfer. For the accuracy of numerical predictions, the method of Solar Ray Tracing was used for thermal radiation flux as boundary condition on the wall. The local heat transfer correlation was investigated to predict surrounding wind speed upon device cover. Three sorts of glasses and several aspect ratios of flow channels have been compared to conclude the optimal configuration. In addition, four important factors, such as the stagnant layer thickness, emissivity on the illustrated surface, mass flow rate and the height of the device, are also considered and discussed in detail. The result showed that the optimal design is dominated by the combination of an aspect ratio of 50 mm:10 mm, and appropriate mass flow rate to the height of the device. The present work on thermal energy collection can assist us in designing a powerful solar air collector in some potential applications.

  12. Characteristics of a random force in the phenomenological description of surface oscillations of heated spherical nuclei

    International Nuclear Information System (INIS)

    Svin'in, I.R.

    1987-01-01

    A method of calculation of statistical characteristics of a random force is presented. This method is used in the description of oscillations of heated spherical nuclei in the Brownian movement approximation. The mean value and the spectral density of the correlation function are calculated in the noninteracting-particle model. The dependence of the spectral density on the number of nucleons and on the temperature of the nucleus is analyzed

  13. Effect of microwave irradiation on selective heating behavior and magnetic separation characteristics of Panzhihua ilmenite

    International Nuclear Information System (INIS)

    Zhao, Wei; Chen, Jin; Chang, Xiaodong; Guo, Shenghui; Srinivasakannan, C.; Chen, Guo; Peng, Jinhui

    2014-01-01

    Highlights: • Microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite. • The mineral processing properties of microwave treated ilmenite were generally as good as or better than that of initial ilmenite. • The microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. - Abstract: The influences of microwave irradiation on the surface characteristics of Panzhihua ilmenite were systematically investigated. The crystal structures, surface morphology and surface chemical functional groups of ilmenite were characterized before and after microwave irradiation and magnetic separation for different microwave treatment times by using various methods, such as XRD, SEM, and FT-IR, respectively. XRD analysis showed that the microwave treated ilmenite has the strongest peaks of phase more than that of raw samples, indicates that the crystalline compound of ilmenite increased with the microwave irradiation time. SEM analysis showed the micro-cracking appeared at many grain boundaries of ilmenite after being pretreated by microwave treatment. The separations of ilmenite from gangue minerals were completed and the micro-fissure within ilmenite minerals were also formed, which could be attributed to the microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. The mineral processing results showed that the magnetic separation characteristics and properties of microwave treated ilmenite samples were better than that of microwave untreated ilmenite samples. It was concluded that microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite

  14. Heat transfer, erosion and acid condensation characteristics for novel H-type finned oval tube

    International Nuclear Information System (INIS)

    Wang, Y; Zhao, X; Tang, G

    2015-01-01

    Low efficiency of heat transfer, acid corrosion and erosion of economizers affect the economy and security in coal-fired power plants significantly. The H-type finned oval tube is proposed to alleviate these problems. Based on the H-type finned oval tube, we investigated three novel types of fins, including bleeding dimples, longitudinal vortex generators (LVGs), and compound dimple-LVG. We considered the three aspects together, and obtained the heat transfer, acid condensation rate and erosion loss. The results show that the tube bank with the new structured fins can improve the performance on the three aspects, and the compound dimple-LVG performs the highest comprehensive effect. (paper)

  15. Effect of polyvinylpyrrolidone on cerium oxide nanoparticle characteristics prepared by a facile heat treatment technique

    Directory of Open Access Journals (Sweden)

    Anwar Ali Baqer

    Full Text Available An aqueous medium composed of polyvinylpyrrolidone (PVP and cerium nitrates at calcination temperature was utilised in the production of cerium oxide (CeO2 semiconductor nanoparticles. A variety of analytical approaches was utilized to examine the structural, morphological and optical characteristics of the resulting nanoparticles. Differential thermal (DTA and thermogravimetric (TGA analyses, indicated that the best calcination temperatures for achieving CeO2 nanoparticle production were more than 485 °C. The results from Fourier-transform infrared (FTIR verified the formation of a crystalline structure after calcination procedures were performed to remove residual organic compounds. Additionally, results from X-ray diffraction (XRD analysis confirmed the cubic fluorite structure of the CeO2 produced. Samples were also analysed by energy dispersive spectroscopy (EDXA which indicated the existence of O and Ce in the samples. Field emission scanning electron microscopy (FESEM was used in the characterisation of nanoparticle morphological features. Transmission electron microscopy (TEM was employed to estimate typical nanoparticle and distribution within sample. This analysis indicated that mean particle sizes were inversely correlated with PVP concentration, with nanoparticle sizes ranging between 12 ± 7 nm at 0.03 g/mL PVP and 6 ± 2 nm at 0.05 g/mL PVP. These results corroborated those obtained by XRD analysis. A UV–vis spectrophotometer was utilised in the demonstration of optical properties and to examine the band gap energy of samples. The potential UV-shielding properties of the nanoparticles were demonstrated by the observed blue shift of the estimated optical energy band, i.e. from 3.35 to 3.43 eV, whilst PL spectra results indicated that decreasing particle size was associated with diminishing photoluminescence intensity. Keywords: Cerium oxide nanoparticles, Heat treatment technique, Structural properties, Optical

  16. Experimental study of heat transfer and pressure drop characteristics of air/water and air-steam/water heat exchange in a polymer compact heat exchanger

    NARCIS (Netherlands)

    Cheng, L.; Geld, van der C.W.M.

    2005-01-01

    Experiments of heat transfer and pressure drop in a polymer compact heat exchanger made of PolyVinyliDene-Fluoride were conducted under various conditions for air/water heat exchange and air-steam/water heat exchange, respectively. The overall heat transfer coefficients of air-steam/water heat

  17. Influence of heat treatment on physicochemical and rheological characteristics of natural yogurts

    Directory of Open Access Journals (Sweden)

    Juliana Aparecida Célia

    2017-08-01

    Full Text Available The aim of this study was to assess the influence of heat treatment on physicochemical and rheological characteristics of natural yogurts, as well as the influence of lyophilization process on natural yogurts after reconstitution. In the first experiment, three yogurt treatments were processed, as follows: Treatment 1, yogurt produced with raw refrigerated milk; Treatment 2, yogurt produced with refrigerated pasteurized milk; and Treatment 3, yogurt produced with UHT (ultra-high temperature milk, in addition to analyses of fat, protein, moisture, titratable acidity, and pH. The shelf life of yogurts at 1, 8, 15, 22, and 29 days of storage, as well as pH, acidity, syneresis, viscosity, viable lactic bacteria, and total coliforms were also assessed. In the second experiment, yogurts were submitted to lyophilization process, performed by scanning electron microscopy analysis and subsequently in those reconstituted, in addition to being assessed the physicochemical, rheological, and viable lactic bacteria characteristics. The results found in the first experiment showed that heat treatment was positive for viscosity, syneresis, and lactic bacteria, being viable until the 15th day of storage only for yogurts submitted to heat treatment. In the second experiment, lyophilization preserved the physicochemical characteristics of yogurts, but the number of initial lactic bacteria was different, also negatively affecting yogurt viscosity.

  18. On the characteristics and application of thin wall welded titanium tubes for heat transfer

    International Nuclear Information System (INIS)

    Nishimura, Takashi; Miyamoto, Yoshiyuki

    1985-01-01

    Because of the excellent corrosion resistance, thin wall welded titanium tubes have become to be used in large number as the heat transfer tubes of condensers and seawater desalting plants using seawater in place of conventional copper alloy tubes. Especially in nuclear power plants, the all titanium condensers using thin wall welded titanium tubes and titanium tube plates were adopted in the almost all plants under construction or expected to be constructed. In this report, the various characteristics of thin wall welded titanium tubes required for using them as heat transfer tubes, such as corrosion resistance, heat transfer characteristics, fatigue strength and expanding characteristics, are outlined, and the state of use is described. At first, relatively thick seamless titanium tubes were used for chemical industry, but thereafter, due to the advance of the mass production techniques, the welded titanium tubes of less than 0.7 mm thickness and high quality have become to be supplied at low cost. In 1969, titanium tubes were used for the first time in Japan for the air cooler in the condenser of Akita Power Station, Tohoku Electric Power Co., Inc. The features of titanium are small specific gravity, small linear expansion coefficient and small Young's modulus. (Kako, I.)

  19. Experimental Investigation of Heat Transfer Characteristics of Automobile Radiator using TiO2-Nanofluid Coolant

    Science.gov (United States)

    Salamon, V.; Senthil kumar, D.; Thirumalini, S.

    2017-08-01

    The use of nanoparticle dispersed coolants in automobile radiators improves the heat transfer rate and facilitates overall reduction in size of the radiators. In this study, the heat transfer characteristics of water/propylene glycol based TiO2 nanofluid was analyzed experimentally and compared with pure water and water/propylene glycol mixture. Two different concentrations of nanofluids were prepared by adding 0.1 vol. % and 0.3 vol. % of TiO2 nanoparticles into water/propylene glycol mixture (70:30). The experiments were conducted by varying the coolant flow rate between 3 to 6 lit/min for various coolant temperatures (50°C, 60°C, 70°C, and 80°C) to understand the effect of coolant flow rate on heat transfer. The results showed that the Nusselt number of the nanofluid coolant increases with increase in flow rate. At low inlet coolant temperature the water/propylene glycol mixture showed higher heat transfer rate when compared with nanofluid coolant. However at higher operating temperature and higher coolant flow rate, 0.3 vol. % of TiO2 nanofluid enhances the heat transfer rate by 8.5% when compared to base fluids.

  20. Effect of Heating Rate on Pyrolysis Behavior and Kinetic Characteristics of Siderite

    Directory of Open Access Journals (Sweden)

    Xiaolong Zhang

    2017-11-01

    Full Text Available The pyrolysis characteristics of siderite at different heating rates under the neutral atmosphere were investigated using various tools, including comprehensive thermal analyzer, tube furnace, X-ray diffraction (XRD, scanning electron microscope (SEM, energy-dispersive spectrometry (EDS and vibrating specimen magnetometer (VSM measurements. The reaction of siderite pyrolysis followed the one-step reaction under the neutral atmosphere: FeCO3 → Fe3O4 + CO2 + CO. As the increasing of heating rate, the start and end pyrolysis temperatures and temperate where maximum weight loss rate occurred increased, while the total mass loss were essentially the same. Increasing heating rate within a certain range was in favor of shortening the time of each reaction stage, and the maximum conversion rate could be reached with a short time. The most probable mechanism function for non-isothermal pyrolysis of siderite at different heating rates was A1/2 reaction model (nucleation and growth reaction. With increasing heating rate, the corresponding activation energies and the pre-exponential factors increased, from 446.13 to 505.19 kJ∙mol−1, and from 6.67 × 10−18 to 2.40 × 10−21, respectively. All siderite was transformed into magnetite with a porous structure after pyrolysis, and some micro-cracks were formed into the particles. The magnetization intensity and specific susceptibility increased significantly, which created favorable conditions for the further effective concentration of iron ore.

  1. Effects of stabilizers on the heat transfer characteristics of a nuclear waste canister

    International Nuclear Information System (INIS)

    Vafai, K.; Ettefagh, J.

    1986-07-01

    This report summarizes the feasibility and the effectiveness of using stabilizers (internal metal structural components) to augment the heat transfer characteristics of a nuclear waste canister. The problem was modeled as a transient two-dimensional heat transfer in two physical domains - the stabilizer and the wedge (a 30-degree-angle canister segment), which includes the heat-producing spent-fuel rods. This problem is solved by a simultaneous and interrelated numerical investigation of the two domains in cartesian and polar coordinate systems. The numerical investigations were performed for three cases. In the first case, conduction was assumed to be the dominant mechanism for heat transfer. The second case assumed that radiation was the dominant mechanism, and in the third case both radiation and conduction were considered as mechanisms of heat transfer. The results show that for typical conditions in a waste package design, the stabilizers are quite effective in reducing the overall temperature in a waste canister. Furthermore, the results show that increasing the stabilizer thickness over the thickness specified in the present design has a negligible effect on the temperature distribution in the canister. Finally, the presence of the stabilizers was found to shift the location of the peak temperature areas in the waste canister

  2. Distribution characteristics of terrestrial heat flow density in Jiyang depression of Shengli Oilfield, East China

    Institute of Scientific and Technical Information of China (English)

    GONG; Yuling; WANG; Liangshu; LIU; Shaowen; LI; Cheng; HAN

    2004-01-01

    Based on the geo-temperature data of 13 systematically continuous temperature log curves and 700 testing oil boreholes in Jiyang depression, Shengli Oilfield, and the measured thermal conductivities of 47 rock samples, the terrestrial heat flow densities of 114 boreholes of Jiyang depression and its surrounding areas are determined, including 13 of those data derived from systemically continuous temperature logging. The results show that Jiyang depression has a relatively high background heat flow with an average value (65.8 ± 5.4) mW/m2. The lateral variation of heat flow in basin has negative correlation with basement depth. Moreover, heat flow of uplift areas with shallower basement is high, so are those of regions with volcanic rocks, and those of depression areas with deep basement are relatively low. The heat flow densities of different structural units of Jiyang depression can be summarized as follows: The average heat flow value of Zhanhua sag is (67.4 ± 5.3) mW/m2, higher than that of the whole basin, that of Dongying sag is (66.0 ± 6.1) mW/m2, and that of Chezhen sag is (65.1 ± 3.7) mW/m2. It is apparent that these latter two values are approximate to the average value of the whole Jiyang depression,while the average value of Huimin sag is (63.6±5.0) mW/m2, lower than that of the whole basin. In fact, the basement depth and the distribution framework of uplift and depression areas are all controlled by the process of lithosphere extension. In addition, the distribution of volcanic rocks in basin is also relatively close to this extension geodynamic process. In summary, the distribution characteristics of terrestrial heat flow of Jiyang depression is determined by the Cenozoic tectono-thermal events of this region.

  3. The Characteristics of natural convection heat transfer of Al_2O_3–water nano fluid flow in a vertical annulus pipe

    International Nuclear Information System (INIS)

    Reinaldy Nazar

    2016-01-01

    Results of several researches have shown that nano fluids have better thermal characteristics than conventional fluid (water). In this regard, ideas for using nano fluids as an alternative heat transfer fluid in the reactor coolant system have been well developed. Meanwhile the natural convection in a vertical annulus pipe is one of the important mechanisms of heat transfer and is found at the TRIGA research reactor, the new generation nuclear power plants and other energy conversion devices. On the other hand, the heat transfer characteristics of nano fluids in a vertical annulus pipe has not been known. Therefore, it is important to do research continuously to analyze the heat transfer nano fluids in a vertical annulus pipe. This study has carried out numerical analysis by using computer code of CFD (computational of fluids dynamic) on natural convection heat transfer characteristics of nano fluids flow of Al_2O_3-water 2 % volume in the vertical annulus pipe. The results showed an increase in heat transfer performance (Nusselt numbers - NU) by 20.5 % - 35 %. In natural convection mode with Rayleigh numbers 2.471 e"+"0"9 ≤ Ra ≤ 1.955 e"+"1"3 obtained empirical correlations for water is N_U = 1.065 (R_a(D_H/x))"0"."1"7"9 and empirical correlations for Al_2O_3-water nano fluids is N_U = 14.869 (R_a(D_H/x))"0"."1"1"5.(author)

  4. First In-Core Simultaneous Measurements of Nuclear Heating and Thermal Neutron Flux Obtained With the Innovative Mobile Calorimeter CALMOS Inside the OSIRIS Reactor

    Science.gov (United States)

    Carcreff, Hubert; Salmon, Laurent; Bubendorff, Jacques; Lepeltier, Valérie

    2016-10-01

    Nuclear heating inside a MTR reactor has to be known in order to design and run irradiation experiments which have to fulfill target temperature constraints. This measurement is usually carried out by calorimetry. The innovative calorimetric system, CALMOS, has been studied and built in 2011 for the 70MWth OSIRIS reactor operated by CEA. Thanks to a new type of calorimetric probe, associated to a specific displacement system, it provides measurements along the fissile height and above the core. Calorimeter working modes, measurement procedures, main modeling and experimental results and expected advantages of this new technique have been already presented in previous papers. However, these first in-core measurements were not performed beyond 6 W · g-1, due to an inside temperature limitation imposed by a safety authority requirement. In this paper, we present the first in-core simultaneous measurements of nuclear heating and conventional thermal neutron flux obtained by the CALMOS device at 70 MW nominal reactor power. For the first time, this experimental system was operated in nominal in-core conditions, with nominal neutron flux up to 2.7 1014 n · cm-2 · s-1 and nuclear heating up to 12 W · g-1. After a brief reminder of the calorimetric cell configuration and displacement system specificities, first nuclear heating distributions at nominal power are presented and discussed. In order to reinforce the heating evaluation, a comparison is made between results obtained by the probe calibration coefficient and the zero methods. Thermal neutron flux evaluation from SPND signal processing required a specific TRIPOLI-4 Monte Carlo calculation which has been performed with the precise CALMOS cell geometry. In addition, the Finite Element model for temperatures map prediction inside the calorimetric cell has been upgraded with recent experimental data obtained up to 12 W · g-1. Finally, the experience feedback led us to improvement perspectives. A second device is

  5. The Calculated and Measured Performance Characteristics of a Heated-Wire Liquid-Water-Content Meter for Measuring Icing Severity

    Science.gov (United States)

    Neel, Carr B.; Steinmetz, Charles P.

    1952-01-01

    Ground tests have been made of an instrument which, when assembled in a more compact form for flight installation, could be used to obtain statistical flight data on the liquid-water content of icing clouds and to provide an indication of icing severity. The sensing element of the instrument consists of an electrically heated wire which is mounted in the air stream. The degree of cooling of the wire resulting from evaporation of the impinging water droplets is a measure. of the liquid-water content of the cloud. Determination of the value of the liquid-water content from the wire temperature at any instant requires a knowledge of the airspeed, altitude, and air temperature. An analysis was made of the temperature response of a heated wire exposed to an air stream containing water drops. Comparisons were made of the liquid-water content as measured with several heated wires and absorbent cylinders in an artificially produced cloud. For one of the wires, comparative tests were made with a rotating-disk icing-rate meter in an icing wind tunnel. From the test results, it was shown that an instrument for measuring the concentration of liquid water in an air stream can be built using an electrically heated wire of known temperatureresistance characteristics, and that the performance of such a device can be predicted using appropriate theory. Although an instrument in a form suitable for gathering statistical data in flight was not built, the practicability of constructing such an instrument was illustrated. The ground-test results indicated that a flight heated-wire instrument would be simple and durable, would respond rapidly to variations in liquid-water content, and could be used for the measurement of water content in clouds which are above freezing temperature, as well as in icing clouds.

  6. Cooling characteristics of light and heat composite panel; Hikari{center_dot}netsu fukugo paneru no rekyakutokusei

    Energy Technology Data Exchange (ETDEWEB)

    Machida, Satoshi [Science University of Tokyo, Tokyo (Japan)

    1999-07-31

    The Japan Solar Energy Soc. encouraging prize is really thank you this time receiving. Present winning prize is regarded as becoming large self-confidence and further encouragement in advancing the research in future. Duplicates and resources energy depletion problem and environmental problem, etc. will become serious more and more in respect of the twenty-first century just before. It is the threat even in the inside on the increase of the electric power demand by the popularization of air conditioner, etc., and peak shaving of the electric power, etc. must be urgently carried out. We heavily carry out the research of catching, width shot heating and cooling panel constituted by the thermo device module and light and heat composite panel which combined photovoltaic power generation panel in respect of this problem. The development of this panel was solved with the purpose this time, we produce the test equipment experimentally in outdoors, and the data was acquired. As the result, though it is possible to obtain the case in which it operated as air-cooling this panel, and temperature gradient of largest 6 degrees C, and it is the analysis, and it 4s, when it was used in July, It was possible to obtain 4.2 degrees C mean temperature difference. It is the place which has installed improved light and heat composite panel in which we suggested afterwards trial and error at present in the roof. And, it will become also reporting schedule on heating characteristics of this panel in future. Though it consists finally, everybody of Komatsu central laboratory, who received support, when this study was carried out, is asked for the slender face, the attention of thanks is shown. (translated by NEDO)

  7. Influence of radiative heat and mass transfer mechanism in system “water droplet-high-temperature gases” on integral characteristics of liquid evaporation

    Directory of Open Access Journals (Sweden)

    Glushkov Dmitrii O.

    2015-01-01

    Full Text Available Physical and mathematical (system of differential equations in private derivatives models of heat and mass transfer were developed to investigate the evaporation processes of water droplets and emulsions on its base moving in high-temperature (more than 1000 K gas flow. The model takes into account a conductive and radiative heat transfer in water droplet and also a convective, conductive and radiative heat exchange with high-temperature gas area. Water vapors characteristic temperature and concentration in small wall-adjacent area and trace of the droplet, numerical values of evaporation velocities at different surface temperature, the characteristic time of complete droplet evaporation were determined. Experiments for confidence estimation of calculated integral characteristics of processes under investigation - mass liquid evaporation velocities were conducted with use of cross-correlation recording video equipment. Their satisfactory fit (deviations of experimental and theoretical velocities were less than 15% was obtained. The influence of radiative heat and mass transfer mechanism on characteristics of endothermal phase transformations in a wide temperature variation range was established by comparison of obtained results of numerical simulation with known theoretical data for “diffusion” mechanisms of water droplets and other liquids evaporation in gas.

  8. Serpentine tube heat transfer characteristic under accident condition in gas cooled reactors

    International Nuclear Information System (INIS)

    Abouhadra, D.S.; Byrne, J.E.

    2004-01-01

    In nuclear reactors of the Magnox or advanced gas Cooled type, serpentine tubing is used in some designs to generate steam in a once through arrangement. The calculation of accident conditions using two phase flow codes requires knowledge of the heat transfer behavior of the boiler steam side. A series of experiments to study the blowdown characteristics of a typical serpentine boiler section was devised in order to validate the MARTHA section of the MACE code used by nuclear Electric. The tests were carried out on the Thermal Hydraulics Experimental Research Assembly (THERA) loop at Manchester University. The Thermal Hydraulic Experimental Research Assembly was designed to operate with pressures up to 180 bar and temperatures of 450degC. The geometry and dimensions of this test section were similar to part of a gas cooled reactor boiler of the Hinkley Point design. Blowdown from a pressure of 60 bar with subcoolings of 5degC, 50degC, 100degC formed the main part of the programme. A set of tests was conducted using discharge orifices of different sizes to produce depressurization times from 30 s to 10 mins, and in a few cases, the duration of blowdown approached 1 hour. These times were defined using the criterion of blowdown end as a final pressure of 10% of the initial pressure. Pressures, wall and fluid temperatures were all measured at average time intervals of 1.1s during the excursion and an inventory of the remaining water content in the serpentine was taken when the blowdown ended. Some tests were also conducted at an initial pressure of 30 bar. The results obtained show interesting stratification effects for the relatively fast discharge, with substantial wall circumferential temperature variations. For these tests, a relatively small water inventory remained after blowdown. The discharge characteristics of the serpentine in terms of orifice size have been mapped, and tests at 30 bar show the equivalence in terms of orifice size have been mapped

  9. Comparison of tubeside condensation and evaporation characteristics of smooth and enhanced heat transfer 1EHT tubes

    International Nuclear Information System (INIS)

    Kukulka, David J.; Smith, Rick; Li, Wei

    2015-01-01

    Results are presented here from an experimental investigation that was performed to evaluate the inside condensation and evaporation heat transfer of R410A, R22 and R32 that took place in a 12.7 mm (0.5 in) O.D. horizontal copper tube at low mass fluxes. Tubes considered in this evaluation consisted of a smooth tube (inner diameter 11.43 mm) and a newly developed enhanced surface Vipertex™ 1EHT tube. Heat transfer enhancement is an important factor in obtaining energy efficiency improvements in a variety of heat transfer applications. Utilization of enhanced heat transfer tubes is often utilized in the development of high performance air conditioning and refrigeration systems. Vipertex™ has designed and produced these surfaces through three dimensional material surface modifications which produces flow optimized, enhanced heat transfer tubes that increase heat transfer. Heat transfer enhancement plays an important role in improving energy efficiencies and developing high performance thermal systems. This study details the evaluation of the in-tube evaporation and condensation that takes place in these tubes over a wide range of conditions. The test apparatus utilized included a straight horizontal test section with an active length heated by water circulated in the surrounding annulus. Constant heat flux was maintained and refrigerant quality varied. In-tube evaporation measurements of R22, R32 and R410A are reported for evaporation at 10 °C with mass flow rates in the range of 15–40 kg h"−"1. Single phase measurements are reported for mass flow rates from 15 kg h"−"1 to 80 kg h"−"1. Condensation tests were conducted at a saturation temperature of 47 °C, with an inlet quality of 0.8 and an outlet quality of 0.1. In a comparison to smooth tubes, the average heat transfer coefficients for the Vipertex 1EHT tube exceeded those of a smooth tube. Average evaporation and condensation heat transfer coefficients for R22, R32 and R410A in the 1EHT

  10. The structure and physical-mechanical properties of the heat-resistant Ni-Co-Cr-Al-Y intermetallic coating obtained using rebuilt plasma equipment

    Science.gov (United States)

    Tarasenko, Yu. P.; Tsareva, I. N.; Berdnik, O. B.; Fel, Ya. A.; Kuzmin, V. I.; Mikhalchenko, A. A.; Kartaev, E. V.

    2014-12-01

    Results of a study of the structure, physico-mechanical properties, and the resistance to heat of Ni-Co-Cr-Al-Y intermetallic coatings obtained by powder spraying on the standard UPU-3D plasma spray facility (plasmatron with self-establishing arc length) and on the rebuilt facility equipped with the enhanced-power PNK-50 plasmatron with sectionalized inter-electrode insert, are reported. Coatings of higher density ( ρ = 7.9 g/cm3) and higher microhardness (H μ = 770 kg-force/mm2) with lower porosity values ( P = 5.7 %, P c = 5.1 %, and P 0 = 0.6 %) and high resistance to heat ((M - M0)/M0 = 1.2) were obtained. The developed coating is intended for protection of the working surfaces of turbine engine blades in gas-turbine power plants.

  11. Antioxidant and Anti-Inflammatory Activities of Hydrolysates and Peptide Fractions Obtained by Enzymatic Hydrolysis of Selected Heat-Treated Edible Insects

    OpenAIRE

    Zielińska, Ewelina; Baraniak, Barbara; Karaś, Monika

    2017-01-01

    This study investigated the effect of heat treatment of edible insects on antioxidant and anti-inflammatory activities of peptides obtained by in vitro gastrointestinal digestion and absorption process thereof. The antioxidant potential of edible insect hydrolysates was determined as free radical-scavenging activity, ion chelating activity, and reducing power, whereas the anti-inflammatory activity was expressed as lipoxygenase and cyclooxygenase-2 inhibitory activity. The highest antiradical...

  12. Flow patterns and heat transfer characteristics of flat plate pulsating heat pipes with various asymmetric and aspect ratios of the channels

    International Nuclear Information System (INIS)

    Jang, Dong Soo; Lee, Joo Seong; Ahn, Jae Hwan; Kim, Dongwoo; Kim, Yongchan

    2017-01-01

    Highlights: • Flat plate pulsating heat pipes with asymmetric and aspect ratios were tested. • Flow patterns were investigated according to channel geometry and flow condition. • Heat transfer characteristics were analyzed with various heat inputs. • Optimum asymmetric and aspect ratios were suggested for maximum thermal performance. - Abstract: The thermal performance of flat plate pulsating heat pipes (PHPs) in compact electronic devices can be improved by adopting asymmetric channels with increased pressure differences and an unbalanced driving force. The objective of this study is to investigate the heat transfer characteristics of flat plate PHPs with various asymmetric ratios and aspect ratios in the channels. The thermal performance and flow pattern of the flat plate PHPs were measured by varying the asymmetric ratio from 1.0 to 4.0, aspect ratio from 2.5 to 5.0, and heat input from 2 to 28 W. The effects of the asymmetric ratio and aspect ratio on the thermal resistance were analyzed with the measured evaporator temperature and flow patterns at various heat inputs. With heat inputs of 6 W and 12 W, the optimum asymmetric ratio and aspect ratio for the flat plate PHPs were determined to be 4.0 and 2.5, respectively. With the heat input of 18 W, the optimum asymmetric ratio and aspect ratio were determined to be 1.5 and 2.5, respectively.

  13. Effect of Activation Temperature and Heating Duration on Physical Characteristics of Activated Carbon Prepared from Agriculture Waste

    Directory of Open Access Journals (Sweden)

    Tham Yee Jun

    2010-01-01

    Full Text Available This study was conducted to determine the physical characteristics of activated carbon prepared from durian shell in varied heating durations from 10 min to 30 min and activation temperatures of 400C and 500C. Durian shells have been characterized in term of ultimate and proximate analysis, chemical composition and thermal behaviour with a view to be used as activated carbon precursor. Durian shell activated carbon was prepared by impregnating 10g of sample in 10% (v/v concentration of phosphoric acid for 24 h, followed by carbonization at 400C and 500C with different heating durations under nitrogen atmosphere. The results showed that various treatment conditions affect the percentage of yield, BET surface area, micropore volume, and average pore diameter. The highest surface area (SBET 1024 m2/g was obtained at 500C and 20 min of heating duration with 63% of yield and 0.21 cm3/g micropore volume.

  14. Characteristics on the heat storage and recovery by the underground spiral heat exchange pipe; Chichu maisetsu spiral kan ni yoru chikunetsu shunetsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Imai, I [Kure National College of Technology, Hiroshima (Japan); Taga, M [Kinki University, Osaka (Japan)

    1996-10-27

    The consistency between the experimental value of a soil temperature and the calculation value of a soil temperature given by a non-steady heat conduction equation was confirmed. The experimental value is obtained by laying a spiral heat exchange pipe in the heat-insulated soil box and circulating hot water forcibly in the pipe. The temperature conductivity in soil significantly influences the heat transfer in soil. The storage performance is improved when the temperature conductivity increases because of the contained moisture. As the difference between the initial soil temperature and circulating water temperature becomes greater, the heat storage and recovery values increase. A thermal core heat transfer is done in the spiral pipe. Therefore, the diameter of the pipe little influences the heat storage performance, and the pitch influences largely. About 50 hours after heat is stored, the storage performance is almost the same as for a straight pipe that uses the spiral diameter as a pipe diameter. To obtain the same heat storage value, the spiral pipe is made of fewer materials than the straight pipe and low in price. The spiral pipe is more advantageous than the straight pipe in the necessary motive power and supply heat of a pump. 1 ref., 11 figs., 1 tab.

  15. AN EXPERIMENTAL ASSESSMENT OF THE PLATE HEAT EXCHANGER CHARACTERISTICS BY WILSON PLOT METHOD

    Directory of Open Access Journals (Sweden)

    Jan Opatřil

    2016-10-01

    Full Text Available An aim of this paper is suggestion of the evaluation method based on the experimental data and the Wilson plot method for the Plate Heat Exchangers (PHE. For the purpose of the project the new experimental loop was built for the testing of PHE to obtain the overhaul heat transfer coefficient and pressure drop between inlet and outlet of the fluid. The measurement were done for three different PHE with the performance range 30-100kW. The working fluid was water on both sides of the PHE. The differences are in number of pates as well as in extrusion profiles. The Wilson plot evaluation method was involved for the processing experimental data. To obtain more accurate correlations between the experimental data and theoretical results yield of the Wilson plot, the method was enhanced by the measured pressure drop involving. This approach could be useful for PHE designing software and for the manufacturing company.

  16. Optimum interior area thermal resistance model to analyze the heat transfer characteristics of an insulated pipe with arbitrary shape

    International Nuclear Information System (INIS)

    Chou, H.-M.

    2003-01-01

    The heat transfer characteristics for an insulated regular polygonal (or circular) pipe are investigated by using a wedge thermal resistance model as well as the interior area thermal resistance model R th =t/K s /[(1-α)A 2 +αA 3 ] with a surface area weighting factor α. The errors of the results generated by an interior area model can be obtained by comparing with the exact results generated by a wedge model. Accurate heat transfer rates can be obtained without error at the optimum α opt with the related t/R 2 . The relation between α opt and t/R 2 is α opt =1/ln(1+t/R 2 )-1/(t/R 2 ). The value of α opt is greater than zero and less than 0.5 and is independent of pipe size R 2 /R cr but strongly dependent on the insulation thickness t/R 2 . The interior area model using the optimum value α opt with the related t/R 2 should also be applied to an insulated pipe with arbitrary shape within a very small amount of error for the results of heat transfer rates. The parameter R 2 conservatively corresponds to the outside radius of the maximum inside tangent circular pipe within the arbitrary shaped pipes. The approximate dimensionless critical thickness t cr /R 2 and neutral thickness t e /R 2 of an insulated pipe with arbitrary shape are also obtained. The accuracies of the value of t cr /R 2 as well as t e /R 2 are strongly dependent on the shape of the insulated small pipe. The closer the shape of an insulated pipe is to a regular polygonal or circular pipe, the more reliable will the values of t cr /R 2 as well as t e /R 2 be

  17. Fat characteristics and fatty acid profile of sea cucumbers (Holothuria Scabra obtained from the coasts of the Bushehr province -Iran

    Directory of Open Access Journals (Sweden)

    Najmeh Jadavi

    2015-11-01

    Full Text Available Background: Sea cucumbers are belonging to echinoderms and one of the important members of the food chain in temperate ecosystems and tropical coral reefs. The medicinal and nutritional uses of these invertebrates are primordial and are important as ecological, biological and economic properties. Holothuria Scabra, as one of the most valuable commercial species of sea cucumber in the world, is the dominant species in many Persian Gulf coasts such as the Bushehr province coasts. Conspicuous characteristics such as the use of inexpensive foods in their culture, the rather rapid, easy and low cost growth and reproduction, the possibility of culture with other fish, reduce the organic substrate in pools, the broad tolerance in water factors changes such as salinity and temperature it has selected them to culture.It seems they are containing the significant amounts of nutrients, especially appreciated fatty acids. Therefore, the aims of the current study are determination of total fat content, quality and quantity evaluations of some physicochemical parameters such as acid value (AV, peroxide value (PV, and refractive index (RI as well as, identify the profile of fatty acids in the fat. Materials & Methods: In this study, after collecting the 36 samples of sea cucumbers from the coasts of the bushehr province, sample preparation, and extraction of fat, their fatty acids profile were analyzed using gas chromatography with flame ionization detector (GC-FID. Results: The peroxide and the acid values were 0.62±0.0435 and 0.7553±0.0034. The optical refractive index of the oil was 1467 at 26°C, and total fat was also 2%. Among 19 identified fatty acids obtained from the GC analysis of Holothuria Scabra oil, fatty acids: heneicosanoic acid, linoleic acid, palimitic acid, stearic acid, linoleic acid, and Meristic acid, with respectively amounts of 40.81%, 27.5%, 15.24%, 4.73%, 4.46% and 2.38% had the highest values, and other fatty acids were negligible

  18. An investigation into the effects of conventional heat treatments on mechanical characteristics of new hot working tool steel

    Science.gov (United States)

    Fares, M. L.; Athmani, M.; Khelfaoui, Y.; Khettache, A.

    2012-02-01

    The effects of conventional heat treatments, i.e. quenching and tempering, on the mechanical characteristics of non standard hot work tool steel, close to either AISI-H11/H13 are investigated. The major elemental composition differences are in carbon, silicon and vanadium. The objective of the carried heat treatments is to obtain an efficient tool performance in terms of hardness, wear resistance and mechanical strength. Experimental results allow an explanation of the surface properties depending mainly on both chemical composition and optimised preheating parameters. After austenitizing at 1050 °C for 15 min, the as-quenched steel in oil bath exhibited the fully martensitic structure (without bainite) connected to a small fraction of retained austenite and complex carbides mainly of M23C6 type. Twice tempering at 500 °C and 600 °C resulted in initiating the precipitation processes and the secondary hardness effect. As a result, carbide content amounted to 3% while the retained austenite content decreased to 0%. Accordingly, the required mechanical properties in terms of hardness and wear are fulfilled and are adequately favourable in handling both shocks and pressures for the expected tool life. Induced microstructures are revealed using optical and scanning electron microscopes. Phase compositions are assessed by means of X-ray diffraction technique while mechanical characteristics are investigated based on hardness and abrasive wear standard tests.

  19. On numerical heat transfer characteristic study of flat surface subjected to variation in geometric thickness

    Science.gov (United States)

    Umair, Siddique Mohammed; Kolawale, Abhijeet Rangnath; Bhise, Ganesh Anurath; Gulhane, Nitin Parashram

    Thermal management in the looming world of electronic packaging system is the most prior and conspicuous issue as far as the working efficiency of the system is concerned. The cooling in such systems can be achieved by impinging air jet over the heat sink as jet impingement cooling is one of the cooling technologies which are widely studied now. Here the modulation in impinging and geometric parameters results in the establishment of the characteristic cooling rate over the target surface. The characteristic cooling curve actually resembles non-uniformity in cooling rate. This non-uniformity favors the area average heat dissipation rate. In order to study the non-uniformity in cooling characteristic, the present study takes an initiative in plotting the local Nusselt number magnitude against the non-dimensional radial distance of the different thickness of target surfaces. For this, the steady temperature distribution over the target surface under the impingement of air jet is being determined numerically. The work is completely inclined towards the determination of critical value of geometric thickness below which the non-uniformity in the Nusselt profile starts. This is done by numerically examining different target surfaces under constant Reynolds number and nozzle-target spacing. The occurrences of non-uniformity in Nusselt profile contributes to over a 42% enhancement in area average Nusselt magnitude. The critical value of characteristic thickness (t/d) reported in the present investigation approximate to 0.05. Below this value, the impingement of air jet generates a discrete pressure zones over the target surface in the form of pressure spots. As a result of this, the air flowing in contact with the target surface experiences a damping potential, in due of which it gets more time and contact with the surface to dissipate heat.

  20. Characteristics of entropy generation and heat transfer in double-layered micro heat sinks with complex structure

    International Nuclear Information System (INIS)

    Zhai, Y.L.; Xia, G.D.; Liu, X.F.; Wang, J.

    2015-01-01

    Highlights: • A novel DL-MCHS with complex structure is presented. • A model of entropy generation rate of DL-MCHSs is derived from the first and second laws of thermodynamics. • DL-MCHSs show better thermodynamic advantage and thermal performance under large volumetric flow rate. - Abstract: A new type of double-layered micro heat sink (DL-MCHS) with complex structure is designed and investigated numerically. Moreover, a model of entropy generation rate of DL-MCHSs is also derived from the first and second laws of thermodynamics. Results for the relationship of entropy generation rate between the first and second layer of DL-MCHSs, total entropy generation rate, the average temperature on the bottom wall, thermal resistance and pressure drop are investigated in detail, respectively. The results indicate that the effect of entropy generation rate of the first layer on total entropy generation rate is dominant. The thermal characteristic of DL-MCHSs with complex structure is better than that of all DL-MCHSs and single-layered micro heat sinks (SL-MCHSs) with simple structure under the same volumetric flow rate. However, DL-MCHSs only show better thermodynamic advantage and thermal performance than SL-MCHSs with complex structure when the volumetric flow rate larger than a certain value. It is not reasonable to use DL-MCHSs for cooling microelectronic equipments under small volumetric flow rate due to the larger irreversibility. Finally, the pressure drop of DL-MHCSs can be reduced by properly changing the channel height under various volumetric flow rates. Due to the less irreversibility and more uniform temperature distribution on the bottom wall, DL-MCHSs can effectively eliminate the internal thermal stresses in microelectronic equipments. Therefore, DL-MCHSs are an alternative method for the electronic cooling. Moreover, the thermodynamic analysis provides references for the actual application design

  1. Study of parameters of heat treatment in obtaining glass ceramic materials with addition of the industrial waste

    International Nuclear Information System (INIS)

    Kniess, C.T.; Prates, P.B.; Martins, G.J.M.; Riella, H.G.; Matsinhe, Jonas; Kuhnen, N.C.

    2012-01-01

    The production of materials from crystallization of glass, called glass ceramic, have proved interesting by the possibility of development of different microstructures, with reduced grain size and the presence of residual amorphous phase in different quantities. The method that uses the differential thermal analysis (DTA) provides research on the material properties over a wide temperature range, it's widely applied to crystallization processes of glass ceramic materials. Within this context, this paper aims to study the kinetics of nucleation and crystal growth in glass ceramic materials in the system SiO 2 - Al 2 O 3 -Li 2 O, obtained with the addition of mineral coal bottom ash as source of aluminosilicates, through the technique of differential thermal analysis. (author)

  2. Fundamental characteristics of heat conduction enhancement in oscillating viscous flow-dream pipe

    International Nuclear Information System (INIS)

    Katsuta, M.; Nagata, K.; Maruyama, Y.; Tsujimori, A.

    1991-01-01

    This paper reports that to confirm the heat conduction augmentation technique via sinusoidal oscillation experimentally and to establish a fundamental data base of this device, systematic measurements using almost identically scaled with Kurzweg's apparatus for demonstration were conducted. In this heat exchanger, the fluid occupied a capillary tube or its bundle that connected two reservoirs at different temperature; a special constructed oscillation driving unit generated a pulsed motion of working fluid. Operation took place at various tube diameters, oscillated frequency and stroke using pure water and ethanol as working liquid. As a result, a new factor so-called heat transport coefficient which indicates the heat transfer rate multiplying temperature gradient between hot and cold reservoir was introduced. This factor increased with increasing oscillated frequency and stroke, however, beyond a critical frequency, this trend disappeared. Using modified Reynolds number and stroke ratio, a new empirical formula which correlated the data regardless of the difference of working liquid was proposed. A discussion of tube bundle was also made using this correlation. Finally, an attempt was performed to correlate the data using effective thermal diffusivity predicted by simple lumped capacitance analysis and characteristic period

  3. Effect of heat transfer tube leak on dynamic characteristic of steam generator

    International Nuclear Information System (INIS)

    Sun Baozhi; Shi Jianxin; Li Na; Zheng Lusong; Liu Shanghua; Lei Yu

    2015-01-01

    Taking the steam generator of Daya Bay Nuclear Power Station as the research object, one-dimensional dynamic model of the steam generator based on drift flux theory and leak model of heat transfer tube were established. Steady simulation of steam generator under different conditions was carried out. Based on verifying the drift flux model and leak model of heat transfer tube, the effect of leak location and flow rate under different conditions on steam generator's key parameters was studied. The results show that the drift flux model and leak model can reflect the law of key parameter change accurately such as vapor mass fraction and steam pressure under different leak cases. The variation of the parameters is most apparent when the leak is at the entrance of boiling section and vapor mass fraction varies from 0.261 to 0.163 when leakage accounts for 5% of coolant flow rate. The successful prediction of the effect of heat transfer tube leak on dynamic characteristics of the steam generator based on drift flux theory supplies some references for monitoring and taking precautionary measures to prevent heat transfer tube leak accident. (authors)

  4. Visual Observation of Bubble Departure Characteristics in the Nano-particle Coated Heating Surface

    International Nuclear Information System (INIS)

    Han, Won Soek; Yoo, Shin; Lee, Jae Young

    2010-01-01

    Although the great enhancement of the thermal conductivity of the nanofluids, the fluid mixed with small amount of the nano meter sized particles, has been known, many experimental data of the boiling heat transfer reported degraded heat transfer rate than the fresh fluid. However, the great enhancement of the critical heat flux in nanofluids has been reported by many investigators. Due to the opaque scattering of the nano particles in nano fluids, direct observation of the bubble dynamics in the boiling process has not been made. However, it has been known that the boiling heat transfer characteristics of the heater coated by the nano particles in the fresh water are almost similar to that in the nano fluid. Recently, consensus has been made in the understanding of the CHF enhancement of nanofluids or nano-particle coated heater as the surface phenomena. Therefore, in the present paper, we do experimental study to observe the bubble departure in the pool boiling process with the nano-particle coated heater

  5. Heating value characteristics of sewage sludge: a comparative study of different sludge types

    International Nuclear Information System (INIS)

    Kim, Young-JU.; Kang, Hae-Ok.; Qureshi, T.I.

    2005-01-01

    Heating value characteristics of three different types of sludge, i.e. domestic sewage sludge, industrial sludge, and industrial + domestic sewage sludge were investigated. Industrial + domestic sewage sludge (thickened) showed the highest heating value (5040 kcal/kg) than other sludge types. This may be due to increased amount of organic matter presents in thickened sludge than de-watered sludge. A gradual increase in organic matter of the sludge was observed with the increase of the moisture contents. Heating value of the sludge having 60% moisture contents was found in the range between 924-1656 kcal/kg and this amount was higher than the minimum heating value (800 kcal/kg) required sustaining auto thermal combustion in sludge incineration process. Energy consumption requirement for pre drying sludge operations revealed that industrial sludge (de-watered) required the minimum cost (13 $/ton of sludge) to make it a sludge of fuel grade (60% W), while mixed sludge cost the highest amount for its pre-drying operations. (author)

  6. Flow induced vibration characteristics in 2X3 bundle critical heat flux experiment

    International Nuclear Information System (INIS)

    Kim, Dae Hun; Chang, Soon Heung

    2005-01-01

    Above a certain heat flux, the liquid can no longer permanently wet the heater surface. This situation leads to an inordinate decrease in the surface heat transfer. This heat flux is commonly referred to as the critical heat flux (CHF). The CHF in nuclear reactors is one of the important thermal hydraulic parameters limiting the available power. Flow induced vibration (FIV) is the vibration caused by a fluid flowing around a body. In the fluid flowing system, FIV occurred by structures and flow condition. Many structures in nuclear power plant system are designed to prevent from structure failure due to FIV. Recently, Hibiki and Ishii (1998) carried out an experimental investigation on the effect of flow-induced vibration (FIV) on two-phase flow structure in vertical tube and reported that the FIV drastically changed the void fraction profiles. The void fraction profiles is one of the important parameter for determining CHF. Therefore, the investigation on the effect of FIV on CHF are needed. The research on FIV characteristics detection during CHF experiment in 2X3 bundle using R-134a has been carried out in KAIST. Using the results new FIV correlation in 2-pahse turbulent flow are suggested after finding out relation between CHF and dynamic pressure fluctuation value

  7. Heat transfer and friction characteristics in steam cooled rectangular channels with rib turbulators

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Jianying; Gao, Tieyu; Li, Guojun [Xi' an Jiaotong University, Xi' an (China)

    2014-01-15

    We studied the heat transfer and friction characteristics in steam-cooled rectangular channels with rib turbulators on W side or H side walls in the Reynolds number (Re) range of 10000-80000. Each of the test channels was welded by four stainless steel plates to simulate the actual geometry and heat transfer structure of blade/vane internal cooling passage. The length of the channel L was 1000 mm, the cross section of the channel was 40 mm X 80 mm, and the pitch-to-rib height ratio p/e was kept at 10. The channel blockage ratio (W/H) was 0.047. Results showed that the Nusselt number (Nu) distributions displayed different trends at the entrance region with the increase of Re for the rib turbulators on the W side walls. The heat transfer performance of the rib turbulators on the H side walls was about 24- 27% higher than that on the W side walls at the same pumping power. In addition, semi-empirical correlations for the two cases, rib turbulators on W side walls and rib turbulators on H side walls, were developed based on the heat transfer results, which could be used in the design of the internal cooling passage of new generation steam-cooled gas turbine blade/vane.

  8. Investigation on flow and heat transfer characteristics in rectangular channel with drop-shaped pin fins

    Directory of Open Access Journals (Sweden)

    Fengming Wang

    2012-12-01

    Full Text Available The flow and heat transfer characteristics inside a rectangular channel embedded with pin fins were numerically and experimentally investigated. Several differently shaped pin fins (i.e., circular, elliptical, and drop-shaped with the same cross-sectional areas were compared in a staggered arrangement. The Reynolds number based on the obstructed section hydraulic diameter (defined as the ratio of the total wetted surface area to the open duct volume available for flow was varied from 4800 to 8200. The more streamlined drop-shaped pin fins were better at delaying or suppressing separation of the flow passing through them, which decreased the aerodynamic penalty compared to circular pin fins. The heat transfer enhancement of the drop-shaped pin fins was less than that of the circular pin fins. In terms of specific performance parameters, drop-shaped pin fins are a promising alternative configuration to circular pin fins.

  9. Water loop heat pump and its characteristics%水环热泵及其特点

    Institute of Scientific and Technical Information of China (English)

    冯润娣

    2011-01-01

    This paper introduces the definition and working principle of water loop beat pump, and describes its development condition at home and abroad. Through analyzing the characteristics of water loop heat pump, it points out the water loop heat pump is a kind of economic, energy saving and environment protection air-conditioning system, and has great application prospect.%阐述了水环热泵的定义及工作原理,介绍了水环热泵在国内外的发展概况,通过分析水环热泵的特点,指出其是一种经济、节能、环保的空调系统,有着广阔的应用前景。

  10. Enhancement of methane gas sensing characteristics of graphene oxide sensor by heat treatment and laser irradiation.

    Science.gov (United States)

    Assar, Mohammadreza; Karimzadeh, Rouhollah

    2016-12-01

    The present study uses a rapid, easy and practical method for cost-effective fabrication of a methane gas sensor. The sensor was made by drop-casting a graphene oxide suspension onto an interdigital circuit surface. The electrical conductivity and gas-sensing characteristics of the sensor were determined and then heat treatment and in situ laser irradiation were applied to improve the device conductivity and gas sensitivity. Real-time monitoring of the evolution of the device current as a function of heat treatment time revealed significant changes in the conductance of the graphene oxide sensor. The use of low power laser irradiation enhanced both the electrical conductivity and sensing response of the graphene oxide sensor. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Numerical Investigation of Deviation of Phase Change Characteristics of Horizontal and Vertical Flat Heat Pipe Configurations

    Directory of Open Access Journals (Sweden)

    Rakesh Hari

    2015-12-01

    Full Text Available The flow characteristics in the porous wick of a flat heat pipe subjected to boiling and condensation are analysed here using two-phase mixture model. Steady laminar boundary layer flow in the capillary wick structure is considered for both vertical and horizontal orientations. The governing boundary layer partial differential equations are simplified using similarity transformation. The transformed equations are then solved numerically by using shooting iterative technique. Investigation was carried out for the effects of the involved parameters such as saturation and temperature across the boundary layer. The behaviour of non-dimensional numbers due to the orientation of the heat pipe is also discussed. The study confirms that orientation plays a significant role in flow and temperature field.

  12. Experiments on the Heat Transfer and Natural Circulation Characteristics of the Passive Residual Heat Removal System for the Advanced Integral Type Reactor

    International Nuclear Information System (INIS)

    Park, Hyun-Sik; Choi, Ki-Yong; Cho, Seok; Park, Choon-Kyung; Lee, Sung-Jae; Song, Chul-Hwa; Chung, Moon-Ki; Lee, Un-Chul

    2004-01-01

    Experiments on the heat transfer characteristics and natural circulation performance of the passive residual heat removal system (PRHRS) for the SMART-P have been performed using the high temperature/high pressure thermal-hydraulic test facility (VISTA). The VISTA facility consists of the primary loop, the secondary loop, the PRHRS loop, and auxiliary systems to simulate the SMART-P, a pilot plant of the SMART. The primary loop is composed of the steam generator (SG) primary side, a simulated core, a main coolant pump, and loop piping, and the PRHRS loop consists of the SG secondary side, a PRHRS heat exchanger, and loop piping. The natural circulation performance of the PRHRS, the heat transfer characteristics of the PRHRS heat exchangers and the emergency cooldown tank (ECT), and the thermal-hydraulic behavior of the primary loop are intensively investigated. The experimental results show that the coolant flows steadily in the PRHRS loop and the heat transfers through the PRHRS heat exchanger and the emergency cooldown tank are sufficient enough to enable the natural circulation of the coolant. The results also show that the core decay heat can be sufficiently removed from the primary loop with the operation of the PRHRS. (authors)

  13. Characteristics of low-frequency oscillation intensity of airsea turbulent heat fluxes over the northwest Pacific

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on the daily turbulent heat fluxes and related meteorological variables datasets (1985-2006) from Objectively Analyzed air-sea Fluxes (OAFlux) Project of Woods Hole Oceanographic Institution (WHOI), characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific are analyzed by linear perturbation method and correlation analysis. It can be concluded that: 1) the distribution of low-frequency oscillation intensity of latent heat flux (LHF) over the northwest Pacific is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea humidity gradient (Δq′) as well as mean air-sea humidity gradient ( Δ q), while the distribution of low-frequency oscillation intensity of sensible heat flux (SHF) is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea temperature gradient (ΔT′). 2) The low-frequency oscillation of turbulent heat fluxes over the northwest Pacific is the strongest in winter and the weakest in summer. And the seasonal transition of low-frequency oscillation intensity of LHF is jointly influenced by those of low-frequency oscillation intensity of Δq′, low-frequency oscillation intensity of anomalous wind speed (U′), Δ q and mean wind speed (U ), while the seasonal transition of low-frequency oscillation intensity of SHF is mainly influenced by those of low-frequency oscillation intensity of ΔT′ and U . 3) Over the tropical west Pacific and sea areas north of 20°N, the low-frequency oscillation of LHF (SHF) is mainly influenced by atmospheric variables qa′ (Ta′) and U′, indicating an oceanic response to overlying atmospheric forcing. In contrast, over the tropical eastern and central Pacific south of 20°N, qs′ (Ts′) also greatly influences the low-frequency oscillation of LHF (SHF).

  14. Predictability and Spatial Characteristics of New-York-City-Area Heat Waves

    Science.gov (United States)

    Raymond, C.; Horton, R. M.

    2016-12-01

    The origins, characteristics, and predictability of extreme heat waves in the Northeast U.S. are simultaneously examined at multiple scales, using hourly observational data from 1948-2014 and focusing in particular on the region surrounding New York City. A novel definition of heat waves - incorporating both temperature and moisture at hourly resolution - is used to identify 3-to-5-day heat waves whose dynamics are then analyzed from 3 weeks prior to 3 weeks subsequent to the event. Inter-event differences in dynamics such as the strength and position of geopotential-height anomalies; the strength, persistence, and orientation of sea breezes; and the dominant 850-hPa wind azimuth, all of which are filtered via local terrain and land-use to create differences in conditions between events at specific locations. In particular, using composite maps and back trajectories, they are found to play an important role in creating mesoscale differences in low-level moisture content, from one side of the metropolitan area to the other. Evidence is presented supporting the influence of coastline orientation in explaining the differences in the relationships between wind azimuth and temperature & moisture advection between New York City proper and northern New Jersey. Self-organizing maps are employed to classify heat waves based on the small-scale differences in temperature and moisture between events, and the results of this classification are then used in correlations with synoptic- and hemispheric-scale geopotential-height anomalies. Considerable predictability of event type on the small-scale (as well as occurrence of a heat wave of any kind) is found, originating primarily from central Pacific and western Atlantic SSTs.

  15. Autoignition characteristics of laminar lifted jet flames of pre-vaporized iso-octane in heated coflow air

    KAUST Repository

    Al-Noman, Saeed M.; Choi, Sang Kyu; Chung, Suk-Ho

    2015-01-01

    The stabilization characteristics of laminar non-premixed jet flames of pre-vaporized iso-octane, one of the primary reference fuels for octane rating, have been studied experimentally in heated coflow air. Non-autoignited and autoignited lifted

  16. Influencing factors on as-cast and heat treated 400-18 ductile iron grade characteristics

    Directory of Open Access Journals (Sweden)

    I. Riposan

    2007-11-01

    Full Text Available As-cast and heat-treated 400-18 ductile iron (DI grade was obtained in different foundry conditions, as metallic charge, Mg-treatment alloy and inoculation. It was found that the Pearlitic Influence Factor (Px and Antinodulizing Complex Factor (K1 have an important influence on property of DI, depending on the Mn and P level, the metallurgical quality of iron melt, rare earth (RE and inoculation. It was also found that the influence of Mn is depended on the phosphorus and residual elements level in ductile iron. Less than 0.03%P and 0.2%Mn and Px2.0 determines presence of pearlite in as-cast structure, while ferrite structure is obtained after a short annealing heat treatment. Lower level of phosphorus (P1.2. Si has a significant influence on the mechanical properties of heat treated ductile irons: an important decreasing of elongation level and a moderate increasing of yield and tensile strength and their ratio in 150-170 HB typical hardness field. A typical final chemical composition for as-cast 400-18 ductile iron could include 3.5%-3.7%C, 2.4%-2.5%Si, max.0.18%Mn, max.0.025%P, max.0.01%S, 0.04%-0.05%Mgres. for Px<1.5 and K1<1.1. High purity pig iron, RE-bearing FeSiMg and powerful inoculant are also recommended.

  17. Trial production of ceramic heat storage unit and study on thermal properties and thermal characteristics of the heat storage unit. Mixed salts of Na2CO3, MgCl2 and CaCl2 as heat storage medium

    International Nuclear Information System (INIS)

    Shiina, Yasuaki

    1998-12-01

    Heat storage technique of high temperature and high density latent heat can be applied to an accumulator of heat generated by nuclear power plant in the night and to a thermal load absorber. For the practical use of the heat storage technique, it is important to improve heat exchange characteristics between heat storage medium, such as molten salts, and heat transfer fluid because of low thermal conductivity of the molten salts, to improve durability among molten salt and structure materials and to develop the molten salt with stable thermal properties for a long period. Considering the possibility for the improvement of heat exchange characteristics of phase change heat storage system by absorbing molten salt in porous ceramics with high thermal conductivity, high temperature proof and high resistance to corrosion, several samples of the ceramics heat storage unit were made. Basic characteristics of the samples (strength, thermal properties, temperature characteristics during phase change) were measured experimentally and analytically to study the utility and applicability of the samples for the heat storage system. The results show that the heat storage unit should be used in inactive gas condition because water in the air absorbed in the molten salts would yield degeneration of properties and deterioration of strength and that operation temperature should be confined near fusion temperature because some molten salts would be vaporized and mass would be decreased in considerable high temperature. The results also show that when atmospheric temperature changes around the melting temperature, change in ceramic temperature becomes small. This result suggests the possibility that ceramic heat storage unit could be used as thermal load absorber. (J.P.N.)

  18. Tests of the heat transfer characteristic of air cooler during cooling by natural convection of the Fast Breeder Reactor plants

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-08-15

    The purpose of this study is to confirm the heat transfer characteristics of the air cooler (AC) of the Fast Breeder Reactor(FBR) which has a function to remove the residual heat of the reactor by heat exchange between sodium and air in natural convection region if electric power would be lost. In order to confirm the characteristics of the AC installed in the FBR plant, the heat transfer test by using the AC which is installed in the sodium test loop owned by Toshiba Corporation has been planned. In this study, the heat transfer characteristic tests were performed by using the AC in sodium test loop, and the CFD analyses were conducted to evaluate the test results and the heat transfer characteristics of the plant scale AC at the condition of natural convection. In addition, the elemental tests to confirm the influence of the heat transfer tube placement by using the heat transfer tube of the same specification as the AC of Monju were performed. (author)

  19. Demographic And Histopathological Characteristics Of Colorectal Polyps: A Descriptive Study Based On Samples Obtained From Symptomatic Patients

    Directory of Open Access Journals (Sweden)

    Cekodhima Genta

    2016-06-01

    Full Text Available Colorectal polyps (CP are common among individuals older than 50 years. Some polyp types can precede colorectal cancer (CRC. This study aimed at describing histopathological characteristics of colorectal polyps in relation to age and gender among symptomatic patients referred for a colonoscopy examination during 2011-2014 in Tirana, Albania.

  20. Fouling reduction characteristics of a no-distributor-fluidized-bed heat exchanger for flue gas heat recovery

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Y.D.; Lee, K.B.; Islam, S.Z.; Ko, S.B. [Kongju National University, Kong Ju (Republic of Korea). Dept. for Mechanical Engineering

    2008-07-01

    In conventional flue gas heat recovery systems, the fouling by fly ashes and the related problems such as corrosion and cleaning are known to be major drawbacks. To overcome these problems, a single-riser no-distributor-fluidized-bed heat exchanger is devised and studied. Fouling and cleaning tests are performed for a uniquely designed fluidized bed-type heat exchanger to demonstrate the effect of particles on the fouling reduction and heat transfer enhancement. The tested heat exchanger model (1 m high and 54 mm internal diameter) is a gas-to-water type and composed of a main vertical tube and four auxiliary tubes through which particles circulate and transfer heat. Through the present study, the fouling on the heat transfer surface could successfully be simulated by controlling air-to-fuel ratios rather than introducing particles through an external feeder, which produced soft deposit layers with 1 to 1.5 mm thickness on the inside pipe wall. Flue gas temperature at the inlet of heat exchanger was maintained at 450{sup o}C at the gas volume rate of 0.738 to 0.768 CMM (0.0123 to 0.0128 m{sup 3}/sec). From the analyses of the measured data, heat transfer performances of the heat exchanger before and after fouling and with and without particles were evaluated. Results showed that soft deposits were easily removed by introducing glass bead particles, and also heat transfer performance increased two times by the particle circulation. In addition, it was found that this type of heat exchanger had high potential to recover heat of waste gases from furnaces, boilers, and incinerators effectively and to reduce fouling related problems.

  1. Experimental study on the effects of the number of heat exchanger modules on thermal characteristics in a premixed combustion system

    International Nuclear Information System (INIS)

    Yu, Byeonghun; Lee, Chang-Eon; Kum, Sung Min; Lee, Seungro

    2016-01-01

    The effects of the number of heat exchanger modules on thermal characteristics were experimentally studied in a premixed combustion system with a cross-flow staggered-tube heat exchanger. The various heat exchanger modules, from 4 to 8, combined with a premixed burner were tested to investigate the performance of the heat exchanger through the surface area of the heat exchanger at various equivalence ratios. Additionally, the performance of the heat exchanger was analyzed by applying entropy generation theory to the heat exchanger system. As a result, although the heat transfer rate increases with the increase of the equivalence ratio, the NOx and CO concentrations also increase due to the increasing flame temperature. In addition, the entropy generation increases with an increase of the equivalence ratio. Furthermore, the heat transfer rate and the effectiveness are increased with the increase of the number of the heat exchanger modules. Also, the effectiveness is sharply increased when the number of the heat exchanger modules is increased from 4 to 5. Consequently, the optimal operating conditions regarding pollutant emission, effectiveness and entropy generation in this experimental range are 0.85 for the equivalence ratio and 8 for the number of heat exchanger modules

  2. SWIFT BAT Loop Heat Pipe Thermal System Characteristics and Ground/Flight Operation Procedure

    Science.gov (United States)

    Choi, Michael K.

    2003-01-01

    The SWIFT Burst Alert Telescope (BAT) Detector Array has a total power dissipation of 208 W. To meet the stringent temperature gradient and thermal stability requirements in the normal operational mode, and heater power budget in both the normal operational and safehold modes, the Detector Array is thermally well coupled to eight constant conductance heat pipes (CCHPs) embedded in the Detector Array Plate (DAP), and two loop heat pipes (LHPs) transport heat fiom the CCHPs to a radiator. The CCHPs have ammonia as the working fluid and the LHPs have propylene as the working fluid. Precision heater controllers, which have adjustable set points in flight, are used to control the LHP compensation chamber and Detector Array XA1 ASIC temperatures. The radiator has the AZ-Tek AZW-LA-II low-alpha white paint as the thermal coating and is located on the anti-sun side of the spacecraft. This paper presents the characteristics, ground operation and flight operation procedures of the LHP thermal system.

  3. Temperature dependent electrical characteristics of an organic-inorganic heterojunction obtained from a novel organometal Mn complex

    International Nuclear Information System (INIS)

    Ocak, Y.S.; Ebeoglu, M.A.; Topal, G.; Kilicoglu, T.

    2010-01-01

    This study includes synthesizing a Mn hexaamide (MnHA) organometal compound (C 27 H 21 N 9 O 6 MnCl 2 ).(1/2H 2 O), fabrication of MnHA/n-Si organic-inorganic heterojunction and analysis of conduction mechanism of the device over the room temperature. After synthesizing the molecule, the structure of the compound was determined using spectroscopic methods. The Sn/MnHA/n-Si structure was constructed by forming a thin MnHA layer on n-Si inorganic semiconductor and evaporating Sn metal on organic complex. The structure has shown good rectifying behavior and obeys the thermionic emission theory. The current-voltage (I-V) characteristics of the diode have been measured at temperatures ranging from 300 to 380 K at 10 K intervals to determine the temperature dependent electrical characteristics of the device.

  4. Effect of Discrete Fracture Network Characteristics on the Sustainability of Heat Production in Enhanced Geothermal Reservoirs

    Science.gov (United States)

    Riahi, A.; Damjanac, B.

    2013-12-01

    Viability of an enhanced or engineered geothermal reservoir is determined by the rate of produced fluid at production wells and the rate of temperature drawdown in the reservoir as well as that of the produced fluid. Meeting required targets demands sufficient permeability and flow circulation in a relatively large volume of rock mass. In-situ conditions such overall permeability of the bedrock formation, magnitude and orientation of stresses, and the characteristics of the existing Discrete Fracture Network (DFN) greatly affect sustainable heat production. Because much of the EGS resources are in formations with low permeability, different stimulation techniques are required prior to the production phase to enhance fluid circulation. Shear stimulation or hydro-shearing is the method of injecting a fluid into the reservoir with the aim of increasing the fluid pressure in the naturally fractured rock and inducing shear failure or slip events. This mechanism can enhance the system's permeability through permanent dilatational opening of the sheared fractures. Using a computational modeling approach, the correlation between heat production and DFN statistical characteristics, namely the fracture length distribution, fracture orientation, and also fracture density is studied in this paper. Numerical analyses were completed using two-dimensional distinct element code UDEC (Itasca, 2011), which represents rock masses as an assembly of interacting blocks separated by fractures. UDEC allows for simulation of fracture propagation along the predefined planes only (i.e., the trajectory of the hydraulic fracture is not part of the solution of the problem). Thus, the hydraulic fracture is assumed to be planar, aligned with the direction of the major principal stress. The pre-existing fractures were represented explicitly. They are discontinuities which deform elastically, but also can open and slip (Coulomb slip law) as a function of pressure and total stress changes. The fluid

  5. [The obtainment and characteristics of Kalanchoe pinnata L. plants expressing the artificial gene of the cecropin P1 antimicrobial peptide].

    Science.gov (United States)

    Zakharchenko, N S; Rukavtsova, E B; Shevchuk, T V; Furs, O V; Pigoleva, S V; Lebedeva, A A; Chulina, I A; Baidakova, L K; Bur'yanov, Ya I

    2016-01-01

    Kalanchoe pinnata L. plants bearing an artificial CP1 gene encoding the cecropin P1 antimicrobial peptide have been obtained. The presence of the CP1 gene in the plant genome has been confirmed by PCR. Cecropin P1 synthesis in transgenic plants has been shown by MALDI mass spectrometry and Western blotting. The obtained plants have been highly resistant to bacterial and fungal phytopathogens, and their extracts have demonstrated antimicrobial activity towards human and animal pathogens. It has been shown that transgenic plants bearing the CP1 gene can be colonized by the beneficial associative microorganisms Methylovorus mays.

  6. Impact of the Flame-Holder Heat-Transfer Characteristics on the Onset of Combustion Instability

    KAUST Repository

    Hong, Seunghyuck

    2013-10-03

    In this article, we investigate the impact of heat transfer between the flame and the flameholder on the dynamic stability characteristics of a 50-kW backward-facing step combustor. We conducted a series of tests where two backward step blocks were used, made of ceramic and stainless steel, whose thermal conductivities are 1.06 and 12 W/m/K, respectively. Stability characteristics of the two flame-holder materials were examined using measurements of the dynamic pressure and flame chemiluminescence over a range of operating conditions. Results show that with the ceramic flameholder, the onset of instability is significantly delayed in time and, for certain operating conditions, disappears altogether, whereas with the higher conductivity material, the combustor becomes increasingly unstable over a range of operating conditions. We explain these trends using the heat flux through the flameholder and the change in the burning velocity near the step wall. Results suggest a potential approach using low-thermal-conductivity material near the flame-holder as passive dynamics suppression methods. Copyright © Taylor & Francis Group, LLC.

  7. The overall heat transfer characteristics of a double pipe heat exchanger: comparison of experimental data with predictions of standard correlations

    International Nuclear Information System (INIS)

    Mehrabian, M. A.; Mansouri, S. H.; Sheikhzadeh, G. A.

    2002-01-01

    The single-phase flow and thermal performance of a double pipe heat exchanger are examined by experimental methods. The working fluid is water at atmospheric pressure. Temperature measurements at the inlet and outlet of the two streams and also at an intermediate point half way between the inlet and outlet is made, using copper-constantan thermocouple wires. Mass flow rates for each stream are also measured using calibrated ratemeters. Heat is supplied to the inner tube stream by an immersion heater. The overall heat transfer coefficients are inferred from the measured data. The heat transfer coefficient of the inner tube flow (circular cross section) is calculated using the standard correlations. The heat transfer coefficient of the outer tube flow (annular cross section) is then deduced.Higher heat transfer coefficients are reported in the laminar flow regime in comparison to the predictions of standard correlations for straight and smooth tubes. The reasons for this discrepancy are identified and discussed. Experimental errors in measuring temperatures and mass flow rates are studied and their effects on the heat transfer coefficients are estimated. Experimental results for the range of operating conditions used in this work show that the outer tube side heat transfer coefficients are smaller than the inner side heat transfer coefficients by a factor of almost 1.5 and 3.4 in counter flow and parallel flow arrangements, respectively. The agreement with predictions is very good for the counter flow arrangement, but not very good for the parallel flow arrangement

  8. STUDY OF THE INFLUENCE OF THE HEAT INPUT ON MECHANICAL PROPERTIES OF C-Mn STEEL WELD METALS OBTAINED BY SUBMERGED ARC PROCESS

    Directory of Open Access Journals (Sweden)

    Erick de Sousa Marouço

    2013-06-01

    Full Text Available The present work is part of a research program that aims to evaluate the technical feasibility of increasing productivity in the manufacturing of tubular components for offshore oil industry, which are fully welded by automatic submerged arc welding process, with high heat input, but with no impairment on the impact toughness of the weld metal. Multipass welds were produced by the submerged arc welding process, with a combination of F7A4-EM12K (wire/flux, by using a 3.2 mm-diameter wire, preheating at 80°C, with direct current, in flat position, with heat input varying from 3.5 kJ/mm to 12 kJ/mm. After welding, tensile tests and Charpy-V impact tests at –60°C, –40°C, –20°C, 0°C and 20°C were carried out, as well as metallographic examination by both optical (OM and scanning electron microscopy (SEM, of specimens obtained entirely from the weld metal, allowing the discussion over the toughness X microstructure relationship. The weld metals have shown higher toughness levels in relation to the minimum required for use with low-alloy C-Mn steels welding with requirements of impact toughness of 27 J at 0°C for heat input up to 12 kJ/mm allowing an increase in productivity of 58% on the effective manufacturing time.

  9. Operation characteristic of a heat pump of mechanical vapor recompression propelled by fans and its performance analysis applied to waste-water treatment

    Science.gov (United States)

    Weike, Pang; Wenju, Lin; Qilin, Pan; Wenye, Lin; Qunte, Dai; Luwei, Yang; Zhentao, Zhang

    2014-01-01

    In this paper, a set of heat pump (called as Mechanical Vapor Recompression, MVR) propelled by a centrifugal fan is tested and it shows some special characteristic when it works together with a falling film evaporator. Firstly, an analysis of the fan's suction and discharge parameters at stable state, such as its pressure and temperature, indicates that a phenomenon of wet compression is probably to appear during vapor compression. As a result, superheat after saturated vapor is compressed is eliminated, which reduces discharge temperature of the system. It is because drops boil away and absorb the super heat into their latent heat during vapor compression. Meanwhile, drops in the suction vapor add to the compressed vapor, which increase the given heat of the MVR heat pump. Next, assistant electric heat could adjust and keep steady of the operating pressure and temperature of an MVR heat pump. With the evaporation temperature up to be high, heat balance is broken and supplement heat needs to increase. Thirdly, the performance of an MVR heat pump is affect by the balance of falling film and evaporation that has an effect on heat transfer. Then, two parameters standing for the performance are measured as it runs in practical condition. The two important parameters are consumptive electricity power and productive water capacity. According to theoretical work in ideal condition by calculation and fan's input power by measure as running, adiabatic efficiency (ηad) of a centrifugal fan is calculated when it is applied in a heat pump of MVR. Following, based on ηad, practical SMER and COP of an MVR heat pump are discovered to be correlative with it. Finally, in dependence on productive water in theory and in practice, displacement efficiency (ηv) of centrifugal fans is obtained when compressing vapor, and so provide some references of matching a fan for an MVR heat pump. On the other hand, it is helpful to research and develop MVR heat pumps, and also to check

  10. Investigation on the heat transfer characteristics during flow boiling of liquefied natural gas in a vertical micro-fin tube

    Science.gov (United States)

    Xu, Bin; Shi, Yumei; Chen, Dongsheng

    2014-03-01

    This paper presents an experimental investigation on the heat transfer characteristics of liquefied natural gas flow boiling in a vertical micro-fin tube. The effect of heat flux, mass flux and inlet pressure on the flow boiling heat transfer coefficients was analyzed. The Kim, Koyama, and two kinds of Wellsandt correlations with different Ftp coefficients were used to predict the flow boiling heat transfer coefficients. The predicted results showed that the Koyama correlation was the most accurate over the range of experimental conditions.

  11. Heat transfer and pressure drop characteristics of the tube bank fin heat exchanger with fin punched with flow redistributors and curved triangular vortex generators

    Science.gov (United States)

    Liu, Song; Jin, Hua; Song, KeWei; Wang, LiangChen; Wu, Xiang; Wang, LiangBi

    2017-10-01

    The heat transfer performance of the tube bank fin heat exchanger is limited by the air-side thermal resistance. Thus, enhancing the air-side heat transfer is an effective method to improve the performance of the heat exchanger. A new fin pattern with flow redistributors and curved triangular vortex generators is experimentally studied in this paper. The effects of the flow redistributors located in front of the tube stagnation point and the curved vortex generators located around the tube on the characteristics of heat transfer and pressure drop are discussed in detail. A performance comparison is also carried out between the fins with and without flow redistributors. The experimental results show that the flow redistributors stamped out from the fin in front of the tube stagnation points can decrease the friction factor at the cost of decreasing the heat transfer performance. Whether the combination of the flow redistributors and the curved vortex generators will present a better heat transfer performance depends on the size of the curved vortex generators. As for the studied two sizes of vortex generators, the heat transfer performance is promoted by the flow redistributors for the fin with larger size of vortex generators and the performance is suppressed by the flow redistributors for the fin with smaller vortex generators.

  12. A Study on Field Emission Characteristics of Planar Graphene Layers Obtained from a Highly Oriented Pyrolyzed Graphite Block.

    KAUST Repository

    Lee, Seok Woo; Lee, Seung S; Yang, Eui-Hyeok

    2009-01-01

    This paper describes an experimental study on field emission characteristics of individual graphene layers for vacuum nanoelectronics. Graphene layers were prepared by mechanical exfoliation from a highly oriented pyrolyzed graphite block and placed on an insulating substrate, with the resulting field emission behavior investigated using a nanomanipulator operating inside a scanning electron microscope. A pair of tungsten tips controlled by the nanomanipulator enabled electric connection with the graphene layers without postfabrication. The maximum emitted current from the graphene layers was 170 nA and the turn-on voltage was 12.1 V.

  13. A Study on Field Emission Characteristics of Planar Graphene Layers Obtained from a Highly Oriented Pyrolyzed Graphite Block.

    KAUST Repository

    Lee, Seok Woo

    2009-07-12

    This paper describes an experimental study on field emission characteristics of individual graphene layers for vacuum nanoelectronics. Graphene layers were prepared by mechanical exfoliation from a highly oriented pyrolyzed graphite block and placed on an insulating substrate, with the resulting field emission behavior investigated using a nanomanipulator operating inside a scanning electron microscope. A pair of tungsten tips controlled by the nanomanipulator enabled electric connection with the graphene layers without postfabrication. The maximum emitted current from the graphene layers was 170 nA and the turn-on voltage was 12.1 V.

  14. Characteristics of time-activity curves obtained from dynamic 11C-methionine PET in common primary brain tumors.

    Science.gov (United States)

    Nomura, Yuichi; Asano, Yoshitaka; Shinoda, Jun; Yano, Hirohito; Ikegame, Yuka; Kawasaki, Tomohiro; Nakayama, Noriyuki; Maruyama, Takashi; Muragaki, Yoshihiro; Iwama, Toru

    2018-07-01

    The aim of this study was to assess whether dynamic PET with 11 C-methionine (MET) (MET-PET) is useful in the diagnosis of brain tumors. One hundred sixty patients with brain tumors (139 gliomas, 9 meningiomas, 4 hemangioblastomas and 8 primary central nervous system lymphomas [PCNSL]) underwent dynamic MET-PET with a 3-dimensional acquisition mode, and the maximum tumor MET-standardized uptake value (MET-SUV) was measured consecutively to construct a time-activity curve (TAC). Furthermore, receiver operating characteristic (ROC) curves were generated from the time-to-peak (TTP) and the slope of the curve in the late phase (SLOPE). The TAC patterns of MET-SUVs (MET-TACs) could be divided into four characteristic types when MET dynamics were analyzed by dividing the MET-TAC into three phases. MET-SUVs were significantly higher in early and late phases in glioblastoma compared to anaplastic astrocytoma, diffuse astrocytoma and the normal frontal cortex (P dynamic MET-PET study could be helpful in the non-invasive discrimination of brain tumor subtypes, in particular gliomas.

  15. Process and device for determining the effect of river water heating by waste heat on its temperature characteristics

    International Nuclear Information System (INIS)

    Pietzsch, L.; Kauer, H.; Lautersack, K.

    1979-01-01

    It is proposed to use measurements for determining the effect of heating river water by introducing waste heat from industrial plants or power-stations, instead of deriving the effect from calculations. A suitable method of measurement is proposed and discussed. (UWI) 891 HP/UWI 892 CKA [de

  16. Flow boiling heat transfer and pressure drop characteristics of R134a, R1234yf and R1234ze in a plate heat exchanger for organic Rankine cycle units

    DEFF Research Database (Denmark)

    Zhang, Ji; Desideri, Adriano; Kærn, Martin Ryhl

    2017-01-01

    . This paper is aimed at obtaining flow boiling heat transfer and pressure drop characteristics in a plate heat exchanger under the working conditions prevailing in the evaporator of organic Rankine cycle units. Two hydrofluoroolefins R1234yf and R1234ze, and one hydrofluorocarbon R134a, were selected...... as the working fluids. The heat transfer coefficients and pressure drops of the three working fluids were measured with varying saturation temperatures, mass fluxes, heat fluxes and outlet vapour qualities, which range from 60°C to 80°C, 86 kg/m2 s to 137 kg/m2 s, 9.8 kW/m2 to 36.8 kW/m2 and 0.5 to 1...... developed that are more suitable for evaporation in organic Rankine cycles. The experimental results indicate that heat transfer coefficients are strongly dependent upon the heat flux and saturation temperature. Moreover, the results suggest better thermal-hydraulic performance for R1234yf than the other...

  17. Study of microstructure and superconducting properties of Nb3Al-tapes, obtained by heat treatment of three-layer and multilayer composites Nb/AlCu

    International Nuclear Information System (INIS)

    Korzhov, Valeriy P.

    2012-01-01

    The structure and superconductivity of three- and multilayer composite tapes of Nb/AlCu after high- temperature heating at 1750-1850 0 C for 1-3 seconds were investigated. Three-layer composites of Nb/AlCu/Nb with thickness of 50 microns were obtained by applying a vacuum rolling at 400-450 0 C and subsequent rolling at room temperature. Multilayer lengthy composites of Nb/AlCu obtained by extrusion with subsequent flattening by rolling of complex blank, collected in a special way. The effect of copper on the structure and properties of three-layer tapes was investigated. Copper increased the critical current of the superconductor. The critical current density in multilayered Nb 3 Al-tape reaches the value 8.10 4 A/cm 2 in magnetic field 14 T. The critical bending radius of the tape is 7 mm. Key words: multilayer composite tape, extrusion, rolling, superconducting Nb 3 Al-tape, high- temperature heat treatment, critical current density

  18. Extracts Obtained from Pterocarpus angolensis DC and Ziziphus mucronata Exhibit Antiplasmodial Activity and Inhibit Heat Shock Protein 70 (Hsp70 Function

    Directory of Open Access Journals (Sweden)

    Tawanda Zininga

    2017-07-01

    Full Text Available Malaria parasites are increasingly becoming resistant to currently used antimalarial therapies, therefore there is an urgent need to expand the arsenal of alternative antimalarial drugs. In addition, it is also important to identify novel antimalarial drug targets. In the current study, extracts of two plants, Pterocarpus angolensis and Ziziphus mucronata were obtained and their antimalarial functions were investigated. Furthermore, we explored the capability of the extracts to inhibit Plasmodium falciparum heat shock protein 70 (Hsp70 function. Heat shock protein 70 (Hsp70 are molecular chaperones whose function is to facilitate protein folding. Plasmodium falciparum the main agent of malaria, expresses two cytosol-localized Hsp70s: PfHsp70-1 and PfHsp70-z. The PfHsp70-z has been reported to be essential for parasite survival, while inhibition of PfHsp70-1 function leads to parasite death. Hence both PfHsp70-1 and PfHsp70-z are potential antimalarial drug targets. Extracts of P. angolensis and Z. mucronata inhibited the basal ATPase and chaperone functions of the two parasite Hsp70s. Furthermore, fractions of P. angolensis and Z. mucronata inhibited P. falciparum 3D7 parasite growth in vitro. The extracts obtained in the current study exhibited antiplasmodial activity as they killed P. falciparum parasites maintained in vitro. In addition, the findings further suggest that some of the compounds in P. angolensis and Z. mucronata may target parasite Hsp70 function.

  19. Approach to the surface characteristics of the H+ and H+-La3+ forms of cation-exchange resins by measurement of the heat of immersion

    International Nuclear Information System (INIS)

    Suzuki, T.; Uematsu, T.

    1985-01-01

    Surface characteristics of H + and its multivalent cation-exchanged resins, which have been used as catalysts, were probed by measurement of the heats of immersion in 1-nitropropane, n-hexane, and water. It was found that the electrostatic field strengths (F) calculated from the heats of immersion in 1-nitropropane and n-hexane increased with increasing ratios of the exchanged multivalent cation (La 3+ ) in the univalent form (H + ) cation-exchange resin. This tendency was also observed in the differences in F between the La 3+ exchanged resins and H + form of the resin by using the calorimetric data obtained from the heats of immersion in water. These results suggest that the exchanged La 3 μ ion does not homogeneously interact with three univalent anionic sites (SO 3 - ) of the cation-exchange resin, but interacts with only two SO 3 - ions, that is, the La 3+ ion is localized on the surface of the resin. The difference in F obtained from the heats of immersion into water was found to be useful as a simple and rapid criterion of the surface characteristics of the cation-exchange resins. 18 references, 4 figures, 1 table

  20. Numerical assessment and comparison of heat transfer characteristics of supercritical water in bare tubes and tubes with heat transfer enhancing appendages

    International Nuclear Information System (INIS)

    Farah, Amjad; Harvel, Glenn; Pioro, Igor

    2015-01-01

    Computational Fluid Dynamics (CFD) is a numerical approach to model fluids in multidimensional space using the Navier-Stokes equations and databases of fluid properties to arrive at a full simulation of a fluid dynamics and heat transfer system. A numerical study on heat transfer to supercritical water (SCW) flowing in a vertical tube is carried out using the ANSYS FLUENT code and employing the SST k-ω turbulence model. The 3D mesh consists of a 1/8 section (45deg radially) of a bare tube. The numerical results on wall temperature distributions under normal and deteriorated heat transfer conditions are compared to experimental results. The same geometry is then simulated with an orifice to study the effect of geometrical perturbation on the flow and heat transfer characteristics of SCW. The orifice is placed areas to test the effect on normal, deteriorated and enhanced heat transfer regimes. The flow effects and heat transfer characteristics will be studied around the appendages to arrive at a fundamental understanding of the phenomena related to supercritical water turbulence. (author)

  1. Experimental research on single-phase heat transfer characteristics in a vertical circular tube under marine conditions

    International Nuclear Information System (INIS)

    Du Sijia; Zhang Hong; Jia Baoshan

    2011-01-01

    Experiments have been conducted to study the heat transfer characteristics of single-phase forced circulation when the test tube was under different marine conditions. The experiments measured the wall temperature of test tube to calculate the heat transfer coefficients at different circumferential places. When the test tube was under inclined conditions, the heat transfer coefficient increased at downside and decreased at upside of test tube because of buoyancy effect. When the test tube was under rolling conditions, the heat transfer coefficients fluctuated with the rolling motions, and the Coriolis force dominated the heat transfer fluctuation during the rolling motion. CFD method was used to simulate the heat transfer phenomena under marine conditions, and the results were accord to the experimental phenomena. (authors)

  2. Heat transfer characteristics and entropy generation for wing-shaped-tubes with longitudinal external fins in cross-flow

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Sayed Ahmed E. Sayed; Mesalhy, Osama M.; Abdelatief, Mohamed A. [Zagazig University, Zagazig (Egypt)

    2016-06-15

    A numerical study is conducted to clarify heat transfer characteristics, effectiveness and entropy generation for a bundle of wingshaped-tubes attached to Longitudinal fins (LF) at downstream side. The air-side Re{sub a} ranged from 1.8 x 10{sup 3} to 9.7 x 10{sup 3} . The fin height (h{sub f}) and fin thickness (δ) have been changed as: (2 mm <= hf <= 12 mm) and (1.5 mm <= δ <= 3.5 mm). The analysis of entropy generation is based on the principle of minimizing the rate of total entropy generation that includes the generation of entropy due to heat transfer and friction losses. The temperature field around the wing-shaped-tubes with (LF) is predicted using commercial CFD FLUENT 6.3.26 software package. Correlations of Nu{sub a}, St{sub a}, and Bejan number (Be), as well as the irreversibility distribution ratio (Φ) in terms of Re{sub a} and design parameters for the studied bundle are presented. Results indicated that, installing fins with heights from 2 to 12 mm results in an increase in Nu{sub a} from 11 to 36% comparing with that of wing-shaped tubes without fins (NOF). The highest and lowest values of effectiveness(ε) at every value of the considered Re{sub a} range are occurred at hf = 6 mm and (NOF), espectively. The wing-shaped-tubes heat exchanger with hf = 6 mm has the highest values of (ε), efficiency index (η) and area goodness factor (G{sub a}) and also the lowest values of Φ and hence the best performance comparing with other arrangements. The minimum values of Φ are occurred at hf = 6 mm. (Be) decreases with increasing Re{sub a} for all studied hf. The heat transfer irreversibility predominates for (1800 <= Re{sub a} <= 4200) while the opposite is true for (6950 < Re{sub a} <= 9700). δ has negligible effect on Nu{sub a} and heat transfer irreversibility. Comparisons between the experimental and numerical results of the present study and those, previously, obtained for similar available studies showed good agreements.

  3. Heat transfer characteristics and entropy generation for wing-shaped-tubes with longitudinal external fins in cross-flow

    International Nuclear Information System (INIS)

    Ahmed, Sayed Ahmed E. Sayed; Mesalhy, Osama M.; Abdelatief, Mohamed A.

    2016-01-01

    A numerical study is conducted to clarify heat transfer characteristics, effectiveness and entropy generation for a bundle of wingshaped-tubes attached to Longitudinal fins (LF) at downstream side. The air-side Re a ranged from 1.8 x 10 3 to 9.7 x 10 3 . The fin height (h f ) and fin thickness (δ) have been changed as: (2 mm <= hf <= 12 mm) and (1.5 mm <= δ <= 3.5 mm). The analysis of entropy generation is based on the principle of minimizing the rate of total entropy generation that includes the generation of entropy due to heat transfer and friction losses. The temperature field around the wing-shaped-tubes with (LF) is predicted using commercial CFD FLUENT 6.3.26 software package. Correlations of Nu a , St a , and Bejan number (Be), as well as the irreversibility distribution ratio (Φ) in terms of Re a and design parameters for the studied bundle are presented. Results indicated that, installing fins with heights from 2 to 12 mm results in an increase in Nu a from 11 to 36% comparing with that of wing-shaped tubes without fins (NOF). The highest and lowest values of effectiveness(ε) at every value of the considered Re a range are occurred at hf = 6 mm and (NOF), espectively. The wing-shaped-tubes heat exchanger with hf = 6 mm has the highest values of (ε), efficiency index (η) and area goodness factor (G a ) and also the lowest values of Φ and hence the best performance comparing with other arrangements. The minimum values of Φ are occurred at hf = 6 mm. (Be) decreases with increasing Re a for all studied hf. The heat transfer irreversibility predominates for (1800 <= Re a <= 4200) while the opposite is true for (6950 < Re a <= 9700). δ has negligible effect on Nu a and heat transfer irreversibility. Comparisons between the experimental and numerical results of the present study and those, previously, obtained for similar available studies showed good agreements.

  4. First in-core simultaneous measurements of nuclear heating and thermal neutron flux obtained with the innovative mobile calorimeter CALMOS inside the OSIRIS reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lepeltier, Valerie; Bubendorff, Jacques; Carcreff, Hubert [Nuclear studies and reactor irradiation Service, CEA Saclay 91191 Gif sur Yvette (France); Salmon, Laurent [Thermalhydraulics and Fluid Mechanics Section, CEA Saclay 91191 Gif sur Yvette, (France)

    2015-07-01

    Nuclear heating inside a MTR reactor has to be known in order to design and to run irradiation experiments which have to fulfill target temperature constraints. This measurement is usually carried out by calorimetry. The innovative calorimetric system, CALMOS, has been studied and built in 2011 for the 70 MWth OSIRIS reactor operated by CEA. Thanks to a new type of calorimetric probe, associated to a specific displacement system, it provides measurements along the fissile height and above the core. This development required preliminary modelling and irradiation of mock-ups of the calorimetric probe in the ex-core area, where nuclear heating rate does not exceed 2 W.g{sup -1}. The calorimeter working modes, the different measurement procedures allowed with such a new probe, the main modeling and experimental results and expected advantages of this new technique have been already presented. However, these first in-core measurements were not performed beyond 6 W.g{sup -1}, due to an inside temperature limitation imposed by a safety authority requirement. In this paper, we present the first in-core simultaneous measurements of nuclear heating and conventional thermal neutron flux obtained by the CALMOS device at the 70 MW nominal reactor power. For the first time, this experimental system was operated in nominal in-core conditions, with nominal neutron flux up to 2.7 10{sup 14} n.cm{sup -2}.s{sup -1} and nuclear heating up to 12 W.g{sup -1}. A comprehensive measurement campaign carried out from 2013 to 2015 inside all accessible irradiation locations of the core, allowed to qualify definitively this new device, not only in terms of measurement ability but also in terms of reliability. After a brief reminder of the calorimetric cell configuration and displacement system specificities, first nuclear heating distributions at nominal power are presented and discussed. In order to reinforce the heating evaluation, a systematic comparison is made between results obtained by

  5. Full-scale prototyping of the Hitachi dual-purpose metal cask and verification of its heat transfer characteristics

    International Nuclear Information System (INIS)

    Kumagai, N.; Ishida, N.; Ootsuka, M.; Kamoshida, M.; Hiranuma, T.; Doumori, S.; Hoshikawa, T.; Shimizu, M.; Kashiwakura, J.; Hayashi, M.

    2004-01-01

    Hitachi has been developing dual-purpose metal casks for transport and storage of spent nuclear fuels. The Hitachi cask, HDP69B can store 69 BWR fuel assemblies. The cask features are as follows. 1) The fuel basket is assembled mainly with plates of borated stainless steel. The plates are not welded, but cross-inserted into each other like the dividers in an egg carton. Since the borated stainless steel has relatively low heat conductivity, aluminum alloy plates are inserted along with some stainless steel plates to enhance heat removal ability. 2) Cured resin blocks are fitted into the inner shell of the cask for neutron shielding of the cask body. The resin blocks are surrounded by an aluminum casing which transfers heat of stored fuel from the inner shell to the outer shell of the cask. The block type shield structure eliminates the need for welding the heat transfer fins to the inner and outer shells. The weldless structures of the HDP69B lead to its enhanced manufacturability, but they complicate the heat transfer characteristics because there are gaps between such components as the aluminum casing and inner/outer shells. We carried out full-scale prototyping of the HDP69B and ran a heat transfer test using the prototype. The purposes of the heat transfer test were to check the heat removal ability of the HDP69B and to verify the safety analysis model for heat removal. Results of the heat transfer test and optimized analysis model for heat transfer characteristics of the HDP69B are the focus of this paper. The heat transfer test is summarized as follows. Sixty nine heaters simulating the shape and heat power of spent fuel assemblies were inserted into the fuel basket. After replacing the inner atmosphere with 0.1 MPa of helium, the heat transfer test was started. About 7 days were required to equilibrate the temperature distribution. The temperature at the center of the basket was 194 C. The results confirmed the HDP69B had sufficient heat removal ability. The

  6. Numerical investigation of heat transfer and friction factor characteristics in a circular tube fitted with V-cut twisted tape inserts.

    Science.gov (United States)

    Salman, Sami D; Kadhum, Abdul Amir H; Takriff, Mohd S; Mohamad, Abu Bakar

    2013-01-01

    Numerical investigation of the heat transfer and friction factor characteristics of a circular fitted with V-cut twisted tape (VCT) insert with twist ratio (y = 2.93) and different cut depths (w = 0.5, 1, and 1.5 cm) were studied for laminar flow using CFD package (FLUENT-6.3.26). The data obtained from plain tube were verified with the literature correlation to ensure the validation of simulation results. Classical twisted tape (CTT) with different twist ratios (y = 2.93, 3.91, 4.89) were also studied for comparison. The results show that the enhancement of heat transfer rate induced by the classical and V-cut twisted tape inserts increases with the Reynolds number and decreases with twist ratio. The results also revealed that the V-cut twisted tape with twist ratio y = 2.93 and cut depth w = 0.5 cm offered higher heat transfer rate with significant increases in friction factor than other tapes. In addition the results of V-cut twist tape compared with experimental and simulated data of right-left helical tape inserts (RLT), it is found that the V-cut twist tape offered better thermal contact between the surface and the fluid which ultimately leads to a high heat transfer coefficient. Consequently, 107% of maximum heat transfer was obtained by using this configuration.

  7. Influence of heat treated microstructures on the dynamic deformation characteristics of Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Seo, Yong Seok; Lee, Yong Shin; Woo, Sung Choong; Kim, Tae Won

    2015-01-01

    We investigated the influence of heat treated microstructures, namely, equiaxed, bimodal and lamella types of Ti-6Al-4V alloy on the dynamic deformation characteristics. Four different heat treatment conditions were employed for the development of the microstructures. Static tensile and compressive deformation tests were preliminarily performed with hydraulic test equipment. Dynamic deformation tests at a high level of strain rate, 2700 s"-"1 ∼ 6400 s"-"1, together with high velocity impact tests were, respectively, conducted on the specimens through a compressive Split Hopkinson pressure bar (SHPB) and a high pressure gas gun system. The dependence of flow stress on the strain rate associated with the corresponding microstructure was examined. The microstructural factors on the dynamic fracture characteristics were analyzed by scanning electron microscopy. The static compressive tests showed that the flow stress was greatest in the lamella microstructure and decreased in the order of lamella, bimodal and equiaxed microstructures, whereas the ductility was largest in the bimodal microstructure and smallest in the lamellar microstructure. In dynamic compressive tests, a similar dependency of the flow stress on microstructures was observed: highest in the lamellar microstructure and lowest in the equiaxed microstructure. The ductility, such as strain at maximum stress or at failure, was highest in the equiaxed microstructure and lowest in the lamellar structure. In addition, the ductility for individual microstructure decreased as the strain rate increased. Every microstructure exhibited ductile fracture surfaces, and it seems that a large shear crack on the lateral surface in the specimen was the main factor inducing the final failure. The result of high velocity impact test exhibited that the resistance to fracture of equiaxed microstructure with superior dynamic toughness was much higher than that of lamella microstructure with inferior dynamic toughness. The

  8. Influence of heat treated microstructures on the dynamic deformation characteristics of Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Yong Seok; Lee, Yong Shin [Chungnam National University, Daejeon (Korea, Republic of); Woo, Sung Choong; Kim, Tae Won [Hanyang University, Seoul (Korea, Republic of)

    2015-11-15

    We investigated the influence of heat treated microstructures, namely, equiaxed, bimodal and lamella types of Ti-6Al-4V alloy on the dynamic deformation characteristics. Four different heat treatment conditions were employed for the development of the microstructures. Static tensile and compressive deformation tests were preliminarily performed with hydraulic test equipment. Dynamic deformation tests at a high level of strain rate, 2700 s{sup -1} ∼ 6400 s{sup -1}, together with high velocity impact tests were, respectively, conducted on the specimens through a compressive Split Hopkinson pressure bar (SHPB) and a high pressure gas gun system. The dependence of flow stress on the strain rate associated with the corresponding microstructure was examined. The microstructural factors on the dynamic fracture characteristics were analyzed by scanning electron microscopy. The static compressive tests showed that the flow stress was greatest in the lamella microstructure and decreased in the order of lamella, bimodal and equiaxed microstructures, whereas the ductility was largest in the bimodal microstructure and smallest in the lamellar microstructure. In dynamic compressive tests, a similar dependency of the flow stress on microstructures was observed: highest in the lamellar microstructure and lowest in the equiaxed microstructure. The ductility, such as strain at maximum stress or at failure, was highest in the equiaxed microstructure and lowest in the lamellar structure. In addition, the ductility for individual microstructure decreased as the strain rate increased. Every microstructure exhibited ductile fracture surfaces, and it seems that a large shear crack on the lateral surface in the specimen was the main factor inducing the final failure. The result of high velocity impact test exhibited that the resistance to fracture of equiaxed microstructure with superior dynamic toughness was much higher than that of lamella microstructure with inferior dynamic toughness

  9. Time and temperature dependent breakdown characteristics of ZnS:Mn films obtained by rf-magnetron sputtering

    Science.gov (United States)

    Zhigal'Skii, A. A.; Mukhachev, V. A.; Troyan, P. E.

    1994-04-01

    Breakdown delay times (tdel) for films of managanese-doped zinc sulfide (ZnS:Mn) were measured in the range 10-6-10-1 s. The maximum value was tdel=10-3-10-2 s. The electrical strength (Ebr) was found to increase as the voltage pulse duration was reduced, the more so the thinner the ZnS:Mn film. The temperature dependence of Ebr exhibited a weak reduction in Ebr as the temperature was raised to roughly 80°C and a sharp reduction in Ebr for T>130°C. A maximum in Ebr was observed at T≈130°C which is presumably explained by a structural modification of the ZnS:Mn film. The experimental results obtained are explained in terms of a combined electronic and thermal breakdown mechanism.

  10. Chemical, structural and combustion characteristics of carbonaceous products obtained by hydrothermal carbonization of palm empty fruit bunches.

    Science.gov (United States)

    Parshetti, Ganesh K; Kent Hoekman, S; Balasubramanian, Rajasekhar

    2013-05-01

    A carbon-rich solid product, denoted as hydrochar, was synthesized by hydrothermal carbonization (HTC) of palm oil empty fruit bunch (EFB), at different pre-treatment temperatures of 150, 250 and 350 °C. The conversion of the raw biomass to its hydrochar occurred via dehydration and decarboxylation processes. The hydrochar produced at 350 °C had the maximum energy-density (>27 MJ kg(-1)) with 68.52% of raw EFB energy retained in the char. To gain a detailed insight into the chemical and structural properties, carbonaceous hydrochar materials were characterized by FE-SEM, FT-IR, XRD and Brunauer-Emmett-Teller (BET) analyses. This work also investigated the influence of hydrothermally treated hydrochars on the co-combustion characteristics of low rank Indonesian coal. Conventional thermal gravimetric analysis (TGA) parameters, kinetics and activation energy of different hydrochar and coal blends were estimated. Our results show that solid hydrochars improve the combustion of low rank coals for energy generation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Marked heterogeneity in growth characteristics of myoblast clonal cultures and myoblast mixed cultures obtained from the same individual.

    Science.gov (United States)

    Maier, Andrea B; Cohen, Ron; Blom, Joke; van Heemst, Diana; Westendorp, Rudi G J

    2012-01-01

    Sarcopenia is defined as an age-related decrease in skeletal muscle mass and function while adjacent satellite cells are unable to compensate for this loss. However, myoblast cultures can be established even in the presence of sarcopenia. It is yet unknown whether satellite cells from failing muscle in older age are equally affected, as human satellite cells have been assessed using myoblast mixed cultures and not by using myoblast clonal cultures. We questioned to what extent myoblast mixed cultures reflect the in vivo characteristics of single satellite cells from adult skeletal muscle. We established a myoblast mixed culture and three myoblast clonal cultures out of the same muscle biopsy and cultured these cells for 100 days. Replicative capacity and oxidative stress resistance were compared. We found marked heterogeneity between the myoblast clonal cultures that all had a significantly lower replicative capacity when compared to the mixed culture. Replicative capacity of the clonal cultures was inversely related to the β-galactosidase activity after exposure to oxidative stress. Addition of L-carnosine enhanced the remaining replicative capacity in all cultures with a concomitant marginal decrease in β-galactosidase activity. It is concluded that myoblast mixed cultures in vitro do not reflect the marked heterogeneity between single isolated satellite cells. The consequences of the heterogeneity on muscle performance remain to be established. Copyright © 2011 S. Karger AG, Basel.

  12. Vial freeze-drying, part 1: new insights into heat transfer characteristics of tubing and molded vials.

    Science.gov (United States)

    Hibler, Susanne; Wagner, Christophe; Gieseler, Henning

    2012-03-01

    In order to optimize a freeze-drying cycle, information regarding the heat transfer characteristics of the container system is imperative. Two most recently developed tubing (TopLyo™) and molded (EasyLyo™) vial designs were compared with a standard serum tubing and molded vial, a polymer vial (TopPac™), and an amber molded EasyLyo™. In addition, the impact of methodology on the determination of reliable vial heat transfer coefficient (K(v) ) data is examined in detail. All K(v) s were gravimetrically determined by sublimation tests with pure water at 50, 100, 200, and 400 mTorr. In contrast to the traditional assumption that molded vials exhibit inefficient heat transfer characteristics, these vials showed a very similar performance compared with their serum tubing counterparts in the relevant pressure range for freeze-drying. At 100 mTorr, the TopLyo™ center vials show only 4% higher K(v) values than the EasyLyo™ center vials. All glass vials outmatch the polymer vial in terms of heat transfer, up to 30% elevated heat transfer for the TopLyo™ center vials at 400 mTorr. Sublimation tests have demonstrated to be a valuable tool to investigate the heat transfer characteristics of vials, but results are dependent on methodology. New developments in molded vial manufacturing lead to improved heat transfer performance. Copyright © 2011 Wiley Periodicals, Inc.

  13. [Characteristics of water and heat fluxes and its footprint climatology on farmland in low hilly region of red soil].

    Science.gov (United States)

    Li, Yang; Jing, Yuan Shu; Qin, Ben Ben

    2017-01-01

    The analysis of the characteristics and footprint climatology of farmland water and heat fluxes has great significance to strengthen regional climate resource management and improve the hydrothermal resource utilization in the region of red soil. Based on quality controlled data from large aperture scintillometer and automatic meteorological station in hilly region of red soil, this paper analyzed in detail the characteristics of farmland water and heat fluxes at different temporal scales and the corresponding source area distribution of flux measurement in the non-rainy season and crop growth period in hilly region of red soil. The results showed that the diurnal variation of water and heat fluxes showed a unimodal trend, but compared with the sunny day, the diurnal variation curves fluctuated more complicatedly on cloudy day. In the whole, either ten-day periods or month scale, the water and heat fluxes were greater in August than in September, while the net radiation flux was more distributed to latent heat exchange. The proportion of net radiation to latent heat flux decreased in September compared to August, but the sensible heat flux was vice versa. With combined effects of weather conditions (particularly wind), stability, and surface condition, the source areas of flux measurement at different temporal scales showed different distribution characteristics. Combined with the underlying surface crops, the source areas at different temporal scales also had different contribution sources.

  14. Transient heat characteristics of water-saturated porous media with freezing; Toketsu wo tomonau gansui takoshitsu sonai no hiteijo netsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, A [Akita National College of Technology, Akita (Japan)

    1998-02-25

    Analytical and experimental investigations were performed to examine the transient heat characteristics of water-saturated porous media with freezing. As a physical model, a two-dimensional vertical cavity was considered. One vertical wall was abruptly cooled below the fusion temperature. Other three walls were thermally insulated. Three different sizes of glass, and iron, alumina and copper beads were used as the porous media in this study. The cold energy stored up in the porous media and the average thickness of frozen layer were measured in the experiments. Comparisons of the analytical results with the experimental ones were made, and the effects of Darcy number, Stefan number and modified Prandtl number on the transient heat characteristics were discussed. The dimensionless equations for predicting the averaged frozen layer thickness and the stored cold energy were obtained as a function of various dimensionless parameters. 8 refs., 16 figs., 1 tab.

  15. Critical heat flux and transition boiling characteristics for a sodium-heated steam generator tube for LMFBR applications

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, S.; Holmes, D.H.

    1977-04-01

    An experimental program was conducted to characterize critical heat flux (CHF) in a sodium-heated steam generator tube model at a proposed PLBR steam generator design pressure of 7.2 MPa. Water was circulated vertically upward in the tube and the heating sodium was flowing counter-current downward. The experimental ranges were: mass flux, 110 to 1490 kg/s.m/sup 2/ (0.08 to 1.10 10/sup 6/ lbm/h.ft/sup 2/); critical heat flux, 0.16 to 1.86 MW/m/sup 2/ (0.05 to 0.59 10/sup 6/ Btu/h.ft/sup 2/); and critical quality, 0.48 to 1.0. The CHF phenomenon for the experimental conditions is determined to be dryout as opposed to departure from nucleate boiling (DNB). The data are divided into high- and low-mass flux regions.

  16. Heat flux characteristics of spray wall impingement with ethanol, butanol, iso-octane, gasoline and E10 fuels

    International Nuclear Information System (INIS)

    Serras-Pereira, J.; Aleiferis, P.G.; Walmsley, H.L.; Davies, T.J.; Cracknell, R.F.

    2013-01-01

    Highlights: • Heat flux sensors used to characterise the locations of fuel spray wall impingement. • Droplet evaporation modelling used to study the effect of fuel properties. • Behaviour of ethanol and butanol distinctively different to hydrocarbons. -- Abstract: Future fuel stocks for spark-ignition engines are expected to include a significant portion of bio-derived components with quite different chemical and physical properties to those of liquid hydrocarbons. State-of-the-art high-pressure multi-hole injectors for latest design direct-injection spark-ignition engines offer some great benefits in terms of fuel atomisation, as well as flexibility in in-cylinder fuel targeting by selection of the exact number and angle of the nozzle’s holes. However, in order to maximise such benefits for future spark-ignition engines and minimise any deteriorating effects with regards to exhaust emissions, it is important to avoid liquid fuel impingement onto the cylinder walls and take into consideration various types of biofuels. This paper presents results from the use of heat flux sensors to characterise the locations and levels of liquid fuel impingement onto the engine’s liner walls when injected from a centrally located multi-hole injector with an asymmetric pattern of spray plumes. Ethanol, butanol, iso-octane, gasoline and a blend of 10% ethanol with 90% gasoline (E10) were tested and compared. The tests were performed in the cylinder of a direct-injection spark-ignition engine at static conditions (i.e. quiescent chamber at 1.0 bar) and motoring conditions (at full load with inlet plenum pressure of 1.0 bar) with different engine temperatures in order to decouple competing effects. The collected data were analysed to extract time-resolved signals, as well as mean and standard deviation levels of peak heat flux. The results were interpreted with reference to in-cylinder spray formation characteristics, as well as fuel evaporation rates obtained by modelling

  17. Reactor type choice and characteristics for a small nuclear heat and electricity co-generation plant

    International Nuclear Information System (INIS)

    Liu Kukui; Li Manchang; Tang Chuanbao

    1997-01-01

    In China heat supply consumes more than 70 percent of the primary energy resource, which makes for heavy traffic and transportation and produces a lot of polluting materials such as NO x , SO x and CO 2 because of use of the fossil fuel. The utilization of nuclear power into the heat and electricity co-generation plant contributes to the global environmental protection. The basic concept of the nuclear system is an integral type reactor with three circuits. The primary circuit equipment is enclosed in and linked up directly with reactor vessel. The third circuit produces steam for heat and electricity supply. This paper presents basic requirements, reactor type choice, design characteristics, economy for a nuclear co-generation plant and its future application. The choice of the main parameters and the main technological process is the key problem of the nuclear plant design. To make this paper clearer, take for example a double-reactor plant of 450 x 2MW thermal power. There are two sorts of main technological processes. One is a water-water-steam process. Another is water-steam-steam process. Compared the two sorts, the design which adopted the water-water-steam technological process has much more advantage. The system is simplified, the operation reliability is increased, the primary pressure reduces a lot, the temperature difference between the secondary and the third circuits becomes larger, so the size and capacity of the main components will be smaller, the scale and the cost of the building will be cut down. In this design, the secondary circuit pressure is the highest among that of the three circuits. So the primary circuit radioactivity can not leak into the third circuit in case of accidents. (author)

  18. 3-D Transient Heat Transfer Analysis of Slab Heating Characteristics in a Reheating Furnace in Hot Strip Mills

    OpenAIRE

    J. Y. Jang; Y. W. Lee; C. N. Lin; C. H. Wang

    2015-01-01

    The reheating furnace is used to reheat the steel slabs before the hot-rolling process. The supported system includes the stationary/moving beams, and the skid buttons which block some thermal radiation transmitted to the bottom of the slabs. Therefore, it is important to analyze the steel slab temperature distribution during the heating period. A three-dimensional mathematical transient heat transfer model for the prediction of temperature distribution within the slab ha...

  19. Characteristics of nonlocally-coupled transition of the heat transport in LHD

    International Nuclear Information System (INIS)

    Tamura, N.; Ida, K.; Tanaka, K.; Tokuzawa, T.; Itoh, K.; Shimozuma, T.; Kubo, S.; Tsuchiya, H.; Nagayama, Y.; Kawahata, K.; Sudo, S.; Yamada, H.; Inagaki, S.

    2010-01-01

    A comparison of characteristics between a nonlocal transport phenomenon and an electron internal transport barrier (ITB) in the Large Helical Device is performed with a transient transport analysis and from the viewpoint of a dynamic behavior of transport state. The electron ITB is characterized by a jump of electron temperature gradient. In contrast, the transient transport analysis indicates the nonlocal transport phenomenon is characterized by a jump of electron heat flux. And seen from the viewpoint of the dynamic behavior of transport state, the physical mechanism of the appearance of the nonlocal transport phenomenon is found to be qualitatively different from that of the formation of the electron ITB. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Radionuclide Data Centre. Tasks and problems of obtaining the most reliable values of the nuclear physics characteristics of radionuclides and radiation physics parameters of radionuclide sources

    International Nuclear Information System (INIS)

    Chechev, V.P.

    1994-01-01

    Information is provided on the establishment of the Radionuclide Data Centre under the V.G. Khlopin Radium Institute. Its functions and areas of activity are discussed. The paper focuses on the procedure of obtaining the evaluated values of the decay and radiative characteristics of the widely used radionuclides. (author)

  1. Assessment of radio frequency heating on composition, microstructure, flowability and rehydration characteristics of milk powder

    Directory of Open Access Journals (Sweden)

    Yu ZHONG

    2017-10-01

    Full Text Available Abstract Radio frequency heating (RFH provides higher efficiency and more uniform heating zone compared with conventional method. The aim of present work is to evaluate the effect of RFH (at 90 °C for 5 or 10 min on the changes in composition (protein oxidation and fat distribution, microstructure, flow characteristic and rehydration property of infant milk powder. The results indicate that the concentration of protein dityrosine was slightly enhanced, more free fat appeared on powder surfaces (> 50% increase, and porosity in powder matrix as tested by SEM was increased after RFH treatment. For powder flowability, raw sample had low cohesiveness (specific energy = 4.39 mJ/g, and RFH provided better flowability and decreased compressibility. Moreover, RFH had some negative impacts on wettability and solubility of powder particles with contact angle increase at least 5% and solubility decrease of 2%~4%, indicating worse rehydration abilities. Guggenheim-Anderson-de Boer (GAB model was applied to fit moisture vapor sorption isotherms, and longer RFH duration leading to higher c values (about 63% increase at 10 min. In addition, the RFH initiated browning reaction as CIE a* values increased from -1.8 to -1.3.

  2. Characteristics of autoignited laminar lifted flames in heated coflow jets of carbon monoxide/hydrogen mixtures

    KAUST Repository

    Choi, Byungchul

    2012-06-01

    The characteristics of autoignited lifted flames in laminar jets of carbon monoxide/hydrogen fuels have been investigated experimentally in heated coflow air. In result, as the jet velocity increased, the blowoff was directly occurred from the nozzle-attached flame without experiencing a stabilized lifted flame, in the non-autoignited regime. In the autoignited regime, the autoignited lifted flame of carbon monoxide diluted by nitrogen was affected by the water vapor content in the compressed air oxidizer, as evidenced by the variation of the ignition delay time estimated by numerical calculation. In particular, in the autoignition regime at low temperatures with added hydrogen, the liftoff height of the autoignited lifted flames decreased and then increased as the jet velocity increased. Based on the mechanism in which the autoignited laminar lifted flame is stabilized by ignition delay time, the liftoff height can be influenced not only by the heat loss, but also by the preferential diffusion between momentum and mass diffusion in fuel jets during the autoignition process. © 2012 The Korean Society of Mechanical Engineers.

  3. An Experimental Investigation on the Combustion and Heat Release Characteristics of an Opposed-Piston Folded-Cranktrain Diesel Engine

    Directory of Open Access Journals (Sweden)

    Fukang Ma

    2015-06-01

    Full Text Available In opposed-piston folded-cranktrain diesel engines, the relative movement rules of opposed-pistons, combustion chamber components and injector position are different from those of conventional diesel engines. The combustion and heat release characteristics of an opposed-piston folded-cranktrain diesel engine under different operating conditions were investigated. Four phases: ignition delay, premixed combustion, diffusion combustion and after combustion are used to describe the heat release process of the engine. Load changing has a small effect on premixed combustion duration while it influences diffusion combustion duration significantly. The heat release process has more significant isochoric and isobaric combustion which differs from the conventional diesel engine situation, except at high exhaust pressure and temperature, due to its two-stroke and uniflow scavenging characteristics. Meanwhile, a relatively high-quality exhaust heat energy is produced in opposed-piston folded-cranktrain diesel engines.

  4. 3-D Transient Heat Transfer Analysis of Slab Heating Characteristics in a Reheating Furnace in Hot Strip Mills

    Science.gov (United States)

    Jang, J. Y.; Lee, Y. W.; Lin, C. N.; Wang, C. H.

    2016-05-01

    A three-dimensional mathematical transient heat transfer model for the prediction of temperature distribution within the slab has been developed by considering the thermal radiation in the walking-beam-type reheating furnace chamber. The steel slabs are heated up through the non-firing, preheating, 1st-heating, 2nd-heating, and soaking zones in the furnace, respectively, where the furnace wall temperature is function of time. Comparison with the in-situ experimental data from Steel Company in Taiwan shows that the present heat transfer model works well for the prediction of thermal behavior of the slab in the reheating furnace. The effects of different skid button height (H=60mm, 90mm, and 120mm) and different gap distance between two slabs (S=50mm, 75mm, and 100mm) on the slab skid mark formation and temperature profiles are investigated. It is found that the skid mark severity decreases with an increase in the skid button height. The effect of gap distance is important only for the slab edge planes, while it is insignificant for the slab central planes.

  5. Heat Transfer Characteristics for an Upward Flowing Supercritical Pressure CO{sub 2} in a Vertical Annulus Passage

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Deog Ji; Kim, Sin [Cheju National Univ., Cheju (Korea, Republic of); Kim, Hwan Yeol; Bae, Yoon Yeong [KAERI, Daejeon (Korea, Republic of)

    2007-07-01

    Heat transfer experiments at a vertical annulus passage were carried out in the SPHINX(Supercritical Pressure Heat Transfer Investigation for NeXt Generation) to investigate the heat transfer behaviors of supercritical CO{sub 2}. The collected test data are to be used for the reactor core design of the SCWR (SuperCritical Water-cooled Reactor). The mass flux was in the range of 400 {approx}1200 kg/m{sup 2}s and the heat flux was chosen up to 150 kW/m{sup 2}. The selected pressures were 7.75 and 8.12 MPa. The heat transfer data were analyzed and compared with the previous tube test data. The test results showed that the heat transfer characteristics were similar to those of the tube in case of a normal heat transfer mode and degree of heat transfer deterioration became smaller than that in the tube. Comparison of the experimental heat transfer coefficients with the predicted ones by the existing correlations showed that there was not a distinct difference between the correlations.

  6. Experimental study on the heat transfer characteristics of a nuclear reactor containment wall cooled by gravitationally falling water

    Science.gov (United States)

    Pasek, Ari D.; Umar, Efrison; Suwono, Aryadi; Manalu, Reinhard E. E.

    2012-06-01

    Gravitationally falling water cooling is one of mechanism utilized by a modern nuclear Pressurized Water Reactor (PWR) for its Passive Containment Cooling System (PCCS). Since the cooling is closely related to the safety, water film cooling characteristics of the PCCS should be studied. This paper deals with the experimental study of laminar water film cooling on the containment model wall. The influences of water mass flow rate and wall heat rate on the heat transfer characteristic were studied. This research was started with design and assembly of a containment model equipped with the water cooling system, and calibration of all measurement devices. The containment model is a scaled down model of AP 1000 reactor. Below the containment steam is generated using electrical heaters. The steam heated the containment wall, and then the temperatures of the wall in several positions were measure transiently using thermocouples and data acquisition. The containment was then cooled by falling water sprayed from the top of the containment. The experiments were done for various wall heat rate and cooling water flow rate. The objective of the research is to find the temperature profile along the wall before and after the water cooling applied, prediction of the water film characteristic such as means velocity, thickness and their influence to the heat transfer coefficient. The result of the experiments shows that the wall temperatures significantly drop after being sprayed with water. The thickness of water film increases with increasing water flow rate and remained constant with increasing wall heat rate. The heat transfer coefficient decreases as film mass flow rate increase due to the increases of the film thickness which causes the increasing of the thermal resistance. The heat transfer coefficient increases slightly as the wall heat rate increases. The experimental results were then compared with previous theoretical studied.

  7. Performance characteristics of a glowplug assisted low heat rejection diesel engine using ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Karthikeyan, B.; Srithar, K. [Department of Mechanical Engineering, Thiagarajar College of Engineering, Madurai, Tamilnadu 625 015 (India)

    2011-01-15

    Conventional diesel engines with ethanol as fuel are associated with problems due to high self-ignition temperature of the fuel. The hot surface ignition method, wherein a part of the injected fuel is made to touch an electrically heated hot surface (glowplug) for ignition, is an effective way of utilizing ethanol in conventional diesel engines. The purpose of the present study is to investigate the effect of thermal insulation on ethanol fueled compression ignition engine. One of the important ethanol properties to be considered in the high compression ratio engine is the long ignition delay of the fuel, normally characterized by lower cetane number. In the present study, the ignition delay was controlled by partial insulation of the combustion chamber (low heat rejection engine) by plasma spray coating of yttria stabilized zirconia for a thickness of 300 {mu}m. Experiments were carried out on the glowplug assisted engine with and without insulation in order to find out the possible benefits of combustion chamber insulation in ethanol and diesel operation. Highest brake thermal efficiency of 32% was obtained with ethanol fuel by insulating the combustion chamber. Emissions of the unburnt hydrocarbons, oxides of nitrogen and carbon monoxides were higher than that of diesel. But the smoke intensity and was less than that of diesel engine. Volumetric efficiency of the engine was reduced by a maximum of 9% in LHR mode of operation. (author)

  8. Condensing heat transfer characteristics of hydrocarbon refrigerants in 9.52 and 12.7 mm smooth tube

    Science.gov (United States)

    Yoon, Jung-In; Lee, Ho-Saeng; Lee, Kwang-Bae; Kim, Jae-Dol; Bansal, Pradeep

    2005-12-01

    Experimental results for heat transfer characteristic and pressure gradients of hydrocarbon (HC) refrigerants and R-22 during condensing inside horizontal double pipe heat exchangers are presented. The test sections which have one tube diameter of 12.70 mm with 0.86 mm wall thickness, another tube diameter of 9.52 mm with 0.76 mm wall thickness are used for this investigation. The local condensing heat transfer coefficients of HC refrigerants were higher than that of R-22. The average condensing heat transfer coefficient increased with the increase of the mass flux. It showed the higher values in HC refrigerants than R-22. Comparing the heat transfer coefficient of experimental results with that of other correlations, the presented results had a good agreement with most of the Cavallini’s correlations.

  9. CFD analysis of the two-phase bubbly flow characteristics in helically coiled rectangular and circular tube heat exchangers

    Directory of Open Access Journals (Sweden)

    Hussain Alamin

    2016-01-01

    Full Text Available Due to their ease of manufacture, high heat transfer efficiency and compact design, helically coiled heat exchangers are increasingly being adopted in a number of industries. The higher heat transfer efficiency over straight pipes is due to the secondary flow that develops as a result of the centrifugal force. In spite of the widespread use of helically coiled heat exchangers, and the presence of bubbly two-phase flow in a number of systems, very few studies have investigated the resultant flow characteristics. This paper will therefore present the results of CFD simulations for the two-phase bubbly flow in helically coiled heat exchangers as a function of the volumetric void fraction and the tube cross-section design. The CFD results are compared to the scarce flow visualisation experimental results available in the open literature.

  10. CFD analysis of the two-phase bubbly flow characteristics in helically coiled rectangular and circular tube heat exchangers

    Science.gov (United States)

    Hussain, Alamin; Fsadni, Andrew M.

    2016-03-01

    Due to their ease of manufacture, high heat transfer efficiency and compact design, helically coiled heat exchangers are increasingly being adopted in a number of industries. The higher heat transfer efficiency over straight pipes is due to the secondary flow that develops as a result of the centrifugal force. In spite of the widespread use of helically coiled heat exchangers, and the presence of bubbly two-phase flow in a number of systems, very few studies have investigated the resultant flow characteristics. This paper will therefore present the results of CFD simulations for the two-phase bubbly flow in helically coiled heat exchangers as a function of the volumetric void fraction and the tube cross-section design. The CFD results are compared to the scarce flow visualisation experimental results available in the open literature.

  11. Studies on the characteristics of the separated heat pipe system with non-condensible gas for the use of the passive decay heat removal in reactor systems

    International Nuclear Information System (INIS)

    Hayashi, Takao; Ishi, Takayuki; Hayakawa, Hitoshi; Ohashi, Kazutaka

    1997-01-01

    Experiments on the separated heat pipe system of variable conductance type, which enclose non-condensible gas, have been carried out with intention of applying such system to passive decay heat removal of the modular reactors such as HTR plant. Basic experiments have been carried out on the experimental apparatus consisting of evaporator, vapor transfer tube, condenser tube and return tube which returns the condensed liquid back to the evaporator. Water and methanol were examined as the working fluids and nitrogen gas was enclosed as the non-condensible gas. The behaviors of the system were examined for the parametric changes of the heat input under the various pressures of nitrogen gas initially enclosed, including the case without enclosing N 2 gas for the comparison. The results of the experiments shows very clear features of self control characteristics. The self control mechanism was made clear, that is, in such system in which the condensing area in the condenser expands automatically in accordance with the increase of the heat input to keep the system temperature nearly constant. The working temperature of the system are clearly dependent on the pressure of the non-condensable gas initially enclosed, with higher system working temperature with higher initial gas pressure enclosed. The analyses were done on water and methanol as the working fluids, which show very good agreement with the experimental results. A lot of attractive applications are expected including the self switching feature with minimum heat loss during normal operation with maintaining the sufficient heat removal at accidents. (author)

  12. Influence of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in cyclone heat exchanger

    International Nuclear Information System (INIS)

    Mothilal, T.; Pitchandi, K.

    2015-01-01

    Present work elaborates the effect of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in a cyclone heat exchanger. The RNG k-ε turbulence model was adopted for modeling high turbulence flow and Discrete phase model (DPM) to track solid particles in a cyclone heat exchanger by ANSYS FLUENT software. The effect of inlet air velocity (5 to 25 m/s) and inlet solid particle feed rate of (0.2 to 2.5 g/s) at different particle diameter (300 to 500 μm) on holdup mass and heat transfer rate in cyclone heat exchanger was studied at air inlet temperature of 473 K. Results show that holdup mass and heat transfer rate increase with increase in inlet air velocity and inlet solid particle feed rate. Influence of solid particle feed rate on holdup mass has more significance. Experimental setup was built for high efficiency cyclone. Good agreement was found between experimental and simulation pressure drop. Empirical correlation was derived for dimensionless holdup mass and Nusselt number based on CFD data by regression technique. Correlation predicts dimensional holdup mass with +5% to -8% errors of experimental data and Nusselt number with +9% to -3%

  13. Influence of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in cyclone heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Mothilal, T. [T. J. S. Engineering College, Gummidipoond (India); Pitchandi, K. [Sri Venkateswara College of Engineering, Sriperumbudur (India)

    2015-10-15

    Present work elaborates the effect of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in a cyclone heat exchanger. The RNG k-ε turbulence model was adopted for modeling high turbulence flow and Discrete phase model (DPM) to track solid particles in a cyclone heat exchanger by ANSYS FLUENT software. The effect of inlet air velocity (5 to 25 m/s) and inlet solid particle feed rate of (0.2 to 2.5 g/s) at different particle diameter (300 to 500 μm) on holdup mass and heat transfer rate in cyclone heat exchanger was studied at air inlet temperature of 473 K. Results show that holdup mass and heat transfer rate increase with increase in inlet air velocity and inlet solid particle feed rate. Influence of solid particle feed rate on holdup mass has more significance. Experimental setup was built for high efficiency cyclone. Good agreement was found between experimental and simulation pressure drop. Empirical correlation was derived for dimensionless holdup mass and Nusselt number based on CFD data by regression technique. Correlation predicts dimensional holdup mass with +5% to -8% errors of experimental data and Nusselt number with +9% to -3%.

  14. Conjugate Heat Transfer Characteristics of Laminar Flows Through a Backward Facing Step Duct

    Directory of Open Access Journals (Sweden)

    Bayram CELİK

    2017-10-01

    Full Text Available Present study investigates the effects of solid to fluid conductivity ratio, Prandtl and Reynolds numbers, and solid wall thickness on conjugate heat transfer for a backward facing step duct with a conductive solid bottom wall. Although Kanna and Das performed a case study in 2006 for the same problem, the benchmark studies conducted later including the present one revealed that their results are arguable. Ramsak states in a study “Professor Kanna has confirmed in personal communication that their results are probably wrong”. The temperature and Nusselt number variations along the solid-fluid interface presented here are in excellent agreement with those obtained by Ramsak. The analyses presented here reveal that even though the decrease in Pr and the increase in solid to fluid conductivity ratio have similar global influence with the thinning wall on the interface temperature, the influence of the former parameters are limited in recirculation zone.

  15. Antioxidant and Anti-Inflammatory Activities of Hydrolysates and Peptide Fractions Obtained by Enzymatic Hydrolysis of Selected Heat-Treated Edible Insects.

    Science.gov (United States)

    Zielińska, Ewelina; Baraniak, Barbara; Karaś, Monika

    2017-09-02

    This study investigated the effect of heat treatment of edible insects on antioxidant and anti-inflammatory activities of peptides obtained by in vitro gastrointestinal digestion and absorption process thereof. The antioxidant potential of edible insect hydrolysates was determined as free radical-scavenging activity, ion chelating activity, and reducing power, whereas the anti-inflammatory activity was expressed as lipoxygenase and cyclooxygenase-2 inhibitory activity. The highest antiradical activity against DPPH • (2,2-diphenyl-1-picrylhydrazyl radical) was noted for a peptide fraction from baked cricket Gryllodes sigillatus hydrolysate (IC 50 value 10.9 µg/mL) and that against ABTS •+ (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical) was the highest for raw mealworm Tenebrio molitor hydrolysate (inhibitory concentration (IC 50 value) 5.3 µg/mL). The peptides obtained from boiled locust Schistocerca gregaria hydrolysate showed the highest Fe 2+ chelation ability (IC 50 value 2.57 µg/mL); furthermore, the highest reducing power was observed for raw G. sigillatus hydrolysate (0.771). The peptide fraction from a protein preparation from the locust S. gregaria exhibited the most significant lipoxygenase and cyclooxygenase-2 inhibitory activity (IC 50 value 3.13 µg/mL and 5.05 µg/mL, respectively).

  16. Seasonal and Spatial Characteristics of Urban Heat Islands (UHIs in Northern West Siberian Cities

    Directory of Open Access Journals (Sweden)

    Victoria Miles

    2017-09-01

    Full Text Available Anthropogenic heat and modified landscapes raise air and surface temperatures in urbanized areas around the globe. This phenomenon is widely known as an urban heat island (UHI. Previous UHI studies, and specifically those based on remote sensing data, have not included cities north of 60°N. A few in situ studies have indicated that even relatively small cities in high latitudes may exhibit significantly amplified UHIs. The UHI characteristics and factors controlling its intensity in high latitudes remain largely unknown. This study attempts to close this knowledge gap for 28 cities in northern West Siberia (NWS. NWS cities are convenient for urban intercomparison studies as they have relatively similar cold continental climates, and flat, rather homogeneous landscapes. We investigated the UHI in NWS cities using the moderate-resolution imaging spectroradiometer (MODIS MOD 11A2 land surface temperature (LST product in 8-day composites. The analysis reveals that all 28 NWS cities exhibit a persistent UHI in summer and winter. The LST analysis found differences in summer and winter regarding the UHI effect, and supports the hypothesis of seasonal differences in the causes of UHI formation. Correlation analysis found the strongest relationships between the UHI and population (log P. Regression models using log P alone could explain 65–67% of the variability of UHIs in the region. Additional explanatory power—at least in summer—is provided by the surrounding background temperatures, which themselves are strongly correlated with latitude. The performed regression analysis thus confirms the important role of the surrounding temperature in explaining spatial–temporal variation of UHI intensity. These findings suggest a climatological basis for these phenomena and, given the importance of climatic warming, an aspect that deserves future study.

  17. Study on the 21 MeV neutron flux characteristics obtained in the 3H(d,n)4He reaction using of gas target

    International Nuclear Information System (INIS)

    Lovchikova, G.N.; Polyakov, A.V.; Sal'nikov, O.A.; Simakov, S.P.; Sukhikh, S.Eh.; Trufanov, A.M.

    1983-01-01

    The possibility to use gas tritium target as neutron source with the energy 2 MeV for nuclear-physical studies has been considered. Characteristics of neutron flux crested in the reaction 3 H(d, n) 4 He to obtain neutrons are investigated. The study of inelastic scattering processes at the energies permits to expand the experiments conducted up to the present day on the study of spectra of inelastically scattered neutrons in a lower energy region and it is of interest for the clarification of appearance mechanism of high-energy neutrons in the spectra. Characteristics of neutron flux as a result of the reaction 3 (α, n) 4 He at the energy of falling deuterons Esub(d)=5.54 MeV are investigated. Measurements of spectra of scattered neutrons on carbon-12 at the angles 30, 45, 60, 90, 120, 150 degrees are made. Differential cross sections of elastic scattering are obtained

  18. Analytical characterization of products obtained from slow pyrolysis of Calophyllum inophyllum seed cake: study on performance and emission characteristics of direct injection diesel engine fuelled with bio-oil blends.

    Science.gov (United States)

    Rajamohan, Sakthivel; Kasimani, Ramesh

    2018-04-01

    This paper aims to analyse the characteristics and properties of the fractions obtained from slow pyrolysis of non-edible seed cake of Calophyllum inophyllum (CI). The gas, bio-oil and biochar obtained from the pyrolysis carried out at 500 °C in a fixed bed batch type reactor at a heating rate of 30 °C/min were characterized by various analytical techniques. Owing to the high volatile content of CI biomass (72.61%), it was selected as the raw material in this present investigation. GC-MS and FT-IR analysis of bio-oil showed the presence of higher amount of oxygenated compounds, phenol derivatives, esters, acid and furans. The physicochemical properties of the bio-oil were tested as per ASTM norms which imply that bio-oil is a highly viscous liquid with lower heating value as compared to that of diesel fuel. The chemical composition of evolved gas was analysed by using GC testing which revealed the presence of combustible components. The FT-IR characterization of biochar showed the presence of aliphatic and aromatic hydrocarbons whereas the elevated amount of carbon in biochar indicates its potential to be used as solid fuel. The performance and emission characteristics of CI engine were assessed with different CI bio-oil blends and compared with baseline diesel fuel. The results showed that addition of bio-oil leads to decreased brake thermal efficiency and increased brake specific energy consumption. Meanwhile, increase in blend ratio reduces harmful pollutants such as oxides of nitrogen and smoke in the exhaust. From the engine testing, it is suggested to employ 20% of CI bio-oil blends in CI engine to obtain better operation.

  19. Use of nuclear process heat from pebble bed high temperature reactors to obtain oil by tertiary recovery methods. Final report. Vol. 2

    International Nuclear Information System (INIS)

    Jaeger, H.; Hermges, H.; Kammel, R.; Kugeler, K.; Phlippen, P.W.; Scheuch, H.; Schmidt, F.; Schmidtlein, P.; Schreiner, P.

    1988-01-01

    Volume II of this report examines: 1. The use of nuclear process heat in the further processing of crude oil (refinery processes, heat coupling, steam reforming helium-heated pipe furnace), 2. Analyses for process questions, 3. Questions of economy, 4. Environmental aspects, 5. Work on underground methanisation. (RB) [de

  20. A study on the characteristics of the decay heat removal capacity for a large thermal rated LMR design

    International Nuclear Information System (INIS)

    Uh, J. H.; Kim, E. K.; Kim, S. O.

    2003-01-01

    The design characteristics and the decay heat removal capacity according to the type of DHR (Decay Heat Removal) system in LMR are quantitatively analyzed, and the general relationship between the rated core thermal power and decay heat removal capacity is created in this study. Based on these analyses results, a feasibility of designing a larger thermal rating KALIMER plant is investigated in view of decay heat removal capacity, and DRC (Direct Reactor Cooling) type DHR system which rejects heat from the reactor pool to air is proper to satisfy the decay heat removal capacity for a large thermal rating plant above 1,000 MWth. Some defects, however, including the heat loss under normal plant operation and the lack of reliance associated with system operation should be resolved in order to adopt the total passive concept. Therefore, the new concept of DHR system for a larger thermal rating KALIMER design, named as PDRC (passive decay heat removal circuit), is established in this study. In the newly established concept of PDRC, the Na-Na heat exchanger is located above the sodium cold pool and is prevented from the direct sodium contact during normal operation. This total passive feature has the superiority in the aspect of the minimizing the normal heat loss and the increasing the operation reliance of DHR system by removing either any operator action or any external operation signal associated with system operation. From this study, it is confirmed that the new concept of PDRC is useful to the designing of a large thermal rating power plant of KALIMER-600 in view of decay heat removal capability

  1. Cytotoxic characteristics of biodegradable EW10X04 Mg alloy after Nd coating and subsequent heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Katarivas Levy, Galit [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Ventura, Yvonne [Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Goldman, Jeremy [Biomedical Engineering Department, Michigan Technological University, Houghton, MI 49931 (United States); Vago, Razi [Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Aghion, Eli [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2016-05-01

    Porous Mg scaffolds are considered as potential bone growth promoting materials. Unfortunately, the high rate of biocorrosion inherent to Mg alloys may cause a premature loss of mechanical strength, excessive evolution of hydrogen gas, and a rapidly shifting surface topography, all of which may hinder the ability of native cells to attach and grow on the implant surface. Here we investigated the cell cytotoxicity effects during corrosion of a novel magnesium alloy, EW10X04 (Mg–1.2%Nd–0.5%Y–0.5%Zr–0.4%Ca), following diffusion coating (DC) and heat treatment to reduce the corrosion rate. Cells were exposed either to corrosion products or to the corroding scaffold surface, in vitro. The microstructure characterization of the scaffold surface was carried out by scanning electron microscopy (SEM) equipped with a Noran energy dispersive spectrometer (EDS). Phase analyses were obtained by X-ray diffraction (XRD). We found that cell viability, growth, and adhesion were all improved when cultured on the EW10X04 + DC surface or under corrosion product extracts due to lower corrosion rates relative to the EW10X04 control samples. It is therefore believed that the tested alloy after Nd coating and heat treatment may introduce a good balance between its biodegradation characteristics and cytotoxic effects towards cells. - Highlights: • The effects of a diffusion coating (DC) with Nd on cell cytotoxicity is shown. • A novel EW10X04 (Mg–1.2%Nd–0.5%Y–0.5%Zr–0.4%Ca) magnesium alloy with DC was tested. • Cell viability, growth, and adhesion were reduced on the control vs. DC surface. • The DC alloy may introduce a good balance between biodegradation and cytotoxicity.

  2. Cytotoxic characteristics of biodegradable EW10X04 Mg alloy after Nd coating and subsequent heat treatment

    International Nuclear Information System (INIS)

    Katarivas Levy, Galit; Ventura, Yvonne; Goldman, Jeremy; Vago, Razi; Aghion, Eli

    2016-01-01

    Porous Mg scaffolds are considered as potential bone growth promoting materials. Unfortunately, the high rate of biocorrosion inherent to Mg alloys may cause a premature loss of mechanical strength, excessive evolution of hydrogen gas, and a rapidly shifting surface topography, all of which may hinder the ability of native cells to attach and grow on the implant surface. Here we investigated the cell cytotoxicity effects during corrosion of a novel magnesium alloy, EW10X04 (Mg–1.2%Nd–0.5%Y–0.5%Zr–0.4%Ca), following diffusion coating (DC) and heat treatment to reduce the corrosion rate. Cells were exposed either to corrosion products or to the corroding scaffold surface, in vitro. The microstructure characterization of the scaffold surface was carried out by scanning electron microscopy (SEM) equipped with a Noran energy dispersive spectrometer (EDS). Phase analyses were obtained by X-ray diffraction (XRD). We found that cell viability, growth, and adhesion were all improved when cultured on the EW10X04 + DC surface or under corrosion product extracts due to lower corrosion rates relative to the EW10X04 control samples. It is therefore believed that the tested alloy after Nd coating and heat treatment may introduce a good balance between its biodegradation characteristics and cytotoxic effects towards cells. - Highlights: • The effects of a diffusion coating (DC) with Nd on cell cytotoxicity is shown. • A novel EW10X04 (Mg–1.2%Nd–0.5%Y–0.5%Zr–0.4%Ca) magnesium alloy with DC was tested. • Cell viability, growth, and adhesion were reduced on the control vs. DC surface. • The DC alloy may introduce a good balance between biodegradation and cytotoxicity.

  3. Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

    International Nuclear Information System (INIS)

    Zhang, S; Sobota, A; Van Veldhuizen, E M; Bruggeman, P J

    2015-01-01

    This work investigates the flow dynamics of a radio-frequency (RF) non-equilibrium argon atmospheric pressure plasma jet. The RF power is at a frequency of 50 Hz or 20 kHz. Combined flow pattern visualizations (obtained by shadowgraphy) and gas temperature distributions (obtained by Rayleigh scattering) are used to study the formation of transient vortex structures in initial flow field shortly after the plasma is switched on and off in the case of 50 Hz modulation. The transient vortex structures correlate well with observed temperature differences. Experimental results of the fast modulated (20 kHz) plasma jet that does not induce changes of the gas temperature are also presented. The latter result suggests that momentum transfer by ions does not have dominant effect on the flow pattern close to the tube. It is argued that the increased gas temperature and corresponding gas velocity increase at the tube exit due to the plasma heating increases the admixing of surrounding air and reduces the effective potential core length. With increasing plasma power a reduction of the effective potential core length is observed with a minimum length for 5.6 W after which the length extends again. Possible mechanisms related to viscosity effects and ionic momentum transfer are discussed. (paper)

  4. Characteristics of turbulent heat transfer in an annulus at supercritical pressure

    NARCIS (Netherlands)

    Peeters, J.W.R.; Pecnik, R.; Rohde, M.; van der Hagen, T.H.J.J.; Boersma, B.J.

    2017-01-01

    Heat transfer to fluids at supercritical pressure is different from heat transfer at lower pressures due to strong variations of the thermophysical properties with the temperature. We present and analyze results of direct numerical simulations of heat transfer to turbulent CO2 at 8 MPa in an

  5. Numerical investigation of fluid flow and heat transfer characteristics in a helically-finned tube

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sangkeun; Kim, Minsung; Park, Yong Gap; Min, June Kee; Ha, Man Yeong [Pusan National University, Busan (Korea, Republic of)

    2017-07-15

    In order to investigate the characteristics of flow and heat transfer rate in a Helically-finned tub (HFT), we used continuity, momentum and energy equations under a steady, three-dimensional and incompressible fluid flow assumptions. For the performance metrics, we considered the Darcy friction factor, Colburn j-factor, volume goodness factor and area goodness factor of the HFT. We could also evaluate the effect of geometry parameters on the results of local pressure coefficient, fluid vorticity and Nusselt number of the HFT. We carried out the CFD calculation for a range of laminar flow (Re = 100) and turbulent flow (Re = 2000 and 10000). In a laminar and turbulent flow regime, the friction factor increases with increasing the each geometric parameter. While the Colburn j-factor decreases as increasing these geometric parameters. Consequently, the thermal performance of HFT is poorer than that of single straight circular tube type because of having a small volume and area goodness factor as increasing the Reynolds numbers.

  6. Heat deposition, damage, and tritium breeding characteristics in thick liquid wall blanket concepts

    International Nuclear Information System (INIS)

    Youssef, M.Z.; Abdou, M.A.

    2000-01-01

    The advanced power extraction (APEX) study aims at exploring new and innovative blanket concepts that can efficiently extract power from fusion devices with high neutron wall load. Among the concepts under investigation is the free liquid FW/liquid blanket concept in which a fast flowing liquid FW (∼2-3 cm) is followed by thick flowing blanket (B) of ∼40-50 cm thickness with minimal amount of structure. The liquid FW/B are contained inside the vacuum vessel (VV) with a shielding zone (S) located either behind the VV and outside the vacuum boundary (case A) or placed after the FW/B and inside the VV (case B). In this paper we investigate the nuclear characteristics of this concept in terms of: (1) attenuation capability of the liquid FW/B/S and protection of the VV and magnet against radiation damage; (2) profiles of tritium production rate and tritium breeding ratio (TBR) for several liquid candidates; and (3) profiles of heat deposition rate and power multiplication. The candidate liquid breeders considered are Li, Flibe, Li-Sn, and Li-Pb. Parameters varied are (1) FW/B thickness, L, (2) Li-6 enrichment and (3) thickness of the shield

  7. Transition Heat Transfer Modeling Based on the Characteristics of Turbulent Spots

    Science.gov (United States)

    Simon, Fred; Boyle, Robert

    1998-01-01

    While turbulence models are being developed which show promise for simulating the transition region on a turbine blade or vane, it is believed that the best approach with the greatest potential for practical use is the use of models which incorporate the physics of turbulent spots present in the transition region. This type of modeling results in the prediction of transition region intermittency which when incorporated in turbulence models give a good to excellent prediction of the transition region heat transfer. Some models are presented which show how turbulent spot characteristics and behavior can be employed to predict the effect of pressure gradient and Mach number on the transition region. The models predict the spot formation rate which is needed, in addition to the transition onset location, in the Narasimha concentrated breakdown intermittency equation. A simplified approach is taken for modeling turbulent spot growth and interaction in the transition region which utilizes the turbulent spot variables governing transition length and spot generation rate. The models are expressed in terms of spot spreading angle, dimensionless spot velocity, dimensionless spot area, disturbance frequency and Mach number. The models are used in conjunction with a computer code to predict the effects of pressure gradient and Mach number on the transition region and compared with VKI experimental turbine data.

  8. Development Characteristics of Velocity Transports in An Isothermal Heated Drag-Reducing Surfactant Solution Flow

    Science.gov (United States)

    Zhang, Hongxia; Wang, Dezhong; Chen, Hanping; Wang, Yanping

    2007-06-01

    The development characteristics, turbulence transports for stresses and kinetic energy of a cetyltrimethyl ammonium chloride (CTAC) surfactant solution for a two-dimensional channel flow have been experimentally investigated. Time mean velocity and fluctuating velocity are measured using a Phase Doppler Anemometry (PDA) at the Reynolds number 1.78×104 and isothermal heated temperature 31°C. Although mean velocity profiles at three cross sections show that the fluid is almost fully developed, the peak location of fluctuating intensity for the CTAC solution is slightly away from the wall downstream from the fluid and the peak location of fluctuating intensity is observed at far away from the wall than that of water. The location where the velocity gradient has its maximum, the fluctuating intensity does not get the high value. The elastic shear stress contribution to the total shear stress is 15 percents to 36 percents and it gets to the maximum near to the wall. The surfactant elastic shear stress is almost a liner function of the height of the channel, which means that the elastic stress contribution of the different cross locations is approximately the same. The fluctuating surfactant stress work is negative and the fluctuating elastic shear stresses produce rather than dissipate kinetic energy.

  9. Performance characteristics of a combination solar photovoltaic heat engine energy converter

    Science.gov (United States)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  10. Determination of thermal characteristics of combustion products of fire-tube heat generator with flow turbulator

    OpenAIRE

    Lukjanov Alexander V.; Ostapenko Dmitry V.; Basist Dmitry V.

    2014-01-01

    Boiler construction is one of the major industries of any state. The aim is to determine the effect of the turbulator on the intensity of heat transfer in the convective part of the fire-tube heat generator of domestic production. The improvement of convective heating surfaces is one of the ways to increase the energy efficiency of the fire-tube heat generator. Since model of the process of heat transfer of gas flow in the convective tubes is multifactorial and does not have clear analytical ...

  11. Effects of Two-stage Heat Treatment on Delayed Coke and Study of Their Surface Texture Characteristics

    Science.gov (United States)

    Im, Ui-Su; Kim, Jiyoung; Lee, Seon Ho; Lee, Byung-Rok; Peck, Dong-Hyun; Jung, Doo-Hwan

    2017-12-01

    In the present study, surface texture features and chemical properties of two types of cokes, made from coal tar by either 1-stage heat treatment or 2-stage heat treatment, were researched. The relationship between surface texture characteristics and the chemical properties was identified through molecular weight distribution, insolubility of coal tar, weight loss with temperature increase, coking yield, and polarized light microscope analysis. Rapidly cleared anisotropy texture in cokes was observed in accordance with the coking temperature rise. Quinoline insolubility and toluene insolubility of coal tar increased with a corresponding increases in coking temperature. In particular, the cokes produced by the 2-stage heat treatment (2S-C) showed surface structure of needle cokes at a temperature approximately 50°C lower than the 1-stage heat treatment (1S-C). Additionally, the coking yield of 2S-C increased by approximately 14% in comparison with 1S-C.

  12. Effect of heating rate on thermal cracking characteristics and kinetics of Xinjiang oil sand bitumen by TG-FTIR

    Science.gov (United States)

    Hao, Junhui; Zhang, Jinhong; Qiao, Yingyun; Tian, Yuanyu

    2017-08-01

    This work was aimed to investigate effects of heating rate on thermal cracking behaviors, distribution of gaseous products and activation energy of the thermal cracking process of Xinjiang oil sand bitumen (OSB). The thermal cracking experiments of Xinjiang OSB were performed by using thermogravimetric analyzer (TGA) at various heating rates of 10, 20, 50, 80 and 120 K/min. The evolving characteristic of gaseous products produced from the thermal cracking process was evaluated by the Fourier transform infrared spectrometry (FTIR) connected with TG. The kinetic parameters of the thermal cracking process of Xinjiang OSB at each of heating rate were determined by the Coats-Redfern model. The result show that the temperature intervals of DE volatilization stage and main reaction stage, the ((dw/dt) max and Tmax in thermal cracking process of Xinjiang OSB all increased with the increasing heating rate. While the heating rate has not obvious effect on the coke yield of Xinjiang OSB. Furthermore, the maximum absorbance of gaseous products and corresponding temperature became larger as the heating rate increases. The activation energy of this two stage both presented increasing trend with the rising heating rate, while the increasing content of that of DE volatilization stage was weaker compared to that of main reaction stage.

  13. Experimental research on thermal characteristics of a hybrid thermocline heat storage system

    International Nuclear Information System (INIS)

    Yin, Huibin; Ding, Jing; Yang, Xiaoxi

    2014-01-01

    Considering the high-temperature thermal utilization of solar energy as the research background in this paper and focussing on the heat storage process, a kind of hybrid thermocline heat storage method in multi-scale structure and relevant experimental systems are designed by using the mixed molten nitrate salt as the heat storage medium and two representative porous materials, i.e. zirconium ball and silicon carbide (SiC) foam, as the heat storage fillers. The fluid flow and heat storage performance of molten salt in multi-scale structure are experimentally investigated. The results show that the theoretical heat storage efficiencies amongst the three experimental heat storage manners are less than 80% because of the existence of thermocline layers. Comparing to the single-phase molten salt heat storage, the two hybrid thermocline heat storage manners with porous fillers lead to a certain decrease in the effective heat storage capacity. The presence of porous fillers can also help to maintain the molten salt fluid as ideal gravity flow or piston flow and partially replace expensive molten salt. Therefore, it requires a combination of heat storage capacity and economical consideration for optimization design when similar spherical particles or foam ceramics are employed as the porous fillers. -- Highlights: • A hybrid thermocline heat storage method in multi-scale structure is developed. • The fluid flow and heat storage performance are experimentally investigated. • Stable thermocline can form in single tank for the experimental cases. • The hybrid thermocline heat storage with porous filler is promising

  14. Investigating effects of BCC and FCC arrangements on flow and heat transfer characteristics in pebbles through CFD methodology

    Energy Technology Data Exchange (ETDEWEB)

    Ferng, Yuh Ming, E-mail: ymferng@ess.nthu.edu.tw [Department of Engineering and System Science, Institute of Nuclear Engineering and Science, National Tsing Hua University, 101, Sec. 2. Kuang-Fu Rd., Hsingchu 30013, Taiwan, ROC (China); Lin, Kun-Yueh [Department of Engineering and System Science, Institute of Nuclear Engineering and Science, National Tsing Hua University, 101, Sec. 2. Kuang-Fu Rd., Hsingchu 30013, Taiwan, ROC (China)

    2013-05-15

    Highlights: ► An HTGR would be one of the possible energy generation sources. ► We propose a CFD model to study effects of pebble arrangements for a PRB core. ► The entrance effect on the Nu number can be reasonably captured. ► The present predicted Nu versus Re{sub p} shows good agreement with data and correlation. ► Using FCC lattice in a core, simulation results may be non-conservative. -- Abstract: A high temperature gas cooled reactor (HTGR) would be one of the possible energy generation sources due to its advantages of inherently safety performance and higher conversion efficiency, etc. However, safety is the most important issue for its commercialization in energy industry. It is very crucial for safety design and operation of an HTGR to investigate its thermal–hydraulic characteristics. In this article, a computational fluid dynamics (CFD) methodology is proposed to investigate effects of different arrangements on these characteristics for an HTGR with a pebble bed (PB) core. Two kinds of arrangement: body-centered cubic (BCC) and face-centered cubic (FCC) are studies herein. Based on the simulation results, higher heat transfer capability and lower pebble temperature are predicted in the pebbles with the FCC-arrangement. The thermally fully-developed flow condition may be reached, which is shown in the result that the predicted average Nussel (Nu) number decreases from the 1st layer and reaches to an asymptotic value as the gas passes through the 6th layer of pebbles. This entrance effect reveals that the system codes using the correlations developed from the fully-developed flow condition can be appropriately applied in the entire PBR core. In addition, the present predicted dependence of Nu number on the inlet Reynolds (Re) number shows good agreement with that obtained from the well-known KTA. Measured data of Nu number versus Re number are also used to validate the CFD model.

  15. Determination of Sliced Pineapple Drying Characteristics in A Closed Loop Heat Pump Assisted Drying System

    Directory of Open Access Journals (Sweden)

    Cüneyt Tunçkal

    2018-02-01

    Full Text Available Pineapple (Ananascomosus slices were dried with the aid of a heat pump assisted dryer (HPD. During this process, air velocity was kept constant at 1m/s, while air temperatures were changed as 37°C, 40°C and 43°C. The drying air was also circulated by using an axial fan in a closed cycle and fresh air was not allowed into the system. The drying rate and drying time were significantly influenced by drying temperature. It was observed that drying temperatures had significant effects on the drying rate and drying time. During the conduct of the study, pineapple slices were dried at 37, 40 and 43°C for 465, 360 and 290 min, respectively. The specific moisture extraction ratio (SMER values were observed to change as drying temperatures were changed. The drying rate curves indicated that the whole drying process occurred in the falling rate period. Seven well-known thin-layer models (Lewis, Henderson &Pabis, Logarithmic, Page, Midilli & Kucuk, Weibull and Aghbashlo et al. were employed to make a prediction about drying kinetics through nonlinear regression analysis. The Midilli & Kucuk and Aghbashlo et al. models were consistent with the experimental data. Fick’s second law of diffusion was used to determine the moisture diffusivity coefficient ranging from 3.78×10–9 to 6.57×10-9  m2/s the each of the above mentioned temperatures. The dependence of effective diffusivity coefficient on temperature was defined by means a fan Arrhenius type equation. The activation energy of moisture diffusion was found to be 75.24kJ/mol.   Article History: Received: July 18th 2017; Received: October 27th 2017; Accepted: January 16th 2018; Available online How to Cite This Article: Tunçkal, C., Coşkun, S., Doymaz, I. and Ergun, E. (2018 Determination of Sliced Pineapple Drying Characteristics in A Closed Loop Heat Pump Assisted Drying System. International Journal of Renewable Energy Development, 7(1, 35-41. https://doi.org/10.14710/ijred.7.1.35-41

  16. Projected Heat Wave Characteristics over the Korean Peninsula During the Twenty-First Century

    Science.gov (United States)

    Shin, Jongsoo; Olson, Roman; An, Soon-Il

    2018-02-01

    Climate change is expected to increase temperatures globally, and consequently more frequent, longer, and hotter heat waves are likely to occur. Ambiguity in defining heat waves appropriately makes it difficult to compare changes in heat wave events over time. This study provides a quantitative definition of a heat wave and makes probabilistic heat wave projections for the Korean Peninsula under two global warming scenarios. Changes to heat waves under global warming are investigated using the representative concentration pathway 4.5 (RCP4.5) and 8.5 (RCP8.5) experiments from 30 coupled models participating in phase five of the Coupled Model Inter-comparison Project. Probabilistic climate projections from multi-model ensembles have been constructed using both simple and weighted averaging. Results from both methods are similar and show that heat waves will be more intense, frequent, and longer lasting. These trends are more apparent under the RCP8.5 scenario as compared to the RCP4.5 scenario. Under the RCP8.5 scenario, typical heat waves are projected to become stronger than any heat wave experienced in the recent measurement record. Furthermore, under this scenario, it cannot be ruled out that Korea will experience heat wave conditions spanning almost an entire summer before the end of the 21st century.

  17. Three-dimensional numerical study of heat transfer characteristics of plain plate fin-and-tube heat exchangers from view point of field synergy principle

    International Nuclear Information System (INIS)

    He, Y.L.; Tao, W.Q.; Song, F.Q.; Zhang, W.

    2005-01-01

    In this paper, 3-D numerical simulations were performed for laminar heat transfer and fluid flow characteristics of plate fin-and-tube heat exchanger. The effects of five factors were examined: Re number, fin pitch, tube row number, spanwise and longitudinal tube pitch. The Reynolds number based on the tube diameter varied from 288 to 5000, the non-dimensional fin pitch based on the tube diameter varied from 0.04 to 0.5, the tube row number from 1 to 4, the spanwise tube pitch S 1 /d varies from 1.2 to 3, and the longitudinal tube pitch S 2 /d from 1.0 to 2.4. The numerical results were analyzed from the view point of field synergy principle, which says that the reduction of the intersection angle between velocity and fluid temperature gradient is the basic mechanism to enhance convective heat transfer. It is found that the effects of the five parameters on the heat transfer performance of the finned tube banks can be well described by the field synergy principle, i.e., the enhancement or deterioration of the convective heat transfer across the finned tube banks is inherently related to the variation of the intersection angle between the velocity and the fluid temperature gradient. It is also recommended that to further enhance the convective heat transfer, the enhancement techniques, such as slotting the fin, should be adopted mainly in the rear part of the fin where the synergy between local velocity and temperature gradient become worse

  18. Proposal of a technical guide for the evaluation and management of the solitary pulmonary nodule in function of the radiological characteristics obtained by computed tomography

    International Nuclear Information System (INIS)

    Clinton Hidalgo, Carolina

    2015-01-01

    A guide is proposed to guide clinical personnel in early diagnosis, assessment and management of the solitary pulmonary nodule, with high potential of to develop lung cancer, in function of the radiological characteristics obtained by computed tomography. The management of patients with diagnosis of solitary pulmonary nodule is standardized with the purpose of to unify diagnostic criteria in a multidisciplinary and institutional environment. Tomographic radiological characteristics are described to allow the suspicion of the solitary pulmonary nodule benignity or malignity. A flow diagram is developed to guide the physician to an adequate monitoring, control and eventual therapeutic treatment. A clear and structured perspective of the diagnostic and therapeutic process is provided to the treating physician and patient [es

  19. Comparison and validation of dynamic characteristic analytical method for tubular heat exchanger

    International Nuclear Information System (INIS)

    Huang Qing; Xu Dinggeng; Chen Meng; Shen Rui

    2013-01-01

    In this study, the natural frequencies of Normal Residual Heat Removal Heat Exchangers are evaluated based on the beam and shell-beam finite element models. The corresponding results are compared and some discrepancies are observed. These discrepancies are analyzed in terms of the analysis of a cylindrical shell and the unreasonable treatment of boundary conditions is accordingly pointed out. The experimental data of the natural frequencies of heat exchangers used for Qinshan Phase Ⅰ Nuclear Power Plant are compared with the computational results from the shell-beam models for corresponding heat exchangers of C-2 program. The experimental and numerical results agree quite well, which implies that the shell-beam finite element simplification is applicable to the heat exchangers. The results indicate that the procedures introduced in this article apply to the dynamic analysis of other similar heat exchangers. (authors)

  20. Ferrocyanide safety program: Heat load and thermal characteristics determination for selected tanks

    International Nuclear Information System (INIS)

    McLaren, J.M.; Cash, R.J.

    1993-11-01

    An analysis was conducted to determine the heat loads, conductivities, and heat distributions of waste tanks 241-BY-105, -106, -108, -110, -111, and 241-C-109 at the Hanford Site. The heat distribution of tank 241-BY-111 was determined to be homogeneously distributed throughout the sludge contained in the tank. All of the other tanks, with the exception of 241-C-109, showed evidence of a heat-producing layer at the bottom of the tanks. No evidence of a heat-producing layer in a position above the bottom was found. The thermal conductivities were determined to be within the ranges found by previous laboratory and computer analysis. The heat loads of the tanks were found to be below 2.81 kW (9,600 Btu/hr)

  1. Effect of slip on heat transfer and entropy generation characteristics of simplified Phan-Thien–Tanner fluids with viscous dissipation under uniform heat flux boundary conditions: Exponential formulation

    International Nuclear Information System (INIS)

    Anand, Vishal

    2016-01-01

    Highlights: • Exponential formulation of s-PTT model used. • Heat transfer and entropy generation characteristics studied. • Effects of three slip laws examined. • Exponential formulation more accurate than linear formulation. - Abstract: This study concerns the heat transfer and entropy generation characteristics of viscoelastic fluid flow modeled by the exponential formulation of simplified Phan-Thien–Tanner (s-PTT) model. This is the first such study in literature of thermal behavior of viscoelastic fluids modeled by the exponential formulation of s-PTT model. The flow between two parallel plates is laminar, hydrodynamically and thermally fully developed, viscous dissipative and subject to uniform heat flux on the walls. The slip velocity boundary condition is imposed on the fluid–solid interface and the slip is captured by three slip laws, namely, Navier's non-linear slip law, Hatzikiriakos slip law, and asymptotic slip law. The governing equations have been solved analytically. Closed form solutions for the velocity distribution have been derived while the temperature distribution is presented in terms of an infinite but convergent series. The results pertaining to the three slip laws have been presented in detail. Finally, a comparison has been made between the results for exponential formulation and those for the linear formulation of the s-PTT model. The comparison shows that results for linear formulation deviate significantly from those for exponential formulation and thus the accuracy of the exponential formulation justifies the extra mathematical complexity which it entails.

  2. Tick resistance and heat tolerance characteristics in cattle. III. Sweating rate

    Directory of Open Access Journals (Sweden)

    Cecília José Veríssimo

    2012-12-01

    Full Text Available Cattle in a sustainable tropical livestock should be heat tolerant and resistant to ticks. The relationship between Rhipicephalus (Boophilus microplus infestation and sweating rate, an important heat tolerance characteristic, was studied in six Nellore and four Holstein steers of seven-month-old. They were artificial infested (a.i. with 10,000 (Holstein and 20,000 (Nellore larvae in 16/Apr/2011. In days 20, 23 and 24 after the infestation, the 10 bigger females ticks found in whole animal were weighed and put in a chamber (27 oC and 80% RH, weighing the egg mass of each female tick fourteen days after. The sweating rate (SRskin, measured by Scheleger and Turner, 1963, method, in a shaved area of shoulder skin was evaluated in 14/Apr (2 days before the a.i. and in 05/May (19 days after a.i.. In 14/Apr the Scheleger and Turner, 1963, method was done on the coat not shaved (SRcoat. The sweating rate was measured in the afternoon (from 2 P.M., after 30 minutes of direct sunlight, on April. On May, the animals remained 60 minutes in direct sunlight because this day was colder. The experimental design was a non-probability sample restricted to the 10 available animals. Data from the steers’ sweating rate were analyzed using the General linear models of the SPSS® statistical package (version 12.0 using SRskin as dependent variable and breed and sampling date as independent variables. For SRcoat breed was the independent variable. Nellore, a tropical cattle breed, had higher SRskin (1,000.82 ± 64.59 g m-2 h-1, P< 0.001 than Holstein (620.45 ± 79.10 g m-2 h-1. SRskin was higher on May (1,187.33 ± 71.49 g m-2 h-1, P< 0.001 than on April (433.93 ± 71.49 g m-2 h-1. The correlation between the two different measurements of SR was positive and significant (r= 0,545, P<0,01, Pearson correlation. But in SRcoat the breed effect disappeared because the Holstein SRcoat increased (Holstein: 884.95 ± 472.12 g m-2 h-1 and Nellore: 1,060.72 ± 318.21 g m-2 h-1

  3. Algorithms and programs for solution of static and dynamic characteristics of counterflow heat exchangers with dissociating coolant

    International Nuclear Information System (INIS)

    Nitej, N.V.; Sharovarov, G.A.

    1982-01-01

    The method of estimation of counterflow heat exchanger characteristics is presented. Mathematical description of the processes is presented by the mass, energy and pulse conservation equations for both coolants and energy conservation equation for the wall which devides them. In the presence of chemical reactions the system is supplemented by equations, characterizing the kinetics of their progress. The methods of numerical solution of static and dynamic problems have been chosen, and the computer programs on the Fortran language have been developed. The schemes of solution of both problems are so constructed, that the conservation equations are placed in the main program, and such characteristics of the coolants as properties, heat transfer and friction coefficients, the mechanism of chemical reaction are concentrated in the subprogram unit. This allows to create the single method of solution with the flow of single-phase and two-phase coolants of abovecritical and supercritical paramters. The evaluation results of three heat exchangers are given: with heating of N 2 O 4 gas phase by heat of flue gas; with cooling of N 2 O 4 supercritical parameters by water; regenerator on N 2 O 4

  4. Influence of Microstructure and Composition Changes on Mechanical Characteristics of Aluminium Alloy After Heating and Cooling Treatment

    International Nuclear Information System (INIS)

    Sigit; Nuraini, E; Martoyo

    1998-01-01

    Influences of microstructure and chemical composition changes on mechanical characteristics of AIMg2 which were heated at 85-500 0 C and cooled with sands, water or air have been studied. Microstructure observation was carried out using optical microscope, while chemical composition determination by atomic absorption spectrophotometry (AAS). AIMg2 which has been heated at the relatively low temperature i. e, 200 0 C during 6 hours and cooled using sands showed a small change microstructure, but those will be clearly observed on the treatment at 300 0 C. The microstructure change is in agreement with the change of mechanical characteristic, I. e., the decreasing of tensile strength and hardness and increasing of elongation. After the temperature of treatment is higher than 300 0 C, the decreasing of the tensile strength was relatively constant, while the hardness increased. The microstructure of AIMg2 resulted from the heat treatment at temperature of 500 0 C was different with that of 300 0 C. Heat treatment at 500 0 C following by cooling in the sands, water or air respectively gave similar microstructure. Those also caused the change of alloying element content which was in agreement with decreasing of mechanical characteristics

  5. The Characteristic of Molten Heat Salt Storage System Utilizing Solar Energy Combined with Valley Electric

    Directory of Open Access Journals (Sweden)

    LI .Jiu-ru

    2017-02-01

    Full Text Available With the environmental pollution and energy consumption clue to the large difference between peak and valley of power grid,the molten salt heat storage system(MSHSS utilizing solar Energy combined with valley electric is presented for good energy saving and low emissions. The costs of MSHSS utilizing solar Energy combined with valley electric are greatly reduced. The law of heat transfer in molten salt heat storage technology is studied with the method of grey correlation analysis. The results show the effect of elbow sizes on surface convective heat transfer coefficient with different flow velocities.

  6. Prototype Vent Gas Heat Exchanger for Exploration EVA - Performance and Manufacturing Characteristics

    Science.gov (United States)

    Quinn, Gregory J.; Strange, Jeremy; Jennings, Mallory

    2013-01-01

    NASA is developing new portable life support system (PLSS) technologies, which it is demonstrating in an unmanned ground based prototype unit called PLSS 2.0. One set of technologies within the PLSS provides suitable ventilation to an astronaut while on an EVA. A new component within the ventilation gas loop is a liquid-to-gas heat exchanger to transfer excess heat from the gas to the thermal control system s liquid coolant loop. A unique bench top prototype heat exchanger was built and tested for use in PLSS 2.0. The heat exchanger was designed as a counter-flow, compact plate fin type using stainless steel. Its design was based on previous compact heat exchangers manufactured by United Technologies Aerospace Systems (UTAS), but was half the size of any previous heat exchanger model and one third the size of previous liquid-to-gas heat exchangers. The prototype heat exchanger was less than 40 cubic inches and weighed 2.57 lb. Performance of the heat exchanger met the requirements and the model predictions. The water side and gas side pressure drops were less 0.8 psid and 0.5 inches of water, respectively, and an effectiveness of 94% was measured at the nominal air side pressure of 4.1 psia.

  7. Thermal Characteristics of an Oscillating Heat Pipe Cooling System for Electric Vehicle Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Ri-Guang Chi

    2018-03-01

    Full Text Available The heat generation of lithium ion batteries in electric vehicles (EVs leads to a degradation of energy capacity and lifetime. To solve this problem, a new cooling concept using an oscillating heat pipe (OHP is proposed. In the present study, an OHP has been adopted for Li-ion battery cooling. Due to the limited space in EVs, the cooling channel is installed on the bottom of the battery module. In the bottom cooling method with an OHP, generated heat can be dissipated easily and conveniently. However, most studies on heat pipes have used bottom heating and top or side cooling methods, so we investigate the various effects of parameters with a top heating/bottom cooling mode with the OHP, i.e., the inclination angle of the system, amount of working fluid charged, the heating amount, and the cold plate temperature with ethanol as a working fluid. The experimental results show that the thermal resistance (0.6 °C/W and uneven pulsating features influence the heat transfer performance. A heater used as a simulated battery was sustained under 60 °C under 10 W and 14 W heating conditions. This indicates that the proposed cooling system with the bottom cooling is feasible for use as an EV’s battery cooling system.

  8. Frosting characteristics and heating performance of a direct-expansion solar-assisted heat pump for space heating under frosting conditions

    International Nuclear Information System (INIS)

    Huang, Wenzhu; Ji, Jie; Xu, Ning; Li, Guiqiang

    2016-01-01

    Highlights: • Frosting and heating performance of DX-SAHP under frosting conditions is investigated. • The conditions when DX-SAHP frosts are studied. • The frosting process is observed during 360 min of operating. • The effect of ambient temperature, relative humidity and solar irradiation is analyzed. - Abstract: Direct expansion solar-assisted heat pump system (DX-SAHP) is promising in energy saving applications, but the performance of DX-SAHP under frosting conditions is rarely reported in the published literatures. In this paper, a DX-SAHP system with bare solar collectors for space heating is designed and experimentally investigated in the enthalpy difference lab with a solar simulator. The system is tested under a range of frosting conditions, with the ambient temperatures from 7 °C to −3 °C, the relative humidities of 50%, 70% and 90% and the solar irradiances of 0 W/m"2, 100 W/m"2, 200 W/m"2 and 300 W/m"2. The conditions when the DX-SAHP system frosts are studied. Results show that solar irradiance as low as 100 W/m"2 can totally prevent frosting when the ambient temperature is above −3 °C and the relative humidity is 70%. Besides, the frosting process is observed to be slower than that of fin-and-tube heat exchangers. The evaporator is not seriously frosted and the system performance is not significantly influenced after 360 min of continuous operating. Moreover the effects of ambient parameters, including the ambient temperature and the relative humidity, especially solar irradiation, on the system performance are studied and analyzed. Solar irradiation can effectively prevent or retard frosting, and also improve the heating performance of the DX-SAHP system. The DX-SAHP system is proved to be applicable under frosting conditions.

  9. Study on characteristic differences of wheat 1Ax1 and 1Ax2* NILS obtained by transgenic HMW-GS 1Dx5 + 1Dy10 gene

    International Nuclear Information System (INIS)

    Sun Yan; Zhang Hongji; Liu Dongjun; Qi Qianqian; Yang Shuping; Guo Yipan; Ma Shumei; Liu Wenlin; Wang Guangjin; Zhao Wei

    2012-01-01

    Use wheat 1Ax1 and 1Ax2* NILS obtained by transgenic HMW-GS 1Dx5 + 1Dy10 gene, characteristics differences have been studied. The two-year results showed that the statistical differences in seed quality parameters, farinogram parameters, extensigram parameters, botany characters and main agricultural characters between 1Ax1 and 1Ax2* were not significant. We considered that 08K860 and 08K871 are similar in hereditary background, 1Ax1 and 1Ax2* have identical contribute on quality. Breeder should attach to 1Ax1 and 1Ax2* identically on wheat breeding. (authors)

  10. Study on characteristic differences of wheat 1Ax1 and 1Ax2* NILS obtained by transgenic HMW-GS 1Dx5+1Dy10 gene

    International Nuclear Information System (INIS)

    Sun Yan; Zhang Hongji; Liu Dongjun; Qi Qianqian; Yang Shuping; Guo Yifan; Ma Shumei; Liu Wenlin; Wang Guangjin; Zhao Wei

    2011-01-01

    Use wheat 1Ax1 and 1Ax2 * NILS obtained by transgenic HMW-GS 1Dx5+1Dy10 gene, characteristics differences have been studied. The two-year results showed that the statistical differences in seed quality parameters, farinogram parameters, extensigram parameters, botany characters and main agricultural characters between 1Ax1 and 1Ax2 * were not significant. We considered that 08K860 and 08K871 are similar in hereditary background, 1Ax1 and 1Ax2 * have identical contribute on quality. Breeder should atlach to 1Ax1 and 1Ax2 * identically on wheat breeding. (authors)

  11. LavaSIM: the effect of heat transfer in 3D on lava flow characteristics (Invited)

    Science.gov (United States)

    Fujita, E.

    2013-12-01

    Characteristics of lava flow are governed by many parameters like lava viscosity, effusion rate, ground topography, etc. The accuracy and applicability of lava flow simulation code is evaluated whether the numerical simulation can reproduce these features quantitatively, which is important from both strategic and scientific points of views. Many lava flow simulation codes are so far proposed, and they are classified into two categories, i.e., the deterministic and the probabilistic models. LavaSIM is one of the former category models, and has a disadvantage of time consuming. But LavaSIM can solves the equations of continuity, motion, energy by step and has an advantage in the calculation of three-dimensional analysis with solid-liquid two phase flow, including the heat transfer between lava, solidified crust, air, water and ground, and three-dimensional convection in liquid lava. In other word, we can check the detailed structure of lava flow by LavaSIM. Therefore, this code can produce both channeled and fan-dispersive flows. The margin of the flow is solidified by cooling and these solidified crusts control the behavior of successive lava flow. In case of a channel flow, the solidified margin supports the stable central main flow and elongates the lava flow distance. The cross section of lava flow shows that the liquid lava flows between solidified crusts. As for the lava extrusion flow rate, LavaSIM can include the time function as well as the location of the vents. In some cases, some parts of the solidified wall may be broken by the pressure of successive flow and/or re-melting. These mechanisms could characterize complex features of the observed lava flows at many volcanoes in the world. To apply LavaSIM to the benchmark tests organized by V-hub is important to improve the lava flow evaluation technique.

  12. Discovery of an 'internal heating effect' during electrochemical etching of polymeric dosimeters: a study of polymer characteristics

    International Nuclear Information System (INIS)

    Sohrabi, M.

    1986-01-01

    This paper investigates the importance of the internal heating effect by studying the role of different polymer physical and chemical characteristics (composition, effective foil size, thickness and electrical properties), on the rate of heating or temperature rise responses for cellulose tri-acetate (CTA), cellulose acetate (CA), allyl diglycol carbonate (CR-39), cellulose nitrate (CN), cellulose acetate butyrate (CAB), polyester (PES), polycarbonate (PC) and polyethylene (PE). Efforts have been made to justify the observed effects by different mechanisms such as dielectric loss, electro-osmosis, dielectrophoresis, and electrostriction. (author)

  13. The effects of cold rolling and the subsequent heat treatments on the shape memory and the superelasticity characteristics of Cu73Al16Mn11 shape memory alloy

    Science.gov (United States)

    Babacan, N.; Ma, J.; Turkbas, O. S.; Karaman, I.; Kockar, B.

    2018-01-01

    In the present study, the effect of thermo-mechanical treatments on the shape memory and the superelastic characteristics of Cu73Al16Mn11 (at%) shape memory alloy were investigated. 10%, 50% and 70% cold rolling and subsequent heat treatment processes were conducted to achieve strengthening via grain size refinement. 70% grain size reduction compared to the homogenized condition was obtained using 70% cold rolling and subsequent recrystallization heat treatment technique. Moreover, 10% cold rolling was applied to homogenized specimen to reveal the influence of the low percentage cold rolling reduction with no heat treatment on shape memory properties of Cu73Al16Mn11 (at%) alloy. Stress free transformation temperatures, monotonic tension and superelasticity behaviors of these samples were compared with those of the as-aged sample. Isobaric heating-cooling experiments were also conducted to see the dimensional stability of the samples as a function of applied stress. The 70% grain-refined sample exhibited better dimensional stability showing reduced residual strain levels upon thermal cycling under constant stress compared with the as-aged material. However, no improvement was achieved with grain size reduction in the superelasticity experiments. This distinctive observation was attributed to the difference in the magnitude of the stress levels achieved during two different types of experiments which were the isobaric heating-cooling and superelasticity tests. Intergranular fracture due to the stress concentration overcame the strengthening effect via grain refinement in the superelasticity tests at higher stress values. On the other hand, the strength of the material and resistance of material against plastic deformation upon phase transformation were increased as a result of the grain refinement at lower stress values in the isobaric heating-cooling experiments.

  14. Effects of physical parameters on the heat and mass transfer characteristics in freeze-drying processes of fruits and vegetables

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yuming; Liu, Lijuan; Liang, Li [Shanxi Agricultural Univ. (China). Coll. of Engineering and Technology], E-mail: guoyuming99@sina.com

    2008-07-01

    Studying the effects mechanism of material physical parameters on the heat and mass transfer characteristics, the process parameters and energy consumption during freeze-drying process is of importance in improving the vacuum freeze-drying process with low energy consumption. In this paper, the sliced and mashed carrots of one variety were selected to perform the vacuum freeze-drying experiments. First, the variation laws of surface temperatures and sublimation front temperatures of the two shapes samples during the freeze-drying processes were analyzed, and it was verified that the process of sliced carrots is controlled by mass transfer, while that of the mashed ones is heat-transfer control. Second, the variations of water loss rate, energy consumption and temperature of the two shapes samples under the appropriate heating plate temperature and the different drying chamber pressure were analyzed. In addition, the effects of thermal conductivity and thermal diffusivity on freeze-drying time and process parameters were discussed by utilizing the theory of heat and mass transfer. In conclusion, under the heat transfer condition, the temperature of the heating plate should be as high as possible within the permitted range, and the drying chamber pressure should be set at optimal level. While under the mass transport-limited condition, the pressure level need to be altered in short time. (author)

  15. Effect of heat treatment to sweet potato flour on dough properties and characteristics of sweet potato-wheat bread.

    Science.gov (United States)

    Pérez, Isela Carballo; Mu, Tai-Hua; Zhang, Miao; Ji, Lei-Lei

    2017-12-01

    The effect of heat treatment at 90, 100, 110 and 120 ℃ for 20 min to sweet potato flour on dough properties and characteristics of sweet potato-wheat bread was investigated. The lightness (L*) and a* of sweet potato flour samples after heat treatment were increased, while the b* were decreased significantly, as well as the particle size, volume and area mean diameter ( p sweet potato flour was observed, where the number of irregular granules increased as the temperature increased from 90 to 120 ℃. Compared with sweet potato flour samples without heat treatment and with heat treatment at 90, 100 and 120 ℃, the gelatinization temperature and enthalpy change of sweet potato flour at 110 ℃ were the lowest, which were 77.94 ℃ and 3.67 J/g, respectively ( p sweet potato flour increased significantly from 1199 ml without heat treatment to 1214 ml at 90 ℃ ( p sweet potato-wheat bread with sweet potato flour after heat treatment increased significantly, which was the largest at 90 ℃ (2.53 cm 3 /g) ( p sweet potato flour could be potentially used in wheat bread production.

  16. [Characteristics of CO2 flux before and in the heating period at urban complex underlying surface area].

    Science.gov (United States)

    Jia, Qing-yu; Zhou, Guang-sheng; Wang, Yu; Liu, Xiao-mei

    2010-04-01

    Urban areas were significant contributors to global carbon dioxide emissions. The eddy covariance (EC) was used to measure carbon dioxide (CO2) concentration and flux data at urban area in Shenyang. This research analyzed the characteristics of atmospheric CO2 concentration and flux in October 2008 to November 2008 period before and in the heating period. The results showed that the daily variation of CO2 concentration was two-peak curve. The first peak time appeared as same as sunrise time, while the second peak time impacted by vehicles and heating. The result of CO2 flux showed that urban atmospheric CO2 was net emissions, vegetation photosynthesis absorbed CO2 of traffic, the CO2 flux peak appeared at 17:15-18:15 in the heating period, CO2 emission increased 29.37 g x (m2 x d)(-1) in the heating period than that before the heating period; there was corresponding relationship between CO2 flux and the time when temperature peak and sensible heating flux (Hc) turn positive. The results also indicated that atmospheric CO2 concentration and its flux were affected seriously by both wind direction and carbon sources.

  17. Effect of heat treatment on the characteristics of tool steel deposited by the directed energy deposition process

    Science.gov (United States)

    Park, Jun Seok; Lee, Min-Gyu; Cho, Yong-Jae; Sung, Ji Hyun; Jeong, Myeong-Sik; Lee, Sang-Kon; Choi, Yong-Jin; Kim, Da Hye

    2016-01-01

    The directed energy deposition process has been mainly applied to re-work and the restoration of damaged steel. Differences in material properties between the base and the newly deposited materials are unavoidable, which may affect the mechanical properties and durability of the part. We investigated the effect of heat treatment on the characteristics of tool steel deposited by the DED process. We prepared general tool steel materials of H13 and D2 that were deposited onto heat-treated substrates of H13 and D2, respectively, using a direct metal tooling process. The hardness and microstructure of the deposited steel before and after heat treatment were investigated. The hardness of the deposited H13 steel was higher than that of wrought H13 steel substrate, while that of the deposited D2 was lower than that of wrought D2. The evolution of the microstructures by deposition and heat treatment varied depending on the materials. In particular, the microstructure of the deposited D2 steel after heat treatment consisted of fine carbides in tempered martensite and it is expected that the deposited D2 steel will have isotropic properties and high hardness after heat treatment.

  18. Melting and solidification characteristics of a mixture of two types of latent heat storage material in a vessel

    Science.gov (United States)

    Yu, JikSu; Horibe, Akihiko; Haruki, Naoto; Machida, Akito; Kato, Masashi

    2016-11-01

    In this study, we investigated the fundamental melting and solidification characteristics of mannitol, erythritol, and their mixture (70 % by mass mannitol: 30 % by mass erythritol) as potential phase-change materials (PCMs) for latent heat thermal energy storage systems, specifically those pertaining to industrial waste heat, having temperatures in the range of 100-250 °C. The melting point of erythritol and mannitol, the melting peak temperature of their mixture, and latent heat were measured using differential scanning calorimetry. The thermal performance of the mannitol mixture was determined during melting and solidification processes, using a heat storage vessel with a pipe heat exchanger. Our results indicated phase-change (fusion) temperatures of 160 °C for mannitol and 113 and 150 °C for the mannitol mixture. Nondimensional correlation equations of the average heat transfer during the solidification process, as well as the temperature and velocity efficiencies of flowing silicon oil in the pipe and the phase-change material (PCM), were derived using several nondimensional parameters.

  19. The role of hybrid nanofluids in improving the thermal characteristics of screen mesh cylindrical heat pipes

    Directory of Open Access Journals (Sweden)

    Ramachandran Raghavan Nair

    2016-01-01

    Full Text Available Experiments were conducted to study the thermal performance of meshed wick heat pipe by varying the working fluid and heat input. In this work four screen mesh wicked heat pipes were fabricated and tested. All the heat pipes were tested for heat input from 50W to 250W each with an increment of 50W in each step. The heat input range selected in this study is commonly encountered in most of the electronic application devices. The thermal resistance of all the heat pipes charged with different working fluids such as DI water, Al2O3/DI water nanofluid of volume concentration 0.1 % and hybrid nanofluid volume concentration 0.1%( with two different combinations of (Al2O3 50%- CuO 50%/DI water and (Al2O3 25%- CuO 75%/DI waterwas determined. The maximum percentage reduction was found to be 58.87% for the hybrid nanofluid of (Al2O3 25%- CuO 75%/DI water compared to base fluid. An important observation from the study is that, use of hybrid nanofluid can raise the operating range of the heat pipe beyond 250W which makes hybrid nanofluid as a potential substitute for the conventional working fluid.

  20. Determination of thermal characteristics of combustion products of fire-tube heat generator with flow turbulator

    Directory of Open Access Journals (Sweden)

    Lukjanov Alexander V.

    2014-12-01

    Full Text Available Boiler construction is one of the major industries of any state. The aim is to determine the effect of the turbulator on the intensity of heat transfer in the convective part of the fire-tube heat generator of domestic production. The improvement of convective heating surfaces is one of the ways to increase the energy efficiency of the fire-tube heat generator. Since model of the process of heat transfer of gas flow in the convective tubes is multifactorial and does not have clear analytical solution at present, the study of process above is carried out using the experimental method. The results of applying the flow turbulator as a broken tape in the fire-tube heat generator of KV-GM type are presented. On their basis it can be concluded about increasing of heat transfer in convective part of the unit. The use of efficient, reliable, easy to manufacture, relatively inexpensive turbulator in domestic fire-tube heat generators will allow to increase their energy conversion efficiency and reduce fuel consumption, which will have a positive economic effect.

  1. Experimental study on the effects of channel gap size on mixed convection heat transfer characteristics in vertical rectangular channels heated from both sides

    International Nuclear Information System (INIS)

    Sudo, Y.; Kaminaga, M.

    1990-01-01

    The effects of channel gap size on mixed forced and free convective heat transfer characteristics were experimentally investigated for water flowing near atmospheric pressure in a 750 mm long and 50 mm wide channel heated from both sides. The channel gap sizes investigated were 2.5, 6, 18 and 50 mm. Experiments were carried out for both aiding and opposing forced convective flows with a Reynolds number Re x of 4x10 to 6x10 6 and a Grashof number Gr x of 2x10 4 to 6x10 11 , where the distance x from the inlet of the channel is adopted as the characteristic length in Re x and Gr x . As for the results, the following were revealed for the parameters ranges investigated in this study. (1) When the dimensionless parameter, Gr x /Re x 21/8 Pr 1/2 is less than 10 -4 , the flow shows the nature of forced convective heat transfer for a channel with any channel gap size in both aiding and opposing flows. (2) When Gr x /Re x 21/8 Pr 1/2 is larger than 10 -2 , the flow shows the nature of free convective heat transfer for a channel with any channel gap size in both aiding and opposing flows. (3) When Gr x /Re x 21/8 Pr 1/2 is between 10 -4 and 10 -2 for the channel with a channel gap size equal to or larger than 6 mm, the heat transfer coefficients in both aiding and opposing flows become, on the average, higher than those predicted by the previous correlations for either the pure turbulent forced convection or the pure free convection, and can be expressed in simple forms with a combination of Gr x /Re x 21/8 Pr 1/2 and the previous correlation for either the pure turbulent forced convection or the free convection along a flat plate. (4) When Gr x /Re x 21/8 Pr 1/2 is between 10 -4 and 10 -2 for the channel with a channel gap size of 2.5 mm, the heat transfer coefficients in both aiding and opposing flows also become, on the average, higher than those predicted by the previous correlations for either the pure turbulent forced convection or the pure free convection. (orig./GL)

  2. Base Flow and Heat Transfer Characteristics of a Four-Nozzle Clustered Rocket Engine: Effect of Nozzle Pressure Ratio

    Science.gov (United States)

    Nallasamy, R.; Kandula, M.; Duncil, L.; Schallhorn, P.

    2010-01-01

    The base pressure and heating characteristics of a four-nozzle clustered rocket configuration is studied numerically with the aid of OVERFLOW Navier-Stokes code. A pressure ratio (chamber pressure to freestream static pressure) range of 990 to 5,920 and a freestream Mach number range of 2.5 to 3.5 are studied. The qualitative trends of decreasing base pressure with increasing pressure ratio and increasing base heat flux with increasing pressure ratio are correctly predicted. However, the predictions for base pressure and base heat flux show deviations from the wind tunnel data. The differences in absolute values between the computation and the data are attributed to factors such as perfect gas (thermally and calorically perfect) assumption, turbulence model inaccuracies in the simulation, and lack of grid adaptation.

  3. Studies on cycle characteristics and application of split heat pipe adsorption ice maker

    International Nuclear Information System (INIS)

    Chen, C.J.; Wang, R.Z.; Wang, L.W.; Lu, Z.S.

    2007-01-01

    A split heat pipe adsorption ice maker, which uses a solidified compound adsorbent (calcium chloride and activated carbon)-ammonia as working pair, is studied. The application of split heat pipe technology in this system (ice maker for fishing boat powered by waste heat of exhaust gases from diesel engine) solves the corrosion problem caused by using seawater to cool the adsorber directly. Therefore, the adsorbers can be cooled or heated by the working substance of the heat pipe in the adsorption or desorption state, respectively. There are two adsorbers in the adsorption ice maker, and each adsorber contains 2.35 kg compound adsorbent in which the mass of calcium chloride is 1.88 kg. The mass transfer performance and volume cooling density of the chemical adsorbent are greatly improved by the use of the compound adsorbent. Water is chosen as the working substance of the heat pipe due to its high cooling power in comparison with the experiments performed using acetone as working substance. When the cycle time is 70 min, the average SCP of ice making is about 329.8-712.8 W/kg calcium chloride with heat and mass recovery, which is approximately 1.6-3.5 times that of the best results of a conventional chemical adsorption ice maker

  4. Heat Transfer Characteristics for an Upward Flowing Supercritical Pressure CO{sub 2} in a Vertical Circular Tube

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Deog Ji

    2008-02-15

    The SCWR(Super Critical Water-cooled Reactor) is one of the feasible options for the 4th generation nuclear power plant, which is being pursued by an international collaborative organization, the Gen IV International Forum(GIF). The major advantages of the SCWR include a high thermal efficiency and a maximum use of the existing technologies. In the SCWR, the coolant(water) of a supercritical pressure passes the pseudo-critical temperature as it flows upward through the sub-channels of the fuel assemblies. At certain conditions a heat transfer deterioration occurs near the pseudo-critical temperature and it may cause an excessive rise of the fuel surface temperature. Therefore, an accurate estimation of the heat transfer coefficient is necessary for the thermal-hydraulic design of the reactor core. A test facility, SPHINX(Supercritical Pressure Heat Transfer Investigation for the Next Generation), dedicated to produce heat transfer data and study flow characteristics, uses supercritical pressure CO{sub 2} as a surrogate medium to take advantage of the relatively low critical temperature and pressure: and similar physical properties with water. The produced data includes the temperature of the heating surface and the heat transfer coefficient at varying mass fluxes, heat fluxes, and operating pressures. The test section is a circular tube of ID 6.32 mm: it is almost the same as the hydraulic diameter of the sub-channel in the conceptional design presented by KAERI. The test range of the mass flux is 285 to 1200 kg/m{sup 2}s and the maximum heat flux is 170 kW/m{sup 2}. The tests were mainly performed for an inlet pressure of 8.12 MPa which is 1.1 times of critical pressure. With the test results of the wall temperature and the heat transfer coefficient, effects of mass flux, heat flux, inlet pressure, and the tube diameter on the heat transfer were studied. And the test results were compared with the existing correlations of the Nusselt number. In addition, New

  5. Heat flux characteristics in an atmospheric double arc argon plasma jet

    International Nuclear Information System (INIS)

    Tu Xin; Yu Liang; Yan Jianhua; Cen Kefa; Cheron, Bruno

    2008-01-01

    In this study, the axial evolution of heat flux excited by a double arc argon plasma jet impinging on a flat plate is determined, while the nonstationary behavior of the heat flux is investigated by combined means of the fast Fourier transform, Wigner distribution, and short-time Fourier transform. Two frequency groups (<1 and 2-10 kHz) are identified in both the Fourier spectrum and the time-frequency distributions, which suggest that the nature of fluctuations in the heat flux is strongly associated with the dynamic behavior of the plasma arc and the engulfment of ambient air into different plasma jet regions

  6. Influence of the external heating type in the morphological and structural characteristics of alumina powder prepared by combustion reaction

    International Nuclear Information System (INIS)

    Cordeiro, V.V.; Freitas, N.L.; Viana, K.M.S.; Dias, G.; Costa, A.C.F.M.; Lira, H.L.

    2009-01-01

    The aim of this work is to evaluate the influence of the external heating in the morphological and structural characteristics of the alumina powder prepared by combustion reaction. It was evaluated different types of external heating: muffle oven, microwave oven and ceramic plate with electrical spiral resistance. The powders were prepared according to the propellants and explosives theory, using urea in the stoichiometric proportion (Φe = 1). During the synthesis parameters such as flame combustion time and temperature were measured. The structural and morphological characteristics of the powders were evaluate by XRD, particle size distribution, SEM and nitrogen adsorption (BET). The results showed the production of a-alumina as unique phase and formed by agglomerates with irregular plate shape of thin particles for all studied conditions. The powders prepared by electrical oven presented small particle size, with narrow agglomerates size distribution. (author)

  7. The influence of target and patient characteristics on the volume obtained from cone beam CT in lung stereotactic body radiation therapy

    International Nuclear Information System (INIS)

    Liu, Hong-Wei; Khan, Rao; D’Ambrosi, Rafael; Krobutschek, Krista; Nugent, Zoann; Lau, Harold

    2013-01-01

    Purpose: To investigate the influence of tumor and patient characteristics on the target volume obtained from cone beam CT (CBCT) in lung stereotactic body radiation therapy (SBRT). Materials and methods: For a given cohort of 71 patients, the internal target volume (ITV) in CBCT obtained from four different datasets was compared with a reference ITV drawn on a four-dimensional CT (4DCT). The significance of the tumor size, location, relative target motion (RM) and patient’s body mass index (BMI) and gender on the adequacy of ITV obtained from CBCT was determined. Results: The median ITV-CBCT was found to be smaller than the ITV-4DCT by 11.8% (range: −49.8 to +24.3%, P < 0.001). Small tumors located in the lower lung were found to have a larger RM than large tumors in the upper lung. Tumors located near the central lung had high CT background which reduced the target contrast near the edges. Tumor location close to center vs. periphery was the only significant factor (P = 0.046) causing underestimation of ITV in CBCT, rather than RM (P = 0.323) and other factors. Conclusions: The current clinical study has identified that the location of tumor is a major source of discrepancy between ITV-CBCT and ITV-4DCT for lung SBRT

  8. Characteristics of Vacuum Freeze Drying with Utilization of Internal Cooling and Condenser Waste Heat for Sublimation

    Directory of Open Access Journals (Sweden)

    Muhammad Alhamid

    2013-09-01

    Full Text Available Vacuum freeze drying is an excellent drying method, but it is very energy-intensive because a relatively long drying time is required. This research investigates the utilization of condenser waste heat for sublimation as a way of accelerating the drying rate. In addition, it also investigates the effect of internal cooling combined with vacuum cooling in the pressure reduction process. Jelly fish tentacles were used as the specimen, with different configurations for condenser heat waste and internal cooling valve opening. The results show that heating with condenser heat waste can accelerate the drying rate up to 0.0035 kg/m2.s. In addition, pre-freezing by internal cooling prevents evaporation until the mass of the specimen is 0.47 g and promotes transition of the specimen into the solid phase.

  9. Study of natural convection heat transfer characteristics. (2) Verification for numerical simulation

    International Nuclear Information System (INIS)

    Ikeda, Hiroshi; Nakada, Kotaro; Ikeda, Tatsumi; Wakamatsu, Mitsuo; Iwaki, Chikako; Morooka, Shinichi; Masaki, Yoshikazu

    2008-01-01

    In the natural cooling system for waste storage, it is important to evaluate the flow by natural draft enough to remove the decay heat from the waste. In this study, we carried out the fundamental study of natural convection on vertical cylindrical heater by experiment and numerical simulation. The dimension of test facility is about 4m heights with single heater. Heating power is varied in the range of 33-110W, where Rayleigh number is over 10 10 . We surveyed the velocity distribution around heater by some turbulent models, mesh sizes around heated wall and turbulent Prandtl numbers. Results of numerical simulation of the velocity distribution and averaged heat transfer coefficient agreed well with experimental data and references. (author)

  10. Study of integral characteristics and efficiency of a heat exchanger of thermosyphon type with finned tubes

    Directory of Open Access Journals (Sweden)

    Iliev Iliya K.

    2016-01-01

    Full Text Available The experimental research aims at the analysis of the thermal performance of a gas-liquid heat exchanger in a pilot plant. Results of the conducted experiment with a finned tubes thermosyphon heat exchanger using natural gas are presented. The installation was mounted at the exit of a flue gas from an existing steam generator “PK-4” with total power of 2.88 MW in the boiler room of Vini, Sliven, Bulgaria. Different experiments were carried out at different loads of the steam generator in order to determine the efficiency of the heat exchanger. Based on these results the coefficient of heat transfer of flue gas to the finned tubes was determined, based on different modes of operation with crossed and straight pipe bundles. The effectiveness-number of transfer units method was used.

  11. Characteristics of turbulent velocity and temperature in a wall channel of a heated rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, T.; Meyer, L. [Forschungszentrum Karlsruhe (Germany)

    1995-09-01

    Turbulent air flow in a wall sub-channel of a heated 37-rod bundle (P/D = 1.12, W/D = 1.06) was investigated. measurements were performed with hot-wire probe with X-wires and a temperature wire. The mean velocity, the mean fluid temperature, the wall shear stress and wall temperature, the turbulent quantities such as the turbulent kinetic energy, the Reynolds-stresses and the turbulent heat fluxes were measured and are discussed with respect to data from isothermal flow in a wall channel and heated flow in a central channel of the same rod bundle. Also, data on the power spectral densities of the velocity and temperature fluctuations are presented. These data show the existence of large scale periodic fluctuations are responsible for the high intersubchannel heat and momentum exchange.

  12. Conduction and convection heat transfer characteristics of water-based au nanofluids in a square cavity with differentially heated side walls subjected to constant temperatures

    Directory of Open Access Journals (Sweden)

    Ternik Primož

    2014-01-01

    Full Text Available The present work deals with the natural convection in a square cavity filled with the water-based Au nanofluid. The cavity is heated on the vertical and cooled from the adjacent wall, while the other two horizontal walls are adiabatic. The governing differential equations have been solved by the standard finite volume method and the hydrodynamic and thermal fields were coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of the nanoparticles’ volume fraction on the heat transfer characteristics of Au nanofluids at the given base fluid’s (i.e. water Rayleigh number. Accurate results are presented over a wide range of the base fluid Rayleigh number and the volume fraction of Au nanoparticles. It is shown that adding nanoparticles in a base fluid delays the onset of convection. Contrary to what is argued by many authors, we show by numerical simulations that the use of nanofluids can reduce the heat transfer rate instead of increasing it.

  13. Pressure drop and heat transfer characteristics for single-phase developing flow of water in rectangular microchannels

    International Nuclear Information System (INIS)

    Mirmanto; Kenning, D B R; Lewis, J S; Karayiannis, T G

    2012-01-01

    Experiments were conducted to investigate the pressure drop and heat transfer characteristics of single-phase flow of de-ionized water in single copper microchannels of hydraulic diameters 0.438 mm, 0.561 mm and 0.635 mm. The channel length was 62 mm. The experimental conditions covered a range of mass flux from 500 to 5000 kg/m 2 s in the laminar, transitional and low Reynolds number turbulent regimes. Pressure drop was measured for adiabatic flows with fluid inlet temperatures of 30°C, 60°C and 90°C. In the heat transfer tests, the heat flux ranged from 256 kW/m 2 to 519 kW/m 2 . Friction factors and Nusselt numbers determined from the measurements were higher than for fully-developed conditions, but in reasonable agreement with predictions made using published solutions for hydrodynamically and thermally developing flow. When entrance effects, experimental uncertainties, heat losses, inlet and exit losses, thermal boundary conditions and departure from laminar flow were considered, the results indicate that equations developed for flow and heat transfer in conventional size channels are applicable for water flows in microchannels of these sizes.

  14. The characteristics of heat flow in the Shenhu gas hydrate drilling area, northern South China Sea

    Science.gov (United States)

    Xu, Xing; Wan, Zhifeng; Wang, Xianqing; Sun, Yuefeng; Xia, Bin

    2016-12-01

    Marine heat flow is of great significance for the formation and occurrence of seabed oil, gas and gas hydrate resources. Geothermal gradient is an important parameter in determining the thickness of the hydrate stability zone. The northern slope of the South China Sea is rich in gas hydrate resources. Several borehole drilling attempts were successful in finding hydrates in the Shenhu area, while others were not. The failures demand further study on the distribution regularities of heat flow and its controlling effects on hydrate occurrence. In this study, forty-eight heat flow measurements are analyzed in the Shenhu gas hydrate drilling area, located in the northern South China Sea, together with their relationship to topography, sedimentary environment and tectonic setting. Canyons are well developed in the study area, caused mainly by the development of faults, faster sediment supply and slumping of the Pearl River Estuary since the late Miocene in the northern South China Sea. The heat flow values in grooves, occurring always in fault zones, are higher than those of ridges. Additionally, the heat flow values gradually increase from the inner fan, to the middle fan, to the external fan subfacies. The locations with low heat flow such as ridges, locations away from faults and the middle fan subfacies, are more conducive to gas hydrate occurrence.

  15. Heat transfer and pressure drop characteristics of mini-fin structures

    International Nuclear Information System (INIS)

    Jiang Peixue; Xu Ruina

    2007-01-01

    Forced convection heat transfer of air and water in bronze and pure copper mini-fin structures and mini-channel structures was investigated experimentally. The mini-fin dimensions were 0.7 mm x 0.2 mm and 0.8 mm x 0.4 mm. The tests included both staggered diamond-shaped and in-line square mini-fin arrangements. The tests investigated the effects of structures, mini-fin dimensions and arrangement, test section materials, and fluid properties on the convection heat transfer and heat transfer enhancement. For the tested conditions, the convection heat transfer coefficient was increased 9-21 fold for water and 12-38 fold for air in the mini-fin structures compared with an empty plate channel. The friction factor and flow resistance in the mini-channel structures and the in-line square mini-fin arrangement were much less than in the staggered diamond-shaped mini-fin arrangement. For the small channel width, W c = 0.2 mm, the convection heat transfer with the in-line square array structure was more intense than with the staggered diamond-shaped structure, the mini-channel structure or the porous media. For the larger channel width, W c = 0.4 mm, the convection heat transfer in the staggered diamond-shaped array structure was more intense than in the others systems while the in-line square structure had the best overall thermal-hydraulic performance

  16. Evaluation of the Characteristics of the Aluminum Alloy Casting Material by Heat Treatment

    International Nuclear Information System (INIS)

    Lee, Syung Yul; Park, Dong Hyun; Won, Jong Pil; Kim, Yun Hae; Lee, Myung Hoon; Moon, Kyung Man; Jeong, Jae Hyun

    2012-01-01

    Aluminum is on active metal, but it is well known that its oxide film plays a role as protective barrier which is comparatively stable in air and neutral aqueous solution. Thus, aluminum alloys have been widely applied in architectural trim, cold and hot-water storage vessels and piping etc., furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston because of its properties of temperature and wear resistance. In recent years, the oil price is getting higher and higher, thus the using of low quality oil has been significantly increased in engines of ship and vehicle. Therefore it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and prolong its lifetime. In this study, the effect of solution and tempering heat treatment to corrosion and wear resistance is investigated with electrochemical method and measurement of hardness. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment and exhibited the highest value of hardness with tempering heat treatment temperature at 190 .deg. C for 24hrs. Furthermore, corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. As a result, it is suggested that the optimum heat treatment to improve both corrosion and wear resistance is tempering heat treatment temperature at 190 .deg. C for 16hrs

  17. Performance Characteristics of PTC Elements for an Electric Vehicle Heating System

    Directory of Open Access Journals (Sweden)

    Yoon Hyuk Shin

    2016-10-01

    Full Text Available A high-voltage positive temperature coefficient (PTC heater has a simple structure and a swift response. Therefore, for cabin heating in electric vehicles (EVs, such heaters are used either on their own or with a heat pump system. In this study, the sintering process in the manufacturing of PTC elements for an EV heating system was improved to enhance surface uniformity. The electrode production process entailing thin-film sputtering deposition was applied to ensure the high heating performance of PTC elements and reduce the electrode thickness. The allowable voltage and surface heat temperature of the high-voltage PTC elements with thin-film electrodes were 800 V and 172 °C, respectively. The electrode layer thickness was uniform at approximately 3.8 μm or less, approximately 69% less electrode materials were required compared to that before process improvement. Furthermore, a heater for the EV heating system was manufactured using the developed high-voltage PTC elements to verify performance and reliability.

  18. On heat transfer characteristics of real and simulant melt pool experiments

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, T.N.; Nourgaliev R.R.; Sehgal, B.R. [Royal Institute of Technology, Stockholm (Sweden)

    1995-09-01

    The paper presents results of analytical studies of natural convection heat transfer in scaled and/or simulant melt pool experiments related to the PWR in-vessel melt retention issue. Specific reactor-scale effects of a large decay-heated core melt pool in the reactor pressure vessel lower plenum are first reviewed, and then the current analytical capability of describing physical processes under prototypical situations is examined. Experiments and experimental approaches are analysed by focusing on their ability to represent prototypical situations. Calculations are carried out in order to assess the significance of some selected effects, including variations in melt properties, pool geometry and heating conditions. Rayleigh numbers in the present analysis are limited to 10{sup 12}, where uncertainties in turbulence modeling are not overriding other uncertainties. The effects of fluid Prandtl number on heat transfer to the lowermost part of cooled pool walls are examined for square and semicircular cavities. Calculations are performed also to explore limitations of using side-wall heating and direct electrical heating in reproducing the physical picture of interest. Needs for further experimental and analytical efforts are discussed as well.

  19. Natural convection heat transfer characteristics of the molten metal pool with solidification by boiling coolant

    International Nuclear Information System (INIS)

    Cho, Jae Seon; Suh, Kune Yull; Chung, Chang Hyun; Park, Rae Joon; Kim, Sang Baik

    1997-01-01

    This paper presents results of experimental studies on the heat transfer and solidifcation of the molten metal pool with overlying coolant with boiling. The metal pool is heated from the bottom surface and coolant is injected onto the molten metal pool. As a result, the crust, which is a solidified layer, may form at the top of the molten metal pool. Heat transfer is accomplished by a conjugate mechanism, which consists of the natural convection of the molten metal pool, the conduction in the crust layer and the convective boiling heat transfer in the coolant. This work examines the crust formation and the heat transfer rate on the molten metal pool with boiling coolant. The simulant molten pool material is tin (Sn) with the melting temperature of 232 .deg. C. Demineralized water is used as the working coolant. The crust layer thickness was ostensibly varied by the heated bottom surface temperature of the test section, but not much affected by the coolant injection rate. The correlation between the Nusselt number and the Rayleight number in the molten metal pool region of this study is compared against the crust formation experiment without coolant boiling and the literature correlations. The present experimental results are higher than those from the experiment without coolant boiling, but show general agreement with the Eckert correlation, with some deviations in the high and low ends of the Rayleigh number. This discrepancy is currently attributed to concurrent rapid boiling of the coolant on top of the metal layer

  20. Thermal characteristic investigation of eutectic composite fatty acid as heat storage material for solar heating and cooling application

    Science.gov (United States)

    Thaib, R.; Fauzi, H.; Ong, H. C.; Rizal, S.; Mahlia, T. M. I.; Riza, M.

    2018-03-01

    A composite phase change material (CPCM) of myristic acid/palmitic acid/sodium myristate (MA/PA/SM) and of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) were impregnated with purified damar gum as called Shorea Javanica (SJ) to improve the thermal conductivity of CPCM. The thermal properties, thermal conductivity, and thermal stability of both CPCM have investigated by using a Differential Scanning Calorimetry (DSC) thermal analysis, hot disc thermal conductivity analyzer, and Simultaneous Thermal Analyzer (STA), simultaneously. However, a chemical compatibility between both fatty acid eutectic mixtures and SJ in composite mixtures measured by Fourier Transform Infra-Red (FT-IR) spectrophotometer. The results were obtained that the thermal conductivity of MA/PA/SM/SJ and MA/PA/SL/SJ eutectic composite phase change material (CPCM) were improved by addition 3 wt.% and 2 wt.% of Shorea javanica (SJ), respectively, without occur a significant change on thermal properties of CPCM. Moreover, the absorbance spectrum of FT-IR shows the good compatibility of SJ with both MA/PA/SM and MA/PA/SL eutectic mixtures, the composite PCM also present good thermal performance and good thermal stability. Therefore, it can be noted that the purified Shorea Javanica proposed, the as high conductive material in this study was able to improve the thermal conductivity of eutectic PCM without any significant reduction on its thermo-physical and chemical properties and can be recommended as novelty composite phase change material for thermal energy storage application.

  1. Dynamic characteristics of laser Doppler flowmetry signals obtained in response to a local and progressive pressure applied on diabetic and healthy subjects

    Science.gov (United States)

    Humeau, Anne; Koitka, Audrey; Abraham, Pierre; Saumet, Jean-Louis; L'Huillier, Jean-Pierre

    2004-09-01

    In the biomedical field, the laser Doppler flowmetry (LDF) technique is a non-invasive method to monitor skin perfusion. On the skin of healthy humans, LDF signals present a significant transient increase in response to a local and progressive pressure application. This vasodilatory reflex response may have important implications for cutaneous pathologies involved in various neurological diseases and in the pathophysiology of decubitus ulcers. The present work analyses the dynamic characteristics of these signals on young type 1 diabetic patients, and on healthy age-matched subjects. To obtain accurate dynamic characteristic values, a de-noising wavelet-based algorithm is first applied to LDF signals. All the de-noised signals are then normalised to the same value. The blood flow peak and the time to reach this peak are then calculated on each computed signal. The results show that a large vasodilation is present on signals of healthy subjects. The mean peak occurs at a pressure of 3.2 kPa approximately. However, a vasodilation of limited amplitude appears on type 1 diabetic patients. The maximum value is visualised, on the average, when the pressure is 1.1 kPa. The inability for diabetic patients to increase largely their cutaneous blood flow may bring explanations to foot ulcers.

  2. Experimental characteristics of ion Bernstein wave heating on JIPP T-IIU tokamak

    International Nuclear Information System (INIS)

    Ogawa, Y.; Kawahata, K.; Ando, R.

    1986-03-01

    The directly launched Ion Bernstein Wave (IBW) heating experiments have been carried out on JIPP T-IIU tokamak for two experimental conditions; (a) the ''3rd-branch'' of the IBW between 3rd- and 4th-cyclotron harmonics of the deuterium, and (b) the ''2nd-branch'' of the IBW between 2nd- and 3rd-cyclotron harmonics. In the case (a), the direct hydrogen heating at ω = 1.5 Ω H has been found in previous experiments. Here we present additional data to support this subharmonics heating, i.e., the spectroscopic measurement of Fe XVIII lines and mass separated analysis of charge-exchange neutrals. While, in the case (b), the remarkable increase of the electron temperature has been observed, especially at the central region of the plasma, and it has been estimated from the global energy balance that almost all of IBW power is delivered to the electron. To investigate this difference of the heating mode, the power absorption has been calculated with the ray tracing code, taking into account of the effect of the plasma/antenna coupling. It is concluded from the consideration of the electron Landau damping that the transition from the ion heating mode to the electron one would be explained by the difference of the electron temperature at the ohmic phase; i.e., T e (0) = 0.7 keV for the case (a) and T e (0) = 1.3 keV for the case (b). (author)

  3. Local heat transfer performance and exit flow characteristics of a miniature axial fan

    International Nuclear Information System (INIS)

    Stafford, Jason; Walsh, Ed; Egan, Vanessa

    2010-01-01

    Dimensional restrictions in electronic equipment have resulted in miniaturization of many existing cooling technologies. In addition to this, cooling solutions are required to dissipate increased thermal loads to maintain component reliability. Axial fans are widely used in electronics cooling to meet such thermal demands. However, if the extent of non-uniform heat transfer rates, produced by highly three-dimensional air patterns is unknown in the design stages, premature component failure may result. The current study highlights these non-uniformities in heat transfer coefficient, using infrared thermography of a miniature axial fan impinging air on a flat plate. Fan rotational speed and distance from the flat plate are varied to encompass heat transfer phenomena resultant from complex exit air flow distribution. Local peaks in heat transfer coefficient have been shown to be directly related to the air flow and fan motor support interaction. Optimum locations for discrete heat source positioning have been identified which are a function of fan to plate spacing and independent of fan rotational speed when the Reynolds number effect is not apparent.

  4. Study of Heat Transfer Characteristics of Nanofluids in an Automotive Radiator

    Science.gov (United States)

    Harsh, R.; Srivastav, Hitish; Balakrishnan, Prabhat; Saini, Vivek; Senthil Kumar, D.; Rajni, K. S.; Thirumalini, S.

    2018-02-01

    This paper presents an experimental study on heat transfer using nanofluid as coolants in engines. Previous studies shows that Al2O3 is found to be more effective in heat transfer due to its high conductive property which is found to increase with concentration. Particles having diameter in the range 10-3 to 10-6 m have low thermal conductivities and cause clogging in the flow section along with significant friction and are highly unstable in solution. Nanoparticles on the other hand are easily dispersed and cause minimal clogging or friction in the flow. In the present work, ethylene glycol-water solution is taken as a base fluid for nanoparticle dispersion. The ratio of water to ethylene glycol used is 80:20 and it has been noted out that heat conduction improved with increasing fraction of ethylene glycol. The experiments were conducted with flow rate of 4,5,6 and 7 L/min and the air flow rate inside the duct was kept constant at 4.9 m/s. The temperature of water in the reservoir is kept at 70°C. The nanoparticles used in this experiment are Cu and TiO2 having particle size less than 80nm. Result shows that there is an improvement of 24.5% in the overall heat transfer coefficient and there was also an increase of 13.9% in the heat transfer rate compared to the base fluid (80:20 Water: EG solution).

  5. Effect on Heat Transfer Characteristics of Nanofluids Flowing under Laminar and Turbulent Flow Regime - A Review

    Science.gov (United States)

    Kumar, Prince; Pandey, K. M., Dr.

    2017-08-01

    Heat transfer is a most important phenomenon that influence the performance of working device. To date several attempts have been made by researchers to minimize the size of heat exchangers in order to reduce the cost. Earlier we use some conventional fluids (water, air, engine oil etc.) for cooling of automobile, refrigeration and some other industrial applications. But it is observed here that by using these fluids there is curb and hindrance in heat transfer rate because of very low thermal conductivity. From last ten-years new generation fluid introduced known as nanofluid. To increase the thermal conductivity of base fluid some amount of nanoparticles is added. Nanofluid have combined properties of nanoparticles as well as base fluid. Researcher found that heat transfer rate fully dependent of the thermal conductivity of nanoparticles as well as nanoparticle size diameter and volume concentration. This review paper summarised the recent research on enhancement of heat transfer and thermal performance of nanofluid as coolant for industrial applications.

  6. Analysis of suspension and heat transfer characteristics of Al2O3 nanofluids prepared through ultrasonic vibration

    International Nuclear Information System (INIS)

    Lin, Cherng-Yuan; Wang, Jung-Chang; Chen, Teng-Chieh

    2011-01-01

    Highlights: → The Al 2 O 3 nanofluid prepared with a surfactant with an HLB value = 12 had the lowest nanoparticle precipitation rate. → The nanofluids prepared with both a dispersant and surfactant had the lowest thermal conductivity . → The thermal conductivity decreased with storage time for all of the Al 2 O 3 nanofluids. → An increase in operating temperature leads to an increase in the thermal conductivity of Al 2 O 3 nanofluids. -- Abstract: Nanofluids that contain nanoparticles with excellent heat transfer characteristics dispersed in a continuous liquid phase are expected to exhibit superior thermal and fluid characteristics to those in a single liquid phase primarily because of their much greater collision frequency and larger contact surface between solid nanoparticles and the liquid phase. One of the major challenges in the use of nanofluids to dissipate the heat generated in electronic equipment such as LEDs is nanoparticles' precipitation due to their poor suspension in the fluid after periods of storage or operation, thereby leading to deterioration in the nanofluids' heat transfer rate. In this study, ultrasonic vibration was employed to prepare Al 2 O 3 nanofluids with a surfactant, a dispersant, and a combination of the two to evaluate their suspension and heat transfer characteristics. The experimental results show the Al 2 O 3 nanofluid prepared with a non-ionic surfactant with a hydrophile lipophile balance (HLB) value of 12 to have the lowest nanoparticle precipitation rate and, accordingly, the highest degree of emulsification stability. Moreover, the nanofluids prepared with both the dispersant and surfactant had the greatest dynamic viscosity and lowest degree of thermal conductivity. Both the precipitation rate and dynamic viscosity of the nanoparticles increased, and their thermal conductivity coefficient decreased, the longer they remained in the Al 2 O 3 nanofluids. Further, an increase in operating temperature caused an

  7. Quality characteristics of pork burger added with albedo-fiber powder obtained from yellow passion fruit (Passiflora edulis var. flavicarpa) co-products.

    Science.gov (United States)

    López-Vargas, Jairo H; Fernández-López, Juana; Pérez-Álvarez, José Ángel; Viuda-Martos, Manuel

    2014-06-01

    The aim of this work determined the technological, nutritional and sensory characteristics of pork burgers, added with different concentrations (2.5 and 5%) of passion fruit albedo (PFA) co-product, obtained from passion fruit juice processing. The addition of PFA on pork burgers improves their nutritional value (higher fiber content). In raw and cooked burger, all textural parameters, except springiness and cohesiveness, were affected by the incorporation of PFA. PFA addition was found to be effective improving the cooking yield, moisture retention and fat retention. The raw and cooked pork burgers added with PFA had lower TBA values and lower counts of aerobic mesophilic bacteria and enterobacteria than the control samples. No Escherichia coli and molds were found in the samples. The overall acceptability scores showed that the most appreciated sample was the one containing 2.5% PFA. According to the results obtained, 2.5 and 5% of PFA addition can be recommended in pork burger production as a new dietary fiber source. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Experimental Studies of the Aerothermal Characteristics of the Project Orion CEV heat Shield in High Speed Transitional and Turbulent Flows

    Science.gov (United States)

    Wadhams, T.P.; MacLean, M.; Holden, M.S.; Cassady, A.M.

    2009-01-01

    An experimental program has been completed by CUBRC exploring laminar, transitional, and turbulent flows over a 7.0% scale model of the Project ORION CEV geometry. This program was executed primarily to answer questions concerning the increase in heat transfer on the windward, or "hot shoulder" of the CEV heat shield from laminar to turbulent flow. To answer these questions CUBRC constructed and instrumented a 14.0 inch diameter Project ORION CEV model and ran a range of Reynolds numbers based on diameter from 1.0 to over 40 million at a Mach number of 8.0. These Reynolds numbers were selected to cover laminar to turbulent heating data on the "hot shoulder". Data obtained during these runs will be used to guide design decisions as they apply to heat shield thickness and extent. Several experiments at higher enthalpies were achieved to obtain data for code validation with real gas effects and transition. CUBRC also performed computation studies of these experiments to aid in the data reduction process and study turbulence modeling.

  9. Study of natural convection heat transfer characteristics. (1) Influence of ventilation duct height

    International Nuclear Information System (INIS)

    Wakamatsu, Mitsuo; Iwaki, Chikako; Ikeda, Tatsumi; Morooka, Shinichi; Ikeda, Hiroshi; Nakada, Kotaro; Masaki, Yoshikazu

    2008-01-01

    Natural cooling system has been investigated in waste storage. It is important to evaluate the flow by natural draft enough to removal the decay heat from the waste. In this study, we carried out the fundamental experiment of ventilation duct height effect for natural convection on vertical cylindrical heater in atmospheric air. The scale of test facility is about 4m height with single heater. The heating value is varied in the range of 33-110W, where Rayleigh number is over 10 10 . Natural convection flow rate were calculated by measured velocity with thermo anemometer in the inlet duct. The temperature of the cylindrical heater wall and fluid were measured with thermocouples. It was found that the heat transfer coefficient difference between long duct and short duct is small in this experiment. (author)

  10. Characteristic performance of radio-frequency(RF) plasma heating using inverter RF power supplies

    International Nuclear Information System (INIS)

    Imai, Takahiro; Uesugi, Yoshihiko; Takamura, Shuichi; Sawada, Hiroyuki; Hattori, Norifumi

    2000-01-01

    High heat flux plasma are produced by high powe (∼14 kW) ICRF heating using inverter power supplies in the linear divertor simulator NAGDIS-II. The power flow of radiated rf power is investigated by a calorimetric method. Conventional power calculation using antenna voltage and current gives that about 70% of the rf power is radiated into the plasma. But increase of the heat load at the target and anode is about 10% of the rf power. Through this experiment, we find that about half of the rf power is lost at the antenna surface through the formation of rf induced sheath. And about 30% of the power is lost into the vacuum vessel through the charge exchange and elastic collision of ions with neutrals. (author)

  11. Experimental study on heat transfer characteristic of T-junction in cooling system of PWR

    International Nuclear Information System (INIS)

    Wang Haijun; Lu Donghua; Luo Yushan; Chen Tingkuan

    2002-01-01

    The local near wall fluid temperature and heat transfer coefficient distribution in three different areas were measured for T-junction with and without thermal sleeve where jet injected vertically down to the main flow. Flow with velocity ratio between 0.01 and 1.5 were measured. The diameter ratio of jet pipe to main pipe is 0.16. It was found at that downstream of the jet, the thermal sleeve has little effect on heat transfer. At the inlet of the jet and inside the jet tube, the thermal sleeve distinctly affect heat transfer coefficient and near wall fluid temperature. The thermal sleeve's effect is more marked when the velocity ratio becomes larger

  12. Hydrodynamics and heat transfer characteristics of liquid pools with bubble agitation

    International Nuclear Information System (INIS)

    Blottner, F.G.

    1979-11-01

    Estimates are given for the heat transfer coefficients at various interfaces which occur in molten pools on concrete. Previous simulant experiments and correlations are used to determine the hydrodynamic behavior of the pool and heat transfer coefficients for the liquids of interest. Other studies assume a gas film occurs between the concrete and molten pool, but the results of this investigation do not confirm this assumption. The results also indicate the significant influence the very viscous concrete slag has on the properties of the molten pool. Additional experiments and analysis are needed to improve the accuracy of the heat transfer coefficients estimated and to understand the behavior of the concrete slag at the interface between the pool and decomposing concrete

  13. Effects of Second-Order Slip and Viscous Dissipation on the Analysis of the Boundary Layer Flow and Heat Transfer Characteristics of a Casson Fluid

    Directory of Open Access Journals (Sweden)

    Mohammad M. Rahman

    2016-11-01

    Full Text Available The aim of the present study is to analyze numerically the steady boundary layer flow and heat transfer characteristics of Casson fluid with variable temperature and viscous dissipation past a permeable shrinking sheet with second order slip velocity. Using appropriate similarity transformations, the basic nonlinear partial differential equations have been transformed into ordinary differential equations. These equations have been solved numerically for different values of the governing parameters namely: shrinking parametersuction parameterCasson parameterfirst order slip parametersecond order slip parameter  Prandtl number  and the Eckert number  using the bvp4c function from MATLAB. A stability analysis has also been performed. Numerical results have been obtained for the reduced skin-friction, heat transfer and the velocity and temperature profiles. The results indicate that dual solutions exist for the shrinking surface for certain values of the parameter space. The stability analysis indicates that the lower solution branch is unstable, while the upper solution branch is stable and physically realizable. In addition, it is shown that for a viscous fluida very good agreement exists between the present numerical results and those reported in the open literature. The present results are original and new for the boundary-layer flow and heat transfer past a shrinking sheet in a Casson fluid. Therefore, this study has importance for researchers working in the area of non-Newtonian fluids, in order for them to become familiar with the flow behavior and properties of such fluids.

  14. Natural convection heat transfer characteristics of the molten metal pool with solidification by boiling coolant

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jae Seon; Suh, Kune Yull; Chung, Chang Hyun [Seoul National University, Seoul (Korea, Republic of); Paark, Rae Joon; Kim, Sang Baik [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    This paper presents results of experimental studies on the heat transfer and solidification of the molten metal pool with overlying coolant with boiling. The metal pool is heated from the bottom surface and coolant is injected onto the molten metal pool. Ad a result, the crust, which is a solidified layer, may form at the top of the molten metal pool. Heat transfer is accomplished by a conjugate mechanism, which consists of the natural convection of the molten metal pool, the conduction in the crust layer and the convective boiling heat transfer in the coolant. This work examines the crust formation and the heat transfer rate on the molten metal pool with boiling coolant. The simulant molten pool material is tin (Sn) with the melting temperature of 232 deg C. Demineralized water is used as the working coolant. The crust layer thickness was ostensibly varied by the heated bottom surface temperature of the test section, but not much affected by the coolant injection rate. The correlation between the Nusselt number and the Rayleigh number in the molten metal pool region of this study is compared against the crust formation experiment without coolant boiling and the literature correlations. The present experimental results are higher than those from the experiment without coolant boiling, but show general agreement with the Eckert correlation, with some deviations in the high and low ends of the Rayleigh number. This discrepancy is currently attributed to concurrent rapid boiling of the coolant on top of the metal layer. 10 refs., 4 figs., 1 tab. (Author)

  15. Natural convection heat transfer characteristics of the molten metal pool with solidification by boiling coolant

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jae Seon; Suh, Kune Yull; Chung, Chang Hyun [Seoul National University, Seoul (Korea, Republic of); Paark, Rae Joon; Kim, Sang Baik [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    This paper presents results of experimental studies on the heat transfer and solidification of the molten metal pool with overlying coolant with boiling. The metal pool is heated from the bottom surface and coolant is injected onto the molten metal pool. Ad a result, the crust, which is a solidified layer, may form at the top of the molten metal pool. Heat transfer is accomplished by a conjugate mechanism, which consists of the natural convection of the molten metal pool, the conduction in the crust layer and the convective boiling heat transfer in the coolant. This work examines the crust formation and the heat transfer rate on the molten metal pool with boiling coolant. The simulant molten pool material is tin (Sn) with the melting temperature of 232 deg C. Demineralized water is used as the working coolant. The crust layer thickness was ostensibly varied by the heated bottom surface temperature of the test section, but not much affected by the coolant injection rate. The correlation between the Nusselt number and the Rayleigh number in the molten metal pool region of this study is compared against the crust formation experiment without coolant boiling and the literature correlations. The present experimental results are higher than those from the experiment without coolant boiling, but show general agreement with the Eckert correlation, with some deviations in the high and low ends of the Rayleigh number. This discrepancy is currently attributed to concurrent rapid boiling of the coolant on top of the metal layer. 10 refs., 4 figs., 1 tab. (Author)

  16. Investigations of the gas-side heat transfer and flow characteristics of steam generators in AGR stations

    Energy Technology Data Exchange (ETDEWEB)

    Lis, J [Central Electricity Research Laboratories, Leatherhead, Surrey (United Kingdom)

    1984-07-01

    This paper describes the experimental and analytical investigations of the gas-side heat transfer and flow characteristics of steam generators in the AGR stations carried out by CERL. The majority of the experimental work on heat transfer and flow characteristics of close-packed tube arrangements in cross-flow of gases is carried out in a pressurised heat exchanger rig. The rig is operated on-line by a dedicated PDP 11/40 computer over the range of Reynolds number 10{sup 4} to 3x10{sup 5}. Atmospheric wind tunnels employing either small or large scale models of the specific sections of steam generators are used for a variety of supplementary and development studies. Various measurements techniques and, in particular, LDA and hot wire anemometry employed in these studies are described. The more important aspects of various investigations are illustrated by typical results. In order to ensure the efficient operation and integrity of steam generators under asymmetric boundary conditions a MIX suite of 2-dimensional codes has been developed. The codes calculate the gas and water/steam flow and temperature distributions in each channel of the steam generator taking into account thermal mixing in the gas as it passes through the generator. Application of the MIX codes to the solution of various operational problems is illustrated by typical examples and the continuing exercise of validating the codes against plant operational data is discussed. (author)

  17. Summary of experimental core turbulence characteristics in ohmic and electron cyclotron resonance heated discharges in T-10 tokamak plasmas

    International Nuclear Information System (INIS)

    Vershkov, V.A.; Shelukhin, D.A.; Soldatov, S.V.; Urazbaev, A.O.; Grashin, S.A.; Eliseev, L.G.; Melnikov, A.V.

    2005-01-01

    This report summarizes the results of experimental turbulence investigations carried out at T-10 for more than 10 years. The turbulence characteristics were investigated using correlation reflectometry, multipin Langmuir probe (MLP) and heavy ion beam probe diagnostics. The reflectometry capabilities were analysed using 2D full-wave simulations and verified by direct comparison using a MLP. The ohmic and electron cyclotron resonance heated discharges show the distinct transition from the core turbulence, having complex spectral structure, to the unstructured one in the scrape-off layer. The core turbulence includes 'broad band, quasi-coherent' features, arising due to the excitation of rational surfaces with high poloidal m-numbers, with a low frequency near zero and specific oscillations at 15-30 kHz. All experimentally measured properties of low frequency and high frequency quasi-coherent oscillations are in good agreement with predictions of linear theory for the ion temperature gradient/dissipative trapped electron mode instabilities. Significant local changes in the turbulence characteristics were observed at the edge velocity shear layer and in the core near q = 1 radius after switching off the electron cyclotron resonance heating (ECRH). The local decrease in the electron heat conductivity and decrease in the turbulence level could be evidence of the formation of an electron internal transport barrier. The dynamic behaviour of the core turbulence was also investigated for the case of fast edge cooling and the beginning phase of ECRH

  18. Investigations of the gas-side heat transfer and flow characteristics of steam generators in AGR stations

    International Nuclear Information System (INIS)

    Lis, J.

    1984-01-01

    This paper describes the experimental and analytical investigations of the gas-side heat transfer and flow characteristics of steam generators in the AGR stations carried out by CERL. The majority of the experimental work on heat transfer and flow characteristics of close-packed tube arrangements in cross-flow of gases is carried out in a pressurised heat exchanger rig. The rig is operated on-line by a dedicated PDP 11/40 computer over the range of Reynolds number 10 4 to 3x10 5 . Atmospheric wind tunnels employing either small or large scale models of the specific sections of steam generators are used for a variety of supplementary and development studies. Various measurements techniques and, in particular, LDA and hot wire anemometry employed in these studies are described. The more important aspects of various investigations are illustrated by typical results. In order to ensure the efficient operation and integrity of steam generators under asymmetric boundary conditions a MIX suite of 2-dimensional codes has been developed. The codes calculate the gas and water/steam flow and temperature distributions in each channel of the steam generator taking into account thermal mixing in the gas as it passes through the generator. Application of the MIX codes to the solution of various operational problems is illustrated by typical examples and the continuing exercise of validating the codes against plant operational data is discussed. (author)

  19. Characteristics of autoignited laminar lifted flames in heated coflow jets of carbon monoxide/hydrogen mixtures

    KAUST Repository

    Choi, Byungchul; Chung, Suk-Ho

    2012-01-01

    and then increased as the jet velocity increased. Based on the mechanism in which the autoignited laminar lifted flame is stabilized by ignition delay time, the liftoff height can be influenced not only by the heat loss, but also by the preferential diffusion between

  20. Effect of T6 heat treatment on damping characteristics of Al/RHA ...

    Indian Academy of Sciences (India)

    Abstract. In the present work, effect of T6 heat treatment on the damping behaviour of aluminum/rice husk ash .... alloy-based composites, there is dearth of information on the damping ... fication. Using the process 4, 6 and 8% by weight, RHA.

  1. Numerical investigation of heat transfer characteristics in utility boilers of oxy-coal combustion

    International Nuclear Information System (INIS)

    Hu, Yukun; Li, Hailong; Yan, Jinyue

    2014-01-01

    Highlights: • Air-coal and oxy-coal combustion in an industrial scale PF boiler were simulated in ANSYS FLUENT. • The O 2 concentration of 33 vol% in the oxy-coal combustion case matches the air-coal combustion case most closely. • The moisture in the flue gas has little impact on flame temperature, but positive impact on surface incident radiation. - Abstract: Oxy-coal combustion has different flue gas composition from the conventional air-coal combustion. The different composition further results in different properties, such as the absorption coefficient, emissivity, and density, which can directly affect the heat transfer in both radiation and convection zones of utility boilers. This paper numerically studied a utility boiler of oxy-coal combustion and compares with air-coal combustion in terms of flame profile and heat transferred through boiler side walls in order to understand the effects of different operating conditions on oxy-coal boiler retrofitting and design. Based on the results, it was found that around 33 vol% of effective O 2 concentration ([O 2 ] effective ) the highest flame temperature and total heat transferred through boiler side walls in the oxy-coal combustion case match to those in the air-coal combustion case most; therefore, the 33 vol% of [O 2 ] effective could result in the minimal change for the oxy-coal combustion retrofitting of the existing boiler. In addition, the increase of the moisture content in the flue gas has little impact on the flame temperature, but results in a higher surface incident radiation on boiler side walls. The area of heat exchangers in the boiler was also investigated regarding retrofitting. If boiler operates under a higher [O 2 ] effective , to rebalance the load of each heat exchanger in the boiler, the feed water temperature after economizer can be reduced or part of superheating surfaces can be moved into the radiation zone to replace part of the evaporators

  2. Characteristics of water obtained by dewatering cyanobacteria-containing sludge formed during drinking water treatment, including C-, N-disinfection byproduct formation.

    Science.gov (United States)

    Xu, Hangzhou; Pei, Haiyan; Jin, Yan; Xiao, Hongdi; Ma, Chunxia; Sun, Jiongming; Li, Hongmin

    2017-03-15

    This is the first study to systematically investigate the characteristics of the water obtained by dewatering cyanobacteria-containing sludge generated in the drinking water treatment plant, including formation of C- and N-disinfection by-products (DBPs). Results showed that this 'dewatering water' (DW) had different properties when the sludge was stored at different times. The content of dissolved organic matter (DOM) and microcystins (MCs) in the DW were low when the sludge was treated or disposed of within 4 days; correspondingly, the C-, N-DBP production was also low. However, due to the damage of algal cells to some extent, the DOM and MC levels increased significantly for storage time longer than 4 days; the production of C-, N-DBPs also increased. There were also obvious differences in the characteristics of the DW from sludges generated with different coagulant species. Due to the better protective effect of FeCl 3 and polymeric aluminium ferric chloride (PAFC) flocs, the DOM and MC levels and the production of C-, N-DBPs in the DW with FeCl 3 and PAFC coagulation were lower than those with AlCl 3 coagulation, even though the sludges were stored for the same amount of time. Furthermore, because of the formation of Al and Fe hydroxides, precipitated onto the surface of flocs, the soluble Al and Fe in the DW decreased with increased storage time, especially in the first four days. Overall, this study revealed the trends in variation of DW quality for cyanobacteria-containing sludges formed with different coagulants, then FeCl 3 and PAFC coagulants are recommended and sludge should be treated or disposed of within 4 days. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Heat Transfer Characteristics of a Focused Surface Acoustic Wave (F-SAW Device for Interfacial Droplet Jetting

    Directory of Open Access Journals (Sweden)

    Donghwi Lee

    2018-06-01

    Full Text Available In this study, we investigate the interfacial droplet jetting characteristics and thermal stability of a focused surface acoustic wave device (F-SAW. An F-SAW device capable of generating a 20 MHz surface acoustic wave by applying sufficient radio frequency power (2–19 W on a 128°-rotated YX-cut piezoelectric lithium niobate substrate for interfacial droplet jetting is proposed. The interfacial droplet jetting characteristics were visualized by a shadowgraph method using a high-speed camera, and a heat transfer experiment was conducted using K-type thermocouples. The interfacial droplet jetting characteristics (jet angle and height were analyzed for two different cases by applying a single interdigital transducer and two opposite interdigital transducers. Surface temperature variations were analyzed with radio frequency input power increases to evaluate the thermal stability of the F-SAW device in air and water environments. We demonstrate that the maximum temperature increase of the F-SAW device in the water was 1/20 of that in the air, owing to the very high convective heat transfer coefficient of the water, resulting in prevention of the performance degradation of the focused acoustic wave device.

  4. Characteristic evaluations of BWR uprate method based on heat balance shift concept

    International Nuclear Information System (INIS)

    Kitou, Kazuaki; Aoyama, Motoo; Shiina, Kouji; Sasaki, Hiroshi; Yoshikawa, Kazuhiro

    2007-01-01

    Reactor power uprate of nuclear power plants is an efficient plant operating method. Most BWR plants need the exchange of high pressure turbines when plant thermal power increases over 5% because main steam flow rate exceeds the limitation of inlet steam flow rate of a high pressure turbine. Therefore, the new power uprate method named heat balance shift power uprate method has been developed. This method decreases feedwater temperature with increasing plant thermal power not to increase main steam flower rate. This study clarified that the heat balance shift method could increase plant electric power up to 2.8% compared with conventional power uprate method without the exchange of a high pressure turbine. (author)

  5. Physiological characteristics under the influence of heat stress working in the hot environment, (4)

    International Nuclear Information System (INIS)

    Nagasaka, Akihiko; Yoshino, Kenji; Takano, Ken-ichi

    1987-01-01

    There is a possibility that physical and mental stress appears under hot environmental condition for the cause of wearing protection suits on reactor maintenance work. It is important to reduce heat stress rapidly and effectively. This paper mentioned following about the results of static state and simulation work done by testees with or without protection suits under 25 kinds of temperatures and wind velocities in a artificial climate chamber. (1) the correlation between ambient temperatures or wind velocities and subjective symptoms without protection suits. (2) the correlation between ambient temperatures or wind velocities and skin temperatures without protection suits. (3) investigation of the parts of body affecting subjective symptoms. (4) the correlation between ambient temperatures or wind velocities and skin temperatures at working with protection suits. (5) working out countermeasures of recovery from heat stress with the index of skin temperatures and subjective symptoms. (author)

  6. Flow and heat transfer characteristics in a channel having furrowed wall based on sinusoidal wave

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiansheng; Gao, Xiaoming; Li, Weiyi [Tianjin University, Tianjin (Switzerland)

    2015-11-15

    The effect of wall geometry on the flow and heat transfer in a channel with one lower furrowed and an upper flat wall kept at a uniform temperature is investigated by large eddy simulation. Three channels, one with sinusoidal wavy surface having the ratio (amplitude to wavelength) α/λ=0.05 and the other two with furrowed surface derived from the sinusoidal curve, are considered. The numerical results show that the streamwise vortices center is located near the lower wall and vary along the streamwise on various furrow surfaces. The furrow geometry increases the pressure drag and decreases the friction drag of the furrowed surface compared with that of the smooth surface; consequently, the total drag is increased for the augment of pressure drag. As expected, the heat transfer performance has been improved. Finally, a thermal performance factor is defined to evaluate the performance of the furrowed wall.

  7. Numerical investigation of influence on heat transfer characteristics to pneumatically conveyed dense phase flow by selecting models and boundary conditions

    Science.gov (United States)

    Zheng, Y.; Liu, Q.; Li, Y.

    2012-03-01

    Solids moving with a gas stream in a pipeline can be found in many industrial processes, such as power generation, chemical, pharmaceutical, food and commodity transfer processes. A mass flow rate of the solids is important characteristic that is often required to be measured (and controlled) to achieve efficient utilization of energy and raw materials in pneumatic conveying systems. The methods of measuring the mass flow rate of solids in a pneumatic pipeline can be divided into direct and indirect (inferential) measurements. A thermal solids' mass flow-meter, in principle, should ideally provide a direct measurement of solids flow rate, regardless of inhomogeneities in solids' distribution and environmental impacts. One key issue in developing a thermal solids' mass flow-meter is to characterize the heat transfer between the hot pipe wall and the gas-solids dense phase flow. The Eulerian continuum modeling with gas-solid two phases is the most common method for pneumatic transport. To model a gas-solid dense phase flow passing through a heated region, the gas phase is described as a continuous phase and the particles as the second phase. This study aims to describe the heat transfer characteristics between the hot wall and the gas-solids dense phase flow in pneumatic pipelines by modeling a turbulence gas-solid plug passing through the heated region which involves several actual and crucial issues: selections of interphase exchange coefficient, near-wall region functions and different wall surface temperatures. A sensitivity analysis was discussed to identify the influence on the heat transfer characteristics by selecting different interphase exchange coefficient models and different boundary conditions. Simulation results suggest that sensitivity analysis in the choice of models is very significant. The simulation results appear to show that a combination of choosing the Syamlal-O'Brien interphase exchange coefficient model and the standard k-ɛ model along with

  8. Heat transfer characteristics of horizontally oriented multi-layered annular insulation, (1)

    International Nuclear Information System (INIS)

    Hino, Ryutaro; Simomura, Hiroaki

    1985-04-01

    A computer code has been developed to analyze the natural convection heat transfer in a horizontal annular insulation layer of a hot gas duct when local gaps and inhomogeneity of filling density of insulation materials exist. This computer code simulates local gaps and inhomogeneity of filling density by a multi-layer model. This report describes an analytical model, a numerical method, an outline of program and some calculation results. (author)

  9. Time-temperature characteristics of the various heat-affected zones in HT-9 weldments

    International Nuclear Information System (INIS)

    Foulds, J.R.

    1984-01-01

    Temperatures at different distances from the fusion boundary were measured during GTA weld depositing MTS-4 filler wire on 9.52-mm (3/8 in.) thick HT-9 plate. Peak temperature measurements indicate each of the heat-affected regions to be austenitized. An exponential expression has been used to describe the cooling curves as a function of peak temperature (or distance) from the fusion boundary

  10. Pool boiling characteristics and critical heat flux mechanisms of microporous surfaces and enhancement through structural modification

    Science.gov (United States)

    Ha, Minseok; Graham, Samuel

    2017-08-01

    Experimental studies have shown that microporous surfaces induce one of the highest enhancements in critical heat flux (CHF) during pool boiling. However, microporous surfaces may also induce a very large surface superheat (>100 °C) which is not desirable for applications such as microelectronics cooling. While the understanding of the CHF mechanism is the key to enhancing boiling heat transfer, a comprehensive understanding is not yet available. So far, three different theories for the CHF of microporous surfaces have been suggested: viscous-capillary model, hydrodynamic instability model, and dryout of the porous coatings. In general, all three theories account for some aspects of boiling phenomena. In this study, the theories are examined through their correlations with experimental data on microporous surfaces during pool boiling using deionized (DI) water. It was found that the modulation of the vapor-jet through the pore network enables a higher CHF than that of a flat surface based on the hydrodynamic instability theory. In addition, it was found that as the heat flux increases, a vapor layer grows in the porous coatings described by a simple thermal resistance model which is responsible for the large surface superheat. Once the vapor layer grows to fill the microporous structure, transition to film boiling occurs and CHF is reached. By disrupting the formation of this vapor layer through the fabrication of channels to allow vapor escape, an enhancement in the CHF and heat transfer coefficient was observed, allowing CHF greater than 3500 kW/m2 at a superheat less than 50 °C.

  11. Confinement characteristics of high-energy ions produced by ICRF heating in the large helical device

    International Nuclear Information System (INIS)

    Kumazawa, R; Saito, K; Torii, Y; Mutoh, T; Seki, T; Watari, T; Osakabe, M; Murakami, S; Sasao, M; Watanabe, T; Yamamoto, T; Notake, T; Takeuchi, N; Saida, T; Shimpo, F; Nomura, G; Yokota, M; Kato, A; Zao, Y; Okada, H; Isobe, M; Ozaki, T; Narihara, K; Nagayama, Y; Inagaki, S; Morita, S; Krasilnikov, A V; Idei, H; Kubo, S; Ohkubo, K; Sato, M; Shimozuma, T; Yoshimura, Y; Ikeda, K; Nagaoka, K; Oka, Y; Takeiri, Y; Tsumori, K; Ashikawa, N; Emoto, M; Funaba, H; Goto, M; Ida, K; Kobuchi, T; Liang, Y; Masuzaki, S; Minami, T; Miyazawa, J; Morisaki, T; Muto, S; Nakamura, Y; Nakanishi, H; Nishimura, K; Noda, N; Ohdachi, S; Peterson, B J; Sagara, A; Sakakibara, S; Sakamoto, R; Sato, K; Shoji, M; Suzuki, H; Tanaka, K; Toi, K; Tokuzawa, T; Watanabe, K Y; Yamada, I; Yamamoto, S; Yoshinuma, M; Yokoyama, M; Watanabe, K-Y; Kaneko, O; Kawahata, K; Komori, A; Ohyabu, N; Yamada, H; Yamazaki, K; Sudo, S; Matsuoka, K; Hamada, Y; Motojima, O; Fujiwara, M

    2003-01-01

    The behaviour of high-energy ions accelerated by an ion cyclotron range of frequency (ICRF) electric field in the large helical device (LHD) is discussed. A better confinement performance of high-energy ions in the inward-shifted magnetic axis configuration was experimentally verified by measuring their energy spectrum and comparing it with the effective temperature determined by an electron slowing down process. In the standard magnetic axis configuration a saturation of the measured tail temperature was observed as the effective temperature was increased. The ratio between these two quantities is a measure of the quality of transfer efficiency from high-energy ions to a bulk plasma; when this efficiency was compared with Monte Carlo simulations the results agreed fairly well. The ratio of the stored energy of the high-energy ions to that of the bulk plasma was measured using an ICRF heating power modulation method; it was deduced from phase differences between total and bulk plasma stored energies and the modulated ICRF heating power. The measured high energy fraction agreed with that calculated using the injected ICRF heating power, the transfer efficiency determined in the experiment and the confinement scaling of the LHD plasma

  12. Some characteristics of heat production by stationary parabolic, cylindrical solar concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Bojic, M.; Marjanovic, N.; Miletic, I.; Mitic, A. [Kragujevac Univ., Kragujevac (Serbia). Faculty of Mechanical Engineering; Stefanovic, V. [Nis Univ., Nis (Serbia). Faculty of Mechanical Engineering

    2009-07-01

    The use of solar energy for heating, cooling and electricity production was discussed with particular reference to the use of a stationary, asymmetric solar concentrator for conversion of solar energy to heat using a reflector and absorber. The infinite length CP-0A type stationary parabolic, cylindrical solar concentrator for heat production consists of the absorber (with water pipes) and parabolic, cylindrical reflector (with a metal surface). It has a geometrical concentration ratio of up to 4. This paper reported on a study that used the CATIA computer software to investigate how direct solar radiation approaches the concentrator aperture and the concentrator reflector. The propagation of light rays inside the concentrator to reach the absorber surface was examined. The study showed that the solar ray either hits the absorber directly or it bounces one or several time from the concentrator reflector. The efficiency of light rays was also calculated as a function of angles of incident of solar rays and type of reflector surface. 5 refs., 8 figs.

  13. Magnetic Characteristics of Active Region Heating Observed with TRACE, SOHO/EIT, and Yohkoh/SXT

    Science.gov (United States)

    Porter, J. G.; Falconer, D. A.; Moore, R. L.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Over the past several years, we have reported results from studies that have compared the magnetic structure and heating of the transition region and corona (both in active regions and in the quiet Sun) by combining X-ray and EUV images from Yohkoh and Solar and Heliospheric Observatory (SOHO) with photospheric magnetograms from ground-based observatories. Our findings have led us to the hypothesis that most heating throughout the corona is driven from near and below the base of the corona by eruptive microflares occurring in compact low-lying "core magnetic fields (i.e., fields rooted along and closely enveloping polarity inversion lines in the photospheric magnetic flux). We now extend these studies, comparing sequences of UV images from Transition Region and Coronal Explorer (TRACE) with longitudinal magnetograms from Kitt Peak and vector magnetograms from MUSIC. These comparisons confirm the previous results regarding the importance of core-field activity to active region heating. Activity in fields associated with satellite polarity inclusions and/or magnetically sheared configurations is especially prominent. This work is funded by NASA's Office of Space Science through the Sun-Earth Connection Guest Investigator Program and the Solar Physics Supporting Research and Technology Program.

  14. Characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific

    Institute of Scientific and Technical Information of China (English)

    LI Gen; REN BaoHua; ZHENG JianOiu; WANG Jun

    2009-01-01

    Based on the daily turbulent heat fluxes and related meteorological variables dataeets (1985-2006) from Objectively Analyzed air-sea Fluxes (OAFlux) Project of Woods Hole Oceanographic Institution (WHOI), characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific are analyzed by linear perturbation method and correlation analysis. It can be concluded that: 1) the distribution of low-frequency oscillation intensity of latent heat flux (LHF) over the northwest Pacific is mainly affected by that of low-frequency oscillation intensity of anomalous air-eea humidity gradient (△q') as well as mean air-eea humidity gradient (△q), while the distribution of low-frequency oscillation Intensity of sensible heat flux (SHF) is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea temperature gradient (△T'). 2) The low-frequency oscillation of turbulent heat fluxes over the northwest Pacific is the strongest in winter and the weakest in summer. And the seasonal transition of low-frequency oscillation intensity of LHF is jointly influenced by those of low-frequency oscillation intensity of △q', low-frequency oscillation intensity of anomalous wind speed (U'), △q and mean wind speed (U), while the seasonal transition of low-frequency oscillation intensity of SHF is mainly influenced by those of low-frequency oscillation Intensity of △T' and U. 3) Over the tropical west Pacific and sea areas north of 20ON, the low-frequency oscillation of LHF (SHF) is mainly influenced by atmospheric variables qa' (Ta') and U', indicating an oceanic response to overlying atmospheric forcing. In contrast, over the tropical eastern and central Pacific south of 20°N, qs' (Ts') also greatly influences the low-frequency oscillation of LHF (SHF).

  15. Spatial and temporal characteristics of heat waves over Central Europe in an ensemble of regional climate model simulations

    Czech Academy of Sciences Publication Activity Database

    Lhotka, Ondřej; Kyselý, Jan

    2015-01-01

    Roč. 45, č. 9 (2015), s. 2351-2366 ISSN 0930-7575 R&D Projects: GA ČR GAP209/10/2265 EU Projects: European Commission(XE) 505539 - ENSEMBLES Program:FP6 Institutional support: RVO:68378289 Keywords : heat waves * regional climate models * land–atmosphere coupling * spatial characteristics * interannual variability * ENSEMBLES project Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 4.708, year: 2015 http://link.springer.com/article/10.1007%2Fs00382-015-2475-7

  16. A multiple p-n junction structure obtained from as-grown Czochralski silicon crystals by heat treatment - Application to solar cells

    Science.gov (United States)

    Chi, J. Y.; Gatos, H. C.; Mao, B. Y.

    1980-01-01

    Multiple p-n junctions have been prepared in as-grown Czochralski p-type silicon through overcompensation near the oxygen periodic concentration maxima by oxygen thermal donors generated during heat treatment at 450 C. Application of the multiple p-n-junction configuration to photovoltaic energy conversion has been investigated. A new solar-cell structure based on multiple p-n-junctions was developed. Theoretical analysis showed that a significant increase in collection efficiency over the conventional solar cells can be achieved.

  17. The impact of the accuracy of indicator diagrams on the heat release characteristics calculation, used in the diagnosis of marine diesel engine

    Directory of Open Access Journals (Sweden)

    Witkowski Kazimierz

    2017-01-01

    Full Text Available The paper analyzes the possibility to use the electronic type indicators in the diagnosis of marine engines. It has been shown that in-depth analysis of indicator diagrams would be useful – calculation of heat release characteristics. To make this possible, measuring indicated systems should meet a number of important requirements in or-der to ensure that they can be used for the diagnostic purposes. These includes: high precision sensors for the measurement of cylinder pressure, high speed and accuracy of measuring and recording of measured values. These also includes reliable determination of the top dead center piston (TDC. In order to demonstrate the impact of positional error TDC, simulation study was conducted in which indicated diagrams were used, obtained on a medium-speed four-stroke marine diesel engine type A25/30 and the low-speed two-stroke marine diesel engine type RTA76, Sulzer company.

  18. Magnetic and structural properties of Fe{sub 65}Co{sub 35} alloys obtained by melting, high-energy milling and heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Trifu, A.V.; Dorolti, E. [Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca (Romania); Takacs, A.F., E-mail: albert.takacs@phys.ubbcluj.ro [Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca (Romania); Chicinaş, I. [Materials Sciences and Engineering Department, Technical University of Cluj-Napoca, 103-105 Muncii Avenue, 400641 Cluj-Napoca (Romania); Isnard, O. [Institut Néel, CNRS, Université Joseph Fourier, BP 166X, 38042 Grenoble Cédex 9 (France); Pop, V. [Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca (Romania)

    2013-11-20

    The influence of milling and annealing conditions on the structural and magnetic behaviour of mechanically milled Fe{sub 65}Co{sub 35} alloys has been studied. By differential scanning calorimetry measurements we determined the internal stress relaxation temperature, recrystallisation temperature and structural order/disorder transition temperature of bulk and mechanical milled Fe{sub 65}Co{sub 35}. The width of the X-ray diffraction peaks was found to increase with the milling time. Two types of annealing were performed: a conventional heat treatment at 500, 550 and 600 °C for 2 h and a rapid annealing for a maximum of 2 min at 700, 750 or 800 °C followed by quenching. Crystallite size increases with increasing heat treatment temperature and time, as both are parameters that influence the magnetic properties of the sample. Magnetic permeability variations result from internal stress evolution, changes in crystallite size, supposing that the crystallite size of the annealed samples is at the border between viability of the Herzer model and the classical behaviour of the permeability vs. crystallite size.

  19. Heat transfer characteristics of UF6 in a container heated from outer surface. Pt. 1. Thermal hydraulic analysis method taking account of phase change and volume expansion

    International Nuclear Information System (INIS)

    Wataru, Masumi; Gomi, Yoshio; Yamakawa, Hidetsugu; Tsumune, Daisuke

    1995-01-01

    Natural UF6 is transported in a steel container from foreign countries to the enrichment plant in Japan. If the container meets fire accident, it is heated by fire (800degC) and rupture of the container may occur. For the safety point of view, it is necessary to know whether rupture occurs or not. Because UF6 has a radiological and chemical hazards, it is difficult to perform a demonstration test with UF6. So thermal calculation method has to be developed. The rupture is caused by UF6 gaseous pressure or volume expansion of liquid UF6. To know time history of internal pressure and temperature distribution in the container, it is important to evaluate thermal phenomena of UF6. When UF6 is heated, it changes from solid to liquid or gas at low temperature (64degC) and then its volume expands little by little. In this study, thermal calculation method has been developed taking phase change and thermal expansion of UF6 into account. In the calculation, a two-dimensional model is adopted and natural convection of liquid UF6 is analyzed. As a result of this study, numerical solutions have been obtained taking phase change and volume expansion into account. (author)

  20. Two-dimensional nonlinear heat conduction wave in a layer-inhomogeneous medium and the characteristics of heat transfer in laser thermonuclear fusion targets

    International Nuclear Information System (INIS)

    Gus'kov, Sergei Yu; Doskach, I Ya

    1999-01-01

    An analytical solution is obtained to the problem of propagation of a 2-D nonlinear heat conduction wave from a cylindrical energy source, which acts in a planar layer of a material surrounded by a medium with different mass density and degree of ionisation. A theoretical justification is given of several interesting phenomena of 2-D thermal wave propagation through an inhomogeneous medium. These phenomena are related to the difference between the thermal wave velocities in the media with different thermal diffusivities. When the mass density in a layer experiencing the action of an energy source exceeds the density of the surrounding medium, the thermal wave front is shown to glide along the layer boundaries with a spatial velocity exceeding the velocity of the wave inside the layer. Moreover, there is a possibility of 'themal flow' of a layer across the boundaries between the layer and the surrounding medium in front of a thermal wave propagating inside the layer. The problems of heat transfer in multilayer targets for laser thermonuclear fusion are considered as an application. (interaction of laser radiation with matter. laser plasma)

  1. An investigation of flow and resistance characteristics of heat exchanger with the 2-D LDV system and visualization technique

    International Nuclear Information System (INIS)

    Wang Zongsen; Shen Xiong; Xu Yuanhui; Bi Shuxun

    1987-12-01

    An experimental study of the heat exchanger which would be used in a nuclear reactor for low temperature heat-supplying is presented. A 2-D Laser Doppler Velocimeter was used as a unique technique to measure the mean velocity and turbulence intensity distributions in different sections of the model. The relationship between the resistance coefficient and Reynolds number also obtained in terms of the total pressure rakes covered by the casings and the wall static pressure pick-up holes. The flow visualization has realized by using a piece of light source with an Argon-Ion laser. It is apparent that the polystyrene particles seeded in the flow can trace the mean flow. The results showed that the self-similar phenomenon exists in the tube bundle flow system. There are some secondary vortices in the cross sections between two passages of the model

  2. On the calculation of flow and heat transfer characteristics for CANDU-type 19-rod fuel bundles

    International Nuclear Information System (INIS)

    Yuh-Shan Yueh; Ching-Chang Chieng

    1987-01-01

    A numerical study is reported of flow and heat transfer in a CANDU-type 19 rod fuel bundle. The flow domain of interest includes combinations of trangular, square, and peripheral subchannels. The basic equations of momentum and energy are solved with the standard k--ε model of turbulence. Isotropic turbulent viscosity is assumed and no secondary flow is considered for this steady-state, fully developed flow. Detailed velocity and temperature distributions with wall shear stress and Nusselt number distributions are obtained for turbulent flow of Re = 4.35 x 10 4 , 10 5 , 2 x 10 5 , and for laminar flow of Re--2400. Friction factor and heat transfer ceofficients of various subchannels inside the full bundle are compared with those of infinite rod arrays of triangular or square arrangements. The calculated velocity contours of peripheral subchannel agreed reasonably with measured data

  3. Timing Effects of Heat-Stress on Plant Ecophysiological Characteristics and Growth.

    Science.gov (United States)

    Wang, Dan; Heckathorn, Scott A; Mainali, Kumar; Tripathee, Rajan

    2016-01-01

    Heat-waves with higher intensity and frequency and longer durations are expected in the future due to global warming, which could have dramatic impacts in agriculture, economy and ecology. This field study examined how plant responded to heat-stress (HS) treatment at different timing in naturally occurring vegetation. HS treatment (5 days at 40.5°C) were applied to 12 1 m 2 plots in restored prairie vegetation dominated by a warm-season C 4 grass, Andropogon gerardii , and a warm-season C 3 forb, Solidago canadensis , at different growing stages. During and after each heat stress (HS) treatment, temperature were monitored for air, canopy, and soil; net CO 2 assimilation ( A net ), quantum yield of photosystem II (Φ PSII ), stomatal conductance ( g s ), and internal CO 2 level ( C i ), specific leaf area (SLA), and chlorophyll content of the dominant species were measured. One week after the last HS treatment, all plots were harvested and the biomass of above-ground tissue and flower weight of the two dominant species were determined. HS decreased physiological performance and growth for both species, with S. canadensis being affected more than A. gerardii , indicated by negative HS effect on both physiological and growth responses for S. canadensis . There were significant timing effect of HS on the two species, with greater reductions in the net photosynthetic rate and productivity occurred when HS was applied at later-growing season. The reduction in aboveground productivity in S. canadensis but not A. gerardii could have important implications for plant community structure by increasing the competitive advantage of A. gerardii in this grassland. The present experiment showed that HS, though ephemeral, may promote long-term effects on plant community structure, vegetation dynamics, biodiversity, and ecosystem functioning of terrestrial biomes when more frequent and severe HS occur in the future.

  4. Spatially Analyzing the Inequity of the Hong Kong Urban Heat Island by Socio-Demographic Characteristics

    Directory of Open Access Journals (Sweden)

    Man Sing Wong

    2016-03-01

    Full Text Available Recent studies have suggested that some disadvantaged socio-demographic groups face serious environmental-related inequities in Hong Kong due to the rising ambient urban temperatures. Identifying heat-vulnerable groups and locating areas of Surface Urban Heat Island (SUHI inequities is thus important for prioritizing interventions to mitigate death/illness rates from heat. This study addresses this problem by integrating methods of remote sensing retrieval, logistic regression modelling, and spatial autocorrelation. In this process, the SUHI effect was first estimated from the Land Surface Temperature (LST derived from a Landsat image. With the scale assimilated to the SUHI and socio-demographic data, a logistic regression model was consequently adopted to ascertain their relationships based on Hong Kong Tertiary Planning Units (TPUs. Lastly, inequity “hotspots” were derived using spatial autocorrelation methods. Results show that disadvantaged socio-demographic groups were significantly more prone to be exposed to an intense SUHI effect: over half of 287 TPUs characterized by age groups of 60+ years, secondary and matriculation education attainment, widowed, divorced and separated, low and middle incomes, and certain occupation groups of workers, have significant Odds Ratios (ORs larger than 1.2. It can be concluded that a clustering analysis stratified by age, income, educational attainment, marital status, and occupation is an effective way to detect the inequity hotspots of SUHI exposure. Additionally, inequities explored using income, marital status and occupation factors were more significant than the age and educational attainment in these areas. The derived maps and model can be further analyzed in urban/city planning, in order to mitigate the physical and social causes of the SUHI effect.

  5. Improvement of the decay heat removal characteristics of the generation IV gas-cooled fast reactor

    International Nuclear Information System (INIS)

    Epiney, A.S.

    2010-01-01

    Gas cooling in nuclear power plants (NPPs) has a long history, the corresponding reactor types developed in France, the UK and the US having been thermal neutron spectrum systems using graphite as the moderator. The majority of NPPs worldwide, however, are currently light water reactors, using ordinary water as both coolant and moderator. These NPPs - of the so-called second generation - will soon need replacement, and a third generation is now being made available, offering increased safety while still based on light water technology. For the longer-term future, viz. beyond the year 2030, R and D is currently ongoing on Generation IV NPPs, aimed at achieving closure of the nuclear fuel cycle, and hence both drastically improved utilization of fuel resources and minimization of long-lived radioactive wastes. Like the SFR, the GFR is an efficient breeder, also able to work as iso-breeder using simply natural uranium as feed and producing waste which is predominantly in the form of fission products. The main drawback of the GFR is the difficulty to evacuate decay heat following a loss-of-coolant accident (LOCA) due to the low thermal inertia of the core, as well as to the low coolant density. The present doctoral research focuses on the improvement of decay heat removal (DHR) for the Generation-IV GFR. The reference GFR system design considered in the thesis is the 2006 CEA concept, with a power of 2400 MWth. The CEA 2006 DHR strategy foresees, in all accidental cases (independent of the system pressure), that the reactor is shut down. For high pressure events, dedicated DHR loops with blowers and heat exchangers are designed to operate when the power conversion system cannot be used to provide acceptable core temperatures under natural convection conditions. For de-pressurized events, the strategy relies on a dedicated small containment (called the guard containment) providing an intermediate back-up pressure. The DHR blowers, designed to work under these pressure

  6. Improvement of the decay heat removal characteristics of the generation IV gas-cooled fast reactor

    International Nuclear Information System (INIS)

    Epiney, A. S.

    2010-09-01

    The majority of NPPs worldwide are currently light water reactors, using ordinary water as both coolant and moderator. (...) For the longer-term future, viz. beyond the year 2030, Research and Development is currently ongoing on Generation IV NPPs, aimed at achieving closure of the nuclear fuel cycle, and hence both drastically improved utilization of fuel resources and minimization of long-lived radioactive wastes. Since the very beginning of the international cooperation on Generation IV, viz. the year 2000, the main research interest in Europe as regards the advanced fast-spectrum systems needed for achieving complete fuel cycle closure, has been for the Sodium-cooled Fast Reactor (SFR). However, the Gas-cooled Fast Reactor (GFR) is currently considered as the main back-up solution. Like the SFR, the GFR is an efficient breeder, also able to work as iso-breeder using simply natural uranium as feed and producing waste which is predominantly in the form of fission products. The main drawback of the GFR is the difficulty to evacuate decay heat following a loss-of-coolant accident (LOCA) due to the low thermal inertia of the core, as well as to the low coolant density. The present doctoral research focuses on the improvement of decay heat removal (DHR) for the Generation-IV GFR. The reference GFR system design considered in the thesis is the 2006 CEA concept, with a power of 2400 MWth. The CEA 2006 DHR strategy foresees, in all accidental cases (independent of the system pressure), that the reactor is shut down. For high pressure events, dedicated DHR loops with blowers and heat exchangers are designed to operate when the power conversion system cannot be used to provide acceptable core temperatures under natural convection conditions. For depressurized events, the strategy relies on a dedicated small containment (called the guard containment) providing an intermediate back-up pressure. The DHR blowers, designed to work under these pressure conditions, need to be

  7. Physical properties and heat transfer characteristics of materials for krypton-85 storage

    International Nuclear Information System (INIS)

    Christensen, A.B.

    1977-09-01

    Krypton-85 decay results in heat generation, and the subsequent temperature increase in the krypton-85 storage media must be evaluated. This report compiles the physical properties of krypton and of potential krypton-85 storage materials which are required to calculate the maximum temperature developed during storage. Temperature calculations were made for krypton-85 stored as a gas or immobilized solid in steel storage cylinders. The effects of krypton-85 loading, cylinder radius, storage media properties, and exterior cooling on storage temperature were shown

  8. Effect of self-heating on electrical characteristics of AlGaN/ GaN HEMT on Si (111) substrate

    Science.gov (United States)

    Nigam, Adarsh; Bhat, Thirumaleshwara N.; Rajamani, Saravanan; Dolmanan, Surani Bin; Tripathy, Sudhiranjan; Kumar, Mahesh

    2017-08-01

    In order to study the effect of self-heating of AlGaN/ GaN high electron mobility transistors (HEMTs) characteristics fabricated on Si(111) substrate, simulations of 2DEG temperature on different drain voltages have been carried out by Sentaurus TCAD simulator tool. Prior to the electrical direct-current (DC) characteristics studies, structural properties of the HEMT structures were examined by scanning transmission electron microscopy. The comparative analysis of simulation and experimental data provided sheet carrier concentration, mobility, surface traps, electron density at 2DEG by considering factors such as high field saturation, tunneling and recombination models. Mobility, surface trap concentration and contact resistance were obtained by TCAD simulation and found out to be ˜1270cm2/Vs, ˜2×1013 cm-2 and ˜0.2 Ω.mm, respectively, which are in agreement with the experimental results. Consequently, simulated current-voltage characteristics of HEMTs are in good agreement with experimental results. The present simulator tool can be used to design new device structures for III-nitride technology.

  9. Effect of self-heating on electrical characteristics of AlGaN/ GaN HEMT on Si (111 substrate

    Directory of Open Access Journals (Sweden)

    Adarsh Nigam

    2017-08-01

    Full Text Available In order to study the effect of self-heating of AlGaN/ GaN high electron mobility transistors (HEMTs characteristics fabricated on Si(111 substrate, simulations of 2DEG temperature on different drain voltages have been carried out by Sentaurus TCAD simulator tool. Prior to the electrical direct-current (DC characteristics studies, structural properties of the HEMT structures were examined by scanning transmission electron microscopy. The comparative analysis of simulation and experimental data provided sheet carrier concentration, mobility, surface traps, electron density at 2DEG by considering factors such as high field saturation, tunneling and recombination models. Mobility, surface trap concentration and contact resistance were obtained by TCAD simulation and found out to be ∼1270cm2/Vs, ∼2×1013 cm-2 and ∼0.2 Ω.mm, respectively, which are in agreement with the experimental results. Consequently, simulated current-voltage characteristics of HEMTs are in good agreement with experimental results. The present simulator tool can be used to design new device structures for III-nitride technology.

  10. The stress characteristics of plate-fin structures at the different operation parameters of LNG heat exchanger

    Directory of Open Access Journals (Sweden)

    Ma Hongqiang

    2018-01-01

    Full Text Available In this paper, the stresses of plate-fin structures at the different operation parameters were analyzed in actual operation process of LNG plate-fin heat exchanger based on finite element method and thermal elastic theory. Stress characteristics of plate-fin structures were investigated at the different operation parameters of that. The results show that the structural failure of plate-fin structures is mainly induced by the maximum shear stress at the brazing filler metal layer between plate and fin while by the maximum normal stress in the region of brazed joint near the fin side. And a crack would initiate in brazed joint near the fin side. The maximum normal stress is also main factor to result in the structural failure of plate-fin structures at the different temperature difference (between Natural Gas (NG and Mixture Refrigerant (MR, MR temperature and NG pressure of LNG heat exchanger. At the same time, the peak stresses obviously increase as the temperature difference, MR temperature and NG pressure increase. These results will provide some constructive instructions in the safe operation of LNG plate-fin heat exchanger in a large-scale LNG cold-box.

  11. Contrastive experimental study on heat transfer and friction characteristics in steam cooled and air cooled rectangular channels with rib turbulators

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Jianying; Li, Guojun; Gao, Tieyu [Xian Jiaotong University, Xian (China)

    2014-09-15

    The present experiment compares the heat transfer and friction characteristics in steam cooled and air cooled rectangular channels (simulating a gas turbine blade cooling passage) with two opposite rib-roughened walls. The Reynolds number (Re) whose length scale is the hydraulic diameter of the passage is set within the range of 10000-60000. The channel length is 1000 mm. The pitch-to-rib height ratio, the channel aspect ratio and the channel blockage ratio is 10, 0.5 and 0.047, respectively. It is found that the average Nu, the average friction coefficient, and the heat transfer performance of both steam and air in the ribbed channels show almost the same change trend with the increase of Re. Under the same test conditions, the average Nu of steam is 30.2% higher than that of air, the average friction coefficient is 18.4% higher, and the heat transfer performances of steam on the ribbed and the smooth walls are 8.4% and 7.3% higher than those of air, respectively. In addition, semi-empirical correlations for the two test channels are developed, which can predict the Nu under the given test condition. The correlations can be used in the design of the internal cooling passage of new generation steam cooled gas turbine blade/vane.

  12. Effects of Heat Input on the Mechanical and Metallurgical Characteristics of Tig Welded Incoloy 800Ht Joints

    Directory of Open Access Journals (Sweden)

    Kumar S. Arun

    2017-09-01

    Full Text Available This study focuses on the effect of heat input on the quality characteristics of tungsten inert arc gas welded incoloy 800HT joints using inconel-82 filler wire. Butt welding was done on specimens with four different heat inputs by varying the process parameters like welding current and speed. The result indicated that higher heat input levels has led to the formation of coarser grain structure, reduced mechanical properties and sensitization issues on the weldments. The formation of titanium nitrides provided resistance to fracture and increased the tensile strength of the joints at high temperatures. Further aging was done on the welded sample at a temperature of 750°C for 500 hours and the metallographic result showed formation of carbides along the grain boundaries in a chain of discrete and globular form which increased the hardness of the material. The formation of spinel NiCr2O4 provided oxidation resistance to the material during elevated temperature service.

  13. Influence of malaxation time of olive paste on oil extraction yields and chemical and organoleptic characteristics of virgin olive oil obtained by a centrifugal decanter at water saving

    Directory of Open Access Journals (Sweden)

    Serraiocco, A.

    2002-06-01

    Full Text Available Experimental tests were carried out to ascertain the influence of malaxation time of olive paste on extraction yields and qualitative characteristics of virgin olive oils obtained by a centrifugal decanter at water saving. Results show that malaxation time has to be no less than 45 minutes to have a satisfactory oil extraction yield. Furthermore, it was ascertained that the malaxation time, protracted up to 90 minutes, does not have influence upon qualitative and organoleptic characteristics of oils. Only the total phenols content of oils changed significantly when the malaxation time of olive paste increased from 15 to 90 minutes. However, in this research has been demonstrated that in some cases the total phenols content of oils increased during the first 30-45 minutes of malaxation and after it diminished. This is due to the variation of total phenols content of vegetable water that in the first time increased and after diminished very quickly. Because of the partition equilibrium law, the total phenols content of oil changed in the same way. Finally, results show that the composition of volatile substances of head-space of oils did not change increasing the malaxation time of olive paste obtained from good quality olive fruits.Se realizaron pruebas experimentales para verificar la influencia del tiempo de batido sobre los rendimientos en aceite y sobre las características de la calidad de los aceites obtenidos con un decanter centrifugo con ahorro de agua. Los resultados conseguidos indicaron que el tiempo de batido no debe ser inferior a 45 minutos para poder obtener rendimientos en aceite satisfactorios. Además, se pudo verificar que la operación de batido, aun siendo prolongada a 90 minutos, no influencia significativamente en las características cualitativas y organolépticas de los aceites. Solo el contenido de fenoles totales en los aceites disminuyó cuando el tiempo de batido fue incrementado de 15 a 90 minutos. Sin embargo, se

  14. Heat-Transfer characteristics of Supercritical Water flowing upward in bare-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Sidawi, K., E-mail: khalil.sidawi@uoit.ca [University of Ontario Institute of Technology, Faculty of Energy Systems and Nuclear Sciences, Oshawa, ON (Canada)

    2015-07-01

    There has been many correlations developed for Supercritical Water (SCW) flowing in bare-tubes. These correlations, generally, have limits based on the experimental trials. However, this does not indicate the true range to which these correlations can be applied. Furthermore, increases in heat flux and decreases in mass flux have been known to lead to Deteriorated Heat-Transfer (DHT). One way to classify fluids in the supercritical region is to use the Eckert Number to differentiate between two different sub-states{sup 1} ; when T < T{sub pc}, SCW is considered to be liquid-like, whereas at T > T{sub pc}, SCW is considered to be gas-like. There is a significant decrease in RMS error for calculated HTC in trials where there is a single sub-state across the cross-section. Trials where there is a combination of sub-states have drastically higher RMS error for HTC. Furthermore, some trials indicate a decrease in HTC at the interphase between the two sub-states. (author)

  15. Off-gas characteristics of defense waste vitrification using liquid-fed Joule-heated ceramic melters

    International Nuclear Information System (INIS)

    Goles, R.W.; Sevigny, G.J.

    1983-09-01

    Off-gas and effluent characterization studies have been established as part of a PNL Liquid-Fed Ceramic Melter development program supporting the Savannah River Laboratory Defense Waste Processing Facility (SRL-DWPF). The objectives of these studies were to characterize the gaseous and airborne emission properties of liquid-fed joule-heated melters as a function of melter operational parameters and feed composition. All areas of off-gas interest and concern including effluent characterization, emission control, flow rate behavior and corrosion effects have been studied using alkaline and formic-acid based feed compositions. In addition, the behavioral patterns of gaseous emissions, the characteristics of melter-generated aerosols and the nature and magnitude of melter effluent losses have been established under a variety of feeding conditions with and without the use of auxiliary plenum heaters. The results of these studies have shown that particulate emissions are responsible for most radiologically important melter effluent losses. Melter-generated gases have been found to be potentially flammable as well as corrosive. Hydrogen and carbon monoxide present the greatest flammability hazard of the combustibles produced. Melter emissions of acidic volatile compounds of sulfur and the halogens have been responsible for extensive corrosion observed in melter plenums and in associated off-gas lines and processing equipment. The use of auxiliary plenum heating has had little effect upon melter off-gas characteristics other than reducing the concentrations of combustibles

  16. The effect of air permeability characteristics of protective garments on the induced physiological strain under exercise-heat stress.

    Science.gov (United States)

    Epstein, Yoram; Heled, Yuval; Ketko, Itay; Muginshtein, Jeni; Yanovich, Ran; Druyan, Amit; Moran, Daniel S

    2013-08-01

    The high values of thermal resistance (Rct) and/or vapor resistance (Ret) of chemical protective clothing (CPC) induce a considerable thermal stress. The present study compared the physiological strain induced by CPCs and evaluates the relative importance of the fabrics' Rct, Ret, and air permeability in determining heat strain. Twelve young (20-30 years) healthy, heat-acclimated male subjects were exposed fully encapsulated for 3h daily to an exercise-heat stress (35°C and 30% relative humidity, walking on a motor-driven treadmill at a pace of 5 km h(1) and a 4% inclination, in a work-rest cycle of 45 min work and 15 min rest). Two bipack CPCs (PC1 and PC2) were tested and the results were compared with those attained by two control suits-a standard cotton military BDU (CO1) and an impermeable material suit (CO2). The physiological burden imposed by the two bilayer garments was within the boundaries set by the control conditions. Overall, PC2 induced a lower strain, which was closer to CO1, whereas PC1 was closer to CO2. Air permeability of the PC2 cloth was almost three times higher than that of PC1, enabling a better heat dissipation and consequently a lower physiological strain. Furthermore, air permeability characteristic of the fabrics, which is associated with its construction and weave, significantly correlated with the physiological strain, whereas the correlation with Rct, Ret, and weight was poor. The results emphasize the importance of air permeability in reducing the physiological strain induced by CPCs.

  17. Design of a natural draft air-cooled condenser and its heat transfer characteristics in the passive residual heat removal system for 10 MW molten salt reactor experiment

    International Nuclear Information System (INIS)

    Zhao, Hangbin; Yan, Changqi; Sun, Licheng; Zhao, Kaibin; Fa, Dan

    2015-01-01

    As one of the Generation IV reactors, Molten Salt Reactor (MSR) has its superiorities in satisfying the requirements on safety. In order to improve its inherent safety, a concept of passive residual heat removal system (PRHRS) for the 10 MW Molten Salt Reactor Experiment (MSRE) was put forward, which mainly consisted of a fuel drain tank, a feed water tank and a natural draft air-cooled condenser (NDACC). Besides, several valves and pipes are also included in the PRHRS. A NDACC for the PRHRS was preliminarily designed in this paper, which contained a finned tube bundle and a chimney. The tube bundle was installed at the bottom of the chimney for increasing the velocity of the air across the bundle. The heat transfer characteristics of the NDACC were investigated by developing a model of the PRHRS using C++ code. The effects of the environmental temperature, finned tube number and chimney height on heat removal capacity of the NDACC were analyzed. The results show that it has sufficient heat removal capacity to meet the requirements of the residual heat removal for MSRE. The effects of these three factors are obvious. With the decay heat reducing, the heat dissipation power declines after a short-time rise in the beginning. The operation of the NDACC is completely automatic without the need of any external power, resulting in a high safety and reliability of the reactor, especially once the accident of power lost occurs to the power plant. - Highlights: • A model to study the heat transfer characteristics of the NDACC was developed. • The NDACC