WorldWideScience

Sample records for finned tube performance

  1. Performance of tubes-and plate fins heat exchangers

    International Nuclear Information System (INIS)

    By means of a two-dimensional analysis performance, and using local heat transfer coefficients, the plate fin temperature distribution, the air bulk temperature along the stream path and the fin efficiency can be obtained, for several Reynolds numbers and fin materials. Herein are also presented the average heat transfer coefficients for isothermal plate fins, referring to heat exchangers with central-tube and rear-tube row and to two-row tubes heat exchangers configurations. It is possible to obtain the real tax or the real area of heat transfer, using the average hea transfer coefficients for isothermal plate fins and the fin efficiency. (Author)

  2. A Review: Fin and Tube Heat Exchanger Performance with different Fin Pattern

    Directory of Open Access Journals (Sweden)

    S D Katkade

    2014-12-01

    Full Text Available Various methods are used to increase rate of heat transfer without affecting much the overall performance of the system. These techniques are used in heat exchangers. Heat exchangers are used in various applications in day to day life. Some of the applications of heat exchangers are-in process industries, thermal Power plants, airconditioning equipments, refrigerators, radiators for space vehicles, automobiles etc. The present paper is a review of the various methods used to increase the heat transfer performance by using different types of fins. The performance of different fin types is evaluated at different Reynolds number, fin pitch, number of tube rows etc.

  3. Performance Evaluation of Plate-Fin-And Tube Heat Exchanger with Wavy Fins- A Review

    Directory of Open Access Journals (Sweden)

    Sandip S. Kale

    2014-09-01

    Full Text Available The plate fin-and-tube heat exchangers are widely used in variety of industrial applications, particularly in the heating, air-conditioning and refrigeration, HVAC industries. In most cases the working fluid is liquid on the tube side exchanging heat with a gas, usually air. It is seen that the performance of heat exchangers can be greatly increased with the use of unconventionally shaped flow passages such as plain, perforated offset strip, louvered, wavy, vortex generator and pin. The current study is focused on wavy-fin. The wavy surface can lengthen the path of airflow and cause better airflow mixing. In order to design better heat exchangers and come up with efficient designs, a thorough understanding of the flow of air in these channels is required. Hence this study focuses on the heat transfer and friction characteristics of the air side for wavy fin and tube heat exchanger.

  4. Effect of fin pitch and number of tube rows on the air side performance of herringbone wavy fin and tube heat exchangers

    International Nuclear Information System (INIS)

    An experimental study is conducted to investigate the effects of a fin pitch and number of tube rows on the air side performance of fin and tube heat exchangers having herringbone wavy fin configuration at various fin thicknesses. A total of 10 samples of fin and tube heat exchanger with a tube outside diameter of 9.53mm, transverse tube pitch of 25.4mm and longitudinal tube pitch of 19.05mm, having various fin pitches, number of tube rows and fin thicknesses, are tested in a well insulated open wind tunnel. The heat exchangers are made from aluminium plate finned, copper tube. Ambient air is used as a working fluid in the air side while hot water is used for the tube side. The results are presented as the variation of the Colburn factor and the friction factor with the Reynolds number based on the fin collar outside diameter (ReDc). The experimental results reveal that the fin pitch has an insignificant effect on the heat transfer characteristic. The friction factor increases with increasing fin pitch when ReDc>2500, approximately. The Colburn factor and the friction factor decrease with increasing number of tube rows when ReDc<4000, approximately. These results remain the same when the fin thickness is changed

  5. Fin-and-tube condenser performance evaluation using neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Ling-Xiao [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); Zhang, Chun-Lu [China R and D Center, Carrier Corporation, No. 3239 Shen Jiang Road, Shanghai 201206 (China)

    2010-05-15

    The paper presents neural network approach to performance evaluation of the fin-and-tube air-cooled condensers which are widely used in air-conditioning and refrigeration systems. Inputs of the neural network include refrigerant and air-flow rates, refrigerant inlet temperature and saturated temperature, and entering air dry-bulb temperature. Outputs of the neural network consist of the heating capacity and the pressure drops on both refrigerant and air sides. The multi-input multi-output (MIMO) neural network is separated into multi-input single-output (MISO) neural networks for training. Afterwards, the trained MISO neural networks are combined into a MIMO neural network, which indicates that the number of training data sets is determined by the biggest MISO neural network not the whole MIMO network. Compared with a validated first-principle model, the standard deviations of neural network models are less than 1.9%, and all errors fall into {+-}5%. (author)

  6. Study on turbulent flow and heat transfer performance of tubes with internal fins in EGR cooler

    Science.gov (United States)

    Liu, Lin; Ling, Xiang; Peng, Hao

    2015-01-01

    In this paper, flow and heat transfer performances of the tubes with internal longitudinal fins in Exhaust Gas Recirculation (EGR ) cooler were investigated by three-dimension computation and experiment . Each test tube was a single-pipe structure, without inner tube. Three-dimension computation was performed to determine the thermal characteristics difference between the two kinds of tubes, that is, the tube with an inner solid staff as a blocked structure and the tube without the blocked structure. The effects of fin width and fin height on heat transfer and flow are examined. For proving the validity of numerical method, the calculated results were compared with corresponding experimental data. The tube-side friction factor and heat transfer coefficient were examined. As a result, the maximum deviations between the numerical results and the experimental data are approximately 5.4 % for friction factor and 8.6 % for heat transfer coefficient, respectively. It is found that two types of internally finned tubes enhance significantly heat transfer. The heat transfer of the tube with blocked structure is better, while the pressure drop of the tube without blocked structure is lower. The comprehensive performance of the unblocked tube is better to applied in EGR cooler.

  7. Performance of residential air-conditioning systems with flow maldistribution in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Brix, Wiebke

    2011-01-01

    Refrigerant and airflow maldistribution in fin-and-tube evaporators for residential air-conditioning was investigated with numerical modeling. Fin-and-tube heat exchangers usually have a pre-defined circuitry. However, the objective in this study was to perform a generic investigation of each individual maldistribution source in an independent manner. Therefore, the evaporator and the condenser were simplified to be straight tubes for the purposes of this study. The numerical model of the R410A system, its verification and an investigation of individual maldistribution sources are presented in this paper. The maldistribution sources of interest were: inlet liquid/vapor phase distribution, feeder tube bending and airflow distribution. The results show that maldistribution reduced the cooling capacity and the coefficient of performance of the system. In particular, different phase distribution and non-uniform airflow distribution reduced the performance significantly. Different feeder tube bendings only caused a minor decrease in performance.

  8. Thermal performance of a spirally coiled finned tube heat exchanger under wet-surface conditions

    International Nuclear Information System (INIS)

    This paper is a continuation of the author's previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data

  9. An experimental investigation on air-side performances of finned tube heat exchangers for indirect air-cooling tower

    Directory of Open Access Journals (Sweden)

    Du Xueping

    2014-01-01

    Full Text Available A tremendous quantity of water can be saved if the air cooling system is used, comparing with the ordinary water-cooling technology. In this study, two kinds of finned tube heat exchangers in an indirect air-cooling tower are experimentally studied, which are a plain finned oval-tube heat exchanger and a wavy-finned flat-tube heat exchanger in a cross flow of air. Four different air inlet angles (90°, 60 °, 45°, and 30° are tested separately to obtain the heat transfer and resistance performance. Then the air-side experimental correlations of the Nusselt number and friction factor are acquired. The comprehensive heat transfer performances for two finned tube heat exchangers under four air inlet angles are compared. For the plain finned oval-tube heat exchanger, the vertical angle (90° has the worst performance while 45° and 30° has the best performance at small ReDc and at large ReDc, respectively. For the wavy-finned flat-tube heat exchanger, the worst performance occurred at 60°, while the best performance occurred at 45° and 90° at small ReDc and at large ReDc, respectively. From the comparative results, it can be found that the air inlet angle has completely different effects on the comprehensive heat transfer performance for the heat exchangers with different structures.

  10. A comparison of the heat transfer and pressure drop performance of R-134a-lubricant mixtures in different diameter smooth tubes and micro-fin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Eckels, S.J. [Kansas State Univ., Manhattan, KS (United States). Dept. of Mechanical Engineering; Doerr, T.M.; Pate, M.B. [Iowa State Univ., Ames, IA (United States). Mechanical Engineering Dept.

    1998-10-01

    The average heat transfer coefficients and pressure drops during evaporation and condensation are reported for mixtures of R-134a and an ester lubricant in tubes of 12.7 mm (1/2 in.) outer diameter. The objective of this paper is to evaluate the performance of the R-134a-lubricant mixtures in these tubes and determine the performance benefits of the micro-fin tube. The performance benefits of the tubes with 12.7 mm (1/2 in.) outer diameter are compared to those of smaller tubes with 9.52 mm (3/8 in.) outer diameter. The lubricant used was a 169 SUS penta erythritol ester mixed-acid lubricant. The lubricant concentration was varied from 0--5.1% in the mixture. The average heat transfer coefficients in the 12.7 mm (1/2 in.) micro-fin tube were 50--150% higher than those for the 12.7 mm (1/2 in.) smooth tube, while pressure drops in the micro-fin tube were 5% to 50% higher than in the smooth tube. The addition of lubricant degraded the average heat transfer coefficients in all cases except during evaporation at low lubricant concentrations. Pressure drops were always increased with the addition of lubricant. The experimental results also indicate that tube diameter has some effect on the performance benefits of the micro-fin tube over that of the smooth tube.

  11. Three-dimensional performance analysis of plain fin tube heat exchangers in transitional regime

    International Nuclear Information System (INIS)

    Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of a four-row plain fin-and-tube heat exchanger using the Commercial Computational Fluid Dynamics Code ANSYS CFX 12.0. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 400 to 2000. Fluid flow and heat transfer are simulated and results compared using both laminar and turbulent flow models (k-?) with steady and incompressible fluid flow. Model validation is carried out by comparing the simulated case friction factor (f) and Colburn factor (j) with the experimental data of Wang et al.. Reasonable agreement is found between the simulations and experimental data. In this study the effect of geometrical parameters such as fin pitch, longitudinal pitch and transverse pitch of tube spacing are studied. Results are presented in the form of friction factor (f) and Colburn factor (j). For both laminar and transitional flow conditions heat transfer and friction factor decrease with the increase of longitudinal and transverse pitches of tube spacing whereas they increase with fin pitches for both in-line and staggered configurations. Efficiency index increases with the increase of longitudinal and transverse pitches of tube spacing but decreases with increase of fin pitches. For a particular Reynolds number, the efficiency index is higher in in-line arrangement than the staggered case. - Highlights: t than the staggered case. - Highlights: ? 3D CFD simulations for plain-fin-and-tube heat exchanger. ? Validated with experimental data. ? Parametric study for the effects of fluid flow and heat transfer.

  12. Effect of refrigerant mal-distribution in fin-and-tube evaporators on system performance

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    Refrigerant mal-distribution in fin-and-tube evaporators for residential air-conditioning (RAC) is investigated numerically in this paper. A model of the system is developed in the object-oriented modeling language Modelica. Themodels of the compressor and expansion valve are static, whereas the condenser is a dynamic moving boundary model. The evaporator model is a dynamic distributed one-dimensional homogeneous equilibrium model, in order to capture the distribution phenomena. Fin-and-tube heat exchangers usually have a complex circuitry, however the evaporator will be simplified to be two straight tubes. The refrigerant mal-distribution is then induced to the evaporator by varying the vapor quality at the inlet to each feeder tube, the pressure drop through each feeder tube and the air-flow across each tube. Finally it is shown that air-flow mal-distribution can be compensated by an intelligent distributor, that ensures equal superheat in both tubes. The refrigerant is R410a.

  13. Comparison of heat pump performance using fin-and-tube and microchannel heat exchangers under frost conditions

    International Nuclear Information System (INIS)

    Vapor compression heat pumps are drawing more attention in energy saving applications. Microchannel heat exchangers can provide higher performance via less core volume and reduce system refrigerant charge, but little is known about their performance in heat pump systems under frosting conditions. In this study, the system performance of a commercial heat pump using microchannel heat exchangers as evaporator is compared with that using conventional finned-tube heat exchangers numerically and experimentally. The microchannel and finned-tube heat pump system models used for comparison of the microchannel and finned-tube evaporator performance under frosting conditions were developed, considering the effect of maldistribution on both refrigerant and air sides. The quasi-steady-state modeling results are in reasonable agreement with the test data under frost conditions. The refrigerant-side maldistribution is found remarkable impact on the microchannel heat pump system performance under the frost conditions. Parametric study on the fan speed and the fin density under frost conditions are conducted as well to figure out the best trade-off in the design of frost tolerant evaporators. (author)

  14. Structure optimization and performance experiments of a solar-powered finned-tube adsorption refrigeration system

    International Nuclear Information System (INIS)

    Highlights: • New-structure finned-tube adsorption bed for enhancing heat and mass transfer. • Temperatures on different parts of the adsorption tubes differ little. • Maximum COP of 0.122 and maximum daily ice-making of 6.5 kg are achieved by experiments. • Cooling efficiency of system with valve control higher than that without valve control. - Abstract: A large-diameter aluminum-alloy finned-tube absorbent bed collector was designed and optimized by enhancing the heat and mass transfer in the collector. The collection efficiency of the adsorbent bed collector was between 31.64% and 42.7%, and the temperature distribution in the absorbent bed was relatively uniform, beneficial to adsorption/desorption of the adsorbate in the absorbent bed. A solar-powered solid adsorption refrigeration system with the finned-tube absorbent bed collector was built. Some experiments corresponding to the adsorption/desorption process with and without a valve control were conducted in four typical weather conditions: sunny with clear sky, sunny with partly cloudy sky, cloudy sky and overcast sky. Activated carbon–methanol was utilized as the working pair for adsorption refrigeration in the experiments. The experiments achieved the maximum COP of 0.122 and the maximum daily ice-making of 6.5 kg. Under the weather conditions of sunny with clear sky, sunny with partly cloudy sky, and cloudy sky, ice-making phenomenon were observed. Even in the overcast-sky weather condition, the cooling efficiency of the system still reached 0.039 when the total solar radiation was 11.51 MJ. The cooling efficiency of the solar-powered adsorption refrigeration system with a valve control in the adsorption/desorption process was significantly higher than that without a valve control

  15. Fin Distance Effect at Tube-Fin Heat Exchanger

    Science.gov (United States)

    Lemfeld, F.; Muller, M.; Frana, K.

    2013-04-01

    Article deals with numerical simulation of the Tube-Fin heat exchanger. Several distances between fins are examined with intence of increasing the cooling output of the heat exchanger. Geometrical model consists of set of 2 fins with input and output area. Calculations covers the area of the gap from 2.25 mm to 4 mm with new fin geometry. For the numerical silumation was used software Ansys Fluent.

  16. Cycle performance of alternative refrigerants for domestic air-conditioning system based on a small finned tube heat exchanger

    International Nuclear Information System (INIS)

    In order to find alternative refrigerants which exhibit both favorable cycle performance and environmental friendliness, R32 and R290 were utilized to contrast to R22 and R410A as substitutes in the present study. The experiments were conducted with a 5 mm finned tube heat exchanger based on the enthalpy method in a small split household air conditioner. The results showed that in nominal cooling conditions, the COPR of R32 and R290 were 26.8% and 20.4% higher than R22, 7.3% and 2.1% higher than R410A. And in nominal heating conditions, the COPHR of R32 and R290 were both 11.0% higher than R22, 5.3% higher than R410A. The systems with R290 and R32 have similar capacities to that with R22 and R410A in heating mode, but a relatively huge difference of capacities in cooling mode. In consideration of charge amount, R290 could be considered as the most superior alternative refrigerant in air conditioners with the small finned tube heat exchanger. - Highlights: •Comparisons are made in the air conditioner system based on 5 mm tube fin heat exchanger. •The R22 system has a similar performance to others in heating mode while a huge difference in cooling mode. •The optimal charge of R290 is reduced with nearly no decline in the capacity and COP. •SLHX is attached to the system of R290 and successfully promote safety and capacity. •Heat loads are taken into account to evaluate the advantages and disadvantages of R290 and R32

  17. Investigation of contact resistance for fin-tube heat exchanger by means of tube expansion

    Science.gov (United States)

    Hing, Yau Kar; Raghavan, Vijay R.; Meng, Chin Wai

    2012-06-01

    An experimental study on the heat transfer performance of a fin-tube heat exchanger due to mechanical expansion of the tube by bullets has been reported in this paper. The manufacture of a fin-tube heat exchanger commonly involves inserting copper tubes into a stack of aluminium fins and expanding the tubes mechanically. The mechanical expansion is achieved by inserting a steel bullet through the tube. The steel bullet has a larger diameter than the tube and the expansion provides a firm surface contact between fins and tubes. Five bullet expansion ratios (i.e. 1.045 to 1.059) have been used in the study to expand a 9.52mm diameter tubes in a fin-tube heat exchanger. The study is conducted on a water-to-water loop experiment rig under steady state conditions. In addition, the effects of fin hardness and fin pitch are investigated in the study. The results indicate that the optimum heat transfer occurred at a bullet expansion ratio ranging from 1.049 to 1.052. It is also observed that larger fin pitches require larger bullet expansion ratios, especially with lower fin hardness. As the fin pitch increases, both fin hardness (i.e. H22 and H24) exhibit increasing heat transfer rate per fin (W/fin). With the H22 hardness temper, the increase is as much as 11% while H24 increases by 1.2%.

  18. CFD Analysis of Plate Fin Tube Heat Exchanger for Various Fin Inclinations

    OpenAIRE

    Subodh Bahirat,; Joshi, P. V.

    2014-01-01

    ANSYS Fluent software is used for three dimensional CFD simulations to investigate heat transfer and fluid flow characteristics of six different fin angles with plain fin tube heat exchangers. The numerical simulation of the fin tube heat exchanger was performed by using a three dimensional numerical computation technique. Geometry of model is created and meshed by using ANSYS Workbench software. To solve the equation for the fluid flow and heat transfer analysis ANSYS FLUENT ...

  19. Impact of delta winglet vortex generators on the performance of a novel fin-tube surfaces with two rows of tubes in different diameters

    International Nuclear Information System (INIS)

    Highlights: ? Two novel fin-tube surfaces are presented and numerically simulated. ? The novel fin-tube surfaces bring about heat transfer enhancement. ? Pressure drop reduction of the novel design is another interesting finding. - Abstract: To achieve heat transfer enhancement and lower pressure loss penalty, even pressure loss reduction, two novel fin-tube surface with two rows of tubes in different diameters are presented in this paper. Numerical simulation results show that the fin-tube surface with first row tube in smaller size and second row tube in larger size can lead to an increase of heat transfer and decrease of pressure drop in comparison with the traditional fin-tube surface with two rows of tubes in the same size. Based on this understanding, delta winglet pairs are punched out only from the larger fin area around the first transverse row of tubes in smaller size in the novel fin-tube surfaces. Delta winglet pairs used as longitudinal vortex generator are arranged either in 'common flow up' or 'common flow down' configurations. Numerical simulation results show that delta winglet pairs can bring about a further heat transfer enhancement and pressure drop decrease through the careful arrangement of the location, size and attack angle of delta winglet pairs either in 'common flow up' or 'common flow down' configurations. The traditional knowledge of heat transfer enhancement with necessary pressure drop increase is challenged by the present conclusis challenged by the present conclusion. The present work will be helpful to develop more compact, higher heat transfer efficiency, lower fan power and quieter heat exchanger of refrigeration and air condition system.

  20. PHASE CHANGE AROUND A FINNED TUBE

    Directory of Open Access Journals (Sweden)

    Aytunç EREK

    2003-01-01

    Full Text Available This study presents the heat transfer enhancement in the thermal energy storage system by using radially finned tube. The solution of the system consists of the solving the equations of the heat transfer fluid (HTF, the pipe wall and fin, and the phase change material (PCM as one domain. The control volume finite difference approach and the semi implicit solver (SIS are used to solve the equations. Fully developed velocity distribution is taken in the HTF. Flow parameters (Re number and inlet temperature of coolant and fin parameters (the number of fins, fin length, fin thickness are found to influence solidification fronts and the total stored energy.

  1. Laminar heat transfer characteristics of internally finned tube with sinusoidal wavy fin

    Science.gov (United States)

    Lin, M.; Tian, L.; Wang, Q. W.

    2011-06-01

    Comparative numerical study of laminar heat transfer characteristics of annular tubes with sinusoidal wavy fins has been conducted both experimentally and numerically with Re = 299-1,475. The uniform heat flux is imposed on the tube outside wall surface. Two tube materials (copper and stainless steel) are considered. It is found that the fluid temperature profile is not linear but convex along the flow direction due to the axial heat conduction in tube wall, and the effects of axial heat conduction on the heat transfer decreases with an increase in Reynolds number or decrease in tube wall thermal conductivity. The axial distributions of local Nusselt number could reach periodically fully developed after 3-5 cycles. The convectional data reduction method based on the traditional method should be improved for tube with high thermal conductivity or low Reynolds numbers, Otherwise, the heat transfer performance of internally finned tube may be underestimated.

  2. Full analysis of low finned tube heat exchangers

    International Nuclear Information System (INIS)

    In this paper, first the governing parameters characterizing low-finned tubes are reviewed. Second, the more important of the available performance correlations are compared with the available experimental data. The most reliable one can be employed to develop a pressure drop relationship, which has already been used in an algorithm for exchanger sizing. Also a means for the identification of advantages of low-finned tube heat exchangers over plain tube units has been developed. It has been recognized that for low-finned tube units there are some potential benefits to place certain liquids, particularly with high viscosities, in the shell side of heat exchangers rather than the tube side. These benefits can be obtained in both reduction of surface area and the number of shells required for a given duty. They result in heat exchangers, which are more compact and are also easier to construct. The performance evaluation of low-finned units, in terms of area benefits is not discussed in this paper. However, the results of this study will complete the author's investigation for low-finned tubes heat exchangers

  3. Enhance heat transfer for PCM melting in triplex tube with internal–external fins

    International Nuclear Information System (INIS)

    Highlights: • Three heating methods were applied to melt the PCM in TTHX without fin. • Heat transfer enhanced by using fin to inner, middle tubes, and both tubes. • Performances of TTHX with fin were compared with finned, internally finned tube. - Abstract: Thermal energy storage is critical for eliminating the discrepancy between energy supply and demand as well as for improving the efficiency of solar energy systems. This study numerically investigates the melting process in a triplex-tube heat exchanger with phase-change material (PCM) RT82. A two-dimensional numerical model is developed using the Fluent 6.3.26 software program. Three heating methods were used to melt the PCM from the inside tube, outside tube, and both tubes. Internal, external, and internal–external fin enhancement techniques were studied to improve the heat transfer between the PCM and heat transfer fluid. Enhancement techniques were compared with the inside tube heating, outside tube heating, both tube heating as well as the finned and internally finned tube. The effects of fin length on the enhancement techniques were investigated. Using a triplex-tube heat exchanger with internal–external fins, predicted results indicated that melting time is reduced to 43.3% in the triplex tube without fins. Experiments were conducted to validate the proposed model. Simulated results correspond with the experimental results

  4. CFD Analysis of Plate Fin Tube Heat Exchanger for Various Fin Inclinations

    Directory of Open Access Journals (Sweden)

    Subodh Bahirat,

    2014-08-01

    Full Text Available ANSYS Fluent software is used for three dimensional CFD simulations to investigate heat transfer and fluid flow characteristics of six different fin angles with plain fin tube heat exchangers. The numerical simulation of the fin tube heat exchanger was performed by using a three dimensional numerical computation technique. Geometry of model is created and meshed by using ANSYS Workbench software. To solve the equation for the fluid flow and heat transfer analysis ANSYS FLUENT was used in the fin-tube heat exchanger. The fluid flow and heat transfer are simulated and result compared for both laminar and turbulent flow models k-epsilon and SST k-omega, with steady state solvers to calculate heat transfer, flow velocity and temperature fields of variable inclined fin angles (? = 00 ,100 , 200 , 300 , 400 ,500 . Model is validate by comparing the simulated value of velocity, temperature and colburn factor with experimental and numerical results investigated by WANG [1] and GHORI KIRAR [10]. Reasonable agreement is found between the simulations and other results, and the ANSYS Fluent software is sufficient for simulating the flow fields in tube fin heat exchanger.

  5. Eddy current test of fin tubes for a heat exchanger

    International Nuclear Information System (INIS)

    Eddy current probes were designed for the test of fin tubes. Fin tubes, often used for heat exchangers, have uneven outer and inner surfaces to enhance the heat emission. The surface roughness make it difficult to detect flaws employing eddy current test(ECT). In order to overcome the difficulties we performed two types of works, one is the delopment of ECT probes, and the other is the signal processing including fast Fourier transform and digital filtering. In the development of ECT probes, we adopted empirical design method. Our ECT probes for fin tubes are inside diameter type. And we are specially concerned about geometric features such as the widths of the coils composing an ECT probe. We fabricated four probes with various coil widths. Eddy current test was performed using those ECT probes on specimens with artificial flaws. After analyzing the output signals, we found that, in order for the effective testing, the width of a coil should be determined considering the pitch of the fins of a tube. And we also learned that the frequency filtering could improve the s/n ratio.

  6. Tube an fin assembly exchangers in power plants

    International Nuclear Information System (INIS)

    This patent describes a fin and tube assembly for use in a heat exchanger. It comprises: a steel tube provided with an external coating of aluminum; and at least one aluminum fin having aluminum braze cladding in contact with and brazed to the tube. The assembly being characterized by the absence of any appreciable exposed layer of ferrous-aluminum intermetallic compound or intermediate phase on the exterior of the tube in the area of the fin

  7. Transfer coefficients for plate fin and elliptical tube heat exchangers

    International Nuclear Information System (INIS)

    In order to determine transfer coefficients for plate fin and elliptical tube exchangers, mass transfer experiments have been performed using the naphthalene sublimation technique. By means of the heat-mass transfer analogy, the results can be converted to heat transfer results. The transfer coefficients were compared with those for circular tube exchangers and the comparison revealed no major differences. This is a positive outcome, since the use of elliptical tubes may reduce substantially the pressure drop, without affecting the transfer characteristics.(Author)

  8. Thermal Analysis of Fin and Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Ms N. B. Rairker

    2014-06-01

    Full Text Available This paper studied experimentally the effect of heat transfer of fin and tube type heat exchanger for different mass flow rate of fluid. The thermal stresses induced on fin and tube is also studied by ansys software at steady state condition by changing the width of fin and diameter of tube. Readings were taken experimentally by changing mass flow rate of fluid at respective temperatures. Comparison was done on theoretically and experimentally obtained results. It is observed that as the width of fin increases thermal stresses on fin also increases. Likewise for tube, by varying diameter of tube different values of stress are obtained. It is also observed at full valve position maximum thermal stresses are induced on fin as well as tube.

  9. Effect of the Moments of Probability Density Function for Non-uniform Air Flow Distribution on the Hydraulic Performance of a Fin-tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Wai Meng Chin

    2011-01-01

    Full Text Available The work presented in this paper examines the effect of a non-uniform airflow velocity distribution on the air pressure drop through the fin passages of a single row fin-tube heat exchanger. Water flow rate through the tubes and its temperature are taken as constant. Maldistribution of the airflow increases the average pressure drop with respect to that of a uniform flow. As a result of this, the pumping power required by the fan or blower will also increase. The increase of the pumping power is calculated by means of a discretization technique and it is analyzed with respect to the non-uniform distribution statistical moments of probability density function, i.e., the mean, standard deviation, skew and kurtosis. The analysis reveals that the increase of pumping power is dependent on the exchanger NTU, standard deviation and skew of the velocity distribution. Kurtosis has no effect on the pressure drop. Correlations have been developed to predict this increase of pumping power from known statistical moments and resulting air temperatures. These can then be used as design tools to optimize the sizing of the heat exchanger within the air-conditioning unit, hence giving the best energy efficiency performance.

  10. Impact of air and refrigerant maldistributions on the performance of finned-tube evaporators with R-22 and R-407C. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jangho; Domanski, P.A. [Department of Commerce, Gaithersburg, MD (United States)

    1997-07-01

    The report presents basic features of the evaporator model, EVAP5M, and simulation results for an evaporator operating with R-22 and R-407C at non-uniform air and refrigerant distributions. EVAP5M was developed under this project to provide a tool for simulating a finned-tube air-to refrigerant evaporator operating with single-component refrigerants and refrigerant mixtures. The tube-by-tube modeling approach allowed for one-dimensional non-uniformity in the air velocity profile and arbitrary maldistribution on the refrigerant side. The model uses the Carnahan-Starling-DeSantis equation of state for calculating refrigerant thermodynamic properties. Simulations were performed for three evaporator slabs with different refrigerant circuitry designs. For the maldistributions studied, maldistributed air caused much more significant capacity degradation than maldistributed refrigerant. In some cases capacity decreased to as low as 57 percent of the value obtained for uniform velocity profile. Simulation results showed that R-22 and R-407C have similar susceptibility to capacity degradation. Relative change of capacity varied depending on the evaporator design and maldistribution studied. 17 refs., 18 figs., 9 tabs.

  11. Pressure loss and heat transfer studies performed on axial-flow finned-tube bundle heat exchangers

    International Nuclear Information System (INIS)

    The experimental studies intend to determine the dependence on the parameters of influence state of flow, tube length, and bundle pitch of the heat transfer and pressure loss characteristic of two tube types in the bundle. By means of suitable parameters for heat flow and pressure loss a comparison will be made of the heat transfer and pressure loss power of the axial-flow furried-tube bundle systems investigated here and conventional heat exchangers. (orig.)

  12. Effect of the Moments of Probability Density Function for Non-uniform Air Flow Distribution on the Hydraulic Performance of a Fin-tube Heat Exchanger

    OpenAIRE

    Wai Meng Chin; Vijay R. Raghavan

    2011-01-01

    The work presented in this paper examines the effect of a non-uniform airflow velocity distribution on the air pressure drop through the fin passages of a single row fin-tube heat exchanger. Water flow rate through the tubes and its temperature are taken as constant. Maldistribution of the airflow increases the average pressure drop with respect to that of a uniform flow. As a result of this, the pumping power required by the fan or blower will also increase. The increase of the pumping power...

  13. Numerical Analysis for Optimal Design of Fin and Tube Type Adsorber

    Science.gov (United States)

    Kariya, Keishi; Kuwahara, Ken; Shigeru, Koyama

    Adsorption cooling systems driven by low temperature waste heat (below 100°C) or renewable energy sources have gained considerable attention as one of the solutions for both energy and environment related problems. In this study, a two dimensional numerical analysis is carried out to evaluate the adsorption characteristics and to determine the performance of a fin and tube type adsorber/desorber heat exchanger; activated carbon fiber (ACF) of type A-20, which has relatively higher surface area, and ethanol are used as adsorbent/refrigerant pair. The effects of heat exchanger design configurations such as fin height, fin thickness, fin pitch, tube diameter and apparent density of ACF bed on the performance are examined numerically. The simulation results show that the cooling capacity can be optimized in the condition of fin height 15mm and fin pitch 5.5mm when other parameters are fixed.

  14. 3D analysis of thermal exchange in finned batteries. A comparison between round and elliptical tubes

    International Nuclear Information System (INIS)

    In this paper a numerical 3D analysis of the thermal exchange in air-cooled finned batteries has been carried out. Speed and temperature values in each hub of the numerical simulation domain have been reckoned both at different air flows and with different shapes of the tubes. The thermal power exchanged between tubes and air is obtained by the simulation of a numerical model of a finned battery with round section tubes and is compared to the values obtained for three batteries with elliptical section tubes. The comparison has been performed for different values of the air input speed

  15. Experimental Research on heat transfer enhancement of lubricating-oil cooler with mixing integral pin-fin tubes and plain tubes

    International Nuclear Information System (INIS)

    A lot of comparison experimental research has been done to the lubricating-oil cooler with mixing integral pin-fin tubes and plain tubes. It is discovered that the mixing integral pin-fin tubes heat transfer capacity in unit volume is higher, pressure drop is lower, and the very strong heat transfer ability than plain tubes when oil volume flow rate is at constant value. The results show the performance of lubricating-oil cooler with mixing integral pin-fin tubes and plain tubes is superiority. So this can made lubricating-oil cooler miniaturize in the same Heat changing condition. (authors)

  16. CFD analysis of tube-fin 'no-frost' evaporators

    Directory of Open Access Journals (Sweden)

    Jader R Barbosa, Jr

    2010-12-01

    Full Text Available The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD. The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configuration. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The average errors of the heat transfer rate, thermal conductance and pressure drop were 10%, 3% and 11%, respectively. The CFD model was then used to assess the influence of geometric parameters such as the presence and position of the electrical heater coil relative to the tubes, the fin configuration and the width of the by-pass clearance between the outer edge of the fins and the tube bank for conditions typical of the design of household refrigeration appliances

  17. CFD analysis of tube-fin 'no-frost' evaporators

    Scientific Electronic Library Online (English)

    Jader R, Barbosa, Jr; Christian J. L, Hermes; Cláudio, Melo.

    2010-12-01

    Full Text Available The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD). The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configurat [...] ion. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The average errors of the heat transfer rate, thermal conductance and pressure drop were 10%, 3% and 11%, respectively. The CFD model was then used to assess the influence of geometric parameters such as the presence and position of the electrical heater coil relative to the tubes, the fin configuration and the width of the by-pass clearance between the outer edge of the fins and the tube bank for conditions typical of the design of household refrigeration appliances

  18. Numerical Analysis on Optimization of a Fin and Tube Type Adsorber/Desorber Heat Exchanger using ACF/C2H5OH Pair

    Science.gov (United States)

    Kariya, Keishi; Kuwahara, Ken; Koyama, Shigeru

    This study deals with a two dimensional numerical analysis of the fin and tube type adsorber/desorber heat exchanger design such as fin height, fin pitch, fin thickness and tube diameter effect on the performance of closed adsorption cooling system with activated carbon fiber (ACF) of type A-20, which has relatively higher surface area, and ethanol pair. The simulation results show that the fin tube diameter is effective on the performance of the heat exchanger. It is also found that the cycle COP can be optimized in the condition of fin pitch 4.5mm and fin height 20mm, respectively when other parameters are fixed.

  19. Experimental investigation of water sprayed finned heat exchanger tube bundles

    International Nuclear Information System (INIS)

    Experimental investigations have been made to study the performance of two finned tube-bundle heat exchangers (FORGO type) when wetted by water sprays. The heat exchangers are designed to cool water in a dry cooling tower. The test-elements had a frontal area of 1 m2. The water sprays were created by 20 nozzles, 200 mm in front of the heat exchangers. Air velocities at the inlet of the coolers were in the range 0,8 m/s to 12 m/s and initial temperature differences ITD reached 45 degrees C. The test facility was designed to determine the combined latent and sensible heat fluxes in the wetted heat exchanger, the airside pressure drop and the air humidity and temperature at the exchanger inlet and outlet, and to measure the weight of the water wetting the cooler's surface. The sprayed test elements were investigated in different positions, but most of the experiments were carried out in the position with the fins horizontal

  20. CFD analysis of tube-fin 'no-frost' evaporators

    OpenAIRE

    Jader R. Barbosa, Jr.; Christian J. L Hermes; Cláudio Melo

    2010-01-01

    The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD). The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configuration. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The...

  1. Performance of synchronized fins in biomimetic propulsion.

    Science.gov (United States)

    Shoele, Kourosh; Zhu, Qiang

    2015-04-01

    By using a two-dimensional model of ray fins, we numerically investigate the thrust generation by closely-coupled fins with an immersed boundary approach. The concentration is on the performance enhancement through fin-fin interactions and the underlying vortex control mechanisms in three representative systems, a two-fin tandem configuration, a two-fin parallel configuration, and a three-fin triangular configuration. In all these systems the thrust generation can be significantly increased in comparison with single fins. Unlike previous studies of tandem fins, in which the gap and phase lag between the two fins were considered separately, our study shows that the dynamics of the system is determined by a parameter that combines these two (the global phase difference). The optimal performance occurs as this parameter is around ? (destructive mode), and the worst performance occurs when it is around 0 (constructive mode). Interestingly, contrary to the vorticity cancellation scenario implied by its name, our simulations show that in the destructive mode there is in fact a wake re-organization mechanism, during which vortices with the same rotational direction shed from the two fins are attracted towards each other and merge. Subsequently, the wake downstream becomes a strong and well-organized reverse Kármán vortex street, which explains the increased thrust. In the parallel system, the best performance occurs in cases when the two fins are in opposites phases. Both the thrust and efficiency increase as the gap between the fins decreases, until a symmetry-breaking instability occurs in the wake and the efficiency starts plunging due to the increase in lateral force generation. In the triangular formation, the highest thrust generation also occurs in the destructive mode. However, no further increase in performance is observed compared with the tandem system. PMID:25821945

  2. Fouling of HVAC fin and tube heat exchangers

    International Nuclear Information System (INIS)

    Fin and tube heat exchangers are used widely in residential, commercial and industrial HVAC applications. Invariably, indoor and outdoor air contaminants foul these heat exchangers. This fouling can cause decreased capacity and efficiency of the HVAC equipment as well as indoor air quality problems related to microbiological growth. This paper describes laboratory studies to investigate the mechanisms that cause fouling. The laboratory experiments involve subjecting a 4.7 fins/cm (12 fins/inch) fin and tube heat exchanger to an air stream that contains monodisperse particles. Air velocities ranging from 1.5-5.2 m/s (295 ft/min-1024 ft/min) and particle sizes from 1-8.6(micro)m are used. The measured fraction of particles that deposit as well as information about the location of the deposited material indicate that particles greater than about 1(micro)m contribute to fouling. These experimental results are used to validate a scaling analysis that describes the relative importance of several deposition mechanisms including impaction, Brownian diffusion, turbophoresis, thermophoresis, diffusiophoresis, and gravitational settling. The analysis is extended to apply to different fin spacings and particle sizes typical of those found in indoor air

  3. Experimental Investigation of Heat Transfer and Pressure Drop Characteristics of H-type Finned Tube Banks

    OpenAIRE

    Heng Chen; Yungang Wang; Qinxin Zhao; Haidong Ma; Yuxin Li; Zhongya Chen

    2014-01-01

    H-type finned tube heat exchanger elements maintain a high capacity for heat transfer, possess superior self-cleaning properties and retain the ability to effect flue gas waste heat recovery in boiler renovations. In this paper, the heat transfer and pressure drop characteristics of H-type finned tube banks are studied via an experimental open high-temperature wind tunnel system. The effects of fin width, fin height, fin pitch and air velocity on fin efficiency, convective heat transfer coe...

  4. Heat transfer coefficients and pressure drops for R-134a and an ester lubricant mixture in a smooth tube and a micro-fin tube

    Energy Technology Data Exchange (ETDEWEB)

    Eckels, S.J. [Kansas State Univ., Manhattan, KS (United States); Doerr, T.M.; Pate, M.B. [Iowa State Univ., Ames, IA (United States). Mechanical Engineering Dept.

    1998-10-01

    This paper reports average heat transfer coefficients and pressure drops during the evaporation and condensation of mixtures of R-134a and a 150 SUS penta erythritol ester branched-acid lubricant. The smooth tube and micro-fin tube tested in this study had outer diameters of 9.52 mm (3/8 in.). The micro-fin tube had 60 fins, a fin height of 0.2 mm (0.008 in), and a spiral angle of 18{degree}. The objective of this study is to evaluate the effectiveness of the micro-fin tube with R-134a and to determine the effect of circulating lubricant. The experimental results show that the micro-fin tube has distinct performance advantages over the smooth tube. For example, the average heat transfer coefficients during evaporation and condensation in the micro-fin tube were 50--200% higher than those for the smooth tube, while the average pressure drops were on average only 10--50% higher. The experimental results indicate that the presence of a lubricant degrades the average heat transfer coefficients during both evaporation and condensation at high lubricant concentrations. Pressure drops during evaporation increased with the addition of a lubricant in both tubes. For condensation, pressure drops were unaffected by the addition of a lubricant.

  5. Compensation of airflow maldistribution in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Tiedemann, Thomas

    2012-01-01

    Compensation of airflow maldistribution in fin-and tube evaporators for residential air-conditioning is investigated with regards to circuitry design and control of individual channel superheats. In particularly, the interlaced and the face split circuitry designs are compared numerically using a linear velocity profile and a CFD predicted velocity profile obtained from Kærn (2011d) in dry and wet conditions. The circuitry models are validated experimentally in wet conditions, and for this purpose a test case interlaced evaporator (17.58 kW) was reconstructed in order to become a face split evaporator by modifying its U-bend connections. Furthermore, a 14% and 28% blockage of the face split evaporator is studied experimentally with control of individual channel superheats. It is shown that the face split circuitry with compensation gives the best performance in both dry and wet conditions, however with lower gains in wet conditions (around 3% in cooling capacity and 7-9% in UA-value). This performance gain incooling capacity is below the uncertainty in standard experiments, however the gain may be revealed and/or validated by the possible area savings experimentally, i.e. in terms of overall UA-value.

  6. Quantitative experiments on thermal hydraulic characteristics of an annular tube with twisted fins

    International Nuclear Information System (INIS)

    Thermal hydraulic experiments measuring critical heat flux (CHF) and pressure drop of an annular tube with twisted fins, ''annular swirl tube'', has been performed to examine its applicability to the ITER divertor cooling structure. The annular swirl tube consists of two concentric circular tubes, the outer and inner tubes. The outer tube with outer and inner diameters (OD and ID) of 21 mm and 15 mm is made of Cu-alloy that is CuCrZr and oe of candidate materials of the ITER divertor cooling tube. The inner tube with OD of 11 mm and ID of 9 mm is made of stainless steal. It has an external swirl fin with twist ratio (y) of three to enhance its heat transfer performance. In this tube, cooling water flows inside of the inner tube first, and then returns into an annulus between the outer and inner tubes with a swirl flow at an end-return of the cooling tube. The CHF experiments show that no degradation of CHF of the annular swirl tube in comparison with the conventional swirl tube whose dimensions are similar to those of the outer tube of the annular swirl tube. A minimum axial velocity of 7.1 m/s is required to remove the incident heat flux of 28MW/m2, the ITER design value. Applicability of the JAERI's correlation for the heat transfer to the annular swirl tube is also demonstrated by comparing the experimental results with those of the numerical analysis. The friction factor correlation for the annular flow with the twisted fins is also proposed for the hydrodynamic design of the ITER vertical target. The least pressure drop at the end-return is obtained by using the hemispherical end-plug. Its radius is the same as that of ID of the outer cooling tube. These results show that thermal-hydraulic performance of the annular swirl tube is promising in application to the cooling structure for the ITER vertical target. (author)

  7. Compensation of flow maldistribution in fin-and-tube evaporators for residential air-conditioning

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Brix, Wiebke

    2011-01-01

    Compensation of flow maldistribution in multi-channel fin-and-tube evaporators for residential air-conditioning is investigated by numerical modeling. The considered sources of maldistribution are distribution of the liquid and vapor phases in the distributor and non-uniform airflow distribution. Fin-and-tube heat exchangers usually have a predefined circuitry, however, the evaporator model is simplified to have straight tubes, in order to perform a generic investigation. The compensation of flow maldistribution is performed by control of the superheat in the individual channels. Furthermore, the effect of combinations of individual maldistribution sources is investigated for different evaporator sizes and outdoor temperatures. It is shown that a decrease in cooling capacity and coefficient of performance by flow maldistribution can be compensated by the control of individual channel superheat. Alternatively, a larger evaporator may be used.

  8. Analysis of internal helically finned tubes for parabolic trough design by CFD tools

    International Nuclear Information System (INIS)

    Highlights: ? Parabolic trough collectors life improvement by internally finned tubes. ? Solar thermal oil degradation reduction by homogenization of temperature profile in parabolic trough collectors. ? Efficiency enhancement of parabolic trough collectors by finned tubes. ? CFD analysis of finned parabolic trough collector tubes. -- Abstract: This paper has analysed the effect of the utilization of internal finned tubes for the design of parabolic trough collectors with computational fluid dynamics tools. Our numerical approach has been qualified with the computational estimation of reported experimental data regarding phenomena involved in finned tube applications and solar irradiation of parabolic trough collector. The application of finned tubes to the design of parabolic trough collectors must take into account features as the pressure losses, thermal losses and thermo-mechanical stress and thermal fatigue. Our analysis shows an improvement potential in parabolic trough solar plants efficiency by the application of internal finned tubes.

  9. Condensation heat transfer in horizontal elliptical tubes with internal fins

    International Nuclear Information System (INIS)

    In this paper condensation heat transfer inside horizontal elliptical tubes is investigated for a stratified, concurrent two-phase flow of vapor and liquid. The analysis takes into account the effects of interfacial shear, axial pressure gradient, saturation temperature level and the development of the stratified angle associated with the accumulated condensate layer at the bottom of the tube. The governing equations are solved numerically with finite difference method. The results are presented for two cases; i.e. with and without fins. Also different values of ellipticity (b/a) are considered and discussed. At first, the results for special case of circle (b/a=1) are compared with available data in the literature that shows good agreement. Also, comparing of obtained results for different values of ellipticity shows that for ellipticity values of less than one, condensation heat transfer is greater than circular tubes; both above cases show greater transfer than those corresponding to ellipticity values bigger than one

  10. Infrared thermography investigation of local heat transfer in a plate fin and two-tube rows assembly

    International Nuclear Information System (INIS)

    An experimental study is performed using an infrared thermography system. The experimental method uses the temperature transient variation of a thin plate (tested fin) in order to obtain detailed quantitative heat transfer coefficients. The method developed is similar to the lumped capacitance method usually used to measure heat transfer coefficient on heat exchanger fin models. But the method presented here exploits the capabilities of infrared thermography to measure surface temperatures in a transient technique in order to take into account errors effects due to tangential conduction and radiation of the tested fin. The method is validated using a two-dimensional channel experiment and its advantages are highlighted using a plate fin and two-tube rows assembly experiment. Moreover, convection coefficient variations with fin pitch and frontal air velocity of an automotive plate fin and two-tube rows assembly are also examined

  11. Heat transfer analysis of flat and louvered fin-and-tube heat exchangers using CFD

    OpenAIRE

    Carija, Z.; Frankovic, B.

    2008-01-01

    This paper analyzes the fluid flow and heat exchange on the air side of a multi-row fin-and-tube heat exchanger. A comparison is given between fin-and-tube heat exchanger characteristics with flat and louvered fins in a wider range of operating conditions defined by Reynolds number (based on fin spacing and air frontal velocities). The detailed representation of calculated data for the louvered heat exchanger shows significantly better heat transfer characteristics and a ...

  12. Numerical Analysis on Adsorption Characteristics of Activated Carbon/Ethanol Pair in Finned Tube Type Adsorber

    Science.gov (United States)

    Makimoto, Naoya; Kariya, Keishi; Koyama, Shigeru

    The cycle performance of adsorption cooling system depends on the thermophysical properties of the adsorbent/refrigerant pair and configuration of the adsorber/desorber heat exchanger. In this study, a twodimensional analysis is carried out in order to clarify the performance of the finned tube type adsorber/desorber heat exchanger using a highly porous activated carbon powder (ACP)/ethanol pair. The simulation results show that the average cooling capacity per unit volume of adsorber/desorber heat exchanger and coefficient of performance (COP) can be improved by optimizing fin thickness, fin height, fin pitch and tube diameter. The performance of a single stage adsorption cooling system using ACP/ethanol pair is also compared with that of activated carbon fiber (ACF)/ethanol pair. It is found that the cooling capacities of each adsorbent/refrigerant pair increase with the decrease of adsorption/desorption time and the cooling capacity of ACP/ethanol pair is approximately 2.5 times as much as that of ACF/ethanol pair. It is also shown that COP of ACP/ethanol pair is superior to that of ACF/ethanol pair.

  13. Experimental Investigation of Heat Transfer and Pressure Drop Characteristics of H-type Finned Tube Banks

    Directory of Open Access Journals (Sweden)

    Heng Chen

    2014-11-01

    Full Text Available H-type finned tube heat exchanger elements maintain a high capacity for heat transfer, possess superior self-cleaning properties and retain the ability to effect flue gas waste heat recovery in boiler renovations. In this paper, the heat transfer and pressure drop characteristics of H-type finned tube banks are studied via an experimental open high-temperature wind tunnel system. The effects of fin width, fin height, fin pitch and air velocity on fin efficiency, convective heat transfer coefficient, integrated heat transfer capacity and pressure drop are examined. The results indicate that as air velocity, fin height and fin width increase, fin efficiency decreases. Convective heat transfer coefficient is proportional to fin pitch, but inversely proportional to fin height and fin width. Integrated heat transfer capacity is related to fin efficiency, convective heat transfer coefficient and finned ratio. Pressure drop increases with the increase of fin height and fin width. Finally, predictive correlations of fin efficiency, Nusselt number and Euler Number are developed based on the experimental data.

  14. Improvement of the gas-oil heat exchangers based on the bimetallic finned tubes

    OpenAIRE

    Borisov, N. A.

    2014-01-01

    The heat exchanger is essential for the process of heat transfer in the industrial equipment. It is widely used in all areas of industry, especially in technology, metallurgy, power, transportation, aviation, aerospace and other sectors. In recent years, with the development of new technologies and energy, the necessity of improving the heat exchanger performance is drawing more and more attention of industry. Devices with finned tubes are one of the most common types of extended surface heat...

  15. Development and production of tubes with inner finning for nuclear power

    International Nuclear Information System (INIS)

    Increased heat transfer due to inner finning of tubes results in increasing the life of tubes in steam generators of sodium cooled reactors and in limiting unfavourable effects of temperature changes on the tubes. The development was therefore commenced of tubes with inner longitudinal and inner helical fins. The technology of drawing tubes on linear drawing benches using a short cylindrical mandrel was accepted as most suitable. The effect was studied of the geometry of tools and fixtures and the relationships were tested between the size of drawing reduction of the diameter and the initial wall thickness of different tubes. It was found that the increase in the fin height depended on the size of the wall thickness reduction. Tubes 18 mm in diameter, 3 mm in wall thickness and 0.5 and 1 mm in fin height, 2 mm in fin width and 5.5 to 7 m in length, and tubes with helical fins of 0.5 mm and 1 mm in fin height and with a pitch of 200, 250 and 300 mm were subject to tests confirming that for longitudinal fins heat transfer improved by 20% and for helical fins by 50%. (Z.M.)

  16. Heat transfer analysis of a finned-tube evaporator for engine exhaust heat recovery

    International Nuclear Information System (INIS)

    Highlights: ? The characteristic of the exhaust waste heat for a light duty diesel engine is analyzed. ? A mathematical model is established for a finned-tube evaporator used in an ORC. ? The heat transfer performance of the finned-tube evaporator is evaluated throughout the engine’s operating region. - Abstract: The organic Rankine cycle (ORC) can be used to recover waste heat from an internal combustion engine. In such a system, the evaporator design is critical. Determining the amount of heat that can be transferred in a designed evaporator is extremely important for a successful ORC system. In this paper, the performance of a finned-tube evaporator used to recover exhaust waste heat from a diesel engine is presented. First, the exhaust heat of the chosen diesel engine is evaluated based on the measured data. Subsequently, a mathematical model of the evaporator is created based on the detailed geometry and the specific ORC working conditions. Then, the heat transfer of the evaporator is estimated as the diesel engine runs through all of its operating regions defined by the engine speed and the engine load. The results show that the exhaust temperature at the evaporator outlet increases with engine speed and engine load. Although the convective heat transfer coefficient of the organic working fluid is significantly larger than that of the exhaust gas, the overall heat transfer coefficient is slightly greater than that of the exhaust gas. Furthermore, the hea exhaust gas. Furthermore, the heat transfer rate is the greatest in the preheated zone and least in the superheated zone. Consequently, the heat transfer area for the preheated zone is nearly half of the total area. In addition, the area of the superheated zone is slightly greater than that of the two-phase zone. It is concluded that the heat transfer area for a finned tube evaporator should be selected carefully based on the engine’s most typical operating region.

  17. Quantitative infrared investigation of local heat transfer in a circular finned tube heat exchanger assembly

    International Nuclear Information System (INIS)

    Highlights: • Infrared thermography and transient technique are used to estimate local heat transfer. • Calculation model is integrated between local time bounds chosen with an original criterion. • Thermal horseshoe vortices imprints are analyzed by following their angular evolution. -- Abstract: This work deals with the local heat transfer coefficient evaluation over the fin of the second row of a staggered circular finned tube heat exchanger assembly. The coefficient distribution is determined by using a transient technique and by calculating the energy balance during the fin cooling. The calculation model takes into account radiation with the surrounding and lateral heat conduction into the material. The method uses infrared measurements and integration between time bounds that depend on space. It is proposed to choose the integration bounds with an original criterion based on local heat transfer. Validation is performed on the reference case consisting in a thin plate in an aerodynamically and thermally developing channel flow. Then, distributions of Nusselt number on the circular fin are presented for several Reynolds numbers. The high resolution of the whole method and set-up allow detecting thermal imprints of developing horseshoe vortices. These imprints are analyzed by following their angular evolution around the tube

  18. Air-side heat transfer characteristics of spiral-type circular fin-tube heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Mooyeon; Kang, Taehyung; Kim, Yongchan [Department of Mechanical Engineering, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713 (Korea)

    2010-03-15

    The objective of this study is to investigate the air-side heat transfer characteristics of spiral-type circular fin-tube heat exchangers used as evaporators in household refrigerators. The j-factors of the tested heat exchangers under non-frosting conditions were measured by varying the fin pitch, number of tube rows, and fin alignment. The j-factors of the spiral-type circular fin-tube heat exchangers were analyzed as a function of heat exchanger geometries and then compared with those of the flat plate fin-tube heat exchangers with discrete fins. Two empirical correlations of the j-factors were developed separately for the inline and the staggered fin alignment as a function of the Reynolds number, number of tube rows, and dimensionless fin pitch normalized by the hydraulic diameter. The mean deviation of the predictions using the present correlations from the measured data was 4.78% for the inline fin alignment and 6.02% for the staggered fin alignment. (author)

  19. Steam generator tube performance

    International Nuclear Information System (INIS)

    A review of the performance of steam generator tubes in 116 water-cooled nuclear power reactors showed that tubes were plugged at 54 (46 percent) of the reactors. The number of tubes removed from service decreased from 4 692 (0.30 percent) in 1981 to 3 222 (0.20 percent) in 1982. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that have used only volatile treatment, with or without condensate demineralization

  20. Steam generator tube performance

    International Nuclear Information System (INIS)

    A review of the performance of steam generator tubes in 110 water-cooled nuclear power reactors showed that tubes were plugged at 46 (42 percent) of the reactors. The number of tubes removed from service increased from 1900 (0.14 percent) in 1980 to 4692 (0.30 percent) in 1981. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that used all-volatile treatment since start-up. At one reactor a large number of degraded tubes were repaired by sleeving which is expected to become an important method of tube repair in the future

  1. Pulse tube refrigerator performance

    International Nuclear Information System (INIS)

    The performance of pulse tube coolers is being studied in order to determine their suitability for development into long-life space coolers. Coolers based on the pulse tube phenomenon appear to be attractive for long-life space application because of their inherent simplicity. Single-stage and two-stage pulse tube test coolers have been designed and tested. In these early tests a single stage cooler has achieved a low temperature of 53 K while rejecting heat above 300 K. An unoptimized two-stage cooler has reached 26 K while rejecting heat above 300 K. Performance measurements for the coolers is presented. 15 refs

  2. Accuracy of one-dimensional design procedures for finned-tube heat exchangers

    OpenAIRE

    Comini, G.; Savino, S.

    2009-01-01

    Abstract In design procedures for finned-tube heat exchangers a common simplification is assuming that the temperature distribution is one-dimensional. In this way, the heat exchanger can be schematized as a thermal circuit with three thermal resistances in series: internal convection to the tube, conduction through the tube wall, and external convection through the fin assembly. The aim of this work is to quantitatively evaluate the accuracy of one-dimensional schematizations in t...

  3. Carbon-foam finned tubes in air-water heat exchangers

    International Nuclear Information System (INIS)

    An engineering model is formulated to account for the effects of porosity and pore diameter on the hydrodynamic and thermal performance of a carbon-foam finned tube heat exchanger. The hydrodynamic and thermal resistances are obtained from well-established correlations that are extended herein to account for the influence of the porous carbon foam. The influence of the foam is characterized on the basis of a unit-cube geometric model that describes the internal structure, the exposed surface, the permeability and the effective conductivity as a function of porosity and pore diameter. The engineering model is validated by comparison with experiments that characterize heat transfer in an air-water radiator made from porous carbon foam. The model is also used in to conduct a parametric study to show the influence of the porosity and pore diameter of the foam. The parametric study suggests that in comparison to conventional aluminum finned-tube radiators, improvements of approximately 15% in thermal performance are possible without changing the frontal area, or the air flow rate and pressure drop. The engineering model developed herein can be used by engineers to assess quantitatively the suitability of porous carbon foam as a fin material in the design of air-water heat exchangers

  4. Laminar fluid flow and heat transfer in a fin-tube heat exchanger with vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Yanagihara, J.I.; Rodriques, R. Jr. [Polytechnic School of Univ. of Sao Paolo, Sao Paolo (Brazil). Dept. of Mechanical Engineering

    1996-12-31

    Development of heat transfer enhancement techniques for fin-tube heat exchangers has great importance in industry. In recent years, heat transfer augmentation by vortex generators has been considered for use in plate fin-tube heat exchangers. The present work describes a numerical investigation about the influence of delta winglet pairs of vortex generators on the flow structure and heat transfer of a plate fin-tube channel. The Navier-Stokes and Energy equations are solved by the finite volume method using a boundary-fitted coordinate system. The influence of vortex generators parameters such as position, angle of attack and aspect ratio were investigated. Local and global influences of vortex generators in heat transfer and flow losses were analyzed by comparison with a model using smooth fin. The results indicate great advantages of this type of geometry for application in plate fin-tube heat exchangers, in terms of large heat transfer enhancement and small pressure loss penalty. (author)

  5. Burnout in the boiling of water and freon-113 on tubes with annular fins

    International Nuclear Information System (INIS)

    This paper presents the results of numerical calculations of burnout heat flux associated with the boiling of Freon-113 and water on an annular fin of constant thickness which have been approximated by simple analytical relations. These are used to calculate the critical burnout parameters of tubes with an annular fin assembly. The calculated data may be used for the analysis of tubes with an annular fin assembly over a wide range of variation of the thermophysical properties of the material and geometrical parameters of the fin assembly

  6. Analysis of refrigerant mal-distribution : in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    Refrigerant mal-distribution in fin-and-tube evaporators for residential air-conditioning is investigated numerically in this paper. Essentially the influence of refrigerant mal-distribution on capacity of an evaporator is reported. In order to investigate, a model of a fin-and-tube evaporator is developed in the object-oriented modeling language Modelica. The evaporator model is a dynamic distributed one-dimensional homogeneous model, but will be used here to present results in steady state. Fin-and-tube evaporators usually have a complex circuitry, however the evaporator will be simplified to be two straight tubes. The refrigerant maldistribution is then induced to the evaporator by varying the vapor quality at the inlet to each tube and the air-flow across each tube. Finally it is shown that mal-distribution can be compensated by an intelligent distributor, that ensures equal superheat temperature in both tubes. The refrigerant is R410a.

  7. High temperature design of finned-tube sodium-to-air heat exchanger in a sodium test loop

    International Nuclear Information System (INIS)

    Highlights: • High temperature design of finned-tube heat exchanger (FHX) in SFR were conducted. • Full 3D FE analyses for the sodium-to-air heat exchanger unit were performed. • Stress levels of the FHX unit based on full 3D analyses were not severe. • Creep–fatigue damage as per design rules was evaluated to be within allowable limit. - Abstract: A sodium test loop called ‘SELFA’ (sodium thermal-hydraulic experiment loop for finned-tube sodium-to-air heat exchanger) for simulating thermal hydraulic behavior of the FHX (finned-tube sodium-to-air heat exchanger) unit in a Korean prototype sodium-cooled fast reactor is planned to be constructed at KAERI (Korea Atomic Energy Research Institute). In this study, the elevated temperature design for a model FHX and creep–fatigue damage evaluation have been conducted for the model according to the design codes of ASME section III subsection NH and RCC-MRx based on full 3D finite element analyses. Design optimization for the finned-tubes and tube arrangements in the scaled-down FHX has been performed. The materials of the FHX and piping systems are austenitic stainless steel type 316. The design temperature of the SELFA test loop is 600 °C and the design pressure is 1 MPa. The damage evaluation results have shown that no creep–fatigue damage occurs in the present design of the FHX under the intended test conditions

  8. Studi Analitik dan Numerik Perpindahan Panas pada Fin Trapesium (Studi Kasus pada Finned Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Ahmad Zaini

    2013-09-01

    Full Text Available Penambahan fin pada pipa penukar kalor merupakan suatu upaya memperbesar perpindahan kalor konduksi dan konveksi, dengan cara memperluas bidang geometri. Pada penelitian ini dianalisa secara analitik dan numerik perpindahan kalor pada fin dengan profil longitudinal tidak seragam atau berubah terhadap jarak dari dasar fin, dengan memvariasikan ketebalan ujung fin. Hasil dari kedua studi ini tidak jauh berbeda, pada keduanya menjelaskan bahwa fin dengan ketebalan ujung 0,9 mm (fin trapesium terbalik paling baik dari 5 variasi lainnya; serta perubahan temperatur paling besar terjadi pada sepertiga pertama dari panjang  fin, ini artinya pelepasan kalor terbesar terjadi pada daerah tersebut. Perbedaannya adalah pada persentase penurunan temperatur sepanjang  fin terhadap temperatur dasar fin, untuk ketebalan 0,9 mm pada studi analitik sebesar 91,92% dan pada studi numerik sebesar 91,78%. Hal ini berarti metode penyelesaian persamaan diferensial orde 2 dengan koefisien variabel dengan cara pembedahan koefisien variabel pada ODE, sudah benar dan valid. Namun bila ditinjau dari waktu yang diperlukan untuk komputasinya, studi analitik membutuhkan waktu lebih lama. Waktu yang diperlukan dalam komputasinya tergantung dari fungsi koefisien variabel.

  9. Steam generator tube performance

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1980. Tube defects occurred at 38% of the 97 reactors surveyed. This is a marginal improvement over 1979 when defects occurred at 41% of the reactors. The number of failed tubes was also lower, 0.14% of the tubes in service in 1980 compared with 0.20% of those in service in 1979. Analysis of the causes of these failures indicates that stress corrosion cracking was the leading failure mechanism. Reactors that used all-volatile treatment of secondary water, with or without full-flow condensate demineralization since start-up showed the lowest incidence of corrosion-related defects

  10. Design of Plate-Fin Tube Dehumidifiers for Humidification-Dehumidification Desalination Systems

    OpenAIRE

    Sievers, Martin; Lienhard, John H.

    2014-01-01

    A two-dimensional numerical model of a plate-fin tube heat exchanger for use as a dehumidifier in a humidification-dehumidification (HDH) desalination systems is developed, because typical heating, ventilating, and air conditioning (HVAC) dehumidifier models and plate-fin tube dehumidifier geometries are not intended for the considerably higher temperature and humidity ratio differences which drive heat and mass transfer in HDH desalination applications. The experimentally validated model is ...

  11. Experimental analysis of ammonia condensation on smooth and integral-fin titanium tubes

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Uhia, Francisco J.; Diz, Ruben [Area de Maquinas y Motores Termicos, E.T.S. de Ingenieros Industriales, University of Vigo, Campus Lagoas-Marcosende No 9, 36310 Vigo (Spain)

    2009-09-15

    This paper reports on the experimental research conducted to study the condensation of ammonia on smooth and integral-fin (32 fpi) titanium tubes of 19.05 mm outer diameter. Experiments were carried out at saturation temperatures of 30, 35, 40 and 45 C and wall subcoolings from 1 to 8 C. The results show that the condensation coefficients on the smooth tubes are well predicted by the Nusselt theory with an average error of +0.66% and within a deviation between -6.6% and +8.3%. The enhancement factors provided by the integral-fin tubes range from 0.77 to 1.22. The low enhancement factors are due to the high condensate retention between fins, which brings about flooded fractions of the tube perimeter from 62.9% to 73.2%, and the low thermal conductivity of titanium. The Briggs and Rose [1994. Effect of fin efficiency on a model for condensation heat transfer on a horizontal, integral-fin tube. Int. J. Heat Mass Transfer 37, 457-463.] model, which accounts for the conduction in the fins, predicts the experimental data with a mean overestimation of 20%. The analysis of the partial thermal resistances in the overall heat transfer process points out the convenience of enhancing the outside ammonia condensation when high water velocities are considered inside the tubes. (author)

  12. Effective Heat Transfer Enhancement in Finned Tube Heat Exchanger with Different Fin Profiles

    OpenAIRE

    J.A.Livingston; Selvakumar, P

    2013-01-01

    During cross flow in a heat exchanger, heat transfer in the front portion of the tube is more compared to back portion of the tube. This is due to less formation of vortices at the backside of the tube. For uniform heat transfer to take place throughout the tube, it is necessary to increase the vortex formation at the rear side of the tube. The aim of this study is to explore the possibilities of improving the flow structure and thereby increasing uniform heat transfer around the tubes by int...

  13. Experimental Study on Frost Height of Round Plate Fin-Tube Heat Exchangers for Mobile Heat Pumps

    Directory of Open Access Journals (Sweden)

    Dong-Yeon Lee

    2012-09-01

    Full Text Available The objective of this study was to provide experimental data that could be used to predict frost growth and frost performance of a round plate fin-tube heat exchanger for low temperature heat pumps used in zero emission vehicles under cold weather conditions. In this study, round plate fin-tube heat exchangers were tested with variation of the fin space, air flow rate, relative humidity, and inlet air temperature. Frost height was measured and considered with the boundary layer interruption between fins. Frost height for 8.0 mm of fin space was increased by approximately 91.9% with an increase of relative humidity from 50.0% to 80.0%. The growth rate of frost height at 1.2 m3/min was observed to be 13.0% greater than that at 0.8 m3/min. Finally, the variation of the blockage ratio with fin space would be an important reference for designing advanced heat exchangers that operate under cold weather conditions.

  14. Effective Heat Transfer Enhancement in Finned Tube Heat Exchanger with Different Fin Profiles

    OpenAIRE

    Livingston, J. A.; Selvakumar, P.

    2013-01-01

    During cross flow in a heat exchanger, heat transfer in the front portion of the tube is more compared to back portion of the tube. This is due to less formation of vortices at the backside of the tube. For uniform heat transfer to take place throughout the tube, it is necessary to increase the vortex formation at the rear side of the tube. The aim of this study is to explore the possibilities of improving the flow structure and thereby increasing uniform heat transfer...

  15. Numerical Investigation of Air-Side Heat Transfer and Pressure Drop in Circular Finned-Tube Heat Exchangers

    OpenAIRE

    Mon, Mi Sandar

    2009-01-01

    A three-dimensional numerical study is performed to investigate the heat transfer and pressure drop performance on the air-side of circular finned tube bundles in cross flow. New heat transfer and pressure drop correlations for the air-cooled heat exchangers have been developed with the Reynolds number ranging from 5000 to 70000. The heat transfer and pressure drop results agree well with several existing experimental correlations. In addition, the influence of the geometric parameters on the...

  16. Performance Analysis of FinFET Device at 60nm

    Directory of Open Access Journals (Sweden)

    I.Flavia Princess Nesamani#1 , Rijo.P.C

    2013-03-01

    Full Text Available A Double Gate (DG FinFET device with High K dielectric in 60nm is presented which provides high performance compared to normal MOSFET device in terms of reduction of leakage current. A less leakage current is reported with High-K FinFET device when HfO2 used as High-k material with a dielectric constant of 25. Sentaurus TCAD tool is used to find the performance of the FinFET device

  17. Dry/wet performance of a plate-fin air-cooled heat exchanger with continuous corrugated fins

    International Nuclear Information System (INIS)

    The performance and operating characteristics of a plate-fin heat exchanger in dry/wet or deluge operations was experimentally determined. Development of the deluge heat/mass transfer model continued. The experiments were conducted in a specially-designed wind tunnel at the PNL. Air that was first heated and humidified to specified conditions was circulated at a controlled rate through a 2 ft x 6 ft heat exchanger module. The heat exchanger used in the tests was a wavy surface, plate fin on tube configuration. Hot water was circulated through the tubes at high flow rates to maintain an essentially isothermal condition on the tube side. Deionized water sprayed on the top of the vertically oriented plate fins was collected at the bottom of the core and recirculated. Instrumentation was provided for measurement of flow rates and thermodynamic conditions in the air, in the core circulation water, and in the deluge water. Measurements of the air side pressure drop and heat rejection rate were made as a function of air flow rate, air inlet temperature and humidity, deluge water flow rate, and the core inclination from the vertical. An overall heat transfer coefficient and an effective deluge film convective coefficient was determined. The deluge model, for predicting heat transfer from a wet finned heat exchanger was further developed and refined, and a major extension of the model was formulated that permits simultaneous calculation of both the heat transfer and evaporation rates from the wetted surface. The experiments showed an increase in the heat rejection rate due to wetting, accompanied by a proportional increase in the air side pressure drop. For operation at the same air side pressure drop, the enhancement ratio Q/sub w//Q/sub d/ varied between 2 and 5 for the conditions tested. Thus, the potential enhancement of heat transfer due to wetting can be substantial

  18. Studi Eksperimen Analisa Performa Compact Heat Exchanger Louvered Fin Flat Tube untuk pemanfaatan Waste Energy

    Directory of Open Access Journals (Sweden)

    Taqwim Ismail

    2014-03-01

    Full Text Available Waste Heat Recovery merupakan instalasi yang digunakan untuk memanfaatkan kembali waste energy seperti exhaust gas. Penelitian dilakukan pada compact heat exchanger tipe louvered fin flat tube sebagai salah satu komponen penyusun waste heat recovery system. Eksperimen dilakukan dengan mendesain compact heat exchanger tipe louvered fin flat tube kemudian dilakukan pengujian pada compact heat exchanger yang telah didesain. Pengujian dilakukan dengan memberikan tiga variasi kecepatan putaran fan sisi exhaust gas, yaitu 0.2, 0.3, dan 0.4 m/s untuk mengetahui unjuk kerja yang berbeda dari compact heat exchanger yang telah didesain.  Hasil yang didapatkan dari studi eksperimen ini adalah dimensi dari compact heat exchanger tipe louvered fin flat tube dan beberapa parameter yang menunjukkan unjuk kerja dari compact heat exchanger seperti nilai heat transfer baik dari sisi air maupun sisi exhaust gas, effectiveness, number of transfer unit (NTU, overall heat transfer coefficient, dan  ?TLMTD dari compact heat exchanger.

  19. HEAT TRANSFER AND FLUID FLOW ANALYSIS IN PLATE-FIN AND TUBE HEAT EXCHANGERS WITH DIFFERENT SHAPED VORTEX GENERATORS

    Directory of Open Access Journals (Sweden)

    K.Thirumalai kannan

    2012-03-01

    Full Text Available Numerical analyses were carried out to study the heat transfer and flow in the plate-fin and tube heat exchangers with different shaped vortex generators mounted behind the tubes. The effects of different span angles a (? = 30°, 45° and 60° are investigated in detail for the Reynolds number ranging from 500 to 2500. Numerical simulation was performed by computational fluid dynamics of the heat transfer and fluid flow. The results indicated that the triangle shaped winglet is able to generate longitudinal vortices and improve the heat transfer performance in the wake regions. The case of ? = 45° provides the best heat transfer augmentation than rectangle shape winglet generator in case of inline tubes. Common flow up configuration causes significant separation delay, reduces form drag, and removes the zone of poor heat transfer from the near wake of the tubes.

  20. Comparison of fin-and-tube interlaced and face split evaporators with flow maldistribution and compensation

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2013-01-01

    Flow maldistribution in fin-and tube evaporators for residential air-conditioning is investigated by numerical simulation. In particular, the interlaced and the face split evaporator are compared in flow maldistribution conditions. The considered sources of maldistribution are the liquid/vapor distribution and the airflow distribution. Furthermore, compensation of flow maldistribution by control of individual channel superheat is studied for each evaporator type. It is shown that the interlaced evaporator is better at flow maldistribution than the face split evaporator. However, if individual channel superheats are controlled, the face split evaporator achieves the best performance, i.e. an increase of 7% in overall UA-value and 1.6–2.4% in COP compared to the interlaced evaporator without compensation.

  1. Analysis of flow maldistribution in fin-and-tube evaporators for residential air-conditioning systems

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl

    2011-01-01

    This thesis is concerned with the effects of flow maldistribution in fin-and-tube A-coil evaporators for residential air-conditioning and compensation potentials with regards to system performance. The goal is to create a better understanding of flow maldistribution and the involved physical phenomenons. Moreover, the study investigates the individual and combined effects of non-uniform inlet liquid/vapor distribution, different feeder tube bending and non-uniform airflow. In addition, the possible compensation of these maldistribution sources is investigated by control of individual channel superheat by distributing individual channel mass flow rate continuously (perfect control). The compensation method is compared to the use of a larger evaporator in order to study their trade-off in augmenting system performance (cooling capacity and COP). The studies are performed by numerical modeling in the object-oriented programming language Modelicar and by using the commercial modeling environment Dymola 7.4 (2010). The evaporator model needs to be capable of predicting the flow distribution and circuitry effects, and for these reasons the dynamic distributed one-dimensional mixture two-phase flow model is implemented. The model is verified in steady state with commercial software Coil-Designer (Jiang et al., 2006) and compared to steady state experiments with acceptable results considering the unknown degrees of flow maldistribution for these experiments. Furthermore, the system dynamics in the model were validated and showed that a slip flow model need be used. A test case 8.8 kW residential air-conditioning system with R410A as refrigerant is chosen as baseline for the numerical investigations, and the simulations are performed at standard rating conditions from ANSI/AHRI Standard 210/240 (2008). The investigations are performed on a simplified evaporator tube circuitry (two straight channels), a face split evaporator circuitry and an interlaced evaporator circuitry. The first case is a generic study and serves to provide general results independent of specific type of tube circuitry. The second and third cases are standard tube circuitry designs and these results are thus tube circuitry specific. In addition, a novel method of compensating flow maldistribution is analyzed, i.e. the discontinuous liquid injection principle. The method is based upon the recently developed EcoFlowTM valve by Danfoss A/S, and controls the individual channel superheat by distributing individual mass flow rate discontinuously (on/off injection). The results in this thesis show that flow maldistribution decreases system performance in terms of cooling capacity and COP, but may be compensated significantly by control of individual channel superheat. The generic study (two straight channels) shows that the airflow maldistribution has the largest effect, whereas the liquid/vapor maldistribution has smaller effect and the different feeder tube bending has a minor effect on system performance. The comparison between the face split and interlaced circuitry shows that the face split evaporator performs better at uniform flow conditions, whereas the interlaced evaporator performs better at flow maldistribution conditions. When compensating, the face split evaporator always performs best. A similar result is also obtained as the airflow profile across the A-coil evaporator was predicted by means of CFD simulation software STAR-CD 3.26 (2005) and applied in the numerical model. The main reason for the better face split evaporator performance at uniform conditions or when compensating, is that the superheated "weak" zones with low UA-value is located in the first tube row, where the heat transfer driving potential (temperature difference) is highest. The discontinuous liquid injection principle showed that the cycle time is an important parameter for the performance of this compensation method. The cycle time is essentially the time it takes for distributing mass flow to each evaporator channels. It should be kept as low as possible. Furthermore, it is bett

  2. Degradation of finned tubes heat exchangers in presence of non condensable gases and aerosols

    International Nuclear Information System (INIS)

    Full text of publication follows: If a severe accident occurs in a nuclear power plant, then large amounts of steam and aerosols will enter to the containment, increasing the pressure and the temperature inside the containment building. To reduce these thermal and pressure loads, the next generation of European Passive Nuclear Power Plants, incorporates into the containment passive heat exchangers (HX) driven by natural circulation. These passive HX condense the steam inside the containment and transport by natural circulation the heat to a large pool with capability to act as a heat sink at least during 72 hours. These innovative passive systems consist of several units of horizontal or slightly inclined finned tubes bundles internally cooled by water. The cooling water is heated inside the tubes by the condensation heat removed from the containment and moves by natural circulation to a large pool located outside the containment. The main problem that arises in this kind of HX, is the degradation in the heat transfer produced by the non-condensable gases and the aerosols that are present in large amounts after a severe accident inside the containment. This degradation can increase the containment loads after a severe accident and we must be able to predict this effect as better as possible. This paper presents a mechanistic model to predict the steam condensation on containment finned tube heat exchangers in the presence of non-condensable gases (NC) and aerosols. Thon-condensable gases (NC) and aerosols. The total thermal resistance from the bulk gas to the coolant is formulated as a parallel combination of the convective and condensation gas resistances coupled in series to those of condensate layer, the aerosol fouling layer, the wall, and the coolant. The condensate layer thermal resistance is calculated by means of an Adamek-based condensation model. The aerosol fouling layer is computed based on diffusiophoresis, settling and impaction mechanisms. The gas mixture (Steam plus NC) thermal resistance is formulated based on a diffusion layer modeling. Finally this paper presents a Monte Carlo method implemented in the Fortran code TAEROSOL that is able to compute the amount of aerosol mass that is deposited by impaction on the top of the finned tubes. The model results are compared with available experimental data of the CONGA European project. Finally we want to mention that Monte Carlo calculations and fluid flow calculations with the code TAEROSOL were performed to compute the amount of aerosols deposited on the top of the fins by impaction during the aerosol phase of Suckow et al. experiments. Also we compute the aerosol mass deposited by diffusiophoresis and settling. The calculations performed show that the mass deposited by settling is always smaller than 3 g in all the cases, and that impaction and diffusiophoresis mechanisms are the main deposition mechanisms for aerosols in CONGA experiments. (authors)

  3. Steam generator tube performance

    International Nuclear Information System (INIS)

    A survey of steam generator operating experience for 1986 has been carried out for 184 pressurized water and pressurized heavy-water reactors, and 1 water-cooled, graphite-moderated reactor. Tubes were plugged at 75 of the reactors (40.5%). In 1986, 3737 tubes were plugged (0.14% of those in service) and 3148 tubes were repaired by sleeving. A small number of reactors accounted for the bulk of the plugged tubes, a phenomenon consistent with previous years. For 1986, the available tubesheet sludge data for 38 reactors has been compiled into tabular form, and sludge/deposit data will be incorporated into all future surveys

  4. Burnout experiments on the externally-finned swirl tube for steady-state and high-heat flux beam stops

    International Nuclear Information System (INIS)

    An experimental study to develop beam stops for the next generation of neutral beam injectors was started, using an ion source developed for the JT-60 neutral beam injector. A swirl tube is one of the most promising candidates for a beam stop element which can handle steady-state and high-heat flux beams. In the present experiments, a modified swirl tube, namely an externally-finned swirl tube, was tested together with a simple smooth tube, an externally finned tube, and an internally finned tube. The major dimensions of the tubes are 10 mm in outer-diameter, 1.5 mm in wall thickness, 15 mm in external fin width, and 700 mm in length. The burnout heat flux (CHF) normal to the externally finned swirl tube was 4.1±0.1 kW/cm2, where the Gaussian e-folding half-width of the beam intensity distribution was about 90 mm, the flow rate of the cooling water was 30 l/min, inlet and outlet gauge pressures were about 1 MPa and 0.2 MPa, respectively, and the temperature of the inlet water was kept to 200C during a pulse. A burnout heat flux ratio, which is defined by the ratio of the CHF value of the externally-finned swirl tube to that of the externally-finned tube, turned out to be about 1.5. Burnout heat fluxes of the tubes with a swirl tape or internal fins increase linearly with an increase of the flow rate. It was found that the tube with external fins has effects that not only reduce the thermal stress but also improve the characteristics of boiling h improve the characteristics of boiling heat transfer. (orig.)

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

    International Nuclear Information System (INIS)

    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.

  6. Flexible nanoscale high-performance FinFETs.

    Science.gov (United States)

    Torres Sevilla, Galo A; Ghoneim, Mohamed T; Fahad, Hossain; Rojas, Jhonathan P; Hussain, Aftab M; Hussain, Muhammad Mustafa

    2014-10-28

    With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics. PMID:25185112

  7. Propulsive performance of oscillating batoid-inspired fins

    Science.gov (United States)

    Quinn, Daniel; Rein-Weston, Daphne; Dewey, Peter; Green, Melissa; Smits, Alexander

    2009-11-01

    Thrust producing ray-like pectoral fins were actuated to drive a low friction carriage through a stationary tow tank. A DC servo motor powered a gear train that produced a traveling wave motion along the chord of the fin. The amplitude of the traveling wave increased linearly along the span from root to tip. A digital optical encoder attached to the carriage tracked the position and velocity as it was propelled through the water by the oscillating fin. Velocity profiles were acquired from trials using different planforms inspired by members of the eagle ray family, as well as an idealized elliptical fin. Traveling wave frequency and wavelength were varied to investigate the propulsive performance of different gaits. Preliminary flow visualization was also performed to describe the structure of the wakes generated by the various planform geometries and locomotory gaits.

  8. Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangers

    Science.gov (United States)

    Taler, Dawid; Sury, Adam

    2011-12-01

    The aim of the paper is a steady-state inverse heat transfer problem for plate-fin and tube heat exchangers. The objective of the process control is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Two control techniques were developed. The first is based on the presented mathematical model of the heat exchanger while the second is a digital proportional-integral-derivative (PID) control. The first procedure is very stable. The digital PID controller becomes unstable if the water volumetric flow rate changes significantly. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments showed that the PID controller works also well but becomes frequently unstable.

  9. In-service inspection method for low-finned ferritic stainless steel tubes for new heat exchanger

    International Nuclear Information System (INIS)

    Conventional inner eddy current test cannot obtain sufficient evaluation for low finned ferritic stainless steel tube inspection. The authors tried various methods and developed special partial saturation eddy current method. This paper summarizes typical experimental results of fundamental studies and trials, and introduces developed ECT data acquisition and evaluation system. Moisture Separator Heater (MSH) used in ABWR (Advanced Boiling Water Reactor) plant is a new type heat exchanger to increase plant thermal efficiency. There are four single tubesheet heaters in a MSH vessel. Each heater has hundreds of low finned tubes made of ferritic stainless steel. In nuclear power plants, non-magnetic materials (austenitic stainless steel, titanium, aluminum brass, etc.,) are mainly used as heat exchanger tubes such as the tubes of feedwater heater, condenser, evaporator and so on. Conventional ECT (Eddy Current Test) method are easily applied for the inspection of these heat exchanger tubes. In recent years, the authors started using ferritic stainless steel tube for new heat exchangers such as MSH because of its superior heat transfer efficiency. However, high permeability of ferritic stainless steel prevents the inspection of these tubes using conventional ECT method. To inspect MSH tubes periodically is important to confirm and maintain reliability of MSH. They tried applying various inspection methods and have developed special ECT method for low finned ferritic stainl ECT method for low finned ferritic stainless steel tubes

  10. Experimental testing of the thermal performance of finned air coolers

    International Nuclear Information System (INIS)

    Finned heat exchangers are often used as regenerators in heat recovery systems or as a heat source for heat pump installations. These exchangers are usually operating as air coolers. Heat is extracted from the air flowing through the heat exchanger. If the fin temperature lies below the dew point at the air inlet, water vapour may be condensed, increasing the thermal performance of the cooler. If the air/water heat exchanger is installed outdoors, the blower is usually mounted directly at the exchaner's case. In general this leads to non-ideal air flow conditions. For the sizing of such components the manufacturers dispose of design rules which are based either on theoretical models or on experiments using a uniform air stream. These rules which are mostly internal codes of the individual companies presumably do not take into account some non-ideal conditions such as an inhomogeneous air flow, a poorly sized blower or an increased pressure drop between the fins due to condensed water vapour. Moreover, these codes are possibly not sophisticated enough to enable a correct sizing of the products for any given condition of operation, especially in heat pumps operating under condensation conditions. Therfore, the Swiss Federal Institute for Reactor Research (EIR) carried out a research program dealing with the thermal performance of commercially available finned air coolers. The results give a strong evidence that the sizing of finned air coolers involving a phase change in one of the heat transfer fluids is not yet a procedure belonging to the common knowledge of most of the manufacturers. Moreover, the correct sizing of the blower is at least as important as the sizing of the finned exchanger itself. However, it is evident that there are companies on the Swiss market which use already reliable design tools. 25 refs., 81 figs., 12 tabs

  11. Beneficial design of unbaffled shell-and-tube heat exchangers for attachment of longitudinal fins with trapezoidal profile

    Directory of Open Access Journals (Sweden)

    Balaram Kundu

    2015-03-01

    Full Text Available A parametric variation followed with Kern’s method of design of extended surface heat exchanger has been made for an unbaffled shell-and-tube heat exchanger problem. For this analysis, the rectangular and trapezoidal fin shapes longitudinally attached to the fin tubes are taken. In comparison with the attachment of trapezoidal fins, it is found that the heat transfer rate was lesser than the rectangular cross section by keeping a constant outer diameter of the shell along with all other constraints of a heat exchanger design, namely, number of passes, tube outer diameter, tube pitch layout, etc. But when the total volume of the fin over a tube was kept constraint, using trapezoidal fins the heat transfer rate is found to be increased and consequently the pressure drop decreases much more than in the case of fins with rectangular cross section. This optimization has shown beneficial results in all the cases of different constraints of heat exchanger design analysis.

  12. Experimental investigation of forced-convection in a finned rhombic tube of the flat-plate solar collectors

    DEFF Research Database (Denmark)

    Taherian, Hessam; Yazdanshenas, Eshagh

    2006-01-01

    Due to scarcity of literature on forced-convection heat transfer in a solar collector with rhombic cross-section absorbing tubes, a series of experiments was arranged and conducted to determine heat transfer coefficient. In this study, a typical rhombic cross-section finned tube of flat-plate collectors used as the test section. Two correlations were proposed for the Nusselt number as a function of the Reynolds number and the Prandtl number based on hydraulic diameter for various heat fluxes. The temperature distribution along the finned tube for the fluid and the wall were also illustrated.

  13. Heat transfer from a horizontal finned tube bundle in bubbling fluidized beds of small and large particles

    Energy Technology Data Exchange (ETDEWEB)

    Devaru, C.B. [Jayachamaraja College of Engineering, Mysore (India). Dept. of Mechanical Engineering; Kolar, A.K. [Indian Inst. of Technology, Madras (India). Dept. of Mechanical Engineering

    1995-12-31

    Steady state average heat transfer coefficient measurements were made by the local thermal simulation technique in a cold, square, bubbling air-fluidized bed (0.305 m x 0.305 m) with immersed horizontal finned tube bundles (in-line and staggered) with integral 60{degree} V-thread. Studies were conducted using beds of small (average particle diameter less than 1 mm) sand particles and of large (average particle diameter greater thin 1 mm) particles (raagi, mustard, millet and coriander). The fin pitch varied from 0.8 to 5.0 mm and the fin height varied from 0.69 to 4.4 mm. The tube pitch ratios used were 1.75 and 3.5. The influence of bed particle diameter, fluidizing velocity, fin pitch, and tube pitch ratio on average heat transfer coefficient was studied. Fin pitch and bed particle diameter are the most significant parameters affecting heat transfer coefficient within the range of experimental conditions. Bed pressure drop depends only on static bed height. New direct correlations, incorporating easily measurable quantities, for average heat transfer coefficient for finned tube bundles (in-line and staggered) are proposed.

  14. Effect of surface treatments on the frosting/defrosting behavior of a fin-tube heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Sung Jhee [Hanyang Univ., Seoul (Korea). Graduate School, Dept. of Mechanical Engineering; Kwan Soo Lee; Woo Seung Kim [Hanyang Univ., Seoul (Korea). School of Mechanical Engineering

    2002-12-01

    The effects of the heat exchanger surface treatment on the frosting/defrosting behavior in a fin-tube heat exchanger are investigated experimentally. It is found that the hydrophilic surface mainly influences the frosting behavior, while the hydrophobic surface has some influence on the defrosting behavior. In view of the frosting, a surface-treated heat exchanger with either hydrophilic or hydrophobic characteristic shows little improvement in the thermal performance rather than the bare aluminum heat exchanger. The results reveal that the heat exchanger with a hydrophobic surface treatment is more effective in view of the defrosting efficiency and time. The amount of residual water on the surface-treated heat exchangers is shown to be smaller than that of the bare heat exchanger. Therefore further improvements on the performance of re-operations are expected. (Author)

  15. Experimental Study of Heat Transfer Enhancement in Fin Tube Heat Exchanger by Vortex Generator-A Review

    OpenAIRE

    Dhananjay Kumar*1; Prof. Alok choube2

    2014-01-01

    This review paper presents the work of various researchers on the heat transfer enhancement of fin tube heat exchanger. In this research author used different type of vortex generator like delta winglet, rectangular winglet, curved trapezoidal winglet pair. The vortex generator can be embedded in the plate fin and that too in a low cost with effect the original design and setup of the commonly used heat exchangers. The various design modifications which are implemented and stu...

  16. Comparison of fin-and-tube interlaced and face split evaporators with flow mal-distribution and compensation

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2011-01-01

    Flow mal-distribution in fin-and tube evaporators for residential air-conditioning is investigated by numerical simulation. In particularly, the interlaced and the face split evaporator are compared in flow maldistribution conditions. The considered sources of mal-distribution are: Liquid/vapor distribution and airflow distribution. Furthermore, compensation of flow mal-distribution by control of individual channel superheat is studied for each type of evaporator. It is shown that the interlaced evaporator is better at flow maldistribution than the face split evaporator. However, if individual channel superheats are controlled, the face split evaporator achieves the best performance, i.e. an increase of 7% in UA-value and 1.6% to 2.4% in COP compared to the interlaced evaporator without compensation.

  17. Volume Averaging Theory (VAT) based modeling and closure evaluation for fin-and-tube heat exchangers

    Science.gov (United States)

    Zhou, Feng; Catton, Ivan

    2012-10-01

    A fin-and-tube heat exchanger was modeled based on Volume Averaging Theory (VAT) in such a way that the details of the original structure was replaced by their averaged counterparts, so that the VAT based governing equations can be efficiently solved for a wide range of parameters. To complete the VAT based model, proper closure is needed, which is related to a local friction factor and a heat transfer coefficient of a Representative Elementary Volume (REV). The terms in the closure expressions are complex and sometimes relating experimental data to the closure terms is difficult. In this work we use CFD to evaluate the rigorously derived closure terms over one of the selected REVs. The objective is to show how heat exchangers can be modeled as a porous media and how CFD can be used in place of a detailed, often formidable, experimental effort to obtain closure for the model.

  18. Experimental and numerical investigation of a louvered fin and elliptical tube compact heat exchanger

    Directory of Open Access Journals (Sweden)

    Pooranachandran Karthik

    2015-01-01

    Full Text Available In the present work, an experimental investigation is carried out to analyze the heat transfer characteristics of a louvered fin and elliptical tube compact heat exchanger used as a radiator in an internal combustion engine. Experiments are conducted by positioning the radiator in an open-loop wind tunnel. A total of 24 sets of air, water flow rate combinations are tested, and the temperature drops of air and water were acquired. A numerical analysis has been carried out using Fluent software (a general purpose computational fluid dynamics simulation tool for three chosen data from the experiments. The numerical air-side temperature drop is compared with those of the experimental values. A good agreement between the experimental and numerical results validates the present computational methodology.

  19. A study of defrosting behavior according to surface characteristics in a fin-tube heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.S.; Kim, J.M.; Jhee, S. [Hanyang University, Seoul (Korea)

    1999-11-01

    In this study, the defrosting behaviors according to the surface characteristics in the fin-tube heat exchanger is experimentally examined. It is found that the draining rate of the hydrophilic and hydrophobic heat exchangers are evenly dispersed during defrosting, compared with that of the bare one. It is caused by the high density frost for the hydrophilic heat exchanger, and surface characteristic for the hydrophobic heat exchanger, respectively. The rest period of the hydrophilic and hydrophobic heat exchangers are shorter and their weight of residual water are smaller than those of the bare heat exchanger. The hydrophilic and hydrophobic heat exchangers are more effective than the bare one in terms of defrosting efficiency, and the hydrophobic heat exchanger is better than the hydrophilic one. 8 refs., 7 figs.

  20. Pressure drop coefficients for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers

    Scientific Electronic Library Online (English)

    Sérgio Nascimento, Bordalo; Francisco Eduardo Mourão, Saboya.

    1999-12-01

    Full Text Available The objective of the present work is the experimental determination of pressure drop coefficients (loss coefficients) for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers. The experiments permitted to correlate the dimensionless loss coeffic [...] ient with the flow Reynolds number in the rectangular channel formed by the plate fins. The experimental technique consisted of the measurement of the longitudinal pressure distribution along the flow channel, for several values of air mass flow rate. The total number of data runs, each one characterized by the flow Reynolds number, was 216. The present geometry is used in compact heat exchangers for air conditioning systems, heaters, radiators, and others. Also, it is verified the influence of the utilization of elliptic tubes, instead of circular ones, in the pressure drop. The measurements were performed for Reynolds numbers ranging from 200 to 1900.

  1. How can the heat transfer correlations for finned-tubes influence the numerical simulation of the dynamic behavior of a heat recovery steam generator?

    International Nuclear Information System (INIS)

    This paper presents the results of a theoretical investigation on the influence of different heat transfer correlations for finned-tubes to the dynamic behavior of a heat recovery steam generator (HRSG). The investigation was done for a vertical type natural circulation HRSG with 3 pressure stages under hot start-up and shutdown conditions. For the calculation of the flue gas-side heat transfer coefficient the well known correlations for segmented finned-tubes according to Schmidt, VDI and ESCOATM (traditional and revised) as well as a new correlation, which was developed at the Institute for Energy Systems and Thermodynamics, are used. The simulation results show a good agreement in the overall behavior of the boiler between the different correlations. But there are still some important differences found in the detail analysis of the boiler behavior. - Research highlights: ? Numerical simulation is performed to explore the influence of different heat transfer correlations for finned-tubes to the dynamic behavior of a heat recovery steam generator. ? Differences in the steam generator behavior are found. ? In the worst case the boiler can lead to unfavorable operation conditions, e.g. reverse flow.

  2. 3D-CFD simulation and neural network model for the j and f factors of the wavy fin-and-flat tube heat exchangers

    Scientific Electronic Library Online (English)

    M, Khoshvaght Aliabadi; M, Gholam Samani; F, Hormozi; A, Haghighi Asl.

    2011-09-01

    Full Text Available A three dimensional (3D) computational fluid dynamics (CFD) simulation and a neural network model are presented to estimate the behaviors of the Colburn factor (j) and the Fanning friction factor (f) for wavy fin - and - flat tube (WFFT) heat exchangers. Effects of the five geometrical factors of fi [...] n pitch, fin height, fin length, fin thickness, and wavy amplitude are investigated over a wide range of Reynolds number (600

  3. Operating performance of CANDU pressure tubes

    International Nuclear Information System (INIS)

    The performance of Zircaloy-2 and Zr-2.5 Nb pressure tubes in CANDU reactors is reviewed. The accelerated hydriding of Zircaloy-2 in reducing water chemistries can lower the toughness of this material and it is essential that defect-initiating phenomena, such as hydride blister formation from pressure tube to calandria tube contact, be prevented. Zr-2.5 Nb pressure tubes are performing well with low rates of hydrogen pick-up and good retention of material properties

  4. Non-Destructive Testing Methods Applied to Multi-Finned SAP Tubing for Nuclear-Fuel Elements

    International Nuclear Information System (INIS)

    The Danish Atomic Energy Commission has undertaken a design study oi an organic-cooled, heavy- water-moderated power reactor. The fuel element for the reactor is a 19-rod bundle; the fuel rods contain sintered uranium-dioxide pellets canned in 2-m long, helically-finned tubes of Sintered Aluminium Product (SAP). A very high quality of the canning tubes is necessary to obtain the optimum heat-transfer conditions and to maintain the integrity of the fuel element during reactor service. Two examples of tube design illustrate the narrow dimensional tolerances. In order to ensure an adequate quality of the canning tubes, a stringent quality control has been established, to a wide extent based upon non-destructive methods. An account is presented of the non-destructive techniques developed for measuring wall thickness and diameters and for detecting defects. The complex 24-finned cross-section prevents the application of ultrasonic or eddy-current methods for wall-thickness measurements. Therefore, a special recording beta-gauge has been developed, based upon the attenuation of beta radiation from a Sr90 source placed inside the tube. An ultrasonic immersion resonance method is used for the continuous recording of the wall thickness of the more simple 12-finned tube design. Inner and outer (across fin tips) diameters are continuously recorded by rapid air-gauge systems. Flaw detection is carried out by the ultrasonic pulse-echo immersion technique and by eddy-cure-echo immersion technique and by eddy-current inspection.. Transverse cracks can easily be detected by the ultrasonic method whereas inspection for longitudinal flaws has not appeared feasible with this method. Therefore, eddy-current inspection is applied in addition to the ultrasonic testing. (author)

  5. Studi Eksperimen Analisa Performa Compact Heat Exchanger Circular Tubes Continuous Plate Fin Untuk Pemanfaatan Waste Energy

    Directory of Open Access Journals (Sweden)

    Rachmadi Gewa Saputra

    2014-03-01

    Full Text Available Harga minyak dunia cenderung mengalami peningkatan dalam beberapa tahun terakhir sehingga manusia berfikir untuk memanfaatkan setiap penggunaan minyak bumi. Dengan berkembangnya teknologi saat ini waste energy yang berupa gas hasil pembakaran pada engine dapat dimanfaatkan menjadi bentuk energi lain menggunakan heat recovery system. Pada tugas akhir ini dilakukan desain sebuah heat exchanger tipe circular tubes continuous plate fin dengan susunan tube aligned yang digunakan untuk menyerap waste energy yang berupa exhaust gas. Untuk mendapatkan dimensi desain yang sesuai digunakan metode ?TLMTD. Metode ini digunakan untuk menentukan nilai dari overall heat transfer  desain dari heat exchanger, kemudian dilakukan perhitungan untuk nilai overall heat transfer hitung. Setelah didapatkan nilai dari overall heat transfer secara desain dan hitung maka dilakukan iterasi untuk mendapatkan dimensi heat exchanger yang memiliki nilai error paling kecil antara nilai overall heat transfer desain dan hitung. Untuk pengujian performa dari heat exchanger yang telah didesain maka dilakukan variasi kacepatan exhaust gas yang melewati heat exchanger, yaitu 0.4 m/s, 0.3 m/s, dan 0.2 m/s. Exhaust gas yang digunakan memiliki temperatur 280oC. Pada tugas akhir ini didapatkan desain compact heat exchanger dengan dimensi panjang 0.38 m, lebar 0.45 m, dan tebal 0.04m. Setelah dilakukan pengujian dengan memvariasikan kecepatan dari exhaust gas yang melewati heat exchanger maka didapatkan bahwa nilai dari qaktual dari heat exchanger mengalami kenaikan dengan bertambahnya reynolds number akibat bertambahnya kecepatan exhaust gas, kemudian nilai dari effectiveness akan mengalami penurunan untuk setiap kenaikan dari reynold number exhaust gas. Selain itu nilai dari NTU heat exchanger juga mengalami penurunan dengan bertambahnya reynold number exhaust gas. Untuk nilai overall heat transfer dari heat exchanger yang didesain akan mengalami kenaikan akibat bertambahnya nilai reynold number exhaust gas.

  6. Steam generator tubing NDE performance

    International Nuclear Information System (INIS)

    Steam generator (SG) non-destructive examination (NDE) is a fundamental element in the broader SG in-service inspection (ISI) process, a cornerstone in the management of PWR steam generators. Based on objective performance measures (tube leak forced outages and SG-related capacity factor loss), ISI performance has shown a continually improving trend over the years. Performance of the NDE element is a function of the fundamental capability of the technique, and the ability of the analysis portion of the process in field implementation of the technique. The technology continues to improve in several areas, e.g. system sensitivity, data collection rates, probe/coil design, and data analysis software. With these improvements comes the attendant requirement for qualification of the technique on the damage form(s) to which it will be applied, and for training and qualification of the data analysis element of the ISI process on the field implementation of the technique. The introduction of data transfer via fiber optic line allows for remote data acquisition and analysis, thus improving the efficiency of analysis for a limited pool of data analysts. This paper provides an overview of the current status of SG NDE, and identifies several important issues to be addressed

  7. Steam generator tubing NDE performance

    Energy Technology Data Exchange (ETDEWEB)

    Henry, G. [Electric Power Research Institute, Charlotte, NC (United States); Welty, C.S. Jr. [Electric Power Research Institute, Palo Alto, CA (United States)

    1997-02-01

    Steam generator (SG) non-destructive examination (NDE) is a fundamental element in the broader SG in-service inspection (ISI) process, a cornerstone in the management of PWR steam generators. Based on objective performance measures (tube leak forced outages and SG-related capacity factor loss), ISI performance has shown a continually improving trend over the years. Performance of the NDE element is a function of the fundamental capability of the technique, and the ability of the analysis portion of the process in field implementation of the technique. The technology continues to improve in several areas, e.g. system sensitivity, data collection rates, probe/coil design, and data analysis software. With these improvements comes the attendant requirement for qualification of the technique on the damage form(s) to which it will be applied, and for training and qualification of the data analysis element of the ISI process on the field implementation of the technique. The introduction of data transfer via fiber optic line allows for remote data acquisition and analysis, thus improving the efficiency of analysis for a limited pool of data analysts. This paper provides an overview of the current status of SG NDE, and identifies several important issues to be addressed.

  8. A three-dimensional numerical study and comparison between the air side model and the air/water side model of a plain fin-and-tube heat exchanger

    International Nuclear Information System (INIS)

    CFD is becoming an important heat exchanger research technique. It constitutes an inexpensive prediction method, avoiding the need of testing numerous prototypes. Current work in this field is mostly based on air flow models assuming constant temperature of fin-and-tube surface. The purpose of this paper is to present an enhanced model, whose innovation lies in considering additionally the water flow in the tubes and the conduction heat transfer through the fin and tubes, to demonstrate that the neglect of these two phenomena causes a simulation result accuracy reduction. 3-D Numerical simulations were accomplished to compare both an air side and an air/water side model. The influence of Reynolds number, fin pitch, tube diameter, fin length and fin thickness was studied. The exchanger performance was evaluated through two non-dimensional parameters: the air side Nusselt number and a friction factor. It was found that the influence of the five parameters over the mechanical and thermal efficiencies can be well reported using these non-dimensional coefficients. The results from the improved model showed more real temperature contours, with regard to those of the simplified model. Therefore, a higher accuracy of the heat transfer was achieved, yielding better predictions on the exchanger performance.

  9. Air-side thermal hydraulic performance of an integrated fin and micro-channel heat exchanger

    International Nuclear Information System (INIS)

    An integrated fin and micro-channel heat exchanger has been proposed. For 11 heat exchanger samples with different flow depth, fin height, fin pitch and fin thickness, a series of tests were conducted to determine their effect on the air-side thermal hydraulic performance. The heat transfer coefficient and pressure drop for heat exchangers with different geometrical configurations were reported in terms of Colburn factor j and Fanning friction factor f, as functions of Reynolds number. The general correlations for j and f factors were derived and can predict 96% and 92% of the experimental data, within rms errors of ±10% and ±12%, respectively. The air-side heat transfer and flow characteristics of the integrated fin were compared with that of the multi-louver fin and the wavy fin.

  10. An experimental study of defrosting behaviors on the fin-tube heat exchanger with PTC heating sheet

    Energy Technology Data Exchange (ETDEWEB)

    Jhee, S.; Lee, K.S. [Hanyang University, Seoul (Korea)

    1999-01-01

    In this work, the defrosting characteristics of PTC heating sheet used as a defrosting heat source of fin-tube heat exchanger in a refrigerator have been experimentally compared with those of conventional electric heater. It is found that the characteristics of water draining rate with defrosting time show smoothly oscillating pattern when PTC heating sheet is used, and the drained water is completely melted. The defrosting efficiency of the PTC heating sheet is about 75%, which represents about 25% higher than that of the electric heater. A reduction of defrosting time and an increase of defrosting efficiency may be obtained by improving the arrangement of heating elements of the heating sheet. It is shown that the defrosting time of PTC heating sheet increases linearly with the amount of frost, however the defrosting efficiency is nearly constant. In the application to the refrigerating system, one should notice the fact that the defrosting performance of PTC heating sheet may be defraded due to the repeated operations. 13 refs., 9 figs.

  11. The effect of surface contact angle on the behavior of frost formation in the fin-tube heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.S. [Hanyang University, Seoul (Korea); Jhee, S.; Lee, D.W. [Hanyang University, Graduate School, Seoul (Korea)

    1999-11-01

    The effect of surface contact angle on the behavior of frost formation in the fin-tube heat exchanger is investigated experimentally. It is shown that both heat exchangers with hydrophilic and hydrophobic surfaces appear to have a better thermal performance than bare aluminium heat exchanger, but the improvements are very small. There is a little increase in the amount of the frost deposited onto the heat exchanger with both hydrophilic and hydrophobic surface. However, the effect of contact angle on the frost density is observed : the frost with high density forms on the heat exchanger with hydrophilic surface : and the frost with low density is deposited onto the heat exchanger with hydrophobic surface when compared with the frost deposited onto the heat exchanger with bare aluminium surface. This may be attributed to the fact that the shape of water droplets which condense on the surface of heat exchanger at the early stage of frosting varies with contact angle, and thus makes a difference on the structure of frost formation. From the experiments with different relative humidity of inlet air, it is shown that the variations of operating parameter make no influence on the effect of surface contact angle on the frosting behavior in the heat exchanger. (author). 10 refs., 9 figs.

  12. The impact of fin profile and interface condition on performance characteristics of heat sinks

    International Nuclear Information System (INIS)

    Thermal management of electronic products relies mainly on the effective dissipation of heat. Heat sinks (containing multiple extended surfaces or fin array) are commonly used for heat dissipation network. The performance of an individual fin depends on its geometry, material properties and operating environment (i.e. free or forced convection). In the first part of this paper, the four most commonly used fin profiles are studied for pin, longitudinal and annular fins using non-dimensional finite element formulation. In the second part, the performance of different thermal interfaces is studied for polymer and metallic fins. Polymer composite materials result in significant increase in the performance of a fin; however manufacturing can be a constraint to construct an effective heat sink due to interface conditions at the fin and base plate junction. It is found that the joint at fin base plate has considerable stress effect in the heat sink system. The press fit joint must have high contact pressure to maintain an appropriate thermal contact conductance (TCC) in order to have thermal performance comparable to an adhesive joint, but the two joints have different state of thermal and contact stresses. -- Highlights: ? The effect of fin profile on performance for pin, longitudinal and annular fins is studied. ? The significant effect is found only for pin fins under considered conditions. ? The effect of interface at orthotropic pin fin and metallic base plate is studied. ? Two interface conditions called epoxy-bonded and press-fitted are studied. ? The contact pressure and stresses decrease at high temperature for press-fitted interface

  13. Ideal orifice pulse tube refrigerator performance

    Science.gov (United States)

    Kittel, P.

    1992-01-01

    The recent development of orifice pulse tube refrigerators has raised questions as to what limits their ultimate performance. Using an analogy to the Stirling cycle refrigerator, the efficiency (cooling power per unit input power) of an ideal orifice pulse tube refrigerator is shown to be T1/T0, the ratio of the cold temperature to the hot temperature.

  14. Verification of the performance of impact limiting FINS-II

    International Nuclear Information System (INIS)

    Atomic Energy Control Board (AECB) repeated drop test experiments, by Oak Ridge National Laboratories (ORNL) in 1971, to: a) investigate the influence of impact velocity in order to determine whether it was a cause of the difference between the two sets of curves, and b) extend the range of application of the design curves; specifically to higher deformation, to stainless steel material, and to non-square (oblique) impact conditions. Using the same drop test facility, instrumentation and experimental procedure as the previous study, data were collected from 272 specimens. These were primarily of the single fin type, similar to the ORNL design; only the oblique impact test specimens had a special double fin configuration. Results from the impact velocity tests showed that while this did influence the shape of the first part of the curves, it did not explain the difference in magnitude between the two sets of curves. Changing the fin material to type 304 stainless steel showed that for vertical fins essentially the same curves were obtained. However, for the 30 degree inclined specimens, the stainless steel fins showed lower energy absorption capabilities. Measurements from the high deformation tests indicated that there is no tendency for the curves to change slope at the higher deformations. The oblique impact tests attempted to extend the application of the design curves to a 'one end first' type of container impact condition. Results confirmed expected higher values of deformation per input (energy/fin width), but there was no correlation between the curves for normal impact conditions and those for oblique impact conditions

  15. Evaluación de Intercambiadores de Calor Compactos de Tubos Aletados / Evaluation of Compact Finned-Tube Heat Exchangers

    Scientific Electronic Library Online (English)

    M.T., Martínez; E., Torres; J.A., Soto.

    Full Text Available En este trabajo, se presenta el análisis térmico teórico de un intercambiador de calor compacto, con y sin condensación de agua en el lado del aire. El fenómeno de la condensación del vapor de agua en la corriente de aire entrante produce una película de agua en la superficie cubriéndola en forma pa [...] rcial o completa. El análisis considera varias configuraciones geométricas con respecto a: la superficie de las aletas y a la forma de los tubos considerando la forma circular tradicional y también un caso para tubos planos. Los resultados obtenidos reflejan la eficiencia de la aleta en ambos casos: una aleta totalmente seca (sin condensación) y a una totalmente húmeda es decir, totalmente cubierta por la película de condensado. Se concluye que la metodología propuesta es una buena alternativa de análisis y caracterización de un intercambiador, ya que los resultados obtenidos coinciden con los reportados en la literatura Abstract in english This study presents a theoretical thermal analysis of a compact heat exchanger, with and without water condensation on the air side. The phenomenon of condensation of water vapor in the entering air current produces a film of water on the surface, partially or completely covering the surface. The an [...] alysis considers various geometric configurations with respect to the surfaces of the fins and the form of the tubes, including the traditional round form as well as flattened tubes. The results obtained reflect the efficiency of the fins in both cases , including a completely dry fin (no condensation) and a completely wet fin, that is completely covered with a film of condensate. It is concluded that the methodology proposed is a good alternative for the analysis and characterization of a heat exchanger since the results agree with those reported in the literature

  16. Alloy 800 steam generator tube performance

    International Nuclear Information System (INIS)

    This paper reviews the reasoning behind the selection of Alloy 800 nuclear grade (800NG) for tubing of steam generators in pressurized water reactor (PWR) plants designed by Siemens/Kraftwerk Union (KWU) (now AREVA) and pressurized heavy water reactor (PHWR) plants designed by Atomic Energy of Canada Limited (AECL). The PWR and PHWR plants where Alloy 800NG is used are identified. The very good operating performance of the steam generator tubes in these plants is described. The limited numbers of tubes removed from service due to indications of tube degradation in these plants are described, and the probable causes and possible future progression of the tube degradation modes involved are discussed. (author)

  17. An analytical prediction for performance and optimum design analysis of porous fins

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Balaram [Department of Mechanical Engineering, Jadavpur University, Kolkata 700 032 (India); School of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Sungdong-gu, Seoul 133-791 (Korea, Republic of); Bhanja, Dipankar [Department of Mechanical Engineering, Jadavpur University, Kolkata 700 032 (India)

    2011-01-15

    Enhancement of heat transfer rate through porous fins is one of the common choices nowadays. As the energy equation is highly nonlinear, researchers never concentrated on analyzing porous fins analytically. In the present study, an effort has been devoted to develop an analytical model for determination of the performance and optimum dimensions of porous fins with consideration of different models of predictions. Every result has been presented in a comparative way so that the merit of the models adopting in the present work can easily be understood. The optimum design analysis of porous fins has also been carried out. The influences of all the dependent parameters on the performances and optimization conditions have been studied for the selection of a design criterion of porous fins in such applications where the requirement of heat dissipation is essentially high. (author)

  18. An experimental study of the surface treatment effect on the frosting/defrosting behavior of a fin-tube heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Jhee, S. [Hanyang University Graduate School, Seoul (Korea); Lee, K.S. [Hanyang University, Seoul (Korea)

    2000-08-01

    The effect of heat exchanger surface treatment on the frosting/defrosting behavior in a fin-tube heat exchanger is investigated experimentally. It is found that the hydrophilic surface mainly influences on the frosting behavior, however, the hydrophobic surface gives some influence on the defrosting behavior. In view of frosting performance, surface-treated heat exchanger with either hydrophilic or hydrophobic characteristic shows a little improvement in the thermal performance than the aluminium heat exchanger with no surface treatment. The result reveals that the heat exchanger with hydrophobic surface treatment is more effective in view of the defrosting efficiency and time. The amounts of residual water on the surface-treated heat exchangers are shown to be smaller than those of the bare heat exchanger, therefore further improvements on the performance of re-operations are expected. (author). 14 refs., 7 figs.

  19. Indoor solar thermal energy saving time with phase change material in a horizontal shell and finned-tube heat exchanger.

    Science.gov (United States)

    Paria, S; Sarhan, A A D; Goodarzi, M S; Baradaran, S; Rahmanian, B; Yarmand, H; Alavi, M A; Kazi, S N; Metselaar, H S C

    2015-01-01

    An experimental as well as numerical investigation was conducted on the melting/solidification processes of a stationary phase change material (PCM) in a shell around a finned-tube heat exchanger system. The PCM was stored in the horizontal annular space between a shell and finned-tube where distilled water was employed as the heat transfer fluid (HTF). The focus of this study was on the behavior of PCM for storage (charging or melting) and removal (discharging or solidification), as well as the effect of flow rate on the charged and discharged solar thermal energy. The impact of the Reynolds number was determined and the results were compared with each other to reveal the changes in amount of stored thermal energy with the variation of heat transfer fluid flow rates. The results showed that, by increasing the Reynolds number from 1000 to 2000, the total melting time decreases by 58%. The process of solidification also will speed up with increasing Reynolds number in the discharging process. The results also indicated that the fluctuation of gradient temperature decreased and became smooth with increasing Reynolds number. As a result, by increasing the Reynolds number in the charging process, the theoretical efficiency rises. PMID:25879052

  20. Indoor Solar Thermal Energy Saving Time with Phase Change Material in a Horizontal Shell and Finned-Tube Heat Exchanger

    Science.gov (United States)

    Paria, S.; Sarhan, A. A. D.; Goodarzi, M. S.; Baradaran, S.; Rahmanian, B.; Yarmand, H.; Alavi, M. A.; Kazi, S. N.; Metselaar, H. S. C.

    2015-01-01

    An experimental as well as numerical investigation was conducted on the melting/solidification processes of a stationary phase change material (PCM) in a shell around a finned-tube heat exchanger system. The PCM was stored in the horizontal annular space between a shell and finned-tube where distilled water was employed as the heat transfer fluid (HTF). The focus of this study was on the behavior of PCM for storage (charging or melting) and removal (discharging or solidification), as well as the effect of flow rate on the charged and discharged solar thermal energy. The impact of the Reynolds number was determined and the results were compared with each other to reveal the changes in amount of stored thermal energy with the variation of heat transfer fluid flow rates. The results showed that, by increasing the Reynolds number from 1000 to 2000, the total melting time decreases by 58%. The process of solidification also will speed up with increasing Reynolds number in the discharging process. The results also indicated that the fluctuation of gradient temperature decreased and became smooth with increasing Reynolds number. As a result, by increasing the Reynolds number in the charging process, the theoretical efficiency rises. PMID:25879052

  1. Levenberg-Marquardt application to two-phase nonlinear parameter estimation for finned-tube coil evaporators

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available A procedure for calculation of refrigerant mass flow rate is implemented in the distributed numerical model to simulate the flow in finned-tube coil dry-expansion evaporators, usually found in refrigeration and air-conditioning systems. Two-phase refrigerant flow inside the tubes is assumed to be one-dimensional, unsteady, and homogeneous. In the model the effects of refrigerant pressure drop and the moisture condensation from the air flowing over the external surface of the tubes are considered. The results obtained are the distributions of refrigerant velocity, temperature and void fraction, tube-wall temperature, air temperature, and absolute humidity. The finite volume method is used to discretize the governing equations. Additionally, given the operation conditions and the geometric parameters, the model allows the calculation of the refrigerant mass flow rate. The value of mass flow rate is computed using the process of parameter estimation with the minimization method of Levenberg-Marquardt minimization. In order to validate the developed model, the obtained results using HFC-134a as a refrigerant are compared with available data from the literature.

  2. Pressure drop coefficients for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers

    OpenAIRE

    Sérgio Nascimento Bordalo; Francisco Eduardo Mourão Saboya

    1999-01-01

    The objective of the present work is the experimental determination of pressure drop coefficients (loss coefficients) for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers. The experiments permitted to correlate the dimensionless loss coefficient with the flow Reynolds number in the rectangular channel formed by the plate fins. The experimental technique consisted of the measurement of the longitudinal pressure distribution along the f...

  3. Experimental study of heat transfer and thermal performance with longitudinal fins of solar air heater

    Directory of Open Access Journals (Sweden)

    Foued Chabane

    2014-03-01

    Full Text Available The thermal performance of a single pass solar air heater with five fins attached was investigated experimentally. Longitudinal fins were used inferior the absorber plate to increase the heat exchange and render the flow fluid in the channel uniform. The effect of mass flow rate of air on the outlet temperature, the heat transfer in the thickness of the solar collector, and the thermal efficiency were studied. Experiments were performed for two air mass flow rates of 0.012 and 0.016 kg s?1. Moreover, the maximum efficiency values obtained for the 0.012 and 0.016 kg s?1 with and without fins were 40.02%, 51.50% and 34.92%, 43.94%, respectively. A comparison of the results of the mass flow rates by solar collector with and without fins shows a substantial enhancement in the thermal efficiency.

  4. Analysis of Steam Condensation in a Finned Tube of Air-Water Combined Cooling System

    International Nuclear Information System (INIS)

    A Passive Auxiliary Feedwater System (PAFS) is one of the passive cooling systems of the existing power plant and the operating period is 8 hours because of the limited capacity of the cooling water tank. Therefore, to increase the operating period from 8 to 72 hours for an existing PAFS, the capacity of the cooling water tank should be increased up to 3-4 times. To resolve the excessive increase of the cooling tank volume in water cooling systems, an air-water combined passive cooling system is proposed. In this combined cooling system, the core cooling during the initial stage of an accident having high decay power depends on the water cooling systems such as PAFS. For the later phase of an accident, an air-cooling system is applied to the core cooling. In the operation of the air-cooling system, the steam from the cooling water tank of the PAFS is condensed and recirculated to the cooling water tank by an air-cooling heat exchanger. In this way, the increase of the cooling water tank volume can be minimized. To design an air-water combined cooling system, the steam condensation characteristics of an air-cooling heat exchanger tube was calculated using a CFX code. The results show that the air velocities around the tube at the steam inlet/outlet regions are quite different with each other. Therefore, dense installation of thermocouples at the tube bottom region is required to measure the steam condensation in the tube. Otherwise, the detection and measurement of steam condensation at the steam inlet region may be very difficult. The velocity distribution of air is not uniform and the distributions of air temperature and velocity around the heat exchanger tube are strongly asymmetric. In the design of the measurement system of the test facility, the problems mentioned above should be considered

  5. Thermal performance of plate fin heat sink cooled by air slot impinging jet with different cross-sectional area

    Science.gov (United States)

    Mesalhy, O. M.; El-Sayed, Mostafa M.

    2015-06-01

    Flow and heat transfer characteristics of a plate-fin heat sink cooled by a rectangular impinging jet with different cross-sectional area were studied experimentally and numerically. The study concentrated on investigating the effect of jet width, fin numbers, and fin heights on thermal performance. Entropy generation minimization method was used to define the optimum design and operating conditions. It is found that, the jet width that minimizes entropy generation changes with heat sink height and fin numbers.

  6. Heat Transfer and Flow Characteristics of Flow Boiling of CO2-oil Mixtures in Horizontal Smooth and Micro-fin Tubes

    Science.gov (United States)

    Ono, Takashi; Gao, Lei; Honda, Tomohiro

    Experiments on flow pattern, heat transfer and pressure drop of flow boiling of pure CO2 and CO2-oil mixtures in horizontal smooth and micro-fin tubes have been carried out. The smooth tube is a stainless steel tube with an inner diameter of 3.76 mm. The micro-fin tube is a copper tube with a mean inner diameter of 3.75 mm. Experiments were carried out at mass velocities from 100 to 500 kg?(m2·s), saturation temperature of 10 °C, and the circulation ratio of lubricating oil (PAG) is from 0 to 1.0 mass%. Flow pattern observations mainly showed the slug and wavy flow for the smooth tube, but the annular flow for the micro-fin tube. As compared with flow patterns in case of pure CO2, an increase in frequency of slug occurrence in slug flow region, and a decrease in liquid amount at the top of the tube in annular flow region were observed in case of CO2-oil mixtures. For pure CO2, the flow boiling heat transfer was dominated by nucleate boiling at low vapor quality region, and the heat transfer coefficients for the micro-fin tube were higher than those of the smooth tube. For CO2-oil mixtures, the flow boiling heat transfer was dominated by convective evaporation especially at high vapor quality region. In addition, the heat transfer coefficient decreased remarkably when the oil circulation ratio was larger than 0.1 mass%. For pressure drop characteristics, in case of pure CO2, the homogeneous model agreed with the experimental results within ± 30 % for the smooth tube. The pressure drops of the micro-fin tube were 0˜70 % higher than those predicted with the homogeneous model. Furthermore, the pressure drops increased at the high oil circulation ratio and high vapor quality conditions. The increases in the pressure drops were considered due to the increase in the thickness of the oil film and the decrease in the effective flow cross-sectional area.

  7. Performance and cost benefits analysis of double-pass solar collector with and without fins

    International Nuclear Information System (INIS)

    Highlights: • The thermal performances and cost analysis of the double-pass solar collector with and without fins absorber were discussed. • The theoretical and experimental study on the double-pass solar air collector with and without fins absorber was conducted. • The ratio of AC/AEG or the cost benefit ratio was presented. • The double-pass solar collector with fins absorber is more cost-effective compared to without fins absorber. - Abstract: The performance and cost benefit analysis of double-pass solar collector with and without fins have been conducted. The theoretical model using steady state analysis has been developed and compared with the experimental results. The performance curves of the double-pass solar collector with and without fins, which included the effects of mass flow rate and solar intensity on the thermal efficiency of the solar collector, were obtained. Results indicated that the thermal efficiency is proportional to the solar intensity at a specific mass flow rate. The thermal efficiency increased by 9% at a solar intensity of 425–790 W/m2 and mass flow rate of 0.09 kg/s. The theoretical and experimental analysis showed a similar trend as well as close agreement. Moreover, a cost-effectiveness model has been developed examine the cost benefit ratio of double-pass solar collector with and without fins. Evaluation of the annual cost (AC) and the annual energy gain (AEG) of the collector were also performed. The results show that the double-pass solar collector with fins is more cost-effective compared to the double-pass solar collector without fins for mass flow rate of 0.01–0.07 kg/s. Also, simulations were obtained for the double-pass solar collector with fins at Nusselt number of 5.42–36.21. The energy efficiency of collector increases with the increase of Nusselt number. The results show that by increasing the Nusselt number simultaneously would drop the outlet temperature at any solar intensity. Increase in Nusselt number causes an increase in energy efficiency. On the other hand, the exergy efficiency has been obtained, which the fluctuation of exergy efficiency was based on the Nusselt number, collector length and solar intensity level

  8. Hydrodynamic Performance of an Undulatory Robot: Functional Roles of the Body and Caudal Fin Locomotion

    Directory of Open Access Journals (Sweden)

    Li Wen

    2013-01-01

    Full Text Available Both body undulation and caudal fin flapping play essential locomotive roles while a fish is swimming, but how these two affect the swimming performance and hydrodynamics of fish individually is yet to be known. We implemented a biomimetic robotic fish that travel along a servo towing system, which can be regarded as “treadmill” of the model. Hydrodynamics was studied as a function of the principal kinetic parameters of the undulatory body and caudal fin of the model in a self?propelled condition, under which the time?averaged measured axial net force becomes zero. Thrust efficiency was estimated from two?dimensional digital particle image velocimetry (DPIV measurements in the horizontal and mid?caudal fin plane. The Single?Row Reverse Karman wake (2S is commonly observed in many previous studies of live fish swimming. However, we show that a Double?Row Two?Paired vortices (2P wake was generated by the robotic model for most kinetic parameter combinations. Interestingly, the 2S wake emerged within the results of a narrow range of robotic caudal fin pitch angles (0???10°, occurring concurrently with enhanced thrust efficiency. We also show that, compared with the effect of body wavelength (?, the wake structure behind the robotic swimmer is more sensitive to the Strouhal number (St and caudal fin pitch angle (?.

  9. SEAKEEPING PERFORMANCE OF SEMI-SWATH IN FOLLOWING SEA USING CONTROLLED FINS STABILIZER

    OpenAIRE

    Rahimuddin

    2014-01-01

    Semi-SWATH ship design is a result of combining the good features of SWATH and Catamaran designs. However, the disadvantage of semi-SWATH is that she has low restoring force at bow that causes a tendency to bow-dive when running in following seas. In some critical conditions, the foredeck was found to be immersed underwater. One of the efforts to improve the ship???s performance is to install fin stabilizers at bow and stern. The fin stabilizers are used to compensate for the low restoring fo...

  10. MODERN MANUFACTURING TECHNIQUES OF PRECISED MISSILE REAR FIN ASSEMBLY

    Directory of Open Access Journals (Sweden)

    Md Akhtar khan

    2013-11-01

    Full Text Available Missile rear fin is mainly used for direction control. The fin includes number of components likepanels, pins, tubes, lamina and caps. The performance of actuation system plays a decisive role indetermining the performance of the flight control system for a highly maneuverable missile. To controlthe missiles by aerodynamics, control surfaces, sometimes called fins, are used. The manufacturingprocess of missile fin components involves different operations like CNC turning, CNC milling,drilling, EDM, grinding, and surface treatments. The paper presents the study of manufacturingprocesses of missile rear fin assembly.

  11. Verification of the performance of impact limiting fins for transportation containers

    International Nuclear Information System (INIS)

    Empirical data are frequently applied in designing the crush limiting fins for the special transport containers used for shipping radioactive materials. One of the most widely accepted sets of design curves was derived from research work done at Oak Ridge National Laboratories (ORNL) in 1971. This report presents the results of experimental work aimed at verifying particular aspects of the applicability of the ORNL design curves. The main objective was to check the fundamental assumption inherent in the ORNL data - namely that the design curve data can be extrapolated to any fin configuration regardless of the length and number of fins. Using a drop facility similar to ORNL, but with a modern computerized data capture system, data were collected from 625 specimens. These comprised both single and multiple fin types, that differed in height, thickness, length, angle of inclination and orientation. Included were several duplicate ORNL fin specimens for reference. Results obtained from the work reported here indicate that the basic premise regarding the extrapolation from the design curve data is reasonable. However, the results do not produce curves consistent with the ORNL curves. The newer curves of absorbed energy versus percent deformation are flatter, indicating that the percent deformation for a given energy input can sometimes vary considerably. For plots of the peak force per fin width versus height/thickness ratios the sharp upward trend for height/thickness ratios below 10 is not observed. The results obtained indicate that further work should be performed to determine the reason for the differences between the ORNL data and those data obtained from this project

  12. Experimental analysis on thermal performance of a solar air collector with longitudinal fins in a region of Biskra, Algeria

    Directory of Open Access Journals (Sweden)

    Foued Chabane

    2013-01-01

    Full Text Available This paper presents a thermal performance of a single pass solar air heater with fins attached was investigated experimentally. Longitudinal fins were used inferior the absorber plate for an increase the heat exchange and uniform the flow fluid in the channel. The effects of mass flow rate of air on the outlet temperature, the heat transfer in a thickness of solar collector and thermal efficiency were studied. Experiments were performed for two air mass flow rates of 0.012 kg/s., Moreover; the maximum efficiency was obtained by using five longitudinal fins and without fins. The maximum efficiency obtained for the 0.012 kg/s with and without fins were 40.02 % and 34.92 %, respectively. Comparison of the results as an effect the solar collector’s with and without fins shows a substantial enhancement in the thermal efficiency.

  13. Performance of multi tubes in tube helically coiled as a compact heat exchanger

    Science.gov (United States)

    Nada, S. A.; El Shaer, W. G.; Huzayyin, A. S.

    2014-12-01

    Multi tubes in tube helically coiled heat exchanger is proposed as a compact heat exchanger. Effects of heat exchanger geometric parameters and fluid flow parameters; namely number of inner tubes, annulus hydraulic diameter, Reynolds numbers and input heat flux, on performance of the heat exchanger are experimentally investigated. Different coils with different numbers of inner tubes, namely 1, 3, 4 and 5 tubes, were tested. Results showed that coils with 3 inner tubes have higher values of heat transfer coefficient and compactness parameter (bar{h} Ah ). Pressure drop increases with increasing both of Reynolds number and number of inner tubes. Correlations of average Nusselt number were deduced from experimental data in terms of Reynolds number, Prandtl number, Number of inner coils tubes and coil hydraulic diameter. Correlations prediction was compared with experimental data and the comparison was fair enough.

  14. Effect of the inertance tube on the performance of the Stirling type pulse tube refrigerator

    International Nuclear Information System (INIS)

    The Pulse Tube Refrigerator(PTR), which has no moving parts at its cold section, is attractive for obtaining higher reliability, simpler construction and lower vibration than in any other small cryocoolers. Commonly used mean to achieve optimum performance of the PTR are orifice or inertance tube. The Stirling type Pulse Tube Refrigerator in the experiments consists of a compressor driven by linear motors, which make pressure waves, a regenerator, a pulse tube with inertance tube, and a buffer. The pressures and temperature are measured to explore the dependency of inertance tube on the performance of the PTR. The results show the dependency of cool-down characteristics, no-load temperature on frequency of operation and inertance tube

  15. Experimental analysis on vortex tube energy separation performance

    Science.gov (United States)

    Hamdan, Mohammad O.; Alawar, Ahmed; Elnajjar, Emad; Siddique, Waseem

    2011-12-01

    The present study reports the effect of several operating parameters on the thermal performance of the vortex tube. The experimental results indicate that the inlet pressure and the cold fraction are the most significant parameters influencing the vortex tube performance. The experimental data point out that insulation has minimal effect on the vortex tube performance. The same inlet pressure tests show that energy separation increases as number of inlet nozzle increases.

  16. Steam generator tubing and associated operating performance

    International Nuclear Information System (INIS)

    Tubes for U-tube steam generators in power plants with pressurized water reactors are fabricated from Inconel 600, Incoloy 800 and, more recently, Inconel 690. The choice of tube materials is a crucial factor in ensuring trouble-free steam generator operation. The design and operating modes selected for steam generators and their associated water/steam cycles are equally important factors. Excellent operating results with good availability factors have been achieved by Siemens PWRs with steam generator tubing of Incoloy 800 and water/steam cycles operated in the high all-volatile treatment mode. Considerable corrosion problems are associated with the material Inconel 600. Long-term experience with Inconel 690 is not yet available. (orig.)

  17. Performance of a tapered pulse tube

    International Nuclear Information System (INIS)

    In a well instrumented pulse tube refrigerator having 1,500 W of cooling power at 125 K, the authors have measured the figure of merit of a tapered pulse tube at several operating points. At operating points near the operating point for which the taper was designed, the figure of merit is 0.96. This is close to the theoretical optimum figure of merit 0.97 calculated for this pulse tube considering only two loss mechanisms: heat conduction in the metal pulse tube wall and ordinary thermoacoustic heat transport in the gas within a few thermal penetration depths of the wall. At operating points farther from the design operating point, the measured figure of merit is much lower, as streaming driven convection adds a third loss mechanism

  18. Evaluation Performance ofan Annular Composite Fin by UsingMATLAB Programming

    Directory of Open Access Journals (Sweden)

    Padma Lochannayak

    2015-04-01

    Full Text Available The aim of this project is analysis the efficiency ratio in an annular fin by the variation of heat transfer coefficient for any surface condition by using MATLAB software to calculate the base fin efficiency and the coated fin efficiency by the variation of heat transfer coefficient, radius ratio and base fin thickness of an annular fin and compare the coating fin efficiency to base fin efficiency. If the heat transfer coefficient is 50W/m2K the increase efficiency ratio is 10.46 – 28.02% for zinc coating fin from the literature but the MATLAB result is 9.3 - 25.54% , the gain efficiency ratio at thicker base fin (d=0.001m is 11.72%, at the thinner base fin (d=0.0002m is 33.57% from the literature but the MATLAB result is 7.45% (d=0.001m and 32.14% (d=0.0002m for zinc coating fin and the gain efficiency ratio at thicker base fin (d=0.001m is 11.92%, at the thinner base fin (d=0.0002m is 33.61% from the literature but the MATLAB result is 7.51% (d=0.001m and 32.16% (d=0.0002m for zinc alloy coating fin.

  19. Thermal performance of plate-fin heat exchanger using passive techniques: vortex-generator and nanofluid

    Science.gov (United States)

    Khoshvaght-Aliabadi, Morteza

    2015-06-01

    This experimental study investigates the effects of vortex-generator (VG) and Cu/water nanofluid flow on performance of plate-fin heat exchangers. The Cu/water nanofluids are produced by using a one-step method, namely electro-exploded wire technique, with four nanoparticles weight fractions (i.e. 0.1, 0.2, 0.3, and 0.4 %). Required properties of nanofluids are systematically measured, and empirical correlations are developed. A highly precise test loop is fabricated to obtain accurate results of the heat transfer and pressure drop characteristics. Experiments are conducted for nanofluids flow inside the plain and VG channels. Based on the experimental results, utilizing the VG channel instead of the plain channel enhances the heat transfer rate, remarkably. Also, the results show that the VG channel is more effective than the nanofluid on the performance of plate-fin heat exchangers. It is observed that the combination of the two heat transfer enhancement techniques has a noticeably high thermal-hydraulic performance, about 1.67. Finally, correlations are developed to predict Nusselt number and friction factor of nanofluids flow inside the VG channel.

  20. Studying the performance of solid/perforated pin-fin heat sinks using entropy generation minimization

    Science.gov (United States)

    Elsayed, Mohamed L.; Mesalhy, Osama

    2015-05-01

    Heat transfer and pressure drop characteristics of a set of pin-fins with uniform heat flux were investigated experimentally and numerically. Test set-up was designed to assess the effects of mass flow rate, fin height, and fin density on convection heat transfer and pressure drop. In the numerical investigation, the flow field of various design parameters of the heat sink was simulated. It was found that heat sinks having fin heights of 20 and 30 mm operated at a lower Reynolds number reached minimum value for thermal resistance when the fin density 10 × 10. Which means it is the optimum number of fins for this case. Also, friction factor increased with a decrease in the bypass flow area or inter-fin distance spacing and using perforated fins reduced the pressure losses and thermal resistance for all studied cases.

  1. Steam condensation on finned tubes, in the presence of non-condensable gases and aerosols: Influence of impaction, diffusiophoresis and settling on aerosol deposition

    International Nuclear Information System (INIS)

    This paper presents a mechanistic model to predict the steam condensation on containment finned tube heat exchangers in the presence of non-condensable gases (NC) and aerosols. The total thermal resistance from the bulk gas to the coolant is formulated as a parallel combination of the convective and condensation gas resistances coupled in series to those of condensate layer, the aerosol fouling layer, the wall, and the coolant. The condensate layer thermal resistance is calculated by means of an Adamek-based condensation model. The aerosol fouling layer is computed based on diffusiophoresis, settling and impaction mechanisms. The gas mixture (steam plus NC) thermal resistance is formulated based on a diffusion layer modeling. Finally, this paper presents a Montecarlo method implemented in the FORTRAN code TAEROSOL that is able to compute the amount of aerosol mass that is deposited by impaction on the top of the finned tubes. The model results are compared with the available experimental data of the CONGA European project

  2. Thermal performance of circular convective–radiative porous fins with different section shapes and materials

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • LSM is an accurate technique for simulating heat transfer in circular porous fins. • Rectangular, convex, triangular and exponential variable sections are considered. • Radiation and convection from porous fin are considered. • Effects of material and geometry on heat transfer from fins are studied. - Abstract: In this study, heat transfer and temperature distribution equations for circular convective–radiative porous fins are presented. It’s assumed that the thickness of circular fins varies with radius so four different shapes, rectangular, convex, triangular and exponential, are considered. The heat transfer through porous media is simulated using passage velocity from the Darcy’s model. After deriving equation for each geometry, Least Square Method (LSM) and fourth order Runge–Kutta method (NUM) are applied for predicting the temperature distribution in the porous fins. The selected porous fin’s materials are Al, SiC, Cu and Si3N4. Results reveal that LSM has very effective and accurate in comparison with the numerical results. As a main outcome, Si3N4-exponential section fin has the maximum amount of transferred heat among other fins

  3. Numeric Simulation on the Performance of an Undulating Fin in the Wake of a Periodic Oscillating Plate

    Directory of Open Access Journals (Sweden)

    Zhang Yong-Hua

    2013-10-01

    Full Text Available A two-dimensional unsteady computational fluid dynamics (CFD method using an unstructured, grid-based and unsteady Navier-Stokes solver with automatic adaptive re-meshing to compute the unsteady flow was adopted to study the hydrodynamic interaction between a periodic oscillating plate and a rigid undulating fin in tandem arrangement. The user-defined function (UDF program was compiled to define the undulating and oscillating motion. First, the influence of the distance between the anterior oscillating plate and the posterior undulating fin on the non-dimensional drag coefficient of the fin was investigated. Ten different distances, D=0.2L, 0.4L, 0.6L, 0.8L, 1.0L, 1.2L, 1.4L, 1.6L, 1.8L and 2.0L, were considered. The performance of the fin for different distances (D is different. Second, the plate oscillating angle (5.7o, 10 o, 20 o, 30 o, 40 o, 45 o, 50 o and frequency (0.5 Hz, 1.0 Hz, 1.5 Hz, 2.0 Hz, 2.5 Hz, 3.0 Hz, 3.5 Hz, 4.0 Hz effects on the non-dimensional drag coefficient of the fin were also implemented. The pressure distribution on the fin was computed and integrated to provide fin forces, which were decomposed into lift and thrust. Meanwhile, the flow field was demonstrated and analysed. Based on the flow structures, the reasons for different undulating performances were discussed. It shows that the results largely depend on the distance between the two objects. The plate oscillating angle and frequency also make a certain contribution to the performance of the posterior undulating fin. The results are similar to the interaction between two undulating objects in tandem arrangement and they may provide a physical insight into the understanding of fin interaction in fishes or bio-robotic underwater propulsors that are propelled by multi fins.

  4. Performance Investigation of a two Reflector Box Type Solar Cooker with a Finned Absorber Plate : A Review

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar*1,

    2014-04-01

    Full Text Available This review paper presents the work of various researchers on the performance of solar cooker. In this research author used finned absorber plate inside bottom surface of solar cooker and The top cover (Glazing is tilted at 23.16° corresponding to the latitude of jabalpur (the location of the test site. To provide the tilt, the height of the back side will made 25.47 cm while it will made 10 cm for the front one. Four caster wheels have been provided under the cooker This review paper presents, the work of various researchers on the performance of solar to change orientation of the cooker towards the sun. According to given above specification, A two reflector box type solar cooker with a finned absorber plate will be fabricated and performance compared with a box type solar cooker without reflector mirror and finned absorber plate.

  5. Evaluation of the thermodynamic performance of pulse tubes

    International Nuclear Information System (INIS)

    The thermodynamic performance of pulse tubes (PT) has been studied with emphasis on second law efficiencies and volume effects. The various pulse tube data of operation are compared to small Stirling coolers, characterized by a parameter set similar to the PT specifications. A modified open-quotes thermal shuntclose quotes model (modified open-quotes Bejan modelclose quotes) is utilized for the comparison. The model predicts a small refrigeration load asymptote of the efficiency proportional to the load itself in partial agreement with pulse tube data

  6. Finned heat exchangers. Ia. General and basic aspects

    International Nuclear Information System (INIS)

    This paper is a review of the main literature studies about the finned heat exchanger modelling and simulation. Finned heat exchangers are used in cryogenic industry, nuclear industry, food industry, medicine, etc. The aspects concerning the air circulation through the heat exchanger component tubes are studied, as well as those involved in the thermal transfer from technological fluid to wall or from fin to air. A particular attention is devoted to the physical and mathematical complete models of finned heat exchangers, as well as to the criterial relationship for the calculation of the partial thermal transfer to air, ?2, fin efficiency, ?a and friction coefficient, f. Details are also given about the influence of the thermal contact resistance on the finned heat exchanger performance. This study is a useful tool for a correct technological sizing of this heat exchanger type. (authors)

  7. Finned heat exchanger. Ib. General and basic aspects

    International Nuclear Information System (INIS)

    This paper is a review of the main literature studies about the finned heat exchanger modelling and simulation. Finned heat exchangers are used in cryogenic industry, nuclear industry, food industry, medicine, etc.. The aspects concerning the air circulation through the heat exchanger component tubes are studied, as well as those involved in the thermal transfer from technological fluid to wall or from fin to air. A particular attention is devoted to the physical and mathematical complete models of finned heat exchangers, as well as to the criterial relationship for the calculation of the partial heat transfer to air (?2), fin efficiency (?a) and friction coefficient (f). Details are also given about the influence of the thermal contact resistance on the finned heat exchanger performance. This study is a useful tool for a correct technological sizing of this type of heat exchangers. (authors)

  8. Numerical simulation of the thermal hydraulic performance of a plate pin fin heat sink

    International Nuclear Information System (INIS)

    The computational fluid dynamic software FLUENT is used in assessing the electronics cooling potential of a plate pin fin heat sink (PPFHS), including the conjugate effect. The simulation results are validated with reported experimental data. The simulation shows that pin height and air velocity have significant influences on the thermal hydraulic performances of PPFHS while the influences of in-line/staggered array and neighbor pin flow-directional center distance (NPFDCD) of the PPFHS are less notable. In applying the present design to the cooling of a desktop PC CPU at a heat flux of 2.20 W/cm2, the temperature can be kept at less than 358 K with an air velocity over 6.5 m/s. - Highlights: ? Pin height and air velocity significantly influence thermal performance of PPFHS. ? Less influence by in-line or staggered array. ? Less influence by neighbor pin flow-directional center distance. ? Design with >6.5 m/s air can cool to 2 flux.

  9. Performance characterization of the TRW 35K pulse tube cooler

    International Nuclear Information System (INIS)

    The TRW 35K pulse tube cooler is configured as an integral cooler, with the pulse tube attached perpendicular to a pair of compressors operating into a common compression chamber. The cooler was optimized for 35K operation and has a nominal cooling capacity of 850 mW at 35 K with a cooler input power of 200 W. It also provides 2 W of cooling at 60 K for 90 W of input power. The cooler was extensively characterized by JPL, measuring the thermal performance and the cooler-generated vibration and EMI as a function of piston stroke and offset position. The thermal performance was found to be quite sensitive to the piston offset position. The pulse tube parasitic conduction levels were also measured and shown to have a strong angular dependence relative to gravity. Magnetic shielding studies were performed to examine radiated magnetic emission levels from compressors with and without shielding

  10. Process for welding fins on metal parts and metal parts provided with fins by this process

    International Nuclear Information System (INIS)

    Process for welding components such as fins on to parts like tubes which avoids the formation of a copper deposit on the tube that would encourage corrosion. Cuts are made through part of the width of a strip. This strip is folded along its length and then wrapped around the part to be fitted with fins. The uncut part of the strip is made to bear on the periphery of the part to form the foot of the fin so that the cut part fans open forming segmented fins. A wheel is pressed on to the foot of a fin and another wheel is likewise pressed on to the foot of another fin in contact with the tube to close the electric circuit to the generator, the wheels and the tube being actuated rotationally in relation to each other so that the heat, generated in each successive contact between the fin to be welded and tube, welds the fin to the tube

  11. Thermal and friction drop characteristic of heat exchangers with elliptical tubes and smooth fins / Caracterización térmica e hidráulica de intercambiadores de calor con tubos elípticos y aletas lisas

    Scientific Electronic Library Online (English)

    Rubén, Borrajo-Pérez; Jurandir, Ititzo Yanagihara; Juan José, González-Bayón.

    2012-12-01

    Full Text Available Caída de presión y transferencia de calor son importantes parámetros en intercambiadores de calor. Existe falta de información cuando de intercambiadores de calor y tubos elípticos se trata. El objetivo del trabajo fue caracterizar experimentalmente modelos de intercambiadores de calor con tubos elí [...] pticos y aletas lisas. El numero de Reynolds y los espaciamientos fueron variados, dentro del régimen laminar. Los experimentos fueron desarrollados en un túnel de viento de circuito abierto usando la sublimación de naftaleno y la analogía calor y masa. Los números de Nusselt medio, locales y el factor de fricción fueron obtenidos en forma de correlaciones de Factores de Fricción y Colburn. Las correlaciones, validas para 200 Abstract in english Pressure drop and heat transfer are the most important parameters in compact heat exchanger. There is a lack of information in the literature about heat exchanger with elliptical tube. The objective of this work was the experimental characterization of compact heat exchangers models using elliptical [...] tube with eccentricity of 0,5 and smooth fins. The Reynolds numbers and the spacing were varied and always inside laminar regime. The experiments were conducted in an open wind tunnel using sublimation of naphthalene and the heat and mass transfer analogy. As results, the average and local Nusselt number and friction factor for 36 models were obtained. Correlations for Colburn and friction factors were presented. This correlations were obtained for 200

  12. Heat exchanger performance calculations for enhanced-tube condenser applications

    Energy Technology Data Exchange (ETDEWEB)

    Rabas, T.J.

    1992-01-01

    The lack of a prediction method is sometimes used for the rejection of enhanced tubes for some condenser applications even though there is ample data from single-tube condensing experiments. Three methods are discussed that can be used to rate and/or size these multitube units based on the single-tube experimental results. The Kern vertical-number correction appears to be quite adequate for most operating conditions, the exceptions being large sizes and/or deep vacuum operation. The bundle-factor method is preferred for these applications; however, field test results are required to obtain this factor. If performance data are not available, pointwise or numerical methods are required but special care must be taken to insure that the adverse effects of noncondensable gas pockets and the saturation-temperature depression are properly addressed.

  13. Heat exchanger performance calculations for enhanced-tube condenser applications

    Energy Technology Data Exchange (ETDEWEB)

    Rabas, T.J.

    1992-07-01

    The lack of a prediction method is sometimes used for the rejection of enhanced tubes for some condenser applications even though there is ample data from single-tube condensing experiments. Three methods are discussed that can be used to rate and/or size these multitube units based on the single-tube experimental results. The Kern vertical-number correction appears to be quite adequate for most operating conditions, the exceptions being large sizes and/or deep vacuum operation. The bundle-factor method is preferred for these applications; however, field test results are required to obtain this factor. If performance data are not available, pointwise or numerical methods are required but special care must be taken to insure that the adverse effects of noncondensable gas pockets and the saturation-temperature depression are properly addressed.

  14. Performance analysis and optimization of high capacity pulse tube refrigerator

    Science.gov (United States)

    Ghahremani, Amir R.; Saidi, M. H.; Jahanbakhshi, R.; Roshanghalb, F.

    High capacity pulse tube refrigerator (HCPTR) is a new generation of cryocoolers tailored to provide more than 250 W of cooling power at cryogenic temperatures. The most important characteristics of HCPTR when compared to other types of pulse tube refrigerators are a powerful pressure wave generator, and an accurate design. In this paper the influence of geometrical and operating parameters on the performance of a double inlet pulse tube refrigerator (DIPTR) is studied. The model is validated with the existing experimental data. As a result of this optimization, a new configuration of HCPTR is proposed. This configuration provides 335 W at 80 K cold end temperature with a frequency of 50 Hz and COP of 0.05.

  15. Effects of regenerator geometry on pulse tube refrigerator performance

    Science.gov (United States)

    Lewis, M.; Kuriyama, T.; Xiao, J. H.; Radebaugh, R.

    1998-01-01

    This paper gives results of the cooling performance of a double-inlet pulse tube refrigerator using various regenerators. The same pulse tube was used for all the experiments and measured 4.76 mm in diameter and 46.2 mm in length. A commercial linear compressor with a swept volume of 4 cm3 was used in these experiments. The operating conditions were held constant at a mean pressure of 2.0 MPa and a frequency of 54 Hz. Using finite difference software called REGEN3.1, developed at NIST, and recent experiment results, we optimized a series of regenerators based on dimensions, materials and screen packing. The values used for calculating the thermal conduction through stacked screens by REGEN3.1 were based on recent experimental results from NIST. The regenerator tubes were designed using 316 stainless steel and titanium materials. The regenerator matrices investigated were 400-mesh and 500-mesh stainless steel screen. The valve settings for both orifices were adjusted to minimize the no-load temperature for all regenerators. A cooling capacity curve from 0 to 3 W was also determined. The performance of the pulse tube refrigerator using the different regenerators is discussed. The experimental results from the various regenerators are evaluated and compared with their corresponding numerically calculated coefficient of performance (COP) and regenerator design as determined by REGEN3.1.

  16. A Comparative Study of Conventional and Tip-Fin Propeller Performance

    DEFF Research Database (Denmark)

    Andersen, Poul

    1997-01-01

    During more than a decade several attempts have been made to obtain higher propeller efficiencies by radically modifying the geometry in the tip region of the blade. In the tip-fin propeller a tip fin or winglet is attached to the blade tip and integrated into the blade in such a way that the blade tip is softly curved towards the suction side.Whereas the developments previously have been concentrated mainly on increasing the efficiency of the propeller, the emphasis of current efforts has been on both high efficiency as well as good cavitation properties. This has resulted in a design with a combination of skew and tip fin. To evaluate the design, open-water, self-propulsion and cavitation model tests have been carried out. The tests are done for the conventional propeller originally designed for the ship and for a tip-fin propeller designed for the same ship under the same operation conditions.The results of the model tests show higher open-water efficiency of the tip-fin propeller as well as higher over-all propulsive efficency. Depending on the method used in the full-scale extrapolation this corresponds to reduction in propulsive power of 3.7 to 4.7 per cent. Both propellers suffer from slight wake field behind the ship. The tip-fin propeller suffered a little more from cavitation than the conventional propeller which gave rise to maximum, measured, first-order pressure pulses of 1.3 to 1.4 times those of the conventional propeller.

  17. Predicting optimum vortex tube performance using a simplified CFD model

    International Nuclear Information System (INIS)

    The Ranque-Hilsch tube is a particular type of vortex tube device. The flow enters the device tangentially near one end and exits from the open ends of the tube. The inlet air is of a uniform temperature throughout while the outputs are of different temperatures. One outlet is hotter and the other is colder than the inlet air. This device has no moving parts and does not require any additional power for its operation other than that supplied to the device to compress the inlet air. It has, however, not been widely used, mainly because of its low efficiency. In this paper, a simplified 2-dimensional computational fluid dynamics model for the flow in the vortex tube is developed using FLUENT. This model makes use of the assumption of axial symmetry throughout the entire flow domain. Compared to a three-dimensional computational solution, the simplified model requires significantly less computational time. This is important because the model is to be used for an optimization study. A user-defined function is generated to implement a modified version of the k-epsilon model to account for turbulence. This model is validated by comparing a particular solution with available experimental data. The variation of cold temperature drop and efficiency of the device with orifice diameter, inlet pressure and cold mass flow ratio qualitatively agree with experimental results. Variation of these performance indices with tube length did not agree with the experiments for small values ree with the experiments for small values of tube length. However, it did agree qualitatively for large values. (author)

  18. Predicting optimum vortex tube performance using a simplified CFD model

    Energy Technology Data Exchange (ETDEWEB)

    Karimi-Esfahani, M; Fartaj, A.; Rankin, G.W. [Univ. of Windsor, Dept. of Mechanical, Automotive and Materials Engineering, Windsor, Ontario (Canada)]. E-mail: mki_60@hotmail.com

    2004-07-01

    The Ranque-Hilsch tube is a particular type of vortex tube device. The flow enters the device tangentially near one end and exits from the open ends of the tube. The inlet air is of a uniform temperature throughout while the outputs are of different temperatures. One outlet is hotter and the other is colder than the inlet air. This device has no moving parts and does not require any additional power for its operation other than that supplied to the device to compress the inlet air. It has, however, not been widely used, mainly because of its low efficiency. In this paper, a simplified 2-dimensional computational fluid dynamics model for the flow in the vortex tube is developed using FLUENT. This model makes use of the assumption of axial symmetry throughout the entire flow domain. Compared to a three-dimensional computational solution, the simplified model requires significantly less computational time. This is important because the model is to be used for an optimization study. A user-defined function is generated to implement a modified version of the k-epsilon model to account for turbulence. This model is validated by comparing a particular solution with available experimental data. The variation of cold temperature drop and efficiency of the device with orifice diameter, inlet pressure and cold mass flow ratio qualitatively agree with experimental results. Variation of these performance indices with tube length did not agree with the experiments for small values of tube length. However, it did agree qualitatively for large values. (author)

  19. Complicações em lipoaspiração clássica para fins estéticos Complications of classical liposuction performed for cosmetic purposes

    Directory of Open Access Journals (Sweden)

    Fernando Fabrício Franco

    2012-03-01

    Full Text Available A lipoaspiração realizada para procedimentos estéticos tem como objetivo a retirada de gordura em pacientes saudáveis e redução do acúmulo de gordura localizada, a chamada lipodistrofia, levando à melhora no contorno corporal. Nas últimas três décadas, a lipoaspiração vem sendo aperfeiçoada; porém, como qualquer outro procedimento cirúrgico, não é isenta de complicações. O objetivo deste estudo é realizar revisão da bibliografia, por meio do PubMed, identificando as complicações após lipoaspiração clássica, incluindo apenas aquelas realizadas com finalidade estética. Foram encontrados 210 artigos empregando a expressão "complication in liposuction", 86 artigos com "complication after liposuction", 27 artigos com "fat embolism after liposuction", 7 artigos com "fat embolism following liposuction" e 16 artigos com "deaths related to liposuction". Dentre esses artigos, apenas 84 foram considerados relacionados ao assunto, sendo encontrados casos de embolia gordurosa após lipoaspiração, perfuração visceral, lesão vascular, cegueira e infecção por herpes zoster, entre outros relatos. Com base nos artigos analisados foi possível concluir que a lipoaspiração é um procedimento altamente eficaz quando bem indicado e bem realizado, porém existem riscos inerentes ao ato cirúrgico. Este levantamento constatou que existem muitos artigos abordando complicações após lipoaspiração para fins estéticos, e a embolia gordurosa pulmonar apresenta alta incidência.Liposuction for esthetic purposes aims to remove fat in healthy patients and reduce localized fat accumulation, called lipodystrophy, in order to improve body contour. In the last 3 decades, the liposuction technique has improved dramatically. However, like any other surgical procedure, it is not without complications. Here, we reviewed the literature on PubMed to identify complications after classic liposuction performed solely for esthetic purposes. In total, 210 articles were found using the term "complication in liposuction," 86 with "complication after liposuction," 27 with "fat embolism after liposuction," 7 with "fat embolism following liposuction," and 16 with "deaths related to liposuction." Among these articles, only 84 including cases of fat embolism after liposuction, visceral perforation, vascular injury, blindness, and herpes zoster infection among others were considered to be related to the subject. Based on the analyzed articles, we can conclude that liposuction is a highly effective procedure when well indicated and performed accurately. Despite this, there are inherent risks. This review found many articles addressing complications, predominantly pulmonary fat embolism, after liposuction for esthetic purposes.

  20. Complicações em lipoaspiração clássica para fins estéticos / Complications of classical liposuction performed for cosmetic purposes

    Scientific Electronic Library Online (English)

    Fernando Fabrício, Franco; Rafael de Campos Ferreira, Basso; Alfio José, Tincani; Paulo, Kharmandayan.

    2012-03-01

    Full Text Available A lipoaspiração realizada para procedimentos estéticos tem como objetivo a retirada de gordura em pacientes saudáveis e redução do acúmulo de gordura localizada, a chamada lipodistrofia, levando à melhora no contorno corporal. Nas últimas três décadas, a lipoaspiração vem sendo aperfeiçoada; porém, [...] como qualquer outro procedimento cirúrgico, não é isenta de complicações. O objetivo deste estudo é realizar revisão da bibliografia, por meio do PubMed, identificando as complicações após lipoaspiração clássica, incluindo apenas aquelas realizadas com finalidade estética. Foram encontrados 210 artigos empregando a expressão "complication in liposuction", 86 artigos com "complication after liposuction", 27 artigos com "fat embolism after liposuction", 7 artigos com "fat embolism following liposuction" e 16 artigos com "deaths related to liposuction". Dentre esses artigos, apenas 84 foram considerados relacionados ao assunto, sendo encontrados casos de embolia gordurosa após lipoaspiração, perfuração visceral, lesão vascular, cegueira e infecção por herpes zoster, entre outros relatos. Com base nos artigos analisados foi possível concluir que a lipoaspiração é um procedimento altamente eficaz quando bem indicado e bem realizado, porém existem riscos inerentes ao ato cirúrgico. Este levantamento constatou que existem muitos artigos abordando complicações após lipoaspiração para fins estéticos, e a embolia gordurosa pulmonar apresenta alta incidência. Abstract in english Liposuction for esthetic purposes aims to remove fat in healthy patients and reduce localized fat accumulation, called lipodystrophy, in order to improve body contour. In the last 3 decades, the liposuction technique has improved dramatically. However, like any other surgical procedure, it is not wi [...] thout complications. Here, we reviewed the literature on PubMed to identify complications after classic liposuction performed solely for esthetic purposes. In total, 210 articles were found using the term "complication in liposuction," 86 with "complication after liposuction," 27 with "fat embolism after liposuction," 7 with "fat embolism following liposuction," and 16 with "deaths related to liposuction." Among these articles, only 84 including cases of fat embolism after liposuction, visceral perforation, vascular injury, blindness, and herpes zoster infection among others were considered to be related to the subject. Based on the analyzed articles, we can conclude that liposuction is a highly effective procedure when well indicated and performed accurately. Despite this, there are inherent risks. This review found many articles addressing complications, predominantly pulmonary fat embolism, after liposuction for esthetic purposes.

  1. Performance tests of Mn-added aluminum heat pipe with micro-sized inner fins and thermal fluid for cooling electronic device

    Science.gov (United States)

    Kim, M. R.; Choi, Y.

    2014-12-01

    Aluminum-5 wt % manganese alloy heat pipe with a nano-fluid of n-butanol and 0.2 wt % carbon nano-tubes was prepared by deep-drawing, and its mechanical and corrosion properties were determined to improve thermal conductivity performance. The heat pipe was designed to have micro-sized inner fins working at temperature higher than 200°C and simultaneously retaining a similar thermal conductivity to that of pure aluminum. The heat pipe formed by aluminum-5 wt % manganese alloys had improved mechanical properties such as 38% micro-hardness, 45.8% yield strength, and 53.5 wt % ultimate tensile strength due to grain size refinement and work hardening effects. The corrosion rate of the aluminum alloy in artificial sea water at room temperature decreased from 0.110 mpy to 0.102 mpy. The nano-fluid of n-butanol and 0.2 wt % carbon nano-tubes improved the thermal conductivity of the heat-pipe by about 250%.

  2. Performance of the CMS Drift Tube Chambers with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G

    2010-01-01

    Studies of the performance of the CMS drift tube barrel muon system are described, with results based on data collected during the CMS Cosmic Run at Four Tesla. For most of these data, the solenoidal magnet was operated with a central field of 3.8 T. The analysis of data from 246 out of a total of 250 chambers indicates a very good muon reconstruction capability, with a coordinate resolution for a single hit of about 260 microns, and a nearly 100% efficiency for the drift tube cells. The resolution of the track direction measured in the bending plane is about 1.8 mrad, and the efficiency to reconstruct a segment in a single chamber is higher than 99%. The CMS simulation of cosmic rays reproduces well the performance of the barrel muon detector.

  3. Nozzle parameters affecting vortex tube energy separation performance

    Science.gov (United States)

    Hamdan, Mohammad O.; Alsayyed, Basel; Elnajjar, Emad

    2013-04-01

    This experimental study reports the effect of nozzle parameters on the energy separation of the vortex tube. The results indicate that maximum energy separation is achieved with tangential nozzle orientation while the symmetry/asymmetry of nozzles has a minimal effect on the performance of the energy separation. For current selected conditions and parameters, the study shows that the optimum number of nozzles for maximum energy separation is around 4 nozzles.

  4. Numerical analysis on performance of naphthalene phase change thermal storage system in aluminum plate-fin unit

    Science.gov (United States)

    Yang, Lin; Peng, Hao; Ling, Xiang; Dong, Huihua

    2015-02-01

    This paper presents a numerical simulation for the prediction of time, temperature and liquid fraction during the melting and solidification process in the latent heat storage of phase changed materials (PCM). The mathematical model, regarding the solid-liquid phase change heat transfer based on the enthalpy formulation, has been proposed. Naphthalene was used as the PCM which is contained in up layer of plate-fin thermal storage. Transient simulations were performed using a commercial computational fluid dynamics package, Fluent, based on the finite volume method. This computational model endeavored to describe both the melting and solidification processes of the PCM. A series of numerical calculations have been done in order to analyses the influence of several heat transfer fluid operating conditions and several fin geometric parameters on the thermal storage unit. Numerical results, which could be used for operating conditions and geometry optimization, provide guideline for the design of the latent thermal energy storage system.

  5. COMPARISON OF TEMPORAL PARAMETERS OF SWIMMING RESCUE ELEMENTS WHEN PERFORMED USING DOLPHIN AND FLUTTER KICK WITH FINS - DIDACTICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Marek Rejman

    2012-12-01

    Full Text Available The aim of this study was an analysis of the time required to swim to a victim and tow them back to shore, while perfoming the flutter-kick and the dolphin-kick using fins. It has been hypothesized that using fins while using the dolphin-kick when swimming leads to reduced rescue time. Sixteen lifeguards took part in the study. The main tasks performed by them, were to approach and tow (double armpit a dummy a distance of 50m while applying either the flutter-kick, or the dolphin-kick with fins. The analysis of the temporal parameters of both techniques of kicking demonstrates that, during the approach to the victim, neither the dolphin (tmean = 32.9s or the flutter kick (tmean = 33.0s were significantly faster than the other. However, when used for towing a victim the flutter kick (tmean = 47.1s was significantly faster when compared to the dolphin-kick (tmean = 52.8s. An assessment of the level of technical skills in competitive swimming, and in approaching and towing the victim, were also conducted. Towing time was significantly correlated with the parameter that linked the temporal and technical dimensions of towing and swimming (difference between flutter kick towing time and dolphin-kick towing time, 100m medley time and the four swimming strokes evaluation. No similar interdependency has been discovered in flutter kick towing time. These findings suggest that the dolphin-kick is a more difficult skill to perform when towing the victim than the flutter-kick. Since the hypothesis stated was not confirmed, postulates were formulated on how to improve dolphin-kick technique with fins, in order to reduce swimming rescue time

  6. Modeling the discontinuous individual channel injection into fin-and-tube evaporators for residential air-conditioning

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2012-01-01

    In this paper a working principle based upon the novel expansion and distributor device EcoFlowTM is analyzed. The device enables compensation of flow maldistribution by control of individual channel superheat. The working principle is discontinuous liquid injection (pulsating flow) into each individual channels during a specified cycle time. Moreover, the influence of the injection cycle time is investigated together with an optional secondary flow into the other channels with regards to cooling capacity, overall UA-value and COP. The results showed spurious fluctuations in pressure when simulating the pulsating flow, thus the dynamic behavior in the mixture two-phase flow model is insufficient to model the discontinuous liquid injection principle. Despite, the fluctuations and imperfections of the model we found that the cycle time should be kept as low as possible and that the optional secondary flow increases performance. Moreover, the paper reports on the applicability of Modelica developed models to analyze and optimize the working principle and design of expansion devices such that Modelica may be used in future development of novel discontinuous expansion devices.

  7. Development and performance of a double diaphragm shock tube

    International Nuclear Information System (INIS)

    After recalling the techniques used to produce intense shocks in gases, the double diaphragm shock tube (T.C.D.2), studied and developed at the Vaujours Research Center, is presented. The theoretical and experimental performances were compared, argon being used as the test gas. In this way, it was shown that shock waves having velocities as high as 15 km/s could be produced. Various diagnostic techniques were employed to measure the velocity of the wave front and its attenuation, as well as the thickness of the gas heated by the shock (expressed generally by the test time, ?, at a given point). An estimation of the temperature and electron number density of the plasma behind the shock was effected spectroscopically. The experimental results obtained confirm theoretical predictions. It is shown that the velocity gain of T.C.D.2 over a simple shock tube may be as high as 60 per cent. (author)

  8. Experimental investigation of the effects of orientation angle on heat transfer performance of pin-finned surfaces in natural convection

    International Nuclear Information System (INIS)

    Natural convection heat transfer in air from a pin-finned surface is investigated experimentally by considering the effect of radiation heat transfer. The plate was oriented as the pin arrays facing either downwards or upwards from vertical axis with different angles and the experiments were performed for different values of heater power input. From the results of the experiments it is observed that the pin fins increase the heat transfer considerably when compared to the unpinned surface. The upfacing pins are more enhancing heat transfer than the downfacing pins and the enhancement is decreasing with increasing orientation angle from the vertical axis. -- Research highlights: ? Effect of orientation in free convection heat transfer from a pin-finned surface. ? The upfacing pins are more enhancing heat transfer than the downfacing pins. ? Radiation view factor is calculated by a modular analysis. ? The radiation is comparable to free convection as not to be neglected. ? The radiative part is 25-40% and increases for low heat transfer rates.

  9. Performance of 2mm radius straw tube drift cells

    International Nuclear Information System (INIS)

    The performance of a 128 channel test module made with straw tubes of 2mm radius has been studied in a test beam and with cosmic rays. Different gases were used and for each one the time-to-distance relation and the hit efficiency was measured. Comparison are made between results when two different electronics readouts were used. The information was recorded with 106 MHz FADC units and also with TDCs (50ps resolution). The best resolution, of 135 ?m, was obtained using 50% ethane, 50% argon and reading out the information with the TDCs, at an operating HV of 1,750V

  10. Commissioning, Operation and Performance of the CMS Drift Tube Chambers

    CERN Document Server

    Cerminara, Gianluca

    2010-01-01

    The CMS muon spectrometer, designed to trigger, identify, reconstruct and measure muons with high efficiency and accuracy, is equipped with Drift Tube chambers (DT) in the barrel region. The DT system has been fully commissioned using cosmic muons with and without magnetic field, and during months of cosmic data taking has provided millions of triggers to the rest of the CMS detector. This contribution will describe the challenges in the operation of the DT system, including calibration procedures, monitoring and reconstruction performance, and the result of the analysis of the collected cosmic data.

  11. Thermal Performance of Convective-Radiative Heat Transfer in Porous Fins

    Directory of Open Access Journals (Sweden)

    Majid SHAHBABAEI

    2014-01-01

    Full Text Available Forced and natural convection in porous fins with convective coefficient at the tips under radiation and convection effects are investigated in this paper. Aluminum and copper as fin materials are investigated. In forced and natural convection, air and water are applied as working fluids, respectively. In order to solve this nonlinear equation, Homotopy Perturbation Method (HPM and Variational Iteration Method (VIM are used. To verify the accuracy of the methods, a comparison is made to the exact solution (BVP. In this work, the effects of porosity parameter (, Radiation parameter (? and Temperature-Ratio parameter (µ on non-dimensional temperature distribution for both of the flows are shown. The results show that the effects of (? and (µ on temperature distribution in natural convection are based on porosity and in forced convection are uniform, approximately. Also, it is shown that both VIM and HPM are capable of being used to solve this nonlinear heat transfer equation.doi:10.14456/WJST.2014.64

  12. Performance Investigation of a two Reflector Box Type Solar Cooker with a Finned Absorber Plate : A Review

    OpenAIRE

    Pradeep Kumar*1,; Dr. B. K. Chourasia2

    2014-01-01

    This review paper presents the work of various researchers on the performance of solar cooker. In this research author used finned absorber plate inside bottom surface of solar cooker and The top cover (Glazing) is tilted at 23.16° corresponding to the latitude of jabalpur (the location of the test site). To provide the tilt, the height of the back side will made 25.47 cm while it will made 10 cm for the front one. Four caster wheels have been provided under the cooker This re...

  13. Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance in the Trinidadian guppy (Poecilia reticulata)

    DEFF Research Database (Denmark)

    Svendsen, Jon Christian; Banet, Amanda I.

    2013-01-01

    There is considerable intraspecific variation in metabolic rates and locomotor performance in aquatic ectothermic vertebrates; however, the mechanistic basis remains poorly understood. Using pregnant Trinidadian guppies (Poecilia reticulata), a livebearing teleost, we examined the effects of reproductive traits, pectoral fin use and burse-assisted swimming on swimming metabolic rate, standard metabolic rate (MO2std) and prolonged swimming performance (Ucrit). Reproductive traits included reproductive allocation and pregnancy stage, the former defined as the mass of the reproductive tissues divided by the total body mass. Results showed that the metabolic rate increased curvilinearly with swimming speed. The slope of the relationship was used as an index of swimming cost. There was no evidence that reproductive traits correlated with swimming cost, MO2std or Ucrit. In contrast, data revealed strong effects of pectoral fin use on swimming cost and Ucrit. Poecilia reticulata employed body-caudal fin (BCF) swimming at all tested swimming speeds; however, fish with a high simultaneous use of the pectoral fins exhibited increased swimming cost and decreased Ucrit. These data indicated that combining BCF swimming and pectoral fin movement over a wide speed range, presumably to support swimming stability and control, is an inefficient swimming behaviour. Finally, transition to burst-assisted swimming was associated with an increase in aerobic metabolic rate. Our study highlights factors other than swimming speed that affect swimming cost and suggests that intraspecific diversity in biomechanical performance, such as pectoral fin use, is an important source of variation in both locomotor cost and maximal performance.

  14. Fluid-structure interaction numerical simulation of thermal performance and mechanical property on plate-fins heat exchanger

    Science.gov (United States)

    Zhang, Lingie; Qian, Zuoqin; Deng, Jun; Yin, Yuting

    2015-02-01

    A numerical simulation and experimental study of heat transfer, fluid flow and fins mechanical property on plate-fin heat exchanger has been presented in this paper. The methods used in this study are experiment, CFD analysis, fluid-structure interaction and finite element method. An air-oil wind tunnel is established for this experiment. The temperature difference, pressure drop, streamlines are obtained in overall model, and the heat transfer coefficient, j/f factor, temperature and stress distribution of plate-fin body are obtained in different fin thickness and fin offset. The prediction from the CFD simulation shows reasonably good agreement with the experimental results.

  15. High-Rate Performance of Muon Drift Tube Detectors

    CERN Document Server

    Schwegler, Philipp

    The Large Hadron Collider (LHC) at the European Centre for Particle Physics, CERN, collides protons with an unprecedentedly high centre-of-mass energy and luminosity. The collision products are recorded and analysed by four big experiments, one of which is the ATLAS detector. In parallel with the first LHC run from 2009 to 2012, which culminated in the discovery of the last missing particle of the Standard Model of particle physics, the Higgs boson, planning of upgrades of the LHC for higher instantaneous luminosities (HL-LHC) is already progressing. The high instantaneous luminosity of the LHC puts high demands on the detectors with respect to radiation hardness and rate capability which are further increased with the luminosity upgrade. In this thesis, the limitations of the Muon Drift Tube (MDT) chambers of the ATLAS Muon Spectrometer at the high background counting rates at the LHC and performance of new small diameter muon drift tube (sMDT) detectors at the even higher background rates at HL-LHC are stud...

  16. Experimental analysis on frosting characteristic of SK-type finned refrigerating heat exchanger with large-diameter circular holes

    International Nuclear Information System (INIS)

    This paper presents the construction of both a plane fin-and-tube heat exchanger and a SK-type fin-and-tube heat exchanger. Based on plane fin-and-tube heat exchanger, comparative industrial prototype experiments of SK-type fin-and-tube heat exchanger energy efficiency performance were carried out in the artificial climate chamber. Test results confirmed several findings: when the amount of the refrigerant charged is the same and face velocity u = 3.75 m s?1, SK-type fin-and-tube heat exchanger refrigeration capacity increases by an average of 9.13%; energy consumption reduces by an average of 11.25%, coefficient of performance (COP) of heat exchanger increases by an average of 22.65% with continuous operation during the first 2 h. Also, when the operation time exceeds 2 h, the COP of both types of heat exchangers are both less than 0.6, illustrating that under frost conditions, the defrost interval should not be too long, otherwise energy consumption may sharply spike. - Highlights: •The large holes of SK-type induced the generation of turbulence flow. •The refrigeration capacity and COP of SK-type exceeds that of plane one. •The SK-type fin-and-tube heat exchanger is a new kind of heat transfer equipment. •The defrost interval should not exceed 2 h under frost conditions

  17. Steam generator tube performance. Experience with water-cooled nuclear power reactors during 1985

    International Nuclear Information System (INIS)

    The performance of steam generator tubes at water-cooled reactors during 1985 has been reviewed. Seventy-three of 168 reactors in the survey experienced tube degradation sufficient for the tubes to be plugged. The number of tubes plugged was 6837 or 0.28% of those in service. The leading cause of tube failure was stress corrosion cracking from the primary side. Stress corrosion cracking or intergranular attack from the secondary side and pitting were also major causes of tube failure. Unlike most previous years, fretting was a substantial problem at some reactors. Overall, corrosion continued to account for more than 80% of the defects. 20 refs

  18. Performance and optimum design analysis of longitudinal and pin fins with simultaneous heat and mass transfer: Unified and comparative investigations

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Balaram [Department of Mechanical Engineering, Jadavpur University, Raja SC Mallick Road, Kolkata 700 032, West Bengal (India)

    2007-04-15

    In the present paper, the thermal analysis and optimization of longitudinal and pin fins of uniform thickness subject to fully wet, partially wet and fully dry surface conditions are carried out analytically, and also a comparative study is made between the longitudinal and pin fin for a wide range of design parameters. From the results, a significant effect on the temperature distribution in the fin and the fin efficiency with the variations in moist air psychometric conditions is noticed. For partially wet fins, the length of the wet-dry interface depends on the relative humidity RH, fin parameter Z{sub d} and geometry of the fin. From the results, it can also be highlighted that for the same thermo-geometric and psychometric parameters, a longitudinal fin gives higher efficiency than the corresponding pin fin irrespective of surface conditions. Next, a generalized scheme for optimization has been demonstrated in such a way that either heat transfer duty or fin volume can be taken as a constraint selected as per design requirement. From the optimization results, it can be pointed out that the optimum design of both the longitudinal and pin fin under the partially wet surface condition is only possible for a narrow range of relative humidity whereas for the fully wet surface, a wide range is noticed. Finally, design curves have been established for a wide range of thermo-psychometric parameters, which may be helpful to a designer for estimation of the optimum design variables of a fin with a minimum effort. (author)

  19. Laminar condensation heat transfer inside inclined tubes

    International Nuclear Information System (INIS)

    The problem of heat transfer during condensation of saturated refrigerant--12 vapor in both smooth and internally finned tubes was investigated. The effects of tube inclination and different tube diameter to tube length ratios are examined. Experimental results are in good agreement with theoretical predictions in the case of smooth tubes while significant improvements in heat transfer rate are obtained with internally finned tubes

  20. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1979

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1979. Tube failures occurred at 38 of the 93 reactors surveyed. Causes of these failures and procedures designed to deal with them are described. The defect rate was twice that in 1978 but still lower than the two previous years. Methods being employed to detect defects include increasing use of multifrequency eddy-current testing and a trend to full-length inspection of all tubes. To reduce the incidence of tube failures by corrosion, plant operators are turning to full-flow condensate demineralization and more leak-resistant condenser tubes. (author)

  1. Critical heat flux test on saw-toothed fin duct under one-sided heating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ezato, K. E-mail: ezatok@fusion.naka.jaeri.go.jp; Suzuki, S.; Sato, K.; Taniguchi, M.; Hanada, M.; Araki, M.; Akiba, M

    2001-10-01

    Critical heat flux (CHF) tests on a new type of rectangular cooling tube, 'saw-toothed fin duct, SFD' for high heat flux components were performed under one-sided heating conditions. The tube has internal triangle fins at the heating side to enhance the CHF characteristics. Hydraulic conditions were as follows: axial flow velocity ranged from 2 to 12 m/s. Local pressure at the center of the test sample was 1 MPa and inlet water temperature was 21-25 deg. C. In the present work, SFD, which has a fin height of 3.46 mm and an installation angle of the fin of 70 deg., results in the highest CHF of 43 MW/m{sup 2} at the axial flow velocity of 10 m/s. This value is 1.3 times higher than that obtained with a Hypervapotron.

  2. Threshold Voltage Sensitivity to Metal Gate Work-Function Based Performance Evaluation of Double-Gate n-FinFET Structures for LSTP Technology

    Directory of Open Access Journals (Sweden)

    M. R. Beigh

    2013-03-01

    Full Text Available This paper investigates the threshold voltage sensitivity to metal gate work-function for n-channel double gate fin field-effect transistor (FinFET structures and evaluates the short channel performance of the device using threshold voltage dependence on metal gate work-function analysis. We carried out the study for a double gate n-channel fin field-effect transistor (n-FinFET with parameters as per the projection report of International Technology Roadmap for Semiconductors, ITRS-2011 for low standby power (LSTP 20 nm gate length technology node. In the present study device simulation have been carried out using PADRE simulator from MuGFET, which is based on the drift-diffusion theory. Our results show the accuracy and validity of classical drift-diffusion simulation results for transistor structures with lateral dimensions 10nm and above. The subthreshold behavior of device improves with increased metal gate work-function. The results also show that a higher gate work-function (?5 eV can fulfill the tolerable off-current as projected in ITRS 2011 report. The SCE in FinFET can reasonably be controlled and improved by proper adjustment of the metal gate work-function. DIBL is reduced with the increase in gate work function.

  3. Effect of the conical-shape on the performance of vortex tube

    Science.gov (United States)

    Guen, M.; Natkaniec, C.; Kammeyer, J.; Seume, J. R.; Adjlout, L.; Imine, O.

    2013-04-01

    The present study focuses on the effect of conical shape in the cold side of the Ranque-Hilsch vortex tube which is shown to have a considerable influence on the system performance. A vortex tube is a simple circular tube with no moving parts which is capable to divide a high pressure flow into two relatively lower pressure flows with temperatures higher and lower than the incoming flow. A three-dimensional computational fluid dynamic model is used to analyse the mechanisms of flow inside a vortex tube. The SST turbulence model is used to predict the turbulent flow behaviour inside the vortex tube. The geometry of a vortex tube with circumferential inlet slots as well as axial cold and hot outlet is considered. Performance curves temperature separation versus cold outlet mass fraction are calculated for a given inlet mass flow rate and varying outlet mass flow rates.

  4. Study of the thermal performance of external and internal finned plate-heat exchangers for nuclear steam generator application

    International Nuclear Information System (INIS)

    The present study points out two main categories of steam generators for nuclear plants with PWR reactor, on one side of the Babcok and Wilcox type, and on the other side of the Westinghouse type. The present study examines, from a recent patent, the possibility to add internal and external fins in the steam generator exchangers of PWR reactors. The finned-plate heat exchanger is first described. The thermal characteristics of a finned-plate and of an exchanger including these plates are tested. The theoretical study and the experiment are both presented. The study deals more particularly with the evaluation of the global heat exchange coefficient that the internal fins allow to improve. The experiment has been carried out for different flow rates and at different temperatures

  5. Condensation of Refrigerant-11 on the outside of horizontal and inclined enhanced tubes

    Energy Technology Data Exchange (ETDEWEB)

    Domingo, N.

    1982-12-01

    Heat transfer condensation tests with Refrigerant-11 were performed on the outside of a smooth tube and a variety of enhanced tubes oriented horizontally and at various tube inclinations. One smooth tube and seven enhanced (externally fluted, roped, spiraled, and externally finned) tubes of 2.54-cm (1-in.) nominal outside diameter and 1.17-m (4-ft) length were tested. Several of the tested tubes featured internal enhanced geometries, which were caused by the heat transfer enhancing geometry on the tube's external surface. Condensing heat transfer coefficients are reported as composite coefficients, which combine the resistance of the condensing film and the tube wall, and are based on total tube outside surface area. Results show that in the horizontal condensing mode, the rank order (best to worst) of the tube geometries tested was spiral-shaped tubes, rope-shaped tubes, smooth tube, externally finned tube, and externally fluted tube. For a spiral-shaped tube, horizontal composite coefficients were up to 2.0 times the corresponding horizontal smooth tube values. For tilt angles greater than or equal to 60/sup 0/ from the horizontal, the condensing performance of the externally fluted tube was best of all the tubes tested.

  6. Investigation Of The Dynamic Performances Of A New Picosecond Streak Tube

    Science.gov (United States)

    Guofu, Chen; Zhongren, Chen; Xianhua, Wang; Youlai, Ren

    1985-02-01

    This paper describes the principles and methods of dynamic test. Some results of the dynamic performances of a new picosecond streak tube will be presented. When the input pho-tocathode is illuminated by laser pulses ( 0.53,x,(, m, 5ps ) from a passively modelocked Nd;glass laser, the temporal resolution of the streak tube is better than 3ps, and the dynamic range of the streak tube is about 32.

  7. Steam-generator tube performance: world experience with water-cooled nuclear power reactors during 1978

    International Nuclear Information System (INIS)

    The performance of steam-generator tubes in water-cooled nuclear power reactors during 1978 is reviewed. Tube failures occurred at 31 of the 86 reactors surveyed. The causes of these failures and the procedures designed to deal with them are described. The number of tubes plugged has decreased dramatically in 1978 compared to the previous year. This is attributed to the diligent application of techniques developed through in-plant experience and research and development programs over the past several years

  8. AIRS PFM Pulse Tube Cooler System-level Performance

    Science.gov (United States)

    Ross, R.; Johnson, D.; Collins, S.; Green, K.; Wickman, H.

    1998-01-01

    JPL's Atmospheric Infrared Sounder (AIRS) instrument is being built to make precision measurements of air temperature over the surface of the Earth as a function of elevation; the flight instrument is in the final stages of assembly and checkout at this time, and uses a pair of TRW pulse tube cryocoolers operating at 55K to cool its sensitive IR focal plane.

  9. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1983 and 1984

    International Nuclear Information System (INIS)

    A review of the performance of steam generator tubes in water-cooled nuclear power reactors showed that tubes were plugged at 47 (35.6%) of the reactors in 1983 and at 63 (42.6%) of the reactors during 1984. In 1983 and 1984 3291 and 3335 tubes, respectively, were removed from service, about the same as in 1982. The leading causes assigned to tube failure were stress corrosion cracking from the primary side and stress corrosion cracking or intergranular attack from the secondary side. In addition 5668 tubes were repaired for further service by installation of internal sleeves. Most of these were believed to have deteriorated by one of the above mechanisms or by pitting. There is a continuing trend towards high-integrity condenser tube materials at sites cooled by brackish or sea water. 31 refs

  10. Improving the RF Performance of Carbon Nano tube Field Effect Transistor

    International Nuclear Information System (INIS)

    Compact model of single-walled semiconducting carbon nano tube field-effect transistors (CNTFETs) implementing the calculation of energy conduction subband minima under VHDLAMS simulator is used to explore the high-frequency performance potential of CNTFET. The cutoff frequency expected for a MOSFET-like CNTFET is well below the performance limit, due to the large parasitic capacitance between electrodes. We show that using an array of parallel nano tubes as the transistor channel combined in a finger geometry to produce a single transistor significantly reduces the parasitic capacitance per tube and, thereby, improves high-frequency performance.

  11. Heat transfer performance of condenser tubes in an MSF desalination system

    Energy Technology Data Exchange (ETDEWEB)

    Galal, T.; Kalendar, A.; Al Saftawi, A.; Zedan, M. [Public Authority for Applied Education and Training, Shuwaikh (Kuwait)

    2010-11-15

    The present research examines the amount of condensed fresh water off the outer-side surface of heat exchangers in an MSF system. The quantitative modeling of condensed water on the outer surface of comparable tubes, enhanced and plain, in a simulated MSF technique is investigated. An adapted simulation design on a test-rig facility, accounting for the condenser tubing in actual industrial desalination plate-form, is used with corrugated and smooth aluminum-brass material tubes 1100mm long and 23mm bore. A single phase flow of authentic brine water that typifies real fouling is utilized to simulate the actual environmental life of a multi-stage flashing desalination system, with coolant flow velocity 0.1 m/s in the two delineated types of condenser tubing. It is demonstrated that the condensate water amount from the specified enhanced tube is about 1.22 times the condensate water amount from the smooth tube, adaptive for 140 running hours under deliberated constrains. The topic covers a comparative analysis of thermal performance. Comparing results with fresh water confirm the effect of fouling on significantly lowering the value of the overall heat transfer coefficient versus time. Fouling resistance R{sub f} is reported with the critical coolant flow speed of 0.1 m/s. Comparison between the fouling resistance for both smooth and corrugated tubes versus time is performed. The fouling thermal resistance of the corrugated tube is 0.56 of the fouling thermal resistance of the smooth tube after140 running hours of the experiment are concluded. Overall, in the case of real brine, results prove that heat performance for the corrugated tube is superior to the plain tube over the studied time period (140 hrs) for the chosen range of flow speeds

  12. Effect of marine biofouling on the heat transfer performance of titanium condenser tubes

    International Nuclear Information System (INIS)

    The fouling of the sea water side surfaces of condenser tubes lowers their heat transfer and affects the efficiency of thermal and nuclear power stations. Recently, with the rise of energy cost, the economical and technical interests on this problem have increased. Titanium tubes have very excellent corrosion resistance in sea water, but are apt to undergo biofouling since they are non-poisonous. In this study, titanium tubes and aluminum brass tubes were compared regarding biofouling, and as the countermeasures, the effect of the frequent cleaning with Carborundum balls was compared with other methods. On the basis of these results, the heat transfer performance of the titanium tubes cleaned frequently with Carborundum balls was examined. A model condenser in the Atsumi Power Station, Chubu Electric Power Co., Inc., was used for the experiment. The experiment was commenced on November 6, 1976, and finished on April 5, 1979. The tubes tested, the test conditions, and the measurement of the coefficient of overall heat transmission and the calculation of the fouling factor are explained. For the prevention of the biofouling of titanium tubes, the frequent cleaning with Carborundum balls was very effective, and these titanium tubes showed the same coefficient of overall heat transmission as the aluminum brass tubes cleaned with sponge balls. (Kako, I.)

  13. Test for Fauske and Associates to perform tube propagation experiments with simulated Hanford tank wastes

    International Nuclear Information System (INIS)

    This test plan, prepared at Pacific Northwest National Laboratory for Westinghouse Hanford Company, provides guidance for performing tube propagation experiments on simulated Hanford tank wastes and on actual tank waste samples. Simulant compositions are defined and an experimental logic tree is provided for Fauske and Associates (FAI) to perform the experiments. From this guidance, methods and equipment for small-scale tube propagation experiments to be performed at the Hanford Site on actual tank samples will be developed. Propagation behavior of wastes will directly support the safety analysis (SARR) for the organic tanks. Tube propagation may be the definitive tool for determining the relative reactivity of the wastes contained in the Hanford tanks. FAI have performed tube propagation studies previously on simple two- and three-component surrogate mixtures. The simulant defined in this test plan more closely represents actual tank composition. Data will be used to support preparation of criteria for determining the relative safety of the organic bearing wastes

  14. Effect of Diameter of Orifice and Nozzle on the Performance of Counter Flow Vortex Tube

    OpenAIRE

    Prabakaran J; Vaidyanathan S

    2010-01-01

    Vortex tube is a simple device which will generates cold air stream and hot air stream from the source of compressed air. When high pressure air is injected via tangential nozzle a strong vortex flow will be created which will be split into two air streams. The main factors that affecting the performance of vortex tubes are inlet pressure, L/D ratio, cold mass fraction, diameter of nozzle and orifice. In this paper the performance of the vortex tube is investigated with different diameters of...

  15. Effect of Diameter of Orifice and Nozzle on the Performance of Counter Flow Vortex Tube

    Directory of Open Access Journals (Sweden)

    Prabakaran.J

    2010-04-01

    Full Text Available Vortex tube is a simple device which will generates cold air stream and hot air stream from the source of compressed air. When high pressure air is injected via tangential nozzle a strong vortex flow will be created which will be split into two air streams. The main factors that affecting the performance of vortex tubes are inlet pressure, L/D ratio, cold mass fraction, diameter of nozzle and orifice. In this paper the performance of the vortex tube is investigated with different diameters of orifice and nozzle.

  16. Relationship between pressure tube processing, impurity/alloying element concentrations and performance in CANDU reactors

    International Nuclear Information System (INIS)

    In a CANDU reactor, pressure tubes of cold-worked Zr-2.5 Nb material are used in the reactor core to contain the fuel bundles and the heavy water (D2O) coolant. Under normal operating conditions the pressure tubes are exposed to an operating environment of high fast neutron flux, D2O coolant flow rate and temperature for up to 30 years. To ensure that these tubes will perform acceptably over their design life in such an environment, their behaviour has been monitored in relation two variations in the manufacturing processes used to produce them and their alloying/impurity element concentrations. For example, elongation data are available for all tubes in most reactors, over 2000 deuterium concentration measurements are available from operating tubes, transverse strain profiles have been determined by inspection of approximately 100 tubes and mechanical properties, fracture toughness and microstructural data are available from about 50 tubes removed from reactors, the largest proportion of which were taken from the Pickering 3 and 4 Nuclear Generating Stations when these reactors were re-tubed. Evaluations of the information provided by these measurements of the characteristics of tubes that have seen power reactor service, combined with corresponding results from laboratory experiments of unirradiated pressure tube material and similar material irradiated in research reactors, have yielded relationships between the property changes and the manufaetween the property changes and the manufacturing process and alloying/impurity concentration levels of the tubes. This information is being exploited to improve the performance of pressure tubes in present and future CANDU reactors. For example, evidence is presented to show that reductions in Cl and, to a lesser extent, P and C, substantially increase the fracture toughness after irradiation, and that increasing the Fe concentration will result in a significant reduction in the elongation rate of the tubes. Some of the relationships found in these studies have already been factored into the pressure tube specification for recent reactors while others will be included in the near future. These changes will allow the pressure tubes to reach their design lives with greater margins

  17. Performance of a Compact Gamma Tube Interrogation Source

    Science.gov (United States)

    King, Michael J.; Antolak, Arlyn J.; Leung, Ka-Ngo; Morse, Dan H.; Raber, Thomas N.; Doyle, Barney L.

    2009-03-01

    Active interrogation with high-energy monoenergetic gammas can induce photofission signals in fissile materials while minimizing absorbed radiation dose and background from surrounding materials. A first-generation axial-type gamma generator has been developed that utilizes the 11B(p,?)12C nuclear reaction at a 163 keV resonance to produce monoenergetic 12-MeV gamma-rays. The gamma tube employs a water-cooled cylindrical radio frequency (if) induction ion source capable of producing a proton current density of up to 100 mA/cm2. The extracted proton beam bombards a lanthanum hexaboride (LaB6) target at energies up to 200 keV. The 12-MeV gamma intensity was measured as a function of proton energy, beam current, and angle. Photofission-induced neutrons from depleted uranium (DU) were measured and compared to MCNPX calculations. After extended operation, the high power density of the proton beam was observed to cause damage to the LaB6 target and the gamma tube improvements currently being made to mitigate this damage are discussed.

  18. Performance of a Compact Gamma Tube Interrogation Source

    International Nuclear Information System (INIS)

    Active interrogation with high-energy monoenergetic gammas can induce photofission signals in fissile materials while minimizing absorbed radiation dose and background from surrounding materials. A first-generation axial-type gamma generator has been developed that utilizes the 11B(p,?)12C nuclear reaction at a 163 keV resonance to produce monoenergetic 12-MeV gamma-rays. The gamma tube employs a water-cooled cylindrical radio frequency (if) induction ion source capable of producing a proton current density of up to 100 mA/cm2. The extracted proton beam bombards a lanthanum hexaboride (LaB6) target at energies up to 200 keV. The 12-MeV gamma intensity was measured as a function of proton energy, beam current, and angle. Photofission-induced neutrons from depleted uranium (DU) were measured and compared to MCNPX calculations. After extended operation, the high power density of the proton beam was observed to cause damage to the LaB6 target and the gamma tube improvements currently being made to mitigate this damage are discussed.

  19. Thermal-hydraulic performance of Vipertex 1EHT enhanced heat transfer tubes

    International Nuclear Information System (INIS)

    Heat transfer enhancement plays an important role in improving energy efficiency. Transition from laminar to turbulent flow for smooth tubes is typically assumed to occur for a Reynolds Number of approximately 2,300. Vipertex 1EHT enhanced tubes produce an early transition at Reynolds Numbers near 750 and for the same conditions they can provide the same amount of heat transfer that smooth tubes produce for flows that are twenty times greater. Low Reynolds Number flow (sometimes due to the lack of process water) is a typical process requirement in many areas of the world and can cause major design challenges. Use of Vipertex 1EHT enhanced heat transfer tubes can decrease process water requirements and provide higher performance levels within the same equipment footprint. In a comparison of the heat transfer for some constant flow rates, the Vipertex 1EHT surface can produce heat transfer increases of more than 500% when compared to smooth tubes. Advantages of the Vipertex 1EHT design (when compared to smooth tubes) include the maximization of heat transfer; minimization of operating costs; and/or minimization of the rate of surface fouling. These enhanced tubes recover more energy and provide an opportunity to advance the design of many heat transfer products. -- Highlights: • Vipertex 1EHT tubes produce heat transfer increases of almost 550% for a friction factor penalty of only 33%. • 1EHT tubes at a Re = 750 provides the same amount of heat transfer that smooth tube does for twenty times that value. • Vipertex 1EHT series of tubes provides a means to significantly advance many heat exchange processes

  20. Performance Of Window Air Conditioner Using Alternative Refrigerants With Different Configurations Of Capillary Tube

    Directory of Open Access Journals (Sweden)

    Richa Soni*1

    2014-06-01

    Full Text Available The objective of this study is to present test results on the basis of experimental data of capillary tubes for R-22 and its alternative R-410A (R-32/125, 50/50 wt.%.Three capillary tubes with different length (500mm, 900mm, and 1500 mm and inner diameter (1.3mm, 1.4mm, and 1.6mm respectively were selected as test sections. Compressor work, heat rejected in the condenser, coefficient of performance (COP and mass flow rate through capillary tubes were calculated for several ambient temperature. Compressor work, heat rejected in the condenser, coefficient of performance (COP and mass flow rate of R-410A were compared with R-22 for the same test conditions. The results of single capillary tubes were also compared with the results of combination of two capillary tubes. The air-conditioner was 1 TR unit designed for R-22 and R410A. The performance of the air-conditioner with R-410A was compared with the baseline performance of the air-conditioner with R-22.The experiment result shows that (1 the coefficient of performance (COP for R-410A is lowers than R-22. And the mass flow rate, heat rejected in the condenser and compressor work done for R-410A are higher than R-22 for all capillary tubes. (2For this experiment the combination of two capillary tubes with inner diameter of 1.4mm and length 900 mm has higher coefficient of performance (COP than single capillary tubes with inner diameter of 1.3 mm, 1.6 mm and length 500 mm, 1500 mm respectively.(3 The coefficient of performance (COP of capillary tube with inner diameter of 1.6 mm and length 1500 mm is higher than the capillary tube with inner diameter of 1.3 mm and length 500 mm.(4 For R-22, the coefficient of performance (COP of combination of two capillary tubes with inner diameter of 1.4mm and length 900 mm is 17.10 % higher than the straight capillary tube with inner diameter of 1.3 mm and length 500 mm. And 13.07 % higher than the straight capillary tube with inner diameter of 1.6 mm and length 1500 mm at 40ºC ambient temperature. (5And for R- 410A, the coefficient of performance (COP of combination of two capillary tubes with inner diameter of 1.4mm and length 900 mm is 13.00 % higher than the straight capillary tube with inner diameter of 1.3 mm and length 500 mm. And 11.15% higher than the straight capillary tube with inner diameter of 1.6 mm and length1500 mm at 40ºC ambient temperature.

  1. The pulse tube engine: A numerical and experimental approach on its design, performance, and operating conditions

    International Nuclear Information System (INIS)

    The pulse tube engine is a simple heat engine based on the pulse tube process. Due to its simplicity it has a high potential to be applicable in waste heat usage and energy harvesting purposes. In this work, mathematical and experimental design tools are developed to study a pressurized laboratory scale pulse tube engine. The mathematical model is based on the transient numerical solution of the governing differential equations for mass, momentum and energy. The Modelica environment of SimulationX is used to solve the equations numerically and the model is employed to design the experimental test engine with helium as working fluid. The transient behavior of the pulse tube engine's underlying thermodynamic properties is studied numerically and experimentally under different design parameters as well as for different heat input temperatures, filling pressures and operating frequencies. The measured engine characteristics are compared with the calculated predictions. Internal and external power losses are quantified. Design studies for a further development of the pulse tube engine are performed experimentally. The developed numerical tool provides a rational framework for up-scaling the current laboratory model to industrial scale. - Highlights: • We developed a mathematical model and an experimental test engine to study the pulse tube engine. • The experimental test engine is able to operate with pressurized helium of up to 12 bar filling pressure. • We characterized and compared the engine's behavior under different design features and operating conditions. • Design studies for a further development of the pulse tube engine are performed experimentally

  2. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1978

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1978. Tube failures occurred at 31 of the 86 reactors surveyed. Causes of these failures and procedures designed to deal with them are described. A dramatic decrease in the number of tubes plugged was evident in 1978 compared to the previous year. This is attributed to diligent application of techniques developed from in-plant experience and research and development programs over the past several years. (auth)

  3. Performance Of Window Air Conditioner Using Alternative Refrigerants With Different Configurations Of Capillary Tube

    OpenAIRE

    Richa Soni*1; , P.K. Jhinge & R.C. Gupta2

    2014-01-01

    The objective of this study is to present test results on the basis of experimental data of capillary tubes for R-22 and its alternative R-410A (R-32/125, 50/50 wt.%).Three capillary tubes with different length (500mm, 900mm, and 1500 mm) and inner diameter (1.3mm, 1.4mm, and 1.6mm respectively) were selected as test sections. Compressor work, heat rejected in the condenser, coefficient of performance (COP) and mass flow rate through capillary tubes were calculated for several...

  4. Effect of Geometric Modifications on the Performance of Vortex Tube - A Review

    Directory of Open Access Journals (Sweden)

    O. M. Kshirsagar

    2014-11-01

    Full Text Available The vortex tube is device, which produces hot and cold air streams simultaneously at its two ends from a source of compressed air without any moving part. Literature review of this paper is to understand the effect of various parameters like inlet pressure of air, number of nozzles, cold orifice diameter and hot end valve angle on the performance of vortex tube. Also by the literature review it is clear that there is no theory so perfect, which gives the satisfactory explanation of the vortex tube phenomenon. Due to this reason researcher conduct the series of experimentation to understand the effect of various parameters mentioned above on the performance of vortex tube.

  5. Does size matter? An assessment of quota market evolution and performance in the Great Barrier Reef fin-fish fishery

    OpenAIRE

    James Innes; Olivier Thébaud; Ana Norman-López; L. Richard Little

    2014-01-01

    In fisheries managed using individual transferable quotas (ITQs) it is generally assumed that quota markets are well-functioning, allowing quota to flow on either a temporary or permanent basis to those able to make best use of it. However, despite an increasing number of fisheries being managed under ITQs, empirical assessments of the quota markets that have actually evolved in these fisheries remain scarce. The Queensland Coral Reef Fin-Fish Fishery (CRFFF) on the Great Barrier Reef has bee...

  6. Performance studies of tubular flat plate collectors

    International Nuclear Information System (INIS)

    Computations have been performed for flat plate efficiency factor, heat removal factor, heat gained by fluid for different materials used for the tubes and fins of flat plate tubular solar collectors. 3 refs, 17 figs, 4 tabs

  7. Steam generator tube performance: experience with water-cooled nuclear power reactors during 1977

    International Nuclear Information System (INIS)

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1977. Failures were reported in 34 of the 79 reactors surveyed. Causes of these failures and inspection and repair procedures designed to deal with them are presented. Although corrosion remained the leading cause of tube failures, specific mechanisms have been identified and methods of dealing with them developed. These methods are being applied and should lead to a reduction of corrosion failures in future. (author)

  8. Medical Thoracoscopy Performed Using a Flexible Bronchoscope Inserted through a Chest Tube under Local Anesthesia

    OpenAIRE

    Toshinobu Yokoyama; Reiko Toda; Ryusuke Tomioka; Hisamichi Aizawa

    2009-01-01

    Background and Objectives. Many cases of pleural effusion can remain undiagnosed following thoracentesis. We evaluated our own technique for performing thoracoscopy under local anesthesia using a 32?Fr chest tube and a flexible fiberoptic bronchoscope without a rigid thoracoscope for the diagnosis, inspection, and management of patients with pleurisy. Methods. Seven patients with pleural effusion who underwent thoracoscopy under local anesthesia using a 32?Fr chest tube and a fl...

  9. Experimental investigation of thermal-hydraulic performance of PCCS with horizontal tube heat exchangers: single U-tube test

    International Nuclear Information System (INIS)

    JAERI and JAPC started a cooperative study to verify performance of a PCCS (Passive Containment Cooling System) using horizontal heat exchanger for next-generation BWR in 1998. A test facility with a horizontal single U-tube was constructed in JAERI in 1999 to investigate fundamental condensation behavior under influences of non-condensable gas. Preliminary pre-test analyses were performed using RELAP5/ MOD3.2.1.2 code to expect the experimental outcomes by incorporating a correlation for condensation degradation because of non-condensable gas by Ueno et al. for better prediction. Preliminary results from both experiments (shakedown) and pre-test analyses indicated that the PCCS using horizontal U-tube heat exchanger is promising. Steam generated under assumed severe accident conditions; steam generation rate approx. = 1% core power, non-condensable gas concentration of 1% and simulated containment vessel pressure of 0.7 MPa, was totally condensed with a small differential pressure across inlet and outlet plenum. Experimental data will be accumulated to develop models and correlations for a better prediction of responses of the PCCS using horizontal heat exchanger during postulated severe accidents. (author)

  10. Heated ion implantation for high-performance and highly reliable silicon-on-insulator complementary metal–oxide–silicon fin field-effect transistors

    Science.gov (United States)

    Mizubayashi, Wataru; Onoda, Hiroshi; Nakashima, Yoshiki; Ishikawa, Yuki; Matsukawa, Takashi; Endo, Kazuhiko; Liu, Yongxun; O’uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Migita, Shinji; Morita, Yukinori; Ota, Hiroyuki; Masahara, Meishoku

    2015-04-01

    We have investigated the impact of heated ion implantation (I/I) on the performance and reliability of silicon-on-insulator (SOI) complementary metal–oxide–silicon (CMOS) fin field-effect transistors (FinFETs). An implantation temperature equal to and higher than 400 °C is needed to maintain the crystallinity of the Si substrate during I/I within the experimental conditions of ion species, implantation energy, and ion dose in this study. By heated I/I at 500 °C, the 11-nm-thick SOI layer perfectly maintains the crystallinity even after I/I, and a defect-free crystal is obtained by activation annealing. It was clarified that the cap layer is essential for the suppression of the out-diffusion during heated I/I. Heated I/I on the source and drain improves the on-current–off-current (Ion–Ioff), threshold voltage (Vth) variability, and bias temperature instability (BTI) characteristics of nMOS and pMOS FinFETs as compared with those after room-temperature I/I.

  11. Optimization of counter flow Ranque-Hilsch vortex tube performance using Taguchi method

    Energy Technology Data Exchange (ETDEWEB)

    Pinar, Ahmet Murat [Celal Bayar University, Vocational High School, Department of Machinery, 45400-Turgutlu-Manisa (Turkey); Uluer, Onuralp [Gazi University, Faculty of Technical Education, Mechanical Education Department, Teknikokullar, 06503 Ankara (Turkey); Kirmaci, Volkan [Bartin University, Faculty of Engineering, Mechanical Engineering Department, 74100 Bartin (Turkey)

    2009-09-15

    This study discusses the application of Taguchi method in assessing maximum temperature gradient for the Ranque-Hilsch counter flow vortex tube performance. The experiments were planned based on Taguchi's L27 orthogonal array with each trial performed under different conditions of inlet pressure, nozzle number and fluid type. Signal-to-noise ratio (S/N) analysis, analysis of variance (ANOVA) and regression analysis were carried out in order to determine the effects of process parameters and optimal factor settings. Finally, confirmation tests verified that Taguchi method achieved optimization of counter flow Ranque-Hilsch vortex tube performance with sufficient accuracy. (author)

  12. HEAT TRANSFER EVALUATION OF HFC-236EA WITH HIGH PERFORMANCE ENHANCED TUBES IN CONDENSATION AND EVAPORATION

    Science.gov (United States)

    The report gives results of an evaluation of the heat transfer performance of pure hydrofluorocarbon (HFC)-236ea for high performance enhanced tubes which had not been previously used in Navy shipboard chillers. Shell-side heat transfer coefficient data are presented for conde...

  13. Performance characteristics of the pulsed high power klystron tube for PLS 2-GeV Linac

    International Nuclear Information System (INIS)

    PLS 2-GeV Linac employs the E-3712 klystron tubes manufactured by TOSHIBA as one of the pulsed high power microwave sources. The rated power of the tube is 80-MW at 4 ps pulse width with 6OHz pulse repetition rate. As a part of the main linac the authors have completed the installation of two units of the E-3712 klystron tubes and the matching 200-MW modulators together with the accompanying waveguide networks and the accelerating columns. Since all the components are exposed as a virgin to high power microwave, careful power conditioning procedures are underway. The rest of linac components installation is also underway. The authors present the performance characteristics of the E-3712 klystron tube measured with the water load. The result of the initial power conditioning operation for the waveguide network and the accelerating structures installed as a part of the PLS 2-GeV linac is also presented

  14. Steady-state and transient heat transfer through fins of complex geometry

    Directory of Open Access Journals (Sweden)

    Taler Dawid

    2014-06-01

    Full Text Available Various methods for steady-state and transient analysis of temperature distribution and efficiency of continuous-plate fins are presented. For a constant heat transfer coefficient over the fin surface, the plate fin can be divided into imaginary rectangular or hexangular fins. At first approximate methods for determining the steady-state fin efficiency like the method of equivalent circular fin and the sector method are discussed. When the fin geometry is complex, thus transient temperature distribution and fin efficiency can be determined using numerical methods. A numerical method for transient analysis of fins with complex geometry is developed. Transient temperature distributions in continuous fins attached to oval tubes is computed using the finite volume - finite element methods. The developed method can be used in the transient analysis of compact heat exchangers to calculate correctly the heat flow rate transferred from the finned tubes to the fluid.

  15. Procedimiento para el cálculo de circuitos en el modelado del flujo en intercambiadores de calor de aletas y tubos / Procedure for Calculating Circuits in the Modeling of Flow in fin-and-tube Heat Exchangers

    Scientific Electronic Library Online (English)

    Edwin, Córdoba-Tuta; David, Fuentes-Díaz.

    2015-01-01

    Full Text Available En este trabajo se presenta un procedimiento general para la simulación del comportamiento del flujo en los intercambiadores de tubos y aletas con una gran flexibilidad en el manejo de la información. Este procedimiento está basado en el uso de Programación Orientada a Objetos y específicamente al u [...] so de C++, esto debido a todas las ventajas de este tipo de programación. La entrada de datos se lleva a cabo por medio de archivos, de forma que programas de terceros puedan generar la configuración del intercambiador y permitir calcular el intercambiador en forma paramétrica. Los resultados para el análisis se presentan en tres formatos diferentes: valores separados por comas (CSV), texto plano estructurado y autodocumentado (XML) y un formato para la visualización gráfica de resultados (VTK). Abstract in english This paper presents a general method for simulating the flow behavior in the fin-and-tube heat exchangers with high flexibility in handling the information. This procedure is based on the use of Object-Oriented Programming and specifically using C++, this because of all the advantages of this type o [...] f programming. Data entry is carried out by files, so that third-party programs can generate configuration and permit calculation in parametric form. The results for the analysis are presented in three different formats: comma separated value (CSV), structured plain text and self-documenting (XML) and a graphical display of results (VTK).

  16. High Fin Width Mosfet Using Gaa Structure

    Directory of Open Access Journals (Sweden)

    S.L.Tripathi

    2012-11-01

    Full Text Available This paper describes the design and optimization of gate-all-around (GAA MOSFETs structures. The optimum value of Fin width and Fin height are investigated for superior subthreshold behavior. Also the performance of Fin shaped GAA with gate oxide HfO2 are simulated and compared with conventional gate oxide SiO2 for the same structure. As a result, it was observed that the GAA with high K dielectric gate oxide has more possibility to optimize the Fin width with improved performance. All the simulations are performed on 3-D TCAD device simulator.

  17. Performance demonstration tests for eddy current inspection of steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

    1996-05-01

    This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given.

  18. Performance demonstration tests for eddy current inspection of steam generator tubing

    International Nuclear Information System (INIS)

    This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given

  19. The effect of fins on vortex shedding from a cylinder in cross-flow

    International Nuclear Information System (INIS)

    A bare tube and three segmented-finned tubes have been tested to investigate the effect of the fins on vortex shedding from cylinders in cross-flow. The addition of the fins is found to enhance the process of vortex shedding. It is shown that the fins increase the correlation length and the amplitude of velocity fluctuation at the vortex shedding frequency. The fins also increase the non-linear nature of the flow in the wake, as evidenced by a remarkable increase in the number and in the amplitude of the higher harmonic components of vortex shedding. However, the correlation length in the wake of the finned tubes is found to change with angular rotation of the tube around its axis. This phenomenon seems to be related to an irregular wavy pattern of the fin distribution along the tube axis. (authors)

  20. Performance improvement of double-tube gas cooler in CO2 refrigeration system using nanofluids

    Directory of Open Access Journals (Sweden)

    Sarkar Jahar

    2015-01-01

    Full Text Available The theoretical analyses of the double-tube gas cooler in transcritical carbon dioxide refrigeration cycle have been performed to study the performance improvement of gas cooler as well as CO2 cycle using Al2O3, TiO2, CuO and Cu nanofluids as coolants. Effects of various operating parameters (nanofluid inlet temperature and mass flow rate, CO2 pressure and particle volume fraction are studied as well. Use of nanofluid as coolant in double-tube gas cooler of CO2 cycle improves the gas cooler effectiveness, cooling capacity and COP without penalty of pumping power. The CO2 cycle yields best performance using Al2O3-H2O as a coolant in double-tube gas cooler followed by TiO2-H2O, CuO-H2O and Cu-H2O. The maximum cooling COP improvement of transcritical CO2 cycle for Al2O3-H2O is 25.4%, whereas that for TiO2-H2O is 23.8%, for CuO-H2O is 20.2% and for Cu-H2O is 16.2% for the given ranges of study. Study shows that the nanofluid may effectively use as coolant in double-tube gas cooler to improve the performance of transcritical CO2 refrigeration cycle.

  1. The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance

    Science.gov (United States)

    ATLAS TRT Collaboration; Abat, E.; Addy, T. N.; Åkesson, T. P. A.; Alison, J.; Anghinolfi, F.; Arik, E.; Arik, M.; Atoian, G.; Auerbach, B.; Baker, O. K.; Banas, E.; Baron, S.; Bault, C.; Becerici, N.; Beddall, A.; Beddall, A. J.; Bendotti, J.; Benjamin, D. P.; Bertelsen, H.; Bingul, A.; Blampey, H.; Bocci, A.; Bochenek, M.; Bondarenko, V. G.; Bychkov, V.; Callahan, J.; Capeáns Garrido, M.; Cardiel Sas, L.; Catinaccio, A.; Cetin, S. A.; Chandler, T.; Chritin, R.; Cwetanski, P.; Dam, M.; Danielsson, H.; Danilevich, E.; David, E.; Degenhardt, J.; Di Girolamo, B.; Dittus, F.; Dixon, N.; Dogan, O. B.; Dolgoshein, B. A.; Dressnandt, N.; Driouchi, C.; Ebenstein, W. L.; Eerola, P.; Egede, U.; Egorov, K.; Evans, H.; Farthouat, P.; Fedin, O. L.; Fowler, A. J.; Fratina, S.; Froidevaux, D.; Fry, A.; Gagnon, P.; Gavrilenko, I. L.; Gay, C.; Ghodbane, N.; Godlewski, J.; Goulette, M.; Gousakov, I.; Grigalashvili, N.; Grishkevich, Y.; Grognuz, J.; Hajduk, Z.; Hance, M.; Hansen, F.; Hansen, J. B.; Hansen, P. H.; Hare, G. A.; Harvey, A., Jr.; Hauviller, C.; High, A.; Hulsbergen, W.; Huta, W.; Issakov, V.; Istin, S.; Jain, V.; Jarlskog, G.; Jeanty, L.; Kantserov, V. A.; Kaplan, B.; Kapliy, A. S.; Katounine, S.; Kayumov, F.; Keener, P. T.; Kekelidze, G. D.; Khabarova, E.; Khristachev, A.; Kisielewski, B.; Kittelmann, T. H.; Kline, C.; Klinkby, E. B.; Klopov, N. V.; Ko, B. R.; Koffas, T.; Kondratieva, N. V.; Konovalov, S. P.; Koperny, S.; Korsmo, H.; Kovalenko, S.; Kowalski, T. Z.; Krüger, K.; Kramarenko, V.; Kudin, L. G.; LeBihan, A.-C.; LeGeyt, B. C.; Levterov, K.; Lichard, P.; Lindahl, A.; Lisan, V.; Lobastov, S.; Loginov, A.; Loh, C. W.; Lokwitz, S.; Long, M. C.; Lucas, S.; Lucotte, A.; Luehring, F.; Lundberg, B.; Mackeprang, R.; Maleev, V. P.; Manara, A.; Mandl, M.; Martin, A. J.; Martin, F. F.; Mashinistov, R.; Mayers, G. M.; McFarlane, K. W.; Mialkovski, V.; Mills, B. M.; Mindur, B.; Mitsou, V. A.; Mjörnmark, J. U.; Morozov, S. V.; Morris, E.; Mouraviev, S. V.; Muir, A. M.; Munar, A.; Nadtochi, A. V.; Nesterov, S. Y.; Newcomer, F. M.; Nikitin, N.; Novgorodova, O.; Novodvorski, E. G.; Ogren, H.; Oh, S. H.; Oleshko, S. B.; Olivito, D.; Olszowska, J.; Ostrowicz, W.; Passmore, M. S.; Patrichev, S.; Penwell, J.; Perez-Gomez, F.; Peshekhonov, V. D.; Petersen, T. C.; Petti, R.; Placci, A.; Poblaguev, A.; Pons, X.; Price, M. J.; hne, O. Rø; Reece, R. D.; Reilly, M. B.; Rembser, C.; Romaniouk, A.; Rousseau, D.; Rust, D.; Ryabov, Y. F.; Ryjov, V.; Söderberg, M.; Savenkov, A.; Saxon, J.; Scandurra, M.; Schegelsky, V. A.; Scherzer, M. I.; Schmidt, M. P.; Schmitt, C.; Sedykh, E.; Seliverstov, D. M.; Shin, T.; Shmeleva, A.; Sivoklokov, S.; Smirnov, S. Yu; Smirnova, L.; Smirnova, O.; Smith, P.; Sosnovtsev, V. V.; Sprachmann, G.; Subramania, S.; Suchkov, S. I.; Sulin, V. V.; Szczygiel, R. R.; Tartarelli, G.; Thomson, E.; Tikhomirov, V. O.; Tipton, P.; Valls Ferrer, J. A.; Van Berg, R.; Vassilakopoulos, V. I.; Vassilieva, L.; Wagner, P.; Wall, R.; Wang, C.; Whittington, D.; Williams, H. H.; Zhelezko, A.; Zhukov, K.

    2008-02-01

    A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability.

  2. An investigation of turbulent convection heat transfer performance in spiral spring coil inserted tubes

    International Nuclear Information System (INIS)

    This paper presents the results of the experimental investigation on heat transfer and fluid friction characteristics of a class of spiral spring coil used as a tube side forced convection heat transfer augmentation devices. Based on a lot of experimental data, the heat transfer correlation and fluid friction correlation revised by temperature were reached in terms of linear regression. At the same time, proper criteria were used to evaluate the economic performance of the spiral spring inserted tube according to the demand of practical application and some probing analysis were made

  3. Statistical analysis of duplex-tube performance in Experimental Breeder Reactor II superheater SU-712

    International Nuclear Information System (INIS)

    A detailed investigation was made of historical data recorded at Experimental Breeder Reactor II during operation with superheater SU-712. The objective of this study was to analyze and characterize the performance of 72 duplex steam tubes that became unbonded during a long period of operation. The information processing system ANALYZE was developed to perform the required numerical manipulations, statistical analyses, and correlation analyses with a large data base containing some five million data values. The ANALYZE system was successfully employed (a) to characterize the performance of all the steam tubes in terms of frequency and relative severity of unbonding, and (b) to establish a correlation between the observed anomalous behavior of the superheater and its operating parameters. Results from this investigation were used to select sections for materials examinations and physical tests that were performed after SU-712 was removed from operation

  4. Performance of Multi-anode Photomultiplier Tubes for the LHCb RICH detectors

    International Nuclear Information System (INIS)

    An array of Multi-anode Photomultiplier Tubes (MaPMT) was evaluated for use in the LHCb Ring Imaging Cherenkov (RICH) detectors using a prototype RICH detector in a charged particle beam. The MaPMT performance was measured with different radiator gases with and without lenses. The performance of the MaPMTs in terms of photon yield and pixel cross-talk is presented

  5. Experimental characterization of thermal hydraulic performance of louvered brazed plate fin heat exchangers / Caracterización térmico-hidraulica experimental del rendimiento de intercambiadores de placa y barras con aletas ventaneadas

    Scientific Electronic Library Online (English)

    John, Turizo-Santos; Oscar, Barros-Ballesteros; Armando, Fontalvo-Lascano; Ricardo, Vasquez-Padilla; Antonio, Bula-Silvera.

    2015-03-01

    Full Text Available Las aletas tipo persianas se utilizan comúnmente en los intercambiadores de calor compactos para aumentar el área de superficie, la turbulencia, y producir una regeneración de la capa límite requerido para mejorar el rendimiento de transferencia de calor sin un aumento significativo en la caída de p [...] resión en comparación con otro tipo aletas. Un estudio experimental sobre la transferencia de calor y la caída de presión del lado del aire en aletas tipo persiana con patrón simétrico usada en intercambiadores de calor de placas soldadas, ha sido llevado a cabo. El números de Reynolds osciló entre 350 - 1270, basado en el pitch de la aleta, mientras se mantuvo un caudal de agua constante de 1,82 m³/h. La transferencia de calor y caída de presión para la geometría probada se presenta en términos del factor de Colburn (j) y el factor de fricción de Fanning (f) como función del número de Reynolds. Los resultados experimentales para j y f presentan un comportamiento acorde comparados con los modelos de regresión sugeridos para intercambiadores de calor compactos con aletas tipo persiana y tubos planos, presentando una desviación de 5,48 % y 5,39 % respectivamente. Por otra parte, cuando se compara con el análisis de CFD para la misma geometría, se obtiene una desviación media de 6,3%. Por último, un modelo de regresión para los factores j y f se logró con base en el número de Reynolds, presentando una desviación de 1,51 % y 2,19 % respectivamente. Abstract in english Louvered fins are commonly used in compact heat exchangers to increase the surface area, turbulence, and initiate new boundary layer growth required to improve the heat transfer performance without a significant increase in pressure drop compared with other fins. An experimental study on the air sid [...] e heat transfer and pressure drop characteristics for a louvered fin with symmetrical patterns in brazed plate heat exchangers had been performed. Reynolds numbers ranged from 350 - 1270, based on the louver pitch while a constant 1.82 m3/h water flow was held. The heat transfer and pressure drop for the geometry tested was reported in terms of Colburn factor (j) and Fanning friction factor (f) as a function of the Reynolds number. The experimental results for j and f are in good agreement compared to regression models suggested for compact heat exchanger with louvered fin and flat tubes, obtaining a deviation of 5.48% and 5.39% respectively. Moreover, when compared to CFD analysis for the same geometry, an average deviation of 6.3% is obtained. Finally a regression model for j and f factors was attained based on the Reynolds number, presenting a deviation of 1.51% and 2.19% respectively.

  6. Comparative feeding kinematics and performance of odontocetes: belugas, Pacific white-sided dolphins and long-finned pilot whales.

    Science.gov (United States)

    Kane, E A; Marshall, C D

    2009-12-01

    Cetaceans are thought to display a diversity of feeding modes that are often described as convergent with other more basal aquatic vertebrates (i.e. actinopterygians). However, the biomechanics of feeding in cetaceans has been relatively ignored by functional biologists. This study investigated the feeding behavior, kinematics and pressure generation of three odontocetes with varying feeding modes (belugas, Delphinapterus leucas; Pacific white-sided dolphins, Lagenorhynchus obliquidens; and long-finned pilot whales, Globicephala melas). Four feeding phases were recognized in all odontocetes: (I) preparatory, (II) jaw opening, (III) gular depression, and (IV) jaw closing. Belugas relied on a feeding mode that was composed of discrete ram and suction components. Pacific white-sided dolphins fed using ram, with some suction for compensation or manipulation of prey. Pilot whales were kinematically similar to belugas but relied on a combination of ram and suction that was less discrete than belugas. Belugas were able to purse the anterior lips to occlude lateral gape and form a small, circular anterior aperture that is convergent with feeding behaviors observed in more basal vertebrates. Suction generation in odontocetes is a function of hyolingual displacement and rapid jaw opening, and is likely to be significantly enhanced by lip pursing behaviors. Some degree of subambient pressure was measured in all species, with belugas reaching 126 kPa. Functional variations of suction generation during feeding demonstrate a wider diversity of feeding behaviors in odontocetes than previously thought. However, odontocete suction generation is convergent with that of more basal aquatic vertebrates. PMID:19946072

  7. Performance comparison of the commercial CFD software for the prediction of turbulent flow through tube bundles

    International Nuclear Information System (INIS)

    Because turbulent flow through tube bundles can be found in many important industrial applications, such as PWR reactor, steam generator, CANDU calandria and lower plenum of the VHTR, extensive studies have been made both experimentally and numerically. Although recently licensing applications supported by commercial CFD software are increasing, there is no commercial CFD software which obtains a licensing from the regulatory body until now. Therefore, it is necessary to perform the systematic assessment for the prediction performance of the commercial CFD software. The main objective of the present study is to numerically simulate turbulent flow through both staggered and in line tube bundle using the two popular commercial CFD software, ANSYS CFX and FLUENT and to compare the simulation results with the experimental data for the assessment of these software's prediction performance

  8. Medical Thoracoscopy Performed Using a Flexible Bronchoscope Inserted through a Chest Tube under Local Anesthesia

    Directory of Open Access Journals (Sweden)

    Toshinobu Yokoyama

    2009-01-01

    Full Text Available Background and Objectives. Many cases of pleural effusion can remain undiagnosed following thoracentesis. We evaluated our own technique for performing thoracoscopy under local anesthesia using a 32?Fr chest tube and a flexible fiberoptic bronchoscope without a rigid thoracoscope for the diagnosis, inspection, and management of patients with pleurisy. Methods. Seven patients with pleural effusion who underwent thoracoscopy under local anesthesia using a 32?Fr chest tube and a flexible fiberoptic bronchoscope were retrospectively studied. Results. Thoracoscopy was safely performed in the diagnosis and management of pleural effusion in all cases. The visualization of the pleura, diaphragm, and lung using this instrumentation was excellent in comparison to that normally obtained during surgical thoracoscopy. A forceps biopsy of the pleura or diaphragm could therefore be easily and effectively performed. Conclusion. This technique is considered to have clinical utility as a diagnostic tool for pleurisy; furthermore, this method is safe, effective and inexpensive, not only for surgeons but also for physicians.

  9. Wave-shaping of pulse tube cryocooler components for improved performance

    Science.gov (United States)

    Antao, Dion Savio; Farouk, Bakhtier

    2014-11-01

    The method of wave-shaping acoustic resonators is applied to an inertance type cryogenic pulse tube refrigerator (IPTR) to improve its performance. A detailed time-dependent axisymmetric experimentally validated computational fluid dynamic (CFD) model of the PTR is used to predict its performance. The continuity, momentum and energy equations are solved for both the refrigerant gas (helium) and the porous media regions (the regenerator and the three heat-exchangers) in the PTR. An improved representation of heat transfer in the porous media is achieved by employing a thermal non-equilibrium model to couple the gas and solid (porous media) energy equations. The wave-shaped regenerator and pulse tube studied have cone geometries and the effects of different cone angles and the orientation (nozzle v/s diffuser mode) on the system performance are investigated. The resultant spatio-temporal pressure, temperature and velocity fields in the regenerator and pulse tube components are evaluated. The performance of these wave-shaped PTRs is compared to the performance of a non wave-shaped system with cylindrical components. Better cooling is predicted for the cryocooler using wave-shaped components oriented in the diffuser mode.

  10. Does size matter? An assessment of quota market evolution and performance in the Great Barrier Reef fin-fish fishery

    Directory of Open Access Journals (Sweden)

    James Innes

    2014-09-01

    Full Text Available In fisheries managed using individual transferable quotas (ITQs it is generally assumed that quota markets are well-functioning, allowing quota to flow on either a temporary or permanent basis to those able to make best use of it. However, despite an increasing number of fisheries being managed under ITQs, empirical assessments of the quota markets that have actually evolved in these fisheries remain scarce. The Queensland Coral Reef Fin-Fish Fishery (CRFFF on the Great Barrier Reef has been managed under a system of ITQs since 2004. Data on individual quota holdings and trades for the period 2004-2012 were used to assess the CRFFF quota market and its evolution through time. Network analysis was applied to assess market structure and the nature of lease-trading relationships. An assessment of market participants’ abilities to balance their quota accounts, i.e., gap analysis, provided insights into market functionality and how this may have changed in the period observed. Trends in ownership and trade were determined, and market participants were identified as belonging to one out of a set of seven generalized types. The emergence of groups such as investors and lease-dependent fishers is clear. In 2011-2012, 41% of coral trout quota was owned by participants that did not fish it, and 64% of total coral trout landings were made by fishers that owned only 10% of the quota. Quota brokers emerged whose influence on the market varied with the bioeconomic conditions of the fishery. Throughout the study period some quota was found to remain inactive, implying potential market inefficiencies. Contribution to this inactivity appeared asymmetrical, with most residing in the hands of smaller quota holders. The importance of transaction costs in the operation of the quota market and the inequalities that may result are discussed in light of these findings.

  11. A comparison of heat transfer enhancement in a medium temperature thermal energy storage heat exchanger using fins

    Energy Technology Data Exchange (ETDEWEB)

    Agyenim, Francis; Smyth, Mervyn [Centre for Sustainable Technologies, University of Ulster, Newtownabbey BT37 0QB (United Kingdom); Eames, Philip [Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2009-09-15

    An experimental energy storage system has been designed using a horizontal concentric tube heat exchanger incorporating a medium temperature phase change material (PCM) Erythritol, with a melting point of 117.7 C. Three experimental configurations, a control system with no heat transfer enhancement and systems augmented with circular and longitudinal fins have been studied. The results presented compare the system heat transfer characteristics using isotherm plots and temperature-time curves. The system with longitudinal fins gave the best performance with increased thermal response during charging and reduced subcooling in the melt during discharging. The experimentally measured data for the control, circular finned and longitudinal finned systems have been shown to vindicate the assumption of axissymmetry (direction parallel to the heat transfer fluid flow) using temperature gradients in the axial, radial and angular directions in the double pipe PCM system. (author)

  12. Thermal hydraulic performance analysis of a double tube bundle steam generator for a liquid metal reactor

    International Nuclear Information System (INIS)

    Highlights: ? Thermal-hydraulic performance of the double tube bundle steam generators was analyzed. ? A numerical method was used with considering properties variation and phase change. ? The separated types are about two times more efficient than the integrated types. ? The integrated types have good heat transfer rate even during small medium flow rate. - Abstract: In this study, thermal-hydraulic performance of a double tube bundle steam generator (DTBSG) using helically coiled tubes was analyzed numerically. For this purpose a one-dimensional thermal-hydraulic analysis computer program was developed. The DTBSG contains hot fluid and cold fluid tube bundles, a medium fluid and a pump for a medium fluid circulation in an SG. Heat is transferred from the hot side to the cold side through a medium fluid which fills the SG shell side. The fluids of the hot, cold and medium side are sodium, water/steam, lead-bismuth respectively. The assessment was made for four different types of the DTBSG at 200 MWt. It showed there is an optimum medium flow rate for each type and the separated bundle type have the best heat transfer efficiency (heat transfer rate per unit area) among the various DTBSG. However, it requires quite a large pumping power and the velocity of the medium fluid. The effect of a medium flow rate change is relatively small in the integrated bundle types while it is very large in the separated type. The developed program can be used for the optimum theam can be used for the optimum thermal design of a double tube bundle steam generator, which is one of the candidates for an Intermediate Heat Transport System (IHTS) simplification concept.

  13. COMPARATIVE ANALYSIS OF REVERSIBLE LOGIC BASED CARBON NANO TUBE FIELD EFFECT TRANSISTOR MULTIPLEXER PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Y. Varthamanan

    2013-01-01

    Full Text Available This study is about the design and analysis of a reversible logic based multiplexer, that is realized using carbon nano tube transistor. Reversible logic realization of the digital circuits offers numerous advantages over conventional circuit design. Power analysis was performed using HSPICE simulation software and the results are obtained for the 2Ã?1 and 4Ã?1 multiplexer transient behavior. The power consumption is also obtained. Comparative analysis was performed with the conventional CMOS multiiplexer design to validate the proposed design performance.

  14. Study on a Concentric Tube Bulb Manometer and its Performance Compared to U-shaped Manometer

    OpenAIRE

    Butt, Muhammad A.; Aamir Ijaz; Daood, Syed S.

    2007-01-01

    This paper presents comparative study of a new type of manometer called concentric tube bulb (C.T.B) manometer. Its performance of measuring differential height is studied against conventional U-shaped manometer. Pressure drops and mass flow rates are calculated by taking various systems comprising of different flow measuring devices such as orifice and venturimeters using both U- shaped and C.T.B manometers. Comparison between the physically measured values of differential pressure drops and...

  15. A model for the performance of a vertical tube condenser in the presence of noncondensable gases

    Energy Technology Data Exchange (ETDEWEB)

    Guentay, A.D.S.

    1995-09-01

    Some proposed vertical tube condensers are designed to operate at high noncondensable fractions, which warrants a simple model to predict their performance. Models developed thus far are usually non self-contained as they require the specification of the wall temperature to predict the local condensation rate. The present model attempts to fill this gap by addressing the secondary side heat transfer as well. Starting with momentum balance which includes the effect of interfacial shear stress, a Nusselt-type algebraic equation is derived for the film thickness as a function of flow and geometry parameters. The heat and mass transfer analogy relations are then invoked to deduce the condensation rate of steam onto the tube wall. Lastly, the heat transfer to the secondary side is modelled to include cooling by forced, free or mixed convection flows. The model is used for parametric simulations to determine the impact on the condenser performance of important factors such as the inlet gas fraction, the mixture inlet flowrate, the total pressure, and the molecular weight of the noncondensable gas. The model performed simulations of some experiments with pure steam and air-steam mixtures flowing down a vertical tube. The model predicts the data quite well.

  16. Performance of the CMS drift-tube chamber local trigger with cosmic rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G

    2010-01-01

    The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained with muon beams.

  17. Thermal performance of a circular tube filled with a high porous material

    International Nuclear Information System (INIS)

    This paper describes the heat transfer and flow characteristics of a heat exchanger tube filled with a high porous material. Fine copper wire (diameter: 0.5 mm) was inserted in a circular tube dominated by thermal conduction and forced convection. The porosity was from 0.98 to 1.0. Working fluid was air. Hydraulic equivalent diameter was cited as the characteristic length in Nusselt number and Reynolds number. Nusselt number and friction factor were expressed as functions of Reynolds number and porosity. Thermal performance was evaluated by the ratio of Nusselt number with and without a high porous material and the entropy generation. It was recognized that the high porous material was effective in low Reynolds number and the Reynolds number which minimized the entropy generation, existed. (author)

  18. Optical MCP image tube with a quad Timepix readout: initial performance characterization

    International Nuclear Information System (INIS)

    A photon counting, microchannel plate (MCP) optical imaging tube has been fabricated using a 2 × 2 array of Timepix application specific integrated circuits (ASICs) as the readout anode. A Timepix ASIC is a 256 × 256 pixellated CMOS readout chip with each pixel containing an amplifier, discriminator and counter. The counter values, representing either time of arrival, total count or time over threshold, can record the position and time of arrival of the electron pulses from the MCP if the charge collected on its input pads exceed the adjustable lower threshold value. Below we present initial results of the tube's performance, the quantum efficiency of the bi-alkali photocathode, uniformity of response, spatial and temporal resolution, and dynamic range. Planned improvement to the design based on the new Timepix3 chip will be discussed

  19. Heat transfer performance during condensation of R-134a inside helicoidal tubes

    International Nuclear Information System (INIS)

    This paper reports an experimental investigation of condensation heat transfer and pressure drop of an ozone friendly refrigerant, R-134a, inside a helical tube for climatic conditioning of hot regions. This study concerns the condensation of R-134a flowing through annular helical tubes with different operating refrigerant saturated temperatures. The average pressure drop is measured and compared with data from relevant literature. The measurements of R-134a were performed on mass flow flux ranges from 50 to 680 kg/m2 s. The study provides experimental data that could be used for the design and development of more efficient condensers for refrigeration and air conditioning (A/C) systems working with the same refrigerant

  20. Study on heat transfer performance of an aluminum flat plate heat pipe with fins in vapor chamber

    International Nuclear Information System (INIS)

    Highlights: • A novel flat plate heat pipe (FPHP) was designed and performed. • Maximum HS temperature is lower than 60 °C when the heat load reaches 100 W. • The FPHP will spend less time to start up with the increase of heat flux. • Liquid FR and VD have a significant influence on thermal performance of FPHP. - Abstract: The heat transfer performance of a novel flat plate heat pipe (FPHP) for electronic cooling was investigated experimentally. A variety of performance tests of FPHP were carried out with different air flow velocities (1.5 m/s < u < 6 m/s), working fluid filling ratios (10% < FR < 50%), and the vacuum degrees (0.002 Pa < VD < 0.25 Pa). Using distilled water and acetone as working fluids, the influence of the above parameters on steady-state heat transfer characteristics of the FPHP was also examined. The experimental results indicated that the filling ratio and vacuum degree had a significant influence on thermal performance of FPHP. Compared with cooling performance using distilled water and acetone, the FPHP cooling component using acetone had a stronger heat dissipation capacity for the same filling ratio

  1. Performance Evaluation of SG Tube Defect Size Estimation System in the Absence of Defect Type Classification

    International Nuclear Information System (INIS)

    In this paper, we study a new estimation system for the prediction of steam generator tube defects. In the previous research works, defect size estimators were independently designed for each defect types in order to estimate the defect size. As a result, the structure of estimation system is rather complex and the estimation performance gets worse if the classification performance is degraded for some reason. This paper studies a new estimation system that does not require the classification of defect types. Although the previous works are expected to achieve much better estimation performance than the proposed system since it uses the estimator specialized in each defect, the performance difference is not so large. Therefore, it is expected that the proposed estimator can be effectively used for the case where the defect type classification is imperfect

  2. Development and application of an efficient method for performing modal analysis of steam generator tubes in nuclear power plants

    International Nuclear Information System (INIS)

    A typical pressurized water reactor (PWR) steam generator has approximately 10,000 tubes. These tubes have different geometries, supporting conditions, and different material properties due to the non-uniform temperature distribution throughout the steam generator. Even though some tubes may have the same geometry and boundary conditions, the non-uniform distribution of coolant densities adjacent to the tubes causes them to have different added mass effects and dynamic characteristics. Therefore, for a reliable design of the steam generator, a separate modal analysis for each tube is necessary to perform the FIV (flow-induced vibration) analysis. However, the modal analysis of a tube including the finite element modeling is cumbersome and takes lots of time. And when a commercial finite element code is used, interfacing the modal analysis result, such as natural frequencies and mode shapes, with the FIV analysis procedure requires an additional significant amount of time and can possibly incur inadvertent error due to the complexity of data processing. It is therefore impossible to perform the complete FIV analysis for ten thousands of tubes when designing or maintaining a steam generator although it is necessary. Rather, to verify the safe design against the FIV, only a couple of tubes are chosen based on engineering judgment or past experience. In this paper, a computer program, PIAT-MODE, was developed which is able to perform modal analysis of all tubes of a PWR sorm modal analysis of all tubes of a PWR steam generator in a very efficient way. The geometries and boundary conditions of every tube were incorporated into PIAT-MODE using appropriate mathematical formulae. Material property data including the added mass effect was also included in the program. Once a specific tube is selected, the program automatically constructs the finite element model and generates the modal data very quickly. Therefore, modal analysis can be performed for every single tube in a straight way. When PIAT-MODE is coupled with the FIV analysis program, it gives an amazing benefit, which makes the FIV analysis of all tubes possible within a limited time during the design or maintenance period. Using the developed program, the stability ratio regarding the fluid-elastic instability and the amplitude of vibration resulting from the turbulence flow excitation can be calculated for all tubes according the standard ASME Code, therefore, much more reliable design of the steam generator against the FIV related failures can be achieved. For an operating plant, there is a requirement that every single tube must be quantitatively checked whether wear would be more than 40% in thickness during the next operation period. If yes, the tube must be plugged to prevent severe failure including the tube wall penetration. In order to decide the tube plugging, which leads the plant performance degradation, the wear prediction is required. The wear prediction analysis needs wear data by ultrasonic testing and modal property data of tubes. PIAT-MODE will be a power tool enabling the wear prediction in a limited maintenance period by supplying modal data for all tubes.

  3. Performance of horizontal U-tube type passive containment cooling system in a BWR

    International Nuclear Information System (INIS)

    To enhance countermeasures against important severe accident (SA) phenomena, SA mitigation systems with passive features are being developed to protect containment integrity and prevent release of a large amount of radioactive materials to environment after SA including core melt. Passive mitigation systems are preferable considering accident sequences with loss of power, which are dominant in Probabilistic Safety Assessment (PSA). The dedicated passive SA mitigation systems, i.e. passive containment cooling system (PCCS) combined with core catcher can be introduced to containment design of BWRs or Advanced BWRs (ABWRs) in the future. Heat removal capability of the PCCS has been verified through fundamental tests using single tube and full-scale bundle as well as its capability of non-condensable gases (NCG) purges from the tubes. An analysis models for the steam condensation inside of the tubes, boiling heat transfer outside of the tubes and two-phase flow pressure drop, including the degradation of steam condensation by the NCG, have been developed and validated. Furthermore, a system integral test for the PCCS performance has been conducted in order to demonstrate it using TIGER test facility. It showed good heat removal capability of the PCCS. MAAP code was applied to SA sequence analysis considering heat removal by the PCCS. The analysis showed that the PCCS combined with the core catcher could protect the integrity of the containment and avoid containment ventine containment and avoid containment venting in passive manner during SA. Although the passive heat removal models due to the steam condensation in the MAAP are not same as those developed by the PCCS tests, it was found that the MAAP models were more conservative. (authors)

  4. Effects of axial heat conduction, property variation and parasitic heat in-leak on performance of compact plate-fin heat exchangers

    International Nuclear Information System (INIS)

    Modern helium liquefaction/refrigeration systems employ compact plate-fin heat exchangers having very high effectiveness (>0.95). Performance of such systems is a strong function of effectiveness of heat exchangers used. The calculation of heat exchanger effectiveness in such cases needs considerations of several secondary parameters apart from basic fluid film resistance. In the present paper, the combined effects of secondary parameters like axial heat conduction through heat exchanger matrix and parasitic heat in-leak from the surroundings has been studied numerically. Large temperature changes in cryogenic heat exchangers may result in correspondingly larger changes in fluid properties and metal matrix conductivity, which shall be taken care of during numerical calculations. Numerical technique to solve the system of equations is implemented in MATLAB. Real properties of helium at each node are evaluated using HEPAK, which is linked to the developed code. Using this model, performance of heat exchangers is studied at four different temperature levels of (300-77)K, (77-20)K, (20-8)K and (10-5.1)K. The results highlight the effects of each of the above secondary parameters. (author)

  5. Plastic Guidance Fins for Long Rod Projectiles .

    Directory of Open Access Journals (Sweden)

    Mark L. Bundy

    1997-10-01

    Full Text Available Projectile tail fins on long rod kinetic energy (KE penetrators serve the same purpose as fletchings (feathers on an arrow, namely, they help align the projectile axis with its velocity vector. This reduces the projectile's yaw and hence reduces its aerodynamic drag. In addition, a low yaw angle at target impact helps to maximise the projectile's target penetration. It is typical for projectiles to exit the gun muzzle and enter free flight at some ndn-zero yaw angle. Aerodynamic forces acting on yawed tail fins create a stabilising torque about the projectile's centre of gravity (CG. This torque can be increased by making the fin material lighter. Most conventional long rod penetrators fired from high performance guns have tail fins made from aluminium. However, aluminium can undergo catastrophic oxidation (rapid burning in-bore. Coating aluminium with Al/sub 2/O/sub 3/ {hardcoat prevents ignition of the substrate, provided solid propellant grain impacts do not chip the brittle hardcoat off the surface. Plastic is lighter than aluminium and less exothermic when oxidized. Therefore, other factors aside, it is conceivable that plastic fins could increase projectile stability while incurring less thermal erosion than aluminium. However, thermal loads are not the only concern when considering plastic as an alternative tail fin material. The mechanical strength of plastic is also a critical factor. This paper discusses some of the successes and failures of plastic fins, at least relatively thin fins, for use as KE stabilisers.

  6. Comparative study of photocatalytic performance on different TiO2 nano-tubes arrays

    International Nuclear Information System (INIS)

    Highlights: • Two different TiO2 nano-tubes arrays were fabricated through anodic oxidization. • Different electrolytes could result in different nano-tubes with morphology. • The relationship between morphology and activity of TNTAs was investigated. • TNTAs-NH4F exhibited higher OCP, photovoltage and photo-convention efficiency. • Highly ordered structure favors the separation of photoinduced charge carriers. -- Abstract: Two different TiO2 nano-tubes arrays (TNTAs) have been successfully fabricated through constant potential anodic oxidization method, followed with post-annealing treatment. Morphologies and crystal structures of the as-fabricated TNTAs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that both TNTAs were comprised of anatase and rutile phase, while TNTAs-NH4F exhibited highly ordered nano-tubular structure. In addition, their photoelectrochemical (PECH) properties were investigated through open circuit potential (OCP) and photocurrent response. As a result, TNTAs-NH4F performed higher OCP (0.16 mA cm?2), photovoltage (0.1897 V cm?2) and photo-convention efficiency (0.18%) than that of TNTAs-NaF which could result in the more effective separation and transfer of photoinduced electrons and holes. Furthermore, the analysis of photocatalytic (PC) performance and output of hydroxyl radicals (·OH) demonstrated that TNTAs-NH4F photoanode possessed higher PC activity than that of TNTAs-NaF for photodegradation of methyl blue (MB). The higher PECH and PC performance could be ascribed to the highly ordered nano-tubular structure and higher separation and transfer efficiency of photoinduced charge carriers

  7. Research on the Pin Fin Efficiency and Structure

    OpenAIRE

    Fan Bailin; Huang Ganghan; Xu Long; Wang Yanjun; Zhang Pei

    2013-01-01

    The performance of pin fin heat sink can be to measure through the temperature field. The temperature field and efficiency of the Pin Fin were analyzed, Pin fin efficiency curve was drowned also the distribution of the temperature field along the length of the pin fin curve was drawn. Thermal resistance was composed by thermal resistance of Aluminum substrate? thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid. The change rule was studied through t...

  8. Study on the manufacturing process, causes of the pressure tube failure and methods for improving its performance

    International Nuclear Information System (INIS)

    Manufacturing processes of Zr-2.5Nb pressure tube used in CANDU reactor, effects of impurities on the properties of the pressure tube, experiences and causes of the pressure tube cracking accident and the development programs on the fuel channel at AECL have been described. Fabrication processes on the pressure tube have been explained in detail from the sponge production step to the final product. Test methods that are performed to verify the integrity of the final product have also been described. Most of the pressure tube rupture accidents were caused by DHC (Delayed Hydride Cracking). In cases of Pickering units 3 and 4 and Bruce unit 2, excessive residual stresses induced by improper rolled joint process had played a role to cause DHC. In Pickering unit 2, cracks formed by contact between pressure and calandria tubes due to the movement of garter spring were direct cause of failure. After the accidents, a lot of R and D programs on each component of the fuel channel have been carried out. The study on the improvement of manufacturing processes such as increasing cold working rate, performing the intermediate and final annealing and adding the third element like Fe, V, Cr for enhancing the pressure tube performance are on progress. To suppress hydrogen uptake into the pressure tube, the methods such as zirconia coating on the pressure tube, Cr-plating on the end fitting and placing the yttrium getter on the pressure tube are considered. Experiments on each test specimen are currently under way. Owing to such an effort, more advanced fuel channel can be installed in the next CANDU reactor. 6 tabs., 20 figs., 20 refs. (Author)

  9. Electronic imaging system using a high-performance HARPICON tube for neutron radiography

    International Nuclear Information System (INIS)

    A high-performance HARPICON tube has been equipped to an electronic imaging camera of Musashi Image Processing System for neutron radiography (NRG). A vertical limiting resolution of 1600 TV lines was obtained with an imaging size of 2048 x 2048 pixels using the EIAJ test chart-A. The camera was applied to neutron radiography at the NRG facility of JRR-3M at Japan Atomic Energy Research Institute and excellent neutron radiographs have been obtained. Durability of the HARPICON camera against neutron and gamma rays was proved. (orig.)

  10. Muscle activity during knee-extension strengthening exercise performed with elastic tubing and isotonic resistance

    DEFF Research Database (Denmark)

    Jakobsen, Markus Due; Sundstrup, Emil

    2012-01-01

    BACKGROUND/PURPOSE: While elastic resistance training, targeting the upper body is effective for strength training, the effect of elastic resistance training on lower body muscle activity remains questionable. The purpose of this study was to evaluate the EMG-angle relationship of the quadriceps muscle during 10-RM knee-extensions performed with elastic tubing and an isotonic strength training machine. METHODS: 7 women and 9 men aged 28-67 years (mean age 44 and 41 years, respectively) participated. Electromyographic (EMG) activity was recorded in 10 muscles during the concentric and eccentric contraction phase of a knee extension exercise performed with elastic tubing and in training machine and normalized to maximal voluntary isometric contraction (MVC) EMG (nEMG). Knee joint angle was measured during the exercises using electronic inclinometers (range of motion 0-90°). RESULTS: When comparing the machine and elastic resistance exercises there were no significant differences in peak EMG of the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM) during the concentric contraction phase. However, during the eccentric phase, peak EMG was significantly higher (p70% nEMG) quadriceps muscle activity during the concentric contraction phase, but slightly lower during the eccentric contraction phase, as knee extensions performed using an isotonic trainingmachine. During the concentric contraction phase the two different conditions displayed reciprocal EMG-angle patterns during the range of motion. LEVEL OF EVIDENCE: 5.

  11. Thermal performance of capillary micro tubes integrated into the sandwich element made of concrete

    DEFF Research Database (Denmark)

    Mikeska, Tomas; Svendsen, Svend

    2013-01-01

    The thermal performance of radiant heating and cooling systems (RHCS) composed of capillary micro tubes (CMT) integrated into the inner plate of sandwich elements made of High Performance Concrete (HPC) was investigated in the article. Temperature distribution in HPC elements around integrated CMT was studied. Thermal heat flux on the inner surface of HPC element was carefully investigated. Calculations were carried out for different temperatures of the circulating fluid, different spacing between CMT and different thicknesses of the inner HPC layer covering the CMT. This paper shows that CMT integrated into the thin plate of sandwich element made of HPC can supply the energy needed for heating and cooling. The investigations were conceived as a low temperature concept, where the difference between the temperature of circulating fluid and air in the room was kept in range of 1 to 4°C. © (2013) Trans Tech Publications, Switzerland.

  12. QuantiFERON-TB Gold In-Tube test performance in Denmark

    DEFF Research Database (Denmark)

    Hermansen, Thomas; Lillebaek, Troels

    2014-01-01

    BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tuberculosis (TB). METHODS: A retrospective study analysing the results of 18,850 QFT performed in Denmark 2005-2010. The effect of age, sex, localisation of TB, and result of culture on QFT performance (positive, negative and indeterminate results) was determined. RESULTS: Among 383 patients with TB, indeterminate rate was low (3.9%, 15/383). Sensitivity was high (86.1%, 317/368) and not affected by sex or localization of TB disease, but declined with increasing age (p 65 years (8.1%, 219/2715) compared tothe adult population 15-64 years (4.5%, 552/12,317). Indeterminate results were due to a low positive control in 99.6% (801/804). CONCLUSION: In Denmark, a TB low incidence country, the overall QFT performance was good. The sensitivity in children (?1) was high although few children were included, whereas sensitivity declined with increasing age. Indeterminate rates were higher in infants and elderly. In contrast to current guidelines, our data suggest that the QFT performs well in children ?1 years in low endemic regions but that the test should be used with care among the elderly.

  13. QuantiFERON–TB Gold In-Tube test performance in Denmark

    DEFF Research Database (Denmark)

    Hermansen, Thomas; Lillebaek, Troels

    2014-01-01

    BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tuberculosis (TB). METHODS: A retrospective study analysing the results of 18,850 QFT performed in Denmark 2005-2010. The effect of age, sex, localisation of TB, and result of culture on QFT performance (positive, negative and indeterminate results) was determined. RESULTS: Among 383 patients with TB, indeterminate rate was low (3.9%, 15/383). Sensitivity was high (86.1%, 317/368) and not affected by sex or localization of TB disease, but declined with increasing age (p 65 years (8.1%, 219/2715) compared tothe adult population 15-64 years (4.5%, 552/12,317). Indeterminate results were due to a low positive control in 99.6% (801/804). CONCLUSION: In Denmark, a TB low incidence country, the overall QFT performance was good. The sensitivity in children (? 1) was high although few children were included, whereas sensitivity declined with increasing age. Indeterminate rates were higher in infants and elderly. In contrast to current guidelines, our data suggest that the QFT performs well in children ? 1 years in low endemic regions but that the test should be used with care among the elderly.

  14. Experimental Evaluation of the Energy Performance of an Air Vortex Tube when the Inlet Parameters are Varied

    OpenAIRE

    Torrella Alcaraz, Enrique; Patiño Pérez, Jorge; Sánchez García-Vacas, Daniel; LLOPIS DOMÉNECH, RODRIGO; Cabello López, Ramón

    2013-01-01

    he paper presents the analysis of the energy performance of an air vortex cooling tube under variations of the air inlet properties, with t hree independent experimental tests validated through the energy balance in the device. The experimental analysis includes the following variations of the input conditions: First, the effect of the air inlet pressure to the vortex tube, focused on the analysis of temperature variations in the output cold stream and in the coo...

  15. Exergy Flow in Pulse Tube Refrigerators and Their Performance Evaluation Based on Exergy Analysis

    Science.gov (United States)

    Razani, A.; Flake, B.; Yarbrough, S.

    2004-06-01

    Exergy flow in Orifice Pulse Tube Refrigerators (OPTR) is investigated. Input power to the compressor provides the source of exergy and the input exergy's magnitude diminishes as working fluid passes through each component. The exergy destruction is due to the irreversibility of each component in the refrigerator. The only product of the system is the exergy associated with the refrigeration power. It is shown that for an ideal OPTR, where the orifice is the only source of irreversibility, the exergy destruction is equivalent to the refrigeration power resulting in a second law efficiency of (Th - Tc)/ Th for the system. A model for the effect of different system parameters on the irreversibility of the compressor, regenerator, and orifice is developed and exergy flow in the system is analyzed. A proper definition of the second law efficiency for each component is given and it is shown that exergy analysis is a powerful method for understanding the mechanism, performance evaluation, design, and optimization of the pulse tube refrigerator.

  16. Measurement of the performance of a spiral wound polyimide regenerator in a pulse tube refrigerator

    Science.gov (United States)

    Rawlins, Wayne; Timmerhaus, Klaus D.; Radebaugh, Ray; Daney, D. E.

    1991-01-01

    A regenerator for use in a pulse tube refrigerator has been constructed from a polyimide (polypyromellitimide or PPMI) whose small ratio of thermal conductivity to heat capacity make it a good candidate for a regenerator material in cryocoolers. The regenerator was fabricated using 25 micron thick photoresist strips bonded to a 50 micron thick sheet of PPMI. This composite sheet was wound in jelly-roll fashion around a mandrel and inserted into the regenerator housing. The photoresist strips, formed using a photolithographic technique, provided a 25 micron spacing for the axial flow of gas between each layer of PPMI. Ineffectiveness results are presented for this material under actual operating conditions in a pulse tube refrigerator and compared with a numerical model. The numerical model indicated that a polyimide regenerator would perform much better than one constructed of stainless steel screen, but the experimental results showed the opposite behavior. Measured values for the ineffectiveness were 0.003 for the stainless steel screen and 0.017 for the polyimide.

  17. Study on the effect of punched holes on flow structure and heat transfer of the plain fin with multi-row delta winglets

    Science.gov (United States)

    Tian, Liting; Liu, Bin; Min, Chunhua; Wang, Jin; He, Yaling

    2015-02-01

    Three dimensional numerical simulations are performed to investigate the flow and heat transfer characteristics of the plain fin with multi-row delta winglets punched out from the fin. The Reynolds number based on the tube outside diameter varies from 360 to 1440. The effects of punched holes and their orientations on flow structure and heat transfer are numerically studied. Results show that a down-wash flow is formed through the hole punched at the windward side, which has little influence on the longitudinal vortices in the main flow, and a longitudinal main vortex is formed behind each delta winglet. An up-wash flow is formed through the hole punched at the leeward side, the up-wash flow impinges the longitudinal vortices generated by the delta winglet, and then a counter-rotating pair of main vortices is generated behind each delta winglet. The windward punched holes have little effect on the flow friction and heat transfer of the plain fin with delta winglets, while the leeward punched holes deteriorate the heat transfer and decrease the flow friction of the fin channel, the Nusselt number decreases by 3.5-5.0 % with a corresponding decrease of 3.9-4.8 % in the friction factor. The effect of the punched holes on the heat transfer of the fin can be well explained by the field synergy principle. The overall analysis of the thermal performance is performed for all fin configurations, including the slit fins and the wavy fins with one-row delta winglets, the plain fin with the windward punched delta winglets shows the better thermal performance than one with the leeward punched delta winglets.

  18. THERMAL ANALYSIS OF CPU WITH COMPOSITE PIN FIN HEAT SINKS

    Directory of Open Access Journals (Sweden)

    R.Mohan

    2010-09-01

    Full Text Available This paper describes about pin fin and slot parallel plate heat sinks with copper and carbon carbon composite(CCC base plate material mounted on CPU’s. The parameters such as fin geometry, base plate material, base plate thickness, number of fins, fin thickness are considered and primarily in this paper fin geometry, base platethicknesses, base plate materials are optimized for improving the thermal performance of a heat sink in the next generation. In this research work, the thermal model of the computer system with various fin geometry heat sink design has been selected and the fluid flow, thermal flow characteristics of heat sinks have been studied. The plate, pin and Elliptical fin geometry heat sinks have been used with base plate to enhance the heat dissipation. In this study a complete computer chassis with different heat sinks are investigated and the performances of the heat sinks are compared.

  19. Experimental Performance of Window Air Conditioner Using Alternative Refrigerants with Different Configurations of Capillary Tube: A Review

    Directory of Open Access Journals (Sweden)

    Richa Soni

    2013-08-01

    Full Text Available This review paper presents the work of various researches on the performance of capillary tube ,used in air conditioners with various refrigerants. Research carried out by different authors uses different type of capillary tubes (straight, twisted, coiled in different length and diameter. they determined various parameters like coefficient of performance (COP,cooling capacity, energy efficiency ratio (EER of the system. Various approaches have been used by different authors to predict the performance of capillary in window air conditioner using alternative refrigerant as capillary expansion device.

  20. Lightweight Radiator Fins for Space Nuclear Power Project

    National Aeronautics and Space Administration — This SBIR Phase 1 project shall investigate concept radiator fins that incorporate novel carbon materials for improved performance of segmented high temperature...

  1. Enhancement of ECR performances by means of carbon nano-tubes based electron guns

    International Nuclear Information System (INIS)

    The CANTES experiment at INFN-LNS tested the use of carbon nano-tubes (CNTs) to emit electrons by field emission effect, in order to provide additional electrons to the plasma core of an ECR ion source. This technique was used with the Caesar source, demonstrating that the total extracted ion current is increased and that a relevant reduction of the number of 'high energy' electrons (above 100 keV) may be observed. The injection of additional electrons inside the plasma increases the amount of cold and warm electrons, and then the number of ionizing collisions. Details of the construction of CNTs based electron gun and of the improvement of performances of the Caesar ECR ion source will be presented. The paper is followed by the associated poster. (authors)

  2. Performance of the MACRO limited streamer tubes for estimates of muon energy

    CERN Document Server

    Giorgini, M

    2002-01-01

    The MACRO limited streamer tubes can be operated in drift mode by using the TDCs included in the QTP system. In this way a considerable improvement in the space resolution is obtained, allowing the analysis of muon tracks in terms of multiple scattering effects and the energy estimates of muons crossing the detector. We present the results of two dedicated tests, performed with the CERN PS-T9 and SPS-X7 beams, to provide a full check of the electronics and to exploit the feasibility of the analysis. Using a neural network, we are able to estimate the muon energies up to E/sub mu / approximately = 40 GeV. The test beam data provide then an absolute energy calibration, which allows to apply the method to the MACRO data. (5 refs).

  3. Study on a Concentric Tube Bulb Manometer and its Performance Compared to U-shaped Manometer

    Directory of Open Access Journals (Sweden)

    Muhammad A. Butt

    2007-11-01

    Full Text Available This paper presents comparative study of a new type of manometer calledconcentric tube bulb (C.T.B manometer. Its performance of measuring differential heightis studied against conventional U-shaped manometer. Pressure drops and mass flow ratesare calculated by taking various systems comprising of different flow measuring devicessuch as orifice and venturimeters using both U- shaped and C.T.B manometers.Comparison between the physically measured values of differential pressure drops andmass flow rates with the calculated values based on theoretical equations is also made.Experiments are carried out using mercury and CCl4 in these manometers as sensing fluids.Water is used as flowing fluid for mass flow rate and pressure drop measurements, whereasin gauge pressure measurements air is used.

  4. Hydrodynamics and heat transfer in channels with circular fins

    International Nuclear Information System (INIS)

    The numerical analysis of the task on the hydrodynamics and heat exchange by the stationary completely developed flow of the viscous incompressible liquid in the circular tube with the internal annular fins is carried out. The numerical model is plotted for calculating the laminar flows with constant efficiency, used for pumping. The results of the studies on the fins height and their number effect on the hydraulic characteristics and heat exchange in the channel are presented

  5. Performance comparison between three intraoral image receptors of different technology at a variety of tube potential, tube current and exposure time settings using a stepwedge phantom

    Directory of Open Access Journals (Sweden)

    Elli Katsoni

    2011-01-01

    Full Text Available Purpose: To comparatively evaluate the per-formance of three intraoral image receptors of different technology when exposed to different X-ray beam spectra, dose and dose rate levels using a stepwedge phantom. Materials and methods: The intraoral radiographic receptors evaluated were: the Kodak Insight F speed class film, the Kodak RVG 6000, and the Duerr Vis-tascan Combi PSP system. A dental quality control phantom made of Plexiglas, containing an aluminium stepwedge with 12 steps and 7 holes drilled in each step was radiographed using a dental X-ray unit offering a wide range of tube potential, tube current and exposure time settings. The visibility of the holes in the images produced with each one of the three receptors was assessed by three independent observers. For each image the total image quality score (TS was derived from the summation of the number of visible holes in each step. The numbers of perceptible holes in each experimental condition (TSs were statistically analyzed through use of analysis of variance. Intraobserver and interobserver agree-ment was also measured. Results: Vistascan ex-hibited the most extended useful exposure range, followed by RVG 6000 and Insight. RVG 6000 exhibited the largest TS values in all tube potential settings except 70 kV where the Vistascan performed better. Insight performed better than Vistascan only at 60 and 63 kV. Vistascan performed better at 66 and 70 kV, Insight at 60 and 66 kV, whereas RVG performed equally well at all tube potential settings, except than at 52 and 70 kV. For the Insight the largest TS values were obtained with the smallest ESAK values whereas with the Vistascan the largest TS were obtained with ESAK values that where the largest observed. Conclusions: The performance of all receptors tested was greatly dependent on the exposure parameters and mainly on the kV settings. Overall, the RVG 6000 offered the best image quality at doses somewhere in between those required by the Insight and the Vistascan.

  6. Shock tube investigation of dynamic response of pressure transducers for validation of rotor performance measurements

    Science.gov (United States)

    Bershader, Daniel

    1988-01-01

    For some time now, NASA has had a program under way to aid in the validation of rotor performance and acoustics codes associated with the UH-60 rotary-wing aircraft; and to correlate results of such studies with those obtained from investigations of other selected aircraft rotor performance. A central feature of these studies concerns the dynamic measurement of surface pressure at various locations up to frequencies of 25 KHz. For this purpose, fast-response gauges of the Kulite type are employed. The latter need to be buried in the rotor; they record surface pressures which are transmitted by a pipette connected to the gauge. The other end of the pipette is cut flush with the surface. In certain locations, the pipette configuration includes a rather sharp right-angle bend. The natural question has arisen in this connection: In what way are the pipettes modifying the signals received at the rotor surface and subsequently transmitted to the sensitive Kulite transducer element. The basic details and results of the program performed and recently completed in the High Pressure Shock Tube Laboratory of the Department of Aeronautics and Astronautics at Stanford University are given.

  7. Photomultiplier tube detector performance and stability for the Earth Observing System's SOLSTICE II instrument

    Science.gov (United States)

    Drake, Virginia A.; McClintock, William E.; Kohnert, Richard A.; Woods, Thomas N.; Rottman, Gary J.

    2000-12-01

    The goal of the Earth Observing System (EOS) SOLar STellar Irradiance Comparison Experiment II (SOLSTICE II) is to measure the solar ultraviolet irradiance (115 nm - 320 nm) to within 5% of its absolute value with a 0.5% per year relative accuracy over the course of a minimum mission lifetime of five years. Most detectors degrade over time while studying the sun. The SOLSTICE instrument design is such that detector and optical system degradation is tracked by routinely observing a series of stable early-type stars. Any changes in the system may then be removed from the solar irradiance. Detector performance and stability lies at the heart of SOLSTICE experimental success. The SOLSTICE detectors are Hamamatsu R2078 PhotoMultiplier Tubes (PMTs). We have developed an integrated PMT package [PMT, PMT housing, (mu) -metal magnetic shield, high voltage divider, and pulse-amplifier discriminator (PAD)] that will achieve our performance objectives. We report here on both the design of the integrated detector package and the laboratory measurements of the operational lifetime performance characteristics of SOLSTICE detectors. These include pulse height distribution, quantum efficiency, photocathode surface uniformity, and magnetic susceptibility.

  8. Performance of Subsurface Tube Drainage System in Saline Soils: A Case Study

    Science.gov (United States)

    Pali, A. K.

    2015-06-01

    In order to improve the saline and water logged soils caused due to groundwater table rise, installation of subsurface drainage system is considered as one of the best remedies. However, the design of the drainage system has to be accurate so that the field performance results conform to the designed results. In this investigation, the field performance of subsurface tube drainage system installed at the study area was evaluated. The performance was evaluated on the basis of comparison of the designed value of water table drop as 30 cm after 2 days of drainage and predicted and field measured hydraulic heads for a consecutive drainage period of 14 days. The investigation revealed that the actual drop of water table after 2 days of drainage was 25 cm, about 17 % less than the designed value of 30 cm after 2 days of drainage. The comparison of hydraulic heads predicted by Van Schilfgaarde equation of unsteady drainage with the field-measured hydraulic heads showed that the deviation of predicted hydraulic heads varied within a range of ±8 % indicating high acceptability of Van Schlifgaarde equation for designing subsurface drainage system in saline and water logged soils resembling to that of the study area.

  9. A study on heat transfer enhancement using straight and twisted internal fin inserts

    International Nuclear Information System (INIS)

    The present study investigated the effect of internal aluminum fins with a star shape cross section on the heat transfer enhancement and pressure drop in a counterflow heat exchanger. A concentric tube heat exchanger was used with water as the working fluid. The heat transfer rate increased by 12-51% over the plain tube value, depending on the internal fin configuration used. However, the pressure drop also increased substantially by an average of 286-338%. The results showed that a straight fin configuration is good enough to produce a heat transfer increase in a counterflow heat exchanger. Twisted fin configurations did not further increase the heat transfer rate

  10. Pollen performance before and during the autotrophic-heterotrophic transition of pollen tube growth.

    OpenAIRE

    Stephenson, Andrew G.; Travers, Steven E.; Mena-ali, Jorge I.; Winsor, James A.

    2003-01-01

    For species with bicellular pollen, the attrition of pollen tubes is often greatest where the style narrows at the transition between stigmatic tissue and the transmitting tissue of the style. In this region, the tubes switch from predominantly autotrophic to predominantly heterotrophic growth, the generative cell divides, the first callose plugs are produced, and, in species with RNase-type self-incompatibility (SI), incompatible tubes are arrested. We review the literature and present new f...

  11. An apparatus for the measurement of regenerator performance in pulse tube refrigerators

    Science.gov (United States)

    Rawlins, Wayne; Radebaugh, Ray

    1990-01-01

    This paper discusses the design and construction of an apparatus to measure the ineffectiveness of regenerators used for pulse tube refrigerators. Because of the fairly large mass flow rates which occur in pulse tube refrigerators, the regenerator ineffectiveness must be made quite small. The apparatus described here allows for the measurement of the refrigerator. A low temperature heat sink of liquid nitrogen is used since it approximates the temperatures normally achieved in a one-stage pulse tube.

  12. An apparatus for the measurement of regenerator performance in pulse tube refrigerators

    International Nuclear Information System (INIS)

    This paper discusses the design and construction of an apparatus to measure the ineffectiveness of regenerators used for pulse tube refrigerators. Because of the fairly large mass flow rates which occur in pulse tube refrigerators, the regenerator ineffectiveness must be made quite small. The apparatus described here allows for the measurement of the refrigerator. A low temperature heat sink of liquid nitrogen is used since it approximates the temperatures normally achieved in a one-stage pulse tube. 10 refs

  13. An approach to optimal fin diameter based on entropy minimization

    Directory of Open Access Journals (Sweden)

    Masoud Asadi

    2013-04-01

    Full Text Available Pin fin geometries provide a large surface area of heat transfer and reduce the thermal resistance of the package. One of the important features of this type of fins is that they often take less space and contribute less to the weight and cost of the product. Pin fin arrays are used widely in many applications such as gas turbine or electronic circuits cooling, where pin fin geometries use due to their low cost of manufacturing and easy installing. In gas turbine application heat transfer from the blade to the coolant air can be increased by installing pin fins. In fact, Pin fin arrays increase heat transfer by increasing the flow turbulence and surface area of the airfoil exposed to the coolant. The overall performance of a heat exchanger with pin-fin typically depends on a number of parameters including the fin diameter, dimensions of the baseplate and pin-fins, thermal joint resistance and location heat sources. These parameters have an impact on the optimal design of a heat exchanger. Fin diameter is a key parameter to determine overall heat exchanger efficiency and entropy generation. In this paper, our objective is introducing an Equation to calculate optimal fin diameter based on minimizing entropy generation.

  14. Cooling performance assessment of horizontal earth tube system and effect on planting in tropical greenhouse

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The cooling ability of HETS is studied for planting in tropical greenhouse. • The effective of system was moderate with COP more than 2.0. • Increasing diameter and air velocity increase COP more than other parameters. • The plant growth with HETS was significantly better than no-HETS plant. - Abstract: The benefit of geothermal energy is used by the horizontal earth tube system (HETS); which is not prevalent in tropical climate. This study evaluated geothermal cooling ability and parameters studied in Thailand by mathematical model. The measurement of the effect on plant cultivation was carried out in two identical greenhouses with 30 m2 of greenhouse volume. The HETS supplied cooled air to the model greenhouse (MGH), and the plant growth results were compared to the growth results of a conventional greenhouse (CGH). The prediction demonstrated that the coefficient of performance (COP) in clear sky day would be more than 2.0 while in the experiment it was found to be moderately lower. The parameters study could be useful for implementation of a system for maximum performance. Two plants Dahlias and head lettuce were grown satisfactory. The qualities of the plants with the HETS were better than the non-cooled plants. In addition, the quality of production was affected by variations of microclimate in the greenhouses and solar intensity throughout the cultivation period

  15. Diagnostic performance of liquid crystal and cathode-ray-tube monitors in brain computed tomography

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate feasibility of reporting brain CT examinations on liquid crystal display (LCD) flat-screen monitors vs state-of-the-art cathode-ray-tube (CRT) monitors. Ninety-five brain CT examinations of 95 patients were displayed on Picture archiving and communications system (PACS) workstations equipped either with a dedicated medical imaging LCD colour monitor or on a high-resolution CRT which is used for routine reporting of CT, MRI and digital radiography images in our institution. Fifty cases were negative and 45 cases were positive for early brain infarction (EBI), the latter being defined by a combination of one or more signs: dense artery; hypodensity of brain parenchyma; and local brain swelling verified by control scans. Ten radiologists had to rate presence or absence of EBI on a five-point scale. Ratings were evaluated by CORROC2 ROC software and areas under the ROC curve (Az) were computed. Significance of differences between the two viewing conditions were evaluated with Wilcoxon test. Mean Az of the ten observers was 0.7901 with LCD vs 0.7695 with CRT which did not show statistical significance (p=0.2030). In the setting investigated, reporting of CT studies from high-performance LCD monitors seems feasible without significant detriment to diagnostic performance. (orig.)

  16. Performance of a split-type air conditioner matched with coiled adiabatic capillary tubes using HCFC22 and HC290

    International Nuclear Information System (INIS)

    This paper experimentally investigated the system performance of a split-type air conditioner matching with different coiled adiabatic capillary tubes for HCFC22 and HC290. Experiments were carried out in a room-type calorimeter. The results have shown that (1) similar cooling effects can be achieved by matching various capillary tubes of different inner diameters; (2) parallel capillary tubes presented better system performance and flow stability with weaker inlet pressure fluctuations than the single capillary tube; (3) with the coil diameter of the capillary tube increasing from 40 mm to 120 mm, the mass flow rate tended to increase slightly. But the cooling capacity, input power and energy efficiency ratio (EER) did not show evident tendency of change; (4) the refrigerant charge and mass flow rate for HC290 were only 44% and 47% of that for HCFC22, respectively, due to the much lower density. And HC290 had 4.7-6.7% lower cooling capacity and 12.1-12.3% lower input power with respect to HCFC22. However, the EER of HC290 can be 8.5% higher than that of HCFC22, which exhibits the advantage of using HC290. In addition, the experimental uncertainties were analyzed and some application concerns of HC290 were discussed.

  17. Measurement of Work Generation and Improvement in Performance of a Pulse Tube Engine

    Science.gov (United States)

    Hamaguchi, Kazuhiro; Futagi, Hiroaki; Yazaki, Taichi; Hiratsuka, Yoshikatsu

    Apart from double acting type engines, Stirling engines have either 2 pistons in 2 cylinders or 2 pistons in a single cylinder. Typically, the heater, regenerator and cooler are installed between the 2 pistons. The pulse tube engine, on the other hand, consists of a single piston in a single cylinder, a pulse tube, a heater, a regenerator, a cooler and a second cooler. For this paper, a simple prototype engine that uses air at normal atmospheric pressure as the working gas was fabricated. The oscillating velocity of the working gas in the pulse tube was measured using LDV, and the work flow emitting out of the pulse tube was observed. In addition, the effect of inserting heat storage material in the pulse tube on shaft power and indicated power was examined experimentally. A dramatic increase in the shaft power was achieved.

  18. Benchmarking the Performance of the ANSYS-FLUENT Standard k- ? Turbulence Model in Fluid Flow and Heat Transfer Predictions for Complex Flows around Circular Pin-Fins Using Various near Wall Functions

    Directory of Open Access Journals (Sweden)

    A. Al-Witry

    2013-05-01

    Full Text Available This study compares CFD analyses of the fluid flow and heat transfer phenomena in a popular pin-fin geometry of X/D = 2.5, S/D = 2.5 and H/D = 1 for a range of Re = 5,000 to 30,000 to those from experiment to aid in the benchmarking the performance of the CFD code FLUENT. The CFD analyses use three ANSYS-FLUENT (version 13 near wall treatments available within the code: 1 the Standard Wall Function (SWF, 2 the Non-Equilibrium Wall Function (NEWF and 3 the enhanced wall treatment. Experimental data used in this study were obtained from two papers: 1 by Chyu et al. (1998 for heat transfer predictions and another 2 by Metzgeret al. (1984 for pressure loss predictions, both for the same setup. The study also differentiates between the heat transfer occurring by the body of the pin-fin itself and that by the end-wall areas surrounding it. Results from the CFD analyses based on the fourth pin-fin from the inlet (commonly assumed to have a stable flow around it, show very good prediction accuracies of heat transfer coefficients for the pin-fin body itself but rather low accuracies for the end-wall areas (based on heat flux and inlet temperature values. Better accuracies were obtained when using the enhanced wall treatment where pin-fin body heat transfer coefficients were almost identical between the CFD and experimental results. An alternative definition of heat transfer based on the averaged local temperatures around the fourth pin-fin showed that the heat transfer coefficient then (with CFD's capability to establish the local thermal field is really between 1.5 to 3.5 times that predicted by using the inlet temperature in deducing the local h values. The same accuracies cannot be said about its predictions of pressure loss coefficients where CFD results tended to be lower by 50-100%h.

  19. Performance Evaluation of a Forced Convection Solar Drier with Evacuated Tube Collector for Drying Amla

    Directory of Open Access Journals (Sweden)

    AR. Umayal Sundari

    2013-06-01

    Full Text Available A forced convection solar drier is designed with evacuated tube collector and a blower. The performance of the designed drier is evaluated by carrying drying experiments at Thanjavur District, Tamilnadu, India with amla. Solar drying of amla is carried at different air velocity flow rates – 4m/s, 4.25m/s and 4.5m/s and is compared with natural sun drying. The temperature of the dryingchamber ranges from 53ºC to 82ºC while the ambient temperature ranges from 29ºC to 32ºC. The efficiency of the designed drier varies from 38.61% to 43.7% where as the efficiency of sun drying varies from 12.5% to 14.15%. It is observed that the efficiency of the drier increases with increase in air velocity flow rates. Initial moisture content of amla ranges between 83.6% and 84.3% and the equilibrium moisture content ranges between 0.1% and 0.6%. Solar drying takes 5 to 7 hours to reach safe moisture content where as sun drying takes 13 to15 hours. Also the quality of solar dried amla is better in terms of colour, odour, flavour and appearance than the sun dried amla. The observed result of the present work shows that the proposed solar drier is good for drying amla in this region.

  20. The effect of elastic modulus and friction coefficient on rubber tube sealing performance

    Science.gov (United States)

    Li, Zhimiao; Xu, Siyuan; Ren, Fushen; Liu, Jubao

    2015-03-01

    The packer is the key element in separating geosphere layers of water injection, water plugging and fracturing operations in the oilfield. The sealing ability of the packer is depending on the contact pressure between rubber tube and the casing. The circumferential strain of casing wall was tested by the strain gauge to get the contact pressure distribution along axial direction of the tube. The friction force between the casing and the rubber tube was taken by the pressure sensor in compression process. Under the 20,60 and 100 degrees Celsius conditions, the friction forces and the contact pressure distribution were taken in work condition of single rubber tube, double rubber tubes and combination rubber tubes after oil immersion .The result shows that elastic modulus of rubber tube has little effect on the friction force and contact pressure. With elastic modulus decreasing, the friction forces has gradually decreasing trend; The friction coefficient has much impact on friction force: the friction forces under the condition of dry friction and wet friction are respectively equivalent to 48.27% and 5.38% axial compression forces. At wet friction condition, the contact pressure distribution is more uniform and the sealing effect is better.

  1. EXPERIMENTAL HEAT TRANSFER ANALYSIS ON ANNULAR CIRCULAR AND ELLIPTICAL FINS .

    OpenAIRE

    N.Nagarani,; Mayilsamy, K.

    2010-01-01

    Most of the engineering problems require high performance heat transfer components with progressively less weights, volumes, accommodating shapes and costs. Extended surfaces (fins) are one of the heat exchanging devices that are employed extensively to increase heat transfer rates. The rate of heat transfer depends on the surfacearea of the fin. Radial or annular fins are one of the most popular choices for exchanging the heat transfer rate from the primary surface of cylindrical shape. In t...

  2. Study of the performance of ATLAS muon drift-tube chambers in magntic fields and at high irradiation rates

    Energy Technology Data Exchange (ETDEWEB)

    Valderanis, Chrysostomos

    2012-07-26

    The performance of ATLAS muon drift-tube (MDT) chambers has been studied in detail using high-energy muon beams. The measurements of the drift tube properties in magnetic fields showed that inelastic collisions of the drifting electrons with the CO{sub 2} molecules in the Ar:CO{sub 2} (93:7) gas mixture of the MDT chambers have to be taken into account in the simulation of the drift properties. Such inelastic collisions are now correctly treated by the Garfield simulation programme from version 9 providing an accurate description of the behaviour of the ATLAS muon drift tubes, in particular in the magnetic field. Measurements at the Gamma Irradiation Facility at CERN were performed to study the performance of the MDT chambers in the presence of high {gamma} ray background fluences. The chambers have a spatial resolution better than 40 {mu}m at the nominal background rates expected at the Large Hadron Collider design luminosity of 10{sup 34} cm{sup -2}s{sup -1} and a resolution better than 50 {mu}m for up to five times higher background rates. Efficient muon detection up to background counting rates of 500 kHz per tube corresponding to 35% occupancy was demonstrated.

  3. Estimation of heat transfer performance of surface condenser with titanium tubes

    International Nuclear Information System (INIS)

    The heat transfer characteristic of titanium tube expected for use for the condenser is described. Titanium is inferior in heat conductivity to copper alloys. But this problem is solved at the design level. Since contaminant adhesion to the tube is thought to differ from plant to plant, the cleaning condition must be worked out while the vacuum is observed. This report shows an example of sponge-ball cleaning test and investigates the effect of a sponge ball with carborundum on the wear of tubing material. The test results indicate that even when chlorination is not used, the ball cleaning is sufficient heat transfer measure. (author)

  4. Final Technical Report - High-Performance, Oxide-Dispersion-Strengthened Tubes for Production of Ethylene adn Other Industrial Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    McKimpson, Marvin G.

    2006-04-06

    This project was undertaken by Michigan Technological University and Special Metals Corporation to develop creep-resistant, coking-resistant oxide-dispersion-strengthened (ODS) tubes for use in industrial-scale ethylene pyrolysis and steam methane reforming operations. Ethylene pyrolysis tubes are exposed to some of the most severe service conditions for metallic materials found anywhere in the chemical process industries, including elevated temperatures, oxidizing atmospheres and high carbon potentials. During service, hard deposits of carbon (coke) build up on the inner wall of the tube, reducing heat transfer and restricting the flow of the hydrocarbon feedstocks. About every 20 to 60 days, the reactor must be taken off-line and decoked by burning out the accumulated carbon. This decoking costs on the order of $9 million per year per ethylene plant, accelerates tube degradation, and requires that tubes be replaced about every 5 years. The technology developed under this program seeks to reduce the energy and economic cost of coking by creating novel bimetallic tubes offering a combination of improved coking resistance, creep resistance and fabricability not available in current single-alloy tubes. The inner core of this tube consists of Incoloy(R) MA956, a commercial ferritic Fe-Cr-Al alloy offering a 50% reduction in coke buildup combined with improved carburization resistance. The outer sheath consists of a new material - oxide dispersion strengthened (ODS) Alloy 803(R) developed under the program. This new alloy retains the good fireside environmental resistance of Alloy 803, a commercial wrought alloy currently used for ethylene production, and provides an austenitic casing to alleviate the inherently-limited fabricability of the ferritic Incoloy(R) MA956 core. To provide mechanical compatibility between the two alloys and maximize creep resistance of the bimetallic tube, both the inner Incoloy(R) MA956 and the outer ODS Alloy 803 are oxide dispersion strengthened materials produced using mechanical alloying technology. To minimize cost, the bimetallic tube is produced by direct powder co-extrusion. This technology has potential for domestic energy savings of up to 4.1 trillion BTU/year (4.3 x 1015J/year) and a reduction of 370,000 tons (340,000 tonnes) of CO2 emissions in short-residence-time ethylene furnaces. This represents an energy savings and CO2 emissions reduction of about 3.3%. If the technology is also applied to other types of ethylene pyrolysis furnaces, total energy savings and CO2 emissions reductions could increase by up to five times. The work involved: Developing powder and consolidation processing protocols to produce an oxide-dispersion strengthened variant of Alloy 803 exhibiting creep strength comparable to Incoloy? Alloy MA956, Developing a direct powder co-extrusion protocol for fabricating co-extruded bimetallic Incoloy? Alloy MA956 / ODS Alloy 803 tubes, Characterizing the properties of the ODS Alloy 803 material, the welding characteristics of the bimetallic tubes, and the coking characteristics of the Incoloy? MA956 alloy, and Documenting the potential energy savings and user requirements for these bimetallic pyrolysis furnace tubes. The project demonstrated that oxide dispersion strengthened Alloy 803 can be produced successfully using conventional mechanical alloying technology. The oxide dispersion strengthened bimetallic radiant coil technology explored under this program has significant potential for energy savings and productivity improvements for domestic ethylene producers. In today's competitive market, however, domestic furnace manufacturers and ethylene producers appear reluctant to pay any cost premium for higher-performance coil materials offering either higher temperature capabilities or longer service life. Interest in oxide dispersion strengthened radiant coils is likely to increase if furnace and ethylene producers begin to focus more on increasing tube wall temperatures to improve productivity.

  5. Thermal performance of direct-flow coaxial evacuated-tube solar collectors with and without a heat shield

    International Nuclear Information System (INIS)

    Graphical abstract: Collection efficiency plots and linear characterization of evacuated tube solar collector with a heat shield (ETC-HS) and evacuated tube solar collector without a heat shield (ETC-NHS). - Highlights: • Evacuated solar collector (ETC) with a heat shield had better thermal performance. • Efficiency of ETC with a heat shield is 54.70% at inlet temperature 123.9 °C. • 31.49% higher than efficiency of ETC without a heat shield at this temperature. • Heat loss coefficients of ETC with a heat shield was 1.86 W/(m2 K). • A 50.80% improvement in heat loss reduced compared to ETC without a heat shield. - Abstract: Experimental performance evaluation and comparative analyses based on heat extraction of direct-flow coaxial evacuated-tube solar collectors with and without heat shields are presented in this paper. A test system to evaluate the thermal performance of medium-temperature solar collectors was developed. The experimental analysis shows the evacuated-tube solar collector performed better with a heat shield, especially at higher working temperatures. The collection efficiency of the solar collector with a heat shield was 54.70% at the highest inlet temperature of 123.9 °C during the test period, which is 31.49% higher than for the solar collector without a heat shield. The calculated heat-loss coefficient for the evacuated-tube solar collector with a heat shield was 1.86 W/(m2 K), which is an improvement of 50.80% compared with that of the collector without a heat shield

  6. Modelisation, conception et simulation des performances d'un collecteur solaire aeraulique a tubes sous vide en milieu nordique

    Science.gov (United States)

    Paradis, Pierre-Luc

    The global energy consumption is still increasing year after year even if different initiatives are set up to decrease fossil fuel dependency. In Canada 80% of the energy is used for space heating and domestic hot water heating in residential sector. This heat could be provided by solar thermal technologies despite few difficulties originating from the cold climate. The aim of this project is to design a solar evacuated tube thermal collector using air as the working fluid. Firstly, needs and specifications of the product are established in a clear way. Then, three concepts of collector are presented. The first one relies on the standard evacuated tube. The second one uses a new technology of tubes; both sides are open. The third one uses heat pipe to extract the heat from the tubes. Based on the needs and specification as criteria, the concept involving tubes with both sides open has been selected as the best idea. In order to simulate the performances of the collector, a model of the heat exchanges in an evacuated tube was developed in 4 steps. The first step is a model in steady state intended to calculate the stagnation temperature of the tube for a fixed solar radiation, outside temperature and wind speed. As a second step, the model is generalised to transient condition in order to validate it with an experimental setup. A root mean square error of 2% is then calculated. The two remainder steps are intended to calculate the temperature of airflow leaving the tube. In the same way, a first model in steady state is developed and then generalised to the transient mode. Then, the validation with an experimental setup gave a difference of 0.2% for the root mean square error. Finally, a preindustrial prototype intended to work in open loop for preheating of fresh air is presented. During the project, explosion of the both sides open evacuated tube in overheating condition blocked the construction of a real prototype for the test. Different path for further work are also identified. One of these is in relation with CFD simulation of the uniformity of the airflow inside of the collector. Another one is the analysis of the design with a design of experiment plan.

  7. Visualization Study of the Effect of the Prolonged Vertical Tube on the Separation Performance of a Cyclone

    Science.gov (United States)

    Qian, Fuping; Zhang, Mingyao

    2007-06-01

    Cyclones have been widely used in different industrial processes. The most widely used experimental observation techniques for the flow pattern include Pitot tubes; hot-wire anemometers, as well as the non-intrusive techniques such as laser Doppler anemometry (LDA). However, all these available techniques have the limitation of only one-point measurement at a time, by which the whole-field fluid characterization in cyclones cannot be obtained simultaneously. Particle image velocimetry (PIV) is a novel non-intrusive visualization experimental technique to measure the whole-field three-dimensional fluid velocity instantaneously. However, only a few papers that examined the flow pattern in cyclones with PIV have been found. The objective of this work is to carry out an elementary experimental investigation of the effect of the prolonged vertical tube on the separation performance of a cyclone by PIV. Since the tangential velocity results in the centrifugal force for particle separation, and is regarded as the most important component of the gas flow in a cyclone, this paper only presents this velocity component. To facilitate visual observation all cyclone parts are constructed of perspex. The lengths of the prolonged vertical tube (attaching a vertical tube at the bottom of the dust outlet) are 0.30m, 0.40m and 0.50m, respectively. Experiments were conducted at 18m/s inlet gas velocity. The model cyclone is set horizontally in order to take images by charge coupled device (CCD) easily. Particles of about 1 ?m in diameter are added as tracer particles. They are generated by the atomizer. Air with tracer particles is sucked into the cyclone through the entry, subsequently travels through outlet tube of the cyclone and the gate valve, and is discharged into the atmosphere. The experimental results show that a typical Rankine vortex with inner quasi-forced vortex and outer quasi-free vortex in the vertical tube and dustbin which are the same as that in the body of the cyclone; the tangential velocity in the dustbin reduces1 greatly when the prolonged vertical tube attaching into the dust outlet, which can avoid the re-entrainment of already separated dust effectively. The results also indicate that PIV technique can be used to measure the strong swirl gas flow such as cyclones, and the prolonged vertical tube has practical significance for improving the separation performance of a cyclone.

  8. Research on Under-actuated Flexible Pectoral Fin of Labriform Fish

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2012-06-01

    Full Text Available The new propulsor, whose inspiration is from pectoral fins of fishes, has arisen increasing attention. To improve the performance of the existing labriform bionic pectoral fin, based on the structure and control mechanism of real fish pectoral fin, the under-actuated technology was utilized to design a new flexible bionic pectoral fin. Then, the kinematic model of pectoral fin during fish forward steady swimming and the dynamic model of bionic pectoral was built. Finally, Matlab was used to simulate the kinematic and dynamic performance of bionic pectoral fin. The simulation result shows that the new flexible bionic pectoral fin can imitate the propulsion motion morphology of pectoral fin during fish forward steady swimming well. However, due to the restriction of kinematic model of pectoral fin and structure as well as physical properties of bionic fin ray, there is still tolerance between the locomotion morphology of bionic pectoral fin and that of real fish. Therefore, it is necessary to develop further research on kinematic modeling of pectoral fin and bionic design of fin ray. Additionally, the new bionic pectoral fin reduces the number of the driving variables, providing the possibility and the basis of further reducing the volume as well as the complexity of bionic device of pectoral fin.

  9. Successful euthanasia of a juvenile fin whale.

    OpenAIRE

    Daoust, P. Y.; Ortenburger, A. I.

    2001-01-01

    A stranded juvenile fin whale was successfully euthanized with an intravenous injection of sedative and cardioplegic drugs. Veterinarians may face a number of serious difficulties if called to perform this task, and advance preparation is required for successful euthanasia of these animals.

  10. Critical heat flux experiments using a screw tube under DEMO divertor-relevant cooling conditions

    International Nuclear Information System (INIS)

    As part of the development of plasma-facing components (PFCs) for fusion machines, JAEA has been developing high-performance cooling tubes with pressurized water flow. Along this line, a cooling tube with a helical triangular fin on its inner surface has been recently proposed for application in a fusion DEMO to enhance heat removal. Since the fin can be machined via simple mechanical threading, this tube is called as a 'screw tube'. The divertor cooling conditions for the JAEA DEMO design will be a pressure of 4 MPa and an outlet temperature of 200 deg. C, in order to improve the thermal efficiency of power generation. In the this study, the effect of subcooling on the critical heat flux (CHF) by the screw tube has been investigated under DEMO divertor-relevant conditions, with the local pressure of 4 MPa and the inlet coolant temperature up to 180 deg. C. A test sample of the screw tube is made of pure Cu instead of F82H, a candidate structural material for the DEMO divertor. The results show that the ICHF values of the screw tube are more than double the values of the smooth tube at the inlet coolant temperature of 180 deg. C, although the temperature rise of the cooling water by 140 K leads to a reduction in the ICHF by almost half as compared with those values at room temperature

  11. Big brains are not enough: performance of three parrot species in the trap-tube paradigm.

    Science.gov (United States)

    Liedtke, Jannis; Werdenich, Dagmar; Gajdon, Gyula K; Huber, Ludwig; Wanker, Ralf

    2011-01-01

    The trap-tube task has become a benchmark test for investigating physical causality in vertebrates. In this task, subjects have to retrieve food out of a horizontal tube using a tool and avoiding a trap hole in the tube. Great apes and corvids succeeded in this task. Parrots with relative brain volumes comparable to those of corvids and primates also demonstrate high cognitive abilities. We therefore tested macaws, a cockatoo, and keas on the trap-tube paradigm. All nine parrots failed to solve the task. In a simplified task, trap tubes with a slot inserted along the top were offered. The slot allowed the birds to move the reward directly with their bills. All but one individual solved this task by lifting the food over the trap. However, the parrots failed again when they were prevented from lifting the reward, although they anticipated that food will be lost when moved into the trap. We do not think that the demanding use of an external object is the main reason for the parrots' failure. Moreover, we suppose these parrots fail to consider the trap's position in the beginning of a trial and were not able to stop their behaviour and move the reward in the trap's opposite direction. PMID:20814805

  12. Benchmarking the Performance of the ANSYS-FLUENT Standard k- ? Turbulence Model in Fluid Flow and Heat Transfer Predictions for Complex Flows around Circular Pin-Fins Using Various near Wall Functions

    OpenAIRE

    Al-witry, A.; Es-saheb, M.

    2013-01-01

    This study compares CFD analyses of the fluid flow and heat transfer phenomena in a popular pin-fin geometry of X/D = 2.5, S/D = 2.5 and H/D = 1 for a range of Re = 5,000 to 30,000 to those from experiment to aid in the benchmarking the performance of the CFD code FLUENT. The CFD analyses use three ANSYS-FLUENT (version 13) near wall treatments available within the code: 1) the Standard Wall Function (SWF), 2) the Non-Equilibrium Wall Function (NEWF) and 3) the enhanced wall treatment. Experi...

  13. Hydrothermal Preparation of Gd3+Doped Titanate Nano tubes: Magnetic Properties and Photovoltaic Performance

    International Nuclear Information System (INIS)

    Pure and Gd3+ doped titanate nano tubes (TNTs) materials were synthesized by a hydrothermal method. Their morphology, optical properties, thermal stability, and magnetic properties were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis spectroscopy, thermal analysis, and magnetic measurements. It was found that doping renders Gd3+ TNT visible light active and results in smaller crystallite size and larger surface area as well as higher thermal stability compared to pure titanate nano tubes. The estimated magnetic moments point to presence of weak antiferromagnetic interaction. Application of the prepared Gd3+ TNT for modifying conventional photoanodes in polymer solar cells was attempted. Preliminary results show slightly improved photovoltaic energy conversion efficiency in the devices containing the newly designed Gd3+ doped nano tubes.

  14. Sensitization and performances of S1 image converter tubes designed for laser fusion experiments

    International Nuclear Information System (INIS)

    S1 streak cameras with time resolution better than 10 ps are now currently available at the Centre d'Etudes de Limeil. They integrate a standard P 500 image converter tube slightly modified to allow the S1 photocathode's deposition. Almost 70% of the tubes have 1.06 ?m sensitivity greater than 50 ?A/w and 60% are in the 100 to 400 ?A/w range. It is also possible to regenerate the 1.06 ?m sensitivity when necessary, thus solving the difficult lifetime problem of these tubes. Dynamic range of a few hundreds is possible for 47 ps I.R. laser pulses and more than 64 for 12 ps pulses

  15. Modelling of in-reactor creep of KOFA cladding tube and performance evaluation of KOFA fuel rod

    International Nuclear Information System (INIS)

    Even if a tube is manufactured in accordance with the given specification, creep properties can vary unless all the manufacturing processes are exactly of the same from the ingot fabrication to the final heat treatment. Especially the characterization tests exibit that the thermal creep behavior of KOFA cradding tube made to the KAERI specification which from that of KWU tube but is found almost identical to W tube made to W's own specification which is quite different from the KAERI specification. As the in-reactor creep is assumed to comprise the thermal creep component and the irradiation creep component, the thermal creep model of KOFA cradding tube was developed based on the measured thermal creep data whereas the irradiation creep model of KOFA cladding tube was established based on the referenced data of irradiation creep of W tube. In order to see the effect of newly developed KOFA cladding creep on KOFA fuel performances, the clad strain and rod internal pressure under ANSI I and II operating conditions were investigated with the use of CARO D5-K in which the new KOFA cladding model has replaced the old creep model. The performance calculation displays that the higher the in-reactor creep, the earlier the fuel clad contact occurs, leading to the increased clad strain. Clad strain of a KOFA fuel rod under steady state operating condition increases by 0.46% but still fulfills the design requirement associated with 2.5% plastic strain limit. However, clad strain of a KOFA fuel rod under power transient can increase to a maximum of 0.17% and the most conservative strain exceeds the design limit of 1.0%. It was proposed that the use of Fq burndown curve to reduce the local peak power level to less than 550 W/cm at around the burnup of 19-20 MWd/KgU would result in lower clad strain than 1.0%. On the contrary, the higher clad creep is benificial from the standpoint of rod internal pressure which may be a limiting factor for the high burnup operation. The rod internal pressure was found to decrease by 3 bar. (Author)

  16. Fully-Implicit Navier-Stokes (FIN-S)

    Science.gov (United States)

    Kirk, Benjamin S.

    2010-01-01

    FIN-S is a SUPG finite element code for flow problems under active development at NASA Lyndon B. Johnson Space Center and within PECOS: a) The code is built on top of the libMesh parallel, adaptive finite element library. b) The initial implementation of the code targeted supersonic/hypersonic laminar calorically perfect gas flows & conjugate heat transfer. c) Initial extension to thermochemical nonequilibrium about 9 months ago. d) The technologies in FIN-S have been enhanced through a strongly collaborative research effort with Sandia National Labs.

  17. A Three Dimensional Performance Analysis of a Developed Evacuated Tube Collector using a CFD Fluent Solar Load Model

    OpenAIRE

    Ali Basil. H.; Gilani S. I.; Al-Kayiem Hussain H.

    2014-01-01

    For the flow through type selected geometry of the designed evacuated tube collector ETC, a three dimensional simulation and analysis of the thermal performance was done, using the ray-tracing solar load model provided by the ANSYS-FLUENT software. In this model the solar radiation heat flux is solved using fair weather condition radiation equations, and then solar radiation load is considered as a heat source term in the energy equation. The thermal effects of the fluid flow and heat transfe...

  18. Brush/Fin Thermal Interfaces

    Science.gov (United States)

    Knowles, Timothy R.; Seaman, Christopher L.; Ellman, Brett M.

    2004-01-01

    Brush/fin thermal interfaces are being developed to increase heat-transfer efficiency and thereby enhance the thermal management of orbital replaceable units (ORUs) of electronic and other equipment aboard the International Space Station. Brush/fin thermal interfaces could also be used to increase heat-transfer efficiency in terrestrial electronic and power systems. In a typical application according to conventional practice, a replaceable heat-generating unit includes a mounting surface with black-anodized metal fins that mesh with the matching fins of a heat sink or radiator on which the unit is mounted. The fins do not contact each other, but transfer heat via radiation exchange. A brush/fin interface also includes intermeshing fins, the difference being that the gaps between the fins are filled with brushes made of carbon or other fibers. The fibers span the gap between intermeshed fins, allowing heat transfer by conduction through the fibers. The fibers are attached to the metal surfaces as velvet-like coats in the manner of the carbon fiber brush heat exchangers described in the preceding article. The fiber brushes provide both mechanical compliance and thermal contact, thereby ensuring low contact thermal resistance. A certain amount of force is required to intermesh the fins due to sliding friction of the brush s fiber tips against the fins. This force increases linearly with penetration distance, reaching 1 psi (6.9 kPa) for full 2-in. (5.1 cm) penetration for the conventional radiant fin interface. Removal forces can be greater due to fiber buckling upon reversing the sliding direction. This buckling force can be greatly reduced by biasing the fibers at an angle perpendicularly to the sliding direction. Means of containing potentially harmful carbon fiber debris, which is electrically conductive, have been developed. Small prototype brush/fin thermal interfaces have been tested and found to exhibit temperature drops about onesixth of that of conventional meshing-fin thermal interface, when fabricated as a retrofit. In this case, conduction through the long, thin metal fins themselves becomes a thermal bottleneck. Further improvement could be made by prescribing aluminum fins to be shorter and thicker than those of the conventional meshing-fin thermal interfaces; the choice of height and thickness would be optimized to obtain greater overall thermal conductance, lower weight, and lower cost.

  19. Air Flow Around Finned Cylinders

    Science.gov (United States)

    Brevoort, M J; Rollin, Vern G

    1937-01-01

    Report presents the results of a study made to determine the air-flow characteristics around finned cylinders. Air-flow distribution is given for a smooth cylinder, for a finned cylinder having several fin spacings and fin widths, and for a cylinder with several types of baffle with various entrance and exit shapes. The results of these tests show: that flow characteristics around a cylinder are not so critical to changes in fin width as they are to fin spacing; that the entrance of the baffle has a marked influence on its efficiency; that properly designed baffles increase the air flow over the rear of the cylinder; and that these tests check those of heat-transfer tests in the choice of the best baffle.

  20. Enhancement of the Remote Field Eddy Current Testing Performed from Outside of a Magnetic Tube

    Directory of Open Access Journals (Sweden)

    Daniela Gombarska

    2006-01-01

    Full Text Available The paper deals with design of remote field eddy current probe for non-destructive testing dedicated for inspection of ferromagnetic tubular material from outside. The remote field effect inside the tube wall is achieved by the medium of a magnetic shield covering the probe. Results of numeric simulations made for verification of probe characteristics confirmed the effectiveness of probe design.

  1. Enhancement of the remote field eddy current testing performed from outside of a magnetic tube

    OpenAIRE

    Daniela Gombarska; Tomas Marek

    2006-01-01

    The paper deals with design of remote field eddy current probe for non-destructive testing dedicated for inspection of ferromagnetic tubular material from outside. The remote field effect inside the tube wall is achieved by the medium of a magnetic shield covering the probe. Results of numeric simulations made for verification of probe characteristics confirmed the effectiveness of probe design.

  2. A study of the high vacuum engineering for the accelerator tube construction has performed

    International Nuclear Information System (INIS)

    Failure of the accelerator tube vacuum systems due to construction and physical chemistry aspect are reported in this study. The problem solving are presented in this paper, where the results of this engineering concepts are met with the requirement of the technical specifications. (author)

  3. In-pile performance of a double-walled tube and a tritium permeation barrier

    Science.gov (United States)

    Magielsen, A. J.; Bakker, K.; Chabrol, C.; Conrad, R.; van der Laan, J. G.; Rigal, E.; Stijkel, M. P.

    2002-12-01

    In two recent irradiation experiments in the HFR Petten, tritium permeation rates through representative materials to be used as cooling tubes of the water-cooled lithium-lead blanket have been measured in-pile. These latest experiments in the EXOTIC 8 series (E 8.9 and E 8.10) are made of a double wall tube (DWT) and a T91 tube with an Fe-Al/Al 2O 3 layer acting as tritium permeation barrier (TPB). These tubes contain annular pebble beds of ceramic breeder materials for the helium-cooled pebble bed concept blanket as tritium breeding material. Both experiments are built up of two concentric and independently purged containments allowing on-line tritium release rate and permeation rate measurements. In-pile operation has ended in March 2001 after 450 full power days and resulted in an irradiation damage of approximately 2.6 and 3.2 dpa, respectively in T91 steel. This paper reports on the experimental results obtained for in-pile tritium permeation and discusses the influence of purge gas compositions, temperature and irradiation on tritium permeation through the DWT and TPB.

  4. DEVELOPMENT OF A REPRODUCIBLE SCREENING METHOD TO DETERMINE THE MECHANISM AND EFFECT OF ORGANIC ACIDS AND OTHER CONTAMINANTS ON THE CORROSION OF ALUMINUM-FINNED COPPER-TUBE HEAT EXCHANGE COILS

    Energy Technology Data Exchange (ETDEWEB)

    Richard A. Corbett; Dave Severance

    2005-02-01

    Formicary corrosion is an insidious form of localized pitting corrosion. Notoya (1997b) wrote, ?In Japan, this type of corrosion is found in approximately 10% of cases of premature failure of copper tubes.? Attack characteristically features very small surface pits which are not visible to the un-aided eye, and random directional changes in the underlying copper metal. Attack is rapid. Failures have occurred before installation, shortly thereafter, or within several years later. Objectives of this Research Project Conduct an in depth literature search on the subject of formicary corrosion. Define the corrosion mechanism. Develop a test method that will reproduce formicary corrosion. Develop a test method for screening candidate materials that could cause formicary corrosion.

  5. An Experimental Modeling and Investigation of Change in Cold Mass Fraction and Nozzle Numbers on Performance of Counter Flow Vortex Tube

    Science.gov (United States)

    Mohanty, S. S.; Ray, D. K.

    2012-06-01

    An experimental investigation has been performed to realize thorough behavior of a vortex tube system. The vortex tube is a simple device operating as a refrigerating unit without any moving parts. It consists of a principal tube, to which a high pressure gas stream enters tangentially where it splits into two streams: one hot and one cold temperature streams. This paper discusses the experimental investigation of vortex tube performance as it relates to cold mass fraction, and nozzle number. Four different orifices, each with three, four, five and six nozzles respectively, were manufactured and used during the test. The experiments have been conducted with each one of those orifices stated above, and the performance of the vortex tube has been tested with air at inlet pressure of 5 bar and the cold mass fractions of 0.5-0.72.

  6. Controlled Thermal-Mechanical Processing of Tubes and Pipes for Enhanced Manufacturing and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Kolarik, Robert V.

    2005-11-11

    The Alloy Steel Business of The Timken Company won an award for the controlled thermo-mechanical processing (CTMP) project and assembled a strong international public/private partnership to execute the project. The premise of the CTMP work was to combine Timken's product understanding with its process expertise and knowledge of metallurgical and deformation fundamentals developed during the project to build a predictive process design capability. The CTMP effort succeeded in delivering a pc-based capability in the tube optimization model, with a virtual pilot plant (VPP) feature to represent the desired tube making process to predict the resultant microstructure tailored for the desired application. Additional tasks included a system for direct, online measurement of grain size and demonstration of application of CTMP via robotically enhanced manufacturing.

  7. Performance and lifetime of micro-channel plate tubes for the TORCH detector

    Science.gov (United States)

    Gys, T.; García, L. Castillo; Fopma, J.; Forty, R.; Frei, C.; Gao, R.; Harnew, N.; Keri, T.; Piedigrossi, D.

    2014-12-01

    Timing Of internally Reflected CHerenkov photons (TORCH) is a time-of-flight detector proposed for particle identification at low momentum. Charged particles passing through a plane of quartz produce Cherenkov light, some of which is trapped within the plane by total internal reflection and then emerges at the edges. There the photons are focused onto micro-channel plate photon detectors that register their position and arrival time. This allows reconstructing the photon trajectories in quartz and determining the particle crossing time. Commercial micro-channel plate tubes can achieve the required timing resolution, but their anode spatial segmentation is too coarse, at least in one dimension. In addition, these devices must survive a number of years in a high occupancy environment. Micro-channel plate tubes specifically dedicated to the TORCH are currently being designed, constructed and prototyped in collaboration with industry. In the present paper, results from commercial and dedicated devices are reported.

  8. Study of transient behavior of finned coil heat exchangers

    Science.gov (United States)

    Rooke, S. P.; Elissa, M. G.

    1993-01-01

    The status of research on the transient behavior of finned coil cross-flow heat exchangers using single phase fluids is reviewed. Applications with available analytical or numerical solutions are discussed. Investigation of water-to-air type cross-flow finned tube heat exchangers is examined through the use of simplified governing equations and an up-wind finite difference scheme. The degenerate case of zero air-side capacitance rate is compared with available exact solution. Generalization of the numerical model is discussed for application to multi-row multi-circuit heat exchangers.

  9. Toward quantum FinFET

    CERN Document Server

    Wang, Zhiming

    2013-01-01

    This book reviews a range of quantum phenomena in novel nanoscale transistors called FinFETs, including quantized conductance of 1D transport, single electron effect, tunneling transport, etc. The goal is to create a fundamental bridge between quantum FinFET and nanotechnology to stimulate readers' interest in developing new types of semiconductor technology. Although the rapid development of micro-nano fabrication is driving the MOSFET downscaling trend that is evolving from planar channel to nonplanar FinFET, silicon-based CMOS technology is expected to face fundamental limits in the near future. Therefore, new types of nanoscale devices are being investigated aggressively to take advantage of the quantum effect in carrier transport. The quantum confinement effect of FinFET at room temperatures was reported following the breakthrough to sub-10nm scale technology in silicon nanowires. With chapters written by leading scientists throughout the world, Toward Quantum FinFET provides a comprehensive introductio...

  10. Effect of fins and repeated-rib roughness on the performance characteristics of a reactor vessel air cooling system for LMFBR shutdown heat removal

    International Nuclear Information System (INIS)

    The use of a totally passive cooling system for shutdown heat removal that rejects heat from the reactor vessel by radiation to the guard vessel and from the guard vessel to a circulating air stream driven by natural convection is a key feature of the US Department of Energy's liquid-metal reactor advanced design study concepts. General Electric refers to the system as the Reactor Vessel Auxiliary Cooling System (RVACS) and Rockwell International as the Reactor Auxiliary Cooling System (RACS). The circulating air stream is contained in the annular passage formed with guard vessel wall and the duct wall surrounding the guard vessel. Specifically, the RVACS/RACS is designed to assure adequate cooling of the reactor vessel under abnormal operational conditions associated with loss of heat removal through the normal heat transport path via the steam generator system or the DRACS, if available. To enhance the heat transfer, longitudinal radial fins or repeated ribs can be attached to the duct wall and/or the guard vessel. The purpose of the present paper is to summarize the status of the analytical work on the development of an optimum design configuration for the RVACS/RACS

  11. Subcooled freon-11 flow boiling in top-heated finned coolant channels with and without a twisted tape

    Science.gov (United States)

    Smith, Alvin; Boyd, Ronald D., Sr.

    An experimental study was conducted in top-heated finned horizontal tubes to study the effect of enhancement devices on flow boiling heat transfer in coolant channels. The objectives are to examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for circular coolant channels with spiral finned walls and/or spiral fins with a twisted tape, and improve the data reduction technique of a previous investigator. The working fluid is freon-11 with an inlet temperature of 22.2 C (approximately 21 C subcooling). The coolant channel's exit pressure and mass velocity are 0.19 M Pa (absolute) and 0.21 Mg/sq. ms, respectively. Two tube configurations were examined; i.e., tubes had either 6.52 (small pitch) or 4.0 (large pitch) fins/cm of the circumferential length (26 and 16 fins, respectively). The large pitch fins were also examined with a twisted tape insert. The inside nominal diameter of the copper channels at the root of the fins was 1.0 cm. The results show that by adding enhancement devices, boiling occurs almost simultaneously at all axial locations. The case of spiral fins with large pitch resulted in larger mean (circumferentially averaged) heat transfer coefficients, h sub m, at all axial locations. Finally, when twisted tape is added to the tube with large-pitched fins, the power required for the onset of boiling is reduced at all axial and circumferential locations.

  12. Feasibility study to perform coiled tubing drilling on Gullfaks-A

    OpenAIRE

    Albawi, Ahmed Haimet

    2013-01-01

    This report is carried out as part of Decision gate1 (DG1) feasibility study conducted for the possibility of commencing coiled tubing drilling to drill slim holes simultaneously with other drilling activities on Gullfaks A (GF-A). A number of wells on GF-A platform has been closed and experienced oil production drop due to different reasons. However there are still small reservoirs with oil left in place which can be drilled through their mother wells to act as producer or injector wells in ...

  13. Unsteady Ejector Performance: An Experimental Investigation Using a Resonance Tube Driver

    Science.gov (United States)

    Wilson, Jack; Paxson, Daniel E.

    2002-01-01

    A statistically designed experiment to characterize thrust augmentation for unsteady ejectors has been conducted at the NASA Glenn Research Center. The variable parameters included ejector diameter, length, and nose radius. The pulsed jet driving the ejectors was produced by a shrouded resonance (or Hartmann-Sprenger) tube. In contrast to steady ejectors, an optimum ejector diameter was found, which coincided with the diameter of the vortex ring created at the pulsed jet exit. Measurements of ejector exit velocity using a hot-wire permitted evaluation of the mass augmentation ratio, which was found to correlate to thrust augmentation following a formula derived for steady ejectors.

  14. PERFORMANCE OF EVACUATED TUBE SOLAR COLLECTOR USING WATER-BASED TITANIUM OXIDE NANOFLUID

    OpenAIRE

    M. Mahendran; G.C. Lee; Sharma, K. V.; A. Shahrani; R. A. Bakar

    2012-01-01

    Experiments are undertaken to determine the efficiency of an evacuated tube solar collector using water-based Titanium Oxide (TiO2) nanofluid at the Pekan Campus (3?32’ N, 103?25’ E), Faculty of Mechanical Engineering, University Malaysia Pahang, for the conversion of solar thermal energy. Malaysia lies in the equatorial zone with an average daily solar insolation of more than 900 W/m², which can reach a maximum of 1200 W/m² for most of the year. Traditionally water is pumped through ...

  15. Performance and Mechanical Tolerances Achieved with a Full Size Prototype of a CMS Barrel Muon Drift Tubes Chamber

    CERN Document Server

    Bethke, Siegfried; Benettoni, Massimo; Benvenuti, Alberto; Berdugo, Javier; Cerrada, Marcos; Colino, Nicanor; Conti, Enrico; Dallavalle, Gaetano-Marco; Daniel, Manuel; De Giorgi, Marco; De Min, Alberto; Dosselli, Umberto; Fanin, Claudio; Fouz-Iglesias, M C; Gasparini, Fabrizio; Gasparini, Ugo; Giantin, R; Grandi, Claudio; Guaita, Paola; Guerzoni, Marco; Ladrón de Guevara, Pedro; Lippi, Ivano; Marcellini, Stefano; Martinelli, Roberto; Meneguzzo, Anna Teresa; Mocholí-Mocholí, J; Montanari, Alessandro; Montanari, Christian; Navarria, Francesco; Odorici, Fabrizio; Reithler, Hans; Romero, Luciano; Rossi, Antonio; Rovelli, Tiziano; Schwarthoff, Hubert; Sondermann, Volker; Tano, Valeria; Teykal, Helmut; Tutas, Joerg; Van den Hirtz, J; Wagner, H; Wegner, Martin; Willmott, Carlos

    1998-01-01

    The barrel muon chambers of the CMS experiment are made assembling 3 independent modules ( SuperLayers) which together measure the impact point and the angles theta and phi. Each SuperLayer consists of four layers of rectangular Drift Tubes. MB96 is a full size prototype of the smallest CMS Barrel Muon Chamber ( MB1) built in early 1997 at the Legnaro INFN laboratory and tested in summer 1997 at the CERN CMS test beam facility. The performance of the prototype and the mechanical tolerances achieved in the construction are presented.

  16. Evaluating the Fin-ray Trajectory Tracking of Bio-inspired Robotic Undulating Fins via an Experimental-numerical Approach

    Directory of Open Access Journals (Sweden)

    Xiaojia Xiang

    2014-07-01

    Full Text Available In the past decade, biomimetic undulating fin propulsion has been one of the main topics considered by scientists and researchers in the field of robotic fish. This technology is inspired by the biological wave-like propulsion of ribbon-finned fish. The swimming modes have aquatic application potentials with greater manoeuvrability, less detectable noise or wake and better efficiency at low speeds. The present work concentrates on the evaluation of fin-ray trajectory tracking of biorobotic undulating fins at the levels of kinematics and hydrodynamics by using an experimental-numerical approach. Firstly, fin-ray tracking inconsistence between the desired and actual undulating trajectories is embodied with experimental data of the fin prototype. Next, the dynamics' nonlinearity is numerically and analytically unveiled by using the computational fluid dynamics (CFD method, from the viewpoint of vortex shedding and the hydro-effect. The evaluation of fin-ray tracking performance creates a good basis for control design to improve the fin-ray undulation of prototypes.

  17. Metal/ceramic niobium composite fin heat pipes for a low mass radiator

    International Nuclear Information System (INIS)

    Niobium/alumina composite materials show promise for providing low mass fin heat pipes for space heat rejection systems. These heat pipes would be incorporated into a large radiator for waste heat rejection from a space nuclear power source. Current fabrication technology limits the heat pipes to straight lengths, although different cross-sections can be fabricated. A radiator analytical model was developed and used to examine the effects of fin pipe cross-section and fin material on radiator mass. Carbon-Carbon, Compglas, and beryllia fins were examined. The overall radiator mass was only slightly affected by the choice of material, however, the carbon-carbon design required fewer fin heat pipes. Radiators with carbon-glass composite (Compglas) fins had a slightly higher mass, but may still be attractive based on the other properties of Compglas, including resistance to atomic oxygen, and the ability to be fabricated into thin sheets. Square Nb/Alumina tubes have already been fabricated, while rectangular niobium composite tube is under development. These tubes will be bonded to carbon-carbon or Compglas fins, and fabricated into sodium heat pipes

  18. A preliminary study into performing routine tube output and automatic exposure control quality assurance using radiology information system data

    International Nuclear Information System (INIS)

    Data are currently being collected from hospital radiology information systems in the North West of the UK for the purposes of both clinical audit and patient dose audit. Could these data also be used to satisfy quality assurance (QA) requirements according to UK guidance? From 2008 to 2009, 731 653 records were submitted from 8 hospitals from the North West England. For automatic exposure control QA, the protocol from Inst. of Physics and Engineering in Medicine (IPEM) report 91 recommends that milli amperes per second can be monitored for repeatability and reproducibility using a suitable phantom, at 70-81 kV. Abdomen AP and chest PA examinations were analysed to find the most common kilo voltage used with these records then used to plot average monthly milli amperes per second with time. IPEM report 91 also recommends that a range of commonly used clinical settings is used to check output reproducibility and repeatability. For each tube, the dose area product values were plotted over time for two most common exposure factor sets. Results show that it is possible to do performance checks of AEC systems; however more work is required to be able to monitor tube output performance. Procedurally, the management system requires work and the benefits to the workflow would need to be demonstrated. (authors)

  19. Finned Carbon-Carbon Heat Pipe with Potassium Working Fluid

    Science.gov (United States)

    Juhasz, Albert J.

    2010-01-01

    This elemental space radiator heat pipe is designed to operate in the 700 to 875 K temperature range. It consists of a C-C (carbon-carbon) shell made from poly-acrylonitride fibers that are woven in an angle interlock pattern and densified with pitch at high process temperature with integrally woven fins. The fins are 2.5 cm long and 1 mm thick, and provide an extended radiating surface at the colder condenser section of the heat pipe. The weave pattern features a continuous fiber bath from the inner tube surface to the outside edges of the fins to maximize the thermal conductance, and to thus minimize the temperature drop at the condenser end. The heat pipe and radiator element together are less than one-third the mass of conventional heat pipes of the same heat rejection surface area. To prevent the molten potassium working fluid from eroding the C C heat pipe wall, the shell is lined with a thin-walled, metallic tube liner (Nb-1 wt.% Zr), which is an integral part of a hermetic metal subassembly which is furnace-brazed to the inner surface of the C-C tube. The hermetic metal liner subassembly includes end caps and fill tubes fabricated from the same Nb-1Zr alloy. A combination of laser and electron beam methods is used to weld the end caps and fill tubes. A tungsten/inert gas weld seals the fill tubes after cleaning and charging the heat pipes with potassium. The external section of this liner, which was formed by a "Uniscan" rolling process, transitions to a larger wall thickness. This section, which protrudes beyond the C-C shell, constitutes the "evaporator" part of the heat pipe, while the section inside the shell constitutes the condenser of the heat pipe (see figure).

  20. SIMULATION OF BOILING HEAT TRANSFER AROUND MICRO PIN-FIN HEAT EXCHANGER: PROGRESS AND CHALLENGES

    International Nuclear Information System (INIS)

    Boiling at microscales is a challenging problem for the computational models as well as the resources. During boiling, the formation and departure of vapor bubbles from the heated surface involves the physics from nano/micro level to the macro level. Therefore, a hierarchical methodology is needed to incorporate the nano/microscale physics with the macroscale system performance. Using micro-fabrication techniques, microstructures (micropin-fins) can be fabricated around the tubes in the heat exchanger of Pressurized Water Reactors (PWRs) to increase the heat-exchanging efficiency and reduce the overall size of the heat-exchanger for the given heat transfer rates. Combined with high fidelity simulations of the thermal transport in the entire system, optimal design of microstructure patterns and layouts can be worked out pragmatically. Properly patterned microstructures on the pipe in the steam generation zone should create more nuclei for bubble to form and result in a reduced average bubble size and shorter retention time, i.e. the time for the vapor phase sticking on the pipe surface. The smaller average steam bubble size and shorter bubble retention time will enhance the overall thermal efficiency. As a preliminary step, a periodic arrangement of micropin-fins containing four in-line cylindrical fins was modeled. The governing equations for the mass, momentum and energy transport were solved in the fluid in a conjugate heat transfer mode. In the future, several studies will be conducted to simulate different geometric arrangements, different fin cross-sections, and realistic operating conditions including phase-change with boiling by adding complexities in simple steps

  1. Thermal performance of a solar cooker based on an evacuated tube solar collector with a PCM storage unit

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, S.D.; Sagara, Kazunobu [Osaka Univ., Dept. of Architectural Engineering, Suita, Osaka (Japan); Iwata, Takeshi; Kitano, Hiroaki [Mie Univ., Dept. of Architecture, Tsu (Japan)

    2005-03-01

    The thermal performance of a prototype solar cooker based on an evacuated tube solar collector with phase change material (PCM) storage unit is investigated. The design has separate parts for energy collection and cooking coupled by a PCM storage unit. Solar energy is stored in the PCM storage unit during sunshine hours and is utilized for cooking in late evening/night time. Commercial grade erythritol was used as a latent heat storage material. Noon and evening cooking experiments were conducted with different loads and loading times. Cooking experiments and PCM storage processes were carried out simultaneously. It was observed that noon cooking did not affect the evening cooking, and evening cooking using PCM heat storage was found to be faster than noon cooking. The cooker performance under a variety of operating and climatic conditions was studied at Mie, Japan. (Author)

  2. Three-phase synchronous motor with HTSL rotor winding and HTSL bearings. Project: HTS motor cooling system with high-performance pulsed tube cooler. Final report

    International Nuclear Information System (INIS)

    A pulsed tube cooler was to be developed for the temperature range of 25-30 K and a high cooling capacity of 40-50 W, and an optimized cooler for the HTS motor was to be constructing. Problems to be solved related to the thermal coupling of the cooler to the rotating HTS rotor (coupled or stationary cooler?) and the performance stability of the pulsed tube boiler. (orig.)

  3. High-performance closed-tube PCR based on switchable luminescence probes

    International Nuclear Information System (INIS)

    Highlights: ? Real-time PCR based on switchable lanthanide luminescence probes. ? Nonfluorescent probes form a highly fluorescent lanthanide chelate complex. ? Self-assembly of the lanthanide ion carrier chelate and the light absorbing antenna. ? Very low background fluorescence and high specific signal generation. ? Improved DNA detection sensitivity leading to diminished PCR threshold cycles. - Abstract: We introduce a switchable lanthanide luminescence reporter technology based closed-tube PCR for the detection of specific target DNA sequence. In the switchable lanthanide chelate complementation based reporter technology hybridization of two nonfluorescent oligonucleotide probes to the adjacent positions of the complementary strand leads to the formation of a highly fluorescent lanthanide chelate complex. The complex is self-assembled from a nonfluorescent lanthanide chelate and a light-harvesting antenna ligand when the reporter molecules are brought into close proximity by the oligonucleotide probes. Outstanding signal-to-background discrimination in real-time PCR assay was achieved due to the very low background fluorescence level and high specific signal generation. High sensitivity of the reporter technology allows the detection of a lower concentration of amplified DNA in the real-time PCR, resulting in detection of the target at the earlier amplification cycle compared to commonly used methods.

  4. Hydraulic performance evaluation of pressure compensating (pc) emitters and micro-tubing for drip irrigation system

    International Nuclear Information System (INIS)

    Drip irrigation system is necessary for those areas, where the water scarcity issues are present. The present study was conducted at the field station of Climate Change, Alternate Energy and Water Resources Institute (CAEWRI), National Agricultural Research Center (NARC), Islamabad, during 2013, regarding drip irrigation system. Drip irrigation system depends on uniform emitter application flow. All the emitters were tested and replicated thrice at pressure head (34 to 207Kpa) with an increment of 34 Kpa. The minimum and maximum discharges were 1.32 - 3.52, 3.36 - 5.42, and 43.22 - 100.99 Lph, with an average of 2.42, 4.63 and 73.66 Lph, for Bow Smith, RIS and Micro-tubing, respectively. It indicates that more than 90% of emission uniformity (EU) and uniformity coefficient (CU) for all Emitters, which shows excellent water application with least standard deviation, ranging 0.12 to 2.37, throughout the operating pressure heads in all emitters. An average coefficient of variation (CV) of all emitters were behaving less than 0.07, indicating an excellent class at all operating pressure heads between 34 to 207 Kpa. Moreover, the relationship of discharge and pressure of emitters indicates that discharge increased with the increase of pressure head. The Q-H curve plays key role in the selection of emitters. (author)

  5. Theoretical research on the performance of a practical helix travelling wave tube

    International Nuclear Information System (INIS)

    On the basis of a rigorous field theory, two different physical models of attenuator and sever have been proposed. One is named High attenuation (HATT) model in which both attenuator and sever are considered as a unified attenuator, but the sever is regarded as an area of very high loss; the other is called Sever and attenuator (SATT) model in which the sever is modelled as a drift area in which the electric and magnetic fields both vanish. A complex function is derived and potential sinking effect is also considered. Thus, a set of more practical self-consistent equations of nonlinear beam-wave interaction is formulated. Simulations are carried out under the conditions of the two different physical models, and the simulation results are compared with the experimental data. The results show that in the case of single signal drive, the unknown second harmonic should be included for predicting the saturated output power. It is also evident that the SATT model and the HATT model predict the same physical nature, whereas the results predicted by the HATT model are much closer to the experimental data than those obtained from the SATT model. Therefore, these results provide a strong theoretical basis for designing broadband and high gain helix travelling wave tubes. (classical areas of phenomenology)

  6. Performances of Dose Measurement of Commercial Electronic Dosimeters using Geiger Muller Tube and PIN Diode

    International Nuclear Information System (INIS)

    There are two categories in personal dosimeters, one is passive type dosimeter such as TLD (thermoluminescence dosimeter) and the other is active type dosimeter such as electronic dosimeter can show radiation dose immediately while TLD needs long time to readout its data by heating process. For improving the reliability of measuring dose for any energy of radiations, electronic dosimeter uses energy filter by metal packaging its detector using aluminum or copper, but measured dose of electronic dosimeter with energy filter cannot be completely compensated in wide radiation energy region. So, in this paper, we confirmed the accuracy of dose measurement of two types of commercial EPDs using Geiger Muller tube and PIN diode with CsI(Tl) scintillator in three different energy of radiation field. The experiment results for Cs-137 was almost similar with calculation value in the results of both electronic dosimeters, but, the other experiment values with Na-22 and Co-60 had higher error comparing with Cs-137. These results were caused by optimization of their energy filters. The optimization was depending on its thickness of energy filter. So, the electronic dosimeters have to optimizing the energy filter for increasing the accuracy of dose measurement or the electronic dosimeter using PIN diode with CsI(Tl) scintillator uses the multi-channel discriminator for using its energy information

  7. CACHE: an extended BASIC program which computes the performance of shell and tube heat exchangers

    International Nuclear Information System (INIS)

    An extended BASIC program, CACHE, has been written to calculate steady state heat exchange rates in the core auxiliary heat exchangers, (CAHE), designed to remove afterheat from High-Temperature Gas-Cooled Reactors (HTGR). Computationally, these are unbaffled counterflow shell and tube heat exchangers. The computational method is straightforward. The exchanger is subdivided into a user-selected number of lengthwise segments; heat exchange in each segment is calculated in sequence and summed. The program takes the temperature dependencies of all thermal conductivities, viscosities and heat capacities into account providing these are expressed algebraically. CACHE is easily adapted to compute steady state heat exchange rates in any unbaffled counterflow exchanger. As now used, CACHE calculates heat removal by liquid weight from high-temperature helium and helium mixed with nitrogen, oxygen and carbon monoxide. A second program, FULTN, is described. FULTN computes the geometrical parameters required as input to CACHE. As reported herein, FULTN computes the internal dimensions of the Fulton Station CAHE. The two programs are chained to operate as one. Complete user information is supplied. The basic equations, variable lists, annotated program lists, and sample outputs with explanatory notes are included

  8. Development of high performance moving-coil linear compressors for space Stirling-type pulse tube cryocoolers

    Science.gov (United States)

    Dang, Haizheng

    2015-06-01

    This paper presents a review of the recent development of moving-coil linear compressors for space Stirling-type pulse tube cryocoolers in National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences. The design, manufacture and assembly methods are described with special emphases laid on linear motor, clearance seal, flexure springs, dual-opposed configuration and flexible design. Several key components are focused on and studied in a detailed way in terms of material selection, geometry design, configuration optimization, manufacture approaches and optimal assembly to achieve high efficiency, easy producibility, high reliability and long life. Experiences from the forerunners and the state-of-the-art approaches are reviewed and used for useful references, while our own successful experiences are emphasized and discussed in more detail together with some lessons learned. A series of compressors for space applications have been worked out with high confidence of reliability and long life expectation, which achieve input capacities of 0-500 W with motor efficiencies of 74.2-83.6%. Single-stage pulse tube cryocoolers driven by these compressors have already covered the temperature range of 25-200 K with cooling capacities varying from milliwatt levels to over 30 W. The commonly-used compressor types and purposes, performance characteristics and their applications in typical space cryocooler projects are also presented.

  9. Experimental Performance of a Solar Thermoelectric Cogenerator Comprising Thermoelectric Modules and Parabolic Trough Concentrator without Evacuated Tube

    Science.gov (United States)

    Miao, L.; Kang, Y. P.; Li, C.; Tanemura, S.; Wan, C. L.; Iwamoto, Y.; Shen, Y.; Lin, H.

    2015-06-01

    A prototype practical solar-thermoelectric cogenerator composed of (1) a primary component of a pile of solar-selective absorber (SSA) slab, thermoelectric (TE) modules, and a depressed water flow tube (multichannel cooling heat sink, MCS), and (2) a parabolic trough concentrator with aperture area of 2m × 2m and east-west focal axis was constructed. Its cogeneration performance under the best climatic and solar insolation conditions in Guangzhou, China was tested. For simplicity, the evacuated glass tube to cover the primary component was eliminated from the system. Six Bi2Te3 TE modules were arranged in series, directly bonded to the rear surface of the solar absorber slab. The hot-side temperature of the TE module reached up to 152°C. The experimentally obtained instantaneous results for the solar to electrical conversion efficiency, heat exchange coefficient of the MCS, and overall system efficiency under the best environmental and solar insolation conditions were about 1.14%, 56.1%, and 49.5%, respectively. To justify these values, an equivalent thermal network diagram based on a single-temperature-node heat transfer model representing the respective system components was used to analyze the thermal transfer and losses of the system. Finally, electrical power of 18° W was generated, with 2 L/min of hot water at 37°C being produced and stored in the insulated container.

  10. Some laboratory-scale corrosion tests on alloy 800 boiler tubing under simulated high-performance boiler conditions

    International Nuclear Information System (INIS)

    Results are described of corosion tests on Alloy 800 boiler tubing from different manufacturers with various compositions and heat treatments. Corrosion capsules were manufactured from standard tubing and filled with solutions to produce chemical environmetns similar to those likely to occur in high-performance boilers at 350 deg.C and above under normal and fault operating conditions. Part of the wall was thinned by machining to give known stress levels at temperature, and a circumferential weld made with Inconel 82 filler material was made in the thinned wall. Tests were continued for 8000 h or until failure, whichever was the shorter. Despite considerable differences in their metallurgical structures and susceptibilities to chemical sensitization tests, the different specimens showed similar corrosion behaviour, the extent and type of attack being largely determined by the solutions in the capsules. Corrosion was slight except in two environments: (i) concentrated chloride solutions with high-pressure oxygen caused extensive pitting and a small amount of cracking, leading to local failure of the wall; (ii) concentration of NaOH>=4% caused failure through cracking, which was most marked near the weld. The addition of SiO2 did not stop cracking in either hydroxide or oxygenated chloride solutions. (author)

  11. Critical heat flux tests using finned rod bundles

    International Nuclear Information System (INIS)

    Rod bundle CHF tests were performed under the low flow conditions to supplement CHF data for HANARO fuel. Test rod has the same geometric configuration as the real HANARO fuel and aluminum cladding with fins is co-extruded on SUS heating tube. There are 3 types of test sections that their shapes are hexagonal with 7 rods, triangular with 3 rods and rectangular with 4 rods. Test bundle has 3 spacers axially and a view window is located in upper region of the test section. Flow patterns until CHF condition are typically varied from bubbly flow to annular flow and then CHF is occurred through long annular flow period. 36 bundle CHF data were obtained in 3 test sections. When bundle CHF data are compared with single rod CHF data, bundle CHF data are larger then single rod CHF data by 4% ? 32%. It is considered that these results are induced by enhancement of turbulence and thermal mixing generated by spacers. It can be seen indirectly that the existing thermal margin analysis for HANARO core has a conservatism because CHF correlation was developed based on single rod data

  12. Forced Convection Heat Transfer Experiments of the Finned Plate in a Duct

    International Nuclear Information System (INIS)

    The studies have been focused on the optimization of fin geometries to maximize the heat transfer rate. The forced convection heat transfer rates were affected largely by the fin spacing, fin height, and tip clearance. As the fin spacing decreases and fin height increases, heat transfers from the fins to the ambient are enhanced as they are directly proportional to the surface area. For a large tip clearance, the fluid tends to escape from the inner fin region to the outer wall region resulting in the decrease of the overall heat removal capability. Thus, the parametric influences of these variables are to be investigated to develop a generalized heat transfer correlation for the geometry. This study is a preliminary experimental study for plate-fin geometries such as fin spacing, fin height and duct width. Mass transfer experiments were carried out based on the analogy concept, using a copper sulfate electroplating system. The work has the relevance with the Reactor Cavity Cooling System performance enhancement study in the VHTR. Forced convection heat transfer experiments were performed for the vertical plate-fins in a duct. Based on the analogy between heat and mass transfer systems, mass transfer rates were measured using the cupric acid copper sulfate electroplating system. The fin spacings were varied from 0.002m to 0.007m, fin heights 0.01m and 0.015m, ReDh from 10 to 6,500, and duct widths from 0.010m to 0.02m. The test results showed that the heat transfer rates enhanced with the increase of fin height and the decrease of fin spacing as they enlarge the heat transfer area. And the heat transfer rates were impaired with the increase of the duct width as the bypass flows increased to tip clearance region

  13. Advancement and performance in large scale eddy current simulations for ISI of FBR steam generator tubes

    International Nuclear Information System (INIS)

    This paper address the performance of large scale eddy current simulations using JAEA supercomputers in order to reliably simulate the in-service inspection of steam generators of fast breeder reactors using eddy currents. (author)

  14. PERFORMANCE OF EVACUATED TUBE SOLAR COLLECTOR USING WATER-BASED TITANIUM OXIDE NANOFLUID

    Directory of Open Access Journals (Sweden)

    M. Mahendran

    2012-12-01

    Full Text Available Experiments are undertaken to determine the efficiency of an evacuated tube solar collector using water-based Titanium Oxide (TiO2 nanofluid at the Pekan Campus (3?32’ N, 103?25’ E, Faculty of Mechanical Engineering, University Malaysia Pahang, for the conversion of solar thermal energy. Malaysia lies in the equatorial zone with an average daily solar insolation of more than 900 W/m², which can reach a maximum of 1200 W/m² for most of the year. Traditionally water is pumped through the collector at an optimum flow rate, for the extraction of solar thermal energy. If the outlet temperature of the water is high, further circulation of the water through the collector is useless. This is due to the low thermal conductivity of water of 0.6 W/m.K compared to metals which is many orders higher. Hence it is necessary to reduce the surface temperature either by pumping water at a higher flow rate or by enhancing the fluid’s properties by the dispersion of nanoparticles. Pumping water at higher flow rates is not advantageous as the overall efficiency of the system is lowered. Liquids in which nanosized particles of metal or their oxides are dispersed in a base liquid such as water are known as 'Nanofluids'. This results in higher values of thermal conductivity compared to the base liquid. The thermal conductivity increases with the concentration and temperature of the nanofluid. The increase in thermal conductivity with temperature is advantageous for application in collectors as the solar insolation varies throughout the day, with a minimum in the morning reaching a maximum at 2.00p.m and reducing thereafter. The efficiency of the collector estimated using a TiO2 nanofluid of 0.3% concentration is about 0.73, compared to water which is about 0.58. The efficiency is enhanced by 16.7% maximum with 30–50nm sized TiO2 nanoparticles dispersed in the water, compared to the system working solely with water. The flow rate is fixed at 2.7 liters per minute for both liquids.

  15. Eddy-Current Testing of Finned Fuel Cladding

    International Nuclear Information System (INIS)

    Eddy-current methods of testing reactor-fuel components are well established. The literature, however, mainly describes tests which are applied to simple geometries such as cylindrical rods or tubes. Recent AECL fuel designs have called for cladding with heat transfer or locating fins along the length of the fuel. This paper describes the application of eddy-current techniques to three such designs. The function and geometry of the fins must be considered in the selection of the optimum test parameters and the most suitable test coil geometry. Thus, the presence of fins may limit or restrict the test but they will not prevent a successful test. Where the fin geometry is complex eddy currents may well be the most suitable of the non-destructive methods which can be used for flaw detection. The thickness of aluminium cladding over a uranium core is measured with a small probe coil placed between the fins and shielded from them. Two flaw detection tests are described, one on sintered aluminium product (SAP) tubing using an internal bobbin coil and the other on an aluminium-clad uranium-aluminium alloy rod with an external encircling coil. The instrumentation described is relatively simple. A small portable instrument was designed for the cladding thickness measurement. For flaw detection a standard oscilloscope with a plug-in carrier-amplifier module provides a means of sensing and displaying the test coil impedance variations. This equipment ,although it does not permithis equipment ,although it does not permit sophisticated methods of eliminating unwanted noise is adequate for a variety of testing applications and has been specified for routine fuel testing on a production basis. (author)

  16. Experimental investigations on the characteristics of melting processes of stearic acid in an annulus and its thermal conductivity enhancement by fins

    International Nuclear Information System (INIS)

    An experimental rig was set up to study the performance of a thermal storage unit using stearic acid as the heat storage medium. The unit mainly consists of an electrical heating rod and an outer tube, and the space between is an annulus that is filled with stearic acid. The thermal performance of the unit is measured, and the heat transfer characteristics of the melting processes of stearic acid are studied under different heat flux conditions to determine the influence of heat flux on the melting processes. A new type of fin is designed and fixed to the electrical heating rod to enhance the thermal response of the stearic acid. The experimental results show that the fin can improve the heat transfer of the melting process of the thermal storage unit greatly. The equivalent thermal conductivity of the PCM can be augmented by a factor up to 3. The analysis of the experimental results shows that the enhancement mechanism of the fin is attributed to its ability to improve both heat conduction and natural convection very effectively. The influences of the fin size and pitch on the enhancement are also studied and analyzed and it is found that these two parameters can both affect the thermal conductivity enhancement significantly

  17. Flow patterns and heat transfer coefficients in flow-boiling and convective condensation of R22 inside a micro fin of new design

    International Nuclear Information System (INIS)

    Saturated flow boiling and convective condensation experiments for oil-free refrigerant R22 been carried out with a micro fin tube of new design and with a smooth tube. Both tube have the same outer diameter of 9.52 mm and are horizontally operated. Two-phase flow pattern data have been obtained in addition of heat transfer coefficient and pressure drops; more-over, adiabatic tests have been also performed in order for flow pattern map to cover even adiabatic flows. Data are for mass fluxes ranging from about 90 to 400 Kg/s m2. In boiling tests, the nominal saturation temperature is 5 degree C, with inlet quality varying from 0.2 to 0.6 and the quality change ranging from 0.1 to 0.5. In condensation, results are for saturation temperature equal to 35 degree C, with inlet quality between 0.8 and 0.4, and quality change within 0.6 and 0.2. The comparison shows a large heat transfer augmentation with a moderate increment of pressure drops, especially in evaporation were the enhancement factor comes up to 4 while the penalty factor is about 1.4 at the most. Heat transfer coefficients both in evaporation and condensation are compared to the predictions of some recent correlations specifically proposed or modified for micro fin tube

  18. Stress analysis of plate-fin structures in recuperator

    International Nuclear Information System (INIS)

    A high performance compact recuperator with 95% effectiveness is required to achieve a high thermal efficiency power generation of up to 50% in High Temperature Gas Cooled Reactor (HTGR) coupled with closed cycle helium gas turbine. Though a plate-fin type heat exchanger is proposed for this recuperator, much research and development works are needed to establish this high performance goal since there exists no state-of-the-art technology in such a high pressure and high temperature one. One of the important works is to establish the structural analysis and evaluation method in this plate-fin type heat exchanger. This paper describes the results of stress analysis of the plate-fin structure under the internal pressure as the first step of this work. First, the modeling of a unit plate-fin structure for the analysis was examined and a three layers model was confirmed to be most adequate. The stress distribution within the structure was clarified by using this model. Second, the three layers model was simplified to one layer model with sufficient accuracy. By using this model, both the effects of an inclined angle of fin and a thickness of separate on the strength were examined parametrically. Under the relevant design conditions, it was revealed that the optimum inclined angle of fin locates in the neighborhood of 76 degree rather than most difficult fabrication angle 90 degree and there is possibility to adopt thinner thickness than 0.5 mm in the current design. (author)

  19. Slow scan SEC vidicon system. [Secondary Electron Conduction camera tube performance

    Science.gov (United States)

    Chiu, H.-Y.

    1977-01-01

    A slow scan SEC vidicon system is described here. This system is coupled to the 152.4-cm (60-in) McMath telescope at Kitt Peak National Observatory. An anamorphic lens system is used to couple optically the vertical spectrograph to the vidicon system. The resolutin of the over-all system is 55 mA, while the resolution of the spectrograph alone is 50 mA. Actual observational results are used to evaluate the system performance.

  20. Experimental investigation of the higher coefficient of thermal performance for water-in-glass evacuated tube solar water heaters in China

    International Nuclear Information System (INIS)

    Highlights: • The energy grades system for solar water heater (SWH) in China was introduced. • Heat loss and capacity of heat collection mainly affected SWH thermal performance. • Optimum ratio of tank volume to collector area for solar water heater is 57 to 72 L/m2. • The recommendation polyurethane insulation layer should be around 50 mm thick. • SWH with shorter tube has a better thermal performance. - Abstract: Solar water heaters (SWHs), now widely used in China, represent an environmentally friendly way to heat water. We tested the performance of more than 1000 water-in-glass evacuated tube SWHs according to Chinese standards and found that the heat loss from the storage tank and capacity of the solar collector affected their thermal performance. The optimum parameters to maximize the performance of water-in-glass evacuated tube SWHs included a ratio of tank volume to collector area of 57–72 L/m2, which should give a system efficiency of 0.49–0.57, meaning that the temperature of water in the tank will exceed 45 °C after one day of heat collection. In addition, the polyurethane insulation layer should be around 50 mm thick with a free foaming density of about 35 kg/m3, and the evacuated tube should be short. The tilt angle did not affect the performance of the SWHs. These results should aid in the design of highly efficient SWHs

  1. Comparative Performance of the Photomultiplier Tube and the Silicon Avalanche Photodiode When Used as Detectors in Angular Scattering Measurements

    Science.gov (United States)

    Kroner, D. O.; Nelson, R. M.; Boryta, M. D.; Hapke, B. W.; Manatt, K.; Smythe, W. D.

    2014-12-01

    We report the results of a comparative study of two types of photometric detectors that are commonly used for, spacecraft, ground-based telescope, and laboratory observations in support of precise angular scattering investigations of the type described in a companion paper (Nelson et al., this meeting). The performance of the state of the art Hamamatsu C12703-01 Silicon Avalanche photodiode (SAD) was compared to that of the Hamamatsu R928 Photomultiplier tube (PMT). The Hamamatsu R928 evolved from a sequence of photometric detectors with a long history of use in support of laboratory and remote sensing studies, tracing backwards to include the RCA 1P21 and the RCA 931A. Two newly acquired SADs were bench tested along with a new R928 photomultiplier tube that was thermoelectrically cooled to -10 deg C. The SAD's employed electronic thermal compensation supplied by the manufacturer. The SADs and PMT measured electromagnetic radiation from solid-state lasers of wavelength 635 nm after the radiation was reflected from diffusely-scattering surfaces of varying albedos. The SADs were housed on tripods that were co-aligned with the PMT and laser. The photometric detectors were placed 4.3 meters from a reflecting disk. The disk was rotated to reduce the effect of laser speckle. All detectors in the experiment were equipped with notch filters that transmit light only of the wavelength emitted by the laser. Three SR830 DSP Lock-in Amplifiers were connected to the detectors and various setting configurations were compared in order to optimize signal to noise. Neutral Density filters (ND 0,3 and ND 0,9) were placed in the light path to determine the linearity in the response function of the detectors. We conclude that in this application SADs and PMTs produce comparable photometric precision and fidelity. SADs offer greater convenience because thermal compensation circuitry is integrated with the detector. This work was partially supported by NASA's Cassini Science Investigation program.

  2. The cooling performance of SiC/water nano fluid during reflood heat transfer in a long vertical tube

    International Nuclear Information System (INIS)

    Many researchers have been trying to create new kinds of heat transfer fluids in order to enhance the heat transfer performance of the base fluids. Nano fluids as new kinds of heat transfer fluids are a new class of nano technology based heat transfer fluids engineered by dispersing nanoparticles into conventional heat transfer fluids such as water, ethylene glycol, and engine oil. Most of the studies on a heat transfer of nano fluids have been concentrated on the nucleate boiling region and the C HF phenomenon. A quenching phenomenon is important for analysis of the reflood phase associated with the emergency cooling in water cooled nuclear reactor core under a loss of coolant accident and the reflood is happened when water refills the reactor vessel and quenches the fuel rod at the time of the severe accident in nuclear power plant. The use of other fluids instead of water for the quenching experiment in the sphere and rod let specimens has been investigated by many researchers. In this work, we have observed a quenching phenomenon of a hot vertical tube during a reflood using SiC/water nano fluid as a coolant, instead of water. Experiments were conducted to investigate the effect of SiC/water nano fluid on reflood heat transfer in a long vertical tube. The cause selecting SiC nanoparticles is that applying SiC as a cladding material for a light water nuclear reactor is considering because the resistance of SiC to the high-temperature and high radiation environment emperature and high radiation environment is good. 0.01 volume fraction (%) SiC/water nano fluid was prepared by two step method

  3. Method of making heat transfer tube with improved outside surface for nucleate boiling

    International Nuclear Information System (INIS)

    This patent describes a process for making a heat transfer tube with an improved outside surface for nucleate boiling comprising the steps of finning the tube to produce helical fins thereon, forming transverse grooves around the periphery of each fin, and progressively compressing the tips of the grooved fins to cause them to become flattened and of a width in an axial direction which is slightly less than their pitch, thereby defining a narrow opening between fins which is communication with a rather large cavity defined by the sides of adjacent fins in the region under the flattened fin tips. The improvement is described wherein the tips are variably compressed so that the width of the narrow openings adjacent fins is varied so as to produce a range of opening widths which is both larger and smaller than the optimum minimum pore size for nucleate boiling of a particular fluid under a particular set of operating conditions

  4. Influence of the velocity field at the inlet of a Francis turbine draft tube on performance over an operating range

    International Nuclear Information System (INIS)

    We evaluate the sensitivity of the draft tube losses to the velocity field entering a given Francis turbine draft tube while this turbine is operated within a range of discharge values including part-load and full-load regimes. Within the present methodology, the velocity field at the draft tube inlet is determined prior knowing the runner by solving a variational problem for the kinematically constrained swirling flow.

  5. Performance of an alpha-vane and pitot tube in simulated heavy rain environment

    Science.gov (United States)

    Luers, J. K.; Fiscus, I. B.

    1985-01-01

    Experimental tests were conducted in the UDRI Environmental Wind/Rain Tunnel to establish the performance of an alpha-vane, that measures angle of attack, in a simulated heavy rain environment. The tests consisted of emersing the alpha-vane in an airstream with a concurrent water spray penetrating vertically through the airstream. The direction of the spray was varied to make an angle of 5.8 to 18 deg with the airstream direction in order to simulate the conditions that occur when an aircraft lands in a heavy rain environment. Rainrates simulated varied from 1000 to 1200 mm/hr which are the most severe ever expected to be encountered by an aircraft over even a 30 second period. Tunnel airspeeds ranged from 85 to 125 miles per hour. The results showed that even the most severe rainrates produced a misalignment in the alpha-vane of only 1 deg away from the airstream direction. Thus for normal rain conditions experienced by landing aircraft no significant deterioration in alpha-vane performance is expected.

  6. Long term performance of radial shielding subassemblies with zirconium hydride in sodium cooled fast reactor core. Hydrogen release into primary coolant and helium production in cladding tube steels

    International Nuclear Information System (INIS)

    Logn term performance of radial shielding subassemblies with zirconium hydride, which is one of the key technologies to reduce reactor vessel radius, was evaluated for the demonstration fast breeder reactor core. Hydrogen permeation through cladding tube wall and release into primary coolant is essential to design cold traps and shielding performance. Also, higher thermal neutron fluence produces larger helium in cladding tube steels, and may degrade mechanical properties and dimensional stability. A new model was established to quantitatively calculate hydrogen release and helium production under steep gradient of neutron and gamma ray fluxes in outer core region. Austenitic stainless steel (PNC316) and ferritic/martensitic steel (PNC-FMS) will not be capable for 60 years because of large helium production and high permeability, respectively. In contrast, dual wall tube combining PNC-FMS with surface oxidized Fe-18Cr-2Al alloy will be applicable for 60 years in case that manufacturing process is successfully developed. (author)

  7. Numerical Study of CNT Micro Fin Array for Cooling Application

    Directory of Open Access Journals (Sweden)

    Sajjad Nabizadeh

    2013-12-01

    Full Text Available Heat removing from a microelectronic chip packaging has grand effect on performance and durability of the chip. Today’s microchips with high power densities would require efficient methods of cooling. Recently, vertical alignment CNTs, due to their superior thermal, electrical and mechanical properties, was suggested as an effective micro cooler on the level of modern electronics demands. In this paper, the cooling performance of the CNT fin structures is studied numerically. Flow of air was considered as the working fluid flow. CFD simulations have been carried out for a series of CNT micro-fin cooling architectures based on one and two dimensional fin array models. The modeling results indicate that fluid speed is the key factor in heat transfer capacity of the device. Also, the results of 2D carbon nanotube fin array model show more precise and greater thermal performance than that of 1D model. Finally, the examination of pressure drop between inlet and outlet of the cooling device is presented as an important factor which could limit the fluid speed and fin height effect on heat sink performance also investigated.

  8. Numerical Study of CNT Micro Fin Array for Cooling Application

    Directory of Open Access Journals (Sweden)

    Sajjad Nabizadeh

    2013-12-01

    Full Text Available Heat removing from a microelectronic chip packaging has grand effect on performance and durability of the chip. Today’s microchips with high power densities would require efficient methods of cooling. Recently, vertical alignment CNTs, due to their superior thermal, electrical and mechanical properties, was suggested as an effective micro cooler on the level of modern electronics demands. In this paper, the cooling performance of the CNT fin structures is studied numerically. Flow of air was considered as the working fluid flow. CFD simulations have been carried out for a series of CNT micro-fin cooling architectures based on one and two dimensional fin array models. The modeling results indicate that fluid speed is the key factor in heat transfer capacity of the device. Also, the results of 2D carbon nanotube fin array model show more precise and greater thermal performance than that of 1D model. Finally, the examination of pressure drop between inlet and outlet of the cooling device is presented as an important factor which could limit the fluid speed and fin height effect on heat sink performance also investigated.

  9. A comparison of heat transfer enhancement in medium temperature thermal energy storage heat exchanger using fins and multitubes

    Energy Technology Data Exchange (ETDEWEB)

    Agyenim, Francis [Welsh School of Architecture, Cardiff Univ., Wales (United Kingdom); Eames, Philip [School of Engineering, Univ. of Warwick, Coventry (United Kingdom); Smyth, Mervyn [Centre for Sustainable Technologies, Univ. of Ulster, Newtownabbey (United Kingdom)

    2008-07-01

    Experimental studies using a medium temperature phase change material (PCM) Erythritol, melting point 117.7 C, in a horizontal shell and tube system have been undertaken. The experimental programme investigated the suitability of Erythritol (a sugar based material) to deliver a near constant thermal energy to be used for the hot side of LiBr/water absorption cooling system. Four experimental configurations, consisting a base model with no heat enhancement (control system), systems enhanced with circular and longitudinal fins and a multitube system were studied. Experiments were conducted at the same inlet heat transfer fluid temperature of 140 C and mass flow rate of 30 kg min{sup 1} for the different configurations. The results presented include experimentally determined isotherm plots for the final melt illustrating the heat transfer characteristics of the systems and quantitative information relating to the transient change in temperature during the charging and discharging processes. The experimental results indicate that the multitube system achieved the best charging performance with the shortest melt time due to the presence of convection but showed large subcooling during the discharge process. The presence of longitudinal fins improved the conduction heat transfer significantly during the charging process due to increased heat transfer surface area and also reduced the level of subcooling during the discharge process. The circular finned system showed no significant improvement in melt time and size and as such would not be worthy of further development. (orig.)

  10. Pulse Tube Refrigerator

    Science.gov (United States)

    Matsubara, Yoichi

    The pulse tube refrigerator is one of the regenerative cycle refrigerators such as Stirling cycle or Gifford-McMahon cycle which gives the cooling temperature below 150 K down to liquid helium temperature. In 1963, W. E. Gifford invented a simple refrigeration cycle which is composed of compressor, regenerator and simple tube named as pulse tube which gives a similar function of the expander in Stirling or Gifford-McMahon cycle. The thermodynamically performance of this pulse tube refrigerator is inferior to that of other regenerative cycles. In 1984, however, Mikulin and coworkers made a significant advance in pulse tube configuration called as orifice pulse tube. After this, several modifications of the pulse tube hot end configuration have been developed. With those modifications, the thermodynamic performance of the pulse tube refrigerator became the same order to that of Stirling and Gifford-McMahon refrigerator. This article reviews the brief history of the pulse tube refrigerator development in the view point of its thermodynamically efficiency. Simplified theories of the energy flow in the pulse tube have also been described.

  11. Experimental investigation of the effects of length to diameter ratio and nozzle number on the performance of counter flow Ranque-Hilsch vortex tubes

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, K. [Selcuk University, Department of Mechanical Engineering, Faculty of Engineering and Architecture, Konya (Turkey); Baskaya, S. [Gazi University, Department of Mechanical Engineering, Faculty of Engineering and Architecture, Maltepe, Ankara (Turkey); Uysal, B.Z. [Gazi University, Department of Chemical Engineering, Faculty of Engineering and Architecture, Maltepe, Ankara (Turkey)

    2008-01-15

    In this experimental study, performance of counter flow type Ranque-Hilsch vortex tubes (RHVT), with a length to diameter ratio of 10, 15 and 18, were investigated with 2, 4, 6 nozzles. The measure of performance was chosen as the difference between the temperatures of hot output stream and cold output stream. The performances of RHVTs were experimentally tested by making use of velocity and temperature measurements of the input and output streams. It was determined that the difference between the temperatures of these streams, changed between 9 and 56 K. When all the results were assessed, it was concluded that the best performance was obtained when the ratio of vortex tube's length to the diameter was 15 and the nozzle number was at least four, and the inlet pressure was as high as possible. Desired performance could be obtained by controlling the rate of the hot output stream. (orig.)

  12. Experimental investigation and thermodynamic performance analysis of a solar dryer using an evacuated-tube air collector

    International Nuclear Information System (INIS)

    Highlights: ? We evaluate an evacuated-tube solar air collector and use it to develop a novel dryer. ? Apple, carrot and apricot thin-layer drying experiments are conducted. ? Best overall fitting among several available thin-layer drying models is pursued. ? Thermodynamic analysis yields optimal collector area, energy utilization/exergy loss. ? The proposed dryer has a capacity for drying larger quantities of products. -- Abstract: The present work presents a thermodynamic performance analysis of a solar dryer with an evacuated-tube collector. Drying experiments for apples, carrots and apricots were conducted, after a preliminary stage of the investigation which included measurements for the determination of the collector efficiency. These results showed that the warm outlet air of the collector attains temperature levels suitable for drying of agricultural products without the need of preheating. Thus, the present collector was used as the heat source for a drying chamber in the frame of the development of a novel, convective, indirect solar dryer; given the fact that in the literature there are only a few studies about this type of collectors in conjunction with solar drying applications. Thin-layer drying models were fitted to the experimental drying curves, including the recent model of Diamante et al. which showed good correlation coefficients for all the tested products. Drying parameters such as moisture ratio and drying rates were calculated. Furthermore, an energetic/exergetic analysis of the dryer was also conducted and performance coefficients such as pick-up and exergy efficiencies, energy utilization ratio, exergy losses were determined for several configurations such as single and double-trays and several drying air velocities. On the other hand, an optimal collector surface area study was conducted, based on laws for minimum entropy generation. Design parameters such as optimum collector area were determined based on the minimum entropy generation number. The mass flow number, along with the maximum collector and fluid exit temperatures were studied in relation to the minimum entropy generation. The energy/exergy analysis proposed, provides a useful tool for the evaluation of this type of collectors regarding their effectiveness as part of a solar drying system. Moreover, the results of the present study showed that the proposed solar dryer has a capacity for drying larger quantities of the products than those considered (in the frame of the experimental study) given the high efficiency of the collector. In general, the proposed system provides an interesting option for the penetration of this type of collectors in large-scale applications in the agricultural and industrial sector.

  13. QuantiFERON®-TB gold in-tube performance for diagnosing active tuberculosis in children and adults in a high burden setting

    DEFF Research Database (Denmark)

    Rose, Michala Vaaben; Kimaro, Godfather

    2012-01-01

    To determine whether QuantiFERON®-TB Gold In-Tube (QFT) can contribute to the diagnosis of active tuberculosis (TB) in children in a high-burden setting and to assess the performance of QFT and tuberculin skin test (TST) in a prospective cohort of TB suspect children compared to adults with confirmed TB in Tanzania.

  14. Dynamics of tubes in fluid with tube-baffle interaction

    International Nuclear Information System (INIS)

    Three series of tests are performed to evaluate the effects of tube to tube-support-plate (TSP) clearance on tube dynamic characteristics and instability phenomena for tube arrays in crossflow. Test results show that, for relatively large clearances, tubes may possess TSP-inactive modes in which the tubes rattle inside some of the tube-support-plate holes, and that the natural frequencies of TSP-inactive modes are lower than those of TSP-active modes, in which the support plates provide knife-edge type support. Tube response characteristics associated with TSP-inactive modes are sensitive to tube-to-TSP clearance, TSP thickness, excitation amplitude, tube alignment, and the fluid inside the clearance. In addition, tube response is intrinsically nonlinear, with the dominance of TSP-inactive or TSP-active modes depending on the magnitudes of different system parameters. In general, such a system is difficult to model; only a full-scale test can provide all the necessary characteristics. A tube array supported by TSPs with relatively large clearances may be subjected to dynamic instability in some of the TSP-inactive modes; tube response characteristics and impact forces on TSPs for a tube row are studied in detail in this report. Tube displacements associated with the instability of a TSP-inactive mode are small; however, impacts of the tube against TSPs may result in significant damage in a relatively short time. 52 figures

  15. Performance of multiple mini-tube heat exchangers as an internal heat exchanger of a vapor-injection cycle heat pump

    Science.gov (United States)

    Jang, Jin Yong; Jeong, Ji Hwan

    2015-05-01

    A multiple mini-tube (MMT) heat exchanger was considered as an internal heat exchanger of vapor-injection cycle heat pump. Heat transfer and pressure drop in multiple mini-tube heat exchangers were numerically and experimentally investigated. Results show that the best performance of the MMT heat exchanger can be obtained when the intermediate-pressure two-phase refrigerant is supplied to the shell-side and this refrigerant reaches a saturated vapor state at the exit of the heat exchanger.

  16. Performance Analysis of a Shell Tube Condenser for a Model Organic Rankine Cycle for Use in Geothermal Power Plant

    Directory of Open Access Journals (Sweden)

    Haile Araya Nigusse

    2014-08-01

    Full Text Available The global energy demand increases with the economic growth and population rise. Most electrical power is currently generated by conventional methods from fossil fuels. Despite the high energy demand, the conventional energy resources such as fossil fuels have been declining. In addition to this harmful combustion byproducts are resulting global warming. However, the increase of environmental concerns and energy crisis can be minimized by sustainable utilization of the low to medium temperature heat resources. The Organic Rankine Cycle power plant is a very effective option for utilization of low grade heat sources for power generation. Heat exchangers are the main components of the Organic Rankine Cycle power plant which receives heat energy from the heat source to evaporate and condense the low boiling temperature organic working fluid which in turn drives the turbine to generate power. This paper presents a simplified approach to the design, fabrication and performance assessment of a shell tube heat exchanger designed for condenser in a model Organic Rankine Cycle geothermal power plant. The design involved sizing of heat exchanger (condenser using the LMTD method based on an expected heat transfer rate. The heat exchanger of the model power plant was tested in which hot water simulated geothermal brine. The results of the experiment indicated that the heat exchanger is thermally suitable for the condenser of the model power plant.

  17. Modeling of heating and cooling performance of counter flow type vortex tube by using artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    Kocabas, Fikret [Bartin University, Faculty of Engineering, Civil Engineering Department, Bartin (Turkey); Korkmaz, Murat [Hacettepe University, Vocational High School, Department of Machinery, Polatli, Ankara (Turkey); Sorgucu, Ugur [Bartin University, Faculty of Engineering, Electrical and Electronics Engineering Department, Bartin (Turkey); Donmez, Senayi [Karatekin University Technical and Business College, Civil Engineering Department, Cankiri (Turkey)

    2010-08-15

    In this study, the effect of the nozzle number and the inlet pressures, which vary from 150 to 700 kPa with 50 kPa increments, on the heating and cooling performance of the counter flow type vortex tube has been modeled with an artificial neural network (ANN) and multi-linear regression (MLR) models by using the experimentally obtained data. In the developed system output parameter temperature gradiant between the cold and hot outlets ({delta}T) has been determined using inlet parameters such as the inlet pressure (P{sub inlet}), nozzle number (N), cold mass fraction ({mu}{sub c}) and inlet mass flow rate (m{sub inlet}). The back-propagation learning algorithm with variant which is Levenberg-Marquardt (LM) and Sigmoid transfer function have been used in the network. In addition, the statistical validity of the developed model has been determined by using the coefficient of determination (R{sup 2}), the root means square error (RMSE), and the relative absolute errors (RAE). R{sup 2}, RMSE and RAE have been determined for {delta}T as 0.9989, 0.5016, 0.0540 respectively. (author)

  18. Performance of a 4 Kelvin pulse-tube cooled cryostat with dc SQUID amplifiers for bolometric detector testing

    CERN Document Server

    Barron, Darcy; Keating, Brian; Quillin, Ron; Stebor, Nathan; Wilson, Brandon

    2013-01-01

    The latest generation of cosmic microwave background (CMB) telescopes is searching for the undetected faint signature of gravitational waves from inflation in the polarized signal of the CMB. To achieve the unprecedented levels of sensitivity required, these experiments use arrays of superconducting Transition Edge Sensor (TES) bolometers that are cooled to sub-Kelvin temperatures for photon-noise limited performance. These TES detectors are read out using low- noise SQUID amplifiers. To rapidly test these detectors and similar devices in a laboratory setting, we constructed a cryogenic refrigeration chain consisting of a commercial two-stage pulse-tube cooler, with a base temperature of 3 K, and a closed-cycle 3He/4He/3He sorption cooler, with a base temperature of 220 mK. A commercial dc SQUID system, with sensors cooled to 4 K, was used as a highly-sensitive cryogenic ammeter. Due to the extreme sensitivity of SQUIDs to changing magnetic fields, there are several challenges involving cooling them with puls...

  19. Experimental investigation of the performance of a Ranque-Hilsch vortex tube with regard to a plug located at the hot outlet

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, K. [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Selcuk University, Konya (Turkey); Baskaya, S. [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Gazi University, Maltepe, 06570 Ankara (Turkey); Uysal, B.Z. [Department of Chemical Engineering, Faculty of Engineering and Architecture, Gazi University, Maltepe, Ankara (Turkey); Ucgul, I. [Department of Textile Engineering, Faculty of Engineering and Architecture, Suleyman Demirel University, Isparta (Turkey)

    2009-01-15

    In this study, effects of position, diameter (5, 6, 7, 8 mm) and angle (30 -180 ) of a mobile plug, located at the hot outlet side in a Ranque-Hilsch Vortex Tube (RHVT), were determined experimentally for best performance. In addition to plug parameters, effects of supply pressure (200-420 kPa) and number of nozzles (2, 4, 6) were also studied. The internal diameter (D) of the vortex tube used in the experiments was 9 mm; the ratio of the length of the vortex tube to its diameter (L/D) was 15. Four different plug locations were studied. The maximum difference in the temperatures of hot and cold streams was obtained for the plug diameter of 5 mm, tip angles of 30 and 60 , 4 nozzles and by keeping the plug location at the far extreme end. (author)

  20. Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

    DEFF Research Database (Denmark)

    Aabye, Martine G; Hermansen, Thomas Stig

    2012-01-01

    ABSTRACT: BACKGROUND: False negative and indeterminate Interferon Gamma Release Assay (IGRA) results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB) and to impair Interferon-gamma (IFN-gamma) responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively. METHODS: Patients with confirmed TB from Denmark (DK, n = 34; 20 smokers) and Tanzania (TZ, n = 172; 23 smokers) were tested with the QuantiFERON-TB Gold In tube (QFT). Median IFN-gamma level in smokers and non smokers were compared and smoking was analysed as a risk factor for false negative and indeterminate QFT results. RESULTS: Smokers from both DK and TZ had lower IFN-gamma antigen responses (median 0.9 vs. 4.2 IU/ml, p = 0.04 and 0.4 vs. 1.6, p <0.01), less positive (50 vs. 86%, p = 0.03 and 48 vs. 75%, p <0.01) and more false negative (45 vs. 0%, p <0.01 and 26 vs. 11%, p = 0.04) QFT results. In Tanzanian patients, logistic regression analysis adjusted for sex, age, HIV and alcohol consumption showed an association of smoking with false negative (OR 17.1, CI: 3.0-99.1, p <0.01) and indeterminate QFT results (OR 5.1, CI: 1.2-21.3, p = 0.02). CONCLUSIONS: Cigarette smoking was associated with false negative and indeterminate IGRA results in both a high and a low TB endemic setting independent of HIV status.

  1. Optimization of “T”-Shaped Fins Geometry Using Constructal Theory and “FEA” Concepts

    Directory of Open Access Journals (Sweden)

    ManasRanjanPadhy

    2014-12-01

    Full Text Available This paper reports the geometric (constructal optimization of T-shaped fin assemblies, where the objective is to maximize the global thermal conductance of the assembly, subject to total volume and fin-material constraints. Assemblies of plate fins are considered. It is shown that every geometric feature of the assembly is delivered by the optimization principle and the constraints. These optimal features are reported in dimensionless terms for this entire class of fin assemblies. Based on the constructal theory by Dr. A Bejan, T-shaped fins are developed for better heat conductance as compared to conventional fins. Now the geometry of this T type of fin contains many geometry parameters which affect the overall conductance of the fin. With the same material constraint and volume constraints optimal geometry ratios has been calculated so as to design the fin for its best performance. With focus to the practical situations and heat flow patterns, it is quite complex to calculate the temperatures on a T-shaped fin. It requires the help of FEA concepts and CAE software to optimize the geometry.

  2. Optimal design of plate-fin heat exchangers by a Bees Algorithm

    International Nuclear Information System (INIS)

    In this study, the application of Bees Algorithm (BA) in the optimum design of a cross flow plate-fin heat exchanger with offset strip fin is investigated. First, heat exchanger is optimized and designed according to the effectiveness optimization. Then, an analysis based on the second law of thermodynamics and minimizations of entropy generation units is performed. Specific heat duty, space restriction and permitted pressure drop are considered as the constraints for maximizing the effectiveness and minimizing the entropy generation units. Hot and cold flow length of the heat exchangers, number of fin layers, fin frequency, fin height, fin strip length and fin thickness are introduced as optimization variables. The effectiveness and accuracy of the suggested algorithm are compared with literature. The results have shown that BA can find optimum configuration with higher accuracy in comparison with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Imperialist Competitive Algorithm (ICA) and preliminary design. - Highlights: •We analyzed a plate-fin heat exchanger with offset strip fins. •This is the first application of a Bees Algorithm for plate-fin heat exchanger design. •Preliminarily design and effectiveness of PFHE was improved by minimizing the entropy generation units. •The results show the superiority of this method over GA, PSO and ICA and preliminary design

  3. Boiling heat transfer from an excavated fin

    Science.gov (United States)

    Liaw, S. P.; Yeh, R. H.

    1992-04-01

    A single pin fin with excavation at base is proposed to enhance boiling heat transfer. The temperature distribution in the fin is obtained numerically by solving a 2D heat conduction equation. A copper fin boiling in isopropyl alcohol is taken as an example. When the operating temperature exceeds a specific value, the heat duty decreases drastically, and the whole fin is governed by film boiling. This highest operating temperature limit is raised by digging a hole at the fin base. Two distinct solutions are found by using different initial guesses into the code. This hysteresis effect becomes noticeable for a bigger hole. A model is also developed to predict the burnout temperatures.

  4. ENERGY PERFORMANCE IMPROVEMENT, FLOW BEHAVIOR AND HEAT TRANSFER INVESTIGATION IN A CIRCULAR TUBE WITH V-DOWNSTREAM DISCRETE BAFFLES

    OpenAIRE

    Withada Jedsadaratanachai; Amnart Boonloi

    2013-01-01

    A mathematical study has been carried out to examine periodic laminar flow and heat transfer characteristics in a three-dimensional isothermal wall circular tube with 45° in-line V-discrete baffles. The computations are based on the Finite Volume Method (FVM) and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the diameter of the circular tube ranging from 100 to 1200. To generate main streamwise vortex f...

  5. Collector Efficiency in Downward-Type Internal-Recycle Solar Air Heaters with Attached Fins

    Directory of Open Access Journals (Sweden)

    Chii-Dong Ho

    2013-10-01

    Full Text Available The internal-recycle operation effect on collector efficiency in downward-type rectangular solar air heaters with attached fins is theoretically investigated. It is found that considerable collector efficiency is obtainable if the collector has attached fins and the operation is carried out with internal recycling. The recycling operation increases the fluid velocity to decrease the heat transfer resistance, compensating for the undesirable effect of decreasing the heat transfer driving force (temperature difference due to remixing. The attached fins provide an enlarged heat transfer area. The order of performance in a device of same size is: double pass with recycle and fins > double pass with recycle but without fins > single pass without recycle and fins.

  6. Thermohydraulic analysis of smooth and finned annular ducts

    International Nuclear Information System (INIS)

    The present work is concerned with the turbulent heat transfer and pressure drop in smooth and finned annular ducts overage heat transfer coefficients have been obtained by means of the heat exchanger theory. In addition, friction factors have also been determined. The experiments were performed by utilizing four double-pipe heat exchangers. The flowing fluids, in the heat exchangers, were air and water. The average heat transfer coefficients, for air flowing in the annular section, were determined by measuring the overall heat transfer coefficients of the heat exchangers. In order to attain fully developed conditions, the heat exchangers had a starting length of 30 hydraulic diameters. The thermal boundary conditions consisted of uniform temperature on the inner surface, the outer surface being insulated. The heat transfer coefficients and friction factors are presented in dimensionaless forms, as functions of the Reynolds number of the flow. The results for the smooth and finned annular ducts were compared. The purpose of such comparison was to study the influence of the fins on the pressure drop and heat transfer rate. In the case of the finned nular ducts, it is shown that the fin efficiency has some fluence on the heat transfer rates. The, a two-dimensional at transfer analysis was performed in order to obtain the n efficiency and the annular region efficiency. It is also shown that the overall thermal performance of finned surfaces epends mainly on the Nusselt number and on the region eficiency. These parameters are presented as functions of the Reynolds number of the flow and the geometry of the problem. (author)

  7. Characteristics of a micro-fin evaporator: Theoretical analysis and experimental verification

    Directory of Open Access Journals (Sweden)

    Zheng Hui-Fan

    2013-01-01

    Full Text Available A theoretical analysis and experimental verification on the characteristics of a micro-fin evaporator using R290 and R717 as refrigerants were carried out. The heat capacity and heat transfer coefficient of the micro-fin evaporator were investigated under different water mass flow rate, different refrigerant mass flow rate, and different inner tube diameter of micro-fin evaporator. The simulation results of the heat transfer coefficient are fairly in good agreement with the experimental data. The results show that heat capacity and the heat transfer coefficient of the micro-fin evaporator increase with increasing logarithmic mean temperature difference, the water mass flow rate and the refrigerant mass flow rate. Heat capacity of the micro-fin evaporator for diameter 9.52 mm is higher than that of diameter 7.00 mm with using R290 as refrigerant. Heat capacity of the micro-fin evaporator with using R717 as refrigerant is higher than that of R290 as refrigerant. The results of this study can provide useful guidelines for optimal design and operation of micro-fin evaporator in its present or future applications.

  8. Influence of Chimney Width in Natural Convection Heat Transfer on a Vertical Finned Plate

    International Nuclear Information System (INIS)

    The RCCS adopts the chimney system to increase the flow rate. Also the fins installed in the inner walls of the chimney will provide an additional cooling performance by increasing the heat transfer area. On the other hand, the fins also increase the friction loss i. e. the pressure drop. Thus, in order to improve the heat transfer performance of the RCCS, an optimization among the fin parameters is necessary. Many experimental and numerical studies regarding the fin and the chimney are available. In this study, the natural convection heat transfer of the fin system located inside the chimney was measured. Based on the analogy concept, heat transfer experiments were replaced by mass transfer experiments using a sulfuric acid-copper sulfate (H2SO4-CuSO4) electroplating system. The experiments were conducted by varying fin spacing, fin height, chimney width, and chimney height. This study experimentally investigated the natural convection heat transfer of the vertical finned plate in the chimney. Using an analogy, the heat transfer systems were replaced by mass transfer systems. The measured mass transfer coefficients was the difference with the existing heat transfer correlations due to the large value of the Pr, but exhibited similar trends with the existing heat transfer correlations. The heat transfer rate is increased by the decrease of the fin spacing and the increased fin height due to increased heat transfer area and chimney flow pattern. The chimney effect enhances heat transfer rate of vertical finned plate and the chimney effect on the Nus In this study, the heat transfer rate on vertical finned plate in the chimney was confirmed by experiment for high values of Ra was stronger for the narrow chimney width, and became stronger by the higher chimney. The chimney effect was not observed when the chimney width becomes larger than a certain value depending on the Ras

  9. Wind Tubes

    Science.gov (United States)

    Exploratorium

    2012-12-14

    In this activity, learners create and experiment with wind tubes. These tubes are a playful and inventive way to explore the effect that moving air has on objects. Construction uses everyday materials such as a fan and embroidery hoops. It’s fun to make things fly out of or float in the tubes, and to adjust the tubes to change the way the objects fly. The activity requires a significant amount of time and resources to build and may require adult help in construction. Experimentation with the wind tubes is engaging for a wide age range of learners.

  10. Tracheostomy tubes.

    Science.gov (United States)

    Hess, Dean R; Altobelli, Neila P

    2014-06-01

    Tracheostomy tubes are used to administer positive-pressure ventilation, to provide a patent airway, and to provide access to the lower respiratory tract for airway clearance. They are available in a variety of sizes and styles from several manufacturers. The dimensions of tracheostomy tubes are given by their inner diameter, outer diameter, length, and curvature. Differences in dimensions between tubes with the same inner diameter from different manufacturers are not commonly appreciated but may have important clinical implications. Tracheostomy tubes can be cuffed or uncuffed and may be fenestrated. Some tracheostomy tubes are designed with an inner cannula. It is important for clinicians caring for patients with a tracheostomy tube to appreciate the nuances of various tracheostomy tube designs and to select a tube that appropriately fits the patient. The optimal frequency of changing a chronic tracheostomy tube is controversial. Specialized teams may be useful in managing patients with a tracheostomy. Speech can be facilitated with a speaking valve in patients with a tracheostomy tube who are breathing spontaneously. In mechanically ventilated patients with a tracheostomy, a talking tracheostomy tube, a deflated cuff technique with a speaking valve, or a deflated cuff technique without a speaking valve can be used to facilitate speech. PMID:24891201

  11. ENERGY PERFORMANCE IMPROVEMENT, FLOW BEHAVIOR AND HEAT TRANSFER INVESTIGATION IN A CIRCULAR TUBE WITH V-DOWNSTREAM DISCRETE BAFFLES

    Directory of Open Access Journals (Sweden)

    Withada Jedsadaratanachai

    2013-01-01

    Full Text Available A mathematical study has been carried out to examine periodic laminar flow and heat transfer characteristics in a three-dimensional isothermal wall circular tube with 45° in-line V-discrete baffles. The computations are based on the Finite Volume Method (FVM and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the diameter of the circular tube ranging from 100 to 1200. To generate main streamwise vortex flows through the tested section, V-discrete baffles with an attack angle of 45° are mounted in tandem with in-line arrangement and pointing downstream (V-Downstream inserted in the middle of the tested tube. Effects of different Blockage Ratio (b/D, BR and Pitch Ratio (P/D, PR on heat transfer and pressure drop in the tube are studied. It is apparent that the main vortex flows can induce impinging flows on a wall of the interbaffle cavity leading to extreme increases in heat transfer rate over the circular tube. In addition, the rise in the BR and reduce of PR results in the increase in the Nusselt number and friction factor values. The computational results show that the optimum thermal enhancement factor is around 2.5 at BR = 0.15, PR = 1 and Re = 1200.

  12. Effects of spray axis incident angle on heat transfer performance of rhombus-pitch shell-and-tube interior spray evaporator

    International Nuclear Information System (INIS)

    An interior spray method is proposed for enhancing the heat transfer performance of a compact rhombus-pitch shell-and-tube spray evaporator. The experimental results show that the shell-side heat transfer coefficient obtained using the proposed spray method is significantly higher than that achieved in a conventional flooded-type evaporator. Four different spray axis incident angles (0 .deg., 45 .deg., 60 .deg. and 75 .deg.) are tested in order to investigate the effect of the spray inclination angle on the heat transfer performance of the spray evaporator system. It is shown that the optimal heat transfer performance is obtained using a spray axis incident angle of 60 .deg.

  13. Invariance, Conservation Laws, and Exact Solutions of the Nonlinear Cylindrical Fin Equation

    Science.gov (United States)

    Ali, Saeed M.; Bokhari, Ashfaque H.; Zaman, Fiazuddin D.; Kara, Abdul H.

    2014-06-01

    Fins are heat exchange surfaces which are used widely in industry. The partial differential equation arising from heat transfer in a fin of cylindrical shape with temperature dependent thermal diffusivity are studied. The method of multipliers and invariance of the differential equations is employed to obtain conservation laws and perform double reduction.

  14. Performance comparison between three intraoral image receptors of different technology at a variety of tube potential, tube current and exposure time settings using a stepwedge phantom

    OpenAIRE

    Elli Katsoni; Tsalafoutas, Ioannis A.; Panagiotis Gritzalis; Evripidis Stefanou; Evangelos Georgiou; Emmanuel Yakoumakis

    2011-01-01

    Purpose: To comparatively evaluate the per-formance of three intraoral image receptors of different technology when exposed to different X-ray beam spectra, dose and dose rate levels using a stepwedge phantom. Materials and methods: The intraoral radiographic receptors evaluated were: the Kodak Insight F speed class film, the Kodak RVG 6000, and the Duerr Vis-tascan Combi PSP system. A dental quality control phantom made of Plexiglas, containing an aluminium stepwedge with 12 steps and 7 hole...

  15. Atom-probe for FinFET dopant characterization

    International Nuclear Information System (INIS)

    With the continuous shrinking of transistors and advent of new transistor architectures to keep in pace with Moore's law and ITRS goals, there is a rising interest in multigate 3D-devices like FinFETs where the channel is surrounded by gates on multiple surfaces. The performance of these devices depends on the dimensions and the spatial distribution of dopants in source/drain regions of the device. As a result there is a need for new metrology approach/technique to characterize quantitatively the dopant distribution in these devices with nanometer precision in 3D. In recent years, atom probe tomography (APT) has shown its ability to analyze semiconductor and thin insulator materials effectively with sub-nm resolution in 3D. In this paper we will discuss the methodology used to study FinFET-based structures using APT. Whereas challenges and solutions for sample preparation linked to the limited fin dimensions already have been reported before, we report here an approach to prepare fin structures for APT, which based on their processing history (trenches filled with Si) are in principle invisible in FIB and SEM. Hence alternative solutions in locating and positioning them on the APT-tip are presented. We also report on the use of the atom probe results on FinFETs to understand the role of different dopant implantation angles (10o and 45o) when attempting conformal doping of FinFETs and provide a quantitative comparison with alternative approaches such as 1D secondary ion mass spectrometry (SIMS) and theoretical model values. -- Research highlights: ? This paper provides the information on how to characterize the FinFET devices using atom probe tomography (APT). ? Importance of this work is to assess the performance of these devices at different processing conditions by extracting the compositional profiles. ? The performance of these devices depends on the dimensions and the spatial distribution of dopants in source/drain regions. ? In this publication we reported on the issues involved in probing these devices using APT and how we were able to overcome the few challenges in this regard. ? We also report on the use of the APT results on FinFETs to understand the role of different dopant implantation angles (10o and 45o). ? The quantitative comparison with alternative approaches such as 1D secondary ion mass spectrometry (SIMS) and theoretical model values were presented.

  16. Tube joining

    International Nuclear Information System (INIS)

    The patent deals with the pressure-tight joining of two aluminium tubes in a solder bath, e.g. of a capillary tube, outer diameter 6 mm, as is common in cooling systems, with a stronger standard tube with inner diameter of about 8 mm. In the proposed soldered joint using ultrasonics, trapped air within the ring gap between the tubes to be filled with solder (in the mentioned example 1 mm all round) is avoided. The tubes pushed into one another to a distance of several cm are fixed for a uniform air gap prior to placing in the solder bath. This is done by several beads of the same diameter pressed in from outside. To weld the two tubes, which can no longer move relative to one another, these are vertically immersed in the solder bath until the inner tube, with its tube end pointing upwards, remains above the solder bath level. Hence no solder rising in the gap can get into the inner tube. The outer tube is free from solder in its flow section. The beads do not prevent the penetration of the solder into the gap. (HP)

  17. Studying the effect of the shape parameters on the performance of the darrieus wind turbine using the multiple double disk stream tube theory

    International Nuclear Information System (INIS)

    The performance of the Darrieus vertical axis turbine is comparable with that of the more common horizontal axis machines. It has a number of aerodynamic and structural advantages over HAWTS. However the darrieus turbines are not self-starting at low wind speeds which is a considerable disadvantage for a simple small scale installation. Generally, papers concerning vertical axis turbine do not study the behavior of the rotor at low tip speed ratios. Therefore they do not deal with the self starting problems. A number of analytical methods were investigated to see whether they could predict the starting performance of vertical axis turbines. The chosen methods and 'actuator disc theory' for multiple stream tubes. In this paper the multiple stream tube model is applied using two discs in tandem. The computational analysis of all models simulates the blade aerodynamics throughout the full range of incidence from 180 degree centigrade. The effects of varying various geometric parameters of the windmill upon the performance of the rotor are investigated to find a design with improved self starting characteristics. The best agreement between theory and experiment was obtained using the multiple stream tube (double disc) models.(Author)

  18. Thermal transport in oblique finned microminichannels

    CERN Document Server

    Fan, Yan; Singh, Pawan Kumar; Lee, Yong Jiun

    2015-01-01

    The main aim of this book is to introduce and give an overview of a novel, easy, and highly effective heat transfer augmentation technique for single-phase micro/minichannel heat sink. The specific objectives of the volume are to: Introduce a novel planar oblique fin microchannel and cylindrical oblique fin minichannel heat sink design using passive heat transfer enhancement techniques  Investigate the thermal transport in both planar and cylindrical oblique fin structures through numerical simulation and systematic experimental studies. Evaluate the feasibility of employing the proposed solution in cooling non-uniform heat fluxes and hotspot suppression Conduct the similarity analysis and parametric study to obtain empirical correlations to evaluate the total heat transfer rate of the oblique fin heat sink Investigate the flow mechanism and optimize the dimensions of cylindrical oblique fin heat sink Investigate the influence of edge effect on flow and temperature uniformity in these oblique fin chan...

  19. Thermal-hydraulic performance of an A type air cooled condenser

    International Nuclear Information System (INIS)

    The effects of fin spacing, Re number and transverse tube pitch on a four-row A type air cooled air condenser in staggered arrangements are investigated by 3-D numerical simulations. The steady state is assumed for the numerical simulations, and the standard k-epsilon model is used to perform the simulations. The frontal velocity has been varied from 1 to 12 m/s. The range of Reynolds number is from 3000-40000. The numerical results are validated with the standard correlations. The boundary layer developments and horseshoe vortices between the fins are found to be substantially dependent on the fin spacing and Reynolds number. The heat transfer and pressure drop results are presented for varying fin spacing and Reynolds number. The heat transfer per unit pressure drop is also presented. (author)

  20. Comparison between one-dimensional uncoupled and convection-conduction conjugated approaches in finned surface heat transfer

    Scientific Electronic Library Online (English)

    Cláudia R., Andrade; Edson L., Zaparoli.

    Full Text Available This work studies the forced convection problem in internal flow between concentric annular ducts, with radial fins at the internal tube surface. The finned surface heat transfer is analyzed by two different approaches. In the first one, it is assumed one-dimensional heat conduction along the intern [...] al tube wall and fins, with the convection heat transfer coefficient being a known parameter, determined by an uncoupled solution. In the other way, named conjugated approach, the mathematical model (continuity, momentum, energy and K-epsilon equations) applied to tube annuli problem was numerically solved using finite element technique in a coupled formulation. At first time, a comparison was made between results obtained for the conjugated problem and experimental data, showing good agreement. Then, the temperature profiles under these two approaches were compared to each other to analyze the validity of the one-dimensional classical formulation that has been utilized in the heat exchanger design.

  1. Comparison between one-dimensional uncoupled and convection-conduction conjugated approaches in finned surface heat transfer

    Directory of Open Access Journals (Sweden)

    Andrade Cláudia R.

    2000-01-01

    Full Text Available This work studies the forced convection problem in internal flow between concentric annular ducts, with radial fins at the internal tube surface. The finned surface heat transfer is analyzed by two different approaches. In the first one, it is assumed one-dimensional heat conduction along the internal tube wall and fins, with the convection heat transfer coefficient being a known parameter, determined by an uncoupled solution. In the other way, named conjugated approach, the mathematical model (continuity, momentum, energy and K-epsilon equations applied to tube annuli problem was numerically solved using finite element technique in a coupled formulation. At first time, a comparison was made between results obtained for the conjugated problem and experimental data, showing good agreement. Then, the temperature profiles under these two approaches were compared to each other to analyze the validity of the one-dimensional classical formulation that has been utilized in the heat exchanger design.

  2. Performance test results of mock-up model test facility with a full-scale reaction tube for HTTR hydrogen production system. Contract research

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, Yoshiyuki; Hayashi, Koji; Kato, Michio [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others

    2003-03-01

    Research on a hydrogen production system by steam reforming of methane, chemical reaction; CH{sub 4} + H{sub 2}O {yields} 3H{sub 2}O + CO, has been carried out to couple with the HTTR for establishment of high-temperature nuclear heat utilization technology and contribution to hydrogen energy society in future. The mock-up test facility with a full-scale reaction tube test facility, a model simulating one reaction tube of a steam reformer of the HTTR hydrogen production system in full scale, was fabricated to perform tests on controllability, hydrogen production performance etc. under the same pressure and temperature conditions as those of the HTTR hydrogen production system. The design and fabrication of the test facility started from 1997, and the all components were installed until September in 2001. In a performance test conducted from October in 2001 to February in 2002, performance of each component was examined and hydrogen of 120m{sup 3}{sub N}/h was successfully produced with high-temperature helium gas. This report describes the performance test results on components performance, hydrogen production characteristics etc., and main troubles and countermeasures. (author)

  3. Physical Scaling Limits of FinFET Structure: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Gaurav Saini

    2011-03-01

    Full Text Available In this work an attempt has been made to analyze the scaling limits of Double Gate (DG underlap andTriple Gate (TG overlap FinFET structure using 2D and 3D computer simulations respectively. Toanalyze the scaling limits of FinFET structure, simulations are performed using three variables: finthickness,fin-height and gate-length. From 2D simulation of DG FinFET, it is found that the gate-length(L and fin-thickness (Tfin ratio plays a key role while deciding the performance of the device. DrainInduced Barrier Lowering (DIBL and Subthreshold Swing (SS increase abruptly when (L/Tfin ratio goesbelow 1.5. So, there will be a trade-off in between SCEs and on- current of the device since on-off currentratio is found to be high at small dimensions. From 3D simulation study on TG FinFET, It is found thatboth fin-thickness (Tfin and fin-height (Hfin can control the SCEs. However, Tfin is found to be moredominant parameter than Hfin while deciding the SCEs. DIBL and SS increase as (Leff/Tfin ratiodecreases. The (Leff/Tfin ratio can be reduced below 1.5 unlike DG FinFET for the same SCEs. However,as this ratio approaches to 1, the SCEs can go beyond acceptable limits for TG FinFET structure. Therelative ratio of Hfin and Tfin should be maximum at a given Tfin and Leff to get maximum on-current perunit width. However, increasing Hfin degrades the fin stability and degrades SCEs.

  4. Parameter optimization through performance analysis of model based control of a batch heat treatment furnace with low NO x radiant tube burner

    International Nuclear Information System (INIS)

    A model based control structure for heat treating a 0.5% C steel slab in a batch furnace with low NO x radiant tube burner is designed and tested for performance to yield optimal parameter values using the model developed in the companion paper. Combustion is considered in a highly preheated and product gas diluted mode. Controlled combustion with a proposed arrangement for preheating and diluting the air by recirculating the exhaust gas that can be retrofitted with an existing burner yields satisfactory performance and emission characteristics. Finally, the effect of variable property considerations are presented and critically analyzed

  5. Aluminum fin-stock alloys

    International Nuclear Information System (INIS)

    Aluminum alloys have long been used in the production of heat exchanger fins. The comparative properties of the different alloys used for this purpose has not been an issue in the past, because of the significant thickness of the finstock material. However, in order to make fins lighter in weight, there is a growing demand for thinner finstock materials, which has emphasized the need for improved mechanical properties, thermal conductivity and corrosion resistance. The objective of this project is to determine the effect of iron, silicon and manganese percentage increment on the required mechanical properties for this application by analyzing four different aluminum alloys. The four selected aluminum alloys are 1100, 8011, 8079 and 8150, which are wrought non-heat treatable alloys with different amount of the above elements. Aluminum alloy 1100 serve as a control specimen, as it is commercially pure aluminum. The study also reports the effect of different annealing cycles on the mechanical properties of the selected alloys. Metallographic examination was also preformed to study the effect of annealing on the precipitate phases and the distribution of these phases for each alloy. The microstructure analysis of the aluminum alloys studied indicates that the precipitated phase in the case of aluminum alloys 1100 and 8079 is beta-FeAI3, while in 8011 it is a-alfa AIFeSi, and the aluminum alloy 8150 contains AI6(Mn,Fe) phase. The comparison of aluminum alloys 8011 and 8079omparison of aluminum alloys 8011 and 8079 with aluminum alloy 1100 show that the addition of iron and silicon improves the percent elongation and reduces strength. The manganese addition increases the stability of mechanical properties along the annealing range as shown by the comparison of aluminum alloy 8150 with aluminum alloy 1100. Alloy 8150 show superior properties over the other alloys due to the reaction of iron and manganese, resulting in a preferable response to thermal treatment and improved mechanical properties. (author)

  6. Percutaneous gastrostomy performed by radiologists using balloon replacement tubes. A simple interventional technique for the placement of nutritional catheters without endoscopy or surgery

    International Nuclear Information System (INIS)

    Patients afflicted with stenotic head and neck or esophageal tumors often require artificial enteral feeding. Frequently passage of an endoscope through the esophagus is impossible in these patients. Interventional, fluoroscopically assisted, percutaneous gastrostomy (PG) by balloon replacement tubes is a feasible and successful alternative to percutaneous endoscopic gastrostomy (PEG) and the method of choice in patients where the esophagus cannot be passed with an endoscope anymore. Technical success rate is very high and serious complications are rare. Radiological PG is a feasible, equivalent alternative to PEG also in all other patients. We recommend PG with balloon gastrostomy tubes in conjunction with gastropexy performed with three to four T-fasteners, which are left in place for seven days in order to prevent dislocation and leakage. (orig.)

  7. Fin-efficiency calculation for condensation in the presence of noncondensable gases

    Science.gov (United States)

    Panchal, C. B.

    Plate-fin heat exchangers are being considered for many condenser applications. They are commonly used for the gas-separation process because they can provide a high thermal performance to obtain a low mean-temperature difference, essential for the gas-separation process. Plate-fin heat exchangers are also considered for the heat-pump system using nonazeotropic refrigerant mixtures. The brazed plate-fin condenser was considered to be a leading candidate for the Ocean Thermal Energy Conversion (OTEC) system, where high-performance heat exchangers are essential for maintaining a low mean-temperature difference. Calculation of the fin efficiency is difficult for condensation in the presence of noncondensable gases due to the spatial variation of the interfacial temperature. An analysis was carried out to develop a simplified method to calculate the fin efficiency for condensation of a vapor in the presence of noncondensable gases. The analysis includes the variation in the interfacial temperature along the fin surface. Appropriate assumptions are made to simplify the coupled heat-conduction equation in the fin and the heat/mass fluxes at the interface. The resulting expression for the fin efficiency includes mass-flux parameters, and it is similar to the common expression used for single-phase flow.

  8. Satellite power system (SPS) magnetron tube assessment study

    Science.gov (United States)

    1980-01-01

    Taks performed to extend the data base and to define a technology development program for the magnetron directional amplifier for the SPS are reviewed. These include: (1) demonstrating the tracking of phase and amplitude of the microwave output to phase and amplitude references; (2) expanding the range of power over which the directional amplifier will operate; (3)recognizing the importance of amplitude control in overall system design and in simplifying power conditioning; (4) developing a preliminary design for the overall architecture of the power module; (5) demonstrating magnetron starting using the amplitude control system; (6) mathematically modelling and performing a computerized study of the pyrolytic graphite radiating fin; (7) defining the mass of the magnetic circuit for the SPS tube; (8) noise measurement; (9) achieving harmonic suppression by notch reflection filters; (10) estimating the mass of the transmitting antenna; (11) developing a magnetron package with power generation, phase control, and power condition functions; and (12) projecting magnetron package characteristics.

  9. Convective–radiative radial fins with convective base heating and convective–radiative tip cooling: Homogeneous and functionally graded materials

    International Nuclear Information System (INIS)

    Highlights: • Convective–radiative radial fins with base convective heating were analyzed. • Homogeneous material and functionally graded material fins were investigated. • Fin efficiency and the effects of dimensionless parameters in fins were analyzed. - Abstract: This paper studies a radial fin of uniform thickness with convective heating at the base and convective–radiative cooling at the tip. The fin is assumed to experience uniform internal heat generation. The exposed surfaces of the fin lose heat by simultaneous convection and radiation to the surroundings. Two types of fin materials are investigated: homogeneous material and functionally graded material (FGM). For the homogeneous material, the thermal conductivity is assumed to be a linear function of temperature, while for the FGM fin the thermal conductivity is modeled as a linear function of the dimensionless radial coordinate. The analysis is conducted using the differential transformation method (DTM). The accuracy of DTM is verified by comparing the results for the simplified versions of the present model with an exact analytical solution derived here. Once the accuracy of DTM is authenticated, the method is used to generate results for the general problem formulated here. These results illustrate the effects of various dimensionless parameters on the thermal performance of homogeneous material fins and FGM fins

  10. Prestaciones del Detector Central de Muones del Experimento CMS: las Camaras de Deriva y su Sistema de Trigger (Performance of the Central Muon Detector of the Experiment CMS: the Drift Tube Chambers and its Trigger System)

    CERN Document Server

    Muñoz, Carlos Villanueva

    2007-01-01

    Prestaciones del Detector Central de Muones del Experimento CMS: las Camaras de Deriva y su Sistema de Trigger (Performance of the Central Muon Detector of the Experiment CMS: the Drift Tube Chambers and its Trigger System)

  11. High temperature collecting performance of a new all-glass evacuated tubular solar air heater with U-shaped tube heat exchanger

    International Nuclear Information System (INIS)

    Highlights: • A novel solar air heater with simplified CPC and U-type heat exchanger is designed and tested. • The system is made up of 10 linked collecting panels. • Simplified CPC has a much lower cost at the expense of slight efficiency loss. • The air heater can propose the heated air exceeding 200 °C with great air flow rate. - Abstract: Experiment and simulation are conducted on a new-type all-glass evacuated tubular solar air heater with simplified compound parabolic concentrator (CPC). The system is made up of 10 linked collecting panels and each panel includes a simplified CPC and an all-glass evacuated tube with a U-shaped copper tube heat exchanger installed inside. Air is gradually heated when passing through each U-shaped copper tube. The heat transfer model of the solar air heater is established and the outlet air temperature, the heat power and heat efficiency are calculated. Calculated and experimental results show that the present experimental system can provide the heated air exceeding 200 °C. The whole system has an outstanding high-temperature collecting performance and the present heat transfer model can meet the general requirements of engineering calculations

  12. Influence of the receiver’s back surface radiative characteristics on the performance of a heat-pipe evacuated-tube solar collector

    International Nuclear Information System (INIS)

    Highlights: • A model for describing the heat transfer characteristics of the ETSC is derived. • A method by performing roughness treatment is proposed to change the emissivity. • Increasing the receiver’s back surface emissivity can greatly affect the heat loss. • Real weather test verifies the proposed method in controlling overheat phenomenon. - Abstract: The receiver’s back surface radiative characteristics of a heat-pipe evacuated-tube solar collector (ETSC) may have a significant influence on its performance. This influence is generally related to the back surface emissivity and temperature; however it has been not studied previously. This paper firstly presents a heat transfer model for the ETSC, which is then derived to characterize the relationship between the heat loss and the back surface emissivity of the ETSC. A steady state experiment has been also performed to measure the heat loss of ETSC with different back surface emissivity values. The experimental results indicate that the heat loss of the ETSC increases with the increase of the back surface emissivity, but the rate of increase differs for different operation temperatures. When the back surface emissivity increases from 0.03 to 0.12, the heat loss of ETSC only increases by 31% when the operation temperature is below 100 °C, but the heat loss will increase to 96% when the operation temperature is over 200 °C. This means that the change of back surface emissivity can significantly affect the performance of the ETSC at higher temperature but affect little at lower temperature. Based on this, a novel method by performing roughness treatment on the receiver’s back surface is proposed to solve the overheating problem of ETSC in summer. Two solar water heaters including 6 ETSCs with standard and roughness-treated tubes were tested under real weather condition. Experiment reveals that when the water temperature in tank is below 60 °C, the two solar water heaters own similar temperature change. But when the temperature is over 80 °C, the solar water heater with roughness-treated tube shows obviously lower temperature increase than that with standard tube. Therefore, it is very effective to prevent overheating of some solar water heaters used in high latitudes in summer by increasing the receiver’s back surface roughness

  13. Performance of a reciprocal shaker in mechanical dispersion of soil samples for particle-size analysis / Avaliação do desempenho de mesa agitadora reciprocante na dispersão de amostras de solo para fins de análise granulométrica

    Scientific Electronic Library Online (English)

    Thayse Aparecida, Dourado; Laura Fernanda Simões da, Silva; Mara de Andrade, Marinho.

    1131-11-01

    Full Text Available A dispersão da amostra de solo é uma etapa fundamental da análise granulométrica, sendo realizada mediante o uso de dispersantes químicos e agitação mecânica. O objetivo deste trabalho foi avaliar a eficiência de mesa agitadora reciprocante de baixa rotação na dispersão mecânica de amostras de solos [...] de diferentes classes texturais. Foram realizadas análises granulométricas em 61 amostras com quatro repetições, empregando o método da pipeta para determinação da fração argila e tamisagem para determinação das frações areia grossa, areia fina e areia total, sendo o silte determinado por diferença. Na avaliação de desempenho, os resultados obtidos com uso da mesa agitadora reciprocante (MAR) foram comparados com dados disponíveis para as mesmas amostras oriundos de relatórios do Ensaio de Proficiência IAC para Laboratórios de Análises de Solos - Prolab/IAC. Análises de acurácia foram realizadas com base nos valores dos intervalos de confiança definidos para cada fração granulométrica componente de cada amostra ensaiada. Indicadores gráficos também foram utilizados na comparação de dados, por meio de dispersão e ajuste linear. A estatística descritiva indicou preponderância de baixa variabilidade em mais de 90 % dos resultados obtidos para as amostras de texturas arenosa, média e argilosa e em 68 % dos obtidos para as amostras de textura muito argilosa, indicando boa repetibilidade dos resultados obtidos com a MAR. Média variabilidade foi mais frequentemente associada à fração silte, seguida da fração areia fina. Os resultados das análises de sensibilidade indicam acurácia de 100 % nas três frações granulométricas - areia total, silte e argila - para todas as amostras analisadas pertencentes às classes texturais muito argilosa, argilosa e média. Para as nove amostras de textura arenosa, a acurácia média foi de 85,2 %, e os maiores desvios ocorreram em relação à fração silte. Nas aproximações lineares, coeficientes de correlação igual (silte) ou superiores (areia total e argila) a 0,93, bem como diferenças menores do que 0,16 entre os coeficientes angulares das retas e o valor unitário, indicam alta correlação entre os resultados de referência (Prolab/IAC) e os obtidos nos ensaios com a MAR. Conclui-se pelo desempenho satisfatório da mesa agitadora reciprocante de baixa rotação para dispersão mecânica de amostras de solo de diferentes classes texturais para fins de análise granulométrica, permitindo recomendar o uso alternativo do equipamento quando se emprega agitação lenta. As vantagens do uso do equipamento nacional incluem o baixo custo, a possibilidade de análise simultânea de grande número de amostras e o uso de frascos comuns, de vidro ou de plástico, baratos e de fácil reposição. Abstract in english The dispersion of the samples in soil particle-size analysis is a fundamental step, which is commonly achieved with a combination of chemical agents and mechanical agitation. The purpose of this study was to evaluate the efficiency of a low-speed reciprocal shaker for the mechanical dispersion of so [...] il samples of different textural classes. The particle size of 61 soil samples was analyzed in four replications, using the pipette method to determine the clay fraction and sieving to determine coarse, fine and total sand fractions. The silt content was obtained by difference. To evaluate the performance, the results of the reciprocal shaker (RSh) were compared with data of the same soil samples available in reports of the Proficiency testing for Soil Analysis Laboratories of the Agronomic Institute of Campinas (Prolab/IAC). The accuracy was analyzed based on the maximum and minimum values defining the confidence intervals for the particle-size fractions of each soil sample. Graphical indicators were also used for data comparison, based on dispersion and linear adjustment. The descriptive statistics indicated predominantly low variability in more than 90 % of the results for sand, medium-textured and cla

  14. Mechanical Properties of Cold Gas Dynamic-Sprayed Near-Net-Shaped Fin Arrays

    Science.gov (United States)

    Cormier, Yannick; Dupuis, Philippe; Jodoin, Bertrand; Corbeil, Antoine

    2015-02-01

    This work focuses on the study of the adhesion and thermal performance of near-net-shaped pyramidal fin arrays manufactured by cold spray on aluminum alloy substrate coated with various bond coats: a cold-sprayed bond coat as well as nitrogen- and air-propelled arc-sprayed bond coats. Furthermore, the effects of the fin density, fin height, and substrate surface roughness on the adhesion strength of the fins deposited on Al6061 substrates were characterized. It was found that the fin density, the fin height, and the substrate roughness have little impact on the adhesion strength of this system. The adhesion strength was found to be inversely proportional to the surface hardness when investigating these parameters for the different thermal-spray bond coatings, with all the fin systems having a much greater strength than the theoretical application stresses. Finally, it was found that the increase in the fin's base layer's roughness increases the overall heat transfer, with the bond coat material having a negligible effect on the thermal resistance for this type of heat-exchanger configuration.

  15. Eddy current inspection of tubing

    International Nuclear Information System (INIS)

    The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)

  16. CFD-based Analysis of Aeroelastic behavior of Supersonic Fins

    OpenAIRE

    Tianxing Cai; Min Xu; Weigang Yao

    2011-01-01

    The main goal of this paper is to analyze the flutter boundary, transient loads of a supersonic fin, and the flutter with perturbation. Reduced order mode (ROM) based on Volterra Series is presented to calculate the flutter boundary, and CFD/CSD coupling is used to compute the transient aerodynamic load. The Volterra-based ROM is obtained using the derivative of unsteady aerodynamic step-response, and the infinite plate spline is used to perform interpolation of physical quantities between th...

  17. Design & modelling of a composite rudderless aeroelastic fin structure

    OpenAIRE

    Trapani, Matteo

    2010-01-01

    This thesis presents the study of a gapless and rudderless aeroelastic fin (GRAF) to enhance the directional stability and controllability of an aircraft. The GRAF concept was proposed and developed in the wake of previous research, targeted to improve flight performance and manoeuvrability, and to reduce fuel consumption and airframe weight. The study involved the subjects of aerodynamics, structural design and analysis, and flight mechanics. The work includes conceptual de...

  18. An experimental investigation into the deployment of 3-D, finned wing and shape memory alloy vortex generators in a forced air convection heat pipe fin stack

    International Nuclear Information System (INIS)

    Forced air convection heat pipe cooling systems play an essential role in the thermal management of electronic and power electronic devices such as microprocessors and IGBT's (Integrated Gate Bipolar Transistors). With increasing heat dissipation from these devices, novel methods of improving the thermal performance of fin stacks attached to the heat pipe condenser section are required. The current work investigates the use of a wing type surface protrusions in the form of 3-D delta wing tabs adhered to the fin surface, thin wings punched-out of the fin material and TiNi shape memory alloy delta wings which changed their angles of attack based on the fin surface temperature. The longitudinal vortices generated from the wing designs induce secondary mixing of the cooler free stream air entering the fin stack with the warmer fluid close to the fin surfaces. The change in angle of the attack of the active delta wings provide heat transfer enhancement while managing flow pressure losses across the fin stack. A heat transfer enhancement of 37% compared to a plain fin stack was obtained from the 3-D tabs in a staggered arrangement. The punched-out delta wings in the staggered and inline arrangements provided enhancements of 30% and 26% respectively. Enhancements from the active delta wings were lower at 16%. However, as these devices reduce the pressure drop through the fin stack by approximately 19% in the de-activate position, over the activated position, a reduction in fr the activated position, a reduction in fan operating cost may be achieved for systems operating with inlet air temperatures below the maximum inlet temperature specification for the device. CFD analysis was also carried out to provide additional detail of the local heat transfer enhancement effects. The CFD results corresponded well with previously published reports and were consistent with the experimental findings. - Highlights: ? Heat transfer enhancements of heat pipe fin stacks was successfully achieved using fixed and active delta wing vortex generators. ? The active vortex generators, made from Ti-Ni, protruded into the flow stream at high temperatures and resume a low profile position at a low temperature set point. ? By considering wing spacing and the distance from the leading edge of the fin stack, heat transfer enhancements of up to 37%, compared to plane fin stacks, were achieved. ? By replacing the fixed delta wings with the active vortex generators, heat transfer enhancements of up to 16% was achieved and the pressure loss associated with flow obstructions was effectively managed.

  19. Fin shape thermal optimization using Bejan's constuctal theory

    CERN Document Server

    Lorenzini, Giulio

    2011-01-01

    The book contains research results obtained by applying Bejan's Constructal Theory to the study and therefore the optimization of fins, focusing on T-shaped and Y-shaped ones. Heat transfer from finned surfaces is an example of combined heat transfer natural or forced convection on the external parts of the fin, and conducting along the fin. Fin's heat exchange is rather complex, because of variation of both temperature along the fin and convective heat transfer coefficient. Furthermore possible presence of more fins invested by the same fluid flow has to be considered.Classical fin theory tri

  20. Convection-radiation thermal analysis of triangular porous fins with temperature-dependent thermal conductivity by DTM

    International Nuclear Information System (INIS)

    Highlights: • Thermal analysis of a triangular porous fin is analytically studied. • The nonlinear energy equation is solved by means of DTM. • Temperature profile for different values of involved parameters is obtained and discussed. • Fin effectiveness and fin efficiency are calculated and discussed. • The fin temperature decreases by increasing Z, R? and Ra?, and reverse results were found for porosity. - Abstract: Increasing performance of porous fins is one of the common priorities nowadays. Hence attention here is given to the convection and radiation effects in the analysis of performance of a porous triangular fin with temperature-dependent thermal conductivity. Mathematical problem is solved by differential transformation method (DTM). The DTM results are compared with the numerical results obtained by fourth-order Runge–Kutta method in order to confirm the accuracy of the analytical solution. The dimensionless temperature distributions, fin efficiency and fin effectiveness are studied with respect to emerging parameters involved in the analysis. It is noted that there is an increase in fin performance in view of porous constraint

  1. First results of performance tests of the newly designed Vacuum Silicon Photo Multiplier Tube (VSiPMT)

    International Nuclear Information System (INIS)

    We invented (2007) the VSiPMT, a novel, high-gain, photo detector device and we publically proposed this idea in an International Conference for the first time at the 11th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD08) in Siena, triggering deep discussions on the feasibility of the device itself and on the convenience of such a solution. After several years spent in designing, evaluation, tests and eventually negotiations with some suppliers, we finally got a couple of prototypes of the Vacuum Silicon Photo Multiplier Tube (VSiPMT) made under our specifications by Hamamatsu. We present in this paper the most important results of characterization tests of the first prototypes of the VSiPMT

  2. Design, fabrication and performance of small, graphite electrode, multistage depressed collectors with 200-W, CW, 8- to 18-GHz traveling-wave tubes

    Science.gov (United States)

    Ebihara, Ben T.; Ramins, Peter

    1987-02-01

    Small multistage depressed collectors (MDC's) which used pyrolytic graphite, ion-beam-textured pyrolytic graphite, and isotropic graphite electrodes were designed, fabricated, and evaluated in conjuntion with 200-W, continuous wave (CW), 8- to 18-GHz traveling-wave tubes (TWT's). The design, construction, and performance of the MDC's are described. The bakeout performance of the collectors, in terms of gas evolution, was indistinguishable from that of typical production tubes with copper collectors. However, preliminary results indicate that some additional radiofrequency (RF) and dc beam processing time (and/or longer or higher temperature bakeouts) may be needed beyond that of typical copper electrode collectors. This is particularly true for pyrolytic graphite electrodes and for TWT's without appendage ion pumps. Extended testing indicated good long-term stability of the textured pyrolytic graphite and isotropic graphite electrode surfaces. The isotropic graphite in particular showed considerable promise as an MDC electrode material because of its high purity, low cost, simple construction, potential for very compact overall size, and relatively low secondary electron emission yield characteristics in the as-machined state. However, considerably more testing experience is required before definitive conclusions on its suitability for electronic countermeasure systems and space TWT's can be made.

  3. Steam generator tube integrity program

    Energy Technology Data Exchange (ETDEWEB)

    Dierks, D.R.; Shack, W.J. [Argonne National Laboratory, IL (United States); Muscara, J.

    1996-03-01

    A new research program on steam generator tubing degradation is being sponsored by the U.S. Nuclear Regulatory Commission (NRC) at Argonne National Laboratory. This program is intended to support a performance-based steam generator tube integrity rule. Critical areas addressed by the program include evaluation of the processes used for the in-service inspection of steam generator tubes and recommendations for improving the reliability and accuracy of inspections; validation and improvement of correlations for evaluating integrity and leakage of degraded steam generator tubes, and validation and improvement of correlations and models for predicting degradation in steam generator tubes as aging occurs. The studies will focus on mill-annealed Alloy 600 tubing, however, tests will also be performed on replacement materials such as thermally-treated Alloy 600 or 690. An overview of the technical work planned for the program is given.

  4. Reliability of steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Kadokami, E. [Mitsubishi Heavy Industries Ltd., Hyogo-ku (Japan)

    1997-02-01

    The author presents results on studies made of the reliability of steam generator (SG) tubing. The basis for this work is that in Japan the issue of defects in SG tubing is addressed by the approach that any detected defect should be repaired, either by plugging the tube or sleeving it. However, this leaves open the issue that there is a detection limit in practice, and what is the effect of nondetectable cracks on the performance of tubing. These studies were commissioned to look at the safety issues involved in degraded SG tubing. The program has looked at a number of different issues. First was an assessment of the penetration and opening behavior of tube flaws due to internal pressure in the tubing. They have studied: penetration behavior of the tube flaws; primary water leakage from through-wall flaws; opening behavior of through-wall flaws. In addition they have looked at the question of the reliability of tubing with flaws during normal plant operation. Also there have been studies done on the consequences of tube rupture accidents on the integrity of neighboring tubes.

  5. Steam generator tube extraction

    International Nuclear Information System (INIS)

    To enable tube examination on steam generators in service, Framatome has now developed a process for removing sections of steam generator tubes. Tube sections can be removed without being damaged for treating the tube section expanded in the tube sheet

  6. Study on antioxidant experiment on forged steel tube sheet and tube hole for steam generator

    International Nuclear Information System (INIS)

    Antioxidant experiment on forged steel tube sheet and tube hole for steam generator was studied and the influence of different simulated heat treatments on the antioxidant performance of tube sheet and tube hole was made. The influence of different antioxidant methods on the size of tube hole was drawn. Furthermore, the change of size and weight of 18MnD5 forged steel tube sheet on the condition of different simulated heat treatments was also studied. The analytical results have proved reference information for the use of 18MnD5 material and for key processes of processing tube hole and wearing and expanding U-style tube. (authors)

  7. Proteomic Analysis of Zebrafish Caudal Fin Regeneration*

    OpenAIRE

    Saxena, Sandeep; Singh, Sachin K.; Lakshmi, Mula G. Meena; Meghah, Vuppalapaty; Bhatti, Bhawna; Swamy, Cherukuvada V. Brahmendra; Sundaram, Curam S.; Idris, Mohammed M.

    2012-01-01

    The epimorphic regeneration of zebrafish caudal fin is rapid and complete. We have analyzed the biomechanism of zebrafish caudal fin regeneration at various time points based on differential proteomics approaches. The spectrum of proteome changes caused by regeneration were analyzed among controls (0 h) and 1, 12, 24, 48, and 72 h postamputation involving quantitative differential proteomics analysis based on two-dimensional gel electrophoresis matrix-assisted laser desorption/ionization and ...

  8. The art of fin regeneration in zebrafish

    OpenAIRE

    Pfefferli, Catherine; Ja?wi?ska, Anna

    2015-01-01

    The zebrafish fin provides a valuable model to study the epimorphic type of regeneration, by which the amputated part of the appendage is nearly perfectly replaced. To accomplish fin regeneration, two reciprocally interacting domains need to be established at the injury site, namely, a wound epithelium and a blastema. The wound epithelium provides a supporting niche for the blastema, which contains mesenchyme-derived progenitor cells for the regenerate. The fate of blastemal daughter cells de...

  9. FLOW DISTRIBUTION IN A SOLAR COLLECTOR PANEL WITH HORIZONTAL FINS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan

    2005-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontal fins. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics (CFD) calculations. Further, experimental investigations of a 12.5 m² solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured temperatures are compared to the temperatures determined by the CFD model and there is a good similarity between the measured and calculated results. Calculations with the CFD model elucidate the flow and temperature distribution in the collector. The influences of operating conditions such as flow rate, temperature of inlet flow and collector tilt angle are shown. Based on the investigations preliminary recommendations for theoperation of the investigated collector are given. For instance, minimum flow rate in order to avoid boiling in the horizontal strips is recommended.

  10. Necropsy report of a fin whale (Balaenoptera physalus) stranded in Denmark in 2010

    DEFF Research Database (Denmark)

    Alstrup, Aage K. O.; Hedayat, Abdi

    2013-01-01

    There is little detailed information on stranded fin whales (Balaenoptera physalus) in the scientific literature (Notarbartolo di Sciara et al., 2003). In Denmark, at least eight fin whales stranded between the years 1603 and 1958 (Kinze, 1995). On 16 June 2010, a live subadult or adult male fin whale stranded in the Bay of Vejle (55º 69' N, 9º 58' E), Denmark. Despite several attempts, it was not possible to rescue the fin whale, which was only partially exposed by the water. The fin whale succumbed after 5 d stranded in shallow water. The dead fin whale was transported to a nearby pier, and a necropsy was performed by a multidisciplinary team, including biologists, conservationists, physicians, and veterinarians representing three universities and several museums.

  11. Coiled tubing

    International Nuclear Information System (INIS)

    Oil and gas wells that flow on initial completion eventually reach a condition of liquid loading that kills the wells. This results form declining reservoir pressure, decreased gas volume (velocity), increased water production and other factors that cause liquids to accumulate at the bottom of the well and exert back pressure on the formation. This restricts or in some cases prevents fluid entry into the wellbore form the formation. Flowing production can be restored or increased by reducing surface backpressure, well bore stimulation, pressure maintenance or by installing a string of smaller diameter tubing. This paper reports on installation (hanging off) of a concentric string of coiled tubing inside existing production tubing which is an economically viable, safe, convenient and effective alterative for returning some of these liquid loaded )logged-up) wells to flowing status

  12. Three-dimensional structural analysis of the plate-fin heat exchanger

    International Nuclear Information System (INIS)

    The Brazed aluminum plate-fin heat exchanger is a complex structure consisting of a core, headers and nozzles. The core is built of many layers of flat parting sheets and corrugated fins, and is sealed by side bars. Stress patterns in this type of heat exchanger have so far not been accurately analyzed, due to the complexity of the structure. A three dimensional structural analysis of such a core-header-nozzle structure subject to internal pressure is performed herein, using the finite element method, in order to investigate the mechanical characteristics of the structure. In the analysis, the corrugated fin is modeled by an equivalent anisotropic continuum element, to save on the computational cost. The adequacy of the analysis is then verified by performing a strain measurement test on the actual plate-fin heat exchanger. On the basis of the analytical results, it becomes clear that some critical parts need special attention when designing such structures

  13. Análise de fármacos em material biológico: acoplamento microextração em fase sólida "no tubo" e cromatografia líquida de alta eficiência Analysis of drugs in biological samples: automated "in-tube" solid-phase microextraction and high performance liquid chromatography

    OpenAIRE

    Queiroz, Maria Euge?nia C.; Lanc?as, Fernando M.

    2005-01-01

    A new solid phase microextraction (SPME) system, known as in-tube SPME, was recently developed using an open tubular fused-silica capilary column, instead of an SPME fiber, as the SPME device. On-line in-tube SPME is usually used in combination with high performance liquid chromatography. Drugs in biological samples are directly extracted and concentrated in the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and then directly transferred to the liquid ...

  14. Thermal management of electronics using phase change material based pin fin heat sinks

    International Nuclear Information System (INIS)

    This paper reports the results of an experimental study carried out to explore the thermal characteristics of phase change material based heat sinks for electronic equipment cooling. The phase change material (PCM) used in this study is n – eicosane. All heat sinks used in the present study are made of aluminium with dimensions of 80 × 62 mm2 base with a height of 25 mm. Pin fins acts as the thermal conductivity enhancer (TCE) to improve the distribution of heat more uniformly as the thermal conductivity of the PCM is very low. A total of three different pin fin heat sink geometries with 33, 72 and 120 pin fins filled with phase change materials giving rise to 4%, 9% and 15% volume fractions of the TCE respectively were experimentally investigated. Baseline comparisons are done with a heat sink filled with PCM, without any fin. Studies are conducted for heat sinks on which a uniform heat load is applied at the bottom for the finned and unfinned cases. The effect of pin fins of different volume fractions with power levels ranging from 4 to 8 W corresponding to a heat flux range of 1. 59 to 3.17 kW/m2, was explored in this paper. The volume fraction of the PCM (PCM volume / (Total volume – fin volume)) is also varied as 0. 3, 0.6 and 1 to determine the effect of PCM volume on the overall performance of the electronic equipment.

  15. Exergy analysis and performance of a counter flow Ranque-Hilsch vortex tube having various nozzle numbers at different inlet pressures of oxygen and air

    Energy Technology Data Exchange (ETDEWEB)

    Kirmaci, Volkan [Bartin University, Faculty of Engineering, Mechanical Engineering Department, 74100 Bartin (Turkey)

    2009-11-15

    An experimental investigation is made to determine the effects of the orifice nozzle number and the inlet pressure on the heating and cooling performance of the counter flow Ranque-Hilsch vortex tube when air and oxygen used as a fluid. The orifices used at these experiments are made of the polyamide plastic material. The thermal conductivity of polyamide plastic material is 0.25 W/m C. Five orifices with nozzle numbers of 2, 3, 4, 5 and 6 have been manufactured and used during the experiments. For each one of the orifices (nozzle numbers) when used with two different fluids, inlet pressures were adjusted from 150 kPa to 700 kPa with 50 kPa increments, and the exergy efficiency was determined. During the experiments, a vortex tube is used with an L/D ratio of 15, and cold mass fraction is held constant at 0.5. As a result of the experimental study, it is determined that the temperature gradient between the hot and cold fluid is decreased with increasing of the orifice nozzle number. (author)

  16. Template-assisted formation of microsized nanocrystalline CeO2 tubes and their catalytic performance in the carboxylation of methanol

    Directory of Open Access Journals (Sweden)

    Jörg J. Schneider

    2011-11-01

    Full Text Available Polymethylmethacrylate (PMMA/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO2 tubes, with a diameter of ca. 0.75 µm, composed of nanocrystalline agglomerated ceria particles were thus obtained. The 1-D ceramic ceria material was characterized by X-ray diffraction, scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HRTEM, UV–vis and photoluminescence spectroscopy (PL, as well as thermogravimetric analysis (TGA. Its catalytic performance was studied in the direct carboxylation of methanol with carbon dioxide leading to dimethyl carbonate [(CH3O2CO, DMC], which is widely employed as a phosgene and dimethyl sulfate substitute, and as well as a fuel additive.

  17. ATLAS monitored drift tube long-term stability and aging study performed for the first time with the gas-recirculation system planned for LHC

    CERN Document Server

    Zimmermann, S

    2004-01-01

    The monitored drift tubes (MDTs) of the ATLAS muon spectrometer have to sustain count rates up to 1500 Hz/cm and must be able to survive an accumulated charge of up to 0.6 C/cm during 10 years of operation. This paper presents results of aging studies carried out at the CERN Gamma Irradiation Facility GIF for the first time with a final ATLAS muon chamber and a prototype of the gas recirculation system planned at LHC. A loss in pulse height was observed for MDTs under gas recirculation after an accumulated charge equivalent to only 1 year of LHC operation; the effect was traced to a silicone contamination from bad components in the gas recirculation system. Tubes operated with the classical one-pass, flushing mode did not show any evidence of aging, thus (re)validating the materials and components used in the MDT construction. Questions of long-term stability when recycling the major part of the operating gas could also be addressed by the measurements performed; results on this will also be discussed. (6 ref...

  18. Embedded SMA wire actuated biomimetic fin: a module for biomimetic underwater propulsion

    International Nuclear Information System (INIS)

    An embedded shape memory alloy (SMA) wire actuated biomimetic fin is presented, and based on this module for biomimetic underwater propulsion, a micro robot fish (146 mm in length, 30 g in weight) and a robot squid (242 mm in length, 360 g in weight) were developed. Fish swim by undulating their body and/or fins. Squid and cuttlefish can also swim by undulating their fins. To simplify engineering modeling, the undulating swimming movement is assumed to be the integration of the movements of many flexible bending segments connected in parallel or in series. According to this idea, a biomimetic fin which can bend flexibly was developed. The musculature of a cuttlefish fin was investigated to aid the design of the biomimetic fin. SMA wires act as 'muscle fibers' to drive the biomimetic fin just like the transverse muscles of the cuttlefish fin. During the bending phase, elastic energy is stored in the elastic substrate and skin, and during the return phase, elastic energy is released to power the return movement. Theorem analysis of the bending angle was performed to estimate the bending performance of the biomimetic fin. Experiments were carried out on single-face fins with latex rubber skin and silicone skin (SF-L and SF-S) to compare the bending angle, return time, elastic energy storage and reliability. Silicone was found to be the better skin. A dual-face fin with silicone skin (DF-S) was tested in water to evaluate the actuating performance and to validate the reliating performance and to validate the reliability. Thermal analysis of the SMA temperature was performed to aid the control strategy. The micro robot fish and robot squid employ one and ten DF-S, respectively. Swimming experiments with different actuation frequencies were carried out. The speed and steering radius of the micro robot fish reached 112 mm s?1 and 136 mm, respectively, and the speed and rotary speed of the robot squid reached 40 mm s?1 and 22° s?1, respectively

  19. Performance evaluation criteria for use of enhanced heat transfer surfaces in heat exchanger design

    International Nuclear Information System (INIS)

    Previous work of Bergles and Webb is extended to establish a broad range of Performance Evaluation Criteria (PEC) applicable to single phase flow in tubes. The equations include the effects of shell-side enhancement and fouling and are applicable to roughness and internally finned tubes. Detailed procedures are outlined to calculate the performance improvement and to select the 'optimum' surface geometry. PEC are presented for four design cases: (1) reduced heat exchanger material; (2) increased heat duty- (3) reduced log-mean temperature difference- and (4) reduced pumping power. The 11 cases discussed include fixed flow area and variable flow area. Appropriate PEC for two-phase exchangers are also discussed. (author)

  20. Comparison of observer performance on soft-copy reading of digital chest radiographs: High resolution liquid-crystal display monitors versus cathode-ray tube monitors

    International Nuclear Information System (INIS)

    The purpose of this study is to compare observer performance for detection of abnormalities on chest radiographs with 5-megapixel resolution liquid-crystal displays (LCD) and 5-megapixel resolution cathode-ray tube (CRT) monitors under bright and subdued ambient light conditions. Six radiologists reviewed a total of 254 digital chest radiographs under four different conditions with a combination of two types of monitors (a 5-megapixel resolution LCD and a 5-megapixel resolution CRT monitor) and with two types of ambient light (460 and 50 lux). The abnormalities analyzed were nodules, pneumothorax and interstitial lung disease. For each reader, the detection performance using 5-megapixel LCD and 5-megapixel CRT monitors under bright and subdued ambient light conditions were compared using multi-case and multi-modality ROC analysis. For each type of ambient light, the average detection performance with the two types of monitors was also compared. For each reader, the observer performance of 5-megapixel LCD and 5-megapixel CRT monitors, under both bright and subdued ambient light conditions, showed no significant statistical differences for detecting nodules, pneumothorax and interstitial lung disease. In addition, there was no significant statistical difference in the average performance when the two monitor displays, under both bright and subdued ambient light conditions, were compared

  1. Methylmercury in dried shark fins and shark fin soup from American restaurants.

    Science.gov (United States)

    Nalluri, Deepthi; Baumann, Zofia; Abercrombie, Debra L; Chapman, Demian D; Hammerschmidt, Chad R; Fisher, Nicholas S

    2014-10-15

    Consumption of meat from large predatory sharks exposes human consumers to high levels of toxic monomethylmercury (MMHg). There also have been claims that shark fins, and hence the Asian delicacy shark fin soup, contain harmful levels of neurotoxic chemicals in combination with MMHg, although concentrations of MMHg in shark fins are unknown. We measured MMHg in dried, unprocessed fins (n=50) of 13 shark species that occur in the international trade of dried shark fins as well as 50 samples of shark fin soup prepared by restaurants from around the United States. Concentrations of MMHg in fins ranged from 9 to 1720 ng/g dry wt. MMHg in shark fin soup ranged from <0.01 to 34 ng/mL, with MMHg averaging 62 ± 7% of total Hg. The highest concentrations of MMHg and total Hg were observed in both fins and soup from large, high trophic level sharks such as hammerheads (Sphyrna spp.). Consumption of a 240 mL bowl of shark fin soup containing the average concentration of MMHg (4.6 ng/mL) would result in a dose of 1.1 ?g MMHg, which is 16% of the U.S. EPA's reference dose (0.1 ?g MMHg per 1 kg per day in adults) of 7.4 ?g per day for a 74 kg person. If consumed, the soup containing the highest measured MMHg concentration would exceed the reference dose by 17%. While shark fin soup represents a potentially important source of MMHg to human consumers, other seafood products, particularly the flesh of apex marine predators, contain much higher MMHg concentrations and can result in substantially greater exposures of this contaminant for people. PMID:24835340

  2. Tube Zither

    Science.gov (United States)

    Oakland Discovery Centers

    2012-01-01

    In this activity, learners explore sound by constructing tube zithers, stringed instruments from Southeast Asia and the South Pacific. Use this activity to demonstrate principles of sound including vibration, pitch, tone, frequency, and volume. Note: this activity requires the use of a drill, not included in the cost of materials.

  3. Mystery Tubes

    Science.gov (United States)

    University of California Museum of Paleontology

    2010-01-01

    Learners investigate a pre-constructed mystery tube to determine its interior mechanism. Working in small groups, learners pose explanations (hypotheses) for what they are observing and test their hypotheses. In a possible extension of this activity, learners build their own model to test their hypothesis. This lesson serves as a good introduction to the nature of scientific inquiry.

  4. Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

    OpenAIRE

    Aabye Martine G; Hermansen Thomas Stig; Ruhwald Morten; PrayGod George; Faurholt-Jepsen Daniel; Jeremiah Kidola; Faurholt-Jepsen Maria; Range Nyagosya; Friis Henrik; Changalucha John; Andersen Aase B; Ravn Pernille

    2012-01-01

    Abstract Background False negative and indeterminate Interferon Gamma Release Assay (IGRA) results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB) and to impair Interferon-gamma (IFN-?) responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively. Methods Patient...

  5. Whole shaft visibility and mechanical performance for active MR catheters using copper-nitinol braided polymer tubes

    OpenAIRE

    McVeigh Elliot R; Ozturk Cengizhan; Ratnayaka Kanishka; Faranesh Anthony Z; Guttman Michael A; Saikus Christina E; Kocaturk Ozgur; Lederman Robert J

    2009-01-01

    Abstract Background Catheter visualization and tracking remains a challenge in interventional MR. Active guidewires can be made conspicuous in "profile" along their whole shaft exploiting metallic core wire and hypotube components that are intrinsic to their mechanical performance. Polymer-based catheters, on the other hand, offer no conductive medium to carry radio frequency waves. We developed a new "active" catheter design for interventional MR with mechanical performance resembling braide...

  6. Coupling of a modified in-tube solid phase microextraction technique with high performance liquid chromatography-fluorescence detection for the ultra-trace determination of polycyclic aromatic hydrocarbons in water samples

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, H.; Salemi, A. [Sharif Univ. of Technology, Teheran (Iran). Dept. of Chemistry

    2004-04-01

    A modified in-tube solid phase microextraction (SPME) technique in conjunction with a high performance liquid chromatography (HPLC) was developed for the trace determination of polycyclic aromatic hydrocarbons (PAHs) in water samples. The extraction device contained a regular HPLC syringe, replacing the metallic needle by two concentric fused silica capillary tubes. The capillary tubes were coated with polydimethylsiloxane (PDMS) as the sorbent and were attached to the syringe by a homemade interface made from polyether ether ketone (PEEK). The sorption of analytes was achieved by frequent withdrawing and ejecting the water sample from/into a vial via the capillary tubes. For the desorption step, an aliquot of organic solvent was withdrawn and subsequently injected directly into the HPLC system. Limits of detection for the elected PAHs were between 0.001 and 0.006 {mu}g L{sup -1} with a RSD of 2.6-6.3%. (orig.)

  7. Análise de fármacos em material biológico: acoplamento microextração em fase sólida "no tubo" e cromatografia líquida de alta eficiência / Analysis of drugs in biological samples: automated "in-tube" solid-phase microextraction and high performance liquid chromatography

    Scientific Electronic Library Online (English)

    Maria Eugênia C., Queiroz; Fernando M., Lanças.

    2005-10-01

    Full Text Available [...] Abstract in english A new solid phase microextraction (SPME) system, known as in-tube SPME, was recently developed using an open tubular fused-silica capilary column, instead of an SPME fiber, as the SPME device. On-line in-tube SPME is usually used in combination with high performance liquid chromatography. Drugs in b [...] iological samples are directly extracted and concentrated in the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and then directly transferred to the liquid chromatographic column. In-tube SPME is suitable for automation. Automated sample handling procedures not only shorten the total analysis time, but also usually provide better accuracy and precision relative to manual techniques. In-tube SPME has been demonstrated to be a very effective and highly sensitive technique to determine drugs in biological samples for various purposes such as therapeutic drug monitoring, clinical toxicology, bioavailability and pharmacokinetics.

  8. Análise de fármacos em material biológico: acoplamento microextração em fase sólida "no tubo" e cromatografia líquida de alta eficiência Analysis of drugs in biological samples: automated "in-tube" solid-phase microextraction and high performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    Maria Eugênia C. Queiroz

    2005-10-01

    Full Text Available A new solid phase microextraction (SPME system, known as in-tube SPME, was recently developed using an open tubular fused-silica capilary column, instead of an SPME fiber, as the SPME device. On-line in-tube SPME is usually used in combination with high performance liquid chromatography. Drugs in biological samples are directly extracted and concentrated in the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and then directly transferred to the liquid chromatographic column. In-tube SPME is suitable for automation. Automated sample handling procedures not only shorten the total analysis time, but also usually provide better accuracy and precision relative to manual techniques. In-tube SPME has been demonstrated to be a very effective and highly sensitive technique to determine drugs in biological samples for various purposes such as therapeutic drug monitoring, clinical toxicology, bioavailability and pharmacokinetics.

  9. Analysis of estrogens in environmental waters using polymer monolith in-polyether ether ketone tube solid-phase microextraction combined with high-performance liquid chromatography.

    Science.gov (United States)

    Wen, Yi; Zhou, Bing-Sheng; Xu, Ying; Jin, Shi-Wei; Feng, Yu-Qi

    2006-11-10

    A simple, rapid and sensitive on-line method for simultaneous determination of four endocrine disruptors (17beta-estradiol, estriol, bisphenol A and 17alpha-ethinylestradiol) in environmental waters was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). A poly(acrylamide-vinylpyridine-N,N'-methylene bisacrylamide) monolith, synthesized inside a polyether ether ketone (PEEK) tube, was selected as the extraction medium. To achieve optimum extraction performance, several parameters were investigated, including extraction flow-rate, extraction time, and pH value, inorganic salt and organic solvent content of the sample matrix. By simply filtered with nylon membrane filter and adjusting the pH of samples to 6.0 with phosphoric acid, the sample solution then could be directly injected into the device for extraction. Low detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method were achieved in the range of 0.006-0.10 ng/mL and 0.02-0.35 ng/mL from spiked lake waters, respectively. The calibration curves of four endocrine disruptors showed good linearity ranging from quantification limits to 50 ng/mL with a linear coefficient R(2) value above 0.9913. Good method reproducibility was also found by intra- and inter-day precisions, yielding the RSDs less than 12 and 9.8%, respectively. Finally, the proposed method was successfully applied to the determination of these compounds in several environmental waters. PMID:16945381

  10. Optimum design of a radial heat sink with a fin-height profile for high-power LED lighting applications

    International Nuclear Information System (INIS)

    Highlights: • A radial heat sink was designed for high-power LED lighting applications. • Fin-height profiles reflecting the chimney-flow characteristics of a radial heat sink were proposed. • Multi-disciplinary optimization was carried out to simultaneously minimize the thermal resistance and mass. • The cooling performance of the optimized design showed improvement without additional mass increment. - Abstract: Light-emitting diode (LED) lighting offers greater energy efficiency than conventional lighting. However, if the heat from the LEDs is not properly dissipated, the lifespan and luminous efficiency are diminished. In the present study, a heat sink of LED lighting was optimized with respect to its fin-height profile to obtain reliable cooling performance for high-power LED lighting applications. Natural convection and radiation heat transfer were taken into consideration and an experiment was conducted to validate the numerical model. Fin-height profiles reflecting a three-dimensional chimney-flow pattern were proposed. The outermost fin height, the difference between fin heights, and the number of fin arrays were adopted as design variables via sensitivity analysis, and the heat sink configuration was optimized in three dimensions. Optimization was conducted to simultaneously minimize the thermal resistance and mass. The result was compared with the Pareto fronts of a plate-fin heat sink examined in a previous study. The cooling performance of the optimized design showed an improvement of more than 45% while preserving a mass similar to that of the plate-fin heat sink

  11. Performance evaluation of reverse osmosis with disc tube module for treatment of low level radioactive liquid waste

    International Nuclear Information System (INIS)

    Technological advances in the field of Reverse Osmosis (RO) and its use in the desalination and purification of seawater, brackish water and potable water has been extended towards management of radioactive liquid waste. Feasibility of RO based membrane process for treatment of radioactive Low Level Liquid Waste (LLW) has been explored using laboratory scale experimental set up. Based on the encouraging results obtained during laboratory scale studies, a pilot scale facility of capacity 30 m3/d with disc tube modules of polyamide based RO membrane have been installed, commissioned at Effluent Treatment Plant (ETP) and operated using actual LLW effluent to generate the engineering scale data and optimize various process parameters. It has been observed that when a feed of ? 10 Bq/ml of activity and less than 1000 ppm of total dissolved solids was processed, permeate activity reported was less than 1 Bq/ml (volume was 80-90%) can be discharged directly to sea. Activity was concentrated in about 10-20% of the initial volume, which could be treated efficiently by chemical treatment. Problem pertaining to biofouling of the membrane due to algae growth was solved by the use of sodium hypochlorite in the feed tank. Optimized concentration (5 ppm) of hypochlorite was added in the feed tank and excess free chlorine was destroyed by dosing of appropriate amount of sodium metabi-sulphite. Efforts were extended for continuous operation of DT-RO demonstration facility to establish the usefulness of RO as one of the suitable techniques for management of LLW. Various combinations of standard cleaning agents were tried for de-clogging of RO modules. During the demonstration trials, about 800 m3 of LLW was treated safely and successfully by RO thereby reducing the discharges through aquatic route. The reject of RO, which is a concentrated stream, was further treated chemically, thus reducing the solid waste generation. The data generated during study is presented. Experience gained during this study is planned to be utilized for conceptualizing of large capacity RO plant as a part of futuristic waste management scheme at ETP, Trombay. (author)

  12. A comparison of the effect of the electrohydrodynamic technique on the condensation heat transfer of HFC-134a inside smooth and micro-fm tubes

    International Nuclear Information System (INIS)

    The results of the condensation heat transfer enhancement and pressure drop of HFC-134a by using the electrohydrodynamic (EHD) technique are presented. The test section is a horizontal tube-in-tube heat exchanger where the refrigerant flows in the inner tube and water flows in the annulus. The outer tube is a smooth copper tube having outer diameter of 21.2 mm. Two types of inner tubes, smooth and micro-fin copper tubes, are tested. The outer diameter and length of both inner tubes is 9.52 mm and 2.5 m, respectively. A stainless steel cylindrical electrode of 1.47 mm in diameter is placed in the center of the tube. Experiments are conducted under conditions providing mass flux of 400 kg/m2s, saturated temperature of 40 .deg. C, heat flux of 20 kW/m2 and applied voltage of 2.5 kV. The experimental results indicate that the EHD enhancements of the smooth tube are higher than those of the micro-fin tube over the range of average quality. The maximum heat transfer enhancements for smooth and micro-fin tubes are 1.1. times and 1.08 times, respectively. For a smooth tube, the pressure drop induced by EHD is considerably small. However, the application of EHD in a micro-fin tube can lead to 10% increase in the pressure drop

  13. The use of hand paddles and fins in front crawl: biomechanical and physiological responses

    Directory of Open Access Journals (Sweden)

    Cristiano Cardoso de Matos

    2013-04-01

    Full Text Available Paddles and fins are used during swim training and practice as tools for improving performance. The use of these equipment can alter physiological and kinematic parameters of swimming. The purpose of this literature review was to present and discussthe effects of paddles and fins on kinematic and physiological variables in front crawl,and provide update on the topic for teachers, researchers, coaches and swimmers. Thirty articles were reviewed. To crawl, paddles can change the averages of stroke length and stroke rate, the average swimming speed, the absolute duration of the stroke phases and the index of coordination. Fins can modify the average stroke rate, the average swimming speed, the kick frequency and deep, and the energy cost. We found no studies that verified the longitudinal effects of the use of paddles and fins on these parameters.

  14. Electron tube

    Science.gov (United States)

    Suyama, Motohiro (Hamamatsu, JP); Fukasawa, Atsuhito (Hamamatsu, JP); Arisaka, Katsushi (Los Angeles, CA); Wang, Hanguo (North Hills, CA)

    2011-12-20

    An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

  15. Neutron tubes

    Science.gov (United States)

    Leung, Ka-Ngo (Hercules, CA); Lou, Tak Pui (Berkeley, CA); Reijonen, Jani (Oakland, CA)

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  16. A numerical study of entry region laminar mixed convection over shrouded vertical fin arrays

    International Nuclear Information System (INIS)

    A computational study of laminar mixed convection over a shrouded vertical rectangular fin array attached to a vertical base has been performed. Maintaining the base-fin system above the surrounding temperature, a fan velocity is imposed to enhance the heat transfer through the mixed convection process. Present study finds the effects of clearance spacing, fin spacing, fin length, Reynolds number and Grashof number on the thermal performance of the base-fin system. Mixed convection inlet velocity is decoupled to forced and natural convection velocity components and the resulting pressure drop across the duct length arises purely due to the forced convection velocity component. Thus, Reynolds number is estimated based on forced convection velocity component as the inlet velocity does not vanish even in pure natural convection. Computed local Nusselt number shows sharp drop near the entrance and reaches a fully developed value after a certain stream-wise distance from the entrance. Further, fully developed local Nusselt number shows a clear maximum at the clearance spacing of 0.075 and 0.15 for the inter-fin spacing of 0.3 and 0.5 respectively. Pressure drop across the duct, induced natural convection velocity and overall Nusselt number are well correlated with the governing parameters of the problem. (authors)

  17. Influence of Pr on Natural Convection Heat Transfer of an Open Channel Finned Plate

    International Nuclear Information System (INIS)

    The finned plate provides the extended heat transfer area and improves the heat transfer. However when the fin spacing becomes small, the pressure drop increases due to frictional loss, heat transfer is impaired. Thus there is an optimal fin spacing. For the natural convection heat transfer, the heated thermal boundary layer drives the flow and the influence of the Prandtl number on the heat transfer will be very important as the thickness of the thermal boundary layer depends on it. This study aims at investigating the influence of the Prandtl number on the natural convection heat transfer of the finned plate. Numerical analyses were performed by varying the Pr from 2 to 2,014. Numerical analysis was performed for the natural convection heat transfer of a finned plate in an open channel. In order to investigate the influence of the Prandtl number on the heat transfer, four different values of Prandtl numbers were simulated and compared. As expected, the velocity profiles were almost similar except for the fact that the boundary layer develops earlier for smaller Prandtl number fluid. However the temperature profiles varied drastically depending on the values of the Prandtl number. As the Prandtl number increases, the thermal boundary layer reduces. The comparisons of the results with Le Fevre natural convection heat transfer correlation for vertical plate shows that as the Pr increases, the NuL of the finned plate becomes similar to that of the flat plate of the same heat transfer area

  18. Performance improvement of small gamma camera using NaI(Tl) plate and position sensitive photo-multiplier tubes

    International Nuclear Information System (INIS)

    The purpose of this study was to improve the performance of a small gamma camera, utilizing a NaI(Tl) plate and a 5'' position sensitive PMT. We attempted to build a NaI(Tl) plate crystal system which retained all its advantages, while at the same time integrating some of the advantages inherent in an array-type scintillation crystal system. Flood images were obtained with a lead hole mask, and position mapping was performed by detecting hole positions in the flood image. Energy calibration was performed using the energy spectra obtained from each hole position. Flood correction was performed using a uniformity correction table containing the relative efficiency of each image element. The spatial resolution was improved about 16% after correction at the centre field of view. Resolution deterioration at the outer field of view (OFOV) was considerably ameliorated, from 6.7 mm to 3.2 mm after correction. The sensitivity at the OFOV was also increased after correction, from 0.7 cps ?Ci-1 to 2.0 cps ?Ci-1. The correction also improved uniformity, from 5.2% to 2.1%, and linearity, from 0.5 mm to 0 mm. The results of this study indicate that the revised correction method can be employed to considerably improve the performance of a small gamma camera using a NaI(Tl) plate-type crystal. This method also provides high spatial resolution and linearity, like array-type crystals do, while retaining the specific advantages of plate-type crystalsages of plate-type crystals

  19. Superconducting niobium cavity with cooling fins

    International Nuclear Information System (INIS)

    Cooling efficiency of a superconducting cavity is shown to be improved by applying a fin structure. Internal heating can be suppressed in a certain degree and the higher rf field is expected to be reached on surfaces of the cavity which is immersed in superfluid He4 liquid. The rf measurements were made on a C-band niobium cavity with cylindrical and circular fins around the wall. Fields of 39 mT and 25 MV/m were attained for TM010 mode cavity after surface treatments including high temperature annealing in a UHV furnace. (auth.)

  20. Thermoelectric generator with hinged assembly for fins

    International Nuclear Information System (INIS)

    A cylindrical casing has a central shielded capsule of radioisotope fuel. A plurality of thermonuclear modules are axially arranged with their hot junctions resiliently pressed toward the shield and with their cold junctions adjacent a transition member having fins radiating heat to the environment. For each module, the assembly of transition member and fins is hinged to the casing for swinging to permit access to and removal of such module. A ceramic plate having gold layers on opposite faces prevents diffusion bonding of the hot junction to the shield

  1. The comparison of corrosion resistance between Baosteel's alloy 690 tube and foreign alloy 690 tube

    International Nuclear Information System (INIS)

    Alloy 690 having excellent corrosion resistance is widely used for SG tubes. The intergranular corrosion and pitting corrosion resistance of Baosteel's alloy 690 tube, Country A alloy 690 tube and Country B alloy 690 tube have been analysed by comparison. It shows that: The intergranular corrosion of Baosteel's alloy 690 tube tested complied with ASTM G28 Standard could satisfy the technical requirement. However.some of Baosteel's alloy 690 tube in intergranular corrosion resistance had less performance than Country A. In addition, pitting corrosion tested with ASTM G48 Standard shown the Baosteel's alloy 690 tube better than Country B. (authors)

  2. Performance analysis of wick-assisted heat pipe solar collector and comparison with experimental results

    Science.gov (United States)

    Azad, E.

    2009-03-01

    The performance of heat pipe solar collector is investigated theoretically and experimentally. The system employs wick-assisted heat pipe for the heat transfer from the absorber (evaporator) to a heat exchanger (condenser). The heat pipe is made with a copper tube and the evaporator section is finned with aluminium plate. Theoretical model predicts the outlet water from heat exchanger, heat pipe temperature and also the thermal efficiency of solar collector. The results are compared with experimental data.

  3. Whole shaft visibility and mechanical performance for active MR catheters using copper-nitinol braided polymer tubes

    Directory of Open Access Journals (Sweden)

    McVeigh Elliot R

    2009-08-01

    Full Text Available Abstract Background Catheter visualization and tracking remains a challenge in interventional MR. Active guidewires can be made conspicuous in "profile" along their whole shaft exploiting metallic core wire and hypotube components that are intrinsic to their mechanical performance. Polymer-based catheters, on the other hand, offer no conductive medium to carry radio frequency waves. We developed a new "active" catheter design for interventional MR with mechanical performance resembling braided X-ray devices. Our 75 cm long hybrid catheter shaft incorporates a wire lattice in a polymer matrix, and contains three distal loop coils in a flexible and torquable 7Fr device. We explored the impact of braid material designs on radiofrequency and mechanical performance. Results The incorporation of copper wire into in a superelastic nitinol braided loopless antenna allowed good visualization of the whole shaft (70 cm in vitro and in vivo in swine during real-time MR with 1.5 T scanner. Additional distal tip coils enhanced tip visibility. Increasing the copper:nitinol ratio in braiding configurations improved flexibility at the expense of torquability. We found a 16-wire braid of 1:1 copper:nitinol to have the optimum balance of mechanical (trackability, flexibility, torquability and antenna (signal attenuation properties. With this configuration, the temperature increase remained less than 2°C during real-time MR within 10 cm horizontal from the isocenter. The design was conspicuous in vitro and in vivo. Conclusion We have engineered a new loopless antenna configuration that imparts interventional MR catheters with satisfactory mechanical and imaging characteristics. This compact loopless antenna design can be generalized to visualize the whole shaft of any general-purpose polymer catheter to perform safe interventional procedures.

  4. Morphological Considerations of Fish Fin Shape on Thrust Generation

    Directory of Open Access Journals (Sweden)

    Kenji Kikuchi

    2014-01-01

    Full Text Available In this study, we aimed to determine the relationship between thrust generation and fish fin shape. To compare the effect fin shape had on thrust generation, we categorized the morphological shapes of fish fins into equilateral polygonal shapes. Polygonal fins were used to generate thrust that depended only on shape. These fins were constructed of a hard elastic material to eliminate any influence of shape deformation. A servomotor with a reciprocal rotation moved a fin cyclically, and thrust was experimentally measured using a strain gage system. Thrust tended to be proportional to the inertia moment of a fin, which indicated difficulty with rotation. Moreover, this trend for thrust generation was directly related to the number of apexes of a polygonal fin. The force translated ratio, which was thrust divided by the force required for fin rotation, was evaluated to determine the hydrodynamic characteristics of fins. This finding showed that the force translated ratio of a fin increased with increased movable perimeter length. The greatest thrust was generated by a triangular fin rotated at its apex, which is often seen in general fish tail fins, whereas the hydrodynamic characteristics were the worst in polygonal fins.

  5. Pressing og finned pipes on horizontal presses and their cold calibration

    International Nuclear Information System (INIS)

    Manufacturing of fin tubes (42x5x72 mm from 12Kh1MF steel, 50x5x70 mm from 20 steel and 60x6x80 mm from steel 20 and 15KhM) by hot pressing on horizontal hydraulic presses was studied. Temperature an strain rate were chosen so as to provide standard quality of the tubes without subsequent thermal treatment. Statistical analysis was used to determine wear of the technological instruments under different conditions of pressing. Optimum size and resistance of the instruments were determined. Optimum conditions of strain were derived from metallographyc studies. Also studied was the cold frameless gauging of the tubes and the range of its applicability

  6. Fabrication and Evaluation of SFR Cladding Tubes

    International Nuclear Information System (INIS)

    Summary: • Development of advanced FM steels: – 9Cr-2W-TaVNbB. • Fabrication and evaluation of cladding tubes: – HT9 and Gr.92 cladding tube fabrication; – Creep, tensile, burst, and microstructure; – HT9 cladding tube fabricated in Korea showed similar mechanical properties with the data in the literature. • Future works: – Fabrication of cladding tubes with new alloys; – Performance of out-of-pile test; – Fast neutron irradiation test

  7. photomultiplier tube

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  8. photomultiplier tubes

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  9. Temperature-time distribution and thermal stresses on the RTG fins and shell during water cooling

    Science.gov (United States)

    Turner, R. H.

    1983-01-01

    Radioisotope thermoelectric generator (RTG) packages designed for space missions generally do not require active cooling. However, the heat they generate cannot remain inside of the launch vehicle bay and requires active removal. Therefore, before the Shuttle bay door is closed, the RTG coolant tubes attached to the heat rejection fins must be filled with water, which will circulate and remove most of the heat from the cargo bay. There is concern that charging a system at initial temperature around 200 C with water at 24 C can cause unacceptable thermal stresses in the RTG shell and fins. A computer model is developed to estimate the transient temperature distribution resulting from such charging. The thermal stresses resulting from the temperature gradients do not exceed the elastic deformation limit for the material. Since the simplified mathematical model for thermal stresses tends to overestimate stresses, it is concluded that the RTG can be cooled by introducing water at 24 C to the initially hot fin coolant tubes while the RTG is in the Shuttle cargo bay.

  10. Detection of early stages of Myxobolus cerebralis in fin clips from rainbow trout (Orynchus mykiss).

    Science.gov (United States)

    Skirpstunas, Ramona T; Hergert, John M; Baldwin, Thomas J

    2006-05-01

    A nested polymerase chain reaction (PCR) assay was used to detect early stages of Myxobolus cerebralis in caudal and adipose fin samples from rainbow trout (RT). To determine sensitivity, groups of 10 RT were exposed to 2,000 M. cerebralis triactinomyxons/fish for 1 hour at 15 degrees C and subsequently moved to clean recirculating water. Fish were held for 2 and 6 hours and 1, 2, 3, 5, 7, 10, 30, and 60 days before sampling by nonlethal fin biopsy. Nested PCR performed on fin clips showed that M. cerebralis DNA was detected in caudal fin tissue in 100% of fish up to 5 days postexposure. At days 7 and 10 postexposure, 80% of fish were positive, and at 60 days postexposure, 60% of fish were positive using this technique. Conversely, testing on adipose fin clips proved less sensitive, as positive fish dropped from 80% at day 7 to below 20% at day 10 postinfection. Since detection of M. cerebralis infection using caudal fin samples coupled with nested PCR is an effective method for detection of early parasite stages, use of this technique provides for accurate, nonlethal testing. PMID:16789717

  11. Cooling Effect Improvement by Dimensional Modification of Annular Fins in Two Stage Reciprocating Compressor

    Directory of Open Access Journals (Sweden)

    Mr. Ashish D. Vasiyar,

    2014-05-01

    Full Text Available The Reciprocating Compressor fins are made from Aluminum alloy and it is provided for increase in contact area in convective heat transfer. Air cooling is a method of dissipating heat It works by making the object to be cooled have a larger surface area or have an increased flow of air over its surface. a fin is a surface that extends from an object to increase the rate of heat transfer to or from the environment by increasing convection. The aim of present work study is to prepare a finite element model of fin. The result of finite element model will be verified with experimental work with thermocouple. After comparing results of FEA model we can modify boundary condition, material shape & size for improvement in efficiency & cooling rate. It is possible to find optimum solution with FEA package ANSYS 14 used for modeling and analysis. Effectiveness of fin can be improved by changing geometry of fin. So after increase effectiveness it can increase cooling rate and minimize the time for cooling process of Reciprocating compressor. Aim of this work is increase effectiveness of the fin for best performance.

  12. Pool boiling on surfaces with mini-fins and micro-cavities

    International Nuclear Information System (INIS)

    The experimental studies presented here focused on pool boiling heat transfer on mini-fin arrays, mini-fins with perforated covering and surfaces with micro-cavities. The experiments were carried out for water and fluorinert FC-72 at atmospheric pressure. Mini-fins of 0.5 and 1 mm in height were uniformly spaced on the base surface. The copper foil with holes of 0.1 mm in diameter (pitch 0.2/0.4 mm), sintered with the fin tips, formed a system of connected perpendicular and horizontal tunnels. The micro-cavities were obtained through spark erosion. The maximal depth of the craters of these cavities was 15 – 30 ?m and depended on the parameters of the branding-pen settings. At medium and small heat fluxes, structures with mini-fins showed the best boiling heat transfer performance both for water and FC-72. At medium and high heat fluxes (above 70 kW/m2 for water and 25 kW/m2 for FC-72), surfaces with mini-fins without porous covering and micro-cavities produced the highest heat transfer coefficients. The surfaces obtained with spark erosion require a proper selection of geometrical parameters for particular liquids – smaller diameters of cavities are suitable for liquids with lower surface tension (FC-72).

  13. Liquid-metal pin-fin pressure drop by correlation in cross flow

    International Nuclear Information System (INIS)

    The pin-fin configuration is widely used as a heat transfer enhancement method in high-heat-flux applications. Recently, the pin-fin design with liquid-metal coolant was also applied to synchrotron-radiation beamline devices. This paper investigates the pressure drop in a pin-post design beamline mirror with liquid gallium as the coolant. Because the pin-post configuration is a relatively new concept, information in literature about pin-post mirrors or crystals is rare, and information about the pressure drop in pin-post mirrors with liquid metal as the coolant is even more sparse. Due to this the authors considered the cross flow in cylinder-array geometry, which is very similar to that of the pin-post, to examine the pressure drop correlation with liquid metals over pin fins. The cross flow of fluid with various fluid characteristics or properties through a tube bank was studied so that the results can be scaled to the pin-fin geometry with liquid metal as the coolant. Study lead to two major variables to influence the pressure drop: fluid properties, viscosity and density, and the relative length of the posts. Correlation of the pressure drop between long and short posts and the prediction of the pressure drop of liquid metal in the pin-post mirror and comparison with an existing experiment are addressed

  14. Fabrication of AlGaN/GaN ?-shaped nanowire fin-shaped FETs by a top-down approach

    Science.gov (United States)

    Im, Ki-Sik; Sindhuri, Vodapally; Jo, Young-Woo; Son, Dong-Hyeok; Lee, Jae-Hoon; Cristoloveanu, Sorin; Lee, Jung-Hee

    2015-06-01

    An AlGaN/GaN-based ?-shaped nanowire fin-shaped FET (FinFET) with a fin width of 50 nm was fabricated using tetramethylammonium hydroxide (TMAH)-based lateral wet etching. An atomic layer deposited (ALD) HfO2 side-wall layer served as the etching mask. ALD Al2O3 and TiN layers were used as the gate dielectric and gate metal, respectively. The ?-shaped gate structure fully depletes the active fin body and almost completely separates the depleted fin from the underlying thick GaN buffer layer, resulting in superior device performance. The top-down processing proposed in this work provides a viable pathway towards gate-all-around devices for III–nitride semiconductors.

  15. Tapered pulse tube for pulse tube refrigerators

    Science.gov (United States)

    Swift, Gregory W. (Sante Fe, NM); Olson, Jeffrey R. (San Mateo, CA)

    1999-01-01

    Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

  16. Feedwater heater tube material study

    International Nuclear Information System (INIS)

    Despite the many developmental efforts, no feedwater heater (FWH) tube material is available which ideally combines all desirable characteristics and cost-effectiveness. Several FWH tube materials have been used by the US utilities. Almost all of these materials have some disadvantages associated with them. Nevertheless, proper application of materials, stringent purchase specifications and adequate water chemistry control can insure high FWH reliability. During the past several years, copper based alloys were widely used as the FWH tube material in the high chloride and high ammonia environment of the coastal power plants of the Southern electric system. They have generally performed well. But the current industry trend is to move away from these copper alloys because: (1) copper contamination of the steam supply system is detrimental to the boiler and turbine components; (2) copper alloys place limits on water chemistry at the expense of ferrous components; (3) presence of ammonia can cause tube failures in copper alloys; and (4) US production capacity of copper based tubes is shrinking. The objective of this study is to evaluate tube materials for FWHs located at these coastal power plants. Vendor data, industry literature and field experience of electric utilities are used to compare budget pricing, heater sizes and mechanical properties of various tube materials. Based on plant data, an attempt is made to quantify chloride leaks. In addition to chlorides, other we leaks. In addition to chlorides, other water chemistry information from these plants is used to evaluate suitability of various tube materials. 8 refs., 2 figs., 3 tabs

  17. Exotic wakes of flapping fins

    DEFF Research Database (Denmark)

    Schnipper, Teis

    2011-01-01

    We present, in 8 chapters, experiments on and numerical simulations of bodies flapping in a fluid. Focus is predominantly on a rigid foil, a model fish, that performs prescribed pitching oscillations where the foil rotates around its leading edge. In a flowing soap film is measured, with unprecedented accuracy, the vortex wake structure behind the flapping foil in the space spanned by dimensionless flapping frequency 0

  18. Research on heat transfer enhancement of vapour condensation in vertical tubes

    International Nuclear Information System (INIS)

    This paper is aimed at the enhancing the condensation heat transfer in the passive emergency condenser of the Third Generation Advanced Reactor. The characteristics of complete condensation heat transfer of saturated vapor in vertical smooth, straight fin and helical micro-fin tube with helix angle 30? was studied. The outer diameters of all the three tubes are 16 mm, and the saturation pressure ranges from 0.14 MPa to 0.4 MPa. It is showed that, within the experimental ranges, heat transfer coefficient of helical tube is 2.7?3.2 times, and for straight fin tube, 2.8?3.3 times as high as that of smooth tube. Heat transfer coefficient of smooth tube decreases slightly with the increase of temperature difference, while for the complete condensation inside the micro-fin tubes, it increases at first, and then decreases while the temperature difference is exceeding a certain value. We found that the main reason leading to the lowering of heat transfer ability is that heat resistance increases with increasing of the thickness of condensed liquid film. (authors)

  19. Numerical Analysis and Optimization of Engine Cylinder Fins of Varying

    OpenAIRE

    Saravanan*1,

    2014-01-01

    The main aim of the project is to analyze the thermal properties by varying geometry, material and thickness of cylinder fins. Parametric models of cylinder with fins have been developed to predict the transient thermal behavior. The models are created by varying the geometry, rectangular, circular and curved shaped fins and also by varying thickness of the fins. The 3D modeling software used is Pro/Engineer.The analysis is done using ANSYS. Presently Material used for manufac...

  20. Fire testing of an intumescent coating on a finned surface

    International Nuclear Information System (INIS)

    A series of fire tests have been carried out to test the effectiveness of an intumescent coating in reducing the heat flux into a finned surface. The coating was applied only to the base of the fin cavity so as not to significantly impair heat transfer under normal conditions. When subjected to a fire the intumescent coating swelled up to fill most of the fin cavity and reduced the heat flux into the finned surface by over 50%. (author)

  1. Enhancing Heat Removal by Optimizing Fin Configuration in Air Compressor

    OpenAIRE

    P.Ragupathi*1; Dr.V.R.Sivakumar2

    2014-01-01

    This project deals with finding the optimum fin shape and size for the better heat removal from the compressor surface. Various parameters such as fin configuration, fin thickness, length, and number of fins are taken for optimization. Overheating and excess heating causes uneven thermal loading on the compressor surface. This thermally induced stresses can couple with pressure induced stresses and can abruptly alter the life of compressor. Increasing the convective heat trans...

  2. Experimental investigation and exergy analysis of the performance of a counter flow Ranque-Hilsch vortex tube with regard to nozzle cross-section areas

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, K.; Avci, A.; Berber, A. [Dept. of Mechanical Eng., Fac. of Eng. and Architecture, Selcuk Univ., Selcuklu, Konya (Turkey); Baskaya, S. [Dept. of Mechanical Eng., Fac. of Eng. and Architecture, Gazi Univ., Maltepe, Ankara (Turkey)

    2010-08-15

    Exergy analysis and performance of a Ranque-Hilsch Vortex Tube (RHVT) with various nozzle cross-section areas (NCSA = 3 x 3, 4 x 4, 5 x 5 mm{sup 2}) were determined under inlet pressures (P{sub i}) of 260, 300 kPa (absolute) pressurized air. The maximum difference in the temperatures of hot output and cold output streams was obtained for NCSA = 3 x 3 mm{sup 2}. The total inlet exergy (sum E{sub i}), total outlet exergy (sum E{sub O}), total lost exergy (sum E{sub Lost}) and exergy efficiency ({eta}, %) were calculated. It was determined that the exergy efficiency of the system, varied between 1% and 39%, and the highest exergy efficiency was obtained for NCSA = 3 x 3 mm{sup 2}. The exergy efficiency strongly depends on the level of P{sub i}, {xi} and v{sub cold}. Variation of the exergy efficiency decreased with decreasing P{sub i}, {xi}, v{sub cold} and the highest and lowest exergy efficiencies were found when the values of P{sub i}, {xi}, v{sub cold} reached maximum and minimum levels, respectively. (author)

  3. Volumetric low-tube-voltage CT imaging for evaluating hypervascular hepatocellular carcinoma. Effects on radiation exposure, image quality, and diagnostic performance

    International Nuclear Information System (INIS)

    The objectives of this study were to assess the value of hepatic arterial-phase (HAP) imaging with a low tube voltage (80 kVp), using non-helical, volumetric acquisition with a 320-detector-rows area-detector CT (ADCT) scanner for evaluating hypervascular hepatocellular carcinoma (HCC) compared with routine 120-kVp HAP imaging. This study enrolled 128 patients with 148 HCCs. Seventy-six patients with 79 HCCs underwent HAP imaging with 80 kVp obtained using a 320-detector-rows ADCT scanner. The remaining 52 patients with 69 HCCs underwent routine HAP imaging with 120 kVp obtained by 64-slice helical acquisition. Image noise and tumor to liver contrast-to-noise ratio (CNR) of the two sets of images were compared. Three radiologists evaluated both sets of images using receiver operating characteristic analyses. Although there was a two-fold increase in the mean image noise with 80 kVp over that with 120 kVp (p<0.001), no significant differences were observed in CNR among the two sets. The mean area under the curve (Az value) and the sensitivity for detecting HCC with 80 kVp (0.980, 78/79, respectively) were higher than that of 120 kVp (0.892, 55/69, respectively). HAP imaging with 80 kVp obtained by an ADCT scanner significantly improves the diagnostic performance for evaluating hypervascular HCC. (author)

  4. Liquid-crystal display monitors and cathode-ray tube monitors: a comparison of observer performance in the detection of small solitary pulmonary nodules

    International Nuclear Information System (INIS)

    To compare observer performance using liquid-crystal display (LCD) and cathode-ray tube (CRT) monitors in the interpretation of soft-copy chest radiographs for the detection of small solitary pulmonary nodules. By reviewing our Medical Center's radiologic information system, the eight radiologists participating in this study (three board-certified and five resident) retrospectively collected 40 chest radiographs showing a solitary noncalcified pulmonary nodule approximately 1 cm in diameter, and 40 normal chest radiographs. All were obtained using a storage-phosphor system, and CT scans of the same patients served as the gold standard for the presence of a pulmonary nodule. Digital images were displayed on both high-resolution LCD and CRT monitors. The readers were requested to rank each image using a fivepoint scale (1 = definitely negative, 3 = equivocal or indeterminate, 5 definitely positive), and the data were interpreted using receiver operating characteristic (ROC) analysis. The mean area under the ROC curve was 0.8901± 0.0259 for the LCD session, and 0.8716± 0.0266 for the CRT session (p>0.05). The reading time for the LCD session was not significantly different from that for the CRT session (37.12 and 41.46 minutes, respectively; p=0.889). For detecting small solitary pulmonary nodules, an LCD monitor and a CRT monitor are comparable

  5. Design, fabrication, and performance of brazed, graphite electrode, multistage depressed collectors with 500-W, continuous wave, 4.8- to 9.6-GHz traveling-wave tubes

    Science.gov (United States)

    Ramins, Peter; Ebihara, Ben

    1989-03-01

    A small, isotropic graphite electrode, multistage depressed collector (MDC) was designed, fabricated, and evaluated in conjunction with a 500-W, continuous wave (CW), 4.8- to 9.6-GHz traveling-wave tube (TWT). The carbon electrode surfaces were used to improve the TWT overall efficiency by minimizing the secondary electron emission losses in the MDC. The design and fabrication of the brazed graphite MDC assembly are described. The brazing technique, which used copper braze filler metal, is compatible with both vacuum and the more commonly available hydrogen atmosphere brazing furnaces. The TWT and graphite electrode MCC bakeout, processing, and outgassing characteristics were evaluated and found to be comparable to TWT's equipped with copper electrode MDC's. The TWT and MDC performance was optimized for broadband CW operation at saturation. The average radiofrequency (RF), overall, and MDC efficiencies were 14.9, 46.4, and 83.6 percent, respectively, across the octave operating band. A 1500-hr CW test, conducted without the use of an appendage ion pump, showed no gas buildup and excellent stability of the electrode surfaces.

  6. Study on transport safety of fresh MOX fuel. Performance of the cladding tube of fresh MOX fuel against external water pressure

    International Nuclear Information System (INIS)

    It is important to know the ability of the cladding tube for fresh MOX fuel against external water pressure when they were hypothetically sunk into the sea for unknown reasons. In order to evaluate the ability of cladding tubes for MOX fresh fuel against external water pressure, external water pressure tests were carried out. Resistible limit of cladding tubes against external water pressure is defined when cladding tubes are deformed largely due to buckling etc. The test results show cladding tube of BWR type can resist an external water pressure of 69 MPa (a depth of water of 7,000 m) and that of PWR type fuel can resist an external water pressure of 54 MPa (a depth of water of 5,500 m). Moreover, leak tightness is maintained at an external water pressure of 73 MPa (a depth of water of 7,400 m) for BWR type cladding tubes and at an external water pressure of 98 MPa (a depth of water of 10,000 m) for PWR type cladding tubes. (author)

  7. Tube bundle heat exchanger

    International Nuclear Information System (INIS)

    The heat exchanger consists of tube bundles mounted in parallel. Each bundle consists of a jacket in which tubes for a first coolant are mounted. Straight tubes are connected with their open ends to tube plates which, in turn, are connected to the jacket provided with the inlet and outlet for a second coolant. This passes between the outer surfaces of straight tubes and the inner jacket surface. Spacers are inserted between the tube bundles, this along the whole length of the bundles. The second coolant enters one tube plate through the open ends of inlet tubes. It leaves through the other tube plate of the respective bundle, through the open ends of the outlet tubes. The other open ends of the inlet and/or outlet tubes are inserted in auxiliary tube plates mounted in the jacket on both sides of the tube bundles. (H.S.)

  8. Comparative Experimental Analysis of the Thermal Performance of Evacuated Tube Solar Water Heater Systems With and Without a Mini-Compound Parabolic Concentrating (CPC) Reflector(C < 1)

    OpenAIRE

    Yuehong Su; Gang Pei; Guiqiang Li; Xi Zhou; Jie Ji

    2012-01-01

    Evacuated tube solar water heater systems are widely used in China due to their high thermal efficiency, simple construction requirements, and low manufacturing costs. CPC evacuated tube solar water heaters with a geometrical concentration ratio C of less than one are rare. A comparison of the experimental rig of evacuated tube solar water heater systems with and without a mini-CPC reflector was set up, with a series of experiments done in Hefei (31°53'N, 117°15'E), China. The first and sec...

  9. Duplication of the fallopian tube

    Directory of Open Access Journals (Sweden)

    Narayanan R

    2008-01-01

    Full Text Available Hysterosalpingography accurately delineates the uterine and tubal lumen, and hence is routinely performed for the evaluation of infertility.We observed a case of infertility where uterine cavity was normal but fallopian tubes were bifurcated at the ampullary region. Mullerian duct anomalies are reported in literature, but maldevelopment of fallopian tube in isolation is rare. This abnormality can present as infertility, ectopic pregnancy, in association with urinary tract anomalies or as failure of sterilisation method.

  10. Germanium Nanowires-in-Graphite Tubes via Self-Catalyzed Synergetic Confined Growth and Shell-Splitting Enhanced Li-Storage Performance.

    Science.gov (United States)

    Sun, Yong; Jin, Shuaixing; Yang, Guowei; Wang, Jing; Wang, Chengxin

    2015-04-28

    Despite the high theoretical capacity, pure Ge has various difficulties such as significant volume expansion and electron and Li(+) transfer problems, when applied as anode materials in lithium ion battery (LIB), for which the solution would finally rely on rational design like advanced structures and available hybrid. Here in this work, we report a one-step synthesis of Ge nanowires-in-graphite tubes (GNIGTs) with the liquid Ge/C synergetic confined growth method. The structure exhibits impressing LIB behavior in terms of both cyclic stability and rate performance. We found the semiclosed graphite shell with thickness of ?50 layers experience an interesting splitting process that was driven by electrolyte diffusion, which occurs before the Ge-Li alloying plateau begins. Two types of different splitting mechanism addressed as "inside-out"/zipper effect and "outside-in" dominate this process, which are resulted from the SEI layer growing longitudinally along the Ge-graphite interface and the lateral diffusion of Li(+) across the shell, respectively. The former mechanism is the predominant way driving the initial shell to split, which behaves like a zipper with SEI layer as invisible puller. After repeated Li(+) insertion/exaction, the GNIGTs configuration is finally reconstructed by forming Ge nanowires-thin graphite strip hybrid, both of which are in close contact, resulting in enormous enchantment to the electrons/Li(+) transport. These features make the structures perform well as anode material in LIB. We believe both the progress in 1D assembly and the structure evolution of this Ge-C composite would contribute to the design of advanced LIB anode materials. PMID:25738797

  11. Performance of QuantiFERON-TB Gold In-Tube test and Tuberculin Skin Test for diagnosis of latent tuberculosis infection in BCG vaccinated health care workers

    Science.gov (United States)

    Babayigit, Cenk; Ozer, Burcin; Inandi, Tacettin; Ozer, Cahit; Duran, Nizami; Gocmen, Orhan

    2014-01-01

    Background Tuberculin skin test (TST) has been used for years as an aid in diagnosing latent tuberculosis infection (LTBI) but it suffers from a number of well-documented performance and logistic problems. Quantiferon-TB Gold In Tube test (QFT-GIT) has been reported to have better sensitivity and specifity than TST. In this study, it was aimed to compare the performance of a commercial IFN-? release assay (QFT-GIT) with TST in the diagnosis of HCWs at risk for latent TB infection in BCG vaccinated population. Material/Methods Hundred healthy volunteer health care workers were enrolled. All were subjected to TST and QFT-GIT. Results were compared among Health Care Workers (HCWs) groups in terms of profession, workplace, working duration. Results TST is affected by previous BCG vaccinations and number of cases with QFT-GIT positivity is increased in accordance with the TST induration diameter range. QFT-GIT result was negative in 17 of 32 TST positive (?15 mm) cases and positive in 4 of 61 cases whose TST diameters are between 6–14 mm, that is attritutable to previous BCG vaccination(s). It was negative in all cases with TST diameters between 0–5 mm. HCWs with positive QFT-GIT results were significantly older than the ones with negative results. Furthermore duration of work was significantly longer in QFT-GIT positive than in negative HCWs. Conclusions There was a moderate concordance between QFT-GIT and TST, when TST result was defined as positive with a ?15 mm diameter of induration. We suggest that QFT-GIT can be used as an alternative to TST for detection of LTBI, especially in groups with high risk of LTBI and in population with routine BCG vaccination program. PMID:24681806

  12. Preparation of CdS NCs decorated TiO2 nano-tubes arrays photoelectrode and its enhanced photoelectrocatalytic performance and mechanism

    International Nuclear Information System (INIS)

    CdS nano-crystallites decorated TiO2 nano-tubes arrays (CdS NCs/TiO2 NTAs) photoelectrodes were prepared through anodization, followed by electrodeposition strategy. Subsequently, structures of the resulting CdS NCs/TiO2 NTAs samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). In addition, the light absorption capacities and photoelectrochemical (PECH) properties were investigated through UV–visible diffuse reflectance spectrum (DRS), photocurrent response (PCR) and open-circuit photovoltage (OCP). Furthermore, photodecomposition performances were evaluated by the yield of ·OH radicals and photoelectrocatalytic (PEC) degradation of rhodamine B (RhB) under Xenon light irradiation. Moreover, the enhanced PC mechanism was proposed and confirmed through photoluminescence (PL) spectra and contribution of different reactive species. Results showed that hexagonal CdS NCs with uniform spherical sizes of 20 nm were successfully deposited onto the surface of highly ordered TiO2 NTAs, which could not only red-shift the light absorption to visible region between 400 and 700 nm, but also significantly enhance the generation of ·OH radicals. Furthermore, CdS NCs/TiO2 NTAs photoelectrodes possessed higher transient photogenerated current of 9.62 mA cm?2 and open-circuit photovoltage of ?0.253 V cm?2 than that of bare TiO2 NTAs. Moreover, when external potential (?2 V) was applied, CdS NCs/TiO2 TNTAs samples performed higher PEC efficiency of 91.6%, which could be attributed to the intense light harvesting in visible region and high mobility and separation efficiency of photogenerated charge carriers

  13. Novel 14-nm Scallop-Shaped FinFETs (S-FinFETs) on Bulk-Si Substrate.

    Science.gov (United States)

    Xu, Weijia; Yin, Huaxiang; Ma, Xiaolong; Hong, Peizhen; Xu, Miao; Meng, Lingkuan

    2015-12-01

    In this study, novel p-type scallop-shaped fin field-effect transistors (S-FinFETs) are fabricated using an all-last high-k/metal gate (HKMG) process on bulk-silicon (Si) substrates for the first time. In combination with the structure advantage of conventional Si nanowires, the proposed S-FinFETs provide better electrostatic integrity in the channels than normal bulk-Si FinFETs or tri-gate devices with rectangular or trapezoidal fins. It is due to formation of quasi-surrounding gate electrodes on scalloping fins by a special Si etch process. The entire integration flow of the S-FinFETs is fully compatible with the mainstream all-last HKMG FinFET process, except for a modified fin etch process. The drain-induced barrier lowering and subthreshold swing of the fabricated p-type S-FinFETs with a 14-nm physical gate length are 62 mV/V and 75 mV/dec, respectively, which are much better than those of normal FinFETs with a similar process. With an improved short-channel-effect immunity in the channels due to structure modification, the novel structure provides one of possibilities to extend the FinFET scalability to sub-10-nm nodes with little additional process cost. PMID:26055484

  14. Numerical simulation and optimization of impingement cooling for rotating and stationary pin–fin heat sinks

    International Nuclear Information System (INIS)

    Highlights: • The cooling performance comparisons of air jet impingement are including rotating and stationary heat sink. • Four fluid turbulent models are implemented to compare the performance with experimental data. • The combined optimization of response surface methodology (RSM) and genetic algorithm (GA) are discussed in present study. -- Abstract: The turbulent fluid flow and heat transfer characteristics of air jet impingement onto the rotating and stationary heat sink have been investigated numerically and optimized using genetic algorithms (GAs). The squared heat sinks with uniform 5 × 5 pin–fins are employed. The turbulent governing equations are solved by using the finite volume method combined with the approaches of four different turbulent models based on the Reynolds-averaged Navier–Stokes (RANS). The relative performance of four turbulent models for predicting this type of flow and heat transfer is investigated by comparing the numerical results with available experimental data. It is found that the standard k–? model can give predictions for better performance of fluid flow and heat transfer. Studied parameters are included the distance of nozzle to fin tip (0?C/d?11), Reynolds number (5019?Re?25,096) and rotational Reynolds number (0?Rer?8114). It is found that Nu0? increases with Re for a stationary heat sink. The effects of Rer on the average Nusselt number (Nu??) of a rotating heat sink with jet impingement demonstrate that heat transfer enhancement (Nu??/Nu0?) is obvious in the case of smaller Re (Re = 5019), but Nu??/Nu0? decreased with increasing Re. In addition, the optimization of this problem is also presented by using response surface methodology (RSM) and genetic algorithm (GA) method. Three design variables including the distance of nozzle to fin tip, fin height and fin width are selected for optimization. Based on the results, the optimum condition is C/d = 0, w/d=0.77 and Hf/d=3.08 for a stationary and a rotating pin–fins heat sink

  15. Useful Scaling Parameters for the Pulse Tube

    Science.gov (United States)

    Lee, J. M.; Kittel, P.; Timmerhaus, K. D.; Radebaugh, R.; Cheng, Pearl L. (Technical Monitor)

    1995-01-01

    A set of eight non-dimensional scaling parameters for use in evaluating the performance of Pulse Tube Refrigerators is presented. The parameters result after scaling the mass, momentum and energy conservation equations for an axisymmetric, two-dimensional system. The physical interpretation of the parameters are described, and their usefulness is outlined for the enthalpy flow tube (open tube of the pulse tube). The scaling parameters allow the experimentalist to characterize three types of transport: enthalpy flow, mass streaming and heat transfer between the gas and the tube. Also reported are the results from a flow visualization experiment in which steady mass streaming in compressible oscillating flow is observed.

  16. The optimization of longitudinal convective fins with internal heat generation

    International Nuclear Information System (INIS)

    The solution of the optimization problem for longitudinal convective fins of constant thickness, triangular or parabolic profile, and uniform internal heat generation, is presented. The cases considered are those of a given heat generation density, total heat generation and heat generation per unit width of the fin, when either the heat dissipation or the width of the fin is prescribed. The results are set forth in a nondimensional form, which are presented graphically. The effect of the fin's thermal conductivity upon the optimum dimensions is discussed, and limiting values for the heat generation and the heat dissipation, which may be imposed on the fin for a feasible optimization, are also obtained. (Auth.)

  17. Heat Dissipation from a Finned Cylinder at Different Fin-Plane/Air-stream Angles

    Science.gov (United States)

    Schey, Oscar W; Biermann, Arnold E

    1932-01-01

    This report gives the results of an experimental determination of the temperature distribution in and the heat dissipation from a cylindrical finned surface for various fin-plane/air-stream angles. A steel cylinder 4.5 inches in diameter having slightly tapered fins of 0.30-inch pitch and 0.6 -inch width was equipped with an electrical heating unit furnishing 13 to 248 B.T.U. per hour per square inch of inside wall area. Air at speeds form 30 to 150 miles per hour was directed at seven different angles from 0 degrees to 90 degrees with respect to the fin planes. The tests show the best angle for cooling at all air speeds to be about 45 degrees. With the same temperature for the two conditions and with an air speed of 76 miles per hour, the heat input to the cylinder can be increased 50 percent at 45 degrees fin-plane/air-stream angle over that at 0 degrees.

  18. Template-assisted formation of microsized nanocrystalline CeO2 tubes and their catalytic performance in the carboxylation of methanol

    OpenAIRE

    Schneider, Jörg J; Naumann, Meike; Schäfer, Christian; Brandner, Armin; Heiko J. Hofmann; Claus, Peter

    2011-01-01

    Polymethylmethacrylate (PMMA)/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf) plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO2) tubes, with a diameter o...

  19. Template-assisted formation of microsized nanocrystalline CeO2 tubes and their catalytic performance in the carboxylation of methanol

    OpenAIRE

    Jörg J. Schneider; Meike Naumann; Christian Schäfer; Armin Brandner; Heiko J. Hofmann; Peter Claus

    2011-01-01

    Polymethylmethacrylate (PMMA)/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf) plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO2) tubes, with a diameter o...

  20. Emission Tube Apparatus

    Science.gov (United States)

    Dr. Charles Ward

    This is an image of an emission tube apparatus with tube in place. When plugged in and turned on the gas in the tube will become excited and emit a specific color of light depending upon the type of gas.

  1. Heat Transfer Studies in Tube Banks with Integral Wake Splitters

    Directory of Open Access Journals (Sweden)

    Suzairin Md Seri

    2009-09-01

    Full Text Available This paper reports the findings from heat transfer studies with the presence of extended surfaces from tube banks which are termed as integral wake splitter plates. Employing this type of fins, investigations on heat transfer characteristics on a single circular tube as well as tube banks were carried out in cross flow of air in a rectangular duct. Experiments were carried out in the Reynolds number range 5 x 103 to 105 on a single cylinder of various splitter length-to-tube diameter ratios, L/D = 0.5, 1.0, 1.5 and 2.0. Further, tube banks consisting of 12 rows and 3 tubes per row in equilateral triangle arrangements with transverse pitch to diameter ratio, a = 2, were also investigated, the banks being made up of plain tubes or tubes with splitters. Heat transfer characteristics were studied for tubes with L/D = 0, 0.5 and 1.0 under constant heat flux conditions. Tube banks with L/D = 1.0 yielded the highest heat transfer rates. Findings from this work may be adopted to be utilized in various industrial applications such as economizer of a steam boiler, air-conditioning coils or waste heat recovery systems.

  2. Influence of Tip Clearance on Forced Convection Heat Transfer of a Finned Plate in a Duct

    International Nuclear Information System (INIS)

    Optimizations are required for a proper enhancement of cooling capability. An important phenomenological consideration is to be reveals for a finned plate in a duct. Due to the high friction near the fin region and low friction near the wall region, the forced flow tends to bypass from fin region to wall region. The bypass flow increases the net flow and enhances the heat transfer for a moderate tip clearance which is defined by the distance from the tip of the fin and the wall. Meanwhile for a large tip clearance, most of the flow bypasses and does not contribute the heat transfer and impairs the heat transfer. This study is a preliminary numerical study on the influence of the tip clearance on the heat transfer of the finned plate in a duct. The study aimed at supporting an experimental research exploring the phenomena for a very small tip clearance. Thus material properties and test conditions were chosen to meet the experimental conditions. It investigated the phenomena at Pr of 2,014 and ReS of 58.3. In order to investigate the small tip clearance phenomena, a simple numerical scheme was developed using a commercial CFD code. A case with the same experimental condition was tested using the numerical scheme and the error was about 12%. The results show the clear evidence of the flow bypass from the fin region to wall region, which impair the heat removal capacity of the finned plate in a duct. The study has the relevance with the reactor cavity cooling system performance enhancement activities in the VHTR. The numerical scheme will be tested for narrower and wider tip clearances and find an optimal tip clearance

  3. Study for coating effect of various materials in pulse tube of pulse tube refrigerator

    Science.gov (United States)

    Ki, Taekyung; Jeong, Sangkwon

    2012-10-01

    Shuttle heat transfer loss is one of the losses generated in a pulse tube and considerably influences the performance of a pulse tube refrigerator. If the inner wall of a pulse tube is perfectly maintained at adiabatic condition, the shuttle heat transfer loss can be eliminated. Near adiabatic condition may be achieved in the inner wall of a pulse tube if it is coated by poor thermal conductor like teflon. This paper focuses on the analysis and the experimental study for the effect of coating in a pulse tube of a pulse tube refrigerator. First, the effect of coating is analyzed from the 2D numerical simulation. In this process, various artificial materials are selected as the whole component of the wall of a pulse tube and the effect of material is examined by calculating the net enthalpy flow at the cold side of the pulse tube. When the wall consists of teflon, the quantity of the net enthalpy flow is maximized among the comparison cases. Second, a pulse tube refrigerator is fabricated to confirm the actual effect of coating in the pulse tube. The inner wall of the pulse tube is coated with various materials in consideration of heat penetration depth. The cooling capacities of a pulse tube refrigerator are carefully measured and compared to examine the effect of coating. The result of this paper can be used as the practical method that improves the performance of a pulse tube refrigerator.

  4. Tube holding system

    International Nuclear Information System (INIS)

    A tube holding rig is described for the lateral support of tubes arranged in tight parcels in a heat exchanger. This tube holding rig includes not less than two tube supporting assemblies, with a space between them, located crosswise with respect to the tubes, each supporting assembly comprising a first set of parallel components in contact with the tubes, whilst a second set of components is also in contact with the tubes. These two sets of parts together define apertures through which the tubes pass

  5. Critical Heat Flux and Onset of Nucleate Boiling Tests in a Finned Rod Bundle

    International Nuclear Information System (INIS)

    Critical heat flux (CHF) tests using rod bundles were performed under low-flow conditions to supplement the CHF database for HANARO fuel. The test rod had the same geometric configuration as the HANARO fuel, and its aluminum cladding with fins was made by coextrusion on the stainless steel heating tube. Three types of test sections were used: hexagonal with seven rods, triangular with three rods, and rectangular with four rods. Each test bundle has three spacers axially, and a view window is located in the upper region of the test section. Flow patterns until the CHF condition are typically varied from bubbly flow to annular flow, and then CHF occurs through the long annular flow period. A total of 36 bundle CHF data were obtained from the 3 test sections. The results showed that the CHFs for bundles are larger than those for a single rod with the same geometrical dimension by a maximum 26% as the mass flux changes. It is considered that these results are induced by the enhancement of the turbulence and thermal mixing generated by the spacers. In addition, measurement of the onset of nucleate boiling (ONB) in the rectangular bundle was attempted using sound signals. A hydrophone was attached near the outlet wall of the test section. Hydrophone signals around the ONB point were measured and analyzed based on the frequency through the real fast Fourier transform. Frequency analysis showed clear differences in the power spectral densities for two different frequency rangdensities for two different frequency ranges before and after ONB, which verifies the usefulness of sound signals for ONB detection

  6. Teaching Shakespeare with YouTube

    Science.gov (United States)

    Desmet, Christy

    2009-01-01

    YouTube, the video sharing website that allows viewers to upload video content ranging from cute dog tricks to rare rock videos, also supports a lively community devoted to the performance of Shakespeare and Shakespearean adaptations. YouTube is also a popular site for student producers of Shakespeare performances, parodies, and other artistic…

  7. Enhanced photoelectrocatalytic performance for degradation of diclofenac and mechanism with TiO2 nano-particles decorated TiO2 nano-tubes arrays photoelectrode

    International Nuclear Information System (INIS)

    In this study, TiO2 nano-particles decorated TiO2 nano-tubes arrays (TiO2 NPs/TiO2 NTAs) photoelectrodes have been successfully prepared through anodization, combined with ultrasonic strategy, followed by annealing post-treatment. The morphology and structure of the as-prepared TiO2 NPs/TiO2 NTAs photoelectrodes were characterized by scanning electrons microscopy (SEM), N2 adsorption/desorption isotherms, X-ray diffraction (XRD) and UV–visible light diffuse reflection spectroscopy (DRS). In addition, the generation of hydroxyl radicals (·OH) was detected by a photoluminescence (PL) spectra using terephthalic acid (TA) as a probe molecule. Furthermore, the photoelectrochemical (PECH) properties of TiO2 NPs/TiO2 NTAs photoanode were investigated through transient open circuit potential (OCP), photocurrent response (PCR) and electrochemical impedance spectroscopy (EIS). It was found that TiO2 NPs/TiO2 NTAs photoelectrode exhibited a distinct decrease of OCP of ?0.219 mV cm?2 and PCR of 0.049 mA cm?2, while a significantly enhanced photoelectrocatalytic (PEC) efficiency of 63.6% (0.4 V vs. SCE) for the degradation of diclofenac. Moreover, the enhanced PEC mechanism of TiO2 NPs/TiO2 NTAs photoanode was proposed. The high PEC performance could be attributed to the decoration of TiO2 NPs, which could improve the mobility and separation efficiency of photoinduced charge carriers under external potential

  8. Experimental Investigation of Innovative Internal Trailing Edge Cooling Configurations with Pentagonal Arrangement and Elliptic Pin Fin

    Directory of Open Access Journals (Sweden)

    S. Zecchi

    2008-12-01

    Full Text Available This paper describes a heat transfer experimental study of four different internal trailing edge cooling configurations based on pin fin schemes. The aim of the study is the comparison between innovative configurations and standard ones. So, a circular pin fin configuration with an innovative pentagonal scheme is compared to a standard staggered scheme, while two elliptic pin fin configurations are compared to each other turning the ellipse from the streamwise to the spanwise direction. For each configuration, heat transfer and pressure loss measurements were made keeping the Mach number fixed at 0.3 and varying the Reynolds number from 9000 to 27000. In order to investigate the overall behavior of both endwall and pedestals, heat transfer measurements are performed using a combined transient technique. Over the endwall surface, the classic transient technique with thermochromic liquid crystals allows the measurement of a detailed heat transfer coefficient (HTC map. Pin fins are made of high thermal conductivity material, and an inverse data reduction method based on a finite element code allows to evaluate the mean HTC of each pin fin. Results show that the pentagonal arrangement generates a nonuniform HTC distribution over the endwall surface, while, in terms of average values, it is equivalent to the staggered configuration. On the contrary, the HTC map of the two elliptic configurations is similar, but the spanwise arrangement generates higher heat transfer coefficients and pressure losses.

  9. Heat transfer and pressure drop of the reactor fuel element with polyzonal spiral finning

    International Nuclear Information System (INIS)

    Heat transfer and pressure drop of the reactor fuel element with polyzonal spiral finning were investigated. Longitudinal and circumferential distributions of Sr-number of finnings in the fuel element are given. Dependences of Stkmin and Stksr on the Re number are derived. The influence of gap between two fuel elements on the heat transfer, pressure drop is presented dependent on the Re number. The influence of mutual position of flow separators of two neighbouring fuel elements on the pressure drop and heat transfer is shown as well. Investigations were performed in the range of Re numbers from 15000 to 100000

  10. Fin o metamorfosis de la escuela

    Directory of Open Access Journals (Sweden)

    José Joaquín Brunner

    1996-10-01

    Full Text Available El autor adhiere a la idea de que la escuela una es una de las matrices de la modernidad por cuanto separa la transmisión cultural de cualquier soporte físico (escritura, radicándola en el propio proceso de escolarización: su gramática consistiría en redes de clasificación del conocimiento, siendo el orden escolar esencialmente un procedimiento; el juego que juega la escuela es el de la obtención de los usos de adquisición del conocimiento. De esta forma el “fin de la escritura” como tecnología predominante del conocimiento, significara el conocimiento de una nueva era de escolarización.

  11. Design and construction of the Narusegawa bridge (fin-back bridge); Narusegawa kyoryo (fin-back kyo) no sekkei seko

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, T.; Oba, M.; Saito, K.; Sato, O. [East Japan Railway Co., Tokyo (Japan)

    1998-09-30

    This paper introduces a summary of the design and construction of the Narusegawa fin-back bridge as the world`s first railway bridge of this kind. The bridge pier shells were designed based on the explanation for the railway structure design standard by using the critical state method, and the piles, footing, and abutments were designed based on the explanation for the building design standard by using the permissible stress design method. Discussions were given on earthquakes considering the effects of the scale similar to those of the Hanshin-Awaji Great Earthquake. This bridge is a six-span continuous PRC box-type fin-back bridge. Since this bridge adopted the sponson installation method using the moving installed girders, structural analysis was performed in consideration of the installation loading and bearing with respect to structural systems by each construction step. In constructing the upper part structure, frame work equipment was suspended from the installed girders, and overhung sequentially for divided construction. Considerations were given on elastic deformation in each construction phase, and creep deformation from completion of the structural systems to the finish of the creep, and the construction was so planned that the bridge surface is level when the creep is completed. 2 refs., 8 figs., 9 tabs.

  12. Biomechanical model of batoid (skates and rays) pectoral fins predicts the influence of skeletal structure on fin kinematics: implications for bio-inspired design.

    Science.gov (United States)

    Russo, R S; Blemker, S S; Fish, F E; Bart-Smith, H

    2015-01-01

    Growing interest in the development of bio-inspired autonomous underwater vehicles (AUVs) has motivated research in understanding the mechanisms behind the propulsion systems of marine animals. For example, the locomotive behavior of rays (Batoidea) by movement of the pectoral fins is of particular interest due to their superior performance characteristics over contemporary AUV propulsion systems. To better understand the mechanics of pectoral fin propulsion, this paper introduces a biomechanical model that simulates how batoid skeletal structures function to achieve the swimming locomotion observed in nature. Two rays were studied, Dasyatis sabina (Atlantic ray), and Rhinoptera bonasus (cownose ray). These species were selected because they exhibit very different swimming styles (undulation versus oscillation), but all use primarily their pectoral fins for propulsion (unlike electric rays or guitarfishes). Computerized tomography scans of each species were taken to image the underlying structure, which reveal a complex system of cartilaginous joints and linkages. Data collected from these images were used to quantify the complete skeletal morphometry of each batoid fin. Morphological differences were identified in the internal cartilage arrangement between each species including variations in the orientation of the skeletal elements, or radials, and the joint patterns between them, called the inter-radial joint pattern. These data were used as the primary input into the biomechanical model to couple a given ray skeletal structure with various swimming motions. A key output of the model is an estimation of the uniaxial strain that develops in the skeletal connective tissue in order for the structure to achieve motions observed during swimming. Tensile load tests of this connective tissue were conducted to further investigate the implications of the material strain predictions. The model also demonstrates that changes in the skeletal architecture (e.g., joint positioning) will effect fin deformation characteristics. Ultimately, the results of this study can be used to guide the design of optimally performing bio-inspired AUVs. PMID:26079094

  13. Bearing pad to pressure tube contact simulation

    International Nuclear Information System (INIS)

    Thermal creep strain deformation is a very important pressure tube failure mechanism. During a postulated LOCA (loss of coolant accident) with failure of emergency core injection sys- tem (ECIS), the fuel cladding temperature rapidly increases and the pressure tube becomes completely dry in a few seconds after flow stagnation occurs. Subsequently, the pressure tube circumference is heated by thermal radiation except at the spots where the bearing pads are in direct contact with the pressure tube. Therefore, the localized hot spots are developed on the pressure tube's inner surface under the bearing pads. The main objective of this paper is to evaluate the local thermal-mechanical deformation of a pressure tube in a CANDU reactor and to investigate the fuel channel integrity under localized contact between bearing pad and pressure tube. Furthermore, the mechanistic models are validated against the experimental works per- formed at WRL (Whiteshell research laboratory). Calculations are performed using the finite element method in which the heat, thermal mechanical and creep strain equations are solved, simultaneously. According to the experimental set up, the heat conduction from bearing pads to the inner surface of the pressure tube with appropriate convective and radiation boundary conditions has been simulated. Furthermore, the thermal creep strain deformation has been obtained for when the pressure tube is still under operational condition. It is observed that the pressure tube thermal strain will occur if sufficient high temperature is reached however, depending on the severity of flow degradation in the fuel channel, these localized hot spots could represent a potential creep strain failure of the pressure tube. Whether the pressure tube would fail at these hot spots before contacting the calandria tube depends on the localized temperature and experienced pressure transients. Sensitivity analysis is performed in order to evaluate the contact conductance, the contact width and zircaloy surface emissivity. The pressure tube local strain is very sensitive to these parameters. (author)

  14. Experiments of CHF and ONB in a finned rod bundle under low flow and low pressure conditions

    International Nuclear Information System (INIS)

    Rod bundle CHF tests were performed under low flow conditions to supplement the CHF data for HANARO fuel. The test rod had the same geometric configuration as the real HANARO fuel and the aluminium cladding with fins is co-extruded on the stainless steel heating tube. There are 3 types of test sections of which shapes are hexagonal with 7 rods, triangular with 3 rods and rectangular with 4 rods. A test bundle has 3 spacers axially and a view window is located in the upper region of the test section. Flow patterns until the CHF condition are typically varied from bubbly flow to annular flow and then CHF occurs through the long annular flow period. A total of 36 bundle CHF data was obtained in 3 test sections. The results showed that the bundle CHF data is larger than the single rod CHF data by 4% ? 32%. It is considered that these results are induced by the enhancement of the turbulence and thermal mixing generated by the spacers. In addition, measurement of the ONB in the rectangular bundle was attempted using sound signals. A hydrophone was attached to near the outlet wall of the test section. Hydrophone signals around the ONB point were measured and analyzed based on the frequency through the real FFT. Frequency analysis showed clear differences in the PSDs for 3 different frequency ranges before and after ONB. This behaviour was reproduced for different flow rates. (author)

  15. Flat tube heat exchangers – Direct and indirect noise levels in heat pump applications

    International Nuclear Information System (INIS)

    In the outdoor unit of an air-source heat pump the fan is a major noise source. The noise level from the fan is dependent on its state of operation: high air-flow and high pressure drop often result in higher noise levels. In addition, an evaporator that obstructs an air flow is a noise source in itself, something that may contribute to the total noise level. To be able to reduce the noise level, heat exchanger designs other than the common finned round tubes were investigated in this study. Three types of heat exchanger were evaluated to detect differences in noise level and air-side heat transfer performance at varying air flow. The measured sound power level from all the heat exchangers was low in comparison to the fan sound power level (direct effect). However, the heat exchanger design was shown to have an important influence on the sound power level from the fan (indirect effect). One of the heat exchangers with flat tubes was found to have the lowest sound power level, both direct and indirect, and also the highest heat transfer rate. This type of flat tube heat exchanger has the potential to reduce the overall noise level of a heat pump while maintaining heat transfer efficiency. - Highlights: •The direct noise from a heat exchanger is negligible in heat pump applications. •The design of the heat exchanger highly influences the noise from an outdoor unit. •Flat tube heat exchangers can reduce the noise from the outdoor unit of a heat pump. •Flat tube heat exchangers can increase the energy efficiency of a heat pump

  16. Filipinas, fin de siglo: imágenes y realidad

    Directory of Open Access Journals (Sweden)

    Elizalde, María Dolores

    1998-08-01

    Full Text Available The objective of this paper is to present an image of the Philippines at the end of the 19th century, different to the picture of underveloped islands, inhabitated by savages unable to selfgovernment, transmited by the historiography and caricatures of that time. With this purpose, they are studied the process of redefinition of the Spanish colonial goverment, the strengthening of a new filipino society, the development of the economy and commerce, and the strong international interests in the islands.

    El presente artículo pretende ofrecer una imagen de las Filipinas de fin de siglo, diferente de la transmitida por la historiografía tradicional y por la viñetas y caricaturas de la época. Frente a los estereotipos de unas islas atrasadas, incapaces del autogobierno, habitadas por salvajes a los que había que civilizar, se impone una realidad definida por el gobierno colonial de España, en pleno proceso de redefinición; por el afianzamiento de una burguesía ilustrada filipina, la pujanza de una clase campesina y obrera, la fuerza de un movimiento de afirmación nacional, y el desarrollo de una economía agroexportadora en pleno crecimiento; y por la presencia de fuertes intereses internacionales que hay que entender insertos en la marea de expansión colonial y reparto de mercados y territorios ultramarinos; intereses internacionales de los que se da cuenta a través de un análisis de comercio, inversiones y presencia diplomática de las grandes potencias en las Filipinas de fin de siglo.

  17. Liquid-metal, pin-fin pressure drop by correlation in cross flow

    International Nuclear Information System (INIS)

    The pin-fin configuration is widely used in high-heat-flux applications. Recently, the pin-fin design with liquid-metal coolant was also applied to synchrotron-radiation beamline devices. This article investigates the pressure drop in a pin-post crystal with liquid gallium as the coolant. Because the pin-post configuration is a relatively new concept, information in the literature on pin-post mirrors or crystals is rare, and information on the pressure drop in pin-post mirrors with liquid metal as the coolant is even rarer. Because the cross flow in cylinder-array geometry is very similar to that of the pin post, the pressure drop correlation data for the cross flow of fluid with various fluid characteristics or properties through a tube bank are studied so that the results can be scaled to the pin-fin geometry with liquid metal as the coolant. The emphasis of this article is on the influence of two variables on the pressure drop: viscosity and density of fluid. The difference and correlation of the pressure drop between long and short posts and the predication of the pressure drop of liquid metal in the pin-post mirror and comparison with an existing experiment are addressed

  18. Hermetic Seal Designs for Sample Return Sample Tubes

    Science.gov (United States)

    Younse, Paulo J.

    2013-01-01

    Prototypes have been developed of potential hermetic sample sealing techniques for encapsulating samples in a ˜1-cm-diameter thin-walled sample tube that are compatible with IMSAH (Integrated Mars Sample Acquisition and Handling) architecture. Techniques include a heat-activated, finned, shape memory alloy plug; a contracting shape memory alloy activated cap; an expanding shape memory alloy plug; and an expanding torque plug. Initial helium leak testing of the shape memory alloy cap and finned shape memory alloy plug seals showed hermetic- seal capability compared against an industry standard of seal integrity after Martian diurnal cycles. Developmental testing is currently being done on the expanding torque plug, and expanding shape memory alloy plug seal designs. The finned shape memory alloy (SMA) plug currently shows hermetic sealing capability based on preliminary tests.

  19. Air cooling effect of fins on a Honda shine bike

    Directory of Open Access Journals (Sweden)

    Padhiyar Abhesinh J

    2015-05-01

    Full Text Available The main of aim of this work is to study various researches done in past to improve heat transfer rate of cooling fins by changing cylinder block fin geometry. Low rate of heat transfer through cooling fins is the main problem in this type of cooling. So efficiency of the engine is increase by increase the heat transfer. Examples of direct air cooling in modern automobiles are rare. The most common example is the commercials Automobile bike like a Honda Shine, Bajaj bike, Honda splendor etc. It is conclude about shape try to this fins is more effectively heat transfer in Honda shine bike compare to existing fins. After FEA Analysis it checking on fin whether efficiency of heat transfer increases or not. This work validation with Experimental and Mathematical.

  20. Methods and criteria for safety analysis (FIN L2535)

    International Nuclear Information System (INIS)

    In response to the NRC request for a proposal dated October 20, 1992, Westinghouse Savannah River Company (WSRC) submit this proposal to provide contractural assistance for FIN L2535, ''Methods and Criteria for Safety Analysis,'' as specified in the Statement of Work attached to the request for proposal. The Statement of Work involves development of safety analysis guidance for NRC licensees, arranging a workshop on this guidance, and revising NRC Regulatory Guide 3.52. This response to the request for proposal offers for consideration the following advantages of WSRC in performing this work: Experience, Qualification of Personnel and Resource Commitment, Technical and Organizational Approach, Mobilization Plan, Key Personnel and Resumes. In addition, attached are the following items required by the NRC: Schedule II, Savannah River Site - Job Cost Estimate, NRC Form 189, Project and Budget Proposal for NRC Work, page 1, NRC Form 189, Project and Budget Proposal for NRC Work, page 2, Project Description