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Sample records for film cooling performance

  1. Cooling Performance of Additively Manufactured Microchannels and Film Cooling Holes

    Science.gov (United States)

    Stimpson, Curtis K.

    Additive manufacturing (AM) enables fabrication of components that cannot be made with any other manufacturing method. Significant advances in metal-based AM systems have made this technology feasible for building production parts to be used use in commercial products. In particular, the gas turbine industry benefits from AM as a manufacturing technique especially for development of components subjected to high heat flux. It has been shown that the use of microchannels in high heat flux components can lead to more efficient cooling designs than those that presently exist. The current manufacturing methods have prevented the use of microchannels in such parts, but AM now makes them manufacturable. However, before such designs can become a reality, much research must be done to characterize impacts on flow and heat transfer of AM parts. The current study considers the effect on flow and heat transfer through turbine cooling features made with AM. Specifically, the performance of microchannels and film cooling holes made with laser powder bed fusion (L-PBF) is assessed. A number of test coupons containing microchannels were built from high temperature alloy powders on a commercially available L-PBF machine. Pressure drop and heat transfer experiments characterized the flow losses and convective heat transfer of air passing through the channels at various Reynolds numbers and Mach numbers. The roughness of the channels' surfaces was characterized in terms of statistical roughness parameters; the morphology of the roughness was examined qualitatively. Magnitude and morphology of surface roughness found on AM parts is unlike any form of roughness seen in the literature. It was found that the high levels of roughness on AM surfaces result in markedly augmented pressure loss and heat transfer at all Reynolds numbers, and conventional flow and heat transfer correlations produce erroneous estimates. The physical roughness measurements made in this study were correlated to

  2. Effects of geometry on slot-jet film cooling performance

    Energy Technology Data Exchange (ETDEWEB)

    Hyams, D.G.; McGovern, K.T.; Leylek, J.H. [Clemson Univ., SC (United States)

    1995-10-01

    The physics of the film cooling process for shaped, inclined slot-jets with realistic slot-length-to-width ratios (L/s) is studied for a range of blowing ratio (M) and density ratio (DR) parameters typical of gas turbine operations. For the first time in the open literature, the effect of inlet and exit shaping of the slot-jet on both flow and thermal field characteristics is isolated, and the dominant mechanisms responsible for differences in these characteristics are documented. A previously documented computational methodology was applied for the study of four distinct configurations: (1) slot with straight edges and sharp corners (reference case); (2) slot with shaped inlet region; (3) slot with shaped exit region; and (4) slot with both shaped inlet and exit regions. Detailed field results as well as surface phenomena involving adiabatic film effectiveness ({eta}) and heat transfer coefficient (h) are presented. It is demonstrated that both {eta} and h results are vital in the proper assessment of film cooling performance. All simulations were carried out using a multi-block, unstructured/adaptive grid, fully explicit, time-marching solver with multi-grid, local time stepping, and residual smoothing type acceleration techniques. Special attention was paid to and full documentation provided for: (1) proper modeling of the physical phenomena; (2) exact geometry and high quality grid generation techniques; (3) discretization schemes; and (4) turbulence modeling issues. The key parameters M and DR were varied from 1.0 to 2.0 and 1.5 to 2.0, respectively, to show their influence. Simulations were repeated for slot length-to-width ratio (L/s) of 3.0 and 4.5 in order to explain the effects of this important parameter. Additionally, the performance of two popular turbulence models, standard k-F, and RNG k-E, were studied to establish their ability to handle highly elliptic jet/crossflow interaction type processes.

  3. Experimental assessment of film cooling performance of short cylindrical holes on a flat surface

    Science.gov (United States)

    Singh, Kuldeep; Premachandran, B.; Ravi, M. R.

    2016-12-01

    The present study is an experimental investigation of film-cooling over a flat surface from the short cylindrical holes. The film cooling holes used in the combustion chamber and the afterburner liner of an aero engine has length-to-diameter (L/D) typically in the range 1-2, while the cooling holes used in turbine blades has L/D > 3. Based on the classification given in the literature, cooling holes with L/D ≤ 3 are named as short holes and cooling holes with L/D > 3 are named as long holes. Short film cooling holes cause jetting of the secondary fluid whereas the secondary fluid emerging from long holes has characteristics similar to fully developed turbulent flow in pipe. In order to understand the difference in the film cooling performance of long and short cooling holes, experimental study is carried out for five values of L/D in the range 1-5, five injection angles, α = 15°-90° and five mainstream Reynolds number 1.25 × 105-6.25 × 105 and two blowing ratios, M = 0.5-1.0. The surface temperature of the test plate is monitored using infrared thermography. The results obtained from the present study showed that the film-cooling effectiveness is higher for the longest holes (L/D = 5) investigated in the present work in comparison to that for the shorter holes. Short holes are found to give better effectiveness at the lowest investigated injection angle i.e. α = 15° in the near cooling hole region, whereas film cooling effectiveness obtained at injection angle, α = 45° is found to be better than other injection angles for longest investigated holes, i.e. L/D = 5.

  4. High Stability Performance of Quinary Indium Gallium Zinc Aluminum Oxide Films and Thin-Film Transistors Deposited Using Vapor Cooling Condensation Method

    Science.gov (United States)

    Lin, Yung-Hao; Lee, Ching-Ting

    2017-08-01

    High-quality indium gallium zinc aluminum oxide (IGZAO) thin films with various Al contents have been deposited using the vapor cooling condensation method. The electron mobility of the IGZAO films was improved by 89.4% on adding Al cation to IGZO film. The change in the electron concentration and mobility of the IGZAO films was 7.3% and 7.0%, respectively, when the temperature was changed from 300 K to 225 K. These experimental results confirm the high performance and stability of the IGZAO films. The performance stability mechanisms of IGZAO thin-film transistors (TFTs) were investigated in comparison with IGZO TFTs.

  5. Experimental investigation of gas turbine airfoil aerodynamic performance without and with film cooling in an annular sector cascade

    Energy Technology Data Exchange (ETDEWEB)

    Wiers, S.H.

    2002-02-01

    subject, as well as state of the art in secondary flow, single cooling jet behavior and film cooling. An overview of existing linear, annular and rotating annular test facilities is also given. The second part deals with the design and instrumentation as well as the measuring technique used for the performed investigations. Surface flow visualization has been performed to get a first idea about the secondary flow. Aerodynamic performance measurements have been conducted by means of five-hole pneumatic pressure probe traverses at 98%, 106% and 140% of c{sub ax} downstream of the cascade to gain information about the secondary flow and primary loss distribution. The variation of the Reynolds number and turbulence level show an overall loss increase for higher turbulence levels and Reynolds numbers due to higher mixing losses. Experimental investigations in terms of surface flow visualization and 5 hole pressure probe traverse of the influence of film cooling on the secondary flow effects and the losses of the cascade have been performed on a modem three dimensional nozzle guide vane with shower head cooling at the leading edge, four film cooling rows at the suction side, two film cooling rows at the pressure side and trailing edge ejection. The results of the flow visualization and pressure probe traverse show that the secondary flow region is only slightly effected by the ejection of low momentum cooling air. The cooling jets are deflected towards the hub, due to the low energy contents. With increasing mass flux ratio, respectively momentum flux ratio, the expanded secondary flow area at the trailing edge decreases. A rapid increase of the mixing loss at the midsection for ejection of high mass flow ratios in a highly accelerated flow at the suction side is observed. The coolant is seen, in every case, to increase the loss compared with the uncooled case. This is in accordance with the findings of most authors with regard to airfoil surface cooling, but the decrease in

  6. The study on the evaporation cooling efficiency and effectiveness of cooling tower of film type

    International Nuclear Information System (INIS)

    Li Yingjian; You Xinkui; Qiu Qi; Li Jiezhi

    2011-01-01

    Based on heat and mass transport mechanism of film type cooling, which was combined with an on-site test on counter flow film type cooling tower, a mathematical model on the evaporation and cooling efficiency and effectiveness has been developed. Under typical climatic conditions, air conditioning load and the operating condition, the mass and heat balances have been calculated for the air and the cooling water including the volume of evaporative cooling water. Changing rule has been measured and calculated between coefficient of performance (COP) and chiller load. The influences of air and cooling water parameters on the evaporative cooling efficiency were analyzed in cooling tower restrained by latent heat evaporative cooling, and detailed derivation and computation revealed that both the evaporative cooling efficiency and effectiveness of cooling tower are the same characteristics parameters of the thermal performance of a cooling tower under identical assumptions.

  7. Analysis of film cooling in rocket nozzles

    Science.gov (United States)

    Woodbury, Keith A.

    1993-01-01

    This report summarizes the findings on the NASA contract NAG8-212, Task No. 3. The overall project consists of three tasks, all of which have been successfully completed. In addition, some supporting supplemental work, not required by the contract, has been performed and is documented herein. Task 1 involved the modification of the wall functions in the code FDNS (Finite Difference Navier-Stokes) to use a Reynolds Analogy-based method. This task was completed in August, 1992. Task 2 involved the verification of the code against experimentally available data. The data chosen for comparison was from an experiment involving the injection of helium from a wall jet. Results obtained in completing this task also show the sensitivity of the FDNS code to unknown conditions at the injection slot. This task was completed in September, 1992. Task 3 required the computation of the flow of hot exhaust gases through the P&W 40K subscale nozzle. Computations were performed both with and without film coolant injection. This task was completed in July, 1993. The FDNS program tends to overpredict heat fluxes, but, with suitable modeling of backside cooling, may give reasonable wall temperature predictions. For film cooling in the P&W 40K calorimeter subscale nozzle, the average wall temperature is reduced from 1750R to about 1050R by the film cooling. The average wall heat flux is reduced by a factor of 3.

  8. Review on film cooling of liquid rocket engines

    Directory of Open Access Journals (Sweden)

    S.R. Shine

    2018-03-01

    Full Text Available Film cooling in combination with regenerative cooling is presently considered as an efficient method to guarantee safe operation of liquid rocket engines having higher heat flux densities for long duration. This paper aims to bring all the research carried out in the field of liquid rocket engine film cooling since 1950. The analytical and numerical procedure followed, experimental facilities and measurements made and major inferences drawn are reviewed in detail, and compared where ever possible. Review has been made through a discussion of the analyses methodologies and the factors that influence film cooling performance. An effort has also been made to determine the status of the research, pointing out critical gaps, which are still to be explained and addressed by future generations. Keywords: Heat transfer, Liquid rocket thrust chamber, Film cooling, Cooling effectiveness

  9. Effects of surface deposition and droplet injection on film cooling

    International Nuclear Information System (INIS)

    Wang, Jin; Cui, Pei; Vujanović, Milan; Baleta, Jakov; Duić, Neven; Guzović, Zvonimir

    2016-01-01

    Highlights: • Cooling effectiveness is significantly affected by the deposition size. • Coverage area for model without mist is reduced by increasing the deposition height. • Wall temperature is decreased by 15% with 2% mist injection. • Cooling coverage is increased by more than three times with 2% mist injection. • Cooling effectiveness for mist models is improved by increasing deposition height. - Abstract: In the present research, the influence of the particle dispersion onto the continuous phase in film cooling application was analysed by means of numerical simulations. The interaction between the water droplets and the main stream plays an important role in the results. The prediction of two-phase flow is investigated by employing the discrete phase model (DPM). The results present heat transfer characteristics in the near-wall region under the influence of mist cooling. The local wall temperature distribution and film cooling effectiveness are obtained, and results show that the film cooling characteristics on the downstream wall are affected by different height of surface deposits. It is also found that smaller deposits without mist injection provide a lower wall temperature and a better cooling performance. With 2% mist injection, evaporation of water droplets improves film cooling effectiveness, and higher deposits cause lateral and downstream spread of water droplets. The results indicate that mist injection can significantly enhance film cooling performance.

  10. Film cooling for a closed loop cooled airfoil

    Science.gov (United States)

    Burdgick, Steven Sebastian; Yu, Yufeng Phillip; Itzel, Gary Michael

    2003-01-01

    Turbine stator vane segments have radially inner and outer walls with vanes extending therebetween. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. At least one film cooling hole is defined through a wall of at least one of the cavities for flow communication between an interior of the cavity and an exterior of the vane. The film cooling hole(s) are defined adjacent a potential low LCF life region, so that cooling medium that bleeds out through the film cooling hole(s) reduces a thermal gradient in a vicinity thereof, thereby the increase the LCF life of that region.

  11. Turbine Airfoil Leading Edge Film Cooling Bibliography: 1972–1998

    Directory of Open Access Journals (Sweden)

    D. M. Kercher

    2000-01-01

    Full Text Available Film cooling for turbine airfoil leading edges has been a common practice for at least 35 years as turbine inlet gas temperatures and pressures have continually increased along with cooling air temperatures for higher engine cycle efficiency. With substantial engine cycle performance improvements from higher gas temperatures, it has become increasingly necessary to film cool nozzle and rotor blade leading edges since external heat transfer coefficients and thus heat load are the highest in this airfoil region. Optimum cooling air requirements in this harsh environment has prompted a significant number of film cooling investigations and analytical studies reported over the past 25 years from academia, industry and government agencies. Substantial progress has been made in understanding the complex nature of leading edge film cooling from airfoil cascades, simulated airfoil leading edges and environment. This bibliography is a report of the open-literature references available which provide information on the complex aero–thermo interaction of leading edge gaseous film cooling with mainstream flow. From much of this investigative information has come successful operational leading edge film cooling design systems capable of sustaining airfoil leading edge durability in very hostile turbine environments.

  12. Film cooling air pocket in a closed loop cooled airfoil

    Science.gov (United States)

    Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane; Bagepalli, Radhakrishna; Webbon, Waylon Willard; Burdgick, Steven Sebastian

    2002-01-01

    Turbine stator vane segments have radially inner and outer walls with vanes extending between them. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. To provide for air film cooing of select portions of the airfoil outer surface, at least one air pocket is defined on a wall of at least one of the cavities. Each air pocket is substantially closed with respect to the cooling medium in the cavity and cooling air pumped to the air pocket flows through outlet apertures in the wall of the airfoil to cool the same.

  13. Film cooling adiabatic effectiveness measurements of pressure side trailing edge cooling configurations

    Directory of Open Access Journals (Sweden)

    R. Becchi

    2015-12-01

    Full Text Available Nowadays total inlet temperature of gas turbine is far above the permissible metal temperature; as a consequence, advanced cooling techniques must be applied to protect from thermal stresses, oxidation and corrosion the components located in the high pressure stages, such as the blade trailing edge. A suitable design of the cooling system for the trailing edge has to cope with geometric constraints and aerodynamic demands; state-of-the-art of cooling concepts often use film cooling on blade pressure side: the air taken from last compressor stages is ejected through discrete holes or slots to provide a cold layer between hot mainstream and the blade surface. With the goal of ensuring a satisfactory lifetime of blades, the design of efficient trailing edge film cooling schemes and, moreover, the possibility to check carefully their behavior, are hence necessary to guarantee an appropriate metal temperature distribution. For this purpose an experimental survey was carried out to investigate the film covering performance of different pressure side trailing edge cooling systems for turbine blades. The experimental test section consists of a scaled-up trailing edge model installed in an open loop suction type test rig. Measurements of adiabatic effectiveness distributions were carried out on three trailing edge cooling system configurations. The baseline geometry is composed by inclined slots separated by elongated pedestals; the second geometry shares the same cutback configuration, with an additional row of circular film cooling holes located upstream; the third model is equipped with three rows of in-line film cooling holes. Experiments have been performed at nearly ambient conditions imposing several blowing ratio values and using carbon dioxide as coolant in order to reproduce a density ratio close to the engine conditions (DR=1.52. To extend the validity of the survey a comparison between adiabatic effectiveness measurements and a prediction by

  14. A Film-Cooling CFD Bibliography: 1971–1996

    Directory of Open Access Journals (Sweden)

    D. M. Kercher

    1998-01-01

    Full Text Available After more than 25 years of three-dimensional film cooling experimental investigations, analytical correlations and modeling, film cooling utilizing computational fluid dynamics has emerged from a similar development-applications growth process into a near-attainable heat transfer engineering tool. Analytical applications include high temperature subsonic to hypersonic flow with complex wall-geometry coolant injection film performance analysis techniques spanning usage from gas turbines to rocket engines to scramjets. In recent years there has been significant development in increased computer power and modeling capacity, increasingly more complex and successful Navier-Stokes turbulence modeling techniques, innovative labor-saving meshing techniques, and more successful validation of experimental results. These combined innovations have continued to transition computational film cooling technology from the academic, government and commercial research and development environment to the industrial design-analysis environment. This bibliography is an openliterature reference resource whose papers collectively describe the continual emerging of numerical film cooling as a viable design tool for high temperature components.

  15. Numerical investigation of unsteady mixing mechanism in plate film cooling

    Directory of Open Access Journals (Sweden)

    Shuai Li

    2016-09-01

    Full Text Available A large-scale large eddy simulation in high performance personal computer clusters is carried out to present unsteady mixing mechanism of film cooling and the development of films. Simulation cases include a single-hole plate with the inclined angle of 30° and blowing ratio of 0.5, and a single-row plate with hole-spacing of 1.5D and 2D (diameters of the hole. According to the massive simulation results, some new unsteady phenomena of gas films are found. The vortex system is changed in different position with the development of film cooling with the time marching the process of a single-row plate film cooling. Due to the mutual interference effects including mutual exclusion, a certain periodic sloshing and mutual fusion, and the structures of a variety of vortices change between parallel gas films. Macroscopic flow structures and heat transfer behaviors are obtained based on 20 million grids and Reynolds number of 28600.

  16. Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines

    Science.gov (United States)

    Micklow, Gerald J.

    1996-01-01

    The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine.

  17. The effect of freestream turbulence on film cooling adiabatic effectiveness

    International Nuclear Information System (INIS)

    Mayhew, James E.; Baughn, James W.; Byerley, Aaron R.

    2003-01-01

    The film-cooling performance of a flat plate in the presence of low and high freestream turbulence is investigated using liquid crystal thermography. This paper contributes high-resolution color images that clearly show how the freestream turbulence spreads the cooling air around a larger area of the film-cooled surface. Distributions of the adiabatic effectiveness are determined over the film-cooled surface of the flat plate using the hue method and image processing. Three blowing rates are investigated for a model with three straight holes spaced three diameters apart, with density ratio near unity. High freestream turbulence is shown to increase the area-averaged effectiveness at high blowing rates, but decrease it at low blowing rates. At low blowing ratio, freestream turbulence clearly reduces the coverage area of the cooling air due to increased mixing with the main flow. However, at high blowing ratio, when much of the jet has lifted off in the low turbulence case, high freestream turbulence turns its increased mixing into an asset, entraining some of the coolant that penetrates into the main flow and mixing it with the air near the surface

  18. Cooling Effectiveness Measurements for Air Film Cooling of Thermal Barrier Coated Surfaces in a Burner Rig Environment Using Phosphor Thermometry

    Science.gov (United States)

    Eldridge, Jeffrey I.; Shyam, Vikram; Wroblewski, Adam C.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.

    2016-01-01

    While the effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness are usually studied separately, their contributions to combined cooling effectiveness are interdependent and are not simply additive. Therefore, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. In this investigation, surface temperature mapping was performed using recently developed Cr-doped GdAlO3 phosphor thermometry. Measurements were performed in the NASA GRC Mach 0.3 burner rig on a TBC-coated plate using a scaled up cooling hole geometry where both the mainstream hot gas temperature and the blowing ratio were varied. Procedures for surface temperature and cooling effectiveness mapping of the air film-cooled TBC-coated surface are described. Applications are also shown for an engine component in both the burner rig test environment as well as an engine afterburner environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and advantages of this method over infrared thermography as well as the limitations of this method for studying air film cooling are discussed.

  19. Multidisciplinary design optimization of film-cooled gas turbine blades

    Directory of Open Access Journals (Sweden)

    Talya Shashishekara S.

    1999-01-01

    Full Text Available Design optimization of a gas turbine blade geometry for effective film cooling toreduce the blade temperature has been done using a multiobjective optimization formulation. Three optimization formulations have been used. In the first, the average blade temperature is chosen as the objective function to be minimized. An upper bound constraint has been imposed on the maximum blade temperature. In the second, the maximum blade temperature is chosen as the objective function to be minimized with an upper bound constraint on the average blade temperature. In the third formulation, the blade average and maximum temperatures are chosen as objective functions. Shape optimization is performed using geometric parameters associated with film cooling and blade external shape. A quasi-three-dimensional Navier–Stokes solver for turbomachinery flows is used to solve for the flow field external to the blade with appropriate modifications to incorporate the effect of film cooling. The heat transfer analysis for temperature distribution within the blade is performed by solving the heat diffusion equation using the finite element method. The multiobjective Kreisselmeier–Steinhauser function approach has been used in conjunction with an approximate analysis technique for optimization. The results obtained using both formulations are compared with reference geometry. All three formulations yield significant reductions in blade temperature with the multiobjective formulation yielding largest reduction in blade temperature.

  20. Experimental and computational studies of film cooling with compound angle injection

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, R.J.; Eckert, E.R.G.; Patankar, S.V. [Univ. of Minnesota, Minneapolis, MN (United States)] [and others

    1995-10-01

    The thermal efficiency of gas turbine systems depends largely on the turbine inlet temperature. Recent decades have seen a steady rise in the inlet temperature and a resulting reduction in fuel consumption. At the same time, it has been necessary to employ intensive cooling of the hot components. Among various cooling methods, film cooling has become a standard method for cooling of the turbine airfoils and combustion chamber walls. The University of Minnesota program is a combined experimental and computational study of various film-cooling configurations. Whereas a large number of parameters influence film cooling processes, this research focuses on compound angle injection through a single row and through two rows of holes. Later work will investigate the values of contoured hole designs. An appreciation of the advantages of compound angle injection has risen recently with the demand for more effective cooling and with improved understanding of the flow; this project should continue to further this understanding. Approaches being applied include: (1) a new measurement system that extends the mass/heat transfer analogy to obtain both local film cooling and local mass (heat) transfer results in a single system, (2) direct measurement of three-dimensional turbulent transport in a highly-disturbed flow, (3) the use of compound angle and shaped holes to optimize film cooling performance, and (4) an exploration of anisotropy corrections to turbulence modeling of film cooling jets.

  1. Influence of different means of turbine blade cooling on the thermodynamic performance of combined cycle

    International Nuclear Information System (INIS)

    Sanjay; Singh, Onkar; Prasad, B.N.

    2008-01-01

    A comparative study of the influence of different means of turbine blade cooling on the thermodynamic performance of combined cycle power plant is presented. Seven schemes involving air and steam as coolants under open and closed loop cooling techniques have been studied. The open loop incorporates the internal convection, film and transpiration cooling techniques. Closed loop cooling includes only internal convection cooling. It has been found that closed loop steam cooling offers more specific work and consequently gives higher value of plant efficiency of about 60%, whereas open loop transpiration steam cooling, open loop steam internal convection cooling, transpiration air cooling, film steam cooling, film air, and internal convection air cooling have been found to yield lower values of plant efficiency in decreasing order as compared to closed loop steam cooling

  2. Investigation of the cooling film distribution in liquid rocket engine

    Directory of Open Access Journals (Sweden)

    Luís Antonio Silva

    2011-05-01

    Full Text Available This study presents the results of the investigation of a cooling method widely used in the combustion chambers, which is called cooling film, and it is applied to a liquid rocket engine that uses as propellants liquid oxygen and kerosene. Starting from an engine cooling, whose film is formed through the fuel spray guns positioned on the periphery of the injection system, the film was experimentally examined, it is formed by liquid that seeped through the inner wall of the combustion chamber. The parameter used for validation and refinement of the theoretical penetration of the film was cooling, as this parameter is of paramount importance to obtain an efficient thermal protection inside the combustion chamber. Cold tests confirmed a penetrating cold enough cooling of the film for the length of the combustion chamber of the studied engine.

  3. Film Cooling Optimization Using Numerical Computation of the Compressible Viscous Flow Equations and Simplex Algorithm

    Directory of Open Access Journals (Sweden)

    Ahmed M. Elsayed

    2013-01-01

    Full Text Available Film cooling is vital to gas turbine blades to protect them from high temperatures and hence high thermal stresses. In the current work, optimization of film cooling parameters on a flat plate is investigated numerically. The effect of film cooling parameters such as inlet velocity direction, lateral and forward diffusion angles, blowing ratio, and streamwise angle on the cooling effectiveness is studied, and optimum cooling parameters are selected. The numerical simulation of the coolant flow through flat plate hole system is carried out using the “CFDRC package” coupled with the optimization algorithm “simplex” to maximize overall film cooling effectiveness. Unstructured finite volume technique is used to solve the steady, three-dimensional and compressible Navier-Stokes equations. The results are compared with the published numerical and experimental data of a cylindrically round-simple hole, and the results show good agreement. In addition, the results indicate that the average overall film cooling effectiveness is enhanced by decreasing the streamwise angle for high blowing ratio and by increasing the lateral and forward diffusion angles. Optimum geometry of the cooling hole on a flat plate is determined. In addition, numerical simulations of film cooling on actual turbine blade are performed using the flat plate optimal hole geometry.

  4. Improving Durability of Turbine Components Through Trenched Film Cooling and Contoured Endwalls

    Energy Technology Data Exchange (ETDEWEB)

    Bogard, David G. [Univ. of Texas, Austin, TX (United States); Thole, Karen A. [Pennsylvania State Univ., State College, PA (United States)

    2014-09-30

    The experimental and computational studies of the turbine endwall and vane models completed in this research program have provided a comprehensive understanding of turbine cooling with combined film cooling and TBC. To correctly simulate the cooling effects of TBC requires the use of matched Biot number models, a technique developed in our laboratories. This technique allows for the measurement of the overall cooling effectiveness which is a measure of the combined internal and external cooling for a turbine component. The overall cooling effectiveness provides an indication of the actual metal temperature that would occur at engine conditions, and is hence a more powerful performance indicator than the film effectiveness parameter that is commonly used for film cooling studies. Furthermore these studies include the effects of contaminant depositions which are expected to occur when gas turbines are operated with syngas fuels. Results from the endwall studies performed at Penn State University and the vane model studies performed at the University of Texas are the first direct measurements of the combined effects of film cooling and TBC. These results show that TBC has a dominating effect on the overall cooling effectiveness, which enhances the importance of the internal cooling mechanisms, and downplays the importance of the film cooling of the external surface. The TBC was found to increase overall cooling effectiveness by a factor of two to four. When combined with TBC, the primary cooling from film cooling holes was found to be due to the convective cooling within the holes, not from the film effectiveness on the surface of the TBC. Simulations of the deposition of contaminants on the endwall and vane surfaces showed that these depositions caused a large increase in surface roughness and significant degradation of film effectiveness. However, despite these negative factors, the depositions caused only a slight decrease in the overall cooling effectiveness on

  5. Large Eddy Simulation of Film-Cooling Jets

    Science.gov (United States)

    Iourokina, Ioulia

    2005-11-01

    Large Eddy Simulation of inclined jets issuing into a turbulent boundary layer crossflow has been performed. The simulation models film-cooling experiments of Pietrzyk et al. (J. of. Turb., 1989), consisting of a large plenum feeding an array of jets inclined at 35° to the flat surface with a pitch 3D and L/D=3.5. The blowing ratio is 0.5 with unity density ratio. The numerical method used is a hybrid combining external compressible solver with a low-Mach number code for the plenum and film holes. Vorticity dynamics pertinent to jet-in-crossflow interactions is analyzed and three-dimensional vortical structures are revealed. Turbulence statistics are compared to the experimental data. The turbulence production due to shearing in the crossflow is compared to that within the jet hole. The influence of three-dimensional coherent structures on the wall heat transfer is investigated and strategies to increase film- cooling performance are discussed.

  6. Large Eddy simulation of flat plate film cooling at high blowing ratio using open FOAM

    Science.gov (United States)

    Baagherzadeh Hushmandi, Narmin

    2018-06-01

    In this work, numerical analysis was performed to predict the behaviour of high Reynolds number turbulent cross-flows used in film cooling applications. The geometry included one row of three discrete coolant holes inclined at 30 degrees to the main flow. In the computational model, the width of the channel was cut into one sixth and symmetry boundaries were applied in the centreline of the coolant hole and along the line of symmetry between two adjacent holes. One of the main factors that affect the performance of film cooling is the blowing ratio of coolant to the main flow. A blowing ratio equal to two was chosen in this study. Analysis showed that the common practice CFD models that employ RANS equations together with turbulence modelling under predict the film cooling effectiveness up to a factor of four. However, LES method showed better agreement of film cooling effectiveness both in tendency and absolute values compared with experimental results.

  7. Mathematical model and calculation of water-cooling efficiency in a film-filled cooling tower

    Science.gov (United States)

    Laptev, A. G.; Lapteva, E. A.

    2016-10-01

    Different approaches to simulation of momentum, mass, and energy transfer in packed beds are considered. The mathematical model of heat and mass transfer in a wetted packed bed for turbulent gas flow and laminar wave counter flow of the fluid film in sprinkler units of a water-cooling tower is presented. The packed bed is represented as the set of equivalent channels with correction to twisting. The idea put forward by P. Kapitsa on representation of waves on the interphase film surface as elements of the surface roughness in interaction with the gas flow is used. The temperature and moisture content profiles are found from the solution of differential equations of heat and mass transfer written for the equivalent channel with the volume heat and mass source. The equations for calculation of the average coefficients of heat emission and mass exchange in regular and irregular beds with different contact elements, as well as the expression for calculation of the average turbulent exchange coefficient are presented. The given formulas determine these coefficients for the known hydraulic resistance of the packed bed element. The results of solution of the system of equations are presented, and the water temperature profiles are shown for different sprinkler units in industrial water-cooling towers. The comparison with experimental data on thermal efficiency of the cooling tower is made; this allows one to determine the temperature of the cooled water at the output. The technical solutions on increasing the cooling tower performance by equalization of the air velocity profile at the input and creation of an additional phase contact region using irregular elements "Inzhekhim" are considered.

  8. Analysis of film cooling in rocket nozzles

    Science.gov (United States)

    Woodbury, Keith A.

    1992-01-01

    Computational Fluid Dynamics (CFD) programs are customarily used to compute details of a flow field, such as velocity fields or species concentrations. Generally they are not used to determine the resulting conditions at a solid boundary such as wall shear stress or heat flux. However, determination of this information should be within the capability of a CFD code, as the code supposedly contains appropriate models for these wall conditions. Before such predictions from CFD analyses can be accepted, the credibility of the CFD codes upon which they are based must be established. This report details the progress made in constructing a CFD model to predict the heat transfer to the wall in a film cooled rocket nozzle. Specifically, the objective of this work is to use the NASA code FDNS to predict the heat transfer which will occur during the upcoming hot-firing of the Pratt & Whitney 40K subscale nozzle (1Q93). Toward this end, an M = 3 wall jet is considered, and the resulting heat transfer to the wall is computed. The values are compared against experimental data available in Reference 1. Also, FDNS's ability to compute heat flux in a reacting flow will be determined by comparing the code's predictions against calorimeter data from the hot firing of a 40K combustor. The process of modeling the flow of combusting gases through the Pratt & Whitney 40K subscale combustor and nozzle is outlined. What follows in this report is a brief description of the FDNS code, with special emphasis on how it handles solid wall boundary conditions. The test cases and some FDNS solution are presented next, along with comparison to experimental data. The process of modeling the flow through a chamber and a nozzle using the FDNS code will also be outlined.

  9. Effect of an upstream bulge configuration on film cooling with and without mist injection.

    Science.gov (United States)

    Wang, Jin; Li, Qianqian; Sundén, Bengt; Ma, Ting; Cui, Pei

    2017-12-01

    To meet the economic requirements of power output, the increased inlet temperature of modern gas turbines is above the melting point of the material. Therefore, high-efficient cooling technology is needed to protect the blades from the hot mainstream. In this study, film cooling was investigated in a simplified channel. A bulge located upstream of the film hole was numerically investigated by analysis of the film cooling effectiveness distribution downstream of the wall. The flow distribution in the plate channel is first presented. Comparing with a case without bulge, different cases with bulge heights of 0.1d, 0.3d and 0.5d were examined with blowing ratios of 0.5 and 1.0. Cases with 1% mist injection were also included in order to obtain better cooling performance. Results show that the bulge configuration located upstream the film hole makes the cooling film more uniform, and enhanceslateral cooling effectiveness. Unlike other cases, the configuration with a 0.3d-height bulge shows a good balance in improving the downstream and lateral cooling effectiveness. Compared with the case without mist at M = 0.5, the 0.3d-height bulge with 1% mist injection increases lateral average effectiveness by 559% at x/d = 55. In addition, a reduction of the thermal stress concentration can be obtained by increasing the height of the bulge configuration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Technical manual for calculating cooling pond performance

    International Nuclear Information System (INIS)

    Krstulovich, S.F.

    1988-01-01

    This manual is produced in response to a growing number of requests for a technical aid to explain methods for simulating cooling pond performance. As such, it is a compilation of reports, charts and graphs developed through the years for use in analyzing situations. Section II contains a report summarizing the factors affecting cooling pond performance and lists statistical parameters used in developing performance simulations. Section III contains the graphs of simulated cooling pond performance on an hourly basis for various combinations of criteria (wind, solar, depth, air temperature and humidity) developed from the report in Section II. Section IV contains correspondence describing how to develop further data from the graphs in Section III, as well as mathematical models for the system of performance calculation. Section V contains the formulas used to simulate cooling pond performances in a cascade arrangement, such as the Fermilab Main Ring ponds. Section VI contains the calculations currently in use to evaluate the Main Ring pond performance based on current flows and Watts loadings. Section VII contains the overall site drawing of the Main Ring cooling ponds with thermal analysis and physical data

  11. A Three-Dimensional Coupled Internal/External Simulation of a Film-Cooled Turbine Vane

    Science.gov (United States)

    Heidmann, James D.; Rigby, David L.; Ameri, Ali A.

    1999-01-01

    A three-dimensional Navier-Stokes simulation has been performed for a realistic film-cooled turbine vane using the LeRC-HT code. The simulation includes the flow regions inside the coolant plena and film cooling holes in addition to the external flow. The vane is the subject of an upcoming NASA Glenn Research Center experiment and has both circular cross-section and shaped film cooling holes. This complex geometry is modeled using a multi-block grid which accurately discretizes the actual vane geometry including shaped holes. The simulation matches operating conditions for the planned experiment and assumes periodicity in the spanwise direction on the scale of one pitch of the film cooling hole pattern. Two computations were performed for different isothermal wall temperatures, allowing independent determination of heat transfer coefficients and film effectiveness values. The results indicate separate localized regions of high heat transfer coefficient values, while the shaped holes provide a reduction in heat flux through both parameters. Hole exit data indicate rather simple skewed profiles for the round holes, but complex profiles for the shaped holes with mass fluxes skewed strongly toward their leading edges.

  12. Conjugate calculation of a film-cooled blade for improvement of the leading edge cooling configuration

    Directory of Open Access Journals (Sweden)

    Norbert Moritz

    2013-03-01

    Full Text Available Great efforts are still put into the design process of advanced film-cooling configurations. In particular, the vanes and blades of turbine front stages have to be cooled extensively for a safe operation. The conjugate calculation technique is used for the three-dimensional thermal load prediction of a film-cooled test blade of a modern gas turbine. Thus, it becomes possible to take into account the interaction of internal flows, external flow, and heat transfer without the prescription of heat transfer coefficients. The focus of the investigation is laid on the leading edge part of the blade. The numerical model consists of all internal flow passages and cooling hole rows at the leading edge. Furthermore, the radial gap flow is also part of the model. The comparison with thermal pyrometer measurements shows that with respect to regions with high thermal load a qualitatively and quantitatively good agreement of the conjugate results and the measurements can be found. In particular, the region in the vicinity of the mid-span section is exposed to a higher thermal load, which requires further improvement of the cooling arrangement. Altogether the achieved results demonstrate that the conjugate calculation technique is applicable for reasonable prediction of three-dimensional thermal load of complex cooling configurations for blades.

  13. Numerical Analysis of Film Cooling at High Blowing Ratio

    Science.gov (United States)

    El-Gabry, Lamyaa; Heidmann, James; Ameri, Ali

    2009-01-01

    Computational Fluid Dynamics is used in the analysis of a film cooling jet in crossflow. Predictions of film effectiveness are compared with experimental results for a circular jet at blowing ratios ranging from 0.5 to 2.0. Film effectiveness is a surface quantity which alone is insufficient in understanding the source and finding a remedy for shortcomings of the numerical model. Therefore, in addition, comparisons are made to flow field measurements of temperature along the jet centerline. These comparisons show that the CFD model is accurately predicting the extent and trajectory of the film cooling jet; however, there is a lack of agreement in the near-wall region downstream of the film hole. The effects of main stream turbulence conditions, boundary layer thickness, turbulence modeling, and numerical artificial dissipation are evaluated and found to have an insufficient impact in the wake region of separated films (i.e. cannot account for the discrepancy between measured and predicted centerline fluid temperatures). Analyses of low and moderate blowing ratio cases are carried out and results are in good agreement with data.

  14. Optimized thin film coatings for passive radiative cooling applications

    Science.gov (United States)

    Naghshine, Babak B.; Saboonchi, Ahmad

    2018-03-01

    Passive radiative cooling is a very interesting method, which lays on low atmospheric downward radiation within 8-13 μm waveband at dry climates. Various thin film multilayer structures have been investigated in numerous experimental studies, in order to find better coatings to exploit the full potential of this method. However, theoretical works are handful and limited. In this paper, the Simulated Annealing and Genetic Algorithm are used to optimize a thin film multilayer structure for passive radiative cooling applications. Spectral radiative properties are calculated through the matrix formulation. Considering a wide range of materials, 30 high-potential convective shields are suggested. According to the calculations, cooling can be possible even under direct sunlight, using the introduced shields. Moreover, a few water-soluble materials are studied for the first time and the results show that, a KBr substrate coated by a thin CaF2 or polyethylene film can is very close to an ideal coating for passive radiative cooling at night.

  15. Modification and application of water film model in COCOSYS for PWR's passive containment cooling

    International Nuclear Information System (INIS)

    Huang, Xi; Cheng, Xu

    2014-01-01

    Highlights: • Water film model in COCOSYS has been modified by considering film breakup. • Shear stress on film surface created by countercurrent flow has been considered. • Formation and development of rivulets have been taken into account. • Modified model has been applied for passive containment cooling system. • The modified water film model has optimized the simulation results. - Abstract: In this paper the physical model describing water film behaviors in German containment code system COCOSYS has been modified by taking into consideration the film breakup and subsequent phenomena as well as the effect of film interfacial shear stress created by countercurrent air flow. The modified model has extended its capability to predict particular water film behaviors including breakup at a critical film thickness based on minimum total energy criterion, the formation of rivulets according to total energy equilibrium as well as subsequent performance of rivulets according to several assumptions and observations from experiments. Furthermore, the modification considers also the change of velocity distribution on the cross section of film/rivulets due to shear stress. Based on the geometry of AP1000 and Generic Containment, simulations predicting containment pressure variation during accidents with operation of passive containment cooling system have been carried out. With the new model, considerably larger peak pressures are observed by comparing with those predicted with original water film model within a certain range of water film flow rate. Sensitivity analyses also point out that contact angle between water rivulets and steel substrate plays a significant role in the film cooling

  16. Analysis of Turbine Blade Relative Cooling Flow Factor Used in the Subroutine Coolit Based on Film Cooling Correlations

    Science.gov (United States)

    Schneider, Steven J.

    2015-01-01

    Heat transfer correlations of data on flat plates are used to explore the parameters in the Coolit program used for calculating the quantity of cooling air for controlling turbine blade temperature. Correlations for both convection and film cooling are explored for their relevance to predicting blade temperature as a function of a total cooling flow which is split between external film and internal convection flows. Similar trends to those in Coolit are predicted as a function of the percent of the total cooling flow that is in the film. The exceptions are that no film or 100 percent convection is predicted to not be able to control blade temperature, while leaving less than 25 percent of the cooling flow in the convection path results in nearing a limit on convection cooling as predicted by a thermal effectiveness parameter not presently used in Coolit.

  17. Multidisciplinary design optimization of film-cooled gas turbine blades

    OpenAIRE

    Shashishekara S. Talya; J. N. Rajadas; A. Chattopadhyay

    1999-01-01

    Design optimization of a gas turbine blade geometry for effective film cooling toreduce the blade temperature has been done using a multiobjective optimization formulation. Three optimization formulations have been used. In the first, the average blade temperature is chosen as the objective function to be minimized. An upper bound constraint has been imposed on the maximum blade temperature. In the second, the maximum blade temperature is chosen as the objective function to be minimized with ...

  18. Effect of hole imperfection on adiabatic film cooling effectiveness

    International Nuclear Information System (INIS)

    Jovanovic, M.B.; Lange, H.C.; Steenhoven, A.A. van

    2008-01-01

    The influence of a discrete imperfection on film cooling is studied by means of thermochromic liquid crystals measurements of the adiabatic film cooling effectiveness. As a benchmark, the effect of a jet ejected through a perfect hole is used. The film cooling effectiveness achieved with an imperfect hole is compared to the benchmark. A half torus plays the role of the discrete imperfection. The influence of the presence of the imperfection, its position and the turbulence intensity of the free stream are analyzed. The measurement data are depicted as two-dimensional plots but also as integral values. It is found that the imperfection, placed one diameter from the hole leading edge, deteriorates the effectiveness at moderate velocity ratios. Under the same conditions, the same imperfection fixed at the hole exit improves the effectiveness. At the velocity ratio of 1.50, the exit imperfection improves the integral effectiveness relatively for more than two times. The turbulence intensity and imperfections placed deeper in the hole do not have a significant influence

  19. Aero-thermal optimization of film cooling flow parameters on the suction surface of a high pressure turbine blade

    Science.gov (United States)

    El Ayoubi, Carole; Hassan, Ibrahim; Ghaly, Wahid

    2012-11-01

    This paper aims to optimize film coolant flow parameters on the suction surface of a high-pressure gas turbine blade in order to obtain an optimum compromise between a superior cooling performance and a minimum aerodynamic penalty. An optimization algorithm coupled with three-dimensional Reynolds-averaged Navier Stokes analysis is used to determine the optimum film cooling configuration. The VKI blade with two staggered rows of axially oriented, conically flared, film cooling holes on its suction surface is considered. Two design variables are selected; the coolant to mainstream temperature ratio and total pressure ratio. The optimization objective consists of maximizing the spatially averaged film cooling effectiveness and minimizing the aerodynamic penalty produced by film cooling. The effect of varying the coolant flow parameters on the film cooling effectiveness and the aerodynamic loss is analyzed using an optimization method and three dimensional steady CFD simulations. The optimization process consists of a genetic algorithm and a response surface approximation of the artificial neural network type to provide low-fidelity predictions of the objective function. The CFD simulations are performed using the commercial software CFX. The numerical predictions of the aero-thermal performance is validated against a well-established experimental database.

  20. Mesoscale simulation of elastocaloric cooling in SMA films

    International Nuclear Information System (INIS)

    Wendler, Frank; Ossmer, Hinnerk; Chluba, Christoph; Quandt, Eckhard; Kohl, Manfred

    2017-01-01

    A model for the evolution of the mechanical and thermal properties of shape memory alloy (SMA) films during elastocaloric cycling is developed and compared with experiments. The focus is on Ti-Ni-Cu-Co films of 20 μm thickness showing ultra-low fatigue properties. The films undergo a highly localized pseudoelastic transformation under tensile load cycling featuring strain and temperature band patterns that depend on the loading conditions. The corresponding temperature change is of special interest for film-based elastocaloric cooling applications. Starting from a thermodynamics-based Gibbs free energy model comprising mechanical and chemical contributions, we include a martensite-austenite interface free energy term, for which formulations from a phase-field model are adapted. A 3D continuum mechanics description is modified to treat plane stress conditions appropriate for polycrystalline thin films. The nucleation mechanism of strain bands under dynamic loading is described by introducing a spatial random distribution of the transformation stress barriers reflecting the degree of material inhomogeneity. Heat transfer due to conduction and convection is taken into account. The simulations predict the correlated mechanical and thermal local response of the films including band formation and evolution, tilt angle as well as strain-rate dependence. Macroscopic stress-strain characteristics and thermal evolution curves well represent the experimental results.

  1. Lighting and cooling energy consumption in an open-plan office using solar film coating

    International Nuclear Information System (INIS)

    Li, Danny H.W.; Lam, Tony N.T.; Wong, S.L.; Tsang, Ernest K.W.

    2008-01-01

    In subtropical Hong Kong, solar heat gain via glazing contributes to a significant proportion of the building envelope cooling load. The principal fenestration design includes eliminating direct sunlight and reducing cooling requirements. Daylighting is an effective approach to allow a flexible building facade design strategy, and to enhance an energy-efficient and green building development. This paper studies the lighting and cooling energy performances for a fully air-conditioned open-plan office when solar control films together with daylight-linked lighting controls are being used. Measurements were undertaken at two stages including the electricity expenditures for the office using photoelectric dimming controls only (first stage) and together with the solar control film coatings on the windows (second stage). Electric lighting and cooling energy consumption, transmitted daylight illuminance and solar radiation were systematically recorded and analysed. The measured data were also used for conducting and validating the building energy simulations. The findings showed that the solar film coatings coupled with lighting dimming controls cut down 21.2% electric lighting and 6.9% cooling energy consumption for the open-plan office

  2. Analytical Modelling of the Effects of Different Gas Turbine Cooling Techniques on Engine Performance =

    Science.gov (United States)

    Uysal, Selcuk Can

    In this research, MATLAB SimulinkRTM was used to develop a cooled engine model for industrial gas turbines and aero-engines. The model consists of uncooled on-design, mean-line turbomachinery design and a cooled off-design analysis in order to evaluate the engine performance parameters by using operating conditions, polytropic efficiencies, material information and cooling system details. The cooling analysis algorithm involves a 2nd law analysis to calculate losses from the cooling technique applied. The model is used in a sensitivity analysis that evaluates the impacts of variations in metal Biot number, thermal barrier coating Biot number, film cooling effectiveness, internal cooling effectiveness and maximum allowable blade temperature on main engine performance parameters of aero and industrial gas turbine engines. The model is subsequently used to analyze the relative performance impact of employing Anti-Vortex Film Cooling holes (AVH) by means of data obtained for these holes by Detached Eddy Simulation-CFD Techniques that are valid for engine-like turbulence intensity conditions. Cooled blade configurations with AVH and other different external cooling techniques were used in a performance comparison study. (Abstract shortened by ProQuest.).

  3. Experimental assessment of an absorption cooling system utilizing a falling film absorber and generator

    International Nuclear Information System (INIS)

    Domínguez-Inzunza, L.A.; Hernández-Magallanes, J.A.; Soto, P.; Jiménez, C.; Gutiérrez-Urueta, G.; Rivera, W.

    2016-01-01

    Highlights: • A new prototype of an absorption cooling system using NH_3/LiNO_3 was developed. • Falling films shell and tubes heat exchangers were used as absorber and generator. • Evaporator temperatures as low as 4 °C were achieved. • The COP varied between 0.27 and 0.62 depending on the system temperatures. • A flow recirculation in the absorber was implemented showing an increase in COP. - Abstract: This study presents the results of the evaluation of an ammonia/lithium nitrate absorption cooling system. The generator and the absorber are shell and tubes falling film heat exchangers while the rest of the components are compact plate heat exchangers. A parametric study was carried out in order to determine the coefficients of performance and cooling capacities at different operating conditions. Also, an analysis was carried out to determine the influence of the absorber solution recirculation on the system performance. The generator temperatures varied between 80 °C and 100 °C, while the cooling water temperatures varied from 20 °C to 34 °C. Cooling capacities up to 4.5 kW and evaporator temperatures as low as 4 °C were achieved with the system. The internal coefficients of performance varied between 0.3 and 0.62 depending on the system operating temperatures. The system also showed good stability and repeatability.

  4. A Numerical Analysis of Heat Transfer and Effectiveness on Film Cooled Turbine Blade Tip Models

    Science.gov (United States)

    Ameri, A. A.; Rigby, D. L.

    1999-01-01

    A computational study has been performed to predict the distribution of convective heat transfer coefficient on a simulated blade tip with cooling holes. The purpose of the examination was to assess the ability of a three-dimensional Reynolds-averaged Navier-Stokes solver to predict the rate of tip heat transfer and the distribution of cooling effectiveness. To this end, the simulation of tip clearance flow with blowing of Kim and Metzger was used. The agreement of the computed effectiveness with the data was quite good. The agreement with the heat transfer coefficient was not as good but improved away from the cooling holes. Numerical flow visualization showed that the uniformity of wetting of the surface by the film cooling jet is helped by the reverse flow due to edge separation of the main flow.

  5. Validation of Heat Transfer and Film Cooling Capabilities of the 3-D RANS Code TURBO

    Science.gov (United States)

    Shyam, Vikram; Ameri, Ali; Chen, Jen-Ping

    2010-01-01

    The capabilities of the 3-D unsteady RANS code TURBO have been extended to include heat transfer and film cooling applications. The results of simulations performed with the modified code are compared to experiment and to theory, where applicable. Wilcox s k-turbulence model has been implemented to close the RANS equations. Two simulations are conducted: (1) flow over a flat plate and (2) flow over an adiabatic flat plate cooled by one hole inclined at 35 to the free stream. For (1) agreement with theory is found to be excellent for heat transfer, represented by local Nusselt number, and quite good for momentum, as represented by the local skin friction coefficient. This report compares the local skin friction coefficients and Nusselt numbers on a flat plate obtained using Wilcox's k-model with the theory of Blasius. The study looks at laminar and turbulent flows over an adiabatic flat plate and over an isothermal flat plate for two different wall temperatures. It is shown that TURBO is able to accurately predict heat transfer on a flat plate. For (2) TURBO shows good qualitative agreement with film cooling experiments performed on a flat plate with one cooling hole. Quantitatively, film effectiveness is under predicted downstream of the hole.

  6. Radiotherapy film densitometry using a slow-scan, cooled, digital CCD imaging system

    International Nuclear Information System (INIS)

    Burch, S.E.

    1993-01-01

    A method of performing high-resolution two-dimensional film densitometry for full size radiographic film (35 x 43 cm) using a cooled CCD camera was proposed. Studies were performed to evaluate the physical characteristics of the camera system and recommendations were made to assure maximum accuracy of density measurement. Test films of various sizes and densities, as well as clinical dosimetry films, were measured with the CCD densitometer and the reference transmission densitometer. The measured densities agreed within the stated accuracy of the transmission densitometer for all films with maximum density less than or equal to 1.5 optical density units. The 0.2 mm spatial resolution with 4096 shades of gray made it possible to study dose distributions even for films containing areas of high dose gradients. Patient verification radiographs were used to study exit beam dose distributions to detect errors in beam placement, patient position, and proper placement of beam modifying devices such as wedges and compensators. For studying photon beam dose distributions within phantoms, a method was developed using lead foils placed lateral to the film plane to filter very low energy scattered photons. The error in measurement of central axis percentage depth dose from film for 4 MV x-rays, 25 x 25 cm field was decreased from 65% to 4%. The method requires only two calibration films for density to dose conversion and represents an important advance in the field of film densitometry for radiotherapy. The technique was applied to the study of dynamic wedge dose distribution from a 6 MV linear accelerator. The phantom modification decreased the error in percentage depth dose from 21% to 1% for the 15 x 15 cm beam with 60 degree wedge angle. Profile off-axis errors for the same beam were decreased from 8% to 3%. The film dosimetry system provides fast, high resolution film density data for use in radiotherapy imaging and quality assurance

  7. Theoretical analysis of the performance of different cooling strategies with the concept of cool exergy

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air for the v......The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air...... for the ventilation system being outdoor air vs. air from the crawl-space, and air-to-water heat pump vs. ground heat exchanger as cooling source) on system exergy performance were investigated. It is crucial to minimize the cooling demand because it is possible to use a wide range of heat sinks (ground, lake, sea......-water, etc.) and indoor terminal units, only with a minimized demand. The water-based floor cooling system performed better than the air-based cooling system; when an air-to-water heat pump was used as the cooling source, the required exergy input was 28% smaller for the floor cooling system. The auxiliary...

  8. Validation of Supersonic Film Cooling Modeling for Liquid Rocket Engine Applications

    Science.gov (United States)

    Morris, Christopher I.; Ruf, Joseph H.

    2010-01-01

    Topics include: upper stage engine key requirements and design drivers; Calspan "stage 1" results, He slot injection into hypersonic flow (air); test articles for shock generator diagram, slot injector details, and instrumentation positions; test conditions; modeling approach; 2-d grid used for film cooling simulations of test article; heat flux profiles from 2-d flat plate simulations (run #4); heat flux profiles from 2-d backward facing step simulations (run #43); isometric sketch of single coolant nozzle, and x-z grid of half-nozzle domain; comparison of 2-d and 3-d simulations of coolant nozzles (run #45); flowfield properties along coolant nozzle centerline (run #45); comparison of 3-d CFD nozzle flow calculations with experimental data; nozzle exit plane reduced to linear profile for use in 2-d film-cooling simulations (run #45); synthetic Schlieren image of coolant injection region (run #45); axial velocity profiles from 2-d film-cooling simulation (run #45); coolant mass fraction profiles from 2-d film-cooling simulation (run #45); heat flux profiles from 2-d film cooling simulations (run #45); heat flux profiles from 2-d film cooling simulations (runs #47, #45, and #47); 3-d grid used for film cooling simulations of test article; heat flux contours from 3-d film-cooling simulation (run #45); and heat flux profiles from 3-d and 2-d film cooling simulations (runs #44, #46, and #47).

  9. Numerical study of wave disturbance in liquid cooling film

    Directory of Open Access Journals (Sweden)

    S.R. Shine

    2013-06-01

    Full Text Available Transient numerical simulations are carried out to investigate the liquid-gas interface characteristics associated with liquid film cooling flows. A two-dimensional axisymmetric multi-phase numerical model using finite volume formulation is developed. The model has been validated against available experimental data for liquid-film cooling flows inside tubes. The model has been used to predict the interface characteristics for a variety of imposed parameters and momentum flux ratios under cold flow conditions wherein both the coolant and mainstream are maintained at the same temperature. Disturbance waves are observed at the liquid-gas interface for coolant flows above a critical value and after a finite distance from the inlet. The distance toward the wave inception point increased with the increase of momentum flux ratio. However, at higher momentum flux ratios, the properties of the disturbance waves did not vary significantly. The parameters related to the liquid-gas interface waves, namely, wave velocity, frequency, amplitude and wave length have been analyzed in detail. Analysis indicates that the liquid entrainment is due to the shearing of the disturbance wave crest.

  10. Numerical analysis of hypersonic turbulent film cooling flows

    Science.gov (United States)

    Chen, Y. S.; Chen, C. P.; Wei, H.

    1992-01-01

    As a building block, numerical capabilities for predicting heat flux and turbulent flowfields of hypersonic vehicles require extensive model validations. Computational procedures for calculating turbulent flows and heat fluxes for supersonic film cooling with parallel slot injections are described in this study. Two injectant mass flow rates with matched and unmatched pressure conditions using the database of Holden et al. (1990) are considered. To avoid uncertainties associated with the boundary conditions in testing turbulence models, detailed three-dimensional flowfields of the injection nozzle were calculated. Two computational fluid dynamics codes, GASP and FDNS, with the algebraic Baldwin-Lomax and k-epsilon models with compressibility corrections were used. It was found that the B-L model which resolves near-wall viscous sublayer is very sensitive to the inlet boundary conditions at the nozzle exit face. The k-epsilon models with improved wall functions are less sensitive to the inlet boundary conditions. The testings show that compressibility corrections are necessary for the k-epsilon model to realistically predict the heat fluxes of the hypersonic film cooling problems.

  11. Effect of cross-flow direction of coolant on film cooling effectiveness with one inlet and double outlet hole injection

    Directory of Open Access Journals (Sweden)

    Guangchao Li

    2012-12-01

    Full Text Available In order to study the effect of cross-flow directions of an internal coolant on film cooling performance, the discharge coefficients and film cooling effectiveness with one inlet and double outlet hole injections were simulated. The numerical results show that two different cross-flow directions of the coolant cause the same decrease in the discharge coefficients as that in the case of supplying coolant by a plenum. The different proportion of the mass flow out of the two outlets of the film hole results in different values of the film cooling effectiveness for three different cases of coolant supplies. The film cooling effectiveness is the highest for the case of supplying coolant by the plenum. At a lower blowing ratio of 1.0, the film cooling effectiveness with coolant injection from the right entrance of the passage is higher than that from the left entrance of the passage. At a higher blowing ratio of 2.0, the opposite result is found.

  12. 2D and 3D Modeling Efforts in Fuel Film Cooling of Liquid Rocket Engines (Conference Paper with Briefing Charts)

    Science.gov (United States)

    2017-01-12

    to determine what parameters drive unsteadiness in fuel films, and how these parameters affect wall temperature profiles. Parametric studies performed...temperature profiles. Parametric studies performed in 2D suggest that a Helmholtz resonator exists for simple slot geometries. Frequencies in 3D were...effect on film cooling effectiveness. In general, the heat flux exhibits complex trends and did not scale well with chamber pressure. ∗Aerospace

  13. Thermodynamic assessment of impact of inlet air cooling techniques on gas turbine and combined cycle performance

    International Nuclear Information System (INIS)

    Mohapatra, Alok Ku; Sanjay

    2014-01-01

    The article is focused on the comparison of impact of two different methods of inlet air cooling (vapor compression and vapor absorption cooling) integrated to a cooled gas turbine based combined cycle plant. Air-film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor pressure ratio, compressor inlet temperature (T i , C ), turbine inlet temperature (T i , T ), ambient relative humidity and ambient temperature on performance parameters of plant has been carried out. Optimum T i , T corresponding to maximum plant efficiency of combined cycle increases by 100 °C due to the integration of inlet air cooling. It has been observed that vapor compression cooling improves the efficiency of gas turbine cycle by 4.88% and work output by 14.77%. In case of vapor absorption cooling an improvement of 17.2% in gas cycle work output and 9.47% in gas cycle efficiency has been observed. For combined cycle configuration, however, vapor compression cooling should be preferred over absorption cooling in terms of higher plant performance. The optimum value of compressor inlet temperature has been observed to be 20 °C for the chosen set of conditions for both the inlet air cooling schemes. - Highlights: • Inlet air cooling improves performance of cooled gas turbine based combined cycle. • Vapor compression inlet air cooling is superior to vapor absorption inlet cooling. • For every turbine inlet temperature, there exists an optimum pressure ratio. • The optimum compressor inlet temperature is found to be 293 K

  14. Experimental convective heat transfer characterization of pulsating jet in cross flow: influence of Strouhal number excitation on film cooling effectiveness

    International Nuclear Information System (INIS)

    Lalizel, Gildas; Sultan, Qaiser; Fénot, Matthieu; Dorignac, Eva

    2012-01-01

    In actual gas turbine system, unsteadiness of the mainstream flow influences heat transfer and surface pressure distribution on the blade. In order to simulate these conditions, an experimental film cooling study with externally imposed pulsation is performed with purpose of characterizing both effects of turbine unsteadiness on film cooling (with frequency ranges typical to actual turbine), and also to figure out the range of Strouhal number pulsation under various blowing conditions, which could possibly deliver a performance improvement in film cooling. Influence of injection flow pulsation on adiabatic effectiveness and convective heat transfer coefficient are determined from IR-thermography of the wall for distances to the hole exit between 0 and 30 D.

  15. Performing coolness: smoking refusal and adolescent identities.

    Science.gov (United States)

    Plumridge, E W; Fitzgerald, L J; Abel, G M

    2002-04-01

    The implications of smoking refusal for personal identity style were studied through conversations in six small focus groups or dyads of 13- and 14-year-old non-smokers from an urban New Zealand secondary school. The approach to analyzing their talk was informed by notions of 'performativity' and 'social space' to focus on the connections between identity and social relations. Smoking emerged as a key signifier of power and status. It was salient at both top and bottom ends of the social hierarchy depending upon the competence displayed in smoking as part of a larger ensemble of personal deportment and behavior. Being a non-smoker therefore inevitably carried connotations of being 'average' or 'in the middle', presenting non-smoking adolescents with the problem of accrediting themselves against superior 'smoker cool' groups. A discourse analytic approach was used to examine the resources and strategies participants brought to bear on this 'problem', which was then seen to be solved differently by boys and girls. Boys could establish alternatives to 'smoker cool' through physical activity, girls had little recourse but to accept their inferior status. The implications of this for health education and promotion are discussed.

  16. Mechanism of Film Cooling with One Inlet and Double Outlet Hole Injection at Various Turbulence Intensities

    Science.gov (United States)

    Li, Guangchao; Chen, Yukai; Kou, Zhihai; Zhang, Wei; Zhang, Guochen

    2018-03-01

    The trunk-branch hole was designed as a novel film cooling concept, which aims for improving film cooling performance by producing anti-vortex. The trunk-branch hole is easily manufactured in comparison with the expanded hole since it consists of two cylindrical holes. The effect of turbulence on the film cooling effectiveness with a trunk-branch hole injection was investigated at the blowing ratios of 0.5, 1.0, 1.5 and 2.0 by numerical simulation. The turbulence intensities from 0.4 % to 20 % were considered. The realizable graphic id="j_tjj-2016-0024_ingr_001" xlink.href="graphic/j_tjj-2016-0024_inline1.png" />k-ɛ k - ɛ turbulence model and the enhanced wall function were used. The more effective anti-vortex occurs at the low blowing ratio of 0.5 %. The high turbulence intensity causes the effectiveness evenly distributed in the spanwise direction. The increase of turbulence intensity leads to a slight decrease of the spanwise averaged effectiveness at the low blowing ratio of 0.5, but a significant increase at the high blowing ratios of 1.5 and 2.0. The optimal blowing ratio of the averaged surface effectiveness is improved from 1.0 to 1.5 when the turbulence intensity increases from 0.4 % to 20 %.

  17. Study of Cooling Characteristic of The Containment APWR Model Using Laminar Subcooled Water Film

    International Nuclear Information System (INIS)

    Diah Hidayanti; Aryadi Suwono; Nathanael P Tandian; Ari Darmawan Pasek; Efrizon Umar

    2009-01-01

    One of mechanism utilized by the next-generation pressurized water reactor for cooling its containment passively is gravitationally falling water spray cooling. This paper focuses on the characteristic study using Fluent 5/6 program for the case of the containment outer wall cooling by laminar sub-cooled water film. The cooling system characteristics which will be discussed consist of water film thickness and temperature on all parts of the containment wall as well as the effect of water spray volume flow rate on the water film thickness and convection heat transfer capability from the containment wall to the film bulk. In addition, some kinds of non dimensional numbers involved in the film heat transfer correlation will be presented in this paper. (author)

  18. Cooling Performance of ALIP according to the Air or Sodium Cooling Type

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Huee-Youl; Yoon, Jung; Lee, Tae-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    ALIP pumps the liquid sodium by Lorentz force produced by the interaction of induced current in the liquid metal and their associated magnetic field. Even though the efficiency of the ALIP is very low compared to conventional mechanical pumps, it is very useful due to the absence of moving parts, low noise and vibration level, simplicity of flow rate regulation and maintenance, and high temperature operation capability. Problems in utilization of ALIP concern a countermeasure for elevation of internal temperature of the coil due to joule heating and how to increase magnetic flux density of Na channel gap. The conventional ALIP usually used cooling methods by circulating the air or water. On the other hand, GE-Toshiba developed a double stator pump adopting the sodium-immersed self-cooled type, and it recovered the heat loss in sodium. Therefore, the station load factor of the plant could be reduced. In this study, the cooling performance with cooling types of ALIP is analyzed. We developed thermal analysis models to evaluate the cooling performance of air or sodium cooling type of ALIP. The cooling performance is analyzed for operating parameters and evaluated with cooling type. 1-D and 3-D thermal analysis model for IHTS ALIP was developed, and the cooling performance was analyzed for air or sodium cooling type. The cooling performance for air cooling type was better than sodium cooling type at higher air velocity than 0.2 m/s. Also, the air temperature of below 270 .deg. demonstrated the better cooling performance as compared to sodium.

  19. Experimental study of film media used for evaporative pre-cooling of air

    International Nuclear Information System (INIS)

    He, Suoying; Guan, Zhiqiang; Gurgenci, Hal; Hooman, Kamel; Lu, Yuanshen; Alkhedhair, Abdullah M.

    2014-01-01

    Highlights: • Two film media were experimentally studied in a low-speed wind tunnel. • Correlations for heat transfer coefficient and pressure drop were developed. • Cellulose media provide higher cooling efficiency and pressure drop than PVC media. • Water entrainment of PVC media happens even at relatively low air velocities. - Abstract: An open-circuit low-speed wind tunnel was used to study the performance of evaporative cooling with cellulose and Polyvinyl Chloride (PVC) corrugated media. These two film media were selected as part of a broader investigation on pre-cooling the entering air of natural draft dry cooling towers. The heat and mass transfer and pressure drop across the two media with three thicknesses (i.e., 100, 200 and 300 mm) were experimentally studied in the wind tunnel. The test data were non-dimensionalized and curve fitted to yield a set of correlations. It was found that the pressure drop range of the cellulose media is 1.5–101.7 Pa while the pressure drops of the PVC media are much lower with the range of 0.9–49.2 Pa, depending on the medium thickness, air velocity and water flow rate. The cooling efficiencies of the cellulose media vary from 43% to 90% while the cooling efficiencies of the PVC media are 8% to 65%, depending on the medium thickness and air velocity. The water entrainment off the media was detected by water sensitive papers, and found that the cellulose media have negligible water entrainment under the studied conditions while care must be taken in the use of PVC media as water entrainment happens even at relatively low air velocities

  20. Film Cooled Recession of SiC/SiC Ceramic Matrix Composites: Test Development, CFD Modeling and Experimental Observations

    Science.gov (United States)

    Zhu, Dongming; Sakowski, Barbara A.; Fisher, Caleb

    2014-01-01

    SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. However, the environmental stability of Si-based ceramics in high pressure, high velocity turbine engine combustion environment is of major concern. The water vapor containing combustion gas leads to accelerated oxidation and corrosion of the SiC based ceramics due to the water vapor reactions with silica (SiO2) scales forming non-protective volatile hydroxide species, resulting in recession of the ceramic components. Although environmental barrier coatings are being developed to help protect the CMC components, there is a need to better understand the fundamental recession behavior of in more realistic cooled engine component environments.In this paper, we describe a comprehensive film cooled high pressure burner rig based testing approach, by using standardized film cooled SiCSiC disc test specimen configurations. The SiCSiC specimens were designed for implementing the burner rig testing in turbine engine relevant combustion environments, obtaining generic film cooled recession rate data under the combustion water vapor conditions, and helping developing the Computational Fluid Dynamics (CFD) film cooled models and performing model validation. Factors affecting the film cooled recession such as temperature, water vapor concentration, combustion gas velocity, and pressure are particularly investigated and modeled, and compared with impingement cooling only recession data in similar combustion flow environments. The experimental and modeling work will help predict the SiCSiC CMC recession behavior, and developing durable CMC systems in complex turbine engine operating conditions.

  1. AC-600 passive containment cooling system performance research

    International Nuclear Information System (INIS)

    Jia Baoshan; Yu Jiyang; Shi Junying

    1997-01-01

    a code named PCCSAC which is able to predict both the evaporating film on the outside surface of the vessel and the condensed film on its inside is developed successfully. It is a special software tool to analyze the passive containment cooling system (PCCS) performance in the design of AC-600. The author includes the establishment of physical models, selection of numerical methods, debugging and verification of the code and application of the code in the AC-600 PCCS. In physical models, the fundamental conservation equations about various areas and heat conduction equations are established. In order to make the equations to meet the closed form of solution, a lot of structure formulae are complemented. After repeated selection and demonstration of the numerical methods, the backward difference method Gear which is generally used for stiff problem is chosen for the solution of ordinary differential equations derived from the physical models. The results of standard example calculated by the PCCSAC code and the COMMIX code which is used to analyze westinghouse AP-600 are same in the main. The reliability and validity are verified from the calculations. The PCCSAC code is applied in the calculations of two important LOCA used in the containment safety analyses. The sensitivity of main parameters in the system based on LOCA are studied. All the results are reasonable and in agreement with the theoretical analyses. It can be concluded that the PCCSAC code is able to be used for the analyses of AC-600 PCCS performance

  2. Evaluation of heat exchange performance for the auxiliary component cooling water system cooling tower in HTTR

    International Nuclear Information System (INIS)

    Tochio, Daisuke; Kameyama, Yasuhiko; Shimizu, Atsushi; Inoi, Hiroyuki; Yamazaki, Kazunori; Shimizu, Yasunori; Aragaki, Etsushi; Ota, Yukimaru; Fujimoto, Nozomu

    2006-09-01

    The auxiliary component cooling water system (ACCWS) is one of the cooling system in High Temperature Engineering Test Reactor (HTTR). The ACCWS has main two features, many facilities cooling, and heat sink of the vessel cooling system which is one of the engineering safety features. Therefore, the ACCWS is required to satisfy the design criteria of heat removal performance. In this report, heat exchange performance data of the rise-to-power-up test and the in-service operation for the ACCWS cooling tower was evaluated. Moreover, the evaluated values were compared with the design values, and it is confirmed that ACCWS cooling tower has the required heat exchange performance in the design. (author)

  3. Performance characteristics of a shower cooling tower

    International Nuclear Information System (INIS)

    Qi Xiaoni; Liu Zhenyan; Li Dandan

    2007-01-01

    This study was prompted by the need to design towers for applications in which, due to salt deposition on the packing and subsequent blockage, the use of tower packing is not practical. In contrast to conventional cooling towers, the cooling tower analyzed in this study is void of fill. By means of efficient atomization nozzles, a shower cooling tower (SCT) is possible to be applied in industry, which, in terms of water cooling, energy saving and equipment investing, is better than conventional packed cooling towers. However, no systematic thermodynamic numerical method could be found in the literature up to now. Based on the kinetic model and mass and heat transfer model, this paper has developed a one dimensional model for studying the motional process and evaporative cooling process occurring at the water droplet level in the SCT. The finite difference approach is used for three motional processes to obtain relative parameters in each different stage, and the possibility of the droplets being entrained outside the tower is fully analyzed. The accuracy of this model is checked by practical operational results from a full scale prototype in real conditions, and some exclusive factors that affect the cooling characteristics for the SCT are analyzed in detail. This study provides the theoretical foundation for practical application of the SCT in industry

  4. Development of High Performance Cooling Modules in Notebook PC's

    Science.gov (United States)

    Tanahashi, Kosei

    The CPU power consumption in Notebook PCs is increasing every year. Video chips and HDDs are also continually using larger power for higher performance. In addition, since miniaturization is desired, the mounting of components is becoming more and more dense. Accordingly, the cooling mechanisms are increasingly important. The cooling modules have to dissipate larger amounts of heat in the same environmental conditions. Therefore, high capacity cooling capabilities is needed, while low costs and high reliability must be retained. Available cooling methods include air or water cooling systems and the heat conduction method. The air cooling system is to transmit heat by a cooling fan often using a heat pipe. The water cooling one employs the water to carry heat to the back of the display, which offers a comparatively large cooling area. The heat conduction method is to transfer the heat by thermal conduction to the case. This article describes the development of new and comparatively efficient cooling devices offering low cost and high reliability for air cooling system. As one of the development techniques, the heat resistance and performance are measured for various parts and layouts. Each cooling system is evaluated in the same measurement environment. With regards to the fans, an optimal shape of the fan blades to maximize air flow is found by using CFD simulation, and prototypes were built and tested.

  5. Performance Analysis of XCPC Powered Solar Cooling Demonstration Project

    Science.gov (United States)

    Widyolar, Bennett K.

    A solar thermal cooling system using novel non-tracking External Compound Parabolic Concentrators (XCPC) has been built at the University of California, Merced and operated for two cooling seasons. Its performance in providing power for space cooling has been analyzed. This solar cooling system is comprised of 53.3 m2 of XCPC trough collectors which are used to power a 23 kW double effect (LiBr) absorption chiller. This is the first system that combines both XCPC and absorption chilling technologies. Performance of the system was measured in both sunny and cloudy conditions, with both clean and dirty collectors. It was found that these collectors are well suited at providing thermal power to drive absorption cooling systems and that both the coinciding of available thermal power with cooling demand and the simplicity of the XCPC collectors compared to other solar thermal collectors makes them a highly attractive candidate for cooling projects.

  6. Performance of cooling installation for cyclotron Decy-13

    International Nuclear Information System (INIS)

    Edi Trijono Budisantoso; Suprapto; Sutadi

    2015-01-01

    Has been calculated the cooling installation performance of Decy-13 cyclotron. The cooling installation is analysed based on the technical specifications of each cooling component to proof the results of the design and implementation of installations meet the cooling requirement. Analysis of loss of pressure and flow rate in the piping installation is done empirically using Hazen-Williams equation while the analysis of heat transfer processes in the cooling tower is done using the help of psychometric charts that available. Cooling component consists of a condenser and associated piping systems with cooling towers and equipped with a pump to push the circulation of cooling. The calculations show that the installation of the condenser cooler uses the cooling tower LiangChi LBC-30 with a booster pump Grundfos 4 kW NF30-36T powered 47kW able to transfer heat with the coolant flow rate 136 lpm, input to output coolant pressure difference 2.1atm and the cooling temperature difference 5 °C. Conclusion of the calculation is the technical specifications of cooling components and installation already meets the needs of the cooling expected. (author)

  7. Heat transfer from a plate cooled by a water film with countercurrent air flow

    International Nuclear Information System (INIS)

    Ambrosini, W.; Manfredini, A.; Mariotti, F.; Oriolo, F.; Vigni, P.

    1995-01-01

    An experimental program at the University of Pisa provides specific data for the evaluation of heat and mass transfer by falling film evaporation. The problem is addressed primarily because of its relevance to the study of the behavior of passive containment cooling systems in simplified pressurized water reactors. In these plants, after an accident that releases vapor from the primary circuit, the steel containment envelope is cooled either by an ascending stream of air in natural circulation or by the combination of air flow and falling film evaporation. To qualify models for the prediction of the heat transfer capabilities in postulated accident conditions, researchers have built an experimental facility consisting of a flat heated plate with water sprays and a fan to simulate a countercurrent air stream. The range of relevant parameters to be investigated has been determined on the basis of integral calculations performed for the AP600 reactor containment. The facility has enabled the collection of data that confirm the adequacy of the classical heat and mass transfer analogy in predicting evaporation phenomena. Further developments in the research are needed to confirm the first results and to extend the experimental database by considering more subtle aspects of the phenomenon such as the characteristics of surface waviness of the water film and its effect on heat transfer

  8. Effect of ribbed and smooth coolant cross-flow channel on film cooling

    International Nuclear Information System (INIS)

    Peng, Wei; Sun, Xiaokai; Jiang, Peixue; Wang, Jie

    2017-01-01

    Highlights: • Little different for plenum model and the cross-flow model at M = 0.5. • Crossflow model is much better than plenum model at M = 1.0, especially with ribs. • Coolant flow channel with V-shaped ribs has the best adiabatic film cooling. • Film cooling with the plenum model is better at M = 0.5 than at M = 1.0. • Crossflow model is better at M = 0.5 near film hole and at M = 1.0 for downstream. - Abstract: The influence of ribbed and unribbed coolant cross-flow channel on film cooling was investigated with the coolant supply being either a plenum-coolant feed or a coolant cross-flow feed. Validation experiments were conducted with comparison to numerical results using different RANS turbulence models showed that the RNG k–ε turbulence model and the RSM model gave closer predictions to the experimental data than the other RANS models. The results indicate that at a low blowing ratio of M = 0.5, the coolant supply channel structure has little effect on the film cooling. However, at a high blowing ratio of M = 1.0, the adiabatic wall film cooling effectiveness is significantly lower with the plenum feed than with the cross-flow feed, especially for the cases with ribs. The film cooling with the plenum model is better at M = 0.5 than at M = 1.0. The film cooling with the cross-flow model is better at a blowing ratio of M = 0.5 in the near hole region, while further downstream, it is better at M = 1.0. The results also show that the coolant cross-flow channel with V-shaped ribs has the best adiabatic film cooling effectiveness.

  9. Effect of ribbed and smooth coolant cross-flow channel on film cooling

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Wei; Sun, Xiaokai [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China); Jiang, Peixue, E-mail: jiangpx@tsinghua.edu.cn [Key Laboratory for Thermal Science and Power Engineering of Ministry of Educations, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Wang, Jie [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2017-05-15

    Highlights: • Little different for plenum model and the cross-flow model at M = 0.5. • Crossflow model is much better than plenum model at M = 1.0, especially with ribs. • Coolant flow channel with V-shaped ribs has the best adiabatic film cooling. • Film cooling with the plenum model is better at M = 0.5 than at M = 1.0. • Crossflow model is better at M = 0.5 near film hole and at M = 1.0 for downstream. - Abstract: The influence of ribbed and unribbed coolant cross-flow channel on film cooling was investigated with the coolant supply being either a plenum-coolant feed or a coolant cross-flow feed. Validation experiments were conducted with comparison to numerical results using different RANS turbulence models showed that the RNG k–ε turbulence model and the RSM model gave closer predictions to the experimental data than the other RANS models. The results indicate that at a low blowing ratio of M = 0.5, the coolant supply channel structure has little effect on the film cooling. However, at a high blowing ratio of M = 1.0, the adiabatic wall film cooling effectiveness is significantly lower with the plenum feed than with the cross-flow feed, especially for the cases with ribs. The film cooling with the plenum model is better at M = 0.5 than at M = 1.0. The film cooling with the cross-flow model is better at a blowing ratio of M = 0.5 in the near hole region, while further downstream, it is better at M = 1.0. The results also show that the coolant cross-flow channel with V-shaped ribs has the best adiabatic film cooling effectiveness.

  10. Shape-optimization of round-to-slot holes for improving film cooling effectiveness on a flat surface

    Science.gov (United States)

    Huang, Ying; Zhang, Jing-zhou; Wang, Chun-hua

    2018-06-01

    Single-objective optimization for improving adiabatic film cooling effectiveness is performed for single row of round-to-slot film cooling holes on a flat surface by using CFD analysis and surrogate approximation methods. Among the main geometric parameters, dimensionless hole-to-hole pitch ( P/ d) and slot length-to-diameter ( l/ d) are fixed as 2.4 and 2 respectively, and the other parameters (hole height-to-diameter ratio, slot width-to-diameter and inclination angle) are chosen as the design variables. Given a wide range of possible geometric variables, the geometric optimization of round-to-slot holes is carried out under two typical blowing ratios of M = 0.5 and M = 1.5 by selecting a spatially-averaged adiabatic film cooling effectiveness between x/ d = 2 and x/ d = 12 as the objective function to be maximized. Radial basis function neural network is applied for constructing the surrogate model and then the optimal design point is searched by a genetic algorithm. It is revealed that the optimal round-to-slot hole is of converging feature under a low blowing ratio but of diffusing feature under a high blowing ratio. Further, the influence principle of optimal round-to-slot geometry on film cooling performance is illustrated according to the detailed flow and thermal behaviors.

  11. Suction Side Roughness Effects on Film Cooling Heat Transfer on a Turbine Vane

    National Research Council Canada - National Science Library

    Rutledge, James

    2004-01-01

    An experimental study was conducted in a simulated three vane linear cascade to determine the effects of surface roughness and film cooling on the heat transfer coefficient distribution in the region...

  12. Active Control of Transverse Jets for Film Cooling Applications: A Limited Statement of Work

    National Research Council Canada - National Science Library

    Nikitopoulos, D. E

    2006-01-01

    .... A theoretical analysis was conducted and mechanisms that can play a defining role in film cooling control were identified on the basis of fundamental fluid-dynamics, prior experiments and preliminary...

  13. Cooling Performance Analysis of ThePrimary Cooling System ReactorTRIGA-2000Bandung

    Science.gov (United States)

    Irianto, I. D.; Dibyo, S.; Bakhri, S.; Sunaryo, G. R.

    2018-02-01

    The conversion of reactor fuel type will affect the heat transfer process resulting from the reactor core to the cooling system. This conversion resulted in changes to the cooling system performance and parameters of operation and design of key components of the reactor coolant system, especially the primary cooling system. The calculation of the operating parameters of the primary cooling system of the reactor TRIGA 2000 Bandung is done using ChemCad Package 6.1.4. The calculation of the operating parameters of the cooling system is based on mass and energy balance in each coolant flow path and unit components. Output calculation is the temperature, pressure and flow rate of the coolant used in the cooling process. The results of a simulation of the performance of the primary cooling system indicate that if the primary cooling system operates with a single pump or coolant mass flow rate of 60 kg/s, it will obtain the reactor inlet and outlet temperature respectively 32.2 °C and 40.2 °C. But if it operates with two pumps with a capacity of 75% or coolant mass flow rate of 90 kg/s, the obtained reactor inlet, and outlet temperature respectively 32.9 °C and 38.2 °C. Both models are qualified as a primary coolant for the primary coolant temperature is still below the permitted limit is 49.0 °C.

  14. The effects of radiant cooling versus convective cooling on human eye tear film stability and blinking rate

    DEFF Research Database (Denmark)

    Nygaard, Linette; Uth, Simon C.; Bolashikov, Zhecho Dimitrov

    2014-01-01

    The effect of indoor temperature, radiant and convective cooling on tear film stability and eye blink frequency was examined. 24 human subjects were exposed to the non-uniform environment generated by localised chilled beam and a chilled ceiling combined with overhead mixing ventilation. The subj......The effect of indoor temperature, radiant and convective cooling on tear film stability and eye blink frequency was examined. 24 human subjects were exposed to the non-uniform environment generated by localised chilled beam and a chilled ceiling combined with overhead mixing ventilation....... The subjects participated in four two-hour experiments. The room air temperature was kept at 26 °C or 28 °C. Tear film samples were collected after 30 min of acclimatisation and at the end of the exposures. Eye blinking frequency was analysed for the first and last 15 min of each exposure. The tear film...... stability decreased as the temperature increased. The highest number of subjects with unchanged or improved tear film quality was observed with the localised chilled beam at 26 °C. A trend was found between subjects who reported eye irritation and had a bad tear film quality....

  15. Performance evaluation on cool roofs for green remodeling

    Science.gov (United States)

    Yun, Yosun; Cho, Dongwoo; Cho, Kyungjoo

    2018-06-01

    Cool roofs refer that maximize heat emission, and minimize the absorption of solar radiation energy, by applying high solar reflectance paints, or materials to roofs or rooftops. The application of cool roofs to existing buildings does not need to take structural issues into consideration, as rooftop greening, is an alternative that can be applied to existing buildings easily. This study installed a cool roofs on existing buildings, and evaluated the performances, using the results to propose certification standards for green remodeling, considering the cool roof-related standards.

  16. Dry cooling with night cool storage to enhance solar power plants performance in extreme conditions areas

    International Nuclear Information System (INIS)

    Muñoz, J.; Martínez-Val, J.M.; Abbas, R.; Abánades, A.

    2012-01-01

    Highlights: ► Solar thermo-electric power plants with thermal storage for condenser cooling. ► Technology to mitigate the negative effect on Rankine cycles of the day-time high temperatures in deserts. ► Electricity production augmentation in demand-peak hours by the use of day-night temperature difference. -- Abstract: Solar thermal power plants are usually installed in locations with high yearly average solar radiation, often deserts. In such conditions, cooling water required for thermodynamic cycles is rarely available. Moreover, when solar radiation is high, ambient temperature is very high as well; this leads to excessive condensation temperature, especially when air-condensers are used, and decreases the plant efficiency. However, temperature variation in deserts is often very high, which drives to relatively low temperatures during the night. This fact can be exploited with the use of a closed cooling system, so that the coolant (water) is chilled during the night and store. Chilled water is then used during peak temperature hours to cool the condenser (dry cooling), thus enhancing power output and efficiency. The present work analyzes the performance improvement achieved by night thermal cool storage, compared to its equivalent air cooled power plant. Dry cooling is proved to be energy-effective for moderately high day–night temperature differences (20 °C), often found in desert locations. The storage volume requirement for different power plant efficiencies has also been studied, resulting on an asymptotic tendency.

  17. Thermal performance of cooling system for a laptop computer using a boiling enhancement microstructure

    International Nuclear Information System (INIS)

    Cho, N. H.; Jeong, W. Y.; Park, S. H.

    2008-01-01

    The increasing heat generation rates in CPU of notebook computers motivate a research on cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase cooling system using a micropump to circulate a dielectric liquid(PF5060). The cooling system consists of an evaporator containing a boiling enhancement microstructure connected to a condenser with mini fans providing external forced convection. The cooling system is characterized by a parametric study which determines the effects of volume fill ratio of coolant, existence of a boiling enhancement microstructure and pump flow rates on thermal performance of the closed loop. Experimental data shows the optimal parametric values which can dissipate 33.9W with a film heater maintained at 95 .deg. C

  18. Thermal performance of cooling system for a laptop computer using a boiling enhancement microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Cho, N. H.; Jeong, W. Y.; Park, S. H. [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2008-07-01

    The increasing heat generation rates in CPU of notebook computers motivate a research on cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase cooling system using a micropump to circulate a dielectric liquid(PF5060). The cooling system consists of an evaporator containing a boiling enhancement microstructure connected to a condenser with mini fans providing external forced convection. The cooling system is characterized by a parametric study which determines the effects of volume fill ratio of coolant, existence of a boiling enhancement microstructure and pump flow rates on thermal performance of the closed loop. Experimental data shows the optimal parametric values which can dissipate 33.9W with a film heater maintained at 95 .deg. C.

  19. Contrastive analysis of cooling performance between a high-level water collecting cooling tower and a typical cooling tower

    Science.gov (United States)

    Wang, Miao; Wang, Jin; Wang, Jiajin; Shi, Cheng

    2018-02-01

    A three-dimensional (3D) numerical model is established and validated for cooling performance optimization between a high-level water collecting natural draft wet cooling tower (HNDWCT) and a usual natural draft wet cooling tower (UNDWCT) under the actual operation condition at Wanzhou power plant, Chongqing, China. User defined functions (UDFs) of source terms are composed and loaded into the spray, fill and rain zones. Considering the conditions of impact on three kinds of corrugated fills (Double-oblique wave, Two-way wave and S wave) and four kinds of fill height (1.25 m, 1.5 m, 1.75 m and 2 m), numerical simulation of cooling performance are analysed. The results demonstrate that the S wave has the highest cooling efficiency in three fills for both towers, indicating that fill characteristics are crucial to cooling performance. Moreover, the cooling performance of the HNDWCT is far superior to that of the UNDWCT with fill height increases of 1.75 m and above, because the air mass flow rate in the fill zone of the HNDWCT improves more than that in the UNDWCT, as a result of the rain zone resistance declining sharply for the HNDWCT. In addition, the mass and heat transfer capacity of the HNDWCT is better in the tower centre zone than in the outer zone near the tower wall under a uniform fill layout. This behaviour is inverted for the UNDWCT, perhaps because the high-level collection devices play the role of flow guiding in the inner zone. Therefore, when non-uniform fill layout optimization is applied to the HNDWCT, the inner zone increases in height from 1.75 m to 2 m, the outer zone reduces in height from 1.75 m to 1.5 m, and the outlet water temperature declines approximately 0.4 K compared to that of the uniform layout.

  20. Cooling performance of a notebook PC mounted with heat spreader

    Energy Technology Data Exchange (ETDEWEB)

    Noh, H.K. [Electronics and Telecommunications Research Institute, Taejeon (Korea); Lim, K.B. [Hanbat National University, Taejeon (Korea); Park, M.H. [Korea Power Engineering Company (Korea)

    2001-06-01

    Parametric study to investigate the cooling performance of a notebook PC mounted with heat spreader has been numerically performed. Two case of air-blowing and air-exhaust at inlet were tested. The cooling effect on parameters such as, inlet velocities in the cases of air-blowing and air-exhaust, materials of heat spreader, and CPU powers were simulated for two cases. Cooling performance in the case of air-blowing was better than the case of air-exhaust. (author). 9 refs., 7 figs., 5 tabs.

  1. Fabrication of Thermoelectric Sensor and Cooling Devices Based on Elaborated Bismuth-Telluride Alloy Thin Films

    Directory of Open Access Journals (Sweden)

    Abdellah Boulouz

    2014-01-01

    Full Text Available The principal motivation of this work is the development and realization of smart cooling and sensors devices based on the elaborated and characterized semiconducting thermoelectric thin film materials. For the first time, the details design of our sensor and the principal results are published. Fabrication and characterization of Bi/Sb/Te (BST semiconducting thin films have been successfully investigated. The best values of Seebeck coefficient (α(T at room temperature for Bi2Te3, and (Bi1−xSbx2Te3 with x = 0.77 are found to be −220 µV/K and +240 µV/K, respectively. Fabrication and evaluation of performance devices are reported. 2.60°C of cooling of only one Peltier module device for an optimal current of Iopt=2.50 mA is obtained. The values of temperature measured by infrared camera, by simulation, and those measured by the integrated and external thermocouple are reported. A sensitivity of the sensors of 5 mV Torr−1 mW−1 for the pressure sensor has been found with a response time of about 600 ms.

  2. Measurements of 3D velocity and scalar field for a film-cooled airfoil trailing edge

    Energy Technology Data Exchange (ETDEWEB)

    Benson, Michael J.; Elkins, Christopher J.; Eaton, John K. [Stanford University, Department of Mechanical Engineering, Stanford, CA (United States)

    2011-08-15

    The 3D velocity and concentration fields have been measured for flow in a pressure side cutback trailing edge film cooling geometry consisting of rectangular film cooling slots separated by tapered lands. The velocity field was measured using conventional magnetic resonance velocimetry, and the concentration distribution was measured with a refined magnetic resonance concentration technique that yields experimental uncertainties for the concentration between 5 and 6%. All experiments were performed in water. A separation bubble behind the slot lip entrains coolant and promotes rapid turbulent mixing at the upper edge of the coolant jet. Vortices from inside the slot feed channel and on the upper sides of the lands rapidly distort the initially rectangular shape of the coolant stream and sweep mainstream flow toward the airfoil surface. The vortices also prevent any coolant from reaching the upper surfaces of the land. At the trailing edge, a second separation region exists in the blunt trailing edge wake. The flow forms suction side streaks behind the land tips, as well as streaks behind the slot centers on the pressure side. The peak coolant concentrations in the streaks remain above 25% through the end of the measurement domain, over 30 slot heights downstream. (orig.)

  3. The development of evaporative liquid film model for analysis of passive containment cooling system

    International Nuclear Information System (INIS)

    Park, Hong June; Hwang, Young Dong; Kim, Hee Cheol; Kim, Young In; Chang, Moon Hee

    2000-07-01

    An analytical model was developed to simulate behavior of the liquid film formed on the outside surface of the steel containment vessel of PCCS including the ellipsoidal dome and the vertical wall. The model was coupled with CFX code using the user subroutines provided by the code, and a series of numerical calculations were performed to evaluate the evaporative heat transfer coefficient at the interface. Numerical results for Sherwood number and evaporative heat transfer coefficient were compared with the experimental data. The results were in good agreement with the experimental data. The calculated liquid film thickness showed good agreement with that of Sun except an upper portion of the channel. The model was applied to the full scale of PCCS to investigate the effects of dome and chimney on the evaporation rate. The results showed that the heat transfer coefficient in the dome region, where the flow cross-sectional area decreases and the swirling occurs, was lower than that of the vertical annulus region. The calculated evaporative heat transfer coefficient was about 20 times larger than that of the dry cooling. Sensitivity studies on the gap size and the wall temperature were also performed to figure out their effects on the heat transfer coefficient and inlet air average velocity. Through the analysis of the dryout point, the minimum liquid film flow rate to cover the entire surface of the vessel was estimated

  4. The development of evaporative liquid film model for analysis of passive containment cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hong June; Hwang, Young Dong; Kim, Hee Cheol; Kim, Young In; Chang, Moon Hee

    2000-07-01

    An analytical model was developed to simulate behavior of the liquid film formed on the outside surface of the steel containment vessel of PCCS including the ellipsoidal dome and the vertical wall. The model was coupled with CFX code using the user subroutines provided by the code, and a series of numerical calculations were performed to evaluate the evaporative heat transfer coefficient at the interface. Numerical results for Sherwood number and evaporative heat transfer coefficient were compared with the experimental data. The results were in good agreement with the experimental data. The calculated liquid film thickness showed good agreement with that of Sun except an upper portion of the channel. The model was applied to the full scale of PCCS to investigate the effects of dome and chimney on the evaporation rate. The results showed that the heat transfer coefficient in the dome region, where the flow cross-sectional area decreases and the swirling occurs, was lower than that of the vertical annulus region. The calculated evaporative heat transfer coefficient was about 20 times larger than that of the dry cooling. Sensitivity studies on the gap size and the wall temperature were also performed to figure out their effects on the heat transfer coefficient and inlet air average velocity. Through the analysis of the dryout point, the minimum liquid film flow rate to cover the entire surface of the vessel was estimated.

  5. Performance improvement of air-cooled refrigeration system by using evaporatively cooled air condenser

    Energy Technology Data Exchange (ETDEWEB)

    Hajidavalloo, E.; Eghtedari, H. [Mechanical Engineering Department, Shahid Chamran University, Golestan St., Ahvaz (Iran)

    2010-08-15

    Increasing the coefficient of performance of air conditioner with air-cooled condenser is a challenging problem especially in area with very hot weather conditions. Application of evaporatively cooled air condenser instead of air-cooled condenser is proposed in this paper as an efficient way to solve the problem. An evaporative cooler was built and coupled to the existing air-cooled condenser of a split-air-conditioner in order to measure its effect on the cycle performance under various ambient air temperatures up to 49 C. Experimental results show that application of evaporatively cooled air condenser has significant effect on the performance improvement of the cycle and the rate of improvement is increased as ambient air temperature increases. It is also found that by using evaporatively cooled air condenser in hot weather conditions, the power consumption can be reduced up to 20% and the coefficient of performance can be improved around 50%. More improvements can be expected if a more efficient evaporative cooler is used. (author)

  6. Nonlinear Analysis of Actuation Performance of Shape Memory Alloy Composite Film Based on Silicon Substrate

    Directory of Open Access Journals (Sweden)

    Shuangshuang Sun

    2014-01-01

    Full Text Available The mechanical model of the shape memory alloy (SMA composite film with silicon (Si substrate was established by the method of mechanics of composite materials. The coupled action between the SMA film and Si substrate under thermal loads was analyzed by combining static equilibrium equations, geometric equations, and physical equations. The material nonlinearity of SMA and the geometric nonlinearity of bending deformation were both considered. By simulating and analyzing the actuation performance of the SMA composite film during one cooling-heating thermal cycle, it is found that the final cooling temperature, boundary condition, and the thickness of SMA film have significant effects on the actuation performance of the SMA composite film. Besides, the maximum deflection of the SMA composite film is affected obviously by the geometric nonlinearity of bending deformation when the thickness of SMA film is very large.

  7. Cooling performance of helium-gas/water coolers in HENDEL

    International Nuclear Information System (INIS)

    Inagaki, Yoshiyuki; Takada, Shoji; Hayashi, Haruyoshi; Kobayashi, Toshiaki; Ohta, Yukimaru; Shimomura, Hiroaki; Miyamoto, Yoshiaki

    1994-01-01

    The helium engineering demonstration loop (HENDEL) has four helium-gas/water coolers where the cooling water flows in the tubes and helium gas on the shell side. Their cooling performance was studied using the operational data from 1982 to 1991. The heat transfer of helium gas on the shell was obtained for segmental and step-up baffle type coolers. Also, the change with operation time was investigated. The cooling performance was lowered by the graphite powder released from the graphite components for several thousand hours and thereafter recovered because the graphite powder from the components was reduced and the powder in the cooler shell was blown off during the operation. (orig.)

  8. Improving performance and reducing costs of cooling towers

    International Nuclear Information System (INIS)

    Bartz, J.A.

    1992-01-01

    Cooling towers represent a significant capital investment at a steam electric power station. In addition, deficiencies in thermal performance can result in major operating penalties of fuel cost, replacement energy, and capacity addition. This paper summarizes two recent EPRI research projects aimed at reducing thermal performance deficiencies and decreasing installed costs of evaporative cooling towers. First, EPRI Research Project 2113, Cooling Tower Performance Prediction and Improvement, is summarized. This project has resulted in published data sets on the measured thermal performance characteristics of a variety of cooling tower packings, computer codes to predict tower performance, and computer code validation through large-scale tower performance measurements. Principal results are contained in an EPRIGEMS software module, Cooling Tower Advisor. This PC- based software contains a tutorial plus codes to predict tower thermal performance, arranged in a user-friendly format. The second EPRI effort, Research Project 2819-10/11, Fabric Structures for Power Plant Applications, has resulted in designs and costs of large structures with shells constructed of recently-developed fabrics. Primary power plant applications for such structures are the shells of natural draft cooling towers and coal-pile covers. Fabric structures offer low initial cost, acceptable life, and seismic superiority, among other advantages. Detailed conceptual designs and installed cost data are reviewed. 8 refs., 9 figs., 3 tabs

  9. Peltier cooling and onsager reciprocity in ferromagnetic thin films.

    Science.gov (United States)

    Avery, A D; Zink, B L

    2013-09-20

    We present direct measurements of the Peltier effect as a function of temperature from 77 to 325 K in Ni, Ni(80)Fe(20), and Fe thin films made using a suspended Si-N membrane structure. Measurement of the Seebeck effect in the same films allows us to directly test predictions of Onsager reciprocity between the Peltier and Seebeck effects. The Peltier coefficient Π is negative for both Ni and Ni(80)Fe(20) films and positive for the Fe film. The Fe film also exhibits a peak associated with the magnon drag Peltier effect. The observation of magnon drag in the Fe film verifies that the coupling between the phonon, magnon, and electron systems in the film is the same whether driven by heat current or charge current. The excellent agreement between Π values predicted using the experimentally determined Seebeck coefficient for these films and measured values offers direct experimental confirmation of the Onsager reciprocity between these thermoelectric effects in ferromagnetic thin films near room temperature.

  10. Influence of Stern Shaft Inclination on the Cooling Performance of Water-Lubricated Bearing

    Directory of Open Access Journals (Sweden)

    Zou Li

    2016-01-01

    Full Text Available The water film model of the marine water-lubricated stern bearing was established by FLUENT. The influence law of water flow rate on the cooling performance of water-lubricated bearing was studied in consideration of the stern shaft inclination. It will be helpful to improve the performance of marine water-lubricated stern bearing and both security and reliability of propulsion system. The simulation results show that the increase of cooling water flow rate in a certain range can effectively reduce bearing temperature. The bearing temperature rises sharply with thinning of water film thickness which is caused by the increase of inclination angle. Larger inclination angle can deteriorate the operating reliability of bearing.

  11. A Numerical Study of Anti-Vortex Film Cooling Designs at High Blowing Ratio

    Science.gov (United States)

    Heidmann, James D.

    2008-01-01

    A concept for mitigating the adverse effects of jet vorticity and liftoff at high blowing ratios for turbine film cooling flows has been developed and studied at NASA Glenn Research Center. This "anti-vortex" film cooling concept proposes the addition of two branched holes from each primary hole in order to produce a vorticity counter to the detrimental kidney vortices from the main jet. These vortices typically entrain hot freestream gas and are associated with jet separation from the turbine blade surface. The anti-vortex design is unique in that it requires only easily machinable round holes, unlike shaped film cooling holes and other advanced concepts. The anti-vortex film cooling hole concept has been modeled computationally for a single row of 30deg angled holes on a flat surface using the 3D Navier-Stokes solver Glenn-HT. A modification of the anti-vortex concept whereby the branched holes exit adjacent to the main hole has been studied computationally for blowing ratios of 1.0 and 2.0 and at density ratios of 1.0 and 2.0. This modified concept was selected because it has shown the most promise in recent experimental studies. The computational results show that the modified design improves the film cooling effectiveness relative to the round hole baseline and previous anti-vortex cases, in confirmation of the experimental studies.

  12. Transient Three-Dimensional Side Load Analysis of a Film Cooled Nozzle

    Science.gov (United States)

    Wang, Ten-See; Guidos, Mike

    2008-01-01

    Transient three-dimensional numerical investigations on the side load physics for an engine encompassing a film cooled nozzle extension and a regeneratively cooled thrust chamber, were performed. The objectives of this study are to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet history based on an engine system simulation. Ultimately, the computational results will be provided to the nozzle designers for estimating of effect of the peak side load on the nozzle structure. Computations simulating engine startup at ambient pressures corresponding to sea level and three high altitudes were performed. In addition, computations for both engine startup and shutdown transients were also performed for a stub nozzle, operating at sea level. For engine with the full nozzle extension, computational result shows starting up at sea level, the peak side load occurs when the lambda shock steps into the turbine exhaust flow, while the side load caused by the transition from free-shock separation to restricted-shock separation comes at second; and the side loads decreasing rapidly and progressively as the ambient pressure decreases. For the stub nozzle operating at sea level, the computed side loads during both startup and shutdown becomes very small due to the much reduced flow area.

  13. Optimization of cooling tower performance analysis using Taguchi method

    Directory of Open Access Journals (Sweden)

    Ramkumar Ramakrishnan

    2013-01-01

    Full Text Available This study discuss the application of Taguchi method in assessing maximum cooling tower effectiveness for the counter flow cooling tower using expanded wire mesh packing. The experiments were planned based on Taguchi’s L27 orthogonal array .The trail was performed under different inlet conditions of flow rate of water, air and water temperature. Signal-to-noise ratio (S/N analysis, analysis of variance (ANOVA and regression were carried out in order to determine the effects of process parameters on cooling tower effectiveness and to identity optimal factor settings. Finally confirmation tests verified this reliability of Taguchi method for optimization of counter flow cooling tower performance with sufficient accuracy.

  14. PERFORMANCE EVALUATION OF CEILING RADIANT COOLING SYSTEM IN COMPOSITE CLIMATE

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anuj [Malaviya National Institute of Technology (MNIT), Jaipur, India; Mathur, Jyotirmay [Malaviya National Institute of Technology (MNIT), Jaipur, India; Bhandari, Mahabir S [ORNL

    2015-01-01

    Radiant cooling systems are proving to be an energy efficient solution due to higher thermal capacity of cooling fluid especially for the buildings that require individual zone controls and where the latent loads are moderate. The Conventional air conditioners work at very low temperature i.e.5-8 c (refrigerant evaporator inlet) while the radiant cooling systems, also referred as high temperature cooling system, work at high temperatures i.e. 14-18 c. The radiant cooling systems can maintain lower MRT (Mean Radiant Temperature) as ceiling panels maintain uniform temperature gradient inside room and provide higher human comfort. The radiant cooling systems are relatively new systems and their operation and energy savings potential are not quantified for a large number of buildings and operational parameters. Moreover, there are only limited numbers of whole building simulation studies have been carried out for these systems to have a full confidence in the capability of modelling tools to simulate these systems and predict the impact of various operating parameters. Theoretically, savings achieve due to higher temperature set point of chilled water, which reduces chiller-running time. However, conventional air conditioner runs continuously to maintain requisite temperature. In this paper, experimental study for performance evaluation of radiant cooling system carried out on system installed at Malaviya National Institute of Technology Jaipur. This paper quantifies the energy savings opportunities and effective temperature by radiant cooling system at different chilled water flow rates and temperature range. The data collected/ analysed through experimental study will used for calibration and validation of system model of building prepared in building performance simulation software. This validated model used for exploring optimized combinations of key parameters for composite climate. These optimized combinations will used in formulation of radiant cooling system

  15. Cooling improves the writing performance of patients with writer's cramp.

    Science.gov (United States)

    Pohl, Christoph; Happe, Jörg; Klockgether, Thomas

    2002-11-01

    Cooling of hand and forearm muscles by immersion in 15 degrees C cold water for 5 minutes improved the writing performance of patients with writer's cramp. Since abnormal processing of muscle spindle afferent discharges contributes to the pathology of writer's cramp, this effect might result from a reduction in muscle spindle activity by lowering muscle temperature. Cooling is a simple, cheap, and safe procedure, providing temporary relief for patients with writer's cramp. Copyright 2002 Movement Disorder Society

  16. Optimization of cooling tower performance analysis using Taguchi method

    OpenAIRE

    Ramkumar Ramakrishnan; Ragupathy Arumugam

    2013-01-01

    This study discuss the application of Taguchi method in assessing maximum cooling tower effectiveness for the counter flow cooling tower using expanded wire mesh packing. The experiments were planned based on Taguchi’s L27 orthogonal array .The trail was performed under different inlet conditions of flow rate of water, air and water temperature. Signal-to-noise ratio (S/N) analysis, analysis of variance (ANOVA) and regression were carried out in order to determine the effects of process...

  17. An Experimental and Numerical Investigation of Endwall Aerodynamics and Heat Transfer in a Gas Turbine Nozzle Guide Vane with Slot Film Cooling

    Science.gov (United States)

    Alqefl, Mahmood Hasan

    In many regions of the high-pressure gas turbine, film cooling flows are used to protect the turbine components from the combustor exit hot gases. Endwalls are challenging to cool because of the complex system of secondary flows that disturb surface film coolant coverage. The secondary flow vortices wash the film coolant from the surface into the mainstream significantly decreasing cooling effectiveness. In addition to being effected by secondary flow structures, film cooling flow can also affect these structures by virtue of their momentum exchange. In addition, many studies in the literature have shown that endwall contouring affects the strength of passage secondary flows. Therefore, to develop better endwall cooling schemes, a good understanding of passage aerodynamics and heat transfer as affected by interactions of film cooling flows with secondary flows is required. This experimental and computational study presents results from a linear, stationary, two-passage cascade representing the first stage nozzle guide vane of a high-pressure gas turbine with an axisymmetrically contoured endwall. The sources of film cooling flows are upstream combustor liner coolant and endwall slot film coolant injected immediately upstream of the cascade passage inlet. The operating conditions simulate combustor exit flow features, with a high Reynolds number of 390,000 and approach flow turbulence intensity of 11% with an integral length scale of 21% of the chord length. Measurements are performed with varying slot film cooling mass flow to mainstream flow rate ratios (MFR). Aerodynamic effects are documented with five-hole probe measurements at the exit plane. Heat transfer is documented through recovery temperature measurements with a thermocouple. General secondary flow features are observed. Total pressure loss measurements show that varying the slot film cooling MFR has some effects on passage loss. Velocity vectors and vorticity distributions show a very thin, yet intense

  18. Performance limit of daytime radiative cooling in warm humid environment

    Directory of Open Access Journals (Sweden)

    Takahiro Suichi

    2018-05-01

    Full Text Available Daytime radiative cooling potentially offers efficient passive cooling, but the performance is naturally limited by the environment, such as the ambient temperature and humidity. Here, we investigate the performance limit of daytime radiative cooling under warm and humid conditions in Okayama, Japan. A cooling device, consisting of alternating layers of SiO2 and poly(methyl methacrylate on an Al mirror, is fabricated and characterized to demonstrate a high reflectance for sunlight and a selective thermal radiation in the mid-infrared region. In the temperature measurement under the sunlight irradiation, the device shows 3.4 °C cooler than a bare Al mirror, but 2.8 °C warmer than the ambient of 35 °C. The corresponding numerical analyses reveal that the atmospheric window in λ = 16 ∼ 25 μm is closed due to a high humidity, thereby limiting the net emission power of the device. Our study on the humidity influence on the cooling performance provides a general guide line of how one can achieve practical passive cooling in a warm humid environment.

  19. Improvement of Cooling Performance of a Compact Thermoelectric Air Conditioner Using a Direct Evaporative Cooling System

    Science.gov (United States)

    Tipsaenporm, W.; Lertsatitthanakorn, C.; Bubphachot, B.; Rungsiyopas, M.; Soponronnarit, S.

    2012-06-01

    This paper presents the results of tests carried out to investigate the potential application of a direct evaporative cooling (DEC) system for improving the performance of a compact thermoelectric (TE) air conditioner. The compact TE air conditioner is composed of three TE modules. The cold and hot sides of the TE modules were fixed to rectangular fin heat sinks. The DEC system produced cooling air that was used to assist the release of heat from the heat sinks at the hot side of the TE modules. The results showed that the cooling air dry bulb temperature from the DEC system achieved drops of about 5.9°C in parallel with about a 33.4% rise in relative humidity. The cooling efficiency of the DEC system varies between 72.1% and 81.5%. It increases the cooling capacity of the compact TE air conditioner from 53.0 W to 74.5 W. The 21.5 W (40.6%) increase represents the difference between the compact air conditioner operating with ambient air flowing through the TE module's heat sinks, and the compact air conditioner operating with the cooler air from the DEC system flowing through the TE module's heat sinks. In both scenarios, electric current of 4.5 A was supplied to the TE modules. It also has been experimentally proven that the coefficient of performance (COP) of the compact TE air conditioner can be improved by up to 20.9% by incorporating the DEC system.

  20. Performance comparison between a solar driven rotary desiccant cooling system and conventional vapor compression system (performance study of desiccant cooling)

    International Nuclear Information System (INIS)

    Ge, T.S.; Ziegler, F.; Wang, R.Z.; Wang, H.

    2010-01-01

    Solar driven rotary desiccant cooling systems have been widely recognized as alternatives to conventional vapor compression systems for their merits of energy-saving and being eco-friendly. In the previous paper, the basic performance features of desiccant wheel have been discussed. In this paper, a solar driven two-stage rotary desiccant cooling system and a vapor compression system are simulated to provide cooling for one floor in a commercial office building in two cities with different climates: Berlin and Shanghai. The model developed in the previous paper is adopted to predict the performance of the desiccant wheel. The objectives of this paper are to evaluate and compare the thermodynamic and economic performance of the two systems and to obtain useful data for practical application. Results show that the desiccant cooling system is able to meet the cooling demand and provide comfortable supply air in both of the two regions. The required regeneration temperatures are 55 deg. C in Berlin and 85 deg. C in Shanghai. As compared to the vapor compression system, the desiccant cooling system has better supply air quality and consumes less electricity. The results of the economic analysis demonstrate that the dynamic investment payback periods are 4.7 years in Berlin and 7.2 years in Shanghai.

  1. Testing Solutions for Adult Film Performers.

    Science.gov (United States)

    Bergman, Zachary R

    2014-01-01

    The majority of the nation's adult films are produced in California, and within California, most production occurs in Los Angeles. In order to regulate that content, the County of Los Angeles passed the Safer Sex in the Adult Film Industry Act (Measure B) by way of referendum in November 2012. Measure B requires that adult film producers wishing to film in Los Angeles County obtain permits from the Los Angeles County Department of Public Health, and it also mandates that adult film performers use condoms while filming and "engaging in anal or vaginal sexual intercourse." Nevertheless, between August 2013 and January 2014, several adult film performers in California tested positive for HIV, and the threat of infection remains. Although Measure B is not the best way forward for Los Angeles County, elements of the ordinance should be incorporated into future legislative efforts. Given the economic ramifications of industry flight due to more localized regulations, this Note concludes that California should pass statewide comprehensive reform. Any such new legislation must treat "independent contractors," the classification generally used for adult film performs, as if they were regular employees. Legislation should also couple mandatory testing mechanisms with provisions granting performers the right to choose whether they use condoms. Finally, legislation must include mechanisms that ensure performers' preferences are not improperly tainted by outside forces and pressures. While there will always be risks associated with the production of adult content, if undertaken, these reforms could significantly mitigate those hazards.

  2. Parametric study of closed wet cooling tower thermal performance

    Science.gov (United States)

    Qasim, S. M.; Hayder, M. J.

    2017-08-01

    The present study involves experimental and theoretical analysis to evaluate the thermal performance of modified Closed Wet Cooling Tower (CWCT). The experimental study includes: design, manufacture and testing prototype of a modified counter flow forced draft CWCT. The modification based on addition packing to the conventional CWCT. A series of experiments was carried out at different operational parameters. In view of energy analysis, the thermal performance parameters of the tower are: cooling range, tower approach, cooling capacity, thermal efficiency, heat and mass transfer coefficients. The theoretical study included develops Artificial Neural Network (ANN) models to predicting various thermal performance parameters of the tower. Utilizing experimental data for training and testing, the models simulated by multi-layer back propagation algorithm for varying all operational parameters stated in experimental test.

  3. Transient Three-Dimensional Side Load Analysis of Out-of-Round Film Cooled Nozzles

    Science.gov (United States)

    Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike

    2010-01-01

    The objective of this study is to investigate the effect of nozzle out-of-roundness on the transient startup side loads at a high altitude, with an anchored computational methodology. The out-of-roundness could be the result of asymmetric loads induced by hardware attached to the nozzle, asymmetric internal stresses induced by previous tests, and deformation, such as creep, from previous tests. The rocket engine studied encompasses a regeneratively cooled thrust chamber and a film cooled nozzle extension with film coolant distributed from a turbine exhaust manifold. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet history based on an engine system simulation. Transient startup computations were performed with the out-of-roundness achieved by four different degrees of ovalization: one perfectly round, one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation-line-jump is the peak side load physics for the round, slightly our-of-round, and more out-of-round cases, and the peak side load increases as the degree of out-of-roundness increases. For the significantly out-of-round nozzle, however, the peak side load reduces to comparable to that of the round nozzle and the separation line jump is not the peak side load physics. The counter-intuitive result of the significantly out-of-round case is found to be related to a side force reduction mechanism that splits the effect of the separation-line-jump into two parts, not only in the circumferential direction and most importantly in time.

  4. Effect of Half Time Cooling on Thermoregulatory Responses and Soccer-Specific Performance Tests

    OpenAIRE

    Yang Zhang; Svetlana Nepocatych; Charlie P. Katica; Annie B. Collins,; Catalina Casaru,; Gytis Balilionis; Jesper Sjökvist; Phillip A. Bishop

    2014-01-01

    This study examined two active coolings (forearm and hand cooling, and neck cooling) during a simulated half-time recovery on thermoregulatory responses and subsequent soccer-specific exercise performance. Following a 45-min treadmill run in the heat, participants (N=7) undertook 15-min recovery with either passive cooling, forearm and hand cooling, or neck cooling in a simulated cooled locker room environment. After the recovery, participants performed a 6×15-m sprint test and Yo-Yo Intermit...

  5. CEGB research on the effects of fouling of plastic packings on natural draught cooling tower performance

    International Nuclear Information System (INIS)

    Winter, R.J.

    1989-01-01

    Plastic film packings were first used in CEGB natural draught cooling towers in 1985. Since then, cooling towers at seven power stations have been repacked using various commercial designs of plastic packing, with generally satisfactory results in economic terms. However, fouling of all the packings has occurred to some extent, ranging from very thin films on the surface of the sheets, which actually enhances performance, to heavy and voluminous formations which severely constrict the inter-sheet passages, causing performance loss and threatening the structural integrity of the whole fill. At CERL, methods have been developed to relate the degree of fouling to the thermal performance loss. This information is enabling accurate calculations to be made of the economics of repacking. Samples of fouled packing from operation towers are tested using the Experimental Cooling Tower at the Central Electricity Research Laboratories at Leatherhead. A systematic investigation is also underway of the changes in pressure drop and mass transfer coefficients which take place as fouling develops, using progressively-fouled packing samples from a purpose-built Packing Fouling Facility located at one of the power stations. The performance data obtained is fed-back into models by which the effect of high fouling loadings on various packings is calculated, enabling packing economic life to be predicted

  6. Cooling Performance of Natural Circulation for a Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Suki; Chun, J. H.; Yum, S. B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    This paper deals with the core cooling performance by natural circulation during normal operation and a flow channel blockage event in an open tank-in-pool type research reactor. The cooling performance is predicted by using the RELAP5/ MOD3.3 code. The core decay heat is usually removed by natural circulation to the reactor pool water in open tank-in-pool type research reactors with the thermal power less than several megawatts. Therefore, these reactors have generally no active core cooling system against a loss of normal forced flow. In reactors with the thermal power less than around one megawatt, the reactor core can be cooled down by natural circulation even during normal full power operation. The cooling performance of natural circulation in an open tank-in-pool type research reactor has been investigated during the normal natural circulation and a flow channel blockage event. It is found that the maximum powers without void generation at the hot channel are around 1.16 MW and 820 kW, respectively, for the normal natural circulation and the flow channel blockage event.

  7. Reynolds-Averaged Navier-Stokes Solutions to Flat Plate Film Cooling Scenarios

    Science.gov (United States)

    Johnson, Perry L.; Shyam, Vikram; Hah, Chunill

    2011-01-01

    The predictions of several Reynolds-Averaged Navier-Stokes solutions for a baseline film cooling geometry are analyzed and compared with experimental data. The Fluent finite volume code was used to perform the computations with the realizable k-epsilon turbulence model. The film hole was angled at 35 to the crossflow with a Reynolds number of 17,400. Multiple length-to-diameter ratios (1.75 and 3.5) as well as momentum flux ratios (0.125 and 0.5) were simulated with various domains, boundary conditions, and grid refinements. The coolant to mainstream density ratio was maintained at 2.0 for all scenarios. Computational domain and boundary condition variations show the ability to reduce the computational cost as compared to previous studies. A number of grid refinement and coarsening variations are compared for further insights into the reduction of computational cost. Liberal refinement in the near hole region is valuable, especially for higher momentum jets that tend to lift-off and create a recirculating flow. A lack of proper refinement in the near hole region can severely diminish the accuracy of the solution, even in the far region. The effects of momentum ratio and hole length-to-diameter ratio are also discussed.

  8. Performance test of solar-assisted ejector cooling system

    KAUST Repository

    Huang, Bin-Juine

    2014-03-01

    A solar-assisted ejector cooling/heating system (SACH-2k) is built and test result is reported. The solar-driven ejector cooling system (ECS) is connected in series with an inverter-type air conditioner (IAC). Several advanced technologies are developed in SACH-k2, including generator liquid level control in ECS, the ECS evaporator temperature control, and optimal control of fan power in cooling tower of ECS. From the field test results, the generator liquid level control performs quite well and keeps stable performance of ejector. The ECS evaporator temperature control also performs satisfactorily to keep ejector performance normally under low or fluctuating solar radiation. The fan power control system cooling tower performs stably and reduces the power consumption dramatically without affecting the ECS performance. The test results show that the overall system COPo including power consumptions of peripheral increases from 2.94-3.3 (IAC alone) to 4.06-4.5 (SACH-k2), about 33-43%. The highest COPo is 4.5. © 2013 Elsevier Ltd and IIR. All rights reserved.

  9. Flat plate film cooling at the coolant supply into triangular and cylindrical craters

    Directory of Open Access Journals (Sweden)

    Khalatov Artem A.

    2017-01-01

    Full Text Available The results are given of the film cooling numerical simulation of three different schemes including single-array of the traditional round inclined holes, as well as inclined holes arranged in the cylindrical or triangular dimples (craters. The results of simulation showed that at the medium and high values of the blowing ratio (m > 1.0 the scheme with coolant supply into triangular craters improves the adiabatic film cooling efficiency by 1.5…2.7 times compared to the traditional array of inclined holes, or by 1.3…1.8 times compared to the scheme with coolant supply into cylindrical craters. The greater film cooling efficiency with the coolant supply into triangular craters is explained by decrease in the intensity of secondary vortex structures (“kidney” vortex. This is due to the partial destruction and transformation of the coolant jets structure interacting with front wall of the crater. Simultaneously, the film cooling uniformity is increased in the span-wise direction.

  10. Thermodynamic performance analysis of gas-fired air-cooled adiabatic absorption refrigeration systems

    International Nuclear Information System (INIS)

    Wang, L.; Chen, G.M.; Wang, Q.; Zhong, M.

    2007-01-01

    In China, the application of small size gas-fired air-cooled absorption refrigeration systems as an alternative for electric compression air conditioning systems has shown broad prospects due to occurrence of electricity peak demand in Chinese big cities and lack of water resources. However, for conventional air-cooled absorption refrigeration systems, it is difficult to enhance the heat and mass transfer process in the falling film absorber, and may cause problems, for example, remarkable increase of pressure, temperature and concentration in the generators, risk of crystallization, acceleration of corrosion, degradation of performance, and so on. This paper presents a gas-fired air-cooled adiabatic absorption refrigeration system using lithium bromide-water solutions as its working fluid, which is designed with a cooling capacity of 16 kW under standard conditions. The system has two new features of waste heat recovery of condensed water from generator and an adiabatic absorber with an air cooler. Performance simulation and characteristic analysis are crucial for the optimal control and reliability of operation in extremely hot climates. A methodology is presented to simulate thermodynamic performance of the system. The influences of outdoor air temperature on operation performances of the system are investigated

  11. Film-cooled turbine endwall in a transonic flow field; Filmgekuehlte Turbinenplattform in transsonischem Stroemungsfeld

    Energy Technology Data Exchange (ETDEWEB)

    Nicklas, M.

    2000-11-01

    Aero and thermodynamic measurements at the endwall of a turbine nozzle guide vane were carried out. These investigations are the first where the complete blade passage at the endwall in a transonic flow field is analysed for heat transfer and adiabatic film-cooling effectiveness. The aerodynamic measurements identify an intensive interaction between the coolant air and the secondary flow field. Similarly strong variations in heat transfer and film-cooling effectiveness were found. Analysis of the heat transfer measurements indicates that the heat transfer represents an indispensable tool for the evaluation of platform film-cooling design. On the basis of infrared temperature measurements, a procedure for accurate analysis of heat transfer and film-cooling effectiveness in a complex transonic flow field was developed. This measurement technique combines high accuracy with flexibility of application. These investigations have led to design improvements for film-cooling systems at the platform. (orig.) [German] Aero- und thermodynamische Messungen an einer Plattform eines Turbinenleitrads werden beschrieben. Erstmals wird in einem transsonischen Stroemungsfeld die komplette Seitenwand bezueglich des Waermeuebergangs und der adiabaten Filmkuehleffektivitaet untersucht. Die aerodynamischen Messungen zeigen eine intensive Wechselwirkung der Kuehlluft mit dem Sekundaerstroemungsfeld. Daraus resultierend treten starke Aenderungen des Waermeuebergangs und der Filmkuehleffektivitaet auf. Die Resultate der Waermeuebergangsmessungen zeigen, dass der Waermeuebergang eine wichtige Groesse fuer die Bewertung eines Filmkuehldesigns an einer Plattform darstellt. Ein Messverfahren auf der Grundlage von Infrarot-Temperaturmessungen fuer eine genaue Analyse des Waermeuebergangs und der Filmkuehleffektivitaet in den komplexen Verhaeltnissen einer transsonischen Stroemung wurde entwickelt. Mit der verwendeten Messtechnik wird eine hohe Genauigkeit bei der Ermittlung der quantitativen

  12. Performance test of solar-assisted ejector cooling system

    KAUST Repository

    Huang, Bin-Juine; Ton, Wei-Zhe; Wu, Chen-Chun; Ko, Hua-Wei; Chang, Hsien-Shun; Hsu, Hang-Yuen; Liu, Jen-Hao; Wu, Jia-Hung; Yen, Rue-Her

    2014-01-01

    are developed in SACH-k2, including generator liquid level control in ECS, the ECS evaporator temperature control, and optimal control of fan power in cooling tower of ECS. From the field test results, the generator liquid level control performs quite well

  13. Use of a laser-induced fluorescence thermal imaging system for film cooling heat transfer measurement

    Energy Technology Data Exchange (ETDEWEB)

    Chyu, M.K. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    1995-10-01

    This paper describes a novel approach based on fluorescence imaging of thermographic phosphor that enables the simultaneous determination of both local film effectiveness and local heat transfer on a film-cooled surface. The film cooling model demonstrated consists of a single row of three discrete holes on a flat plate. The transient temperature measurement relies on the temperature-sensitive fluorescent properties of europium-doped lanthanum oxysulfide (La{sub 2}O{sub 2}S:EU{sup 3+}) thermographic phosphor. A series of full-field surface temperatures, mainstream temperatures, and coolant film temperatures were acquired during the heating of a test surface. These temperatures are used to calculate the heat transfer coefficients and the film effectiveness simultaneously. Because of the superior spatial resolution capability for the heat transfer data reduced from these temperature frames, the laser-induced fluorescence (LIF) imaging system, the present study observes the detailed heat transfer characteristics over a film-protected surface. The trend of the results agrees with those obtained using other conventional thermal methods, as well as the liquid crystal imaging technique. One major advantage of this technique is the capability to record a large number of temperature frames over a given testing period. This offers multiple-sample consistency.

  14. Performance characteristics of counter flow wet cooling towers

    International Nuclear Information System (INIS)

    Khan, Jameel-Ur-Rehman; Yaqub, M.; Zubair, Syed M.

    2003-01-01

    Cooling towers are one of the biggest heat and mass transfer devices that are in widespread use. In this paper, we use a detailed model of counter flow wet cooling towers in investigating the performance characteristics. The validity of the model is checked by experimental data reported in the literature. The thermal performance of the cooling towers is clearly explained in terms of varying air and water temperatures, as well as the driving potential for convection and evaporation heat transfer, along the height of the tower. The relative contribution of each mode of heat transfer rate to the total heat transfer rate in the cooling tower is established. It is demonstrated with an example problem that the predominant mode of heat transfer is evaporation. For example, evaporation contributes about 62.5% of the total rate of heat transfer at the bottom of the tower and almost 90% at the top of the tower. The variation of air and water temperatures along the height of the tower (process line) is explained on psychometric charts

  15. Effect of shocks on film cooling of a full scale turbojet exhaust nozzle having an external expansion surface

    Science.gov (United States)

    Straight, D. M.

    1979-01-01

    Cooling is one of the critical technologies for efficient design of exhaust nozzles, especially for the developing technology of nonaxisymmetric (2D) nozzles for future aircraft applications. Several promising 2D nozzle designs have external expansion surfaces which need to be cooled. Engine data are scarce, however, on nozzle cooling effectiveness in the supersonic flow environment (with shocks) that exists along external expansion surfaces. This paper will present experimental film cooling data obtained during exploratory testing with an axisymmetric plug nozzle having external expansion and installed on an afterburning turbojet engine in an altitude test facility. The data obtained shows that the shocks and local hot gas stream conditions have a marked effect on film cooling effectiveness. An existing film cooling correlation is adequate at some operating conditions but inadequate at other conditions such as in separated flow regions resulting from shock-boundary-layer interactions.

  16. Decrement in manual arm performance during whole body cooling.

    Science.gov (United States)

    Giesbrecht, G G; Bristow, G K

    1992-12-01

    Six subjects performed three manual arm tasks: 1) prior to immersion in 8 degrees C water; 2) soon after immersion to the neck, but prior to any decrease in core temperature; and 3) every 15 min until core temperatures decreased 2-4.5 degrees C. The tasks were speed of flexion and extension of the fingers, handgrip strength and manual dexterity. There was no immediate effect of cold immersion; however, all scores decreased significantly after core temperature decreased 0.5 degrees C. Further decrease in core temperature was associated with a progressive impairment of performance, although at a slower rate than during the first 0.5 degrees C decrease. Flexion and extension of the fingers was affected relatively more than handgrip strength or manual dexterity. Decrement in performance is a result of peripheral cooling on sensorimotor function with a probable additional effect of central cooling on cerebral function.

  17. Genetic Algorithm Optimization of a Film Cooling Array on a Modern Turbine Inlet Vane

    Science.gov (United States)

    2012-09-01

    downstream. Due to the symmetric nature of the cooling design, each set of lines for a given downstream location bears the same shape. The dramatic...Chandran, P. M. D., Halder, P., Panda , R. K., and Prasad, B. V. S. S. S., “A Comparative Study of Film Cooling Effectiveness on a Flat Plate with...Adiabatic and Conjugate Conditions for Different Hole Shapes,” Proceedings of the ASME Turbo Expo 2012, paper GT2012-69142. [58] Panda , R. K. and

  18. Review of RSG-GAS secondary cooling pump performance

    International Nuclear Information System (INIS)

    Marsahala, Y.B.

    1999-01-01

    The control system of RSG-GAS secondary pump is the study for the operation existence of RSG-GAS secondary pump. The research is about characteristic of the secondary pump and its control system. The measuring of characteristic parameter of secondary cooling pump was being done while the pump running. The pump was loading with capacity 1950 m3/hr. with ambient temperature 28.5 oC. The fault effect of public grid (PLN) such as the fluctuation of both voltage and frequency likes voltage drops (dip). Supply block out that effect of the electric motor performances directly will be analyzed. How far those faults will effect the overall performance of secondary cooling system. Analyzing. Will be done according to the control system was installed. Has be done to find the direct effects of the motor performances against the motor rotation fluctuation which run from 1450 rpm to 1475 rpm. The using of start-delta starting method with delay time about 6 seconds, is enough or not to reduce the inrush starting current also analyzed in this paper. From the research can be obtained that in the steady state condition , the electric motor runs with both power and current are still under tolerances permitted. According to the analyzed data above, it will be consider that the control system of secondary pump would be modified or not. Therefore the analyzed data can show the characteristic curve of the secondary cooling system performance

  19. Transient Side Load Analysis of Out-of-Round Film-Cooled Nozzle Extensions

    Science.gov (United States)

    Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike

    2012-01-01

    There was interest in understanding the impact of out-of-round nozzle extension on the nozzle side load during transient startup operations. The out-of-round nozzle extension could be the result of asymmetric internal stresses, deformation induced by previous tests, and asymmetric loads induced by hardware attached to the nozzle. The objective of this study was therefore to computationally investigate the effect of out-of-round nozzle extension on the nozzle side loads during an engine startup transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary flow properties derived from an engine system simulation. Six three-dimensional cases were performed with the out-of-roundness achieved by three different degrees of ovalization, elongated on lateral y and z axes: one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation line jump was the primary source of the peak side loads. Comparing to the peak side load of the perfectly round nozzle, the peak side loads increased for the slightly and more ovalized nozzle extensions, and either increased or decreased for the two significantly ovalized nozzle extensions. A theory based on the counteraction of the flow destabilizing effect of an exacerbated asymmetrical flow caused by a lower degree of ovalization, and the flow stabilizing effect of a more symmetrical flow, created also by ovalization, is presented to explain the observations obtained in this effort.

  20. Formation of VO{sub 2} by rapid thermal annealing and cooling of sputtered vanadium thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ba, Cheikhou O. F., E-mail: cheikhou.ba.1@ulaval.ca; Fortin, Vincent; Bah, Souleymane T.; Vallée, Réal [Centre d' optique, photonique et laser (COPL), Université Laval, Québec G1V 0A6 (Canada); Pandurang, Ashrit [Thin Films and Photonics Research Group (GCMP), Department of Physics and Astronomy, Université de Moncton, Moncton, New Brunswick E1A 3E9 (Canada)

    2016-05-15

    Sputtered vanadium-rich films were subjected to rapid thermal annealing-cooling (RTAC) in air to produce vanadium dioxide (VO{sub 2}) thin films with thermochromic switching behavior. High heating and cooling rates in the thermal oxidation process provided an increased ability to control the film's microstructure. X-ray diffraction patterns of the films revealed less intense VO{sub 2} peaks compared to traditional polycrystalline samples fabricated with a standard (slower) cooling time. Such films also exhibit a high optical switching reflectance contrast, unlike the traditional polycrystalline VO{sub 2} thin films, which show a more pronounced transmittance switching. The authors find that the RTAC process stabilizes the VO{sub 2} (M2) metastable phase, enabling a rutile-semiconductor phase transition (R-M2), followed by a semiconductor–semiconductor phase transition (M2-M1).

  1. Performance of the Conduction-Cooled LDX Levitation Coil

    Science.gov (United States)

    Michael, P. C.; Schultz, J. H.; Smith, B. A.; Titus, P. H.; Radovinsky, A.; Zhukovsky, A.; Hwang, K. P.; Naumovich, G. J.; Camille, R. J.

    2004-06-01

    The Levitated Dipole Experiment (LDX) was developed to study plasma confinement in a dipole magnetic field. Plasma is confined in the magnetic field of a 680-kg Nb3Sn Floating Coil (F-coil) that is electromagnetically supported at the center of a 5-m diameter by 3-m tall vacuum chamber. The Levitation Coil (L-coil) is a 2800-turn, double pancake winding that supports the weight of the F-coil and controls its vertical position within the vacuum chamber. The use of high-temperature superconductor (HTS) Bi-2223 for the L-coil minimizes the electrical and cooling power needed for levitation. The L-coil winding pack and support plate are suspended within the L-coil cryostat and cooled by conduction to a single-stage cryocooler rated for 25-W heat load at approximately 20 K. The coil current leads consist of conduction-cooled copper running from room temperature to 80 K and a pair of commercially-available, 150-A HTS leads. An automatically filled liquid-nitrogen reservoir provides cooling for the coil's radiation shield and for the leads' 80-K heat stations. This paper discusses the L-coil system design and its observed cryogenic performance.

  2. Thermodynamic performance optimization of a combined power/cooling cycle

    International Nuclear Information System (INIS)

    Pouraghaie, M.; Atashkari, K.; Besarati, S.M.; Nariman-zadeh, N.

    2010-01-01

    A combined thermal power and cooling cycle has already been proposed in which thermal energy is used to produce work and to generate a sub-ambient temperature stream that is suitable for cooling applications. The cycle uses ammonia-water mixture as working fluid and is a combination of a Rankine cycle and absorption cycle. The very high ammonia vapor concentration, exiting turbine under certain operating conditions, can provide power output as well as refrigeration. In this paper, the goal is to employ multi-objective algorithms for Pareto approach optimization of thermodynamic performance of the cycle. It has been carried out by varying the selected design variables, namely, turbine inlet pressure (P h ), superheater temperature (T superheat ) and condenser temperature (T condensor ). The important conflicting thermodynamic objective functions that have been considered in this study are turbine work (w T ), cooling capacity (q cool ) and thermal efficiency (η th ) of the cycle. It is shown that some interesting and important relationships among optimal objective functions and decision variables involved in the combined cycle can be discovered consequently. Such important relationships as useful optimal design principles would have not been obtained without the use of a multi-objective optimization approach.

  3. Fuel performance and fission product behaviour in gas cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-11-01

    The Co-ordinated Research Programme (CRP) on Validation of Predictive Methods for Fuel and Fission Product Behaviour was organized within the frame of the International Working Group on Gas Cooled Reactors. This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs), and supports the conduct of these activities. The objectives of this CRP were to review and document the status of the experimental data base and of the predictive methods for GCR fuel performance and fission product behaviour; and to verify and validate methodologies for the prediction of fuel performance and fission product transport. Refs, figs, tabs.

  4. Fuel performance and fission product behaviour in gas cooled reactors

    International Nuclear Information System (INIS)

    1997-11-01

    The Co-ordinated Research Programme (CRP) on Validation of Predictive Methods for Fuel and Fission Product Behaviour was organized within the frame of the International Working Group on Gas Cooled Reactors. This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs), and supports the conduct of these activities. The objectives of this CRP were to review and document the status of the experimental data base and of the predictive methods for GCR fuel performance and fission product behaviour; and to verify and validate methodologies for the prediction of fuel performance and fission product transport

  5. Experimental evaluation of cooling efficiency of the high performance cooling device

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2016-06-01

    This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

  6. Experimental evaluation of cooling efficiency of the high performance cooling device

    Energy Technology Data Exchange (ETDEWEB)

    Nemec, Patrik, E-mail: patrik.nemec@fstroj.uniza.sk; Malcho, Milan, E-mail: milan.malcho@fstroj.uniza.sk [University of Žilina, Faculty of Mechanical Engineering, Department of Power Engineering, Univerzitna 1, 010 26 Žilina (Slovakia)

    2016-06-30

    This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

  7. Effects of Cooling on the Reproductive Performance of Gilts ...

    African Journals Online (AJOL)

    PROF HORSFALL

    with 3 systems of cooling, namely Wallow Cooling (WC), Sprinkler Cooling (SC) ... piggery would help to increase litter size, improve feed intake per litter and ... temperature on the productivity of livestock, experts ... Cooling (SC) and Zero Cooling (ZC) applied to sows ... consumed for body maintenance and growth by gilts.

  8. 16 CFR Appendix H to Part 305 - Cooling Performance and Cost for Central Air Conditioners

    Science.gov (United States)

    2010-01-01

    ... RULEâ) Pt. 305, App. H Appendix H to Part 305—Cooling Performance and Cost for Central Air Conditioners... Split System Units Central Air Conditioners (Cooling Only): All capacities 10.9 23.0 Heat Pumps (Cooling... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Cooling Performance and Cost for Central Air...

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

    Directory of Open Access Journals (Sweden)

    Xie Yong-Hui

    2016-01-01

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

  10. Convective Heat Transfer with and without Film Cooling in High Temperature, Fuel Rich and Lean Environments

    Science.gov (United States)

    2014-09-01

    Figure 3.2: Control panel used in experimental facility the controller throttles a solenoid valve until the desired flow rate is achieved. Finally...test objectives. Namely, quartz windows enabled visual spectrum images or laser diagnostics of reacting film cooling layers. Additionally, a sapphire...rate by a solenoid which throttled a valve restrict the flow appropriately. To measure the flow, the controllers pass the bulk flow through a

  11. Numerical Simulation of Reactive Flows in Overexpanded Supersonic Nozzle with Film Cooling

    Directory of Open Access Journals (Sweden)

    Mohamed Sellam

    2015-01-01

    Full Text Available Reignition phenomena occurring in a supersonic nozzle flow may present a crucial safety issue for rocket propulsion systems. These phenomena concern mainly rocket engines which use H2 gas (GH2 in the film cooling device, particularly when the nozzle operates under over expanded flow conditions at sea level or at low altitudes. Consequently, the induced wall thermal loads can lead to the nozzle geometry alteration, which in turn, leads to the appearance of strong side loads that may be detrimental to the rocket engine structural integrity. It is therefore necessary to understand both aerodynamic and chemical mechanisms that are at the origin of these processes. This paper is a numerical contribution which reports results from CFD analysis carried out for supersonic reactive flows in a planar nozzle cooled with GH2 film. Like the experimental observations, CFD simulations showed their ability to highlight these phenomena for the same nozzle flow conditions. Induced thermal load are also analyzed in terms of cooling efficiency and the results already give an idea on their magnitude. It was also shown that slightly increasing the film injection pressure can avoid the reignition phenomena by moving the separation shock towards the nozzle exit section.

  12. Heat Transfer Measurements for a Film Cooled Turbine Vane Cascade

    Science.gov (United States)

    2008-05-01

    Performance of Turbine Airfoils. Journal of Turbomachinery 1998, 120, 522– 529. Arnone, A.; Liou, M.-S.; Povinelli , L. A. Multigrid Calculation of... Povinelli , L. A. Development of an Explicit Multiblock/Multigrid Flow Solver for Viscous Flows in Complex Geometries; AIAA-93-2380; 1993. Wilcox, D. C

  13. Convective Performance of Nanofluids in Commercial Electronics Cooling Systems

    International Nuclear Information System (INIS)

    Roberts, N.A.; Walker, D.G.

    2010-01-01

    Nanofluids are stable engineered colloidal suspensions of a small fraction of nanoparticles in a base fluid. Nanofluids have shown great promise as heat transfer fluids over typically used base fluids and fluids with micron sized particles. Suspensions with micron sized particles are known to settle rapidly and cause clogging and damage to the surfaces of pumping and flow equipment. These problems are dramatically reduced in nanofluids. In the current work we investigate the performance of different volume loadings of water-based alumina nanofluids in a commercially available electronics cooling system. The commercially available system is a water block used for liquid cooling of a computational processing unit. The size of the nanoparticles in the study is 20-30 nm. Results show an enhancement in convective heat transfer due to the addition of nanoparticles in the commercial cooling system with volume loadings of nanoparticles up to 1.5% by volume. The enhancement in the convective performance observed is similar to what has been reported in well controlled and understood systems and is commensurate with bulk models. The current nanoparticle suspensions showed visible signs of settling which varied from hours to weeks depending on the size of the particles used.

  14. Hydrodynamic stability of thermoviscous liquid film inside a rotating horizontal cylinder: Heating and cooling effects

    Science.gov (United States)

    Kumawat, Tara Chand; Tiwari, Naveen

    2018-03-01

    Steady two-dimensional solutions and their stability analysis are presented for thin film of a thermoviscous liquid flowing inside a cylinder rotating about its horizontal axis. The inner surface of the cylinder is either uniformly hotter or colder than the enveloping air. The mass, momentum, and energy equations are simplified using thin-film approximation. The analytically obtained film thickness evolution equation consists of various dimensionless parameters such as gravitational number, Bond number, Biot number, thermoviscosity number, and Marangoni number. The viscosity of the liquid is considered as an exponential function of temperature. The viscosity increases (decreases) within the film thickness away from the inner surface of the cylinder when the surface is uniformly hotter (colder) than the atmosphere. For hotter (colder) surface, the film thickness on the rising side decreases (increases) when convective heat transfer at the free surface is increased. The surface tension gradient at the free surface generates Marangoni stress that has a destabilizing (stabilizing) effect on the thin film flow in the case of a hotter (colder) cylinder. The thermoviscosity number stabilizes (destabilizes) the flow on a heating (cooling) surface and this effect increases with an increase in the heat transfer at the free surface. For a hotter surface and in the presence of Marangoni stress, the convective heat transfer at the interface has the destabilizing effect for small values of the Biot number and assumes a stabilizing role for larger values. Non-linear simulations show consistency with the linear stability analysis.

  15. A saw-tooth plasma actuator for film cooling efficiency enhancement of a shaped hole

    Science.gov (United States)

    Li, Guozhan; Yu, Jianyang; Liu, Huaping; Chen, Fu; Song, Yanping

    2017-08-01

    This paper reports the large eddy simulations of the effects of a saw-tooth plasma actuator and the laidback fan-shaped hole on the film cooling flow characteristics, and the numerical results are compared with a corresponding standard configuration (cylindrical hole without the saw-tooth plasma actuator). For this numerical research, the saw-tooth plasma actuator is installed just downstream of the cooling hole and a phenomenological plasma model is employed to provide the 3D plasma force vectors. The results show that thanks to the downward force and the momentum injection effect of the saw-tooth plasma actuator, the cold jet comes closer to the wall surface and extends further downstream. The saw-tooth plasma actuator also induces a new pair of vortex which weakens the strength of the counter-rotating vortex pair (CRVP) and entrains the coolant towards the wall, and thus the diffusion of the cold jet in the crossflow is suppressed. Furthermore, the laidback fan-shaped hole reduces the vertical jet velocity causing the disappearance of downstream spiral separation node vortices, this compensates for the deficiency of the saw-tooth plasma actuator. Both effects of the laidback fan-shaped hole and the saw-tooth plasma actuator effectively control the development of the CRVP whose size and strength are smaller than those of the anti-counter rotating vortex pair in the far field, thus the centerline and the spanwise-averaged film cooling efficiency are enhanced. The average film cooling efficiency is the biggest in the Fan-Dc = 1 case, which is 80% bigger than that in the Fan-Dc = 0 case and 288% bigger than that in the Cyl-Dc = 0 case.

  16. Computer Simulation Performed for Columbia Project Cooling System

    Science.gov (United States)

    Ahmad, Jasim

    2005-01-01

    This demo shows a high-fidelity simulation of the air flow in the main computer room housing the Columbia (10,024 intel titanium processors) system. The simulation asseses the performance of the cooling system and identified deficiencies, and recommended modifications to eliminate them. It used two in house software packages on NAS supercomputers: Chimera Grid tools to generate a geometric model of the computer room, OVERFLOW-2 code for fluid and thermal simulation. This state-of-the-art technology can be easily extended to provide a general capability for air flow analyses on any modern computer room. Columbia_CFD_black.tiff

  17. Transient Performance of Air-cooled Condensing Heat Exchanger in Long-term Passive Cooling System during Decay Heat Load

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myoung Jun; Lee, Hee Joon [Kookmin University, Seoul (Korea, Republic of); Moon, Joo Hyung; Bae, Youngmin; Kim, Young-In [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    In the event of a 'loss of coolant accident'(LOCA) and a non-LOCA, the secondary passive cooling system would be activated to cool the steam in a condensing heat exchanger that is immersed in an emergency cooldown tank (ECT). Currently, the capacities of these ECTs are designed to be sufficient to remove the sensible and residual heat from the reactor coolant system for 72 hours after the occurrence of an accident. After the operation of a conventional passive cooling system for an extended period, however, the water level falls as a result of the evaporation from the ECT, as steam is emitted from the open top of the tank. Therefore, the tank should be refilled regularly from an auxiliary water supply system when the system is used for more than 72 hours. Otherwise, the system would fail to dissipate heat from the condensing heat exchanger due to the loss of the cooling water. Ultimately, the functionality of the passive cooling system would be seriously compromised. As a passive means of overcoming the water depletion in the tank, Kim et al. applied for a Korean patent covering the concept of a long-term passive cooling system for an ECT even after 72 hours. This study presents transient performance of ECT with installing air-cooled condensing heat exchanger under decay heat load. The cooling capacity of an air-cooled condensing heat exchanger was evaluated to determine its practicality.

  18. Performance enhancement of PV cells through micro-channel cooling

    Directory of Open Access Journals (Sweden)

    Muzaffar Ali

    2015-11-01

    Full Text Available Efficiency of a PV cell is strongly dependent on its surface temperature. The current study is focused to achieve maximum efficiency of PV cells even in scorching temperatures in hot climates like Pakistan where the cell surface temperatures can even rise up to around 80 ℃. The study includes both the CFD and real time experimental investigations of a solar panel using micro channel cooling. Initially, CFD analysis is performed by developing a 3D model of a Mono-Crystalline cell with micro-channels to analyze cell surface temperature distribution at different irradiance and water flow rates. Afterwards, an experimental setup is developed for performance investigations under the real conditions of an open climate of a Pakistan's city, Taxila. Two 35W panels are manufactured for the experiments; one is based on the standard manufacturing procedure while other cell is developed with 4mm thick aluminum sheet having micro-channels of cross-section of 1mm by 1mm. The whole setup also includes different sensors for the measurement of solar irradiance, cell power, surface temperature and water flow rates. The experimental results show that PV cell surface temperature drop of around 15 ℃ is achieved with power increment of around 14% at maximum applied water flow rate of 3 LPM. Additionally, a good agreement is also found between CFD and experimental results. Therefore, that study clearly shows that a significant performance improvement of PV cells can be achieved through the proposed cell cooling technique.

  19. Neck-cooling improves repeated sprint performance in the heat

    Directory of Open Access Journals (Sweden)

    Caroline eSunderland

    2015-11-01

    Full Text Available The present study evaluated the effect of neck-cooling during exercise on repeated sprint ability in a hot environment. Seven team-sport playing males completed two experimental trials involving repeated sprint exercise (5 x 6 s before and after two 45 min bouts of a football specific intermittent treadmill protocol in the heat (33.0  0.2 ºC; 53 ± 2% relative humidity. Participants wore a neck-cooling collar in one of the trials (CC. Mean power output and peak power output declined over time in both trials but were higher in CC (540 ± 99 v 507 ± 122W, d = 0.32; 719 ± 158 v 680 ± 182 W, d = 0.24 respectively. The improved power output was particularly pronounced (d = 0.51 – 0.88 after the 2nd 45 min bout but the CC had no effect on % fatigue. The collar lowered neck temperature and the thermal sensation of the neck (P 0.05. There were no trial differences but interaction effects were demonstrated for prolactin concentration and rating of perceived exertion (RPE. Prolactin concentration was initially higher in the collar cold trial and then was lower from 45 minutes onwards (interaction trial x time P=0.04. RPE was lower during the football intermittent treadmill protocol in the collar cold trial (interaction trial x time P = 0.01. Neck-cooling during exercise improves repeated sprint performance in a hot environment without altering physiological or neuroendocrinological responses. RPE is reduced and may partially explain the performance improvement.

  20. Effect of pre-cooling, with and without thigh cooling, on strain and endurance exercise performance in the heat.

    Science.gov (United States)

    Cotter, J D; Sleivert, G G; Roberts, W S; Febbraio, M A

    2001-04-01

    Body cooling before exercise (i.e. pre-cooling) reduces physiological strain in humans during endurance exercise in temperate and warm environments, usually improving performance. This study examined the effectiveness of pre-cooling humans by ice-vest and cold (3 degrees C) air, with (LC) and without (LW) leg cooling, in reducing heat strain and improving endurance performance in the heat (35 degrees C, 60% RH). Nine habitually-active males completed three trials, involving pre-cooling (LC and LW) or no pre-cooling (CON: 34 degrees C air) before 35-min cycle exercise: 20 min at approximately 65% VO2peak then a 15-min work-performance trial. At exercise onset, mean core (Tc, from oesophagus and rectum) and skin temperatures, forearm blood flow (FBF), heart rate (HR), and ratings of exertion, body temperature and thermal discomfort were lower in LW and LC than CON (Pcooling by ice-vest and cold air effectively reduced physiological and psychophysical strain and improved endurance performance in the heat, irrespective of whether thighs were warmed or cooled.

  1. Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

    Science.gov (United States)

    Ji, Yongbin; Ma, Chao; Ge, Bing; Zang, Shusheng

    2016-08-01

    A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

  2. Further investigation on the performance of a shower cooling tower

    International Nuclear Information System (INIS)

    Qi Xiaoni; Liu Zhenyan

    2008-01-01

    This study was prompted by the need to design towers for applications in which, due to salt deposition on the packing and subsequent blockage, the use of tower packing is not practical. In the previous model we presented [Qi Xiaoni, Liu Zhenyan, Li Dandan. Performance characteristics of a shower cooling tower. Energy Convers Manage 2007;48(1):193-203.], three critical assumptions were made to reduce the complexity and computational time, which can also reduce the models' accuracy. Accurate modelling of the operating process is a determining factor both for designing the shower cooling tower (SCT) and for optimising its operation. In this paper, we derive a new model without applying the three assumptions. According to the condition of the outlet air, the governing equations consider two cases, including the supersaturated and unsaturated states. This model is used to predict the performance of a full scale SCT located in China with different conditions for validation. The differences in the heat and mass transfer analyses of the two models are described at different atmospheric conditions

  3. Economic performance optimization of an absorption cooling system under uncertainty

    International Nuclear Information System (INIS)

    Gebreslassie, Berhane H.; Guillen-Gosalbez, Gonzalo; Jimenez, Laureano; Boer, Dieter

    2009-01-01

    Many of the strategies devised so far to address the optimization of energy systems are deterministic approaches that rely on estimated data. However, in real world applications there are many sources of uncertainty that introduce variability into the decision-making problem. Within this general context, we propose a novel approach to address the design of absorption cooling systems under uncertainty in the energy cost. As opposed to other approaches that optimize the expected performance of the system as a single objective, in our method the design task is formulated as a stochastic bi-criteria non-linear optimization problem that simultaneously accounts for the minimization of the expected total cost and the financial risk associated with the investment. The latter criterion is measured by the downside risk, which avoids the need to define binary variables thus improving the computational performance of the model. The capabilities of the proposed modeling framework and solution strategy are illustrated in a case study problem that addresses the design of a typical absorption cooling system. Numerical results demonstrate that the method presented allows to manage the risk level effectively by varying the area of the heat exchangers of the absorption cycle. Specifically, our strategy allows identifying the optimal values of the operating and design variables of the cycle that make it less sensitive to fluctuations in the energy price, thus improving its robustness in the face of uncertainty.

  4. Evaluation of the RSG-GAS cooling tower performance

    International Nuclear Information System (INIS)

    Suroso

    2003-01-01

    Utilization of RSG-GAS reactor should be operated as efficiently as possible, so that reactor operation planning using one line primary coolant can be anticipated. To analyze the performance of the RSG-GAS cooling tower with one line primary coolant doing by using same data from 10 MW thermal reactor operation. The result were then compare to those achieved using CATHENA code. The results indicated that, for design condition the ratio of water flowrate to air is (L/G) 1.52 and number transfer unit (NTU) is 0.348. For operation condition, the average of L/G and NTU are respectively 1.37 and 0,348. Moreover the results achieved by the code showed that L/G and NTU are respectively 1.35 and 0,302. The performance of cooling tower achieved operation condition and the code results are respectively 91% and 72%. This means that the calculated results are lower than measurement results

  5. Performance characteristic of hybrid cooling system based on cooling pad and evaporator

    Science.gov (United States)

    Yoon, J. I.; Son, C. H.; Choi, K. H.; Kim, Y. B.; Sung, Y. H.; Roh, S. J.; Kim, Y. M.; Seol, S. H.

    2018-01-01

    In South Korea, most of domestic animals such as pigs and chickens might die due to thermal diseases if they are exposed to the high temperature consistently. In order to save them from the heat wave, numerous efforts have been carried out: installing a shade net, adjusting time of feeding, spraying mist and setting up a circulation fan. However, these methods have not shown significant improvements. Thus, this study proposes a hybrid cooling system combining evaporative cooler and air-conditioner in order to resolve the conventional problems caused by the high temperature in the livestock industry. The problem of cooling systems using evaporative cooling pads is that they are not effective for eliminating huge heat load due to their limited capacity. And, temperature of the supplied air cannot be low enough compared to conventional air-conditioning systems. On the other hand, conventional air-conditioning systems require relatively expensive installation cost, and high operating cost compared to evaporative cooling system. The hybrid cooling system makes up for the lack of cooling capacity of the evaporative cooler by employing the conventional air-conditioner. Additionally, temperature of supplied air can be lowered enough. In the hybrid cooling system, induced air by a fan is cooled by the evaporation of water in the cooling pad, and it is cooled again by an evaporator in the air-conditioner. Therefore, the more economical operation is possible due to additionally obtained cooling capacity from the cooling pads. Major results of experimental analysis of hybrid cooling system are as follows. The compressor power consumption of the hybrid cooling system is about 23% lower, and its COP is 17% higher than that of the conventional air-conditioners. Regarding the condition of changing ambient temperature, the total power consumption decreased by about 5% as the ambient temperature changed from 28.7°C to 31.7°C. Cooling capacity and COP also presented about 3% and 1

  6. Optimal thermal-hydraulic performance for helium-cooled divertors

    International Nuclear Information System (INIS)

    Izenson, M.G.; Martin, J.L.

    1996-01-01

    Normal flow heat exchanger (NFHX) technology offers the potential for cooling divertor panels with reduced pressure drops (<0.5% Δp/p), reduced pumping power (<0.75% pumping/thermal power), and smaller duct sizes than conventional helium heat exchangers. Furthermore, the NFHX can easily be fabricated in the large sizes required for divertors in large tokamaks. Recent experimental and computational results from a program to develop NFHX technology for divertor coolings using porous metal heat transfer media are described. We have tested the thermal and flow characteristics of porous metals and identified the optimal heat transfer material for the divertor heat exchanger. Methods have been developed to create highly conductive thermal bonds between the porous material and a solid substrate. Computational fluid dynamics calculations of flow and heat transfer in the porous metal layer have shown the capability of high thermal effectiveness. An 18-kW NFHX, designed to meet specifications for the international Thermonuclear Experimental Reactor divertor, has been fabricated and tested for thermal and flow performance. Preliminary results confirm design and fabrication methods. 11 refs., 12 figs., 1 tab

  7. Coarse Grid Modeling of Turbine Film Cooling Flows Using Volumetric Source Terms

    Science.gov (United States)

    Heidmann, James D.; Hunter, Scott D.

    2001-01-01

    The recent trend in numerical modeling of turbine film cooling flows has been toward higher fidelity grids and more complex geometries. This trend has been enabled by the rapid increase in computing power available to researchers. However, the turbine design community requires fast turnaround time in its design computations, rendering these comprehensive simulations ineffective in the design cycle. The present study describes a methodology for implementing a volumetric source term distribution in a coarse grid calculation that can model the small-scale and three-dimensional effects present in turbine film cooling flows. This model could be implemented in turbine design codes or in multistage turbomachinery codes such as APNASA, where the computational grid size may be larger than the film hole size. Detailed computations of a single row of 35 deg round holes on a flat plate have been obtained for blowing ratios of 0.5, 0.8, and 1.0, and density ratios of 1.0 and 2.0 using a multiblock grid system to resolve the flows on both sides of the plate as well as inside the hole itself. These detailed flow fields were spatially averaged to generate a field of volumetric source terms for each conservative flow variable. Solutions were also obtained using three coarse grids having streamwise and spanwise grid spacings of 3d, 1d, and d/3. These coarse grid solutions used the integrated hole exit mass, momentum, energy, and turbulence quantities from the detailed solutions as volumetric source terms. It is shown that a uniform source term addition over a distance from the wall on the order of the hole diameter is able to predict adiabatic film effectiveness better than a near-wall source term model, while strictly enforcing correct values of integrated boundary layer quantities.

  8. influence of sub-cooling on the energy performance of two eco

    African Journals Online (AJOL)

    PUBLICATIONS1

    frigerants, consistently exhibited better performance than R22 in sub-cooling heat ... 2014 Kwame Nkrumah University of Science and Technology (KNUST) ... sales volume among all refrigerants. .... The sub-cooling heat exchanger affects the.

  9. TRAC analysis of passive containment cooling system performance

    International Nuclear Information System (INIS)

    Arai, Kenji; Kataoka, Kazuyoshi; Nagasaka, Hideo

    1993-01-01

    A passive containment cooling system (PCCS) is a promising concept to improve the reliability of decay heat removal during an accident. Toshiba has carried out analytical studies for PCCS development in addition to experimental studies, using a best estimate thermal hydraulic computer code TRAC. In order to establish an analytical model for the PCCS performance analysis, it is necessary for the analytical model to be qualified against experimental results and thoroughly address the phenomena important for PCCS performance analysis. In this paper, the TRAC qualification for PCCS application is reported. A TRAC model has been verified against a drain line break simulation test conducted at the PCCS integral test facility, GIRAFFE. The result shows that the TRAC model can accurately predict the major system response and the PCCS performance in the drain line break test. In addition, the results of several sensitivity analyses, showing various points concerning the modeling in the PCCS performance analysis, have been reported. The analyses have been carried out for the SBWR and the analytical points are closely related to important phenomena which can affect PCCS performance

  10. Unit thermal performance of atmospheric spray cooling systems

    International Nuclear Information System (INIS)

    Porter, R.W.; Jain, M.; Chaturvedi, S.K.

    1980-01-01

    Thermal performance of an open atmospheric spray pond or canal depends on the direct-contact evaporative cooling of an individual spray unit (spray nozzle or module) and the interference caused by local heating and humidification. Droplet parameters may be combined into a dimensionless group, number of transfer units (NTU) or equivalent, whereas large-scale air-vapor dynamics determine interference through the local wet-bulb temperature. Quantity NTU were implied from field experiments for a floating module used in steam-condenser spray canals. Previous data were available for a fixed-pipe nozzle assembly used in spray ponds. Quantity NTU were also predicted using the Ranz-Marshall correlations with the Sauter-mean diameter used as the characteristic length. Good agreement with experiments was shown for diameters of 1--1.1 cm (module) and 1.9 mm

  11. The SNS Resonance Control Cooling System Control Valve Upgrade Performance

    International Nuclear Information System (INIS)

    Williams, Derrick C.; Schubert, James Phillip; Tang, Johnny Y.

    2008-01-01

    The normal-conducting linac of the Spallation Neutron Source (SNS) uses 10 separate Resonance Control Cooling System (RCCS) water skids to control the resonance of 6 Drift Tube Linac (DTL) and 4 Coupled Cavity Linac (CCL) accelerating structures. The RCCS water skids use 2 control valves; one to regulate the chilled water flow and the other to bypass water to a chilled water heat exchanger. These valves have hydraulic actuators that provide position and feedback to the control system. Frequency oscillations occur using these hydraulic actuators due to their coarse movement and control of the valves. New pneumatic actuator and control positioners have been installed on the DTL3 RCCS water skid to give finer control and regulation of DTL3 cavity temperature. This paper shows a comparison of resonance control performance for the two valve configurations.

  12. Thermodynamic analysis of turbine blade cooling on the performance of gas turbine cycle

    International Nuclear Information System (INIS)

    Sarabchi, K.; Shokri, M.

    2002-01-01

    Turbine inlet temperature strongly affects gas turbine performance. Today blade cooling technologies facilitate the use of higher inlet temperatures. Of course blade cooling causes some thermodynamic penalties that destroys to some extent the positive effect of higher inlet temperatures. This research aims to model and evaluate the performance of gas turbine cycle with air cooled turbine. In this study internal and transpiration cooling methods has been investigated and the penalties as the result of gas flow friction, cooling air throttling, mixing of cooling air flow with hot gas flow, and irreversible heat transfer have been considered. In addition, it is attempted to consider any factor influencing actual conditions of system in the analysis. It is concluded that penalties due to blade cooling decrease as permissible temperature of the blade surface increases. Also it is observed that transpiration method leads to better performance of gas turbine comparing to internal cooling method

  13. Thermal performance measurements on ultimate heat sinks--cooling ponds

    International Nuclear Information System (INIS)

    Hadlock, R.K.; Abbey, O.B.

    1977-12-01

    The primary objective of the studies described is to obtain the requisite data, with respect to modeling requirements, to characterize thermal performance of heat sinks for nuclear facilities existing at elevated water temperatures in result of experiencing a genuinely large heat load and responding to meteorological influence. The data should reflect thermal performance for combinations leading to worst-case meteorological influence. A geothermal water retention basin has been chosen as the site for the first measurement program and data have been obtained in the first of several experiments scheduled to be performed there. These data illustrate the thermal and water budgets during episodes of cooling from an initially high pond water bulk temperature. Monitoring proceeded while the pond experienced only meteorological and seepage influence. The data are discussed and are presented as a data volume which may be used for calculation purposes. Suggestions for future measurement programs are stated with the intent to maintain and improve relevance to nuclear ultimate heat sinks while continuing to examine the performance of the analog geothermal pond. It is further suggested that the geothermal pond, with some modification, may be a suitable site for spray pond measurements

  14. Film cooling effects on the tip flow characteristics of a gas turbine blade

    Directory of Open Access Journals (Sweden)

    Jin Wang

    2015-03-01

    Full Text Available An experimental investigation of the tip flow characteristics between a gas turbine blade tip and the shroud was conducted by a pressure-test system and a particle image velocimetry (PIV system. A three-times scaled profile of the GE-E3 blade with five film cooling holes was used as specimen. The effects on flow characteristics by the rim width and the groove depth of the squealer tip were revealed. The rim widths were (a 0.9%, (b 2.1%, and (c 3.0% of the axial chord, and the groove depths were (a 2.8%, (b 4.8%, and (c 10% of the blade span. Several pressure taps on the top plate above the blades were connected to pressure gauges. By a CCD camera the PIV system recorded the velocity field around the leading edge zone including the five cooling holes. The flow distributions both in the tip clearance and in the passage were revealed, and the influence of the inlet velocity was determined. In this work, the tip flow characteristics with and without film cooling were investigated. The effects of different global blowing ratios of M=0.5, 1.0, 1.3 and 2.5 were established. It was found that decreasing the rim width resulted in a lower mass flow rate of the leakage flow, and the pressure distributions from the leading edge to the trailing edge showed a linearly increasing trend. It was also found that if the inlet velocity was less than 1.5 m/s, the flow field in the passage far away from the suction side appeared as a stagnation zone.

  15. Performance assesment of solar heating and cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Shesho, Igor; Armenski, Slave [Faculty of Mechanical Engineering, ' Ss. Cyril and Methodius' University, Skopje (Macedonia, The Former Yugoslav Republic of); others, and

    2014-07-01

    Thermal performance of the solar thermal systems are estimated using numerical methods and software since the solar processes are transitient in nature been driven by time dependent forcing functions and loads. The system components are defined with mathematical relationships that describe how components function. They are based on the first principles (energy balances, mass balances, rate equations and equilibrium relationships) at one extreme or empirical curve fits to operating data from specific machines such as absorption chillers. The component models are programed, i.e. they represent written subroutines which are simultaneously solved with the executive program. In this paper for executive program is chosen TRNSYS containing library with solar thermal system component models. Validation of the TRNSYS components models is performed, i.e. the simulation results are compared with experimental measurements. Analysis is performed for solar assisted cooling system in order to determine the solar fractions and efficiencies for different collector types, areas and storage tanks. Specific indicators are derived in order to facilitate the techno-economic analysis and design of solar air-conditioning systems. (Author)

  16. Long Hole Film Cooling Dataset for CFD Development . Part 1; Infrared Thermography and Thermocouple Surveys

    Science.gov (United States)

    Shyam, Vikram; Thurman, Douglas; Poinsatte, Phillip; Ameri, Ali; Eichele, Peter; Knight, James

    2013-01-01

    An experiment investigating flow and heat transfer of long (length to diameter ratio of 18) cylindrical film cooling holes has been completed. In this paper, the thermal field in the flow and on the surface of the film cooled flat plate is presented for nominal freestream turbulence intensities of 1.5 and 8 percent. The holes are inclined at 30deg above the downstream direction, injecting chilled air of density ratio 1.0 onto the surface of a flat plate. The diameter of the hole is 0.75 in. (0.01905 m) with center to center spacing (pitch) of 3 hole diameters. Coolant was injected into the mainstream flow at nominal blowing ratios of 0.5, 1.0, 1.5, and 2.0. The Reynolds number of the freestream was approximately 11,000 based on hole diameter. Thermocouple surveys were used to characterize the thermal field. Infrared thermography was used to determine the adiabatic film effectiveness on the plate. Hotwire anemometry was used to provide flowfield physics and turbulence measurements. The results are compared to existing data in the literature. The aim of this work is to produce a benchmark dataset for Computational Fluid Dynamics (CFD) development to eliminate the effects of hole length to diameter ratio and to improve resolution in the near-hole region. In this report, a Time-Filtered Navier Stokes (TFNS), also known as Partially Resolved Navier Stokes (PRNS), method that was implemented in the Glenn-HT code is used to model coolant-mainstream interaction. This method is a high fidelity unsteady method that aims to represent large scale flow features and mixing more accurately.

  17. Performance of cold compressors in a cooling system of an R and D superconducting coil cooled with subcooled helium

    International Nuclear Information System (INIS)

    Hamaguchi, S.; Imagawa, S.; Yanagi, N.; Takahata, K.; Maekawa, R.; Mito, T.

    2006-01-01

    The helical coils of large helical device (LHD) have been operated in saturated helium at 4.4 K and plasma experiments have been carried out at magnetic fields lower than 3 T for 8 years. Now, it is considered that the cooling system of helical coils will be improved to enhance magnetic fields in 2006. In the improvement, the helical coils will be cooled with subcooled helium and the operating temperature of helical coils will be lowered to achieve the designed field of 3 T and enhance cryogenic stabilities. Two cold compressors will be used in the cooling system of helical coils to generate subcooled helium. In the present study, the performance of cold compressors has been investigated, using a cooling system of R and D coil, to apply cold compressors to the cooling system of helical coils. Actual surge lines of cold compressors were observed and the stable operation area was obtained. Automatic operations were also performed within the area. In the automatic operations, the suitable pressure of a saturated helium bath, calculated from the rotation speed of the 1st cold compressor, was regulated by bypass valve. From these results, stable operations will be expected in the cooling system of helical coils

  18. Computational Analysis of Droplet Mass and Size Effect on Mist/Air Impingement Cooling Performance

    Directory of Open Access Journals (Sweden)

    Zhenglei Yu

    2013-01-01

    Full Text Available Impingement cooling has been widely employed to cool gas turbine hot components such as combustor liners, combustor transition pieces, turbine vanes, and blades. A promising technology is proposed to enhance impingement cooling with water droplets injection. However, previous studies were conducted on blade shower head film cooling, and less attention was given to the transition piece cooling. As a continuous effort to develop a realistic mist impingement cooling scheme, this paper focuses on simulating mist impingement cooling under typical gas turbine operating conditions of high temperature and pressure in a double chamber model. Furthermore, the paper presents the effect of cooling effectiveness by changing the mass and size of the droplets. Based on the heat-mass transfer analogy, the results of these experiments prove that the mass of 3E – 3 kg/s droplets with diameters of 5–35 μm could enhance 90% cooling effectiveness and reduce 122 K of wall temperature. The results of this paper can provide guidance for corresponding experiments and serve as the qualification reference for future more complicated studies with convex surface cooling.

  19. Experimental study on direct-contact liquid film cooling simulated dense-array solar cells in high concentrating photovoltaic system

    International Nuclear Information System (INIS)

    Wang, Yiping; Shi, Xusheng; Huang, Qunwu; Cui, Yong; Kang, Xue

    2017-01-01

    Highlights: • Direct-contact liquid film cooling dense-array solar cells was first proposed. • Average temperature was controlled well below 80 °C. • The maximum temperature difference was less than 10 °C. • The heat transfer coefficient reached up to 11.91 kW/(m"2·K) under 589X. - Abstract: This paper presented a new method of cooling dense-array solar cells in high concentrating photovoltaic system by direct-contact liquid film, and water was used as working fluid. An electric heating plate was designed to simulate the dense-array solar cells in high concentrating photovoltaic system. The input power of electric heating plate simulated the concentration ratios. By heat transfer experiments, the effect of water temperatures and flow rates on heat transfer performance was investigated. The results indicated that: the average temperature of simulated solar cells was controlled well below 80 °C under water temperature of 30 °C and flow rate of 300 L/h when concentration ratio ranged between 300X and 600X. The maximum temperature difference among temperature measurement points was less than 10 °C, which showed the temperature distribution was well uniform. The heat transfer coefficient reached up to 11.91 kW/(m"2·K) under concentration ratio of 589X. To improve heat transfer performance and obtain low average temperature of dense-array solar cells, lower water temperature and suitable water flow rate are preferred.

  20. WASA-BOSS. Development and application of Severe Accident Codes. Evaluation and optimization of accident management measures. Subproject D. Study on water film cooling for PWR's passive containment cooling system. Final report

    International Nuclear Information System (INIS)

    Huang, Xi

    2016-07-01

    In the present study, a new phenomenological model was developed, to describe the water film flow under conditions of a passive containment cooling system (PCCS). The new model takes two different flow regimes into consideration, i.e. continuous water film and rivulets. For water film flow, the traditional Nusselt's was modified, to consider orientation angle and surface sheer stress. The transition from water film to rivulet as well as the structure of the stable rivulet at its onset point was modeled by using the minimum energy principle (MEP) combined with conservation equations. In addition, two different contact angles, i.e. advancing angle and retreating angle, were applied to take the hysteresis effect into consideration. The models of individual processes were validated as far as possible based on experimental data selected from open literature and from collaboration partner as well. With the models a new program module was developed and implemented into the COCOSYS program. The extended COCOSYS program was applied to analyze the containment behavior of the European generic containment and the performance of the passive containment cooling system ofthe AP1000. The results indicate clearly the importance of the new model and provide information for the optimization of the PCCS of AP1000.

  1. WASA-BOSS. Development and application of Severe Accident Codes. Evaluation and optimization of accident management measures. Subproject D. Study on water film cooling for PWR's passive containment cooling system. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xi

    2016-07-15

    In the present study, a new phenomenological model was developed, to describe the water film flow under conditions of a passive containment cooling system (PCCS). The new model takes two different flow regimes into consideration, i.e. continuous water film and rivulets. For water film flow, the traditional Nusselt's was modified, to consider orientation angle and surface sheer stress. The transition from water film to rivulet as well as the structure of the stable rivulet at its onset point was modeled by using the minimum energy principle (MEP) combined with conservation equations. In addition, two different contact angles, i.e. advancing angle and retreating angle, were applied to take the hysteresis effect into consideration. The models of individual processes were validated as far as possible based on experimental data selected from open literature and from collaboration partner as well. With the models a new program module was developed and implemented into the COCOSYS program. The extended COCOSYS program was applied to analyze the containment behavior of the European generic containment and the performance of the passive containment cooling system ofthe AP1000. The results indicate clearly the importance of the new model and provide information for the optimization of the PCCS of AP1000.

  2. Effect mechanism of air deflectors on the cooling performance of dry cooling tower with vertical delta radiators under crosswind

    International Nuclear Information System (INIS)

    Zhao, Yuanbin; Long, Guoqing; Sun, Fengzhong; Li, Yan; Zhang, Cuijiao; Liu, Jiabin

    2015-01-01

    Highlights: • A 3D numerical model was set for NDDCTV to study the effect of air deflectors. • The air deflectors improve the tower performance by 1.375 °C at u c = 6 m/s for a case. • The air deflectors reduce the air inflow deviation angle θ d at most delta entries. • The reduced θ d can improve the cooling performance of former deteriorated columns. • Both the radial inflow air velocity and θ d impact the cooling performance of delta. - Abstract: To study the effect mechanism of air deflectors on dry cooling tower, a three dimensional numerical model was established, with full consideration of the delta structure. The accuracy and credibility of dry cooling tower numerical model were validated. By numerical model, the average air static pressure and the average radial inflow air velocity were computed and analyzed at delta air entry, sector air entry and exit faces. By the air inflow deviation angle θ d , the effect of air deflectors on the aerodynamic field around tower was analyzed. The water exit temperatures of θ −1 columns, θ +2 columns and cooling sectors were also presented to clarify the effect of air deflectors. It was found that the air deflectors improved the aerodynamic field around cooling columns. The reduced air inflow deviation degree at delta entry improved the cooling performance of deteriorated columns. Referring to the radial inflow air velocity u ra and the air inflow deviation degree at delta entry, the effect mechanism of air deflectors are clarified under crosswind

  3. Performance of a compact solar absorption cooling system

    International Nuclear Information System (INIS)

    Mulyanef; Kamaruzzaman Sopian

    2006-01-01

    This paper describes the performance of a compact solar absorption system. Purpose of compact solar is collector, generator and condenser in one unit. At present, two types of absorption cooling systems are marketed: the lithium bromide-water system and the ammonia-water system. In the lithium bromide-water system, water vapor is the refrigerant and ammonia water system where ammonia is the refrigerant. In addition, the ammonia-water system requires higher generator temperature 120 o C to 150 o C than a flat-plate solar collector can provide without special techniques. The lithium bromide-water system operates satisfactorily at a generator temperature of 75 o C to 100 o C, achievable by a flat-plate collector. The lithium bromide-water system also has a higher COP than the ammonia-water system. The disadvantage of the lithium bromide-water systems is that the evaporators cannot operate at temperature below 0 o C since the refrigerant is water. The Coefficient of Performance (COP) system is 0.62 and the concentration of LiBr-H 2 O is 50%

  4. Cooling performance of R510A in domestic water purifiers

    International Nuclear Information System (INIS)

    Park, Ki Jung; Lee, Yo Han; Jung, Dong Soo

    2010-01-01

    Cooling performance of R510A is examined both numerically and experimentally in an effort to replace HFC134a in the refrigeration system of domestic water purifiers. Although the use of HFC134a is currently dominant, it is being phased out in Europe and most developed countries due to its high potential contribution to global warming. To solve this problem, cycle simulation and experimental measurements are conducted with a new refrigerant mixture of 88%RE170/12%R600a using actual domestic water purifiers. This mixture has been recently numbered and listed as R510A by ASHRAE. Test results show that, due to the small internal volume of the refrigeration system of the domestic water purifiers, system performance with R510A is greatly influenced by the amount of charge. With the optimum charge amount of 20 to 21 g, approximately 50% that of HFC134a, the energy consumption of R510A is 22.3% lower than that of HFC134a. The compressor discharge temperature of R510A is 3.7 .deg. C lower than that of HFC134a at the optimum charge. Overall, R510A, a new, long term, and environmentally safe refrigerant, is a good alternative for HFC134a. Furthermore, it requires only minor changes in the refrigeration system of the domestic water purifiers

  5. Performance analysis of solar air cooled double effect LiBr/H2O absorption cooling system in subtropical city

    International Nuclear Information System (INIS)

    Li, Zeyu; Ye, Xiangyang; Liu, Jinping

    2014-01-01

    Highlights: • The meteorological data during the working period of air conditioning was measured. • The suitable working range of collector temperature of system was gotten. • The characteristic of hourly and monthly total efficiency of system were obtained. • The yearly performance of system was calculated. - Abstract: Due to the absence of cooling tower and independent on water, the air cooled solar double effect LiBr/H 2 O absorption cooling system is more convenient to be used in commercial building and household use. The performance with collector temperature is an important field for such system. The paper mainly deals with the performance with collector temperature for the solar air cooled double effect LiBr/H 2 O absorption cooling system in subtropical city. The parameters of system are: aperture area of collector array is 27 m 2 , tilted angle of collector with respect to the horizontal plane is 20 toward to south evaporator temperature is 5 °C and the cooling capacity is 20 kW. The simulation is based on the meteorological data of monthly typical day which was summarized from a year round measured data. A corresponding parametric model was developed. The hourly and average performance with the collector temperature for monthly typical day was obtained and discussed. It was found that the suitable working range of inlet temperature of collector is 110–130 °C to improve performance and lower the risk of crystallization. The difference of hourly total efficiency in 9:00–16:00 is less, and the monthly total efficiency from May to October is approximate. The yearly performance of system including total efficiency, cooling capacity per area of collector and solar fraction was given. Furthermore, the effect of effectiveness of heat exchanger and pressure drop on total efficiency and solar fraction was studied and compared. The paper can serve as a preliminary investigation of solar air cooled double effect LiBr/H 2 O absorption cooling system in

  6. Flame-Sprayed Y2O3 Films with Metal-EDTA Complex Using Various Cooling Agents

    Science.gov (United States)

    Komatsu, Keiji; Toyama, Ayumu; Sekiya, Tetsuo; Shirai, Tomoyuki; Nakamura, Atsushi; Toda, Ikumi; Ohshio, Shigeo; Muramatsu, Hiroyuki; Saitoh, Hidetoshi

    2017-01-01

    In this study, yttrium oxide (Y2O3) films were synthesized from a metal-ethylenediaminetetraacetic (metal-EDTA) complex by employing a H2-O2 combustion flame. A rotation apparatus and various cooling agents (compressed air, liquid nitrogen, and atomized purified water) were used during the synthesis to control the thermal history during film deposition. An EDTA·Y·H complex was prepared and used as the staring material for the synthesis of Y2O3 films with a flame-spraying apparatus. Although thermally extreme environments were employed during the synthesis, all of the obtained Y2O3 films showed only a few cracks and minor peeling in their microstructures. For instance, the Y2O3 film synthesized using the rotation apparatus with water atomization units exhibited a porosity of 22.8%. The maximum film's temperature after deposition was 453 °C owing to the high heat of evaporation of water. Cooling effects of substrate by various cooling units for solidification was dominated to heat of vaporization, not to unit's temperatures.

  7. Performance of water distribution systems in a pilot cooling tower

    International Nuclear Information System (INIS)

    Tognotti, L.; Giacomelli, A.; Zanelli, S.; Bellagamba, B.; Lotti, G.; Mattachini, F.

    1990-01-01

    An experimental study has been carried out on the water distribution system of a Pilot cooling tower of 160 m 3 /hr The performances of different industrial water distributors have been evaluated by changing the operative conditions of the pilot tower. In particular, the efficiency and the uniformity of the water distribution have been investigated and compared with the results obtained in a small-scale loop, in which the single nozzles were tested. Measurements in both systems, pilot tower and small scale loop, included the geometric characteristics of the jet umbrella by ensemble photography, the wetted zone by measuring the specific flowrate, the drop-size distribution and liquid concentration by high-speed photography. The results show that correlations exist between the nozzle behaviour in single and pilot tower configuration. The uniformity of water distribution in the pilot tower is strongly related to the nozzle installation pattern and to the operative conditions. Coalescence plays an important role on the drop size distribution in the pilot-tower. Comments upon the influence of these parameters on tower behaviour are also included

  8. Cooling During Exercise: An Overlooked Strategy for Enhancing Endurance Performance in the Heat.

    Science.gov (United States)

    Stevens, Christopher J; Taylor, Lee; Dascombe, Ben J

    2017-05-01

    It is well established that endurance performance is negatively affected by environmental heat stress due to a complex interaction of physical, physiological and psychological alterations. Numerous scientific investigations have attempted to improve performance in the heat with pre-cooling (cooling prior to an exercise test), and as such this has become a well-established ergogenic practice for endurance athletes. However, the use of mid-cooling (cooling during an exercise test) has received considerably less research attention in comparison, despite recent evidence to suggest that the advantage gained from mid-cooling may outweigh that of pre-cooling. A range of mid-cooling strategies are beneficial for endurance performance in the heat, including the ingestion of cold fluids and ice slurry, both with and without menthol, as well as cooling of the neck and face region via a cooling collar or water poured on the head and face. The combination of pre-cooling and mid-cooling has also been effective, but few comparisons exist between the timing and type of such interventions. Therefore, athletes should experiment with a range of suitable mid-cooling strategies for their event during mock competition scenarios, with the aim to determine their individual tolerable limits and performance benefits. Based on current evidence, the effect of mid-cooling on core temperature appears largely irrelevant to any subsequent performance improvements, while cardiovascular, skin temperature, central nervous system function and psychophysiological factors are likely involved. Research is lacking on elite athletes, and as such it is currently unclear how this population may benefit from mid-cooling.

  9. Cooling Performance of TBM-shield Designed for Manufacturability

    International Nuclear Information System (INIS)

    Park, Seong Dae; Lee, Dong Won; Kim, Dong Jun; Yoon, Jae Sung; Ahn, Mu Young

    2016-01-01

    Helium cooled ceramic reflector (HCCR) test blanket module (TBM) is composed of four sub-modules and a common back manifold (BM). The associated shield is a water-cooled 316L(N)-IG block with internal cooling channels. The purpose of the TBM-shield is to make the condition with the allowable neutron flux and dose rate level. The radially continuous layers of water and structure were configured. The main purpose of the shield is to reduce the neutron flux by absorbing the neutron in the structure. The water could act as the moderator and cool down the structure which is heated due to the reaction with the neutrons. The moderated neutrons are easily absorbed by the structure. It could meet the criteria for the minimum neutron flux by increasing the thickness of structure. The formation of inside cooling channel in the TBM-shield should be considered while maintaining the allowable temperature range. In this work, a manufacturing process including the formation of inside cooling channel was presented. Current design and thermal analysis results for the TBM-shield were presented. The geometry of the shield blocks was considerably changed. The coolant channel was exposed to the outer surface of the TBM-shield. The overall manufacturing process is simplified compared with the previous process of CD model

  10. Cooling Performance of TBM-shield Designed for Manufacturability

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seong Dae; Lee, Dong Won; Kim, Dong Jun; Yoon, Jae Sung [KAERI, Daejeon (Korea, Republic of); Ahn, Mu Young [NFRI, Daejeon (Korea, Republic of)

    2016-05-15

    Helium cooled ceramic reflector (HCCR) test blanket module (TBM) is composed of four sub-modules and a common back manifold (BM). The associated shield is a water-cooled 316L(N)-IG block with internal cooling channels. The purpose of the TBM-shield is to make the condition with the allowable neutron flux and dose rate level. The radially continuous layers of water and structure were configured. The main purpose of the shield is to reduce the neutron flux by absorbing the neutron in the structure. The water could act as the moderator and cool down the structure which is heated due to the reaction with the neutrons. The moderated neutrons are easily absorbed by the structure. It could meet the criteria for the minimum neutron flux by increasing the thickness of structure. The formation of inside cooling channel in the TBM-shield should be considered while maintaining the allowable temperature range. In this work, a manufacturing process including the formation of inside cooling channel was presented. Current design and thermal analysis results for the TBM-shield were presented. The geometry of the shield blocks was considerably changed. The coolant channel was exposed to the outer surface of the TBM-shield. The overall manufacturing process is simplified compared with the previous process of CD model.

  11. Modeling the methane hydrate formation in an aqueous film submitted to steady cooling

    Energy Technology Data Exchange (ETDEWEB)

    Avendano-Gomez, J.R. [ESIQIE, Laboratorio de Ingenieria Quimica Ambiental, Mexico (Mexico). Inst. Politecnico Nacional; Garcia-Sanchez, F. [Laboratorio de Termodinamica, Mexico (Mexico). Inst. Mexicano del Petroleo; Gurrola, D.V. [UPIBI, Laboratorio de Diseno de Plantas, Mexico (Mexico). Inst. Politecnico Nacional

    2008-07-01

    Gas hydrates, or clathrate hydrates, are ice-like compounds that results from the kinetic process of crystallization of an aqueous solution supersaturated with a dissolved gas. This paper presented a model that took into account two factors involved in the hydrate crystallization, notably the stochastic nature of crystallization that causes sub-cooling and the heat resulting from the exothermic enthalpy of hydrate formation. The purpose of this study was to model the thermal evolution inside a hydrate forming system which was submitted to an imposed steady cooling. The study system was a cylindrical thin film of aqueous solution at 19 Mpa. The study involved using methane as the hydrate forming molecule. It was assumed that methane was homogeneously dissolved in the aqueous phase. Ethane hydrate was formed through a kinetic process of nucleation and crystallization. In order to predict the onset time of nucleation, the induction time needed to be considered. This paper discussed the probability of nucleation as well as the estimation of the rate of nucleation. It also presented the mathematical model and boundary conditions. These included assumptions and derivation of the model; boundary conditions; initial conditions; and numerical solution of the model equation. It was concluded that the heat source must be considered when investigating crystallization effects. 34 refs., 2 tabs., 2 figs.

  12. Experimental study on supersonic film cooling on the surface of a blunt body in hypersonic flow

    International Nuclear Information System (INIS)

    Fu Jia; Yi Shi-He; Wang Xiao-Hu; He Lin; Ge Yong

    2014-01-01

    The experimental study focuses on the heat flux on a double cone blunt body in the presence of tangential-slot supersonic injection into hypersonic flow. The tests are conducted in a contoured axisymmetric nozzle with Mach numbers of 7.3 and 8.1, and the total temperature is about 900 K. The injection Mach number is 3.2, and total temperature is 300 K. A constant voltage circuit is developed to supply the temperature detectors instead of the normally used constant current circuit. The schlieren photographs are presented additionally to visualize the flow and help analyze the pressure relationship between the cooling flow and the main flow. The dependence of the film-cooling effectiveness on flow parameters, i.e. the blow ratio, the convective Mach number, and the attack angle, is determined. A semi-empirical formula is tested by the present data, and is improved for a better correlation. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  13. Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Fleeter, S.; Lawless, P.B. [Purdue Univ., West Lafayette, IN (United States)

    1995-10-01

    The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. This requires experiments in appropriate research facilities in which complete flow field data, not only point measurements, are obtained and analyzed. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows.

  14. Improving the cooling performance of electrical distribution transformer using transformer oil – Based MEPCM suspension

    OpenAIRE

    Mushtaq Ismael Hasan

    2017-01-01

    In this paper the electrical distribution transformer has been studied numerically and the effect of outside temperature on its cooling performance has been investigated. The temperature range studied covers the hot climate regions. 250 KVA distribution transformer is chosen as a study model. A novel cooling fluid is proposed to improve the cooling performance of this transformer, transformer oil-based microencapsulated phase change materials suspension is used with volume concentration (5–25...

  15. A simpler, safer, higher performance cooling system arrangement for water cooled divertors

    International Nuclear Information System (INIS)

    Carelli, M.D.; Kothmann, R.E.; Green, L.; Zhan, N.J.; Stefani, F.; Roidt, R.M.

    1994-01-01

    A cooling system arrangement is presented which is specifically designed for high heat flux water cooled divertors. The motivation behind the proposed open-quotes unichannelclose quotes configuration is to provide maximum safety; this design eliminates flow instabilities liable to occur in parallel channel designs, it eliminates total blockage, it promotes cross flow to counteract the effects of partial blockage and/or local hot spots, and it is much more tolerant to the effects of debonding between the beryllium armor and the copper substrate. Added degrees of freedom allow optimization of the design, including the possibility of operating at very high heat transfer coefficients associated with nucleate boiling, while at the same time providing ample margin against departure from nucleate boiling. Projected pressure drop, pumping power, and maximum operating temperatures are lower than for conventional parallel channel designs

  16. Design and performance prediction of an adsorption heat pump with multi-cooling tubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.C.; Zhang, J.P. [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China)

    2009-05-15

    Widespread application of adsorption heat pumps has been delayed not only by poor heat and mass transfer performance but also by low operating reliability because high vacuum must be maintained in the adsorption cooling system, especially in a water system. An adsorption cooling tube is a tube in which an adsorber, a condenser and an evaporator are all completely housed to construct a small scale adsorption cooling unit. In this work, an adsorption cooling tube and an adsorption heat pump with multi-cooling tubes are designed. A theoretical model is built to simulate the performance of the designed chiller. According to the results, the coefficient of performance and specific cooling power reach about 0.5 and 85 W/kg adsorbent, respectively, at the hot water temperature of 85 C. These results indicate that the designed heat pump in this work would provide a better choice if the operating reliability became crucial for an adsorption heat pump. (author)

  17. Design and performance prediction of an adsorption heat pump with multi-cooling tubes

    International Nuclear Information System (INIS)

    Wang, D.C.; Zhang, J.P.

    2009-01-01

    Widespread application of adsorption heat pumps has been delayed not only by poor heat and mass transfer performance but also by low operating reliability because high vacuum must be maintained in the adsorption cooling system, especially in a water system. An adsorption cooling tube is a tube in which an adsorber, a condenser and an evaporator are all completely housed to construct a small scale adsorption cooling unit. In this work, an adsorption cooling tube and an adsorption heat pump with multi-cooling tubes are designed. A theoretical model is built to simulate the performance of the designed chiller. According to the results, the coefficient of performance and specific cooling power reach about 0.5 and 85 W/kg adsorbent, respectively, at the hot water temperature of 85 deg. C. These results indicate that the designed heat pump in this work would provide a better choice if the operating reliability became crucial for an adsorption heat pump.

  18. Performance evaluation of micro thermoelectric module for hot spot cooling

    International Nuclear Information System (INIS)

    Kim, Ook Joong; Lee, Kong Hoon

    2008-01-01

    The experimental and numerical study is carried out to investigate the availability of micro TEM for hot spot cooling of an IC chip. It is found that an acrylic plate integrating with copper plate and imbedded micro TEM represents good hot spot cooling of the IC chip when CO2 laser is used to hot spot heating. Effective active local cooling phenomena by the TEM are well investigated by experiment. The measured temperature drop in the hot spot point is compared to numerical result using the TAS program for every case. Numerical result shows good agreement with experiment using some appropriate thermal and thermoelectric properties of TEM and TIM obtained by trial and error. Measurement of thermo-physical properties such as contact thermal resistance and thickness of liquid TIM is difficult but can be estimated by numerical analysis

  19. Passive cooling in modern nuclear reactors

    International Nuclear Information System (INIS)

    Rouai, N. M.

    1998-01-01

    This paper presents some recent experimental results performed with the aim of understanding the mechanism of passive cooling. The AP 600 passive containment cooling system is simulated by an electrically heated vertical pipe, which is cooled by a naturally induced air flow and by a water film descending under gravity. The results demonstrate that although the presence of the water film improved the heat transfer significantly, the mode of heat transfer was very dependent on the experimental parameters. Preheating the water improved both film stability and overall cooling performance

  20. Optimal control and performance test of solar-assisted cooling system

    KAUST Repository

    Huang, B.J.; Yen, C.W.; Wu, J.H.; Liu, J.H.; Hsu, H.Y.; Petrenko, V.O.; Chang, J.M.; Lu, C.W.

    2010-01-01

    temperature. This will make the SACH always produce cooling effect even at lower solar radiation periods while the ejector performs at off-design conditions. The energy saving of A/C is experimentally shown 50-70% due to the cooling performance of ECS

  1. performance evaluation of a composite-padded evaporative cooling

    African Journals Online (AJOL)

    user

    average temperature drop and saturation efficiency in the evaporative cooler during the no-load test were 5°C and 42%, ... flow rate wetting the pad and the construction material .... principle of evaporation which results in a cooling effect.

  2. Experimental investigation of cooling performance of a novel HVAC system combining natural ventilation with diffuse ceiling inlet and TABS

    DEFF Research Database (Denmark)

    Yu, Tao; Heiselberg, Per Kvols; Lei, Bo

    2015-01-01

    Highlights •An experimental investigation of cooling performance of a combined HVAC system is carried out. •Cooling performance of TABS with and without the influence of diffuse ceiling is analyzed. •Radiant and convective heat transfer coefficients of TABS cooling are studied. •Cooling components...

  3. Water spray cooling technique applied on a photovoltaic panel: The performance response

    International Nuclear Information System (INIS)

    Nižetić, S.; Čoko, D.; Yadav, A.; Grubišić-Čabo, F.

    2016-01-01

    Highlights: • An experimental study was conducted on a monocrystalline photovoltaic panel (PV). • A water spray cooling technique was implemented to determine PV panel response. • The experimental results showed favorable cooling effect on the panel performance. • A feasibility aspect of the water spray cooling technique was also proven. - Abstract: This paper presents an alternative cooling technique for photovoltaic (PV) panels that includes a water spray application over panel surfaces. An alternative cooling technique in the sense that both sides of the PV panel were cooled simultaneously, to investigate the total water spray cooling effect on the PV panel performance in circumstances of peak solar irradiation levels. A specific experimental setup was elaborated in detail and the developed cooling system for the PV panel was tested in a geographical location with a typical Mediterranean climate. The experimental result shows that it is possible to achieve a maximal total increase of 16.3% (effective 7.7%) in electric power output and a total increase of 14.1% (effective 5.9%) in PV panel electrical efficiency by using the proposed cooling technique in circumstances of peak solar irradiation. Furthermore, it was also possible to decrease panel temperature from an average 54 °C (non-cooled PV panel) to 24 °C in the case of simultaneous front and backside PV panel cooling. Economic feasibility was also determined for of the proposed water spray cooling technique, where the main advantage of the analyzed cooling technique is regarding the PV panel’s surface and its self-cleaning effect, which additionally acts as a booster to the average delivered electricity.

  4. Effect of Cooling Units on the Performance of an Automotive Exhaust-Based Thermoelectric Generator

    Science.gov (United States)

    Su, C. Q.; Zhu, D. C.; Deng, Y. D.; Wang, Y. P.; Liu, X.

    2017-05-01

    Currently, automotive exhaust-based thermoelectric generators (AETEGs) are a hot topic in energy recovery. In order to investigate the influence of coolant flow rate, coolant flow direction and cooling unit arrangement in the AETEG, a thermoelectric generator (TEG) model and a related test bench are constructed. Water cooling is adopted in this study. Due to the non-uniformity of the surface temperature of the heat source, the coolant flow direction would affect the output performance of the TEG. Changing the volumetric flow rate of coolant can increase the output power of multi-modules connected in series or/and parallel as it can improve the temperature uniformity of the cooling unit. Since the temperature uniformity of the cooling unit has a strong influence on the output power, two cooling units are connected in series or parallel to research the effect of cooling unit arrangements on the maximum output power of the TEG. Experimental and theoretical analyses reveal that the net output power is generally higher with cooling units connected in parallel than cooling units connected in series in the cooling system with two cooling units.

  5. INVESTIGATION OF THE PERFORMANCE OF AN ATMOSPHERIC COOLING TOWER USING FRESH AND SALTED WATER

    Directory of Open Access Journals (Sweden)

    A Haddad

    2012-01-01

    Full Text Available Cooling towers are extensively used to evacuate large quantities of heat at modest temperatures through a change of phase of the flowing cooling fluid. Based on this classical principle, the present study investigates the influence of salty water on the heat exchange produced. For that purpose, experiments are carried out using fresh and salty water. Furthermore, a comparison with the results produced through an approach involving the solution of energy equation involving the flow of air on an evaporating film of fluid. The detailed results show a preponderance of fresh water over the salty.

  6. Performance Evaluation of a Mechanical Draft Cross Flow Cooling Towers Employed in a Subtropical Region

    Science.gov (United States)

    Muthukumar, Palanisamy; Naik, Bukke Kiran; Goswami, Amarendra

    2018-02-01

    Mechanical draft cross flow cooling towers are generally used in a large-scale water cooled condenser based air-conditioning plants for removing heat from warm water which comes out from the condensing unit. During this process considerable amount of water in the form of drift (droplets) and evaporation is carried away along with the circulated air. In this paper, the performance evaluation of a standard cross flow induced draft cooling tower in terms of water loss, range, approach and cooling tower efficiency are presented. Extensive experimental studies have been carried out in three cooling towers employed in a water cooled condenser based 1200 TR A/C plant over a period of time. Daily variation of average water loss and cooling tower performance parameters have been reported for some selected days. The reported average water loss from three cooling towers is 4080 l/h and the estimated average water loss per TR per h is about 3.1 l at an average relative humidity (RH) of 83%. The water loss during peak hours (2 pm) is about 3.4 l/h-TR corresponding to 88% of RH and the corresponding efficiency of cooling towers varied between 25% and 45%.

  7. Performance Evaluation of a Software Engineering Tool for Automated Design of Cooling Systems in Injection Moulding

    DEFF Research Database (Denmark)

    Jauregui-Becker, Juan M.; Tosello, Guido; van Houten, Fred J.A.M.

    2013-01-01

    This paper presents a software tool for automating the design of cooling systems for injection moulding and a validation of its performance. Cooling system designs were automatically generated by the proposed software tool and by applying a best practice tool engineering design approach. The two...

  8. Prediction of Film Cooling Effectiveness on a Gas Turbine Blade Leading Edge Using ANN and CFD

    Science.gov (United States)

    Dávalos, J. O.; García, J. C.; Urquiza, G.; Huicochea, A.; De Santiago, O.

    2018-05-01

    In this work, the area-averaged film cooling effectiveness (AAFCE) on a gas turbine blade leading edge was predicted by employing an artificial neural network (ANN) using as input variables: hole diameter, injection angle, blowing ratio, hole and columns pitch. The database used to train the network was built using computational fluid dynamics (CFD) based on a two level full factorial design of experiments. The CFD numerical model was validated with an experimental rig, where a first stage blade of a gas turbine was represented by a cylindrical specimen. The ANN architecture was composed of three layers with four neurons in hidden layer and Levenberg-Marquardt was selected as ANN optimization algorithm. The AAFCE was successfully predicted by the ANN with a regression coefficient R2<0.99 and a root mean square error RMSE=0.0038. The ANN weight coefficients were used to estimate the relative importance of the input parameters. Blowing ratio was the most influential parameter with relative importance of 40.36 % followed by hole diameter. Additionally, by using the ANN model, the relationship between input parameters was analyzed.

  9. 3D Measurements of coupled freestream turbulence and secondary flow effects on film cooling

    Science.gov (United States)

    Ching, David S.; Xu, Haosen H. A.; Elkins, Christopher J.; Eaton, John K.

    2018-06-01

    The effect of freestream turbulence on a single round film cooling hole is examined at two turbulence levels of 5 and 8% and compared to a baseline low freestream turbulence case. The hole is inclined at 30° and has length to diameter ratio L/D=4 and unity blowing ratio. Turbulence is generated with grid upstream of the hole in the main channel. The three-dimensional, three-component mean velocity field is acquired with magnetic resonance velocimetry (MRV) and the three-dimensional temperature field is acquired with magnetic resonance thermometry (MRT). The 8% turbulence grid produces weak mean secondary flows in the mainstream (peak crossflow velocities are 7% of U_bulk) which push the jet close to the wall and significantly change the adiabatic effectiveness distribution. By contrast, the 5% grid has a simpler structure and does not produce a measurable secondary flow structure. The grid turbulence causes little change to the temperature field, indicating that the turbulence generated in the shear layers around the jet dominates the freestream turbulence. The results suggest that secondary flows induced by complex turbulence generators may have caused some of the contradictory results in previous works.

  10. Influence of precooling cooling air on the performance of a gas turbine combined cycle

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Ik Hwan; Kang, Do Won; Kang, Soo Young; Kim, Tong Seop [Inha Univ., Incheon (Korea, Republic of)

    2012-02-15

    Cooling of hot sections, especially the turbine nozzle and rotor blades, has a significant impact on gas turbine performance. In this study, the influence of precooling of the cooling air on the performance of gas turbines and their combined cycle plants was investigated. A state of the art F class gas turbine was selected, and its design performance was deliberately simulated using detailed component models including turbine blade cooling. Off design analysis was used to simulate changes in the operating conditions and performance of the gas turbines due to precooling of the cooling air. Thermodynamic and aerodynamic models were used to simulate the performance of the cooled nozzle and rotor blade. In the combined cycle plant, the heat rejected from the cooling air was recovered at the bottoming steam cycle to optimize the overall plant performance. With a 200K decrease of all cooling air stream, an almost 1.78% power upgrade due to increase in main gas flow and a 0.70 percent point efficiency decrease due to the fuel flow increase to maintain design turbine inlet temperature were predicted.

  11. Field evaluation of performance of radiant heating/cooling ceiling panel system

    DEFF Research Database (Denmark)

    Li, Rongling; Yoshidomi, Togo; Ooka, Ryozo

    2015-01-01

    heating/coolingceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiantheating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus,this study aims to not only clarify the system performance but also to share our...... experience and our resultsfor them to serve as a reference for other similar projects. Here, the system performance in relation toits heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient fromwater to room was 3.7 W/(m2K) and 4.8 W/(m2K) for heating and cooling cases...

  12. On the optimum performance of forced draft counter flow cooling towers

    International Nuclear Information System (INIS)

    Soeylemez, M.S.

    2004-01-01

    A thermo-hydraulic performance optimization analysis is presented, yielding simple algebraic formula for estimating the optimum performance point of counter current mechanical draft wet cooling towers. The effectiveness-Ntu method is used in the present study, together with the derivation of psychometric properties of moist air based on a numerical approximation method, for thermal performance analysis of wet cooling towers of the counter flow type

  13. Performance Recovery of Natural Draft Dry Cooling Systems by Combined Air Leading Strategies

    Directory of Open Access Journals (Sweden)

    Weijia Wang

    2017-12-01

    Full Text Available The cooling efficiency of natural draft dry cooling system (NDDCS are vulnerable to ambient winds, so the implementation of measures against the wind effects is of great importance. This work presents the combined air leading strategies to recover the flow and heat transfer performances of NDDCS. Following the energy balance among the exhaust steam, circulating water, and cooling air, numerical models of natural draft dry cooling systems with the combined air leading strategies are developed. The cooling air streamlines, volume effectiveness, thermal efficiency and outlet water temperature for each cooling delta of the large-scale heat exchanger are obtained. The overall volume effectiveness, average outlet water temperature of NDDCS and steam turbine back pressure are calculated. The results show that with the air leading strategies inside or outside the dry-cooling tower, the thermo-flow performances of natural draft dry cooling system are improved under all wind conditions. The combined inner and outer air leading strategies are superior to other single strategy in the performance recovery, thus can be recommended for NDDCS in power generating units.

  14. Crosswinds Effect on the Thermal Performance of Wet Cooling Towers Under Variable Operating Conditions

    Science.gov (United States)

    Chen, You Liang; Shi, Yong Feng; Hao, Jian Gang; Chang, Hao; Sun, Feng Zhong

    2018-01-01

    In order to quantitatively analyze the influence of the variable operating parameters on the cooling performance of natural draft wet cooling towers (NDWCTs), a hot model test system was set up with adjustable ambient temperature and humidity, circulating water flowrate and temperature. In order to apply the hot model test results to the real tower, the crosswind Froude number is defined. The results show that the crosswind has a negative effect on the thermal performance of the cooling tower, and there is a critical crosswind velocity corresponding to the lowest cooling efficiency. According to the crosswind Froude number similarity, when the ambient temperature decreases, or the circulating water flowrate and temperature increase, the cooling tower draft force will increase, and the critical crosswind velocity will increase correspondingly.

  15. Numerical Study of the Effects of Thermal Barrier Coating and Turbulence Intensity on Cooling Performances of a Nozzle Guide Vane

    Directory of Open Access Journals (Sweden)

    Prasert Prapamonthon

    2017-03-01

    Full Text Available This work presents a numerical investigation of the combined effects of thermal barrier coating (TBC with mainstream turbulence intensity (Tu on a modified vane of the real film-cooled nozzle guide vane (NGV reported by Timko (NASA CR-168289. Using a 3D conjugate heat transfer (CHT analysis, the NGVs with and without TBC are simulated at three Tus (Tu = 3.3%, 10% and 20%. The overall cooling effectiveness, TBC effectiveness and heat transfer coefficient are analyzed and discussed. The results indicate the following three interesting phenomena: (1 TBC on the pressure side (PS is more effective than that on the suction side (SS due to a fewer number of film holes on the SS; (2 for all three Tus, the variation trends of the overall cooling effectiveness are similar, and TBC plays the positive and negative roles in heat flux at the same time, and significantly increases the overall cooling effectiveness in regions cooled ineffectively by cooling air; (3 when Tu increases, the TBC effect is more significant, for example, at the highest Tu (Tu = 20% the overall cooling effectiveness can increase as much as 24% in the film cooling ineffective regions, but near the trailing edge (TE and the exits and downstream of film holes on the SS, this phenomenon is slight.

  16. Cooling and heating performances of a CO2 heat pump with the variations of operating conditions

    International Nuclear Information System (INIS)

    Baek, Chang Hyun; Lee, Eung Chan; Kang, Hun; Kim, Yong Chan; Cho, Hong Hyun

    2008-01-01

    Since operating conditions are significantly different for heating and cooling mode operations in a CO 2 heat pump system, it is difficult to optimize the performance of the CO 2 cycle. In addition, the performance of a CO 2 heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed CO 2 heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%

  17. System performance and economic analysis of solar-assisted cooling/heating system

    KAUST Repository

    Huang, B.J.

    2011-11-01

    The long-term system simulation and economic analysis of solar-assisted cooling/heating system (SACH-2) was carried out in order to find an economical design. The solar heat driven ejector cooling system (ECS) is used to provide part of the cooling load to reduce the energy consumption of the air conditioner installed as the base-load cooler. A standard SACH-2 system for cooling load 3.5. kW (1. RT) and daily cooling time 10 h is used for case study. The cooling performance is assumed only in summer seasons from May to October. In winter season from November to April, only heat is supplied. Two installation locations (Taipei and Tainan) were examined.It was found from the cooling performance simulation that in order to save 50% energy of the air conditioner, the required solar collector area is 40m2 in Taipei and 31m2 in Tainan, for COPj=0.2. If the solar collector area is designed as 20m2, the solar ejector cooling system will supply about 17-26% cooling load in Taipei in summer season and about 21-27% cooling load in Tainan. Simulation for long-term performance including cooling in summer (May-October) and hot water supply in winter (November-April) was carried out to determine the monthly-average energy savings. The corresponding daily hot water supply (with 40°C temperature rise of water) for 20m2 solar collector area is 616-858L/day in Tainan and 304-533L/day in Taipei.The economic analysis shows that the payback time of SACH-2 decreases with increasing cooling capacity. The payback time is 4.8. years in Tainan and 6.2. years in Taipei when the cooling capacity >10. RT. If the ECS is treated as an additional device used as a protective equipment to avoid overheating of solar collectors and to convert the excess solar heat in summer into cooling to reduce the energy consumption of air conditioner, the payback time is less than 3 years for cooling capacity larger than 3. RT. © 2011 Elsevier Ltd.

  18. Modeling and performance of the MHTGR [Modular High-Temperature Gas-Cooled Reactor] reactor cavity cooling system

    International Nuclear Information System (INIS)

    Conklin, J.C.

    1990-04-01

    The Reactor Cavity Cooling System (RCCS) of the Modular High- Temperature Gas-Cooled Reactor (MHTGR) proposed by the U.S. Department of Energy is designed to remove the nuclear afterheat passively in the event that neither the heat transport system nor the shutdown cooling circulator subsystem is available. A computer dynamic simulation for the physical and mathematical modeling of and RCCS is described here. Two conclusions can be made form computations performed under the assumption of a uniform reactor vessel temperature. First, the heat transferred across the annulus from the reactor vessel and then to ambient conditions is very dependent on the surface emissivities of the reactor vessel and RCCS panels. These emissivities should be periodically checked to ensure the safety function of the RCCS. Second, the heat transfer from the reactor vessel is reduced by a maximum of 10% by the presence of steam at 1 atm in the reactor cavity annulus for an assumed constant in the transmission of radiant energy across the annulus can be expected to result in an increase in the reactor vessel temperature for the MHTGR. Further investigation of participating radiation media, including small particles, in the reactor cavity annulus is warranted. 26 refs., 7 figs., 1 tab

  19. Effect of Thermoelectric Cooling (TEC module and the water flow heatsink on Photovoltaic (PV panel performance

    Directory of Open Access Journals (Sweden)

    Amelia A.R.

    2017-01-01

    Full Text Available Photovoltaic (PV panel suffers in low conversion efficiency of the output performance affected by the elevated operating temperature of the PV panel. It is important to keep the PV panel to operate at low temperature. To address this issue, this paper proposes the cooling system using thermoelectric cooling (TEC and water block heatsink for enhancing the PV panel output performance. These both types cooling system were designed located on the back side of the PV panel to cool down the operating temperature of the PV panel. To evaluate the function for the existing cooling systems, the experiment was subsequently performed for PV panel without and with different design of the cooling system in outdoor weather conditions. By comparing the experimental results, it is concluded that by the hybrid cooling system which combining TEC module and the water block heatsink could improve the output performance of the PV panel. By the reduction temperature of the PV panel by 16.04 %, the average output power of the PV panel has been boosted up from 8.59 W to 9.03 W. In short, the output power of the PV panel was enhanced by the reduction of the operating temperature of the PV panel.

  20. Effect of Thermoelectric Cooling (TEC) module and the water flow heatsink on Photovoltaic (PV) panel performance

    Science.gov (United States)

    Amelia, A. R.; Jusoh, MA; Shamira Idris, Ida

    2017-11-01

    Photovoltaic (PV) panel suffers in low conversion efficiency of the output performance affected by the elevated operating temperature of the PV panel. It is important to keep the PV panel to operate at low temperature. To address this issue, this paper proposes the cooling system using thermoelectric cooling (TEC) and water block heatsink for enhancing the PV panel output performance. These both types cooling system were designed located on the back side of the PV panel to cool down the operating temperature of the PV panel. To evaluate the function for the existing cooling systems, the experiment was subsequently performed for PV panel without and with different design of the cooling system in outdoor weather conditions. By comparing the experimental results, it is concluded that by the hybrid cooling system which combining TEC module and the water block heatsink could improve the output performance of the PV panel. By the reduction temperature of the PV panel by 16.04 %, the average output power of the PV panel has been boosted up from 8.59 W to 9.03 W. In short, the output power of the PV panel was enhanced by the reduction of the operating temperature of the PV panel.

  1. The Effect of Variable Gravity on the Cooling Performance of a 16-Nozzle Spray Array

    National Research Council Canada - National Science Library

    Elston, Levi J; Yerkes, Kirk L; Thomas, Scott K; McQuillen, John

    2008-01-01

    The objective of this thesis was to investigate the cooling performance of a 16-nozzle spray array, using FC-72 as the working fluid, in variable gravity conditions with additional emphasis on fluid...

  2. Experimental performance of evaporative cooling pad systems in greenhouses in humid subtropical climates

    International Nuclear Information System (INIS)

    Xu, J.; Li, Y.; Wang, R.Z.; Liu, W.; Zhou, P.

    2015-01-01

    Highlights: • Experimental performance of evaporative cooling in humid climate is investigated. • 5 working modes are studied in the greenhouse. • Vertical and horizontal temperature and relative humidity variations are analysed. • Indoor temperature can be kept in required level by proper working modes. - Abstract: To solve the overheating problem caused by the solar radiation and to keep the indoor temperature and humidity at a proper level for plants or crops, cooling technologies play vital role in greenhouse industry, and among which evaporative cooling is one of the most commonly-used methods. However, the main challenge of the evaporative cooling is its suitability to local climatic and agronomic condition. In this study, the performance of evaporative cooling pads was investigated experimentally in a 2304-m 2 glass multi-span greenhouse in Shanghai in the southeast of China. Temperature and humidity distributions were measured and reported for different working modes, including the use of evaporative cooling alone and the use of evaporative cooling with shading or ventilation. These experiments were conducted in humid subtropical climates where were considered unfavourable for evaporative cooling pad systems. Quantified analyses from the energy perspective are also made based on the experimental results and the evaporative cooling fan–pad system is demonstrated to be an effective option for greenhouse cooling even in the humid climate. Suggestions and possible solutions for further improving the performance of the system are proposed. The results of this work will be useful for the optimisation of the energy management of greenhouses in humid climates and for the validation of the mathematical model in future work

  3. Effects of free-stream turbulence intensity and blowing ratio on film cooling of turbine blade leading edge

    International Nuclear Information System (INIS)

    Kim, S. M.; Kim, Youn J.; Cho, H. H.

    2001-01-01

    We used a cylindrical model which simulates turbine blade leading edge to investigate the effects of free-stream turbulence intensity and blowing ratio on film cooling of turbine blade leading edge. Tests are carried out in a low-speed wind tunnel on a cylindrical model with three rows of injection holes. Mainstream Reynolds number based on the cylinder diameter was 7.1x10 4 . Two types of turbulence grid are used to increase a free-stream turbulence intensity. The effect of coolant blowing ratio was studied for various blowing ratios. For each blowing ratios, wall temperatures around the surface of the test model are measured by thermocouples installed inside the model. Results show that blowing ratios have small effect on spanwise-averaged film effectiveness at high free-stream turbulence intensity. However, an increase in free-stream turbulence intensity enhances significantly spanwise-averaged film effectiveness at low blowing ratio

  4. Highly c-axis-oriented monocrystalline Pb(Zr, Ti)O₃ thin films on si wafer prepared by fast cooling immediately after sputter deposition.

    Science.gov (United States)

    Yoshida, Shinya; Hanzawa, Hiroaki; Wasa, Kiyotaka; Esashi, Masayoshi; Tanaka, Shuji

    2014-09-01

    We successfully developed sputter deposition technology to obtain a highly c-axis-oriented monocrystalline Pb(Zr, Ti)O3 (PZT) thin film on a Si wafer by fast cooling (~-180°C/min) of the substrate after deposition. The c-axis orientation ratio of a fast-cooled film was about 90%, whereas that of a slow-cooled (~-40°C/min) film was only 10%. The c-axis-oriented monocrystalline Pb(Zr0.5, Ti0.5)O3 films showed reasonably large piezoelectric coefficients, e(31,f) = ~-11 C/m(2), with remarkably small dielectric constants, ϵ(r) = ~220. As a result, an excellent figure of merit (FOM) was obtained for piezoelectric microelectromechanical systems (MEMS) such as a piezoelectric gyroscope. This c-axis orientation technology on Si will extend industrial applications of PZT-based thin films and contribute further to the development of piezoelectric MEMS.

  5. Numerical simulation of the effects of hanging sound absorbers on TABS cooling performance

    DEFF Research Database (Denmark)

    Rage, Nils; Kazanci, Ongun Berk; Olesen, Bjarne W.

    2016-01-01

    simulating a two-person office of 20 m2, with a typical cooling load of 42 W/m2. The results show that covering 60% of the ceiling surface with sound absorbers hanging at 300 mm from the ceiling active deck is expected to reduce the cooling capacity coefficient of TABS by 15.8%. This drops to 25......Recently there has been a considerable increase in the use of Thermally-Active Building Systems (TABS) in Europe as an energy-efficient and economical cooling and heating solution for buildings. However, this widespread solution requires large uncovered hard surfaces indoors, which can lead...... to a degradation of the room acoustic comfort. Therefore, challenges arise when this system has to be combined with acoustic requirements. Soffit-hanging sound absorbers embody a promising solution. This study focuses on quantifying their impact on the cooling performance of TABS, assessed by means of the cooling...

  6. Performance analysis for minimally nonlinear irreversible refrigerators at finite cooling power

    Science.gov (United States)

    Long, Rui; Liu, Zhichun; Liu, Wei

    2018-04-01

    The coefficient of performance (COP) for general refrigerators at finite cooling power have been systematically researched through the minimally nonlinear irreversible model, and its lower and upper bounds in different operating regions have been proposed. Under the tight coupling conditions, we have calculated the universal COP bounds under the χ figure of merit in different operating regions. When the refrigerator operates in the region with lower external flux, we obtained the general bounds (0 present large values, compared to a relative small loss from the maximum cooling power. If the cooling power is the main objective, it is desirable to operate the refrigerator at a slightly lower cooling power than at the maximum one, where a small loss in the cooling power induces a much larger COP enhancement.

  7. Performance of Metal Cutting on Endmills Manufactured by Cooling-Air and Minimum Quantity Lubrication Grinding

    Science.gov (United States)

    Inoue, Shigeru; Aoyama, Tojiro

    Grinding fluids have been commonly used during the grinding of tools for their cooling and lubricating effect since the hard, robust materials used for cutting tools are difficult to grind. Grinding fluids help prevent a drop in hardness due to burning of the cutting edge and keep chipping to an absolute minimum. However, there is a heightened awareness of the need to improve the work environment and protect the global environment. Thus, the present study is aimed at applying dry grinding, cooling-air grinding, cooling-air grinding with minimum quantity lubrication (MQL), and oil-based fluid grinding to manufacturing actual endmills (HSS-Co). Cutting tests were performed by a vertical machining center. The results indicated that the lowest surface inclination values and longest tool life were obtained by cooling-air grinding with MQL. Thus, cooling-air grinding with MQL has been demonstrated to be at least as effective as oil-based fluid grinding.

  8. Experimental study of performance of a dry cooling and dedicated ventilation (DCDV) system under different space cooling load conditions

    International Nuclear Information System (INIS)

    Jia, Jie; Lee, W.L.; Chen, Hua

    2013-01-01

    Highlights: • This is an experimental study of the use of DCDV system for achieving the decoupling and energy saving objectives. • The study focuses on side-by-side comparison of the DCDV and conventional systems. • DCDV system can better achieve the desired space air conditions and is more energy efficient. • A prediction model has been developed to relate the possible condensation period with different operating parameters. • The results are useful for wider application of DCDV system. - Abstract: The use of DCDV system for decoupling dehumidification from cooling to achieve energy saving objective for air-conditioning of office environments in Hong Kong was confirmed effective based on simulation studies by the authors. However, given that simulation typically assumes a perfect control and feedback system, whether or not the benefits of DCDV system can be realized in practice, in particular under various space part load ratio (PLR) and sensible heat ratio (SHR) conditions, is subject to experimental verifications. In this study, a prototype which could be switched between the proposed DCDV system mode and the conventional system mode was constructed in a test facility for laboratory experiments. Through two sets of identical experiments under various space cooling load conditions, it was found that if compared to the conventional system, DCDV system could perform slightly better in achieving the desired indoor condition and in reducing the moisture-related air quality problems, but would result in 1–3% higher in cooling output. As for the overall coefficient of performance (COP o ), the DCDV system was found performed better by 5.6–7.2%. Additional experimental analysis was conducted for the development of a prediction model to relate the possible condensation period (ψ) on the DC coil with different operating parameters

  9. Performance analysis of phase-change material storage unit for both heating and cooling of buildings

    Science.gov (United States)

    Waqas, Adeel; Ali, Majid; Ud Din, Zia

    2017-04-01

    Utilisation of solar energy and the night ambient (cool) temperatures are the passive ways of heating and cooling of buildings. Intermittent and time-dependent nature of these sources makes thermal energy storage vital for efficient and continuous operation of these heating and cooling techniques. Latent heat thermal energy storage by phase-change materials (PCMs) is preferred over other storage techniques due to its high-energy storage density and isothermal storage process. The current study was aimed to evaluate the performance of the air-based PCM storage unit utilising solar energy and cool ambient night temperatures for comfort heating and cooling of a building in dry-cold and dry-hot climates. The performance of the studied PCM storage unit was maximised when the melting point of the PCM was ∼29°C in summer and 21°C during winter season. The appropriate melting point was ∼27.5°C for all-the-year-round performance. At lower melting points than 27.5°C, declination in the cooling capacity of the storage unit was more profound as compared to the improvement in the heating capacity. Also, it was concluded that the melting point of the PCM that provided maximum cooling during summer season could be used for winter heating also but not vice versa.

  10. Experimental study on the thermal performance of a mechanical cooling tower with different drift eliminators

    International Nuclear Information System (INIS)

    Lucas, M.; Martinez, P.J.; Viedma, A.

    2009-01-01

    Cooling towers are equipment devices commonly used to dissipate heat from power generation units, water-cooled refrigeration, air conditioning and industrial processes. Water drift emitted from cooling towers is objectionable for several reasons, mainly due to human health hazards. It is common practice to fit drift eliminators to cooling towers in order to minimize water loss from the system. It is foreseeable that the characteristics of the installed drift eliminators, like their pressure drop, affect the thermal performance of the cooling tower. However, no references regarding this fact have been found in the reviewed bibliography. This paper studies the thermal performance of a forced draft counter-flow wet cooling tower fitted with different drift eliminators for a wide range of air and water mass flow rates. The data registered in the experimental set-up were employed to obtain correlations of the tower characteristic, which defines the cooling tower's thermal performance. The outlet water temperature predicted by these correlations was compared with the experimentally registered values obtaining a maximum difference of ±3%

  11. Performance analysis of a ground-assisted direct evaporative cooling air conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Heidarinejad, Ghassem; Khalajzadeh, Vahid [Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran); Delfani, Shahram [Building and Housing Research Center (BHRC), P O Box 13145-1696, Tehran (Iran)

    2010-11-15

    In this paper, the results of performance analysis of a ground-assisted hybrid evaporative cooling system in Tehran have been discussed. A Ground Coupled Circuit (GCC) provides the necessary pre-cooling effects, enabling a Direct Evaporative Cooler (DEC) that cools the air even below its wet-bulb temperature. The GCC includes four vertical ground heat exchangers (GHE) which were arrayed in series configuration. In order to have an accurate prediction of the optimum performance of a GCC, a computational fluid dynamic simulation was performed. Simulation results revealed that the combination of GCC and DEC system could provide comfort condition whereas DEC alone did not. Based on the simulation results the cooling effectiveness of a hybrid system is more than 100%. Thus, this novel hybrid system could decrease the air temperature below the ambient wet-bulb temperature. This environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems. (author)

  12. 3D Analysis of Cooling Performance with Loss of Offsite Power Using GOTHIC Code

    International Nuclear Information System (INIS)

    Oh, Kye Min; Heo, Gyun Young; Na, In Sik; Choi, Yu Jung

    2010-01-01

    GOTHIC code enables to analyze one-dimensional or multi-dimensional problems for evaluating the cooling performance of loss of offsite power. The conventional GOTHIC code analysis performs heat transfer between plant containment and the outside of the fan cooler tubes by modeling each of fan cooler part model and component cooling water inside tube each to analyze boiling probability. In this paper, we suggest a way which reduces the multi-procedure of the cooling performance with loss of offsite power or the heat transfer states with complex geometrical structure to a single-procedure and verify the applicability of the heat transfer differences from the containment atmosphere humidity changes by the multi-nodes which component cooling water of tube or air of Reactor Containment Fan Cooler in the containment, otherwise the component model uses only one node

  13. An analytical model on thermal performance evaluation of counter flow wet cooling tower

    Directory of Open Access Journals (Sweden)

    Wang Qian

    2017-01-01

    Full Text Available This paper proposes an analytical model for simultaneous heat and mass transfer processes in a counter flow wet cooling tower, with the assumption that the enthalpy of the saturated air is a linear function of the water surface temperature. The performance of the proposed analytical model is validated in some typical cases. The validation reveals that, when cooling range is in a certain interval, the proposed model is not only comparable with the accurate model, but also can reduce computational complexity. In addition, with the proposed analytical model, the thermal performance of the counter flow wet cooling towers in power plants is calculated. The results show that the proposed analytical model can be applied to evaluate and predict the thermal performance of counter flow wet cooling towers.

  14. A temperature rise equation for predicting environmental impact and performance of cooling ponds

    Energy Technology Data Exchange (ETDEWEB)

    Serag-Eldin, M.A. [American Univ. in Cairo, Cairo (Egypt). Dept. of Mechanical Engineering

    2009-07-01

    Cooling ponds are used to cool the condenser water used in large central air-conditioning systems. However, larger cooling loads can often increase pond surface evaporation rates. A temperature-rise energy equation was developed to predict temperature rises in cooling ponds subjected to heating loads. The equation was designed to reduce the need for detailed meteorological data as well as to determine the required surface area and depth of the pond for any given design criteria. Energy equations in the presence and absence of cooling loads were subtracted from each other to determine increases in pond temperature resulting from the cooling load. The energy equations include solar radiation, radiation exchange with sky and surroundings, heat convection from the surface, evaporative cooling, heat conducted to the walls, and rate of change of water temperature. Results of the study suggested that the environmental impact and performance of the cooling pond is a function of temperature only. It was concluded that with the aid of the calculated flow field and temperature distribution, the method can be used to position sprays in order to produce near-uniform pond temperatures. 10 refs., 12 figs.

  15. High-performance and flexible thermoelectric films by screen printing solution-processed nanoplate crystals.

    Science.gov (United States)

    Varghese, Tony; Hollar, Courtney; Richardson, Joseph; Kempf, Nicholas; Han, Chao; Gamarachchi, Pasindu; Estrada, David; Mehta, Rutvik J; Zhang, Yanliang

    2016-09-12

    Screen printing allows for direct conversion of thermoelectric nanocrystals into flexible energy harvesters and coolers. However, obtaining flexible thermoelectric materials with high figure of merit ZT through printing is an exacting challenge due to the difficulties to synthesize high-performance thermoelectric inks and the poor density and electrical conductivity of the printed films. Here, we demonstrate high-performance flexible films and devices by screen printing bismuth telluride based nanocrystal inks synthesized using a microwave-stimulated wet-chemical method. Thermoelectric films of several tens of microns thickness were screen printed onto a flexible polyimide substrate followed by cold compaction and sintering. The n-type films demonstrate a peak ZT of 0.43 along with superior flexibility, which is among the highest reported ZT values in flexible thermoelectric materials. A flexible thermoelectric device fabricated using the printed films produces a high power density of 4.1 mW/cm(2) with 60 °C temperature difference between the hot side and cold side. The highly scalable and low cost process to fabricate flexible thermoelectric materials and devices demonstrated here opens up many opportunities to transform thermoelectric energy harvesting and cooling applications.

  16. Cooling performance of a vertical ground-coupled heat pump system installed in a school building

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Yujin; Lee, Jae-Keun; Jeong, Young-Man; Koo, Kyung-Min [Department of Mechanical Engineering, Pusan National University, San 30, Jangjeon-Dong, Kumjung-Ku, Busan 609-735 (Korea); Lee, Dong-Hyuk; Kim, In-Kyu; Jin, Sim-Won [LG Electronics, 391-2 Gaeumjeong-dong, Changwon City, Gyeongnam (Korea); Kim, Soo H. [Department of Nanosystems and Nanoprocess Engineering, Pusan National University, San 30, Jangjeon-Dong, Kumjung-Ku, Busan 609-735 (Korea)

    2009-03-15

    This paper presents the cooling performance of a water-to-refrigerant type ground heat source heat pump system (GSHP) installed in a school building in Korea. The evaluation of the cooling performance has been conducted under the actual operation of GSHP system in the summer of year 2007. Ten heat pump units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. To analyze the cooling performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the cooling capacity and the input power were evaluated to determine the cooling performance of the GSHP system. The average cooling coefficient of performance (COP) and overall COP of the GSHP system were found to be {proportional_to}8.3 and {proportional_to}5.9 at 65% partial load condition, respectively. While the air source heat pump (ASHP) system, which has the same capacity with the GSHP system, was found to have the average COP of {proportional_to}3.9 and overall COP of {proportional_to}3.4, implying that the GSHP system is more efficient than the ASHP system due to its lower temperature of condenser. (author)

  17. Effect of cooling rate on the structure and properties of thick films of YBa2Cu3O7-x

    International Nuclear Information System (INIS)

    Li, S.R.; Oleinikov, N.N.; Gas'kov, A.M.

    1993-01-01

    A problem associated with the production of quality films is chemical interaction of the HTSC material with the substrate. This leads to a considerable worsening or complete loss of the superconducting properties of a functional material. A second problem is selection of a substrate whose thermal expansion coefficient (TCE) is as close as possible to the TCE of the superconducting material. Omission of this condition leads to production of a HTSC material which is subject to perturbing mechanical stresses (compressive or tensile stress), and this is a potential cause of the reduction of the functional parameters of the material. The authors note that other substrate requirements should be considered only during production of thin films. Unfortunately, the production of quality thick films is apparently not worked out with resolution of the latter two problems. It is very important in production of HTSC materials to consider the rate of cooling at the moment of formation of the orthorhombic phase (in the following, the tetragonal-orthorhombic transition). Undesirable relaxation can be avoided if the cooling rate is lowered below some critical value. According to the computations, this problem is solved most successfully in HTSC materials of the composition YBa 2 Cu 3 O 7-x if their ceramic structure consists of crystallites whose size does not exceed 1-2 μm. The goal of this work is to elucidate the effect of the cooling rate of thick films of composition YBa 2 Cu 3 O 7-x in the temperature range corresponding to transition of the tetragonal to the orthorhombic phase on their structure and properties

  18. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A.; Schiffman, Jessica D.; Elimelech, Menachem

    2010-01-01

    obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed

  19. Performance analysis on utilization of sky radiation cooling energy for space cooling. Part 2; Hosha reikyaku riyo reibo system ni kansuru kenkyu. 2

    Energy Technology Data Exchange (ETDEWEB)

    Marushima, S; Saito, T [Tohoku University, Sendai (Japan)

    1996-10-27

    Studies have been made about a heat accumulation tank type cooling system making use of radiation cooling that is a kind of natural energy. The daily operating cycle of the cooling system is described below. A heat pump air conditioner performs cooling during the daytime and the exhaust heat is stored in a latent heat accumulation tank; the heat is then used for the bath and tapwater in the evening; at night radiation cooling is utilized to remove the heat remnant in the tank for the solidification of the phase change material (PCM); the solidified PCM serves as the cold heat source for the heat pump air conditioner to perform cooling. The new system decelerates urban area warming because it emits the cooler-generated waste heat not into the atmosphere but into space taking advantage of radiation cooling. Again, the cooler-generated waste heat may be utilized for energy saving and power levelling. For the examination of nighttime radiation cooling characteristics, CaCl2-5H2O and Na2HPO4-12H2O were tested as the PCM. Water was used as the heating medium. In the case of a PCM high in latent heat capacity, some work has to be done for insuring sufficient heat exchange for it by, for instance, rendering the flow rate low. The coefficient of performance of the system discussed here is three times higher than that of the air-cooled type heat pump system. 8 refs., 5 figs., 4 tabs.

  20. Performance assessment of earth pipe cooling system for low energy buildings in a subtropical climate

    International Nuclear Information System (INIS)

    Ahmed, S.F.; Khan, M.M.K.; Amanullah, M.T.O.; Rasul, M.G.; Hassan, N.M.S.

    2015-01-01

    Highlights: • Earth pipe cooling performance was investigated in a subtropical climate in Australia. • A thermal model was developed using Fluent to assess the cooling performance. • A temperature reduction of around 2 °C was found for the earth pipe cooling system. • Annual energy savings of maximum 866.54 kW (8.82%) was achieved for a 27.23 m"3 room. - Abstract: Energy consumption in heating and cooling around the world has been a major contributor to global warming. Hence, many studies have been aimed at finding new techniques to save and control energy through energy efficient measures. Most of this energy is used in residential, agricultural and commercial buildings. It is therefore important to adopt energy efficiency measures in these buildings through new technologies and novel building designs. These new building designs can be developed by employing various passive cooling systems. Earth pipe cooling is one of these which can assist to save energy without using any customary mechanical units. This paper investigates the earth pipe cooling performance in a hot humid subtropical climate of Rockhampton, Australia. A thermal model is developed using ANSYS Fluent for measuring its performance. Impacts of air velocity, air temperature, relative humidity and soil temperature on room cooling performance are also assessed. A temperature reduction of around 2 °C was found for the system. This temperature reduction contributed to an energy saving of a maximum of 866.54 kW (8.82%) per year for a 27.23 m"3 room.

  1. Optimal control and performance test of solar-assisted cooling system

    KAUST Repository

    Huang, B.J.

    2010-10-01

    The solar-assisted cooling system (SACH) was developed in the present study. The ejector cooling system (ECS) is driven by solar heat and connected in parallel with an inverter-type air conditioner (A/C). The cooling load can be supplied by the ECS when solar energy is available and the input power of the A/C can be reduced. In variable weather, the ECS will probably operate at off-design condition of ejector and the cooling capability of the ECS can be lost completely. In order to make the ejector operate at critical or non-critical double-choking condition to obtain a better performance, an electronic expansion valve was installed in the suction line of the ejector to regulate the opening of the expansion valve to control the evaporator temperature. This will make the SACH always produce cooling effect even at lower solar radiation periods while the ejector performs at off-design conditions. The energy saving of A/C is experimentally shown 50-70% due to the cooling performance of ECS. The long-term performance test results show that the daily energy saving is around 30-70% as compared to the energy consumption of A/C alone (without solar-driven ECS). The total energy saving of A/C is 52% over the entire test period. © 2010 Elsevier Ltd. All rights reserved.

  2. Dietary Tyrosine Benefits Cognitive and Psychomotor Performance During Body Cooling

    National Research Council Canada - National Science Library

    O'Brien, Catherine; Mahoney, Caroline; Tharion, William J; Sils, Ingrid V; Castellani, John W

    2007-01-01

    ... examined. This study evaluated the effect of tyrosine supplementation on cognitive, psychomotor, and physical performance following a cold water immersion protocol that lowered body core temperature...

  3. Development of a prototype thermoelectric space cooling system using phase change material to improve the performance

    Science.gov (United States)

    Zhao, Dongliang

    The thermoelectric cooling system has advantages over conventional vapor compression cooling devices, including compact in size, light in weight, high reliability, no mechanical moving parts, no refrigerant, being powered by direct current, and easily switching between cooling and heating modes. However, it has been long suffering from its relatively high cost and low energy efficiency, which has restricted its usage to niche applications, such as space missions, portable cooling devices, scientific and medical equipment, where coefficient of performance (COP) is not as important as reliability, energy availability, and quiet operation environment. Enhancement of thermoelectric cooling system performance generally relies on two methods: improving thermoelectric material efficiency and through thermoelectric cooling system thermal design. This research has been focused on the latter one. A prototype thermoelectric cooling system integrated with phase change material (PCM) thermal energy storage unit for space cooling has been developed. The PCM thermal storage unit used for cold storage at night, functions as the thermoelectric cooling system's heat sink during daytime's cooling period and provides relatively lower hot side temperature for the thermoelectric cooling system. The experimental test of the prototype system in a reduced-scale chamber has realized an average cooling COP of 0.87, with the maximum value of 1.22. Another comparison test for efficacy of PCM thermal storage unit shows that 35.3% electrical energy has been saved from using PCM for the thermoelectric cooling system. In general, PCM faces difficulty of poor thermal conductivity at both solid and liquid phases. This system implemented a finned inner tube to increase heat transfer during PCM charging (melting) process that directly impacts thermoelectric system's performance. A simulation tool for the entire system has been developed including mathematical models for a single thermoelectric module

  4. Performance limits of direct cryogenically cooled silicon monochromators - experimental results at the APS

    International Nuclear Information System (INIS)

    Lee, W.-K.; Fernandez, P.; Mills, D.M.

    2000-01-01

    The successful use of cryogenically cooled silicon monochromators at third-generation synchrotron facilities is well documented. At the Advanced Photon Source (APS) it has been shown that, at 100 mA operation with the standard APS undulator A, the cryogenically cooled silicon monochromator performs very well with minimal (<2 arcsec) or no observable thermal distortions. However, to date there has not been any systematic experimental study on the performance limits of this approach. This paper presents experimental results on the performance limits of these directly cooled crystals. The results show that if the beam is limited to the size of the radiation central cone then, at the APS, the crystal will still perform well at twice the present 100 mA single 2.4 m-long 3.3 cm-period undulator heat load. However, the performance would degrade rapidly if a much larger incident white-beam size is utilized

  5. Computational Fluid Dynamic (CFD) analysis of axisymmetric plume and base flow of film/dump cooled rocket nozzle

    Science.gov (United States)

    Tucker, P. K.; Warsi, S. A.

    1993-01-01

    Film/dump cooling a rocket nozzle with fuel rich gas, as in the National Launch System (NLS) Space Transportation Main Engine (STME), adds potential complexities for integrating the engine with the vehicle. The chief concern is that once the film coolant is exhausted from the nozzle, conditions may exist during flight for the fuel-rich film gases to be recirculated to the vehicle base region. The result could be significantly higher base temperatures than would be expected from a regeneratively cooled nozzle. CFD analyses were conduced to augment classical scaling techniques for vehicle base environments. The FDNS code with finite rate chemistry was used to simulate a single, axisymmetric STME plume and the NLS base area. Parallel calculations were made of the Saturn V S-1 C/F1 plume base area flows. The objective was to characterize the plume/freestream shear layer for both vehicles as inputs for scaling the S-C/F1 flight data to NLS/STME conditions. The code was validated on high speed flows with relevant physics. This paper contains the calculations for the NLS/STME plume for the baseline nozzle and a modified nozzle. The modified nozzle was intended to reduce the fuel available for recirculation to the vehicle base region. Plumes for both nozzles were calculated at 10kFT and 50kFT.

  6. Transpiration and film cooling boundary layer computer program. Volume 1: Numerical solutions of the turbulent boundary layer equations with equilibrium chemistry

    Science.gov (United States)

    Levine, J. N.

    1971-01-01

    A finite difference turbulent boundary layer computer program has been developed. The program is primarily oriented towards the calculation of boundary layer performance losses in rocket engines; however, the solution is general, and has much broader applicability. The effects of transpiration and film cooling as well as the effect of equilibrium chemical reactions (currently restricted to the H2-O2 system) can be calculated. The turbulent transport terms are evaluated using the phenomenological mixing length - eddy viscosity concept. The equations of motion are solved using the Crank-Nicolson implicit finite difference technique. The analysis and computer program have been checked out by solving a series of both laminar and turbulent test cases and comparing the results to data or other solutions. These comparisons have shown that the program is capable of producing very satisfactory results for a wide range of flows. Further refinements to the analysis and program, especially as applied to film cooling solutions, would be aided by the acquisition of a firm data base.

  7. Study on performance prediction and energy saving of indirect evaporative cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Seong Yeon; Kim, Tae Ho; Kim, Myung Ho [Dept. of Mechanical Design Engineering, Chungnam National University, Daejeon (Korea, Republic of)

    2015-09-15

    The purpose of this study is to predict the performance of an indirect evaporative cooling system, and to evaluate its energy saving effect when applied to the exhaust heat recovery system of an air-handling unit. We derive the performance correlation of the indirect evaporative cooling system using a plastic heat exchanger based on experimental data obtained in various conditions. We predict the variations in the performance of the system for various return and outdoor air conditioning systems using the obtained correlation. We also analyze the energy saving of the system realized by the exhaust heat recovery using the typical meteorological data for several cities in Korea. The average utilization rate of the sensible cooling system for the exhaust heat recovery is 44.3% during summer, while that of the evaporative cooling system is 96.7%. The energy saving of the evaporative cooling system is much higher compared to the sensible cooling system, and was about 3.89 times the value obtained in Seoul.

  8. Effects of oral rehydration and external cooling on physiology, perception, and performance in hot, dry climates.

    Science.gov (United States)

    Muñoz, C X; Carney, K R; Schick, M K; Coburn, J W; Becker, A J; Judelson, D A

    2012-12-01

    Only limited research evaluates possible benefits of combined drinking and external cooling (by pouring cold water over the body) during exercise. Therefore, this study examined cold water drinking and external cooling on physiological, perceptual, and performance variables in hot, dry environments. Ten male runners completed four trials of walking 90 min at 30% VO(2max) followed by running a 5-km time trial in 33 ± 1 °C and 30 ± 4% relative humidity. Trials examined no intervention (CON), oral rehydration (OR), external cooling (EC), and oral rehydration plus external cooling (OR + EC). Investigators measured rectal temperature, skin temperatures, heart rate, thirst, thermal sensation, and ratings of perceived exertion (RPE). Oral rehydration (OR and OR + EC) significantly lowered heart rate (P External cooling (EC and OR + EC) significantly reduced chest and thigh temperature (P external cooling (CON and OR) during low-intensity exercise. Performance exhibited no differences (CON = 23.86 ± 4.57 min, OR = 22.74 ± 3.20 min, EC = 22.96 ± 3.11 min, OR + EC = 22.64 ± 3.73 min, P = 0.379). Independent of OR, pouring cold water on the body benefited skin temperature, thermal sensation, and RPE during low-intensity exercise in hot, dry conditions but failed to influence high-intensity performance. © 2012 John Wiley & Sons A/S.

  9. Improving of the photovoltaic / thermal system performance using water cooling technique

    International Nuclear Information System (INIS)

    Hussien, Hashim A; Numan, Ali H; Abdulmunem, Abdulmunem R

    2015-01-01

    This work is devoted to improving the electrical efficiency by reducing the rate of thermal energy of a photovoltaic/thermal system (PV/T).This is achieved by design cooling technique which consists of a heat exchanger and water circulating pipes placed at PV module rear surface to solve the problem of the high heat stored inside the PV cells during the operation. An experimental rig is designed to investigate and evaluate PV module performance with the proposed cooling technique. This cooling technique is the first work in Iraq to dissipate the heat from PV module. The experimental results indicated that due to the heat loss by convection between water and the PV panel's upper surface, an increase of output power is achieved. It was found that without active cooling, the temperature of the PV module was high and solar cells could only achieve a conversion efficiency of about 8%. However, when the PV module was operated under active water cooling condition, the temperature was dropped from 76.8°C without cooling to 70.1°C with active cooling. This temperature dropping led to increase in the electrical efficiency of solar panel to 9.8% at optimum mass flow rate (0.2L/s) and thermal efficiency to (12.3%). (paper)

  10. Cooling and performance recovery of trained athletes: a meta-analytical review.

    Science.gov (United States)

    Poppendieck, Wigand; Faude, Oliver; Wegmann, Melissa; Meyer, Tim

    2013-05-01

    Cooling after exercise has been investigated as a method to improve recovery during intensive training or competition periods. As many studies have included untrained subjects, the transfer of those results to trained athletes is questionable. Therefore, the authors conducted a literature search and located 21 peer-reviewed randomized controlled trials addressing the effects of cooling on performance recovery in trained athletes. For all studies, the effect of cooling on performance was determined and effect sizes (Hedges' g) were calculated. Regarding performance measurement, the largest average effect size was found for sprint performance (2.6%, g = 0.69), while for endurance parameters (2.6%, g = 0.19), jump (3.0%, g = 0.15), and strength (1.8%, g = 0.10), effect sizes were smaller. The effects were most pronounced when performance was evaluated 96 h after exercise (4.3%, g = 1.03). Regarding the exercise used to induce fatigue, effects after endurance training (2.4%, g = 0.35) were larger than after strength-based exercise (2.4%, g = 0.11). Cold-water immersion (2.9%, g = 0.34) and cryogenic chambers (3.8%, g = 0.25) seem to be more beneficial with respect to performance than cooling packs (-1.4%, g= -0.07). For cold-water application, whole-body immersion (5.1%, g = 0.62) was significantly more effective than immersing only the legs or arms (1.1%, g = 0.10). In summary, the average effects of cooling on recovery of trained athletes were rather small (2.4%, g = 0.28). However, under appropriate conditions (whole-body cooling, recovery from sprint exercise), postexercise cooling seems to have positive effects that are large enough to be relevant for competitive athletes.

  11. Performance Analyses of Counter-Flow Closed Wet Cooling Towers Based on a Simplified Calculation Method

    Directory of Open Access Journals (Sweden)

    Xiaoqing Wei

    2017-02-01

    Full Text Available As one of the most widely used units in water cooling systems, the closed wet cooling towers (CWCTs have two typical counter-flow constructions, in which the spray water flows from the top to the bottom, and the moist air and cooling water flow in the opposite direction vertically (parallel or horizontally (cross, respectively. This study aims to present a simplified calculation method for conveniently and accurately analyzing the thermal performance of the two types of counter-flow CWCTs, viz. the parallel counter-flow CWCT (PCFCWCT and the cross counter-flow CWCT (CCFCWCT. A simplified cooling capacity model that just includes two characteristic parameters is developed. The Levenberg–Marquardt method is employed to determine the model parameters by curve fitting of experimental data. Based on the proposed model, the predicted outlet temperatures of the process water are compared with the measurements of a PCFCWCT and a CCFCWCT, respectively, reported in the literature. The results indicate that the predicted values agree well with the experimental data in previous studies. The maximum absolute errors in predicting the process water outlet temperatures are 0.20 and 0.24 °C for the PCFCWCT and CCFCWCT, respectively. These results indicate that the simplified method is reliable for performance prediction of counter-flow CWCTs. Although the flow patterns of the two towers are different, the variation trends of thermal performance are similar to each other under various operating conditions. The inlet air wet-bulb temperature, inlet cooling water temperature, air flow rate, and cooling water flow rate are crucial for determining the cooling capacity of a counter-flow CWCT, while the cooling tower effectiveness is mainly determined by the flow rates of air and cooling water. Compared with the CCFCWCT, the PCFCWCT is much more applicable in a large-scale cooling water system, and the superiority would be amplified when the scale of water

  12. Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring

    OpenAIRE

    Zuo, Zheng; Hu, Yu; Li, Qingbin; Zhang, Liyuan

    2014-01-01

    Embedded cool-pipes are very important for massive concrete because their cooling effect can effectively avoid thermal cracks. In this study, a data mining approach to analyzing the thermal performance of cool-pipes via in situ monitoring is proposed. Delicate monitoring program is applied in a high arch dam project that provides a good and mass data source. The factors and relations related to the thermal performance of cool-pipes are obtained in a built theory thermal model. The supporting ...

  13. Influence of the ambient temperature on the cooling efficiency of the high performance cooling device with thermosiphon effect

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2018-06-01

    This work deal with experimental measurement and calculation cooling efficiency of the cooling device working with a heat pipe technology. The referred device in the article is cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description, working principle and construction of cooling device. The main factor affected the dissipation of high heat flux from electronic elements through the cooling device to the surrounding is condenser construction, its capacity and option of heat removal. Experimental part describe the measuring method cooling efficiency of the cooling device depending on ambient temperature in range -20 to 40°C and at heat load of electronic components 750 W. Measured results are compared with results calculation based on physical phenomena of boiling, condensation and natural convection heat transfer.

  14. Effect of wrist cooling on aerobic and anaerobic performance in elite sportsmen.

    Science.gov (United States)

    Krishnan, Anup; Singh, Krishan; Sharma, Deep; Upadhyay, Vivekanand; Singh, Amit

    2018-01-01

    Body cooling has been used to increase sporting performance and enhance recovery. Several studies have reported improvement in exercise capacities using forearm and hand cooling or only hand cooling. Wrist cooling has emerged as a portable light weight solution for precooling prior to sporting activity. The Astrand test for aerobic performance and the Wingate test for anaerobic performance are reliable and accurate tests for performance assessment. This study conducted on elite Indian athletes analyses the effects of wrist precooling on aerobic and anaerobic performance as tested by the Astrand test and the Wingate test before and after wrist precooling. 67 elite sportsmen were administered Wingate and Astrand test under standardised conditions with and without wrist precooling using a wrist cooling device (dhamaSPORT). Paired t -test was applied to study effect on aerobic [VO 2 (ml/min/kg)] and anaerobic performance [peak power (W/kg) and average power (W/kg)] and Cohen's d was used to calculate effect size of wrist precooling. After wrist precooling, significant increase of 0.22 ( p  = 0.014, 95% CI: 0.047, 0.398) in peak power (W/kg) and 0.22 ( p  effective in aerobic performance. Wrist cooling effect size was smaller in VO 2 (Cohen's d  = 0.21), peak power (Cohen's d  = 0.31) and it was larger in average power (Cohen's d  = 0.71). Results show wrist precooling significantly improves anaerobic than aerobic performance of elite sportsmen.

  15. Thermal performance of a radiatively cooled system for quantum optomechanical experiments in space

    International Nuclear Information System (INIS)

    Pilan Zanoni, André; Burkhardt, Johannes; Johann, Ulrich; Aspelmeyer, Markus; Kaltenbaek, Rainer; Hechenblaikner, Gerald

    2016-01-01

    Highlights: • We improved performance and design aspects of a radiatively cooled instrument. • A heat-flow analysis showed near optimal performance of the shield design. • A simple modification to imaging optics allowed further improvements. • We studied the thermal behavior for different orbital cases. • A transfer-function analysis showed strong attenuation of thermal variations. - Abstract: Passive cooling of scientific instruments via thermal radiation to deep space offers many advantages over active cooling in terms of mission cost, lifetime and the achievable quality of vacuum and microgravity. Motivated by the mission proposal MAQRO to test the foundations of quantum physics harnessing a deep-space environment, we investigate the performance of a radiatively cooled instrument, where the environment of a test particle in a quantum superposition has to be cooled to less than 20 K. We perform a heat-transfer analysis between the instrument components and a transfer-function analysis on thermal oscillations induced by the spacecraft interior and dissipative sources. The thermal behavior of the instrument is discussed for an orbit around a Lagrangian point and for a highly elliptical Earth orbit. Finally, we investigate possible design improvements. These include a mirror-based design of the imaging system on the optical bench (OB) and an extension of the heat shields.

  16. Presence of bias in radiographer plain film reading performance studies

    International Nuclear Information System (INIS)

    Brealey, S.; Scally, A.J.; Thomas, N.B.

    2002-01-01

    Purpose To raise awareness of the frequency of bias that can affect the quality of radiographer plain film reading performance studies. Methods Studies that assessed radiographer(s) plain film reading performance were located by searching electronic databases and grey literature, hand-searching journals, personal communication and scanning reference lists. Thirty studies were judged eligible from all data sources. Results A one-way analysis of variance (ANOVA) demonstrates no statistically significant difference (P=0.25) in the mean proportion of biases present from diagnostic accuracy (0.37), performance (0.42) and outcome (0.44) study designs. Pearson's correlation coefficient showed no statistically significant linear association between the proportion of biases present for the three different study designs and the year that the study was performed. The frequency of biases in film and observer selection and application of the reference standard was quite low. In contrast, many biases were present concerning independence of film reporting and comparison of reports for concordance. Conclusions The findings indicate variation in the presence of bias in radiographer plain film reading performance studies. The careful consideration of bias is an essential component of study quality and hence the validity of the evidence-base used to underpin radiographic reporting policy

  17. Energy Performance of Water-based and Air-based Cooling Systems in Plus-energy Housing

    DEFF Research Database (Denmark)

    Andersen, Mads E.; Schøtt, Jacob; Kazanci, Ongun Berk

    2016-01-01

    -space, and air-to-water heat pump vs. ground heat exchanger as cooling source) on the system energy performance were investigated while achieving the same thermal indoor conditions. The results show that the water-based floor cooling system performed better than the air-based cooling system in terms of energy...... energy use reductions. The coupling of radiant floor with the ground enables to obtain “free” cooling, although the brine pump power should be kept to a minimum to fully take advantage of this solution. By implementing a ground heat exchanger instead of the heat pump and use the crawl-space air as intake...... air an improvement of 37% was achieved. The cooling demand should be minimized in the design phase as a priority and then the resulting cooling load should be addressed with the most energy efficient cooling strategy. The floor cooling coupled with a ground heat exchanger was shown to be an effective...

  18. Parametric Study on an Initial Cooling Performance in the KALIMER-600

    International Nuclear Information System (INIS)

    Han, Ji-Woong; Eoh, Jae-Hyuk; Lee, Tae-Ho; Kim, Seong-O

    2009-01-01

    Decay heat removal is very important in a nuclear power plant. The KALIMER-600, Korea Advanced Liquid MEtal Reactor, employs the PDRC(Passive Decay heat Removal Circuit) to remove the decay heat. DHX(Decay Heat eXchanger) in the PDRC of KALIMER-600 is disposed in the DHX support barrel located in the hot pool region. Each DHX support barrel has the lower end communicating with the cold pool such that the sodium free surface inside the barrel is maintained with the same level of the cold pool using the pumping head of the PHTS(Primary Heat Transport System) pumps. Consequently, DHX is not in direct contact with the cold pool sodium during a normal plant operation. Under transient conditions such as the loss of a normal heat sink accident, free surface outside the barrel rises up due to the expansion of the sodium induced by the core decay heat during the initial stage cooling. When it overflows into the cold pool through the DHX support barrel the heat removal via DHX is initiated and the second stage cooling begins. In order to secure the safety of a reactor until the activation of a second stage cooling by PDRC, it is very important to suppress the core temperature rising by an enhancement of the initial cooling performance. In this study the parametric investigations have been applied to reveal the effect of various design parameters on the initial cooling performance. The various design parameters such as coastdown flow, IHX(Intermediate Heat eXchanger) elevation, heat transfer via CCS (Cavity Cooling System) were considered. The numerical approaches based on a multidimensional analysis can be utilized as a useful tool to investigate overall transient behaviors within a pool. In this research the COMMIX-1AR/P code is utilized as a transient analysis tool in KALIMER-600 after a shut down. This study will provide the basic design information to improve the initial cooling performance in the KALIMER-600

  19. Computational Study of Film Cooling Effectiveness for a Comparison of Cylindrical, Square and Triangular Holes of Equal Cross-Sectional Area

    Directory of Open Access Journals (Sweden)

    Fayyaz Hassan Asghar

    2010-10-01

    Full Text Available Film cooling effectiveness is studied computationally for a comparison of circular, square and two types of equilateral triangular holes with an inclination of 30o with streamwise direction. Reynolds number based on the freestream velocity and hole diameter is 10364. Length to diameter ratio of circular hole is 4, which is representative of gas turbine engines. The coolant to mainstream density ratio is 0.92. Main flow is supplied at the temperature of 293.15K and coolant is supplied at 318.15K. Centerline and laterally averaged effectiveness are presented for film cooling measurements. Current computational results for circular hole are compared with experimental results. Computational results are well in agreement with the experimental results even for high blowing ratios. Blowing ratios ranging from 0.33-2.0 have been investigated. It is observed that triangular hole having lateral straight edge on leeward side shows much higher effectiveness values than circular film cooling hole case in the near hole region and almost similar coolant jet height as that in case of circular film cooling. Also it is observed that triangular hole having lateral straight edge on windward side and converging corner on leeward side shows lesser coolant jet height and higher film cooling effectiveness in the region x/D>10, especially at blowing ratios greater than 1.0.

  20. Performance and economic enhancement of cogeneration gas turbines through compressor inlet air cooling

    Science.gov (United States)

    Delucia, M.; Bronconi, R.; Carnevale, E.

    1994-04-01

    Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine's power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.

  1. Improving the cooling performance of electrical distribution transformer using transformer oil – Based MEPCM suspension

    Directory of Open Access Journals (Sweden)

    Mushtaq Ismael Hasan

    2017-04-01

    Full Text Available In this paper the electrical distribution transformer has been studied numerically and the effect of outside temperature on its cooling performance has been investigated. The temperature range studied covers the hot climate regions. 250 KVA distribution transformer is chosen as a study model. A novel cooling fluid is proposed to improve the cooling performance of this transformer, transformer oil-based microencapsulated phase change materials suspension is used with volume concentration (5–25% as a cooling fluid instead of pure transformer oil. Paraffin wax is used as a phase change material to make the suspension, in addition to the ability of heat absorption due to melting, the paraffin wax considered as a good electrical insulator. Results obtained show that, using of MEPCM suspension instead of pure transformer oil lead to improve the cooling performance of transformer by reducing its temperature and as a consequence increasing its protection against the breakdown. The melting fraction increased with increasing outside temperature up to certain temperature after which the melting fraction reach maximum constant value (MF = 1 which indicate that, the choosing of PCM depend on the environment in which the transformer is used.

  2. Influence of molybdenum content on transformation behavior of high performance bridge steel during continuous cooling

    International Nuclear Information System (INIS)

    Chen, Jun; Tang, Shuai; Liu, Zhenyu; Wang, Guodong

    2013-01-01

    Highlights: ► The bainite transformation field was refined. ► The empirical equation to estimate the GF s was established. ► Transformation behavior was studied with serially increasing Mo addition. ► The molybdenum content can be lowered as the cooling rate is increased. ► GF transformation field is also shifted to right by increasing Mo content. - Abstract: The continuous-cooling-transformation (CCT) diagrams of high performance bridge steel with different molybdenum content were plotted by means of a combined method of dilatometry and metallography. The results show that the molybdenum addition of 0.17 wt% does not noticeably alter the transformation behavior, whereas 0.38 wt% significantly. In addition, the molybdenum addition of 0.38 wt% completely eliminates the formation of polygonal ferrite (PF) and significantly lower the granular ferrite (GF) transformation starting temperatures throughout the range of cooling rates studied. At lower cooling rates, with the increase of the molybdenum content, the martensite/austenite (M/A) constituents are noticeably refined, whereas the effects are not obvious at higher cooling rates. Moreover, the molybdenum addition of 0.38 wt% can significantly increase the Vickers hardness, but the Vickers hardness increments (by comparison of Mo-0.17wt% steel and Mo-0.38wt% steel) are sharply reduced at the cooling rate of 30 °C/s, indicating that at higher cooling rate, the molybdenum usage can be saved and the higher strengthen can be also gained. It could be found the GF transformation starting temperature is linear with the cooling rate. The empirical equation was established to calculate GF transformation starting temperatures, and the calculated values are in good agreement with measured ones

  3. Statistical multi-model approach for performance assessment of cooling tower

    International Nuclear Information System (INIS)

    Pan, Tian-Hong; Shieh, Shyan-Shu; Jang, Shi-Shang; Tseng, Wen-Hung; Wu, Chan-Wei; Ou, Jenq-Jang

    2011-01-01

    This paper presents a data-driven model-based assessment strategy to investigate the performance of a cooling tower. In order to achieve this objective, the operations of a cooling tower are first characterized using a data-driven method, multiple models, which presents a set of local models in the format of linear equations. Satisfactory fuzzy c-mean clustering algorithm is used to classify operating data into several groups to build local models. The developed models are then applied to predict the performance of the system based on design input parameters provided by the manufacturer. The tower characteristics are also investigated using the proposed models via the effects of the water/air flow ratio. The predicted results tend to agree well with the calculated tower characteristics using actual measured operating data from an industrial plant. By comparison with the design characteristic curve provided by the manufacturer, the effectiveness of cooling tower can be obtained in the end. A case study conducted in a commercial plant demonstrates the validity of proposed approach. It should be noted that this is the first attempt to assess the cooling efficiency which is deviated from the original design value using operating data for an industrial scale process. Moreover, the evaluated process need not interrupt the normal operation of the cooling tower. This should be of particular interest in industrial applications.

  4. Pathways to Health Risk Exposure in Adult Film Performers

    OpenAIRE

    Grudzen, Corita R.; Ryan, Gery; Margold, William; Torres, Jacqueline; Gelberg, Lillian

    2008-01-01

    Despite being part of a large and legal industry in Los Angeles, little is known about adult film performers’ exposure to health risks and when and how these risks might occur. The objective was to identify exposure to physical, mental, and social health risks and the pathways to such risks among adult film performers and to determine how risks differ between different types of performers, such as men and women. Semi-structured in-depth interviews were conducted with 18 female and ten male pe...

  5. Effect of Perovskite Film Preparation on Performance of Solar Cells

    Directory of Open Access Journals (Sweden)

    Yaxian Pei

    2016-01-01

    Full Text Available For the perovskite solar cells (PSCs, the performance of the PSCs has become the focus of the research by improving the crystallization and morphology of the perovskite absorption layer. In this thesis, based on the structure of mesoporous perovskite solar cells (MPSCs, we designed the experiments to improve the photovoltaic performance of the PSCs by improved processing technique, which mainly includes the following two aspects. Before spin-coating PbI2 solution, we control the substrate temperature to modify the crystal quality and morphology of perovskite films. On the other hand, before annealing, we keep PbI2 films for the different drying time at room temperature to optimize films morphology. In our trials, it was found that the substrate temperature is more important in determining the photovoltaic performance than drying time. These results indicate that the crystallization and morphology of perovskite films affect the absorption intensity and obviously influence the short circuit current density of MPSCs. Utilizing films prepared by mentioning two methods, MPSCs with maximum power conversion efficiency of over 4% were fabricated for the active area of 0.5 × 0.5 cm2.

  6. Large Eddy Simulation of a Film Cooling Flow Injected from an Inclined Discrete Cylindrical Hole into a Crossflow with Zero-Pressure Gradient Turbulent Boundary Layer

    Science.gov (United States)

    Johnson, Perry L.; Shyam, Vikram

    2012-01-01

    A Large Eddy Simulation (LES) is performed of a high blowing ratio (M = 1.7) film cooling flow with density ratio of unity. Mean results are compared with experimental data to show the degree of fidelity achieved in the simulation. While the trends in the LES prediction are a noticeable improvement over Reynolds-Averaged Navier-Stokes (RANS) predictions, there is still a lack a spreading on the underside of the lifted jet. This is likely due to the inability of the LES to capture the full range of influential eddies on the underside of the jet due to their smaller structure. The unsteady structures in the turbulent coolant jet are also explored and related to turbulent mixing characteristics

  7. Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films.

    Science.gov (United States)

    Park, Jun-Sik; Kim, Dug-Joong; Chung, Wan-Ho; Lim, Yonghyun; Kim, Hak-Sung; Kim, Young-Beom

    2017-09-29

    Here we report a photonic annealing process for yttria-stabilized zirconia films, which are one of the most well-known solid-state electrolytes for solid oxide fuel cells (SOFCs). Precursor films were coated using a wet-chemical method with a simple metal-organic precursor solution and directly annealed at standard pressure and temperature by two cycles of xenon flash lamp irradiation. The residual organics were almost completely decomposed in the first pre-annealing step, and the fluorite crystalline phases and good ionic conductivity were developed during the second annealing step. These films showed properties comparable to those of thermally annealed films. This process is much faster than conventional annealing processes (e.g. halogen furnaces); a few seconds compared to tens of hours, respectively. The significance of this work includes the treatment of solid-state electrolyte oxides for SOFCs and the demonstration of the feasibility of other oxide components for solid-state energy devices.

  8. What makes gambling cool? Images of agency and self-control in fiction films.

    Science.gov (United States)

    Egerer, Michael; Rantala, Varpu

    2015-03-01

    The study is a qualitative film analysis. It seeks to determine the semiotic and cinematic structures that make gambling appealing in films based on analysis of 72 film scenes from 28 narrative fiction films made from 1922 to 2003 about gambling in North American and West European mainstream cinema. The main game types include card games, casino games, and slot machines. The theme of self-control and competence was identified as being central to gambling's appeal. These images are strongly defined by gender. The study was funded by ELOMEDIA, financed by the Finnish Ministry of Education and Culture as well as the Finnish Foundation for Alcohol Studies. The limitations of the study are noted.

  9. Preliminary tests of a model of cooling-pond thermal performance

    International Nuclear Information System (INIS)

    Hicks, B.B.; Wesely, M.L.; Wilczek, J.

    1975-01-01

    Experiments performed during recent years at the cooling pond complex at the Dresden nuclear power station have been designed to improve our understanding of the fundamental properties of thermal exchange at a warm-water surface. To a considerable extent, the field studies have been successful in that they have shown that modern micrometeorological techniques can be successfully applied to the demanding circumstances of an industrial cooling lake at temperature of at least 40 0 C. The intent of these studies has been to create a set of parameterization schemes good enough to allow simulation of the performance of the Dresden cooling lake without adjustment of numerical constants. An obvious extension of these studies, and one of the goals of the cooling-pond research program as presently stated, is to obtain an accurate numerical simulation of thermal performance of ponds with use of the improved formulations that have resulted from the experimental work at the Dresden lake. The computer model is divided into two sections and can be used to test the sensitivity of predicted performance to variations in procedures for determining the thermal transfer from the surface

  10. Internal film cooling of permanent magnet external rotor machine using the example of a small wind power generator; Innenkuehlung permanentmagneterregter Aussenlaeufermaschinen am Beispiel eines Kleinwindenergiegenerators

    Energy Technology Data Exchange (ETDEWEB)

    Miersch, Soeren; Eckart, Martin; Michalke, Norbert [HTW Dresden (Germany)

    2011-07-01

    This article discusses the fluid flow and thermal cooling system design of a permanent magnet small wind power generator in external rotor construction. Analytical calculation attachment pieces and numerical simulations will be served as authoring tool. Calculation and simulation results will be exhibited in comparing with model and prototype measurements. With the help of stationary temperature allocation, the effectiveness of intensive internal film cooling will be shown. (orig.)

  11. Improving the performance of power-limited transverse stochastic cooling systems

    International Nuclear Information System (INIS)

    Goldberg, D.A.; Lambertson, G.R.

    1989-08-01

    We present the formulas relevant to the behavior of (transverse) stochastic cooling systems which operate under the not uncommon condition that performance is limited by available output power, and contrast the operation of such systems with non-power-limited ones. In particular, we show that for power-limited systems, the two most effective improvements are the use of pickups/kickers which operate in both planes simultaneously and/or plunging of the cooling system electrodes, and present an example where increasing bandwidth is counter-productive. We apply our results to the proposed upgrade of the Fermilab bar p source. 4 refs., 1 fig., 2 tabs

  12. Corrosion resistance of high performance stainless steels in cooling water and other refinery environments

    International Nuclear Information System (INIS)

    Kovach, C.W.; Redmerski, L.S.

    1984-01-01

    The recent successful introduction of high performance stainless steels as tubing for seawater cooled electric utility condensers suggests that these alloys can also provide useful service in refinery heat exchanger applications. Since many of these applications involve higher temperature exposure than steam condensers, a study was conducted to evaluate crevice corrsion resistance over a range of cooling water temperature and chloride concentrations, and also to evaluate general corrosion resistance in some strong chemical and refinery environments. These stainless steels display excellent crevice corrosion resistance as well as good resistance to a variety of chemical environments that may be encountered in refinery, petrochemical and chemical plant service

  13. Sensitivity analysis of the thermal performance of radiant and convective terminals for cooling buildings

    DEFF Research Database (Denmark)

    Le Dréau, J.; Heiselberg, P.

    2014-01-01

    Heating and cooling terminals can be classified in two main categories: convective terminals (e.g. active chilled beam, air conditioning) and radiant terminals. The mode of heat transfer of the two emitters is different: the first one is mainly based on convection, whereas the second one is based...... conducted to determine the parameters influencing their thermal performance the most. The air change rate, the outdoor temperature and the air temperature stratification have the largest effect on the cooling need (maintaining a constant operative temperature). For air change rates higher than 0.5 ACH...

  14. Relating hydrogen-bonding interactions with the phase behavior of naproxen/PVP K 25 solid dispersions: evaluation of solution-cast and quench-cooled films.

    Science.gov (United States)

    Paudel, Amrit; Nies, Erik; Van den Mooter, Guy

    2012-11-05

    In this work, we investigated the relationship between various intermolecular hydrogen-bonding (H-bonding) interactions and the miscibility of the model hydrophobic drug naproxen with the hydrophilic polymer polyvinylpyrrolidone (PVP) across an entire composition range of solid dispersions prepared by quasi-equilibrium film casting and nonequilibrium melt quench cooling. The binary phase behavior in solid dispersions exhibited substantial processing method dependence. The solid state solubility of crystalline naproxen in PVP to form amorphous solid dispersions was 35% and 70% w/w naproxen in solution-cast films and quench-cooled films, respectively. However, the presence of a single mixed phase glass transition indicated the amorphous miscibility to be 20% w/w naproxen for the films, beyond which amorphous-amorphous and/or crystalline phase separations were apparent. This was further supported by the solution state interactions data such as PVP globular size distribution and solution infrared spectral profiles. The borderline melt composition showed cooling rate dependence of amorphization. The glass transition and melting point depression profiles of the system were treated with the analytical expressions based on Flory-Huggins mixing theory to interpolate the equilibrium solid solubility. FTIR analysis and subsequent spectral deconvolution revealed composition and miscibility dependent variations in the strength of drug-polymer intermolecular H-bonding. Two types of H-bonded populations were evidenced from 25% w/w and 35% w/w naproxen in solution-cast films and quench-cooled films, respectively, with the higher fraction of strongly H-bonded population in the drug rich domains of phase separated amorphous film compositions and highly drug loaded amorphous quench-cooled dispersions.

  15. Annealing effects on room temperature thermoelectric performance of p-type thermally evaporated Bi-Sb-Te thin films

    Science.gov (United States)

    Singh, Sukhdeep; Singh, Janpreet; Tripathi, S. K.

    2018-05-01

    Bismuth antimony telluride (Bi-Sb-Te) compounds have been investigated for the past many decades for thermoelectric (TE) power generation and cooling purpose. We synthesized this compound with a stoichiometry Bi1.2Sb0.8Te3 through melt cool technique and thin films of as synthesized material were deposited by thermal evaporation. The prime focus of the present work is to study the influence of annealing temperature on the room temperature (RT) power factor of thin films. Electrical conductivity and Seebeck coefficient were studied and power factors were calculated which showed a peak value at 323 K. The compounds performance is comparable to some very efficient Bi-Sb-Te reported stoichiometries at RT scale. The values observed show that material has an enormous potential for energy production at ambient temperature scales.

  16. Effect of air condition on AP-1000 containment cooling performance in station black out accident

    International Nuclear Information System (INIS)

    Hendro Tjahjono

    2015-01-01

    AP1000 reactor is a nuclear power plant generation III+ 1000 MWe which apply passive cooling concept to anticipate accidents triggered by the extinction of the entire supply of electrical power or Station Black Out (SBO). In the AP1000 reactor, decay heat disposal mechanism conducted passively through the PRHR-IRWST and subsequently forwarded to the reactor containment. Containment externally cooled through natural convection in the air gap and through evaporation cooling water poured on the outer surface of the containment wall. The mechanism of evaporation of water into the air outside is strongly influenced by the conditions of humidity and air temperature. The purpose of this study was to determine the extent of the influence of the air condition on cooling capabilities of the AP1000 containment. The method used is to perform simulations using Matlab-based analytical calculation model capable of estimating the power of heat transferred. The simulation results showed a decrease in power up to 5% for relative humidity rose from 10% to 95%, while the variation of air temperature of 10°C to 40°C, the power will decrease up to 15%. It can be concluded that the effect of air temperature increase is much more significant in lowering the containment cooling ability compared with the increase of humidity. (author)

  17. Design optimization of electric vehicle battery cooling plates for thermal performance

    Science.gov (United States)

    Jarrett, Anthony; Kim, Il Yong

    The performance of high-energy battery cells utilized in electric vehicles (EVs) is greatly improved by adequate temperature control. An efficient thermal management system is also desirable to avoid diverting excessive power from the primary vehicle functions. In a battery cell stack, cooling can be provided by including cooling plates: thin metal fabrications which include one or more internal channels through which a coolant is pumped. Heat is conducted from the battery cells into the cooling plate, and transported away by the coolant. The operating characteristics of the cooling plate are determined in part by the geometry of the channel; its route, width, length, etc. In this study, a serpentine-channel cooling plate is modeled parametrically and its characteristics assessed using computational fluid dynamics (CFD). Objective functions of pressure drop, average temperature, and temperature uniformity are defined and numerical optimization is carried out by allowing the channel width and position to vary. The optimization results indicate that a single design can satisfy both pressure and average temperature objectives, but at the expense of temperature uniformity.

  18. Performance evaluation of radiant cooling system application on a university building in Indonesia

    Science.gov (United States)

    Satrio, Pujo; Sholahudin, S.; Nasruddin

    2017-03-01

    The paper describes a study developed to estimate the energy savings potential of a radiant cooling system installed in an institutional building in Indonesia. The simulations were carried out using IESVE to evaluate thermal performance and energy consumption The building model was calibrated using the measured data for the installed radiant system. Then this calibrated model was used to simulate the energy consumption and temperature distribution to determine the proportional energy savings and occupant comfort under different systems. The result was radiant cooling which integrated with a Dedicated Outside Air System (DOAS) could make 41,84% energy savings compared to the installed cooling system. The Computational Fluid Dynamics (CFD) simulation showed that a radiant system integrated with DOAS provides superior human comfort than a radiant system integrated with Variable Air Volume (VAV). Percentage People Dissatisfied was kept below 10% using the proposed system.

  19. Influence of Cooling Condition on the Performance of Grinding Hardened Layer in Grind-hardening

    Science.gov (United States)

    Wang, G. C.; Chen, J.; Xu, G. Y.; Li, X.

    2018-02-01

    45# steel was grinded and hardened on a surface grinding machine to study the effect of three different cooling media, including emulsion, dry air and liquid nitrogen, on the microstructure and properties of the hardened layer. The results show that the microstructure of material surface hardened with emulsion is pearlite and no hardened layer. The surface roughness is small and the residual stress is compressive stress. With cooling condition of liquid nitrogen and dry air, the specimen surface are hardened, the organization is martensite, the surface roughness is also not changed, but high hardness of hardened layer and surface compressive stress were obtained when grinding using liquid nitrogen. The deeper hardened layer grinded with dry air was obtained and surface residual stress is tensile stress. This study provides an experimental basis for choosing the appropriate cooling mode to effectively control the performance of grinding hardened layer.

  20. Experimental Flow Performance Evaluation of novel miniaturized Advanced Piezoelectric Dual Cooling Jet

    International Nuclear Information System (INIS)

    De Bock, H P J; Whalen, B P; Chamarthy, P; Jackson, J L

    2012-01-01

    In recent years, electronics systems have significantly reduced in size at maintained or increased functionality. This trend has led to an increased demand for smaller and more capable thermal management. However, miniaturization of conventional fan and heat sink cooling systems introduce significant size, weight and efficiency challenges. In this study the flow performance of a novel alternative thin form-factor cooling solution, the advanced piezoelectric dual cooling jet(DCJ), is evaluated. A DCJ is a system where two piezoelectric actuators are excited to produce air flow. The total height of the device is about 1mm. The design of the experimental method for evaluating the equivalent fan-curve of the DCJ device is described in detail. Experimental results in comparison to conventional fan solutions are provided. The DCJ is expected to be a good candidate for thermal management in next generation thin profile consumer electronics.

  1. Prediction of the Long Term Cooling Performance for the 3-Pin Fuel Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. K.; Chi, D. Y.; Sim, B. S.; Park, K. N.; Ahn, S. H.; Lee, J. M.; Lee, C. Y.; Kim, H. R

    2005-12-15

    In the long term cooling phase that the emergency cooling water injection ends, the performance of the residual heat removal for the 3-pin fuel test loop has been predicted by a simplified heat transfer model. In the long term cooling phase the residual heat is 1323W for PWR fuel test mode and 1449W for CANDU fuel test mode. The each residual heat is assumed as 2% of the fission power of the test fuel used in the anticipated operational occurrence and design basis accident analyses. The each fission power used for the analyses is 105% of the rated fission power in the normal operation. In the long term cooling phase the residual heat is removed to the HANARO pool through the double pressure vessels of the in-pile test section. Saturate pooling boiling is assumed on the test fuel and condensation heat transfer is expected on the inner wall of the fuel carrier and the flow divider. Natural convection heat transfer on a heated vertical wall is also assumed on the outer wall of the outer pressure vessel. The conduction heat transfer is only considered in the gap between the double pressure vessels charged with neon gas and in the downcomer filled with coolant. The heat transfer rate between the coolant temperature of 152 .deg. C in the in-pile test section and the water temperature of 45 .deg. C in the HANARO pool is predicted as about 1666W. The 152 .deg. C is the saturate temperature of the coolant pressure predicted from the MARS code. The cooling capacity of 1666W is greater than the residual heats of 1323W and 1449W. Consequently the long term cooling performance of the 3-pin fuel test loop is sufficient for the anticipated operational occurrences and design basis accidents.

  2. Assessment of cooling performance of a diffuse plate in HYPER target

    International Nuclear Information System (INIS)

    Tak, N. I.; Song, T. Y.; Park, W. S.

    2001-01-01

    Major difficulties are caused by cooling problems of the beam window of the spallation target in designing of 1000 MWth HYPER (HYbrid Power Extraction Reactor). Numerical studies to improve the cooling capability of the window are on the way. In the present work, numerical analysis has been performed to assess the cooling performance of a diffuse plate in HYPER target conditions. The fluid dynamics code CFX 4 was used for the analysis. Heat depositions in the window and the target were calculated by the LAHEAT code systems and used as input data of the CFX 4 code. The diffuse plate was modeled as a porous media having three porosities. The analysis was performed for various design parameters (the porosity, the thickness of a diffuse plate, the distance between the plate and the window). The results of CFX 4 show that ∼10 .deg. C of the reduction of the maximum window temperature, which is not enough for the HYPER design, can be obtained with a diffuse plate. Therefore, another methods such as an introduction of a bypass injection have to be considered to improve the window cooling

  3. Aligned Carbon Nanotubes for High-Performance Films and Composites

    Science.gov (United States)

    Zhang, Liwen

    Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or

  4. Assessment of the effect of nitrogen gas on passive containment cooling system performance

    International Nuclear Information System (INIS)

    Ha, Huiun; Suh, Jungsoo

    2016-01-01

    As a part of the passive containment cooling system (PCCS) of Innovative PWR development project, we have been investigating the effect of the nitrogen gas released from safety injection tank (SIT) on PCCS performance. With the design characteristics of APR1400 and conceptual design of PCCS, we developed a GOTHIC model of the APR1400 containment with PCCS. The calculation model is described herein, and representative results from the calculation are presented as well. The results of the present work will be used for the design of PCCS. APR1400 GOTHIC model was developed for assessment on the effect of SIT nitrogen gas on passive containment cooling system performance. Calculation results confirmed that influence of nitrogen gas release is negligible; however, further studies should be performed to confirm effect of non-condensable gas on the final performance of PCCS. These insights are important for developing the PCCS of Innovative PWR

  5. Assessment of the effect of nitrogen gas on passive containment cooling system performance

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Huiun; Suh, Jungsoo [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    As a part of the passive containment cooling system (PCCS) of Innovative PWR development project, we have been investigating the effect of the nitrogen gas released from safety injection tank (SIT) on PCCS performance. With the design characteristics of APR1400 and conceptual design of PCCS, we developed a GOTHIC model of the APR1400 containment with PCCS. The calculation model is described herein, and representative results from the calculation are presented as well. The results of the present work will be used for the design of PCCS. APR1400 GOTHIC model was developed for assessment on the effect of SIT nitrogen gas on passive containment cooling system performance. Calculation results confirmed that influence of nitrogen gas release is negligible; however, further studies should be performed to confirm effect of non-condensable gas on the final performance of PCCS. These insights are important for developing the PCCS of Innovative PWR.

  6. Low-temperature enhancement of plasmonic performance in silver films

    Czech Academy of Sciences Publication Activity Database

    Jayanti, S.V.; Park, J.H.; Dejneka, Alexandr; Chvostová, Dagmar; McPeak, K.M.; Chen, X.; Oh, S.H.; Norris, D.J.

    2015-01-01

    Roč. 5, č. 5 (2015), 1147-1155 ISSN 2159-3930 R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:68378271 Keywords : plasmonic performance * silver films * low temperature * spectroscopic ellipsometry Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.657, year: 2015

  7. Experimental and numerical performance analysis of a converging channel heat exchanger for PV cooling

    International Nuclear Information System (INIS)

    Baloch, Ahmer A.B.; Bahaidarah, Haitham M.S.; Gandhidasan, Palanichamy; Al-Sulaiman, Fahad A.

    2015-01-01

    Highlights: • Effect of varying converging angle on temperature characteristics of PV surface studied. • Optical, CFD, thermal, and electrical models developed for the analysis. • Experimental measurements carried out for two configurations for June and December. • Using this cooling technique, maximum cell temperature reduction was 57.8%. • Maximum percentage improvement in power output was 35.5%. - Abstract: An experimental and numerical investigation of a cooling technique called as converging channel cooling intended to achieve low and uniform temperature on the surface of PV panel is presented in this paper. Experimental evaluation for an uncooled PV system and a converging channel cooled PV system was carried out subjected to the hot climate of Saudi Arabia for the month of June and December. Detailed modeling was performed using numerical analysis to investigate the effect of changing the converging angle on the thermal characteristics of the PV system. Based on the developed model, two degrees angle showed the best performance in terms of temperature distribution and average cell temperature with a standard deviation of 0.91 °C. A comprehensive system model was developed to assess the performance of PV systems numerically by coupling the optical, radiation, thermal, computational fluid dynamics, and electrical model. Thermal measurements for an uncooled PV showed cell temperature as high as 71.2 °C and 48.3 °C for the month of June and December, respectively. By employing converging cooling, cell temperature was reduced significantly to 45.1 °C for June and to 36.4 °C for December. Maximum percentage improvement in power output was 35.5% whereas maximum percentage increase in the conversion efficiency was 36.1% when compared to the performance of an uncooled PV system. For cost feasibility of an uncooled and cooled PV system, levelized cost of energy (LCE) analysis was performed using the annual energy yield simulation for both systems. LCE

  8. Development and Performance of an Advanced Ejector Cooling System for a Sustainable Built Environment

    Directory of Open Access Journals (Sweden)

    Paulo ePereira

    2015-06-01

    Full Text Available Ejector refrigeration is a promising technology for the integration into solar driven cooling systems because of its relative simplicity and low initial cost. The major drawback of such a system is associated to its relatively low coefficient of performance (COP under variable operating conditions. In order to overcome this problem, an advanced ejector was developed that changes its geometrical features depending on the upstream and downstream conditions. This paper provides a short overview of the development process and results of a small cooling capacity (1.5 kW solar driven cooling system using a variable geometry ejector. During the design steps, a number of theoretical works have been carried out, including the selection of the working fluid, the determination of the geometrical requirements and prototype design. Based on the analysis, R600a was selected as working fluid. A prototype was constructed with two independent variable geometrical factors: the area ratio and the nozzle exit position. A test rig was also assembled in order to test the ejector performance under controlled laboratory conditions and to elaborate a control algorithm for the variable geometry. Ejector performance was assessed by calculation of cooling cycle COP, entrainment ratio and critical back pressure. The results show that for a condenser pressure of 3 bar, an 80% increase in the COP was obtained when compared to the performance of a fixed geometry ejector. Experimental COP values varied between 0.4 and 0.8, depending on operating conditions. Currently the cooling cycle is being integrated into a solar driven demonstration site for long term in situ assessment.

  9. Experimental Study of the Cooling of Electrical Components Using Water Film Evaporation

    Directory of Open Access Journals (Sweden)

    S. Harmand

    2012-01-01

    Full Text Available Heat and mass transfer, which occur in the evaporation of a falling film of water, are studied experimentally. This evaporation allows the dissipation of the heat flux produced by twelve resistors, which simulate electrical components on the back side of an aluminium plate. On the front side of the plate, a falling film of water flows by the action of gravity. An inverse heat conduction model, associated with a spatial regularisation, was developed and produces the local heat fluxes on the plate using the measured temperatures. The efficiency of this evaporative process has been studied with respect to several parameters: imposed heat flux, inlet mass flow rate, and geometry. A comparison of the latent and sensible fluxes used to dissipate the imposed heat flux was studied in the case of a plexiglass sheet in front of the falling film at different distances from the aluminium plate.

  10. Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films

    OpenAIRE

    Park, Jun-Sik; Kim, Dug-Joong; Chung, Wan-Ho; Lim, Yonghyun; Kim, Hak-Sung; Kim, Young-Beom

    2017-01-01

    Here we report a photonic annealing process for yttria-stabilized zirconia films, which are one of the most well-known solid-state electrolytes for solid oxide fuel cells (SOFCs). Precursor films were coated using a wet-chemical method with a simple metal-organic precursor solution and directly annealed at standard pressure and temperature by two cycles of xenon flash lamp irradiation. The residual organics were almost completely decomposed in the first pre-annealing step, and the fluorite cr...

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

    International Nuclear Information System (INIS)

    Mongkon, S.; Thepa, S.; Namprakai, P.; Pratinthong, N.

    2014-01-01

    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 m 2 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

  12. Performative building envelope design correlated to solar radiation and cooling energy consumption

    Science.gov (United States)

    Jacky, Thiodore; Santoni

    2017-11-01

    Climate change as an ongoing anthropogenic environmental challenge is predominantly caused by an amplification in the amount of greenhouse gases (GHGs), notably carbon dioxide (CO2) in building sector. Global CO2 emissions are emitted from HVAC (Heating, Ventilation, and Air Conditioning) occupation to provide thermal comfort in building. In fact, the amount of energy used for cooling or heating building is implication of building envelope design. Building envelope acts as interface layer of heat transfer between outdoor environment and the interior of a building. It appears as wall, window, roof and external shading device. This paper examines performance of various design strategy on building envelope to limit solar radiation and reduce cooling loads in tropical climate. The design strategies are considering orientation, window to wall ratio, material properties, and external shading device. This research applied simulation method using Autodesk Ecotect to investigate simultaneously between variations of wall and window ratio, shading device composition and the implication to the amount of solar radiation, cooling energy consumption. Comparative analysis on the data will determine logical variation between opening and shading device composition and cooling energy consumption. Optimizing the building envelope design is crucial strategy for reducing CO2 emissions and long-term energy reduction in building sector. Simulation technology as feedback loop will lead to better performative building envelope.

  13. An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling

    International Nuclear Information System (INIS)

    Ozgener, Leyla; Ozgener, Onder

    2010-01-01

    The present study highlights the exergetic performance characteristics of an underground air tunnel for greenhouse cooling with a 47 m horizontal, 56 cm nominal diameter U-bend buried galvanized ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Underground air tunnel systems, also known as earth-to-air heat exchangers, are recognized to be outstanding heating, cooling and air heating systems. On the other hand, they have not been used yet in the Turkish market. Greenhouses also have important economical potential in Turkey's agricultural sector. Greenhouses should be cooled during the summer or hot days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of underground air tunnels with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future. The exergy transports between the components and the destructions in each of the components of the system are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The daily maximum cooling coefficient of performances (COP) values for the system are also obtained to be 15.8. The total average COP in the experimental period is found to be 10.09. The system COP was calculated based on the amount of cooling produced by the air tunnel and the amount of power required to move the air through the tunnel, while the exergetic efficiency of the air tunnel is found to be in a range among 57.8-63.2%. The overall exergy efficiency value for the system on a product/fuel basis is found to be 60.7%. (author)

  14. Turbine Internal and Film Cooling Modeling For 3D Navier-Stokes Codes

    Science.gov (United States)

    DeWitt, Kenneth; Garg Vijay; Ameri, Ali

    2005-01-01

    The aim of this research project is to make use of NASA Glenn on-site computational facilities in order to develop, validate and apply aerodynamic, heat transfer, and turbine cooling models for use in advanced 3D Navier-Stokes Computational Fluid Dynamics (CFD) codes such as the Glenn-" code. Specific areas of effort include: Application of the Glenn-HT code to specific configurations made available under Turbine Based Combined Cycle (TBCC), and Ultra Efficient Engine Technology (UEET) projects. Validating the use of a multi-block code for the time accurate computation of the detailed flow and heat transfer of cooled turbine airfoils. The goal of the current research is to improve the predictive ability of the Glenn-HT code. This will enable one to design more efficient turbine components for both aviation and power generation. The models will be tested against specific configurations provided by NASA Glenn.

  15. Performance study of ejector cooling cycle at critical mode under superheated primary flow

    International Nuclear Information System (INIS)

    Tashtoush, Bourhan; Alshare, Aiman; Al-Rifai, Saja

    2015-01-01

    Highlights: • The ECC is modeled using EES Software and it is validated with published data. • Detailed analysis of the ECC with different refrigerants is conducted. • The constant pressure mixing is better than constant area mixing ejectors. • R134a is the selected refrigerant for the best cooling cycle performance. • The superheated primary flow at critical mode is achieved with EJ2 ejector used. - Abstract: In this work the performance of the ejector cooling cycle is investigated at critical mode, where, the effects of ejector geometry, refrigerant type, and operating condition are studied. The ejector cooling cycle is modeled with EES Software. The mass, momentum, and energy conservation principles are applied to the secondary and primary flows to investigate the performance of the ejector cooling cycle under superheated primary flow. The refrigerant R134 a is selected based on the merit of its environmental and performance characteristics. The primary working fluid in the refrigeration cycle is maintained at superheated conditions for optimal ejector performance. The solar generator temperature ranges are 80–100 °C. The operating temperature of evaporator range is 8–12 °C and the optimal condensation temperature is in the range of 28–40 °C. It is found that constant-pressure mixing ejector generates higher backpressure than constant-area mixing ejector for the same entrainment ratio and COP. The type of ejector is selected based on the performance criteria of the critical backpressure and choking condition of the primary flow, the so called EJ2 type ejector meets the criteria. The COP is found to be in the range of 0.59–0.67 at condenser backpressure of 24 bar due to higher critical condenser pressure and higher generator temperature

  16. Experimental study of the influence of atmospheric conditions on the performance of natural draft dry cooling towers

    International Nuclear Information System (INIS)

    Markoczy, G.; Staempfli, E.

    1977-08-01

    The heat dissipation of cooling towers is influenced by atmospheric conditions. In order to establish these influences EIR conducted measurements on a natural draft dry cooling tower. During two measuring campaigns with a duration of total 10 weeks the performance of the cooling tower, the ambient air temperatures, the wind velocities and directions as well as air temperature at the top of the tower and in front of the heat exchangers were continuously measured and registered. The results achieved enable the quantitative description of the influence of the ambient air temperature, wind and temperature inversion on the performance of natural draft dry cooling towers. (Auth.)

  17. Performance investigation of solid desiccant evaporative cooling system configurations in different climatic zones

    International Nuclear Information System (INIS)

    Ali, Muzaffar; Vukovic, Vladimir; Sheikh, Nadeem Ahmed; Ali, Hafiz M.

    2015-01-01

    Highlights: • Five configurations of a DEC system are analyzed in five climate zones. • DEC system model configurations are developed in Dymola/Modelica. • Performance analysis predicted a suitable DEC system configuration for each climate zone. • Results show that climate of Vienna, Sao Paulo, and Adelaide favors the ventilated-dunkle cycle. • While ventilation cycle configuration suits the climate of Karachi and Shanghai. - Abstract: Performance of desiccant evaporative cooling (DEC) system configurations is strongly influenced by the climate conditions and varies widely in different climate zones. Finding the optimal configuration of DEC systems for a specific climatic zone is tedious and time consuming. This investigation conducts performance analysis of five DEC system configurations under climatic conditions of five cities from different zones: Vienna, Karachi, Sao Paulo, Shanghai, and Adelaide. On the basis of operating cycle, three standard and two modified system configurations (ventilation, recirculation, dunkle cycles; ventilated-recirculation and ventilated-dunkle cycles) are analyzed in these five climate zones. Using an advance equation-based object-oriented (EOO) modeling and simulation approach, optimal configurations of a DEC system are determined for each climate zone. Based on the hourly climate data of each zone for its respective design cooling day, performance of each system configuration is estimated using three performance parameters: cooling capacity, COP, and cooling energy delivered. The results revealed that the continental/micro-thermal climate of Vienna, temperate/mesothermal climate of Sao Paulo, and dry-summer subtropical climate of Adelaide favor the use of ventilated-dunkle cycle configuration with average COP of 0.405, 0.89 and 1.01 respectively. While ventilation cycle based DEC configuration suits arid and semiarid climate of Karachi and another category of temperate/mesothermal climate of Shanghai with average COP of

  18. Reassessment of debris ingestion effects on emergency core cooling-system pump performance

    International Nuclear Information System (INIS)

    Sciacca, F.W.; Rao, D.V.

    2004-01-01

    A study sponsored by the United States (US) Nuclear Regulatory Commission (NRC) was performed to reassess the effects of ingesting loss of coolant accident (LOCA) generated materials into emergency core cooling system (ECCS) pumps and the subsequent impact of this debris on the pumps' ability to provide long-term cooling to the reactor core. ECCS intake systems have been designed to screen out large post-LOCA debris materials. However, small-sized debris can penetrate these intake strainers or screens and reach critical pump components. Prior NRC-sponsored evaluations of possible debris and gas ingestion into ECCS pumps and attendant impacts on pump performance were performed in the early 1980's. The earlier study focused primarily on pressurised water reactor (PWR) ECCS pumps. This issue was revisited both to factor in our improved knowledge of LOCA generated debris and to address specifically both boiling water reactor (BWR) and PWR ECCS pumps. This study discusses the potential effects of ingested debris on pump seals, bearing assemblies, cyclone debris separators, and seal cooling water subsystems. This assessment included both near-term (less than one hour) and long-term (greater than one hour) effects introduced by the postulated LOCA. The work reported herein was performed during 1996-1997. (authors)

  19. Effect of turbulence intensity on cross-injection film cooling at a stepped or smooth endwall of a gas turbine vane passage.

    Science.gov (United States)

    Wu, Pey-Shey; Tsai, Shen-Ta; Jhuo, Yue-Hua

    2014-01-01

    This study is concerned with a film cooling technique applicable to the protection of the endwalls of a gas turbine vane. In the experiments, cross-injection coolant flow from two-row, paired, inclined holes with nonintersecting centerlines was utilized. The test model is a scaled two-half vane. The levels of turbulence intensity used in the experiments are T.I. = 1.8%, 7%, and 12%. Other parameters considered in the film cooling experiments include three inlet Reynolds numbers (9.20 × 10(4), 1.24 × 10(5), and 1.50 × 10(5)), three blowing ratios (0.5, 1.0, and 2.0), and three endwall conditions (smooth endwall and stepped endwall with forward-facing or backward-facing step). Thermochromic liquid crystal (TLC) technique with steady-state heat transfer experiments was used to obtain the whole-field film cooling effectiveness. Results show that, at low turbulence intensity, increasing Reynolds number decreases the effectiveness in most of the vane passage. There is no monotonic trend of influence by Reynolds number at high turbulence intensity. The effect of blowing ratio on the effectiveness has opposite trends at low and high turbulence levels. Increasing turbulent intensity decreases the effectiveness, especially near the inlet of the vane passage. With a stepped endwall, turbulence intensity has only mild effect on the film cooling effectiveness.

  20. Effect of Turbulence Intensity on Cross-Injection Film Cooling at a Stepped or Smooth Endwall of a Gas Turbine Vane Passage

    Directory of Open Access Journals (Sweden)

    Pey-Shey Wu

    2014-01-01

    Full Text Available This study is concerned with a film cooling technique applicable to the protection of the endwalls of a gas turbine vane. In the experiments, cross-injection coolant flow from two-row, paired, inclined holes with nonintersecting centerlines was utilized. The test model is a scaled two-half vane. The levels of turbulence intensity used in the experiments are T.I.=1.8%, 7%, and 12%. Other parameters considered in the film cooling experiments include three inlet Reynolds numbers (9.20×104 , 1.24×105, and  1.50×105, three blowing ratios (0.5, 1.0, and 2.0, and three endwall conditions (smooth endwall and stepped endwall with forward-facing or backward-facing step. Thermochromic liquid crystal (TLC technique with steady-state heat transfer experiments was used to obtain the whole-field film cooling effectiveness. Results show that, at low turbulence intensity, increasing Reynolds number decreases the effectiveness in most of the vane passage. There is no monotonic trend of influence by Reynolds number at high turbulence intensity. The effect of blowing ratio on the effectiveness has opposite trends at low and high turbulence levels. Increasing turbulent intensity decreases the effectiveness, especially near the inlet of the vane passage. With a stepped endwall, turbulence intensity has only mild effect on the film cooling effectiveness.

  1. Cooled perch effects on performance and well-being traits in caged White Leghorn hens.

    Science.gov (United States)

    Hu, J Y; Hester, P Y; Makagon, M M; Vezzoli, G; Gates, R S; Xiong, Y J; Cheng, H W

    2016-12-01

    We assessed the effects of chilled water cooling perches on hen performance and physiological and behavioral parameters under "natural" high temperatures during the 2013 summer with a 4-hour acute heating episode. White Leghorns at 16 wk of age (N = 162) were randomly assigned to 18 cages (n = 9) arranged into 3 units. Each unit was assigned to one of the 3 treatments through 32 wk of age: 1) cooled perches, 2) air perches, and 3) no perches. Chilled water (10°C) was circulated through the cooled perches when cage ambient temperature exceeded 25°C. At the age of 27.6 wk, hens were subjected to a 4-hour acute heating episode of 33.3°C and plasma corticosterone was determined within 2 hours. Egg production was recorded daily. Feed intake and egg and shell quality were measured at 5-week intervals. Feather condition, foot health, adrenal and liver weights, plasma corticosterone, and heat shock protein 70 mRNA were determined at the end of the study at 32 wk of age. The proportion of hens per cage perching, feeding, drinking, panting, and wing spreading was evaluated over one d every 5 wks and on the d of acute heat stress. There were no treatment effects on the measured physiological and production traits except for nail length. Nails were shorter for cooled perch hens than control (P = 0.002) but not air perch hens. Panting and wing spread were observed only on the day of acute heat stress. The onset of both behaviors was delayed for cooled perch hens, and they perched more than air perch hens following acute heat stress (P = 0.001) and at the age 21.4 wk (P = 0.023). Cooled perch hens drank less than control (P = 0.019) but not air perch hens at the age 21.4 wk. These results indicate that thermally cooled perches reduced thermoregulatory behaviors during acute heat stress, but did not affect their performance and physiological parameters under the ambient temperature imposed during this study. Published by Oxford University Press on behalf of

  2. Performance Analysis of an Updraft Tower System for Dry Cooling in Large-Scale Power Plants

    Directory of Open Access Journals (Sweden)

    Haotian Liu

    2017-11-01

    Full Text Available An updraft tower cooling system is assessed for elimination of water use associated with power plant heat rejection. Heat rejected from the power plant condenser is used to warm the air at the base of an updraft tower; buoyancy-driven air flows through a recuperative turbine inside the tower. The secondary loop, which couples the power plant condenser to a heat exchanger at the tower base, can be configured either as a constant-pressure pump cycle or a vapor compression cycle. The novel use of a compressor can elevate the air temperature in the tower base to increases the turbine power recovery and decrease the power plant condensing temperature. The system feasibility is evaluated by comparing the net power needed to operate the system versus alternative dry cooling schemes. A thermodynamic model coupling all system components is developed for parametric studies and system performance evaluation. The model predicts that constant-pressure pump cycle consumes less power than using a compressor; the extra compression power required for temperature lift is much larger than the gain in turbine power output. The updraft tower system with a pumped secondary loop can allow dry cooling with less power plant efficiency penalty compared to air-cooled condensers.

  3. Experimental investigation of the performance characteristics of a counterflow wet cooling tower

    International Nuclear Information System (INIS)

    Lemouari, M.; Boumaza, M.

    2010-01-01

    An experimental investigation of the performance characteristics of a counter flow wet cooling tower represented by the heat rejected by the tower and its thermal effectiveness is presented in this paper. The tower is filled with a 'VGA.' (Vertical Grid Apparatus) type packing which is 0.42 m high and contains four (04) galvanized sheets having a zigzag form, between which are disposed three (03) metallic vertical grids in parallel with a cross-sectional test area of 0.15 m - 0.148 m. The investigation is concerned mainly on the effect of the air, water flow rates and the inlet water temperatures on the thermal effectiveness of the cooling tower as well as the heat rejected by this tower from water to be cooled to the air stream discharged into the atmosphere. The two operating regimes which were observed during the air/water contact inside the tower, a Pellicular Regime (PR) and a Bubble and Dispersion Regime (BDR) appear to be important, as The BDR regime enables to cool larger amount of water flow rates, while the Pellicular regime results with higher thermal effectiveness. (authors)

  4. Performance Analysis of Photovoltaic Panels with Earth Water Heat Exchanger Cooling

    Directory of Open Access Journals (Sweden)

    Jakhar Sanjeev

    2016-01-01

    Full Text Available The operating temperature is an important factor affecting the performance and life span of the Photovoltaic (PV panels. The rising temperature can be maintained within certain limit using proper cooling techniques. In the present research a novel system for cooling of PV panels named as Earth Water Heat Exchanger (EWHE is proposed and modelled in transient analysis simulation tool (TRNSYS v17.0 for the conditions of Pilani, Rajasthan (India.The various parameters which include cell temperature, PV power output and cell efficiency are observed with respect to variation in mass flow rate of fluid. Simulation results of the system without cooling show that the maximum PV panel temperature reached up to 79.31 °C with electrical efficiency dropped to 9% during peak sunshine hour. On the other hand, when PV panels are coupled with EWHE system, the panel temperature drops to 46.29 °C with an efficiency improving to 11% for a mass flow rate of 0.022 kg/s. In the end the cooling potential of EWHE is found to be in direct correlation with mass flow rate. The proposed system is very useful for the arid regions of western India which are blessed with high solar insolation throughout the year.

  5. Effect of solar radiation on the performance of cross flow wet cooling tower in hot climate of Iran

    Science.gov (United States)

    Banooni, Salem; Chitsazan, Ali

    2016-11-01

    In some cities such as Ahvaz-Iran, the solar radiation is very high and the annual-mean-daily of the global solar radiation is about 17.33 MJ m2 d-1. Solar radiation as an external heat source seems to affect the thermal performance of the cooling towers. Usually, in modeling cooling tower, the effects of solar radiation are ignored. To investigate the effect of sunshade on the performance and modeling of the cooling tower, the experiments were conducted in two different states, cooling towers with and without sunshade. In this study, the Merkel's approach and finite difference technique are used to predict the thermal behavior of cross flow wet cooling tower without sunshade and the results are compared with the data obtained from the cooling towers with and without sunshade. Results showed that the sunshade is very efficient and it reduced the outlet water temperature, the approach and the water exergy of the cooling tower up to 1.2 °C, 15 and 1.1 %, respectively and increased the range and the efficiency of the cooling tower up to 29 and 37 %, respectively. Also, the sunshade decreased the error between the experimental data of the cooling tower with sunshade and the modeling results of the cooling tower without sunshade 1.85 % in average.

  6. Performance of materials in the component cooling water systems of pressurized water reactors

    International Nuclear Information System (INIS)

    Lee, B.S.

    1993-01-01

    The component cooling water (CCW) system provides cooling water to several important loads throughout the plant under all operating conditions. An aging assessment CCW systems in pressurized water reactors (PWRs) was conducted as part of Nuclear Plant Aging Research Program (NPAR) instituted by the US Nuclear Regulatory Commission. This paper presents some of the results on the performances of materials in respect of their application in CCW Systems. All the CCW system failures reported to the Nuclear Plant Reliability Data System (NPRDS) from January 1988 to June 1990 were reviewed; it is concluded that three of the main contributors to CCW system failures are valves, pumps, and heat exchangers. This study identified the modes and causes of failure for these components; most of the causes for the aging-related failures could be related to the performance of materials. Also, in this paper the materials used for these components are reviewed, and there aging mechanisms under CCW system conditions are discussed

  7. Comparative economic performance of selected passive solar heating and cooling technologies

    Science.gov (United States)

    Rutter, W.

    1981-05-01

    The economic performance of selected passive solar heating and cooling technologies which incorporate energy storage is assessed by using a set of uniform assumptions and methodologies. Where data are available, a given system is assessed at more than one geographical location. Results are obtained in the form of both payback period and net present value for residential applications, and in terms of net present value only for industrial/commercial uses. Results indicate that ventilated trombe walls, solar roof ponds, and certain night effect/floor storage strategies are cost effective, but night effect/rock bed cooling is not. Results also show that, although direct gain out-performs trombe walls in most parts of the country, both direct gain and trombe walls usually produce a net savings in the residential sector. Generally, however, tax regulations result in net economic loss for direct gain and trombe walls used to heat industrial and commercial buildings.

  8. Temperature Mapping of Air Film-Cooled Thermal Barrier Coated Surfaces Using Cr-Doped GdAlO3 Phosphor Thermography

    Science.gov (United States)

    Eldridge, Jeffrey I.; Shyam, Vikram; Wroblewski, Adam C.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.

    2016-01-01

    It has been recently shown that the high luminescence intensity from a Cr-doped GdAlO3 (Cr:GdAlO3) thermographic phosphor enables non-rastered full-field temperature mapping of thermal barrier coating (TBC) surfaces to temperatures above 1000C. In this presentation, temperature mapping by Cr:GdAlO3 based phosphor thermometry of air film-cooled TBC-coated surfaces is demonstrated for both scaled-up cooling hole geometries as well as for actual components in a burner rig test environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and advantages of this method over infrared thermography as well as the limitations of this method for studying air film cooling are discussed.

  9. On how high performers keep cool brains in situations of cognitive overload.

    Science.gov (United States)

    Jaeggi, Susanne M; Buschkuehl, Martin; Etienne, Alex; Ozdoba, Christoph; Perrig, Walter J; Nirkko, Arto C

    2007-06-01

    What happens in the brain when we reach or exceed our capacity limits? Are there individual differences for performance at capacity limits? We used functional magnetic resonance imaging (fMRI) to investigate the impact of increases in processing demand on selected cortical areas when participants performed a parametrically varied and challenging dual task. Low-performing participants respond with large and load-dependent activation increases in many cortical areas when exposed to excessive task requirements, accompanied by decreasing performance. It seems that these participants recruit additional attentional and strategy-related resources with increasing difficulty, which are either not relevant or even detrimental to performance. In contrast, the brains of the high-performing participants "keep cool" in terms of activation changes, despite continuous correct performance, reflecting different and more efficient processing. These findings shed light on the differential implications of performance on activation patterns and underline the importance of the interindividual-differences approach in neuroimaging research.

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

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1980-01-01

    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

  11. Optimization of advanced gas-cooled reactor fuel performance by a stochastic method

    International Nuclear Information System (INIS)

    Parks, G.T.

    1987-01-01

    A brief description is presented of a model representing the in-core behaviour of a single advanced gas-cooled reactor fuel channel, developed specifically for optimization studies. The performances of the only suitable Numerical Algorithms Group (NAG) library package and a Metropolis algorithm routine on this problem are discussed and contrasted. It is concluded that, for the problem in question, the stochastic Metropolis algorithm has distinct advantages over the deterministic NAG routine. (author)

  12. Isolated effects of peripheral arm and central body cooling on arm performance.

    Science.gov (United States)

    Giesbrecht, G G; Wu, M P; White, M D; Johnston, C E; Bristow, G K

    1995-10-01

    Whole body cooling impairs manual arm performance. The independent contributions of local (peripheral) and/or whole body (central) cooling are not known. Therefore, a protocol was developed in which the arm and the rest of the body could be independently cooled. Biceps temperature (Tmus), at a depth of 20 mm, and esophageal temperature (Tes) were measured. Six subjects were immersed to the clavicles in a tank (body tank) of water under 3 conditions: 1) cold body-cold arm (CB-CA); 2) warm body-cold arm (WB-CA); and 3) cold body-warm arm (CB-WA). In the latter two conditions, subjects placed their dominant arm in a separate (arm) tank. Water temperature (Tw) in each tank was independently controlled. In conditions requiring cold body and/or cold arm, Tw in the appropriate tanks was 8 degrees C. In conditions requiring warm body and/or warm arm, Tw in the appropriate tanks was adjusted between 29 and 38 degrees C to maintain body/arm temperature at baseline values. A battery of 6 tests, requiring fine or gross motor movements, were performed immediately before immersion and after 15, 45, and 70 minutes of immersion. In CB-CA, Tes decreased from an average of 37.2 to 35.6 degrees C and Tmus decreased from 34.6 to 22.0 degrees C. In WB-CA, Tmus decreased to 18.1 degrees C (Tes = 37.1 degrees C), and in CB-WA, Tes decreased to 35.8 degrees C (Tmus = 34.5 degrees C). By the end of immersion, there were significant decrements (43-85%) in the performance of all tests in CB-CA and WB-CA (p body and/or the arm elicits large decrements in finger, hand and arm performance. The decrements are due almost entirely to the local effects of arm tissue cooling.

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

    International Nuclear Information System (INIS)

    Pathania, R.S.; Tatone, O.S.

    1979-02-01

    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)

  14. Oxygen flooding and sample cooling during depth profiling of HfSiON thin films

    Energy Technology Data Exchange (ETDEWEB)

    Miwa, Shiro [Materials Analysis Center, Materials Laboratories, Sony Corporation, 4-16-1 Okata, Atsugi 243-0021 (Japan)], E-mail: Shiro.Miwa@jp.sony.com

    2008-12-15

    A combination of oxygen flooding and. Cs primary ion bombardment can suppress the enhancement of the secondary ion signal at the surface and at the interface of a thin HfSiON layer on a Si substrate. The surface concentration of both Cs and O during Cs primary ion bombardment with oxygen flooding was higher than that without oxygen flooding, as confirmed by X-ray photoelectron spectroscopy. When the sample was cooled to about -150 deg. C, the enhancement of the secondary ion signal could be suppressed at a lower oxygen pressure.

  15. High performance thin-film composite forward osmosis membrane.

    Science.gov (United States)

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A; Schiffman, Jessica D; Elimelech, Menachem

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 mum) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m(2-)h(-1), while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution.

  16. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 μm) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m2-h-1, while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution. © 2010 American Chemical Society.

  17. Performance comparison of liquid metal and gas cooled ATW system point designs

    International Nuclear Information System (INIS)

    Yang, W.S.; Taiwo, T.A.; Hill, R.N.; Khalil, H.S.; Wade, D.C.

    2001-01-01

    As part of the Advanced Accelerator Application (AAA) program in the U.S., preliminary design studies have been performed at Argonne National Laboratory (ANL) and Los Alamos National Laboratory (LANL) to define and compare candidate Accelerator Transmutation of Waste (ATW) systems. The studies at ANL have focused primarily on the transmutation blanket component of the overall system. Lead-bismuth eutectic (LBE), sodium, and gas cooled systems are among the blanket technology options currently under consideration. This paper summarizes the results from neutronics trade studies performed at ANL. Core designs have been developed for LBE and sodium cooled 840 MWt fast spectrum accelerator driven systems employing re-cycle. Additionally, neutronics analyses have been performed for a helium-cooled 600 MWt hybrid thermal and fast spectrum system proposed by General Atomics (GA), which is operated in the critical mode for three cycles and in a subcritical accelerator driven mode for a subsequent single cycle. For these three point designs, isotopic inventories, consumption rates, and annual burnup rates are compared. The mass flows and the ultimate loss of transuranic (TRU) isotopes to the waste stream per unit of heat generated during transmutation are also compared on a consistent basis. (author)

  18. Experimental study of cooling performance of pneumatic synthetic jet with singular slot rectangular orifice

    Science.gov (United States)

    Yu, Roger Ho Zhen; Ismail, Mohd Azmi bin; Ramdan, Muhammad Iftishah; Mustaffa, Nur Musfirah binti

    2017-03-01

    Synthetic Jet generates turbulence flow in cooling the microelectronic devices. In this paper, the experiment investigation of the cooling performance of pneumatic synthetic jet with single slot rectangular orifices at low frequency motion is presented. The velocity profile at the end of the orifice was measured and used as characteristic performance of synthetic jet in the present study. Frequencies of synthetic jet and the compressed air pressure supplied to the pneumatic cylinder (1bar to 5bar) were the parameters of the flow measurement. The air velocity of the synthetic jet was measured by using anemometer air flow meter. The maximum air velocity was 0.5 m/s and it occurred at frequency motion of 8 Hz. The optimum compressed air supplied pressure of the synthetic jet study was 4 bar. The cooling performance of synthetic jet at several driven frequencies from 0 Hz to 8 Hz and heat dissipation between 2.5W and 9W were also investigate in the present study. The results showed that the Nusselt number increased and thermal resistance decreased with both frequency and Reynolds number. The lowest thermal resistance was 5.25°C/W and the highest Nusselt number was 13.39 at heat dissipation of 9W and driven frequency of 8Hz.

  19. Part load performance of air-cooled centrifugal chillers with variable speed condenser fan control

    Energy Technology Data Exchange (ETDEWEB)

    Yu, F.W.; Chan, K.T. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2007-11-15

    Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71-0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile. (author)

  20. Effect of irreversible processes on the thermodynamic performance of open-cycle desiccant cooling cycles

    International Nuclear Information System (INIS)

    La, Dong; Li, Yong; Dai, Yanjun; Ge, Tianshu; Wang, Ruzhu

    2013-01-01

    Highlights: ► Effects of irreversible processes on the performance of desiccant cooling cycle are identified. ► The exergy destructions involved are classified by the properties of the individual processes. ► Appropriate indexes for thermodynamic evaluation are proposed based on thermodynamic analyses. - Abstract: Thermodynamic analyses of desiccant cooling cycle usually focus on the overall cycle performance in previous study. In this paper, the effects of the individual irreversible processes in each component on thermodynamic performance are analyzed in detail. The objective of this paper is to reveal the elemental features of the individual components, and to show their effects on the thermodynamic performance of the whole cycle in a fundamental way. Appropriate indexes for thermodynamic evaluation are derived based on the first and second law analyses. A generalized model independent of the connection of components is developed. The results indicate that as the effectiveness of the desiccant wheel increases, the cycle performance is increased principally due to the significant reduction in exergy carried out by exhaust air. The corresponding exergy destruction coefficient of the cycle with moderate performance desiccant wheel is decreased greatly to 3.9%, which is more than 50% lower than that of the cycle with low performance desiccant wheel. The effect of the heat source is similar. As the temperature of the heat source increases from 60 °C to 90 °C, the percentage of exergy destruction raised by exhaust air increases sharply from 5.3% to 21.8%. High heat exchanger effectiveness improves the cycle performance mainly by lowering the irreversibility of the heat exchanger, using less regeneration heat and pre-cooling the process air effectively

  1. Thermal performance of a multiple PCM thermal storage unit for free cooling

    International Nuclear Information System (INIS)

    Mosaffa, A.H.; Infante Ferreira, C.A.; Talati, F.; Rosen, M.A.

    2013-01-01

    Highlights: ► Numerical analysis on the performance of a thermal storages as free cooling system. ► Employing multiple PCMs to enhance heat transfer rate in thermal storages. ► Using an effective heat capacity method, the phase change parameters are determined. ► The effect of the slabs size and air channel thickness on COP is investigated. - Abstract: As demand for refrigeration and air conditioning increased during the last decade, the opportunities have expanded for using thermal energy storage (TES) systems in an economically advantageous manner in place of conventional cooling plants. Many cool storage systems use phase change materials (PCMs) and achieve peak load shifting in buildings. This work presents numerical investigations of the performance enhancement of a free cooling system using a TES unit employing multiple PCMs. The TES unit is composed of a number of rectangular channels for the flowing heat transfer fluid, separated by PCM slabs. Using the effective heat capacity method, the melting and solidification of the PCM is solved. The forced convective heat transfer inside the channels is analyzed by solving the energy equation, which is coupled with the heat conduction equation in the container wall. The effect of design parameters such as PCM slab length, thickness and fluid passage gap on the storage performance is also investigated using an energy based optimization. The results show that a system which can guarantee comfort conditions for the climate of Tabriz, Iran has an optimum COP of 7.0. This could be achieved by a combination of CaCl 2 ·6H 2 O with RT25 with the optimum air channel thickness of 3.2 mm, length of 1.3 m and PCM slab thickness of 10 mm

  2. Boost Converter Fed High Performance BLDC Drive for Solar PV Array Powered Air Cooling System

    Directory of Open Access Journals (Sweden)

    Shobha Rani Depuru

    2017-01-01

    Full Text Available This paper proposes the utilization of a DC-DC boost converter as a mediator between a Solar Photovoltaic (SPV array and the Voltage Source Inverters (VSI in an SPV array powered air cooling system to attain maximum efficiency. The boost converter, over the various common DC-DC converters, offers many advantages in SPV based applications. Further, two Brushless DC (BLDC motors are employed in the proposed air cooling system: one to run the centrifugal water pump and the other to run a fan-blower. Employing a BLDC motor is found to be the best option because of its top efficiency, supreme reliability and better performance over a wide range of speeds. The air cooling system is developed and simulated using the MATLAB/Simulink environment considering the steady state variation in the solar irradiance. Further, the efficiency of BLDC drive system is compared with a conventional Permanent Magnet DC (PMDC motor drive system and from the simulated results it is found that the proposed system performs better.

  3. Investigation of Stratified Thermal Storage Tank Performance for Heating and Cooling Applications

    Directory of Open Access Journals (Sweden)

    Azharul Karim

    2018-04-01

    Full Text Available A large amount of energy is consumed by heating and cooling systems to provide comfort conditions for commercial building occupants, which generally contribute to peak electricity demands. Thermal storage tanks in HVAC systems, which store heating/cooling energy in the off-peak period for use in the peak period, can be used to offset peak time energy demand. In this study, a theoretical investigation on stratified thermal storage systems is performed to determine the factors that significantly influence the thermal performance of these systems for both heating and cooling applications. Five fully-insulated storage tank geometries, using water as the storage medium, were simulated to determine the effects of water inlet velocity, tank aspect ratio and temperature difference between charging (inlet and the tank water on mixing and thermocline formation. Results indicate that thermal stratification enhances with increased temperature difference, lower inlet velocities and higher aspect ratios. It was also found that mixing increased by 303% when the temperature difference between the tank and inlet water was reduced from 80 °C to 10 °C, while decreasing the aspect ratio from 3.8 to 1.0 increased mixing by 143%. On the other hand, increasing the inlet water velocity significantly increased the storage mixing. A new theoretical relationship between the inlet water velocity and thermocline formation has been developed. It was also found that inlet flow rates can be increased, without increasing the mixing, after the formation of the thermocline.

  4. Thermal performance experiments on ultimate heat sinks, spray ponds, and cooling ponds

    International Nuclear Information System (INIS)

    Hadlock, R.K.

    1976-12-01

    A program of measurement on a Battelle-Northwest (BNW) spray pond has been completed to prove an integrated instrumentation system for application in future field experiments. The measurement programs in the field will produce data of relevance to the design and understanding of performance for ultimate heat sinks as components of emergency core cooling systems. In the absence of active emergency cooling systems, the data will be obtained on analog systems--prime candidates among these are the naturally-occurring hot ponds at Yellowstone National Park and man-made hot cooling ponds at Savannah River National Laboratory as well as spray ponds at various industrial facilities. The proof experiment has provided data that not only illustrate the effectiveness of the instrumentation system but also display interesting site-specific heat transfer processes. The data to be obtained in the field will also be site specific but must be of generic applicability in modeling for design and performance purposes. The integrated instrumentation system will evolve, through modest modifications and substantial supplementation, to provide the requisite data for the more demanding situation of work in and about hot water

  5. Measured performance of a 3 ton LiBr absorption water chiller and its effect on cooling system operation

    Science.gov (United States)

    Namkoong, D.

    1976-01-01

    A three ton lithium bromide absorption water chiller was tested for a number of conditions involving hot water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It was concluded that a three-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  6. Measured performance of a 3-ton LiBr absorption water chiller and its effect on cooling system operation

    Science.gov (United States)

    Namkoong, D.

    1976-01-01

    A 3-ton lithium bromide absorption water chiller was tested for a number of conditions involving hot-water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It is concluded that a 3-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  7. Vapor-cooled lead and stacks thermal performance and design analysis by finite difference techniques

    International Nuclear Information System (INIS)

    Peck, S.D.; Christensen, E.H.; O'Loughlin, J.M.

    1985-01-01

    Investigation of the combined thermal performance of the stacks and vapor cooled leads for the Mirror Fusion Test Facility-''B'' demonstrates considerable interdependency. For instance, the heat transfer to the vapor-cooled lead (VCL) from warm bus heaters, environmental enclosure, and stack is a significant additional heat load to the joule heating in the leads, proportionately higher for the lower current leads that have fewer current-carrying, counter flow coolant copper tubes. Consequently, the specific coolant flow (G/sec-kA-lead pair) increases as the lead current decreases. The definition of this interdependency and the definition of necessary thermal management has required an integrated thermal model for the entire stack/VCL assemblies

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

    International Nuclear Information System (INIS)

    Tatone, O.S.; Meindl, P.; Taylor, G.F.

    1986-06-01

    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

  9. Coupling model and solving approach for performance evaluation of natural draft counter-flow wet cooling towers

    Directory of Open Access Journals (Sweden)

    Wang Wei

    2016-01-01

    Full Text Available When searching for the optimum condenser cooling water flow in a thermal power plant with natural draft cooling towers, it is essential to evaluate the outlet water temperature of cooling towers when the cooling water flow and inlet water temperature change. However, the air outlet temperature and tower draft or inlet air velocity are strongly coupled for natural draft cooling towers. Traditional methods, such as trial and error method, graphic method and iterative methods are not simple and efficient enough to be used for plant practice. In this paper, we combine Merkel equation with draft equation, and develop the coupled description for performance evaluation of natural draft cooling towers. This model contains two inputs: the cooling water flow, the inlet cooling water temperature and two outputs: the outlet water temperature, the inlet air velocity, equivalent to tower draft. In this model, we furthermore put forward a soft-sensing algorithm to calculate the total drag coefficient instead of empirical correlations. Finally, we design an iterative approach to solve this coupling model, and illustrate three cases to prove that the coupling model and solving approach proposed in our paper are effective for cooling tower performance evaluation.

  10. An exergy analysis on the performance of a counterflow wet cooling tower

    International Nuclear Information System (INIS)

    Muangnoi, Thirapong; Asvapoositkul, Wanchai; Wongwises, Somchai

    2007-01-01

    Cooling towers are used to extract waste heat from water to atmospheric air. An energy analysis is usually used to investigate the performance characteristics of cooling tower. However, the energy concept alone is insufficient to describe some important viewpoints on energy utilization. In this study, an exergy analysis is used to indicate exergy and exergy destruction of water and air flowing through the cooling tower. Mathematical model based on heat and mass transfer principle is developed to find the properties of water and air, which will be further used in exergy analysis. The model is validated against experimental data. It is noted from the results that the amount of exergy supplied by water is larger than that absorbed by air, because the system produces entropy. To depict the utilizable exergy between water and air, exergy of each working fluid along the tower are presented. The results show that water exergy decreases continuously from top to bottom. On the other hand, air exergy is expressed in terms of convective and evaporative heat transfer. Exergy of air via convective heat transfer initially loses at inlet and slightly recovers along the flow before leaving the tower. However, exergy of air via evaporative heat transfer is generally high and able to consume exergy supplied by water. Exergy destruction is defined as the difference between water exergy change and air exergy change. It reveals that the cooling processes due to thermodynamics irreversibility perform poorly at bottom and gradually improve along the height of the tower. The results show that the lowest exergy destruction is located at the top of the tower

  11. Comparison of Core Performance with Various Oxide fuels on Sodium Cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin Ha; Kim, Myung Hyun [Kyung Hee University, Yongin (Korea, Republic of)

    2016-05-15

    The system is called Prototype GenIV Sodium-cooled Fast Reactor (PGSFR). Ultimate goal of PGSFR is test for capability of TRU transmutation. Purpose of this study is test for evaluation of in-core performance and TRU transmutation performance by applying various oxide fuel loaded TRU. Fuel type of reference core is changed to uranium-based oxide fuel. Oxide fuel has a lot of experience through fuel fabrication and reactor operation. This study performed by compared and analyzed a core performance of various oxide fuels. (U,Pu)O{sub 2} and (U,TRU)O{sub 2} which various oxide fuel types are selected as extreme case for comparison with core performance and transmutation capability of TRU isotopes. Thorium-based fuel is known that it has good performance for burner reactor due to low proliferation characteristic. To check the performance of TRU incineration for comparison with uranium-based fuel on prototype SFR, Thorium-based fuel, (Th,U)O{sub 2}, (Th,Pu)O{sub 2} and (Th,TRU)O{sub 2}, is selected. Calculations of core performance for various oxide fuel are performed using the fast calculation tool, TRANSX / DANTSTS / REBUS-3. In this study, comparison of core performance and transmutation performance is conducted with various fuel types in a sodium-cooled fast reactor. Mixed oxide fuel with TRU can produce the energy with small amount of fissile material. However, the TRU fuel is confirmed to bring a potential decline of the safety parameters. In case of (Th,U)O2 fuel, the flux level in thermal neutron region becomes lower because of higher capture cross-section of Th-232 than U-238. However, Th-232 has difficulty in converting to TRU isotopes. Therefore, the TRU consumption mass is relatively high in mixed oxide fuel with thorium and TRU.

  12. Comparison of Core Performance with Various Oxide fuels on Sodium Cooled Fast Reactor

    International Nuclear Information System (INIS)

    Choi, Jin Ha; Kim, Myung Hyun

    2016-01-01

    The system is called Prototype GenIV Sodium-cooled Fast Reactor (PGSFR). Ultimate goal of PGSFR is test for capability of TRU transmutation. Purpose of this study is test for evaluation of in-core performance and TRU transmutation performance by applying various oxide fuel loaded TRU. Fuel type of reference core is changed to uranium-based oxide fuel. Oxide fuel has a lot of experience through fuel fabrication and reactor operation. This study performed by compared and analyzed a core performance of various oxide fuels. (U,Pu)O_2 and (U,TRU)O_2 which various oxide fuel types are selected as extreme case for comparison with core performance and transmutation capability of TRU isotopes. Thorium-based fuel is known that it has good performance for burner reactor due to low proliferation characteristic. To check the performance of TRU incineration for comparison with uranium-based fuel on prototype SFR, Thorium-based fuel, (Th,U)O_2, (Th,Pu)O_2 and (Th,TRU)O_2, is selected. Calculations of core performance for various oxide fuel are performed using the fast calculation tool, TRANSX / DANTSTS / REBUS-3. In this study, comparison of core performance and transmutation performance is conducted with various fuel types in a sodium-cooled fast reactor. Mixed oxide fuel with TRU can produce the energy with small amount of fissile material. However, the TRU fuel is confirmed to bring a potential decline of the safety parameters. In case of (Th,U)O2 fuel, the flux level in thermal neutron region becomes lower because of higher capture cross-section of Th-232 than U-238. However, Th-232 has difficulty in converting to TRU isotopes. Therefore, the TRU consumption mass is relatively high in mixed oxide fuel with thorium and TRU.

  13. Performance of introducing outdoor cold air for cooling a plant production system with artificial light

    Directory of Open Access Journals (Sweden)

    Jun eWang

    2016-03-01

    Full Text Available The commercial use of a plant production system with artificial light (PPAL is limited by its high initial construction and operation costs. The electric-energy consumed by heat pumps, applied mainly for cooling, accounts for 15-35% of the total electric-energy used in a PPAL. To reduce the electric-energy consumption, an air exchanger with low capacity (180 W was used for cooling by introducing outdoor cold air. In this experiment, the indoor air temperature in two PPALs (floor area: 6.2 m2 each was maintained at 25ºC and 20ºC during light and dark periods, respectively, for lettuce production. In one PPAL (PPALe, an air exchanger (air flow rate: 250 m3 h-1 was used along with a heat pump (cooling capacity: 3.2 kW to maintain the indoor air temperature at the set-point. The other PPAL (PPALc with only a heat pump (cooling capacity: 3.2 kW was used for reference. Effects of introducing outdoor cold air on energy use efficiency, coefficient of performance (COP, electric-energy consumption for cooling and growth of lettuce were investigated. The results show that: when the air temperature difference between indoor and outdoor ranged from 20.2°C to 30.0°C: 1 the average energy use efficiency of the air exchanger was 2.8 and 3.4 times greater than the COP of the heat pumps in the PPALe and PPALc, respectively; 2 hourly electric-energy consumption in the PPALe reduced by 15.8-73.7% compared with that in the PPALc; 3 daily supply of CO2 in the PPALe reduced from 0.15 kg to 0.04 kg compared with that in the PPALc; 4 no significant difference in lettuce growth was observed in both PPALs. The results indicate that using air exchanger to introduce outdoor cold air should be considered as an effective way to reduce electric-energy consumption for cooling with little effects on plant growth in a PPAL.

  14. Cooling of a microchannel with thin evaporating liquid film sheared by dry gas flow

    Science.gov (United States)

    Kabova, Yu O.; Kuznetsov, V. V.

    2017-11-01

    A joint motion of thin liquid film and dry gas in a microchannel is investigated numerically at different values of initial concentration of the liquid vapor in the gas phase, taking into account the evaporation process. Major factors affecting the temperature distribution in the liquid and the gas phases are as follows: transfer of heat by liquid and gas flows, heat loses due to evaporation, diffusion heat exchange. Comparisons of the numerical results for the case of the dry gas and for the case of equilibrium concentration of vapor in the gas have been carried out. It is shown that use of dry gas enhances the heat dissipation from the heater. It is found out that not only intense evaporation occurs near the heating areas, but also in both cases vapor condensation takes place below the heater in streamwise direction.

  15. Upgrading the seismic performance of the interior water pipe supporting system of a cooling tower

    International Nuclear Information System (INIS)

    Manos, G.C.; Soulis, V.J.

    2005-01-01

    This paper presents results from a numerical study that was performed in order to simulate the seismic behavior of the interior support system of the piping and cooling features of a cooling tower in one of the old power stations located in an area at the North-Western part of Greece. This cooling tower has a diameter of 60 m and a height of 100 m. The interior piping support system consists mainly of a series of nine-meter high pre-cast vertical columns made by pre-stressed concrete; these columns, together with reinforced concrete pre-cast horizontal beams that are joined monolithically with the columns at their top, form the old interior supporting system. This system represented a very flexible structure, a fact that was verified from a preliminary numerical analysis of its seismic behavior. The maximum response to the design earthquake levels resulted in large horizontal displacements at the top of the columns as well as overstress to some of the columns. The most important part of the current numerical investigation was to examine various strengthening schemes of the old interior support system and to select one that will demonstrate acceptable seismic behavior. (authors)

  16. Numerical and Experimental Investigation on the Performance of a Thermoelectric Cooling Automotive Seat

    Science.gov (United States)

    Su, Chuqi; Dong, Wenbin; Deng, Yadong; Wang, Yiping; Liu, Xun

    2018-06-01

    Heating, ventilating and air conditioning (HVAC) is the most significant auxiliary load in vehicles and largely increases extra emissions. Therefore, thermoelectric cooling automotive seat, a relatively new technology, is used in an attempt to reduce HVAC consumption and improve thermal comfort. In this study, three design schemes of the thermoelectric cooler (TEC) are proposed. Then the numerical simulation is used to analyze their heat transfer performance, and evaluate the improvement of the seat cooling in terms of the occupant back thermal comfort. Moreover, an experiment is conducted to validate the accuracy of the simulation results. The experimental results show that: (1) an average reduction in air temperature of 4°C in 60 s is obtained; (2) the temperature of the occupant's back drops from 33.5°C to 25.7°C in cooperation with the HVAC system; (3) back thermal comfort is greatly improved. As expected, the thermoelectric cooling automotive seat is able to provide an improvement in the occupant's thermal comfort at a reduced energy consumption rate, which makes it promising for vehicular application.

  17. Cooling performance and evaluation of automotive refrigeration system for a passenger car

    Science.gov (United States)

    Prajitno, Deendarlianto, Majid, Akmal Irfan; Mardani, Mahardeka Dhias; Wicaksono, Wendi; Kamal, Samsul; Purwanto, Teguh Pudji; Fauzun

    2016-06-01

    A new design of automotive refrigeration system for a passenger car was proposed. To ensure less energy consumption and optimal thermal comfort, the performance of the system were evaluated. This current research was aimed to evaluate the refrigeration characteristics of the system for several types of cooling load. In this present study, a four-passenger wagon car with 1500 cc gasoline engine that equipped by a belt driven compressor (BDC) was used as the tested vehicle. To represent the tropical condition, a set of lamps and wind sources are installed around the vehicle. The blower capacity inside a car is varied from 0.015 m/s to 0.027 m/s and the compressor speed is varied at variable 820, 1400, and 2100 rpm at a set temperature of 22°C. A set of thermocouples that combined by data logger were used to measure the temperature distribution. The system uses R-134a as the refrigerant. In order to determine the cooling capacity of the vehicle, two conditions were presented: without passengers and full load conditions. As the results, cooling capacity from any possible heating sources and transient characteristics of temperature in both systems for the cabin, engine, compressor, and condenser are presented in this work. As the load increases, the outlet temperature of evaporator also increases due to the increase of condensed air. This phenomenon also causes the increase of compressor work and compression ratio which associated to the addition of specific volume in compressor inlet.

  18. Nucleation behavior of melted Bi films at cooling rates from 101 to 104 K/s studied by combining scanning AC and DC nano-calorimetry techniques

    International Nuclear Information System (INIS)

    Xiao, Kechao; Vlassak, Joost J.

    2015-01-01

    Highlights: • We proposed a general data reduction scheme that combines scanning AC and DC calorimetry results for the study of reaction kinetics. • Calorimetry measurements at cooling rates ranging from 30 K/s to 20,000 K/s were achieved. • Upon initial melting, the Bi thin-film sample breaks up into thousands of isolated islands, and highly repeatable nucleation behavior is observed. • The nucleation rate of melted Bi is calculated, which can be well described by classical nucleation theory over a wide range of cooling rates. - Abstract: We study the nucleation behavior of undercooled liquid Bi at cooling rates ranging from 10 1 to 10 4 K/s using a combination of scanning DC and AC nano-calorimetry techniques. Upon initial melting, the Bi thin-film sample breaks up into silicon nitride-coated isolated islands. The number of islands in a typical sample is sufficiently large that highly repeatable nucleation behavior is observed, despite the stochastic nature of the nucleation process. We establish a data reduction technique to evaluate the nucleation rate from DC and AC calorimetry results. The results show that the driving force for the nucleation of melted Bi is well described by classical nucleation theory over a wide range of cooling rates. The proposed technique provides a unique and efficient way to examine nucleation kinetics with cooling rates over several orders of magnitude. The technique is quite general and can be used to evaluate reaction kinetics in other materials

  19. Evaluation of the performance of combined cooling, heating, and power systems with dual power generation units

    International Nuclear Information System (INIS)

    Knizley, Alta A.; Mago, Pedro J.; Smith, Amanda D.

    2014-01-01

    The benefits of using a combined cooling, heating, and power system with dual power generation units (D-CCHP) is examined in nine different U.S. locations. One power generation unit (PGU) is operated at base load while the other is operated following the electric load. The waste heat from both PGUs is used for heating and for cooling via an absorption chiller. The D-CCHP configuration is studied for a restaurant benchmark building, and its performance is quantified in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE). Cost spark spread, PEC spark spread, and CDE spark spread are examined as performance indicators for the D-CCHP system. D-CCHP system performance correlates well with spark spreads, with higher spark spreads signifying greater savings through implementation of a D-CCHP system. A new parameter, thermal difference, is introduced to investigate the relative performance of a D-CCHP system compared to a dual PGU combined heat and power system (D-CHP). Thermal difference, together with spark spread, can explain the variation in savings of a D-CCHP system over a D-CHP system for each location. The effect of carbon credits on operational cost savings with respect to the reference case is shown for selected locations. - Highlights: • We investigate benefits from using combined cooling, heating, and power systems. • A dual power generation unit configuration is considered for CCHP and CHP. • Spark spreads for cost, energy, and emissions correlate with potential savings. • Thermal difference parameter helps to explain variations in potential savings. • Carbon credits may increase cost savings where emissions savings are possible

  20. CARMENES-NIR channel spectrograph cooling system AIV: thermo-mechanical performance of the instrument

    Science.gov (United States)

    Becerril, S.; Mirabet, E.; Lizon, J. L.; Abril, M.; Cárdenas, C.; Ferro, I.; Morales, R.; Pérez, D.; Ramón, A.; Sánchez-Carrasco, M. A.; Quirrenbach, A.; Amado, P.; Ribas, I.; Reiners, A.; Caballero, J. A.; Seifert, W.; Herranz, J.

    2016-07-01

    CARMENES is the new high-resolution high-stability spectrograph built for the 3.5m telescope at the Calar Alto Observatory (CAHA, Almería, Spain) by a consortium formed by German and Spanish institutions. This instrument is composed by two separated spectrographs: VIS channel (550-1050 nm) and NIR channel (950- 1700 nm). The NIR-channel spectrograph's responsible is the Instituto de Astrofísica de Andalucía (IAACSIC). It has been manufactured, assembled, integrated and verified in the last two years, delivered in fall 2015 and commissioned in December 2015. One of the most challenging systems in this cryogenic channel involves the Cooling System. Due to the highly demanding requirements applicable in terms of stability, this system arises as one of the core systems to provide outstanding stability to the channel. Really at the edge of the state-of-the-art, the Cooling System is able to provide to the cold mass ( 1 Ton) better thermal stability than few hundredths of degree within 24 hours (goal: 0.01K/day). The present paper describes the Assembly, Integration and Verification phase (AIV) of the CARMENES-NIR channel Cooling System implemented at IAA-CSIC and later installation at CAHA 3.5m Telescope, thus the most relevant highlights being shown in terms of thermal performance. The CARMENES NIR-channel Cooling System has been implemented by the IAA-CSIC through very fruitful collaboration and involvement of the ESO (European Southern Observatory) cryo-vacuum department with Jean-Louis Lizon as its head and main collaborator. The present work sets an important trend in terms of cryogenic systems for future E-ELT (European Extremely Large Telescope) large-dimensioned instrumentation in astrophysics.

  1. Comparative study on thermal performance of natural draft cooling towers with finned shells

    Energy Technology Data Exchange (ETDEWEB)

    Goodarzi, Mohsen [Bu-Ali Sina Univ., Hamedan (Iran, Islamic Republic of). Dept. of Mechanical Engineering

    2016-10-15

    The cooling efficiency of natural draft cooling towers under crosswind condition should be improved. In the present research work three different externally finned shells were considered for a typical natural draft cooling tower to investigate the cooling improvement. They were numerically simulated under normal and crosswind conditions. Numerical results show that twisting four fin plates over the tower shell along the 45 peripheral angle, could improve the cooling efficiency up to 6.5 %. Because of the periodic shape of the fin plates, the cooling efficiency of the cooling tower with finned shell is less sensitive to the change of wind.

  2. Comparative study on thermal performance of natural draft cooling towers with finned shells

    International Nuclear Information System (INIS)

    Goodarzi, Mohsen

    2016-01-01

    The cooling efficiency of natural draft cooling towers under crosswind condition should be improved. In the present research work three different externally finned shells were considered for a typical natural draft cooling tower to investigate the cooling improvement. They were numerically simulated under normal and crosswind conditions. Numerical results show that twisting four fin plates over the tower shell along the 45 peripheral angle, could improve the cooling efficiency up to 6.5 %. Because of the periodic shape of the fin plates, the cooling efficiency of the cooling tower with finned shell is less sensitive to the change of wind.

  3. Construction and performance tests of a secondary hydrogen gas cooling system

    International Nuclear Information System (INIS)

    Sanokawa, K.; Hishida, M.

    1980-01-01

    With the aim of a multi-purpose use of nuclear energy, such as direct steel-making, an experimental multi-purpose high-temperature gas-cooled reactor (VHTR) is now being developed by the Japan Atomic Energy Research Institute (JAERI). In order to simulate a heat exchanging system between the primary helium gas loop and the secondary reducing gas system of the VHTR, a hydrogen gas loop as a secondary cooling system of the existing helium gas loop was completed in 1977, and was successfully operated for over 2000 hours. The objectives of constructing the H 2 secondary loop were: (1) To get basic knowledge for designing, constructing and operating a high-temperature and high-pressure gas facility; (2) To perform the following tests: (a) hydrogen permeation at the He/H 2 heat exchanger (the surfaces of the heat exchanger tubes are coated by calorizing to reduce hydrogen permeation), (b) thermal performance tests of the He/H 2 heat exchanger and the H 2 /H 2 regenerative heat exchanger, (c) performance test of internal insulation, and (d) performance tests of the components such as a H 2 gas heater and gas purifiers. These tests were carried out at He gas temperature of approximately 1000 0 C, H 2 gas temperature of approximately 900 0 C and gas pressures of approximately 40 kg/cm 2 G, which are almost the same as the operating conditions of the VHTR

  4. Performance of the diffusion barrier in the metallic fuel in sodium-cooled fast reactor

    International Nuclear Information System (INIS)

    Kim, Jun Hwan; Ryu, Ho Jin; Yang, Seong Woo; Lee, Byoung Oon; Oh, Seok Jin; Lee, Chan Bock; Hahn, Dohee

    2009-01-01

    The objectives in this study are to propose several kinds of barrier materials and to evaluate their performance to prevent a fuel-clad interaction situation between the metallic fuel and the clad material in the Sodium-cooled Fast Reactor (SFR). Metallic foil made from refractory element, electrodeposition of the Cr on the clad surface, and the vapor deposition of the Zr were used as the barrier layers. The diffusion couple test was performed at the temperature of 800degC for 25 hour. The results showed that considerable amount of reaction occurred at the specimen without barrier, whereas excellent performance was observed in that neither reaction nor inter-diffusion occurred in the case of metallic foil made of Cr or V. Electrodeposition was revealed to be excellent provided that optimum deposition condition can be found. Similar to the electro-deposition result, excellent performance observed in the case of vapor deposition condition. (author)

  5. Thermal Performance of a Dual-Channel, Helium-Cooled, Tungsten Heat Exchanger

    International Nuclear Information System (INIS)

    Youchison, Dennis L.; North, Mart T.

    2000-01-01

    Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion. Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m 2 and reached a maximum surface temperature of 593 C for uniform power loading of 3 kW absorbed on a 2-cm 2 area. An impressive 10 kW of power was absorbed on an area of 24 cm 2 . Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum RTDs for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels. The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m 2 using 50 C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented

  6. Performance evaluation of a stack cooling system using CO{sub 2} air conditioner in fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Chul; Won, Jong Phil [Thermal Management Research Center, Korea Automotive Technology Institute, Chungnam 330-912 (Korea); Park, Yong Sun; Lim, Tae Won [Corporate Research and Development Division, Hyundai-Kia Motors, Gyeonggi 449-912 (Korea); Kim, Min Soo [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea)

    2009-01-15

    A relation between the heat release from a fuel cell stack and an air conditioning system's performance was investigated. The air conditioning system installed in a fuel cell vehicle can be used for stack cooling when additional stack heat release is required over a fixed radiator capacity during high vehicle power generation. This study investigated the performance of a stack cooling system using CO{sub 2} air conditioner at various operating conditions. Also, the heat releasing effectiveness and mutual interference were analyzed and compared with those for the conventional radiator cooling system with/without cabin cooling. When the radiator coolant inlet temperature and flow rate were 65 C and 80 L/min, respectively, for the outdoor air inlet speed of 5 m/s, the heat release of the stack cooling system with the aid of CO{sub 2} air conditioner increased up to 36% more than that of the conventional radiator cooling system with cabin cooling. Furthermore, this increased by 7% versus the case without cabin cooling. (author)

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

    International Nuclear Information System (INIS)

    Tatone, O.S.; Tapping, R.L.

    1988-12-01

    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

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

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1980-02-01

    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)

  9. A cooling concept for improved field winding performance in large superconducting ac generators

    International Nuclear Information System (INIS)

    Laskaris, T.E.

    1977-01-01

    An analytical study of a flow circuit for large superconducting generator rotors is presented. The flow circuit provides regulation of the level of liquid in the rotor externally by adjusting the helium supply pressure. It also protects the vapour cooled structural members of the rotor from overcooling during transient periods of operation. Furthermore, it is capable of reducing the winding temperature below 4.2 K thereby enhancing the superconductor's performance. For example, a large generator rotor with NbTi superconducting field winding experiences approximately a 50% increase in its critical current density compared to that at 4.2 K. (author)

  10. Thermal-Hydraulic Performance of a Corrugated Cooling Fin with Louvered Surfaces

    DEFF Research Database (Denmark)

    Sønderby, Simon Kaltoft; Hosseini, Seyed Mojtaba Mir; Rezaniakolaei, Alireza

    2017-01-01

    The main objective of the article is to investigate thermal-hydraulic performance of a corrugated cooling fin with louvered surfaces. The investigation is carried out using the fin geometry of one most commonly used liquid-to-air heat exchangers. The investigation was carried out by numerically...... simulating the airflow with louvered fin geometry. The simulation model was verified by comparing simulated j- and f-factors with the corresponding values of several experimental correlations. The j-factors deviated less than 10.7 % from two of the experimental correlations, whereas deviations ranging...

  11. Comparative Effectiveness of Different Phase Change Materials to Improve Cooling Performance of Heat Sinks for Electronic Devices

    Directory of Open Access Journals (Sweden)

    Ahmad Hasan

    2016-08-01

    Full Text Available This paper thermo-physically characterizes salt hydrate, paraffin wax and milk fat as phase change materials (PCMs. The three PCMs are compared in terms of improving heat sink (HS performance for cooling electronic packaging. An experimental study is carried out on commercially available finned HS with and without PCM under natural ventilation (NV and forced ventilation (FV at different heat loads (4 W to 10 W. The results indicate that integration of all of the PCMs into the HS improves its cooling performance; however, milk fat lags behind the other two PCMs in terms of cooling produced. A three-dimensional pressure-based conjugate heat transfer model has been developed and validated with experimental results. The model predicts the parametric influence of PCM melting range, thermal conductivity and density on HS thermal management performance. The HS cooling performance improves with increased density and conductivity while it deteriorates with the wider melting range of the PCMs.

  12. Experimental and Numerical Study of the Effects of Acoustic Sound Absorbers on the Cooling Performance of Thermally Active Building Systems

    DEFF Research Database (Denmark)

    Domínguez, L. Marcos; Kazanci, Ongun Berk; Rage, Nils

    2017-01-01

    Free-hanging horizontal and vertical sound absorbers are commonly used in buildings for room acoustic control; however, when these sound absorbers are used in combination with Thermally Active Building Systems, they will decrease the cooling performance of Thermally Active Building Systems...... and this will affect the thermal indoor environment in that space. Therefore, it is crucial to be able to quantify and model these effects in the design phase. This study quantifies experimentally the effects of horizontal and vertical free-hanging sound absorbers on the cooling performance of Thermally Active......%, respectively. With vertical sound absorbers, the decrease in cooling performance was 8%, 12%, and 14% for the corresponding cases, respectively. The numerical model predicted closely the cooling performance reduction, air temperatures and ceiling surface temperatures in most cases, while there were differences...

  13. Construction and performance testing of a secondary cooling system with hydrogen gas (I)

    International Nuclear Information System (INIS)

    Hishida, M.; Nekoya, S.; Takizuka, T.; Emori, K.; Ogawa, M.; Ouchi, M.; Okamoto, Y.; Sanokawa, K.; Nakano, T.; Hagiwara, T.

    1979-08-01

    An experimental multi-purpose High-Temperature Gas Cooled Reactor (VHTR) which is supposed to be used for a direct steel-making is now being developed in JAeRI. In order to simulate the heat exchanging system between the primary helium gas and the secondary reducing gas system of VHTR, a hydrogen gas loop was constructed as a secondary cooling system of the helium gas loop. The maximum temperature and the maximum pressure of the hydrogen gas are 900 degrees C and 42 kg/cm 2 x G respectively. The construction of the hydrogen gas loop was completed in January, 1977, and was successfully operated for 1.000 h. Various performance tests, such as the hydrogen permeation test of a He/H2 heat exchanger and the thermal performance test of heat exchangers, were made. Especially, it was proved that hydrogen permeation rate through the heat exchanger was reduced to 1/30 to approximately 1/50 by a method of calorized coating, and the coating was stable during 1.000 h's operation. It was also stable against the temperature changes. This report describes the outline of the facility and performance of the components. (orig.) [de

  14. Performance evaluation of combined ejector LiBr/H2O absorption cooling cycle

    Directory of Open Access Journals (Sweden)

    Hasan Sh. Majdi

    2016-03-01

    Full Text Available The objective of this work is to develop a computer simulation program to evaluate the performance of solar-assited combined ejector absorption (single-effect cooling system using LiBr/H2O as a working fluid and operating under steady-state conditions. The ejector possess no moving parts and is simple and reliable, which makes it attractive for combination with single-stage absorption cycle for further improvement to the system's performance. In this research, improvement to the system is achieved by utilizing the potential kinetic energy of the ejector to enhance refrigeration efficiency. The effects of the entrainment ratio of the ejector, operating temperature, on the thermal loads, and system performance have been investigated. The results showed that the evaporator and condenser loads, post-addition of the ejector, is found to be permanently higher than that in the basic cycle, which indicates a significant enhancement of the proposed cycle and the cooling capacity of the system increasing with the increase in evaporator temperature and entrainment ratio. The COP of the modified cycle is improved by up to 60 % compared with that of the basic cycle at the given condition. This process stabilizes the refrigeration system, enhanced its function, and enabled the system to work under higher condenser temperatures.

  15. Thermodynamic performance analysis and optimization of a solar-assisted combined cooling, heating and power system

    International Nuclear Information System (INIS)

    Wang, Jiangjiang; Lu, Yanchao; Yang, Ying; Mao, Tianzhi

    2016-01-01

    This study aims to present a thermodynamic performance analysis and to optimize the configurations of a hybrid combined cooling, heating and power (CCHP) system incorporating solar energy and natural gas. A basic natural gas CCHP system containing a power generation unit, a heat recovery system, an absorption cooling system and a storage tank is integrated with solar photovoltaic (PV) panels and/or a heat collector. Based on thermodynamic modeling, the thermodynamic performance, including energy and exergy efficiencies, under variable work conditions, such as electric load factor, solar irradiance and installation ratio, of the solar PV panels and heat collector is investigated and analyzed. The results of the energy supply side analysis indicate that the integration of solar PV into the CCHP system more efficiently improves the exergy efficiency, whereas the integration of a solar heat collector improves the energy efficiency. To match the building loads, the optimization method combined with the operation strategy is employed to optimize the system configurations to maximize the integrated benefits of energy and economic costs. The optimization results of demand–supply matching demonstrate that the integration of a solar heat collector achieves a better integrated performance than the solar PV integration in the specific case study. - Highlights: • Design a CCHP system integrated with solar PV and heat collector. • Present the energy and exergy analyses under variable work conditions. • Propose an optimization method of CCHP system for demand-supply matching.

  16. Performance optimization of solar driven small-cooled absorption–diffusion chiller working with light hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Sayadi, Zouhour [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia); Ben Thameur, Nizar, E-mail: nizarbenthameur@yahoo.fr [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia); Bourouis, Mahmoud [Mechanical Engineering Department, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Bellagi, Ahmed [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia)

    2013-10-15

    Highlights: • 1 kW{sub cooling} diffusion/absorption machine with light hydrocarbons as working fluids. • Hysys optimization to choose the optimal mixture for a better machine performance. • Cooling loads for a small bed-room (16 m{sup 2}) have been estimated into TRNSYS. • Economic assessment to choose the best combination of solar equipments. • Energy savings, CO{sub 2} avoided and equivalent gasoil and Diesel saved energy. - Abstract: We present in this paper a HYSYS (Aspen One) model and simulation results for 1 kW capacity water-cooled absorption/diffusion machine using different binary mixtures of light hydrocarbons as working fluids (C{sub 3}/n-C{sub 6}, C{sub 3}/c-C{sub 6}, C{sub 3}/c-C{sub 5}, propylene/c-C{sub 5}, propylene/i-C{sub 4}, propylene/i-C{sub 5}) in combination with helium as inert gas. The driving heat is supposed to be provided by an evacuated solar collector field. TRNSYS is used to address the solar aspects of the simulations. For the optimal chiller the driving heat temperature was found to be 121 °C for an evaporator exit temperature of 0 °C. The cooling water flow rate circulating between chiller and cooling tower is 140 l/h. Bubble pump and generator are heated by pressurized water from an insulated tank (70 l/m{sup 2}) maintained at a maximum temperature of 126 °C – with make-up heat when needed – and storing solar heat at an estimated 4.2 kW power. The solar energy cover only 40% for the energy supplied to drive the chiller. It’s found that the necessary collector surface area is about 6 m{sup 2} with annually total costs of 1.60 €/kW h with 20 years lifetime period for the installation. The avoided CO{sub 2} emissions are estimated at 1396 kg. The equivalent saved energy is 521 l of diesel or 604 l of gasoline.

  17. Performance optimization of solar driven small-cooled absorption–diffusion chiller working with light hydrocarbons

    International Nuclear Information System (INIS)

    Sayadi, Zouhour; Ben Thameur, Nizar; Bourouis, Mahmoud; Bellagi, Ahmed

    2013-01-01

    Highlights: • 1 kW cooling diffusion/absorption machine with light hydrocarbons as working fluids. • Hysys optimization to choose the optimal mixture for a better machine performance. • Cooling loads for a small bed-room (16 m 2 ) have been estimated into TRNSYS. • Economic assessment to choose the best combination of solar equipments. • Energy savings, CO 2 avoided and equivalent gasoil and Diesel saved energy. - Abstract: We present in this paper a HYSYS (Aspen One) model and simulation results for 1 kW capacity water-cooled absorption/diffusion machine using different binary mixtures of light hydrocarbons as working fluids (C 3 /n-C 6 , C 3 /c-C 6 , C 3 /c-C 5 , propylene/c-C 5 , propylene/i-C 4 , propylene/i-C 5 ) in combination with helium as inert gas. The driving heat is supposed to be provided by an evacuated solar collector field. TRNSYS is used to address the solar aspects of the simulations. For the optimal chiller the driving heat temperature was found to be 121 °C for an evaporator exit temperature of 0 °C. The cooling water flow rate circulating between chiller and cooling tower is 140 l/h. Bubble pump and generator are heated by pressurized water from an insulated tank (70 l/m 2 ) maintained at a maximum temperature of 126 °C – with make-up heat when needed – and storing solar heat at an estimated 4.2 kW power. The solar energy cover only 40% for the energy supplied to drive the chiller. It’s found that the necessary collector surface area is about 6 m 2 with annually total costs of 1.60 €/kW h with 20 years lifetime period for the installation. The avoided CO 2 emissions are estimated at 1396 kg. The equivalent saved energy is 521 l of diesel or 604 l of gasoline

  18. Urban temperature analysis and impact on the building cooling energy performances: an Italian case study

    Directory of Open Access Journals (Sweden)

    Michele Zinzi

    2016-06-01

    Full Text Available Climate changes and urban sprawl are dramatically increasing the heat island effect in urban environments, whatever the size and the latitude are, affecting these latter parameters the effect intensity. The urban heats island is a phenomenon observed since the last decades of the XIX century but demonstrated at large scale only one century later, characterised by the increase of air temperature in densely built urban environments respect to the countryside surround cities. Many studies are available, showing urban heat island intensities up to 12°C. This thermal stress causes social, health and environmental hazards, with major consequences on weaker social classes, as elderly and low income people, it is not by chance that survey demonstrated the increase of deaths in such categories during intense and extended heat waves. This study presents the firs results on the observation of air temperature measures in different spots of Rome, city characterised by a typical Mediterranean climate and by a complex urban texture, in which densely built areas are kept separated by relatively green or not-built zones. Six spots are monitored since June 2014 and include: historical city centre, semi-central zones with different construction typologies, surrounding areas again with various urban and building designs. The paper is focused on the analysis of summer temperature profiles, increase respect to the temperature outside the cities and the impact on the cooling performance of buildings. Temperature datasets and a reference building model were inputted into the well-known and calibrated dynamic tool TRNSYS. Cooling net energy demand of the reference building was calculated, as well as the operative temperature evolution in the not cooled building configuration. The results of calculation allow to compare the energy and thermal performances in the urban environment respect to the reference conditions, usually adopted by building codes. Advice and

  19. Cooling load and coefficient of performance optimizations for real air-refrigerators

    International Nuclear Information System (INIS)

    Tu Youming; Chen Lingen; Sun Fengrui; Wu Chih

    2006-01-01

    Based on a simple irreversible variable-temperature heat reservoir air (Brayton) refrigeration cycle model, a performance analysis and optimization of a real air refrigerator is carried out using finite-time thermodynamics. To maximize the cooling load and the coefficient of performance (COP) of the cycle, the allocation of a fixed total heat-exchanger inventory and thermal-capacity rate matching between the working fluid and heat reservoirs are optimized, respectively. The influences of pressure ratio, the total heat-exchanger inventory, the efficiencies of the compressor and expander, the thermal capacity rate of the working fluid and the ratio of the thermal-capacity rates of the heat reservoirs on the performance of the cycle are shown by numerical examples. The results obtained provide guidances for the design of practical air-refrigeration plants

  20. Solar heating and cooling system with absorption chiller and low temperature latent heat storage: Energetic performance and operational experience

    Energy Technology Data Exchange (ETDEWEB)

    Helm, M.; Keil, C.; Hiebler, S.; Mehling, H.; Schweigler, C. [Bavarian Center for Applied Energy Research (ZAE Bayern) (Germany)

    2009-06-15

    Absorption cooling systems based on water/lithium bromide (LiBr) solution typically require an open wet cooling tower to transfer the reject heat to the ambient. Yet, water consumption, the need for water make-up and cleaning, formation of fog, and the risk of Legionella bacteria growth are hindering factors for the implementation of small solar cooling systems. The application of a latent heat storage supporting the heat rejection of the absorption chiller in conjunction with a dry cooling system allows eliminating the wet cooling tower. By that means heat rejection of the chiller is shifted to periods with lower ambient temperatures, i.e. night time or off-peak hours. The system concept and the hydraulic scheme together with an analysis of the energetic performance of the system are presented, followed by a report on the operation of a first pilot installation. (author)

  1. Performance Evaluation of an In-Wheel Motor Cooling System in an Electric Vehicle/Hybrid Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Dong Hyun Lim

    2014-02-01

    Full Text Available High power and miniaturization of motors in an in-wheel drive system, which is installed inside the wheels of a vehicle, are required for directly driving the wheels. In addition, an efficient cooling system is required to ensure high driving performance and durability. This study experimentally evaluated the heat dissipation performance of a 35-kW-class large-capacity in-wheel motor equipped with an internal-circulation-type oil-cooling system that exhibits high cooling performance and can be easily miniaturized to this motor. Temperatures of the coil and stator core of cooling systems with and without a radiator were measured in real time under in-wheel motor driving conditions. It was found that operating the cooling system at a continuous-rating maximum speed without the radiator was difficult. We confirmed that under continuous-rating base speed and continuous-rating maximum speed driving conditions, the cooling system with the radiator showed thermally stable operation. Furthermore, under maximum-rating base speed and maximum-rating maximum speed driving conditions, the cooling system with the radiator provided additional driving times of approximately 22 s and 2 s, respectively.

  2. Performance optimization of evacuated tube collector for solar cooling of a house in hot climate

    Science.gov (United States)

    Ghoneim, Adel A.

    2018-02-01

    Evacuating the space connecting cover and absorber significantly improves evacuated tube collector (ETC) performance. So, ETCs are progressively utilised all over the world. The main goal of current study is to explore ETC thermal efficiency in hot and severe climate like Kuwait weather conditions. A collector test facility was installed to record ETC thermal performance for one-year period. An extensively developed model for ETCs is presented, employing complete optical and thermal assessment. This study analyses separately optics and heat transfer in the evacuated tubes, allowing the analysis to be extended to different configurations. The predictions obtained are in agreement with experimental. The optimum collector parameters (collector tube length and diameter, mass flow rate and collector tilt angle) are determined. The present results indicate that the optimum tube length is 1.5 m, as at this length a significant improvement is achieved in efficiency for different tube diameters studied. Finally, the heat generated from ETCs is used for solar cooling of a house. Results of the simulation of cooling system indicate that an ETC of area 54 m2, tilt angle of 25° and storage tank volume of 2.1 m3 provides 80% of air-conditioning demand in a house located in Kuwait.

  3. Performance Estimation of Supercritical Co2 Micro Modular Reactor (MMR) for Varying Cooling Air Temperature

    International Nuclear Information System (INIS)

    Ahn, Yoonhan; Kim, Seong Gu; Cho, Seong Kuk; Lee, Jeong Ik

    2015-01-01

    A Small Modular Reactor (SMR) receives interests for the various application such as electricity co-generation, small-scale power generation, seawater desalination, district heating and propulsion. As a part of SMR development, supercritical CO2 Micro Modular Reactor (MMR) of 36.2MWth in power is under development by the KAIST research team. To enhance the mobility, the entire system including the power conversion system is designed for the full modularization. Based on the preliminary design, the thermal efficiency is 31.5% when CO2 is sufficiently cooled to the design temperature. A supercritical CO2 MMR is designed to supply electricity to the remote regions. The ambient temperature of the area can influence the compressor inlet temperature as the reactor is cooled with the atmospheric air. To estimate the S-CO2 cycle performance for various environmental conditions, A quasi-static analysis code is developed. For the off design performance of S-CO2 turbomachineries, the experimental result of Sandia National Lab (SNL) is utilized

  4. Performance power evaluation of DC fan cooling system for PV panel by using ANSYS CFX

    Science.gov (United States)

    Syafiqah, Z.; Amin, N. A. M.; Irwan, Y. M.; Irwanto, M.; Leow, W. Z.; Amelia, A. R.

    2017-09-01

    A research has been conducted to find the optimum combination for DC fan air cooling system of photovoltaic (PV) panel. During normal operation of PV panel, it is estimated that only 15 % of solar radiation is converted into electrical energy. Meanwhile, the rest of the solar radiation is converted into heat energy which affects the performance of the PV panel. Therefore, the aim of this research is to investigate the performance power evaluation of DC fan cooling system for PV panel by using ANSYS CFX. The effect of airflow configuration of DC fan has been investigated. This is to analyze whether the airflow circulation of DC fan cause a change towards the maximum temperature of PV panel. Besides, the impact of varying number of DC fans attached at the back of PV panel is evaluated. The result of airflow circulation of DC fan has been discussed. Meanwhile, with the increment number of DC fans, the PV panel temperature drops significantly. As a conclusion, the optimum number of DC fans is two with the combination of inlet airflow.

  5. Thermal performance of 2350 kW totally enclosed air to air cooled motor

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.C.; Kuo, S.C.; Chen, S.L. [National Taiwan Univ., Taipei, Taiwan (China). Dept. of Mechanical Engineering; Cheng, T.F. [TATUNG CO., Sanhsia, Taiwan (China)

    2009-07-01

    This study investigated numerically and experimentally the thermal performance of a 2350 kW enclosed air-to-air cooled motor. The experiment was divided into 2 sections. The centrifugal fans were tested using a standard test apparatus. Flow rates, output power, and pressure drop between the inlet and outlet were obtained. The motor was then tested to measure the flow rate of the external flow, and inlet and outlet temperatures of the external and internal flow in the heat exchanger. Motor performance was then simulated using a computational fluid dynamics (CFD) tool. Heat transfer within the motor was divided into external and internal flows. External flow was driven by the rotation of the centrifugal fan mounted to the frame on the motor shaft and passing through the tubes of a staggered heat exchanger mounted on the top of the frame. Internal flow was circulated through the heat exchanger by 2 axial fans located on either side of the rotor and cooled by the external flow. Axial and centrifugal fan simulations were in good agreement with results obtained during the experiments. The study demonstrated that the calculated velocity distributions of external flow fluids through the heat exchanger tubes are non-uniform. Air outlet temperatures for internal and external flows were estimated within 2 per cent. However, stator and rotor simulations were 3 per cent lower than experimental measured values. 7 refs., 1 tab., 15 figs.

  6. Effect of Wall Shear Stress on Corrosion Inhibitor Film Performance

    Science.gov (United States)

    Canto Maya, Christian M.

    In oil and gas production, internal corrosion of pipelines causes the highest incidence of recurring failures. Ensuring the integrity of ageing pipeline infrastructure is an increasingly important requirement. One of the most widely applied methods to reduce internal corrosion rates is the continuous injection of chemicals in very small quantities, called corrosion inhibitors. These chemical substances form thin films at the pipeline internal surface that reduce the magnitude of the cathodic and/or anodic reactions. However, the efficacy of such corrosion inhibitor films can be reduced by different factors such as multiphase flow, due to enhanced shear stress and mass transfer effects, loss of inhibitor due to adsorption on other interfaces such as solid particles, bubbles and droplets entrained by the bulk phase, and due to chemical interaction with other incompatible substances present in the stream. The first part of the present project investigated the electrochemical behavior of two organic corrosion inhibitors (a TOFA/DETA imidazolinium, and an alkylbenzyl dimethyl ammonium chloride), with and without an inorganic salt (sodium thiosulfate), and the resulting enhancement. The second part of the work explored the performance of corrosion inhibitor under multiphase (gas/liquid, solid/liquid) flow. The effect of gas/liquid multiphase flow was investigated using small and large scale apparatus. The small scale tests were conducted using a glass cell and a submersed jet impingement attachment with three different hydrodynamic patterns (water jet, CO 2 bubbles impact, and water vapor cavitation). The large scale experiments were conducted applying different flow loops (hilly terrain and standing slug systems). Measurements of weight loss, linear polarization resistance (LPR), and adsorption mass (using an electrochemical quartz crystal microbalance, EQCM) were used to quantify the effect of wall shear stress on the performance and integrity of corrosion inhibitor

  7. Spray cooling

    International Nuclear Information System (INIS)

    Rollin, Philippe.

    1975-01-01

    Spray cooling - using water spraying in air - is surveyed as a possible system for make-up (peak clipping in open circuit) or major cooling (in closed circuit) of the cooling water of the condensers in thermal power plants. Indications are given on the experiments made in France and the systems recently developed in USA, questions relating to performance, cost and environmental effects of spray devices are then dealt with [fr

  8. Performance analysis of ventilation systems with desiccant wheel cooling based on exergy destruction

    International Nuclear Information System (INIS)

    Tu, Rang; Liu, Xiao-Hua; Hwang, Yunho; Ma, Fei

    2016-01-01

    Highlights: • Ventilation systems with desiccant wheel were analyzed from exergy destruction. • Main performances influencing factors for ventilation systems are put forward. • Improved ventilation systems with lower exergy destruction are suggested. • Performances of heat pumps driven ventilation systems are greatly increased. - Abstract: This paper investigates the performances of ventilation systems with desiccant wheel cooling from the perspective of exergy destructions. Based on the inherent influencing factors for exergy destructions of heat and mass transfer and heat sources, provide guidelines for efficient system design. First, performances of a basic ventilation system are simulated, which is operated at high regeneration temperature and low coefficient of performance (COP). Then, exergy analysis of the basic ventilation system shows that exergy destructions mainly exist in the heat and mass transfer components and the heat source. The inherent influencing factors for the heat and mass transfer exergy destruction are heat and mass transfer capacities, which are related to over dehumidification of the desiccant wheel, and unmatched coefficients, which represent the uniformity of the temperature or humidity ratio differences fields for heat and mass transfer components. Based on these findings, two improved ventilation systems are suggested. For the first system, over dehumidification is avoided and unmatched coefficients for each component are reduced. With lower heat and mass transfer exergy destructions and lower regeneration temperature, COP and exergy efficiency of the first system are increased compared with the basic ventilation system. For the second system, a heat pump, which recovers heat from the process air to heat the regeneration air, is adopted to replace the electrical heater and cooling devices. The exergy destruction of the heat pump is considerably reduced as compared with heat source exergy destruction of the basic ventilation

  9. Development of the Glenn-HT Computer Code to Enable Time-Filtered Navier-Stokes (TFNS) Simulations and Application to Film Cooling on a Flat Plate Through Long Cooling Tubes

    Science.gov (United States)

    Ameri, Ali; Shyam, Vikram; Rigby, David; Poinsatte, Philip; Thurman, Douglas; Steinthorsson, Erlendur

    2014-01-01

    Computational fluid dynamics (CFD) analysis using Reynolds-averaged Navier-Stokes (RANS) formulation for turbomachinery-related flows has enabled improved engine component designs. RANS methodology has limitations which are related to its inability to accurately describe the spectrum of flow phenomena encountered in engines. Examples of flows that are difficult to compute accurately with RANS include phenomena such as laminarturbulent transition, turbulent mixing due to mixing of streams, and separated flows. Large eddy simulation (LES) can improve accuracy but at a considerably higher cost. In recent years, hybrid schemes which take advantage of both unsteady RANS and LES have been proposed. This study investigated an alternative scheme, the time-filtered Navier-Stokes (TFNS) method applied to compressible flows. The method developed by Shih and Liu was implemented in the Glenn-HT code and applied to film cooling flows. In this report the method and its implementation is briefly described. The film effectiveness results obtained for film cooling from a row of 30 holes with a pitch of 3.0 diameters emitting air at a nominal density ratio of unity and four blowing ratios of 0.5, 1.0, 1.5 and 2.0 are shown. Flow features under those conditions are also described.

  10. Development of the Glenn Heat-Transfer (Glenn-HT) Computer Code to Enable Time-Filtered Navier-Stokes (TFNS) Simulations and Application to Film Cooling on a Flat Plate Through Long Cooling Tubes

    Science.gov (United States)

    Ameri, Ali; Shyam, Vikram; Rigby, David; Poinsatte, Phillip; Thurman, Douglas; Steinthorsson, Erlendur

    2014-01-01

    Computational fluid dynamics (CFD) analysis using Reynolds-averaged Navier-Stokes (RANS) formulation for turbomachinery-related flows has enabled improved engine component designs. RANS methodology has limitations that are related to its inability to accurately describe the spectrum of flow phenomena encountered in engines. Examples of flows that are difficult to compute accurately with RANS include phenomena such as laminar/turbulent transition, turbulent mixing due to mixing of streams, and separated flows. Large eddy simulation (LES) can improve accuracy but at a considerably higher cost. In recent years, hybrid schemes that take advantage of both unsteady RANS and LES have been proposed. This study investigated an alternative scheme, the time-filtered Navier-Stokes (TFNS) method applied to compressible flows. The method developed by Shih and Liu was implemented in the Glenn-Heat-Transfer (Glenn-HT) code and applied to film-cooling flows. In this report the method and its implementation is briefly described. The film effectiveness results obtained for film cooling from a row of 30deg holes with a pitch of 3.0 diameters emitting air at a nominal density ratio of unity and two blowing ratios of 0.5 and 1.0 are shown. Flow features under those conditions are also described.

  11. Development of the Glenn-Heat-Transfer (Glenn-HT) Computer Code to Enable Time-Filtered Navier Stokes (TFNS) Simulations and Application to Film Cooling on a Flat Plate Through Long Cooling Tubes

    Science.gov (United States)

    Ameri, Ali A.; Shyam, Vikram; Rigby, David; Poinsatte, Phillip; Thurman, Douglas; Steinthorsson, Erlendur

    2014-01-01

    Computational fluid dynamics (CFD) analysis using Reynolds-averaged Navier-Stokes (RANS) formulation for turbomachinery-related flows has enabled improved engine component designs. RANS methodology has limitations that are related to its inability to accurately describe the spectrum of flow phenomena encountered in engines. Examples of flows that are difficult to compute accurately with RANS include phenomena such as laminar/turbulent transition, turbulent mixing due to mixing of streams, and separated flows. Large eddy simulation (LES) can improve accuracy but at a considerably higher cost. In recent years, hybrid schemes that take advantage of both unsteady RANS and LES have been proposed. This study investigated an alternative scheme, the time-filtered Navier-Stokes (TFNS) method applied to compressible flows. The method developed by Shih and Liu was implemented in the Glenn-Heat-Transfer (Glenn-HT) code and applied to film-cooling flows. In this report the method and its implementation is briefly described. The film effectiveness results obtained for film cooling from a row of 30deg holes with a pitch of 3.0 diameters emitting air at a nominal density ratio of unity and two blowing ratios of 0.5 and 1.0 are shown. Flow features under those conditions are also described.

  12. Sensitivity of energy and exergy performances of heating and cooling systems to auxiliary components

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2017-01-01

    . Different forms of energy (electricity and heat) are used in heating and cooling systems, and therefore, a holistic approach to system design and analysis is needed. In particular, distribution systems use electricity as a direct input to pumps and fans, and to other components. Therefore, exergy concept......Heating and cooling systems in buildings consist of three main subsystems: heating/cooling plant, distribution system, and indoor terminal unit. The choice of indoor terminal unit determines the characteristics of the distribution system and the heating and cooling plants that can be used...... should be used in design and analysis of the whole heating and cooling systems, in addition to the energy analysis. In this study, water-based (floor heating and cooling, and radiator heating) and air-based (air heating and cooling) heating and cooling systems were compared in terms of their energy use...

  13. Combination of Ultrasonic Vibration and Cryogenic Cooling for Cutting Performance Improvement of Inconel 718 Turning

    Science.gov (United States)

    Lin, S. Y.; Chung, C. T.; Cheng, Y. Y.

    2011-01-01

    The main objective of this study is to develop a thermo-elastic-plastic coupling model, based on a combination skill of ultrasonically assisted cutting and cryogenic cooling, under large deformation for Inconel 718 alloy machining process. The improvement extent on cutting performance and tool life promotion may be examined from this investigation. The critical value of the strain energy density of the workpiece will be utilized as the chip separation and the discontinuous chip segmentation criteria. The forced convection cooling and a hydrodynamic lubrication model will be considered and formulated in the model. Finite element method will be applied to create a complete numerical solution for this ultrasonic vibration cutting model. During the analysis, the cutting tool is incrementally advanced forward with superimposed ultrasonic vibration in a back and forth step-by-step manner, from an incipient stage of tool-workpiece engagement to a steady state of chip formation, a whole simulation of orthogonal cutting process under plane strain deformation is thus undertaken. High shear strength induces a fluctuation phenomenon of shear angle, high shear strain rate, variation of chip types and chip morphology, tool-chip contact length variation, the temperature distributions within the workpiece, chip and tool, periodic fluctuation in cutting forces can be determined from the developed model. A complete comparison of machining characteristics between some different combinations of ultrasonically assisted cutting and cryogenic cooling with conventional cutting operation can be acquired. Finally, the high-speed turning experiment for Inconel 718 alloy will be taken in the laboratory to validate the accuracy of the model, and the progressive flank wear, crater wear, notching and chipping of the tool edge can also be measured in the experiments.

  14. Absorption of water vapour in the falling film of water-(LiBr + LiI + LiNO{sub 3} + LiCl) in a vertical tube at air-cooling thermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bourouis, Mahmoud; Valles, Manel; Medrano, Marc; Coronas, Alberto [Centro de Innovacion Tecnologica en Revalorizacion Energetica y Refrigeracion, CREVER, Universitat Rovira i Virgili, Autovia de Salou, s/n, 43006, Tarragona (Spain)

    2005-05-01

    In air-cooled water-LiBr absorption chillers the working conditions in the absorber and condenser are shifted to higher temperatures and concentrations, thereby increasing the risk of crystallisation. To develop this technology, two main problems are to be addressed: the availability of new salt mixtures with wider range of solubility than water-LiBr, and advanced absorber configurations that enable to carry out simultaneously an appropriate absorption process and an effective air-cooling. One way of improving the solubility of LiBr aqueous solutions is to add other salts to create multicomponent salt solutions. The aqueous solution of the quaternary salt system (LiBr + LiI + LiNO{sub 3} + LiCl) presents favourable properties required for air-cooled absorption systems: less corrosive and crystallisation temperature about 35 K lower than that of water-LiBr.This paper presents an experimental study on the absorption of water vapour over a wavy laminar falling film of an aqueous solution of (LiBr + LiI + LiNO{sub 3} + LiCl) on the inner wall of a water-cooled smooth vertical tube. Cooling water temperatures in the range 30-45 C were selected to simulate air-cooling thermal conditions. The results are compared with those obtained in the same experimental set-up with water-LiBr solutions.The control variables for the experimental study were: absorber pressure, solution Reynolds number, solution concentration and cooling water temperature. The parameters considered to assess the absorber performance were: absorber thermal load, mass absorption flux, degree of subcooling of the solution leaving the absorber, and the falling film heat transfer coefficient.The higher solubility of the multicomponent salt solution makes possible the operation of the absorber at higher salt concentration than with the conventional working fluid water-LiBr. The absorption fluxes achieved with water-(LiBr + LiI + LiNO{sub 3} + LiCl) at a concentration of 64.2 wt% are around 60 % higher than

  15. Performance of metal and oxide fuels during accidents in a large liquid metal cooled reactor

    International Nuclear Information System (INIS)

    Cahalan, J.; Wigeland, R.; Friedel, G.; Kussmaul, G.; Royl, P.; Moreau, J.; Perks, M.

    1990-01-01

    In a cooperative effort among European and US analysts, an assessment of the comparative safety performance of metal and oxide fuels during accidents in a large (3500 MWt), pool-type, liquid-metal-cooled reactor (LMR) was performed. The study focused on three accident initiators with failure to scram: the unprotected loss-of-flow (ULOF), the unprotected transient overpower (UTOP), and the unprotected loss-of-heat-sink (ULOHS). Emphasis was placed on identification of design features that provide passive, self-limiting responses to upset conditions, and quantification of relative safety margins. The analyses show that in ULOF and ULOHS sequences, metal-fueled LMRs with pool-type primary systems provide larger temperature margins to coolant boiling than oxide-fueled reactors of the same design. 3 refs., 4 figs

  16. On the performance of air conditioner with heat pipe for cooling air in the condenser

    Energy Technology Data Exchange (ETDEWEB)

    Naphon, Paisarn, E-mail: paisarnn@swu.ac.t [Thermo-Fluids and Heat Transfer Enhancement Laboratory (TFHT), Department of Mechanical Engineering, Faculty of Engineering, Srinakharinwirot University, 63 Rangsit-Nakhornnayok Rd., Ongkharak, Nakhorn-Nayok 26120 (Thailand)

    2010-11-15

    Improvement of the air conditioning system performance by using the heat pipe for cooling air before entering the condenser is presented. In the experiment, the heat pipe is fabricated from the straight copper tube with the diameter and length of 10, 600 mm, respectively. The arrangements of the heat pipe sets are arranged in the staggered layout with the tube rows of 1, 2, 3. R134a refrigerant is used as working fluid in the heat pipe set for this present study. By comparing with a conventional air conditioning system, the air conditioning system with three rows of heat pipe gives the highest COP and EER with increasing of 6.4%, 17.5%, respectively. On the global warming and environment problems, the results of this study are expected to lead to guidelines that will allow the improved performance of the air conditioning systems which reduce its energy consumption.

  17. On the performance of air conditioner with heat pipe for cooling air in the condenser

    International Nuclear Information System (INIS)

    Naphon, Paisarn

    2010-01-01

    Improvement of the air conditioning system performance by using the heat pipe for cooling air before entering the condenser is presented. In the experiment, the heat pipe is fabricated from the straight copper tube with the diameter and length of 10, 600 mm, respectively. The arrangements of the heat pipe sets are arranged in the staggered layout with the tube rows of 1, 2, 3. R134a refrigerant is used as working fluid in the heat pipe set for this present study. By comparing with a conventional air conditioning system, the air conditioning system with three rows of heat pipe gives the highest COP and EER with increasing of 6.4%, 17.5%, respectively. On the global warming and environment problems, the results of this study are expected to lead to guidelines that will allow the improved performance of the air conditioning systems which reduce its energy consumption.

  18. Passive containment cooling system performance in the simplified boiling water reactor

    International Nuclear Information System (INIS)

    Shiralkar, B.S.; Gamble, R.E.; Yadigaroglu, G.

    1997-01-01

    The Simplified Boiling Water Reactor (SBWR) incorporates a passive system for decay heat removal from the containment in the event of a postulated Loss-of-Coolant Accident (LOCA). Decay heat is removed by condensation of the steam discharged from the reactor pressure vessel (RPV) in three condensers which comprise the Passive Containment Cooling System (PCCS). These condensers are designed to carry the heat load while transporting a mixture of steam and noncondensible gas (primarily nitrogen) from the drywell to the suppression chamber. This paper describes the expected LOCA response of the SBWR with respect to the PCCS performance, based on analysis and test results. The results confirm that the PCCS has excess capacity for decay heat removal and that overall system performance is very robust. 12 refs., 8 figs

  19. The performance of a temperature cascaded cogeneration system producing steam, cooling and dehumidification

    KAUST Repository

    Myat, Aung

    2013-02-01

    This paper discusses the performance of a temperature-cascaded cogeneration plant (TCCP), equipped with an efficient waste heat recovery system. The TCCP, also called a cogeneration system, produces four types of useful energy-namely, (i) electricity, (ii) steam, (iii) cooling and (iv) dehumidification-by utilizing single fuel source. The TCCP comprises a Capstone C-30 micro-turbine that generates nominal capacity of 26 kW of electricity, a compact and efficient waste heat recovery system and a host of waste-heat-activated devices, namely (i) a steam generator, (ii) an absorption chiller, (iii) an adsorption chiller and (iv) a multi-bed desiccant dehumidifier. The performance analysis was conducted under different operation conditions such as different exhaust gas temperatures. It was observed that energy utilization factor could be as high as 70% while fuel energy saving ratio was found to be 28%. © 2013 Desalination Publications.

  20. Performance of an optimally contact-cooled high-heat-load mirror at the APS

    International Nuclear Information System (INIS)

    Cai, Z.; Khounsary, A.; Lai, B.; McNulty, I.; Yun, W.

    1998-01-01

    X-ray undulator beamlines at third-generation synchrotrons facilities use either a monochromator or a mirror as the first optical element. In this paper, the thermal and optical performance of an optimally designed contact-cooled high-heat-load x-ray mirror used as the first optical element on the 2ID undulator beamline at the Advanced Photon Source (APS) is reported. It is shown that this simple and economical mirror design can comfortably handle the high heat load of undulator beamlines and provide good performance with long-term reliability and ease of operation. Availability and advantages of such mirrors can make the mirror-first approach to high-heat-load beamline design an attractive alternative to monochromator-first beamlines in many circumstances

  1. System performance and economic analysis of solar-assisted cooling/heating system

    KAUST Repository

    Huang, B.J.; Wu, J.H.; Yen, R.H.; Wang, J.H.; Hsu, H.Y.; Hsia, C.J.; Yen, C.W.; Chang, J.M.

    2011-01-01

    The long-term system simulation and economic analysis of solar-assisted cooling/heating system (SACH-2) was carried out in order to find an economical design. The solar heat driven ejector cooling system (ECS) is used to provide part of the cooling

  2. Cool products for building envelope - Part II: Experimental and numerical evaluation of thermal performances

    NARCIS (Netherlands)

    Revel, G.M.; Martarelli, M.; Emiliani, M.; Celotti, L.; Nadalini, R.; Ferrari, A.D.; Hermanns, S.; Beckers, E.

    2014-01-01

    Cool materials have a large potential as cost-effective solution for reducing cooling energy consumption in hot summer and mild winter regions like Mediterranean countries. A previous paper has described in detail the development of cool coloured ceramic tiles, acrylic paints and bituminous

  3. EFFECT OF THE FILL VENTILATION WINDOW ON PERFORMANCE OF A NATURAL DRAFT COOLING TOWER SUBJECTED TO CROSS-WINDS

    Directory of Open Access Journals (Sweden)

    K. V. Dobrego

    2016-01-01

    Full Text Available Various aerodynamic design elements and technics (wind deflectors, wind walls, etc. are utilized for improvement of the thermal efficiency of the natural draft cooling towers, particularly in conditions of cross wind. One of the technical methods, proposed by engineers of Belarus Academy of Sciences, is installation of the ventilation window in the center of the fill. This method is substantiated by the fact that the flow of cooling gas obtains maximum temperature and humidity near the center of the under-fill space of cooling tower and, as a consequence, performs minimal heat exchange. The influence of the fill ventilation window and wind deflectors in the inlet windows of the cooling tower on its thermal performance in condition of cross-wind is investigated in the paper numerically. The cooling tower of the “Woo-Jin” power plant (China 150 m of the height and 114 m of the base diameter was taken as a prototype. The analogy (equivalence between the heat and mass transfer was taken into consideration, which enabled us to consider single-phase flow and perform complicated 3D simulation by using modern personal computers. Heat transfer coefficient for the fill and its hydrodynamic resistance were defined by using actual data on total flow rate in the cooling tower. The numerical model and computational methods were tested and verified in numerous previous works. The non-linear dependence of the thermal performance of the cooling tower on wind velocity (with the minimum in vicinity of Ucr ~ 8 m/s for the simulated system was demonstrated. Calculations show that in the condition of the average wind speed the fill ventilation window doesn’t improve, but slightly decrease (by 3–7 % performance of the cooling tower. Situation changes in the condition of strong winds Ucw > 12 m/s, which are not typical for Belarus. Utilization of airflow deflectors at the inlet windows of cooling tower, conversely, increases thermal performance of the

  4. Dynamic behavior of radiant cooling system based on capillary tubes in walls made of high performance concrete

    DEFF Research Database (Denmark)

    Mikeska, Tomás; Svendsen, Svend

    2015-01-01

    elements made of high performance concrete. The influence of the radiant cooling system on the indoor climate of the test room in terms of the air, surface and operative temperatures and velocities was investigated.The results show that the temperature of the room air can be kept in a comfortable range...... using cooling water for the radiant cooling system with a temperature only about 4K lower than the temperature of the room air. The relatively high speed reaction of the designed system is a result of the slim construction of the sandwich wall elements made of high performance concrete. (C) 2015...... the small amount of fresh air required by standards to provide a healthy indoor environment.This paper reports on experimental analyses evaluating the dynamic behavior of a test room equipped with a radiant cooling system composed of plastic capillary tubes integrated into the inner layer of sandwich wall...

  5. The performance of a mobile air conditioning system with a water cooled condenser

    International Nuclear Information System (INIS)

    Di Battista, Davide; Cipollone, Roberto

    2015-01-01

    Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels.In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase. (paper)

  6. Cooling tower performance improvements for a cycling PC-fired unit

    International Nuclear Information System (INIS)

    Keckritz, M.; Thelen, A.

    1997-01-01

    The inevitable deregulation of the electric utility industry has caused many electric utility companies to look closely at their existing assets and predict what role these units will play in the future. Reducing a unit's production cost is the best way to prepare for the deregulated market but this benefit often comes with an associated capital expenditure. Spending capital dollars today can pose a quandary for an investor-owned utility committed to maintaining low consumer rates. The dilemma is: How does a utility improve its competitiveness position today while ensuring that the shareholders are getting a fair return on their investment when any fuel savings are passed through to the consumer? Illinois Power (IP) has been aggressively looking to improve their current competitive position while facing the current regulatory challenges. Studies have been commissioned to identify the most attractive cost reduction opportunities available. One study identified that improving the performance of the Unit 6 cooling tower at the Havana Station would be a very economically attractive option. This paper addresses the economics of refurbishing a cooling tower for a cycling pulverized-coal (PC) unit to provide a competitive advantage leading into the deregulated electricity market

  7. Improved energy performance of air cooled centrifugal chillers with variable chilled water flow

    International Nuclear Information System (INIS)

    Yu, F.W.; Chan, K.T.

    2008-01-01

    This paper considers how to apply optimum condensing temperature control and variable chilled water flow to increase the coefficient of performance (COP) of air cooled centrifugal chillers. A thermodynamic model for the chillers was developed and validated using a wide range of operating data and specifications. The model considers real process phenomena, including capacity control by the inlet guide vanes of the compressor and an algorithm to determine the number and speed of condenser fans staged based on a set point of condensing temperature. Based on the validated model, it was found that optimizing the control of condensing temperature and varying the evaporator's chilled water flow rate enable the COP to increase by 0.8-191.7%, depending on the load and ambient conditions. A cooling load profile of an office building in a subtropical climate was considered to assess the potential electricity savings resulting from the increased chiller COP and optimum staging of chillers and pumps. There is 16.3-21.0% reduction in the annual electricity consumption of the building's chiller plant. The results of this paper provide useful information on how to implement a low energy chiller plant

  8. The performance of a mobile air conditioning system with a water cooled condenser

    Science.gov (United States)

    Di Battista, Davide; Cipollone, Roberto

    2015-11-01

    Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels. In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase.

  9. Single-layer nano-carbon film, diamond film, and diamond/nano-carbon composite film field emission performance comparison

    International Nuclear Information System (INIS)

    Wang, Xiaoping; Wang, Jinye; Wang, Lijun

    2016-01-01

    A series of single-layer nano-carbon (SNC) films, diamond films, and diamond/nano-carbon (D/NC) composite films have been prepared on the highly doped silicon substrate by using microwave plasma chemical vapor deposition techniques. The films were characterised by scanning electron microscopy, Raman spectroscopy, and field emission I-V measurements. The experimental results indicated that the field emission maximum current density of D/NC composite films is 11.8–17.8 times that of diamond films. And the field emission current density of D/NC composite films is 2.9–5 times that of SNC films at an electric field of 3.0 V/μm. At the same time, the D/NC composite film exhibits the advantage of improved reproducibility and long term stability (both of the nano-carbon film within the D/NC composite cathode and the SNC cathode were prepared under the same experimental conditions). And for the D/NC composite sample, a high current density of 10 mA/cm"2 at an electric field of 3.0 V/μm was obtained. Diamond layer can effectively improve the field emission characteristics of nano-carbon film. The reason may be due to the diamond film acts as the electron acceleration layer.

  10. Numerical and experimental analysis of a thin liquid film on a rotating disk related to development of a spacecraft absorption cooling system

    Science.gov (United States)

    Faghri, Amir; Swanson, Theodore D.

    1989-01-01

    The numerical and experimental analysis of a thin liquid film on a rotating and a stationary disk related to the development of an absorber unit for a high capacity spacecraft absorption cooling system, is described. The creation of artificial gravity by the use of a centrifugal field was focused upon in this report. Areas covered include: (1) One-dimensional computation of thin liquid film flows; (2) Experimental measurement of film height and visualization of flow; (3) Two-dimensional computation of the free surface flow of a thin liquid film using a pressure optimization method; (4) Computation of heat transfer in two-dimensional thin film flow; (5) Development of a new computational methodology for the free surface flows using a permeable wall; (6) Analysis of fluid flow and heat transfer in a thin film in the presence and absence of gravity; and (7) Comparison of theoretical prediction and experimental data. The basic phenomena related to fluid flow and heat transfer on rotating systems reported here can also be applied to other areas of space systems.

  11. Graphite-modified cooling ceiling. A comparative evaluation of the performance; Graphitmodifizierte Kuehldecken. Eine vergleichende Bewertung zur Leistungsfaehigkeit

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, Gerd [Technische Univ. Muenchen (Germany); Fraunhofer-Institut fuer Bauphysik, Stuttgart (Germany); Hausladen, Gerhard [Technische Univ. Muenchen (Germany); Ingenieurbuero Hausladen GmbH, Muenchen (Germany); Jacobsen, Cornelia; Hutter, Christina; Hanusch, Christoph [Ingenieurbuero Hausladen GmbH, Muenchen (Germany); Schlitzberger, Stephan [Ingenieurbuero fuer Bauphysik Prof. Dr. Hauser GmbH, Kassel (Germany)

    2013-03-01

    In most cases, the utilization of graphite-modified building materials enhances their thermal conductivity. Thus, chilled ceiling systems achieve an enhanced thermal absorption in comparison to commercial chilled ceiling systems. For this, a simulation for the estimation of the thermal comfort as well as for the quantification of the impacts on the demand of electricity for the refrigeration is performed. The enhanced cooling capacity of the graphite-modified cooling ceiling 'Ecophit' affects the operation positively.

  12. Numerical study of the thermo-flow performances of novel finned tubes for air-cooled condensers in power plant

    Science.gov (United States)

    Guo, Yonghong; Du, Xiaoze; Yang, Lijun

    2018-02-01

    Air-cooled condenser is the main equipment of the direct dry cooling system in a power plant, which rejects heat of the exhaust steam with the finned tube bundles. Therefore, the thermo-flow performances of the finned tubes have an important effect on the optimal operation of the direct dry cooling system. In this paper, the flow and heat transfer characteristics of the single row finned tubes with the conventional flat fins and novel jagged fins are investigated by numerical method. The flow and temperature fields of cooling air for the finned tubes are obtained. Moreover, the variations of the flow resistance and average convection heat transfer coefficient under different frontal velocity of air and jag number are presented. Finally, the correlating equations of the friction factor and Nusselt number versus the Reynolds number are fitted. The results show that with increasing the frontal velocity of air, the heat transfer performances of the finned tubes are enhanced but the pressure drop will increase accordingly, resulting in the average convection heat transfer coefficient and friction factor increasing. Meanwhile, with increasing the number of fin jag, the heat transfer performance is intensified. The present studies provide a reference in optimal designing for the air-cooled condenser of direct air cooling system.

  13. Experimental study on the performance of a liquid cooling garment with the application of MEPCMS

    International Nuclear Information System (INIS)

    Wang, Tao; Wang, Liang; Bai, Lizhan; Lin, Guiping; Bu, Xueqin; Liu, Xiangyang; Xie, Guanghui

    2015-01-01

    Highlights: • MEPCMS was applied in a liquid cooling garment for space applications. • Extensive experimental study on the performance of the LCG was conducted. • LCG was assessed by heat dissipation, temperature control and thermal comfort. • Proper match of relevant parameters was crucial in enhancing LCG performance. • 26% enhancement in heat dissipation was achieved by MEPCMS compared to water. - Abstract: As a novel working fluid, microencapsulated phase change material suspension (MEPCMS) exhibits obvious superiority in both heat transfer and temperature control compared with traditional ones. In this paper, extensive experimental study on the performance of a liquid cooling garment (LCG) with the application of this novel working fluid was conducted for future space applications. The main task for a LCG is to efficiently collect, transport and dissipate the metabolic heat produced from the human body. In the experiment, a thermal manikin was employed to simulate the human body, and the performance of the LCG with MEPCMS as the working fluid was evaluated by a variety of aspects such as heat dissipation, temperature control, pump power consumption and thermal comfort under both steady state and transient conditions. Experimental results show that the inlet temperature, mass flowrate and volume concentration of the MEPCMS are three key parameters affecting the performance of the LCG, which can be enhanced significantly by a proper combination of these parameters. Otherwise, the performance of the LCG will deteriorate or even be worse than that using water as the working fluid. When the inlet temperature, mass flowrate and volume concentration of the MEPCMS were selected as 11 °C, 200 g/min and 20% respectively, the heat dissipation of the LCG was enhanced by up to 26% with no obvious increase of the pump power compared with that using water as the working fluid, the temperature distribution in the human body became more uniform, and the capability

  14. Deposition of tellurium films by decomposition of electrochemically-generated H{sub 2}Te: application to radiative cooling devices

    Energy Technology Data Exchange (ETDEWEB)

    Engelhard, T.; Jones, E.D.; Viney, I. [Coventry Univ. (United Kingdom). Centre for Data Storage Mater.; Mastai, Y.; Hodes, G. [Department of Materials and Interfaces, Weizmann Institute of Science, 76100, Rehovot (Israel)

    2000-07-17

    The preparation of homogenous, large area thin layers of tellurium on thin polyethylene foils is described. The tellurium was formed by room temperature decomposition of electrochemically generated H{sub 2}Te. Pre-treatment of the polyethylene substrates with KMnO{sub 4} to give a Mn-oxide layer was found to improve the Te adhesion and homogeneity. Optical characterization of the layers was performed using UV/VIS/NIR spectroscopy. Such coatings have favorable characteristics for use as solar radiation shields in radiative cooling devices. The simplicity of generation of the very unstable H{sub 2}Te was also exploited to demonstrate formation of size-quantized CdTe nanocrystals. (orig.)

  15. Controllable film densification and interface flatness for high-performance amorphous indium oxide based thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ou-Yang, Wei, E-mail: OUYANG.Wei@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Kizu, Takio; Gao, Xu; Lin, Meng-Fang; Tsukagoshi, Kazuhito, E-mail: OUYANG.Wei@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp [International Center for Materials Nanoarchitectronics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Nabatame, Toshihide [MANA Foundry and MANA Advanced Device Materials Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-10-20

    To avoid the problem of air sensitive and wet-etched Zn and/or Ga contained amorphous oxide transistors, we propose an alternative amorphous semiconductor of indium silicon tungsten oxide as the channel material for thin film transistors. In this study, we employ the material to reveal the relation between the active thin film and the transistor performance with aid of x-ray reflectivity study. By adjusting the pre-annealing temperature, we find that the film densification and interface flatness between the film and gate insulator are crucial for achieving controllable high-performance transistors. The material and findings in the study are believed helpful for realizing controllable high-performance stable transistors.

  16. Post-LOCA long term cooling performance in Korean standard nuclear power plants

    International Nuclear Information System (INIS)

    Bang, Young Seok; Jung, Jae Won; Seul, Kwang Won; Kim, Hho Jung

    1999-01-01

    The post-LOCA long term cooling (LTC) performance of the Korean Standard Nuclear Power Plant (KSNPP) is analyzed for both small break LOCA and large break LOCA. The RELAP5/MOD3.2.2 code is used to calculate the LTC sequences based on the LTC plan of the KSNPP. A standard input model is developed such that LOCA and the followed LTC sequence can be calculated in a single run for both small break LOCA and large break LOCA. A spectrum of small break LOCA ranging from 0.02 to 0.5 ft 2 of break area and a double-ended guillotine break are analyzed. Through the code calculations, the thermal-hydraulic behavior and the boron behavior are evaluated and the effect of the important manual action including the safety injection tank isolation in LTC procedure is investigated

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

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1981-01-01

    The performance of steam generator tubes in water-cooled nuclear power reactors is reviewed for 1979. Tube failures occurred at 38 of the 93 reactors surveyed. The causes of these failures and the procedures designed to deal with them are described. The defect rate, although higher than that in 1978, was still lower than the rates of the two previous years. Methods being employed to detect defects include the increased use of multifrequency eddy-current testing and a trend to full-length inspection of all tubes. To reduce the incidence of tube failure by corrosion, plant operators are turning to full-flow condensate demineralization and more leak-resistant condenser tubes. 10 tables

  18. Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

    International Nuclear Information System (INIS)

    Khun, N.W.; Liu, E.

    2011-01-01

    Research highlights: → Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. → The graphitization of the films increased with increased film thickness. → The wear resistance of the films increased though their adhesion strength decreased. → The corrosion potentials of the films shifted to more negative values. → However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp 2 bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

  19. Study on Gas Sensing Performance of TiO2 Screen Printed Thick Films

    Directory of Open Access Journals (Sweden)

    C. G. DIGHAVKAR

    2009-02-01

    Full Text Available Titanium dioxide (TiO2 thick films were prepared on alumina substrate by using screen printing technique. After preparation, the films were fired at temperature range 600 -1000 ºC for two hour. Morphological, compositional and structural properties of the film samples were performed by means of several techniques, including scanning electron microscopy (SEM, Energy dispersive spectroscopy (EDS, X-ray diffraction techniques. We explore the various gases to study the sensing performance of the TiO2 thick films. The maximum response was reported to film fired at 800 0C for LPG gas at 350 0C operating temperature.

  20. Effect of performance of Zr-Y alloy target on thin film deposition technology

    International Nuclear Information System (INIS)

    Pan Qianfu; Liu Chaohong; Jiang Mingzhong; Yin Changgeng

    2011-01-01

    Yttria-stabilized zirconia (YSZ) films are synthesized on corrosion resistant plates by pulsed bias arc ion plating. The arc starting performance and the stability of thin film deposition is explored by improving the uniformity and compactibility of Zr-Y alloy target. The property of Zr-Y alloy target and depositional thin films were measured with the optical microscope, scanning electron microscope, X-ray diffractometer. The result shows that the target with hot rolling and annealing has a good arc starting performance and stability of thin film deposition, and the depositional thin films made of Yttria and amorphous zirconia are homogeneous and compact. (authors)

  1. Effects of ejector geometries on performance of ejector-expansion R410A air conditioner considering cooling seasonal performance factor

    International Nuclear Information System (INIS)

    Jeon, Yongseok; Jung, Jongho; Kim, Dongwoo; Kim, Sunjae; Kim, Yongchan

    2017-01-01

    Highlights: •The performance of an ejector-expansion R410A air conditioner is measured. •The effect of ejector geometries on the COP and CSPF is analyzed. •The mixing-section diameter of the ejector is optimized based on the CSPF. •The mixing-section diameter is optimized based on the climatic conditions. -- Abstract: The objective of this study was to investigate the effects of ejector geometries on the performance of an ejector-expansion air conditioner (EEAC) considering the cooling seasonal performance factor (CSPF). The performance of the EEAC using R410A was measured and analyzed by varying the compressor speed, outdoor-bin temperature, operating pressures, nozzle-throat diameter, and mixing-section diameter. The EEAC in the medium-capacity mode exhibited maximum coefficient of performance (COP) improvement, i.e., 7.5%, over the baseline (conventional) cycle. The optimum mixing-section diameter was determined to be 9 mm based on the CSPF. In addition, the optimum mixing-section diameter increased with an increase in the annual average outdoor temperature. The CSPF of the EEAC with the optimized mixing-section diameter improved in the range of 16.0–20.3% over the baseline cycle depending on the climatic conditions.

  2. Experimental investigation of pulsating heat pipe performance with regard to fuel cell cooling application

    International Nuclear Information System (INIS)

    Clement, Jason; Wang Xia

    2013-01-01

    A pulsating heat pipe (PHP) is a closed loop, passive heat transfer device. Its operation depends on the phase change of a working fluid within the loop. Design and performance testing of a pulsating heat pipe was conducted under conditions to simulate heat dissipation requirements of a proton exchange membrane (PEM) fuel cell stack. Integration of pulsating heat pipes within bipolar plates of the stack would eliminate the need for ancillary cooling equipment, thus also reducing parasitic losses and increasing energy output. The PHP under investigation, having dimensions of 46.80 cm long and 14.70 cm wide, was constructed from 0.3175 cm copper tube. Heat pipes effectiveness was found to be dependent upon several factors such as energy input, types of working fluid and its filling ratio. Power inputs to the evaporator side of the pulsating heat pipe varied from 80 to 180 W. Working fluids tested included acetone, methanol, and deionized water. Filling ratios between 30 and 70 percent of the total working volume were also examined. Methanol outperformed other fluids tested; with a 45 percent fluid fill ratio and a 120 W power input, the apparatus took the shortest time to reach steady state and had one of the smallest steady state temperature differences. The various conditions studied were chosen to assess the heat pipe's potential as cooling media for PEM fuel cells. - Highlights: ► Methanol as a working fluid outperformed both acetone and water in a pulsating heat pipe. ► Performance for the PHP peaked with methanol and a fill ratio of 45 percent fluid to total volume. ► A smaller resistance was associated with a higher power input to the system.

  3. Heat removal performance of auxiliary cooling system for the high temperature engineering test reactor during scrams

    International Nuclear Information System (INIS)

    Takeda, Takeshi; Tachibana, Yukio; Iyoku, Tatsuo; Takenaka, Satsuki

    2003-01-01

    The auxiliary cooling system of the high temperature engineering test reactor (HTTR) is employed for heat removal as an engineered safety feature when the reactor scrams in an accident when forced circulation can cool the core. The HTTR is the first high temperature gas-cooled reactor in Japan with reactor outlet gas temperature of 950 degree sign C and thermal power of 30 MW. The auxiliary cooling system should cool the core continuously avoiding excessive cold shock to core graphite components and water boiling of itself. Simulation tests on manual trip from 9 MW operation and on loss of off-site electric power from 15 MW operation were carried out in the rise-to-power test up to 20 MW of the HTTR. Heat removal characteristics of the auxiliary cooling system were examined by the tests. Empirical correlations of overall heat transfer coefficients were acquired for a helium/water heat exchanger and air cooler for the auxiliary cooling system. Temperatures of fluids in the auxiliary cooling system were predicted on a scram event from 30 MW operation at 950 degree sign C of the reactor outlet coolant temperature. Under the predicted helium condition of the auxiliary cooling system, integrity of fuel blocks among the core graphite components was investigated by stress analysis. Evaluation results showed that overcooling to the core graphite components and boiling of water in the auxiliary cooling system should be prevented where open area condition of louvers in the air cooler is the full open

  4. Materials Performance in Sodium-Cooled Fast Reactors: Past, Present, and Future

    International Nuclear Information System (INIS)

    Natesan, K.; Li Meimei

    2013-01-01

    • This paper gives an overview of the requirements, selection, and performance of materials for in-core and out-of-core components in SFRs. • Globally, sodium-cooled fast reactors have been designed, built, and operated in several countries. A substantial database exists for the existing materials on their functional and mechanical performance. • The 60-yr design life of the SFR presents a significant challenge to the development of database, extrapolation/prediction of long-term performance, and high-temperature design methodology for the structural components. • Licensing of SFR requires a valid assessment of the environmental effects (irradiation, thermal aging, and sodium) on materials performance. • Advanced materials such as, ODS alloys for cladding, Gr91 and 92 F/M steels, and austenitic alloys such as NF709 for structures can improve the economy, safety, and flexibility of SFRs. A substantial database is needed for all these materials and global effort is underway to develop the needed information through experimentation and modeling

  5. Performance of water cooled nuclear power reactor fuels in India – Defects, failures and their mitigation

    International Nuclear Information System (INIS)

    Ganguly, Chaitanyamoy

    2015-01-01

    Water cooled and moderated nuclear power reactors account for more than 95% of the operating reactors in the world today. Light water reactors (LWRs) consisting of pressurized water reactor (PWR), their Russian counterpart namely VVER and boiling water reactor (BWR) will continue to dominate the nuclear power market. Pressurized heavy water reactor (PHWR), also known as CANDU, is the backbone of the nuclear power program in India. Updates on LWR and PHWR fuel performance are being periodically published by IAEA, OECD-NEA and the World Nuclear Association (WNA), highlighting fuel failure rate and the mitigation of fuel defects and failures. These reports clearly indicate that there has been significant improvement in in – pile fuel performance over the years and the present focus is to achieve zero fuel failure in high burn up and high performance fuels. The present paper summarizes the status of PHWR and LWR fuel performance in India, highlighting the manufacturing and the related quality control and inspection steps that are being followed at the PHWR fuel fabrication plant in order to achieve zero manufacturing defect which could contribute to achieving zero in – pile failure rate in operating and upcoming PHWR units in India. (author)

  6. Thermal Performance for Wet Cooling Tower with Different Layout Patterns of Fillings under Typical Crosswind Conditions

    Directory of Open Access Journals (Sweden)

    Ming Gao

    2017-01-01

    Full Text Available A thermal-state model experimental study was performed in lab to investigate the thermal performance of a wet cooling tower with different kinds of filling layout patterns under windless and 0.4 m/s crosswind conditions. In this paper, the contrast analysis was focused on comparing a uniform layout pattern and one kind of optimal non-uniform layout pattern when the environmental crosswind speed is 0 m/s and 0.4 m/s. The experimental results proved that under windless conditions, the heat transfer coefficient and total heat rejection of circulating water for the optimal non-uniform layout pattern can enhance by approximately 40% and 28%, respectively, compared with the uniform layout pattern. It was also discovered that the optimal non-uniform pattern can dramatically relieve the influence of crosswind on the thermal performance of the tower when the crosswind speed is equal to 0.4 m/s. For the uniform layout pattern, the heat transfer coefficient under 0.4 m/s crosswind conditions decreased by 9.5% compared with the windless conditions, while that value lowered only by 2.0% for the optimal non-uniform layout pattern. It has been demonstrated that the optimal non-uniform layout pattern has the better thermal performance under 0.4 m/s crosswind condition.

  7. Performance Analysis of a Multiple Micro-Jet Impingements Cooling Model

    Directory of Open Access Journals (Sweden)

    A. Husain

    2016-06-01

    Full Text Available The present study investigates the thermal performance of a multiple micro-jet impingements model for electronics cooling. The fluid flow and heat transport characteristics were investigated for steady incompressible laminar flow by solving three-dimensional (3D Navier-Stokes equations. Several parallel and staggered micro-jet configurations (ie. inline 2 Å~ 2, 3 Å~ 3 and 4 Å~ 4 jets, and staggered five-jet and 13-jet arrays with the jet diameter to the channel height ratios from 0.25–0.5 were analyzed at various flow rates for the maximum temperature rise, pressure drop, heat-transfer coefficient, thermal resistance, and pumping power characteristics. The parametric investigation was carried out based on the number of jets and the jet diameters at various mass flow rates and jet Reynolds numbers. Temperature uniformity and coefficient of performance were evaluated to find out the trade-off among the various designs investigated in the present study. The maximum temperature rise and the pressure drop decreased with an increase in the number of jets except in the case of staggered five-jet array. A higher temperature uniformity was observed at higher flow rates with a decrease in the coefficient of performance. The performance parameters, such as thermal resistance and pumping power, showed a conflicting nature with respect to design variables (viz. jet diameter to stand-off ratio and interjet spacing or number of jets at various Reynolds numbers within the laminar regime.

  8. Radiative cooling test facility and performance evaluation of 4-MIL aluminized polyvinyl fluoride and white-paint surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kruskopf, M.S.; Berdahl, P.; Martin, M.; Sakkal, F.; Sobolewski, M.

    1980-11-01

    A test facility designed to measure the amount of radiative cooling a specific material or assembly of materials will produce when exposed to the sky is described. Emphasis is placed upon assemblies which are specifically designed to produce radiative cooling and which therefore offer promise for the reduction of temperatures and/or humidities in occupied spaces. The hardware and software used to operate the facility are documented and the results of the first comprehensive experiments are presented. A microcomputer-based control/data acquisition system was employed to study the performance of two prototype radiator surfaces: 4-mil aluminized polyvinyl fluoride (PVF) and white painted surfaces set below polyethylene windscreens. The cooling rates for materials tested were determined and can be approximated by an equation (given). A computer model developed to simulate the cooling process is presented. (MCW)

  9. Mathematical Modeling – The Impact of Cooling Water Temperature Upsurge on Combined Cycle Power Plant Performance and Operation

    Science.gov (United States)

    Indra Siswantara, Ahmad; Pujowidodo, Hariyotejo; Darius, Asyari; Ramdlan Gunadi, Gun Gun

    2018-03-01

    This paper presents the mathematical modeling analysis on cooling system in a combined cycle power plant. The objective of this study is to get the impact of cooling water upsurge on plant performance and operation, using Engineering Equation Solver (EES™) tools. Power plant installed with total power capacity of block#1 is 505.95 MWe and block#2 is 720.8 MWe, where sea water consumed as cooling media at two unit condensers. Basic principle of analysis is heat balance calculation from steam turbine and condenser, concern to vacuum condition and heat rate values. Based on the result shown graphically, there were impact the upsurge of cooling water to increase plant heat rate and vacuum pressure in condenser so ensued decreasing plant efficiency and causing possibility steam turbine trip as back pressure raised from condenser.

  10. Optimizing cooling tower performance refrigeration systems, chemical plants, and power plants all have a resource quietly awaiting exploitation - cold water

    International Nuclear Information System (INIS)

    Burger, R.

    1993-01-01

    The cooling towers are hidden bonanzas for energy conservation and dollar savings when properly engineered and maintained. In many cases, the limiting factor of production is the quality and quantity of cold water coming off the cooling tower. The savings accrued in energy conservation and additional product manufactured can be an important factor on the operator's company's profit and loss sheet (7). Energy management analysis is a very important consideration in today's escalating climate of costs of energy. It is advisable to consider a thorough engineering inspection and evaluation of the entire plant to leave no stone unturned iii the search to reduce energy consumption (8). The cooling tower plays the major role on waste heat removal and should be given a thorough engineering inspection and evaluation by a specialist in this field. This can be performed at nominal cost and a formal report submitted with recommendations, budget costs, and evaluation of the thermal, structural, and mechanical condition of the equipment. This feasibility study will assist in determining the extent of efficiency improvement available with costs and projected savings. It can be stated that practically all cooling towers can be upgraded to perform at higher levels of efficiency which can provide a rapid, cost-effective payback. However, while all cooling tower systems might not provide such a dramatic cost payback as these case histories, the return of a customer's investment in upgrading his cooling tower can be a surprising factor of operation and should not be neglected

  11. Performance assessment of adding Cu-ultrafine particles into falling film desiccant

    International Nuclear Information System (INIS)

    Al-Mulla Ali, A.

    2006-01-01

    The concept of dehumidification between air and liquid desiccant for the improvement of the efficiency of heating and cooling fluids in industrial applications was discussed. The use of solid/liquid desiccants has received much attention in recent years because liquid desiccants can take moisture from surrounding air at low temperature and then release the moisture at high temperature to provide a continuous process of dehumidification of air and regeneration of liquid desiccant. This process can be used with conventional vapor compression cycles. This paper presented a comparative numerical study between parallel and counter flow configurations that examined the effects of various parameters on heat and mass transfer for the dehumidification and cooling processes of air and regeneration rate of liquid desiccant. Ultrafine particles were added to the falling film desiccant to investigate heat and mass transfer enhancement for both parallel and counter flow channels. The Cu-volume fraction in the falling film desiccant and dispersion effect were the important parameters. A mathematical model was therefore developed to account for the addition of Cu-ultrafine particles into the film desiccant. The dehumidification and cooling rate processes were found to improve with an increase in the Cu-ultrafine particles and dispersion effect. The new hybrid AC system was shown to improve indoor air quality, reduce energy consumption, and be environmentally safe. It was concluded that although the volume fraction and dispersion factor improve the dehumidification and cooling processes of the air, the improvements are not significant due to the small thickness of the falling-film desiccant. The regeneration process did not improve for either controlling parameter because of the small thickness of the film desiccant. 14 refs., 10 figs

  12. Performance comparison between ethanol phase-change immersion and active water cooling for solar cells in high concentrating photovoltaic system

    International Nuclear Information System (INIS)

    Wang, Yiping; Wen, Chen; Huang, Qunwu; Kang, Xue; Chen, Miao; Wang, Huilin

    2017-01-01

    Highlights: • Thermal performances of ethanol phase-change immersion and active water cooling are compared. • Effects of operation parameters on ethanol phase-change immersion are studied. • Optimum filling ratio is 30% for ethanol phase-change immersion cooling system. • Exergy efficiency of ethanol phase-change immersion method increases by 57%. - Abstract: This paper presents an optimized ethanol phase-change immersion cooling method to obtain lower temperature of dense-array solar cells in high concentrating photovoltaic system. The thermal performances of this system were compared with a conventional active water cooling system with minichannels from the perspectives of start-up characteristic, temperature uniformity, thermal resistance and heat transfer coefficient. This paper also explored the influences of liquid filling ratio, absolute pressure and water flow rate on thermal performances. Dense-array LEDs were used to simulate heat power of solar cells worked under high concentration ratios. It can be observed that the optimal filling ratio was 30% in which the thermal resistance was 0.479 °C/W and the heat transfer coefficient was 9726.21 W/(m 2 ·°C). To quantify the quality of energy output of two cooling systems, exergy analysis are conducted and maximum exergy efficiencies were 17.70% and 11.27%, respectively. The experimental results represent an improvement towards thermal performances of ethanol phase-change immersion cooling system due to the reduction in contact thermal resistance. This study improves the operation control and applications for ethanol phase-change immersion cooling technology.

  13. An experimental study on the design, performance and suitability of evaporative cooling system using different indigenous materials

    Science.gov (United States)

    Alam, Md. Ferdous; Sazidy, Ahmad Sharif; Kabir, Asif; Mridha, Gowtam; Litu, Nazmul Alam; Rahman, Md. Ashiqur

    2017-06-01

    relationship with air Velocity. Water consumption or evaporation rate increases with the increase in air velocity. Finally, the present study indicated that the coconut coir pads perform better than the other evaporative cooling pads and have higher potential as wetted-pad material. The outcomes of this study can provide an effective and low-cost solution in the form of evaporative cooling system, especially in an agricultural country like Bangladesh.

  14. Effect of façade systems on the performance of cooling ceilings: In situ measurements

    Directory of Open Access Journals (Sweden)

    Katharina Eder

    2015-03-01

    Full Text Available This article presents an innovative façade system designed to increase the thermal comfort inside an office room and to enhance the cooling capacity of the suspended cooling ceiling. A series of measurements is conducted in an existing office building with different façade systems (i.e., a combination of glazing and shading. An innovative façade system is developed based on this intensive set of measurements. The new system enhances the thermal comfort and cooling capacity of the suspended cooling ceiling. The main usage of the new system is the refurbishment and improvement of existing façade systems.

  15. Irradiation performance of U-Pu-Zr metal fuels for liquid-metal-cooled reactors

    International Nuclear Information System (INIS)

    Tsai, H.; Cohen, A.B.; Billone, M.C.; Neimark, L.A.

    1994-10-01

    This report discusses a fuel system utilizing metallic U-Pu-Zr alloys which has been developed for advanced liquid metal-cooled reactors (LMRs). Result's from extensive irradiation testing conducted in EBR-II show a design having the following key features can achieve both high reliability and high burnup capability: a cast nominally U-20wt %Pu-10wt %Zr slug with the diameter sized to yield a fuel smear density of ∼75% theoretical density, low-swelling tempered martensitic stainless steel cladding, sodium bond filling the initial fuel/cladding gap, and an as-built plenum/fuel volume ratio of ∼1.5. The robust performance capability of this design stems primarily from the negligible loading on the cladding from either fuel/cladding mechanical interaction or fission-gas pressure during the irradiation. The effects of these individual design parameters, e.g., fuel smear density, zirconium content in fuel, plenum volume, and cladding types, on fuel element performance were investigated in a systematic irradiation experiment in EBR-II. The results show that, at the discharge burnup of ∼11 at. %, variations on zirconium content or plenum volume in the ranges tested have no substantial effects on performance. Fuel smear density, on the other hand, has pronounced but countervailing effects: increased density results in greater cladding strain, but lesser cladding wastage from fuel/cladding chemical interaction

  16. Experiment Investigation on Electrical and Thermal Performances of a Semitransparent Photovoltaic/Thermal System with Water Cooling

    Directory of Open Access Journals (Sweden)

    Guiqiang Li

    2014-01-01

    Full Text Available Different from the semitransparent building integrated photovoltaic/thermal (BIPV/T system with air cooling, the semitransparent BIPV/T system with water cooling is rare, especially based on the silicon solar cells. In this paper, a semitransparent photovoltaic/thermal system (SPV/T with water cooling was set up, which not only would provide the electrical power and hot water, but also could attain the natural illumination for the building. The PV efficiency, thermal efficiency, and exergy analysis were all adopted to illustrate the performance of SPV/T system. The results showed that the PV efficiency and the thermal efficiency were about 11.5% and 39.5%, respectively, on the typical sunny day. Furthermore, the PV and thermal efficiencies fit curves were made to demonstrate the SPV/T performance more comprehensively. The performance analysis indicated that the SPV/T system has a good application prospect for building.

  17. Comparison of lead and sodium-cooled reactors - Safety, fuel cycle performance and some economical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Johan; Tucek, Kamil; Wider, Hartmut [Joint Research Centre, EC-JRC, Westerduinweg 3, P.O. Box 2, NL-0 1755 ZG Petten (Netherlands)

    2006-07-01

    This paper compares the Lead-cooled Fast Reactor (LFR) and the Sodium-cooled Fast Reactor (SFR) regarding different aspects of the coolant, safety and economics. A brief review of design and safety experience of an SFR (BN-600) and some safety philosophy of the most developed LFR (BREST) are presented as well. The pros and cons of the lead and the sodium coolants are discussed. This paper presents results concerning the coolant temperature evolution during three accident scenarios, i.e. Loss-Of- Flow (LOF), Loss-Of-Heat-Sink (LOHS), and Total-Loss-Of-Power (TLOP). It also studies possible moderators, like BeO and hydrides, for the core designs to have negative reactivity feedbacks and favorable reactivity swings. LFR seems to be able to accommodate more minor actinides than SFR at comparable coolant and Doppler feedbacks. We show that LFR can be designed both to breed and burn transuranics from LWRs. The hydrides lead to the most favorable reactivity feedbacks, but the poorest reactivity swing. It is shown that the LFR can handle the LOF transient better than the SFR. This is due to the much lower pressure drop in the LFR core. The coolant outlet temperatures stabilize at 2050 K and 940 K for SFR and LFR, respectively when no feedbacks are considered. Investigations also concern the SFR's performance when the pitch-to-diameter was increased from 1.2 to 1.4. For the LOHS and TLOP accidents their temperature evolutions are milder for the LFR since lead has a 50% larger volumetric heat capacity. For the TLOP the core outlet temperature of the LFR peaks at 1080 K after 2 days. Regarding economics it appears easier to avoid an intermediate cycle in an LFR than an SFR. (authors)

  18. Comparison of lead and sodium-cooled reactors - Safety, fuel cycle performance and some economical aspects

    International Nuclear Information System (INIS)

    Carlsson, Johan; Tucek, Kamil; Wider, Hartmut

    2006-01-01

    This paper compares the Lead-cooled Fast Reactor (LFR) and the Sodium-cooled Fast Reactor (SFR) regarding different aspects of the coolant, safety and economics. A brief review of design and safety experience of an SFR (BN-600) and some safety philosophy of the most developed LFR (BREST) are presented as well. The pros and cons of the lead and the sodium coolants are discussed. This paper presents results concerning the coolant temperature evolution during three accident scenarios, i.e. Loss-Of- Flow (LOF), Loss-Of-Heat-Sink (LOHS), and Total-Loss-Of-Power (TLOP). It also studies possible moderators, like BeO and hydrides, for the core designs to have negative reactivity feedbacks and favorable reactivity swings. LFR seems to be able to accommodate more minor actinides than SFR at comparable coolant and Doppler feedbacks. We show that LFR can be designed both to breed and burn transuranics from LWRs. The hydrides lead to the most favorable reactivity feedbacks, but the poorest reactivity swing. It is shown that the LFR can handle the LOF transient better than the SFR. This is due to the much lower pressure drop in the LFR core. The coolant outlet temperatures stabilize at 2050 K and 940 K for SFR and LFR, respectively when no feedbacks are considered. Investigations also concern the SFR's performance when the pitch-to-diameter was increased from 1.2 to 1.4. For the LOHS and TLOP accidents their temperature evolutions are milder for the LFR since lead has a 50% larger volumetric heat capacity. For the TLOP the core outlet temperature of the LFR peaks at 1080 K after 2 days. Regarding economics it appears easier to avoid an intermediate cycle in an LFR than an SFR. (authors)

  19. Electrical and optical performance of transparent conducting oxide films deposited by electrostatic spray assisted vapour deposition.

    Science.gov (United States)

    Hou, Xianghui; Choy, Kwang-Leong; Liu, Jun-Peng

    2011-09-01

    Transparent conducting oxide (TCO) films have the remarkable combination of high electrical conductivity and optical transparency. There is always a strong motivation to produce TCO films with good performance at low cost. Electrostatic Spray Assisted Vapor Deposition (ESAVD), as a variant of chemical vapour deposition (CVD), is a non-vacuum and low-cost deposition method. Several types of TCO films have been deposited using ESAVD process, including indium tin oxide (ITO), antimony-doped tin oxide (ATO), and fluorine doped tin oxide (FTO). This paper reports the electrical and optical properties of TCO films produced by ESAVD methods, as well as the effects of post treatment by plasma hydrogenation on these TCO films. The possible mechanisms involved during plasma hydrogenation of TCO films are also discussed. Reduction and etching effect during plasma hydrogenation are the most important factors which determine the optical and electrical performance of TCO films.

  20. Simulation and performance enhancement of the air cooling system in a DC/AC power converter station

    Energy Technology Data Exchange (ETDEWEB)

    Lozowy, R.; El-Shaboury, A.; Soliman, H.; Ormiston, S. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Mechanical and Manufacturing Engineering

    2010-07-01

    This study analyzed the flow structure and heat transfer in a large 3-dimensional domain with turbulence, mixed convection, an impinging jet, and flow over heated blocks. The objective was to better understand turbulent mixed-convection cooling of heat-generating bodies in 3-dimensional enclosures, which is important to industry. The cooling of 2 thyristor valve halls was simulated. Each valve hall housed 3 towers that contained electronics used in DC/AC power conversion. The simulation results included the magnitudes of the net air flows for all the inter-block gaps and the maximum temperature in each gap. A parametric study was also performed to investigate the effects of the air inlet location, size and aspect ratio. The effects of the air injection angle on cooling effectiveness was also examined. The study showed that for fixed inlet mass flow rate, significant improvement in the cooling effectiveness can be obtained by changing the injection angle of the inlet air jet, the location of the inlet grill, or the size of the inlet grill. It was concluded that these study results may be relevant to other applications, such as the design of power transformers, the design of cooling systems for spent nuclear fuel and computer server cooling racks. 13 refs., 12 figs.

  1. The effects of regeneration temperature of the desiccant wheel on the performance of desiccant cooling cycles for greenhouse thermally insulated

    Science.gov (United States)

    Rjibi, Amel; Kooli, Sami; Guizani, Amenaallah

    2018-05-01

    The use of solar energy for cooling greenhouses in the hot period in Mediterranean climate is an important issue. Desiccant evaporative cooling (DEC) system is advantageous because it uses a low grade thermal energy and preserves the merits to be friendly environmentally technology. In this paper, a numerical investigation was carried out on a desiccant cooling system powered by air solar collectors coupled to an insulated greenhouse. The influence of the regeneration temperature on the air stream properties at every system component state point was studied. The performance of the desiccant cooling system was evaluated in terms of thermal and electric coefficient of performance. Results show that the best performance of the system (COPel = 14 and COPth = 0.94) was obtained for a 60 °C regeneration temperature and a supply flow rate ratio of 0.2. An economic analysis shows that the use of the DEC system for greenhouse cooling is attractive and profitable since the payback period is 1 years. The use of the proposed system allows saving 9396 kWh/year of electric energy compared to conventional system.

  2. Experimental performance evaluation for a carbon dioxide light commercial cooling application under transcritical and subcritical conditions

    International Nuclear Information System (INIS)

    Boccardi, G.; Calabrese, N.; Celata, G.P.; Mastrullo, R.; Mauro, A.W.; Perrone, A.; Trinchieri, R.

    2013-01-01

    CO 2 is one of the most interesting non toxic, nor flammable, low GWP natural fluid to be used in applications with a large direct contribution to global warming, such as vending machines. In this paper the results of an experimental investigation on a small capacity, air-forced refrigerating plant working with CO 2 are presented. The air inlet temperatures at gas cooler and evaporator were varied between 16 °C and 31 °C and between −25 °C and 25 °C, respectively, to cover the range of temperatures under conditions typical of commercial refrigeration, during quasi-steady operation. The thermodynamic analysis of the system performance was carried on varying independently the pressure at the gas cooler, by overfeeding the liquid receiver to point out the effect of refrigerant charge. The results allow to describe the performance of the system in a map varying the boundary conditions; at the same time the corresponding variations of the thermodynamic cycle, the COP and the mass flow rate are reported. -- Highlights: ► A light commercial refrigerating plant working with CO 2 was tested in order to evaluate its performance. ► 71 experimental points were collected varying the flow rates, the temperatures of air sources and the refrigerant charge. ► Mass flow rate, cooling capacity, electrical power and COP were evaluated as a function of pressures and superheating. ► The segregate influence of each operating parameter on each performance indicator was calculated. ► A map of plant performance as a function of air source temperatures is reported

  3. The impact of cooling ponds in North Central Texas on dairy farm performance

    NARCIS (Netherlands)

    Tomaszewski, M.A.; Haan, de M.H.A.; Thompson, J.A.; Jordan, E.R.

    2005-01-01

    The objective of this study was to determine whether measurable differences existed between farms with and without cooling ponds. Data from Dairy Herd Improvement records for 1999 through 2002 were obtained on 42 herds located in North Central Texas. Nineteen herds had installed cooling ponds,

  4. Secondary flows in the cooling channels of the high-performance light-water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Laurien, E.; Wintterle, Th. [Stuttgart Univ., Institute for Nuclear Technolgy and Energy Systems (IKE) (Germany)

    2007-07-01

    The new design of a High-Performance Light-Water Reactor (HPLWR) involves a three-pass core with an evaporator region, where the compressed water is heated above the pseudo-critical temperature, and two superheater regions. Due to the strong dependency of the supercritical water density on the temperature significant mass transfer between neighboring cooling channels is expected if the temperature is unevenly distributed across the fuel element. An inter-channel flow is then superimposed to the secondary flow vortices induced by the non-isotropy of turbulence. In order to gain insight into the resulting flow patterns as well as into temperature and density distributions within the various subchannels of the fuel element CFD (Computational Fluid Dynamics) calculations for the 1/8 fuel element are performed. For simplicity adiabatic boundary conditions at the moderator box and the fuel element box are assumed. Our investigation confirms earlier results obtained by subchannel analysis that the axial mass flux is significantly reduced in the corner subchannel of this fuel element resulting in a net mass flux towards the neighboring subchannels. Our results provide a first estimation of the magnitude of the secondary flows in the pseudo-critical region of a supercritical light-water reactor. Furthermore, it is demonstrated that CFD is an efficient tool for investigations of flow patterns within nuclear reactor fuel elements. (authors)

  5. Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Geer, S. B. van der [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2014-12-28

    Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

  6. Effect of Target Configuration on the Neutronic Performance of the Gas-Cooled ADS

    CERN Document Server

    Biss, K; Shetty, N; Nabbi, R

    2013-01-01

    With the utilization of nuclear energy transuranic elements like Pu, Am and Cm are produced causing high, long term radioactivity and radio toxicity, respectively. To reduce the radiological impact on the environment and to the repository Partitioning and Transmutation is considered as an efficient way. In this respect comprehensive research works are performed at different research institutes worldwide. The results show that the transmutation of TRU is achieved with fast neutrons due to the higher fission probability. Based on Accelerator Driven Systems (ADS) those neutrons are used in a particular system, in which mainly liquid metal eutectic (lead bismuth) is used as coolant. The neutronic performance of an ADS system based on gas cooling was studied in this work by using the simulation tool MCNPX. The usage of the Monte-Carlo method in MCNPX allows the simulation of the physical processes in a 3D-model of the core. In dependence of the spallation target material and design several parameters like the mult...

  7. Barrier Performance of CVD Graphene Films Using a Facile P3HT Thin Film Optical Transmission Test

    Directory of Open Access Journals (Sweden)

    Srinivasa Kartik Nemani

    2018-01-01

    Full Text Available The barrier performance of CVD graphene films was determined using a poly(3-hexylthiophene (P3HT thin film optical transmission test. P3HT is a semiconducting polymer that photo-oxidatively degrades upon exposure to oxygen and light. The polymer is stable under ambient conditions and indoor lighting, enabling P3HT films to be deposited and encapsulated in air. P3HT’s stability under ambient conditions makes it desirable for an initial evaluation of barrier materials as a complimentary screening method in combination with conventional barrier tests. The P3HT test was used to demonstrate improved barrier performance for polymer substrates after addition of CVD graphene films. A layer-by-layer transfer method was utilized to enhance the barrier performance of monolayer graphene. Another set of absorption measurements were conducted to demonstrate the barrier performance of graphene and the degradation mechanism of graphene/P3HT over multiple wavelengths from 400 to 800 nm. The absorption spectra for graphene/polymer composite were simulated by solving Fresnel equations. The simulation results were found to be in good agreement with the measured absorption spectra. The P3HT degradation results qualitatively indicate the potential of graphene films as a possible candidate for medium performance barriers.

  8. Fabrication and Performance Study of Uniform Thin Film Integrated ...

    African Journals Online (AJOL)

    The transmission line model of a uniform rectangular thin film R-C-KR structure consisting of a dielectric layer of constant per unit shunt capacitance C sandwiched between two resistive thin films of constant per unit length resistances R and KR has been analysed using the concept of matrix parameter functions. The above ...

  9. Theoretical investigations on improving performance of cooling systems for fuel cell vehicles; Theoretische Untersuchungen zur Kuehlleistungssteigerung durch innovative Kuehlsysteme fuer Brennstoffzellen-Elektrofahrzeuge

    Energy Technology Data Exchange (ETDEWEB)

    Reichler, Mark

    2008-04-01

    In this work theoretical investigations are carried out for cooling systems, which are used in fuel cell vehicles. This work focuses mainly on the capability of increasing the heat rejection rate by using new alternative cooling systems and by improving the conventional cooling system. Fuel cell vehicles have a higher demand of heat rejection to the ambient than comparable vehicles with combustion engine. The performance of conventional liquid cooling systems, especially at high loads and high ambient temperatures, is often not sufficient anymore. Hence, cooling systems with improved performance are necessary for fuel cell vehicles. The investigations in this work are based on DaimlerChrysler's ''A-Class'' having a PEM-Fuel Cell system integrated. Specific computational models are developed for radiators and condensers to evaluate the performance of different cooling concepts. The models are validated with experimental data. Based on an intensive investigation in the open literature the state of the art of cooling systems for fuel cell vehicles is depicted. Furthermore new cooling concepts as an alternative to the liquid cooling system are presented. The method of cooling the fuel cell by using two-phase transition shows the greatest capability to increase the cooling performance. Hence, this concept is investigated in detail. Two different concepts with three different refrigerants (R113, R245fa und R236fa) are analyzed. Cooling performance of this concept shows improvement of 18.2 up to 32.6 % compared to the conventional liquid cooling system. Thus, a two phase cooling system represents an alternative cooling system for fuel cell vehicles, which should be closer investigated by experiments. (orig.)

  10. Tribological performance of ultrathin diamond-like carbon films prepared by plasma-based ion implantation

    International Nuclear Information System (INIS)

    Liao, J X; Li, E Q; Tian, Z; Pan, X F; Xu, J; Jin, L; Yang, H G

    2008-01-01

    Ultrathin diamond-like carbon (DLC) films with thicknesses of 5-60 nm have been prepared on Si by plasma-based ion implantation. Raman spectrum and x-ray photoelectron spectroscopy (XPS) show that these DLC films present high sp 3 /sp 2 ratios. XPS also displays that each DLC film firmly adheres to the Si substrate owing to a C-Si transition layer. Atomic force microscopy shows that the DLC films are smooth and compact with average roughness (R a ) of about 0.25 nm. Sliding friction experiments reveal that these DLC films show significantly improved tribological performance. With increase of DLC film thickness, the sp 3 /sp 2 ratio increases, the roughness decreases, the hardness increases, the adhesive wear lightens and thereby the tribological performance becomes enhanced. Also, the effects of the applied load and the reciprocating frequency on the tribological performance are discussed

  11. Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

    Science.gov (United States)

    Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

    2016-06-01

    In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

  12. A quantitative evaluation of the production performance of ice slurry by the oscillatory moving cooled wall method

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Masahiko; Fukusako, Shoichiro [Hokkaido Univ., Sapporo (Japan). Graduate School of Engineering; Kawabe, Hiromichi [Senshu Univ., Bibai (Japan). Hokkaido College. Dept. of Agricultural Engineering

    2002-03-01

    Ice slurry has recently been utilized for a variety of engineering fields such as thermal energy storage and high-density energy transportation. In this paper, as a production method of ice slurry, the oscillatory rotating cooled tube method was proposed. A vertical cooled tube was installed in a test vessel that was filled with ethylene glycol solution being forced to move within an aqueous binary solution to produce the ice slurry. Production performance of ice slurry by the present method was determined under a variety of conditions, such as initial concentration of solution, angular acceleration and rotation angle for the oscillation motion of the cooled tube. The production performance was evaluated analytically by constructing a numerical model. The analysis was made to determine the separation condition of ice layer from the cooled tube surface at first, then the production rate of ice slurry was assessed. It was found from the present study that the ice slurry was produced continuously under the appropriate operating conditions in which the separation of ice layer was caused by oscillating motion of the cooled tube. (Author)

  13. Whole-body pre-cooling and heat storage during self-paced cycling performance in warm humid conditions.

    Science.gov (United States)

    Kay, D; Taaffe, D R; Marino, F E

    1999-12-01

    The aim of this study was to establish the effect that pre-cooling the skin without a concomitant reduction in core temperature has on subsequent self-paced cycling performance under warm humid (31 degrees C and 60% relative humidity) conditions. Seven moderately trained males performed a 30 min self-paced cycling trial on two separate occasions. The conditions were counterbalanced as control or whole-body pre-cooling by water immersion so that resting skin temperature was reduced by approximately 5-6 degrees C. After pre-cooling, mean skin temperature was lower throughout exercise and rectal temperature was lower (P body sweat fell from 1.7+/-0.1 l x h(-1) to 1.2+/-0.1 l h(-1) (P < 0.05). The distance cycled increased from 14.9+/-0.8 to 15.8+/-0.7 km (P < 0.05) after pre-cooling. The results indicate that skin pre-cooling in the absence of a reduced rectal temperature is effective in reducing thermal strain and increasing the distance cycled in 30 min under warm humid conditions.

  14. Chemical Annealing of Zinc Tetraphenylporphyrin Films: Effects on Film Morphology and Organic Photovoltaic Performance

    KAUST Repository

    Trinh, Cong

    2012-07-10

    We present a chemical annealing process for organic thin films. In this process, a thin film of a molecular material, such as zinc tetraphenylporphyrin (ZnTPP), is exposed to a vapor of nitrogen-based ligand (e.g., pyrazine, pz, and triazine, tz), forming a film composed of the metal-ligand complex. Fast and quantitative formation of the complex leads to marked changes in the morphology and optical properties of the film. X-ray diffraction studies show that the chemical annealing process converts amorphous ZnTPP films to crystalline ZnTPP•ligand films, whose porphryin planes lie nearly parallel to the substrate (average deviation is 8° for the ZnTPP•pz film). Organic solar cells were prepared with ZnTPP donor and C 60 acceptor layers. Devices were prepared with and without chemical annealing of the ZnTPP layer with a pyrazine ligand. The devices with chemically annealed ZnTPP donor layer show an increase in short-circuit current (J SC) and fill factor (FF) relative to analogous unannealed devices, presumably because of enhanced exciton diffusion length and improved charge conductivity. The open circuit voltages (V OC) of the chemically annealed devices are lower than their unannealed counterpart because of enhanced polaron pair recombination at the donor/acceptor heterojunction. A net improvement of 5-20% in efficiency has been achieved, after chemical annealing of ZnTPP films with pyrazine. © 2012 American Chemical Society.

  15. Chemical Annealing of Zinc Tetraphenylporphyrin Films: Effects on Film Morphology and Organic Photovoltaic Performance

    KAUST Repository

    Trinh, Cong; Whited, Matthew T.; Steiner, Andrew; Tassone, Christopher J.; Toney, Michael F.; Thompson, Mark E.

    2012-01-01

    We present a chemical annealing process for organic thin films. In this process, a thin film of a molecular material, such as zinc tetraphenylporphyrin (ZnTPP), is exposed to a vapor of nitrogen-based ligand (e.g., pyrazine, pz, and triazine, tz

  16. Systematic investigation of the effects of organic film structure on light emitting diode performance

    Science.gov (United States)

    Joswick, M. D.; Campbell, I. H.; Barashkov, N. N.; Ferraris, J. P.

    1996-09-01

    We present a systematic investigation of the effects of organic film structure on light emitting diode (LED) performance. Metal/organic film/metal LEDs were fabricated using a five ring, poly(phenylene vinylene) related oligomer as the active layer. The structure of the vacuum evaporated oligomer films was varied from amorphous to polycrystalline by changing the substrate temperature during deposition. The intrinsic properties of the oligomer films and the LED performance were measured. The measured intrinsic film properties include: optical absorption, photoluminescence (PL) spectra, PL lifetime, PL efficiency, and effective carrier mobility. The measured device characteristics include current-voltage, capacitance-voltage, electroluminescence (EL) efficiency, and the contact metal/organic film Schottky barrier heights. The optical absorption and PL properties of the films are weakly dependent on film structure but the effective carrier mobility decreases with increasing crystallinity. The EL quantum efficiency decreases by more than one order of magnitude, the drive voltage at a fixed current increases, and the electron Schottky barrier height increases as the crystallinity of the film is increased. The diode current-voltage characteristic is determined by the dominant hole current and the electroluminescence efficiency is controlled by the contact limited electron injection. These results demonstrate significant effects of organic film structure on the performance of organic LEDs.

  17. Systematic investigation of the effects of organic film structure on light emitting diode performance

    Energy Technology Data Exchange (ETDEWEB)

    Joswick, M.D.; Campbell, I.H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Barashkov, N.N.; Ferraris, J.P. [The University of Texas at Dallas, Richardson, Texas 75080 (United States)

    1996-09-01

    We present a systematic investigation of the effects of organic film structure on light emitting diode (LED) performance. Metal/organic film/metal LEDs were fabricated using a five ring, poly(phenylene vinylene) related oligomer as the active layer. The structure of the vacuum evaporated oligomer films was varied from amorphous to polycrystalline by changing the substrate temperature during deposition. The intrinsic properties of the oligomer films and the LED performance were measured. The measured intrinsic film properties include: optical absorption, photoluminescence (PL) spectra, PL lifetime, PL efficiency, and effective carrier mobility. The measured device characteristics include current{endash}voltage, capacitance{endash}voltage, electroluminescence (EL) efficiency, and the contact metal/organic film Schottky barrier heights. The optical absorption and PL properties of the films are weakly dependent on film structure but the effective carrier mobility decreases with increasing crystallinity. The EL quantum efficiency decreases by more than one order of magnitude, the drive voltage at a fixed current increases, and the electron Schottky barrier height increases as the crystallinity of the film is increased. The diode current{endash}voltage characteristic is determined by the dominant hole current and the electroluminescence efficiency is controlled by the contact limited electron injection. These results demonstrate significant effects of organic film structure on the performance of organic LEDs. {copyright} {ital 1996 American Institute of Physics.}

  18. Gas Sensing Performance of Pure and Modified BST Thick Film Resistor

    Directory of Open Access Journals (Sweden)

    G. H. JAIN

    2008-04-01

    Full Text Available Barium Strontium Titanate (BST-(Ba0.87Sr0.13TiO3 ceramic powder was prepared by mechanochemical process. The thick films of different thicknesses of BST were prepared by screen-printing technique and gas-sensing performance of these films was tested for various gases. The films showed highest response and selectivity to ammonia gas. The pure BST film was surface modified by surfactant CrO3 by using dipping technique. The surface modified film suppresses the response to ammonia and enhances to H2S gas. The surface modification of films changes the adsorption-desorption relationship with the target gas and shifts its selectivity. The gas response, selectivity, response and recovery time of the pure and modified films were measured and presented.

  19. Cross-winds effect on the performance of natural draft wet cooling towers

    Energy Technology Data Exchange (ETDEWEB)

    Al-Waked, R. [Dhofar Univ., Mechanical Engineering Dept., College of Engineering, Sultanate of Oman (Oman)

    2010-01-15

    Effects of cross-winds on the thermal performance of natural draft wet cooling towers (NDWCTs) have been investigated. A three-dimensional CFD model has been used to determine the effect of cross-winds on NDWCTs performance surrounded by power plant building structures. The three-dimensional CFD model has utilized the standard k-{epsilon} turbulence model as the turbulence closure. Two cases have been investigated: a stand-alone NDWCT and two NDWCTs within a proposed power plant structures (PPS). It has been found that regardless of the cross-winds direction, an increase of 1.3 k or more could be predicted at cross-winds speeds greater than 4 m/s. Furthermore, the performance of NDWCTs under cross-winds has been found to be dependent on the three major factors: the structure of the approaching cross-winds and whether it is disturbed or undisturbed, the location of the NDWCT in the wake of the other NDWCT, and the location of the NDWCT in front of/in the wake of the PPS. When comparing results from the stand-alone and from the NDWCTs within PPS simulations, differences in {delta}T{sub wo} were found to be less than 1 K for the whole span of cross-winds speeds and could be decreased to 0.7 K for speeds less than 8 m/s. Finally, results obtained from the simulation of a stand-alone NDWCT could be used instead of those from NDWCTs within PPS at a certain cross-winds direction for qualitative comparisons. (authors)

  20. Cross-winds effect on the performance of natural draft wet cooling towers

    International Nuclear Information System (INIS)

    Al-Waked, R.

    2010-01-01

    Effects of cross-winds on the thermal performance of natural draft wet cooling towers (NDWCTs) have been investigated. A three-dimensional CFD model has been used to determine the effect of cross-winds on NDWCTs performance surrounded by power plant building structures. The three-dimensional CFD model has utilized the standard k-ε turbulence model as the turbulence closure. Two cases have been investigated: a stand-alone NDWCT and two NDWCTs within a proposed power plant structures (PPS). It has been found that regardless of the cross-winds direction, an increase of 1.3 k or more could be predicted at cross-winds speeds greater than 4 m/s. Furthermore, the performance of NDWCTs under cross-winds has been found to be dependent on the three major factors: the structure of the approaching cross-winds and whether it is disturbed or undisturbed, the location of the NDWCT in the wake of the other NDWCT, and the location of the NDWCT in front of/in the wake of the PPS. When comparing results from the stand-alone and from the NDWCTs within PPS simulations, differences in ΔT wo were found to be less than 1 K for the whole span of cross-winds speeds and could be decreased to 0.7 K for speeds less than 8 m/s. Finally, results obtained from the simulation of a stand-alone NDWCT could be used instead of those from NDWCTs within PPS at a certain cross-winds direction for qualitative comparisons. (authors)

  1. Performance Optimization of the Water Cooling System for Resonance Frequency Control of the PEFP DTL

    International Nuclear Information System (INIS)

    Kim, K. Y.; Kim, H. K.; Kim, H. S.; Yoon, J. C.; Sohn, Y. K.; Kweon, S. J.; Park, J.; Kim, K. S.

    2010-03-01

    The objective of in this research project is prototype cooling water skid of separated closed loop in order to supply and withdraw low conductivity deionized water in drift tube of drift tube linac as core components of proton accelerates. This report is dealt with design specification of J-PARC 400 MeV Linac cooling water system, PEFP DTL cooling system, specification of RCCS21-24, RCCS101 with pump, loss coefficient for DTL2 modeling, pressure drop with flow rate of heat exchanger.

  2. Performance of a conduction-cooled high-temperature superconducting bearing

    International Nuclear Information System (INIS)

    Strasik, M.; Hull, J.R.; Johnson, P.E.; Mittleider, J.; McCrary, K.E.; McIver, C.R.; Day, A.C.

    2008-01-01

    We report rotational loss measurements for a high-temperature superconducting (HTS) bearing whose cooling consists of a thermal conduction path to the cold head of a cryocooler. Losses have been measured for rotational rates up to 14,500 rpm at different HTS temperatures. The rotational losses decrease with decreasing HTS temperature. For temperatures that can be obtained in a liquid-nitrogen thermosiphon system, at a given speed and gap, the loss of the conduction-cooled HTS bearing is not significantly higher than the loss of a nearly identical HTS bearing cooled by flowing nitrogen from the thermosiphon

  3. Comparison of Oxidation Stability and Quenchant Cooling Curve Performance of Soybean Oil and Palm Oil

    Science.gov (United States)

    Said, Diego; Belinato, Gabriela; Sarmiento, Gustavo S.; Otero, Rosa L. Simencio; Totten, George E.; Gastón, Analía; Canale, Lauralice C. F.

    2013-07-01

    The potential use of vegetable oil-derived industrial oils continues to be of great interest because vegetable oils are relatively non-toxic, biodegradable, and they are a renewable basestock alternative to petroleum oil. However, the fatty ester components containing conjugated double bonds of the triglyceride structure of vegetable oils typically produce considerably poorer thermal-oxidative stability than that achievable with petroleum basestocks under typical use conditions. Typically, these conditions involve furnace loads of hot steel (850 °C), which are rapidly immersed and cooled to bath temperatures of approximately 50-60 °C. This is especially true when a vegetable oil is held in an open tank with agitation and exposed to air at elevated temperatures for extended periods of time (months or years). This paper will describe the thermal-oxidative stability and quenching performance of soybean oil and palm oil and the resulting impact on the heat transfer coefficient. These results are compared to typical fully formulated, commercially available accelerated (fast) and an unaccelerated (slow) petroleum oil-based quenchants.

  4. Experimental performance of indirect air–liquid membrane contactors for liquid desiccant cooling systems

    International Nuclear Information System (INIS)

    Das, Rajat Subhra; Jain, Sanjeev

    2013-01-01

    Owing to the stringent indoor air quality (IAQ) requirements and high cost of desiccants, one of the major concerns in liquid desiccant technology has been the carryover, which can be eliminated through indirect contact between desiccant and air. Membrane contactors using microporous semipermeable hydrophobic membranes have a great potential in this regard. This communication investigates the performance of semipermeable membrane based indirect contactors as dehumidifiers in liquid desiccant cooling applications. Experiments on different types of membrane contactors are carried out using lithium chloride (LiCl) solution as desiccant. The membrane contactors consist of alternate channels of air and liquid desiccant flowing in cross-flow direction. Hydrophobic membranes form a liquid tight, vapor permeable porous barrier between hygroscopic solution and moist air, thus eliminating carryover of desiccant droplets. In order to provide maximum contact area for air–desiccant interaction, a wicking material is sandwiched between two membranes in the liquid channel. It is observed that vapor flux upto 1300 g/m 2 h can be achieved in a membrane contactor with polypropylene (PP) membranes, although the dehumidification effectiveness remains low. The effect of key parameters on the transmembrane vapor transport is presented in the paper. - Highlights: • Indirect membrane contactors developed to avoid carryover in liquid desiccant system. • Dehumidification effectiveness and vapor flux reported under varying conditions. • Vapor flux upto 1295 g/m 2 h in polypropylene contactor with high area density. • Dehumidification effectiveness with LiCl solution varies within 23% to 45%

  5. Heat transfer performance of heat pipe for passive cooling of spent fuel pool

    International Nuclear Information System (INIS)

    Wang Minglu; Xiong Zhengqin; Gu Hanyang; Ye Cheng; Cheng Xu

    2014-01-01

    A large-scale loop heat pipe has no electricity driven component and high efficiency of heat transfer. It can be used for the passive cooling of the SFP after SBO to improve the safety performance of nuclear power plants. In this paper, such a large-scale loop heat pipe is studied experimentally. The heat transfer rate, evaporator average heat transfer coefficient operating temperature, operating pressure and ammonia flow rate have been obtained with the water flow ranging from 0.007 m/s to 0.02 m/s outside the evaporator section, heating water temperature in the range of 50 to 90℃, air velocity outside the condensation section ranging from 0.5 to 2.5 m/s. It is found that the heat transfer rate reaches as high as 20.1 kW. Parametric analysis indicates that, the heat transfer rate and ammonia flow rate are influenced significantly by hot water inlet temperature and velocity, while beyond 1.5 m/s, the effect of air velocity outside the condensation section is minor. (authors)

  6. Evaluation of post-LOCA long term cooling performance in Korean standard nuclear power plants

    International Nuclear Information System (INIS)

    Bang, Young Seok; Jung, Jae Won; Seul, Kwang Won; Kim, Hho Jung

    2001-01-01

    The post-LOCA long term cooling (LTC) performance of the Korean Standard Nuclear Power Plant (KSNPP) is analyzed for both small break loss-of-coolant accidents (LOCA) and large break LOCA at cold leg. The RELAP5/MOD3.2.2 beta code is used to calculate the LTC sequences based on the LTC plan of the Korean Standard Nuclear Power Plants (KSNPP). A standard input model is developed such that LOCA and the followed LTC sequence can be calculated in a single run for both small break LOCA and large break LOCA. A spectrum of small break LOCA ranging from 0.02 to 0.5 ft 2 of break area and a double-ended guillotine break are analyzed. Through the code calculations, the thermal-hydraulic behavior and the boron behavior are evaluated and the effect of the important action including the safety injection tank (SIT) isolation and the simultaneous injection in LTC procedure is investigated. As a result, it is found that the sufficient margin is available in avoiding the boron precipitation in the core. It is also found that a further specific condition for the SIT isolation action need to be setup and it is recommended that the early initiation of the simultaneous injection be taken for larger break LTC sequences. (author)

  7. Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring

    Directory of Open Access Journals (Sweden)

    Zheng Zuo

    2014-01-01

    Full Text Available Embedded cool-pipes are very important for massive concrete because their cooling effect can effectively avoid thermal cracks. In this study, a data mining approach to analyzing the thermal performance of cool-pipes via in situ monitoring is proposed. Delicate monitoring program is applied in a high arch dam project that provides a good and mass data source. The factors and relations related to the thermal performance of cool-pipes are obtained in a built theory thermal model. The supporting vector machine (SVM technology is applied to mine the data. The thermal performances of iron pipes and high-density polyethylene (HDPE pipes are compared. The data mining result shows that iron pipe has a better heat removal performance when flow rate is lower than 50 L/min. It has revealed that a turning flow rate exists for iron pipe which is 80 L/min. The prediction and classification results obtained from the data mining model agree well with the monitored data, which illustrates the validness of the approach.

  8. Thermal performance of mini-channel liquid cooled cylinder based battery thermal management for cylindrical lithium-ion power battery

    International Nuclear Information System (INIS)

    Zhao, Jiateng; Rao, Zhonghao; Li, Yimin

    2015-01-01

    Highlights: • A new kind of cooling method for cylindrical batteries based on mini-channel liquid cooled cylinder (LCC) is proposed. • The capacity of reducing the T max is limited through increasing the mass flow rate. • The capability of heat dissipation is enhanced first and then weaken along with the rising of entrance size. - Abstract: Battery thermal management is a very active research focus in recent years because of its great essentiality for electric vehicles. In order to maintain the maximum temperature and local temperature difference in appropriate range, a new kind of cooling method for cylindrical batteries which is based on mini-channel liquid cooled cylinder is proposed in this paper. The effects of channel quantity, mass flow rate, flow direction and entrance size on the heat dissipation performance were investigated numerically. The results showed that the maximum temperature can be controlled under 40 °C for 42,110 cylindrical batteries when the number of mini-channel is no less than four and the inlet mass flow rate is 1 × 10 −3 kg/s. Considering both the maximum temperature and local temperature difference, the cooling style by liquid cooled cylinder can demonstrate advantages compared to natural convection cooling only when the channel number is larger than eight. The capability of reducing the maximum temperature is limited through increasing the mass flow rate. The capacity of heat dissipation is enhanced first and then weakened along with the rising of entrance size, when the inlet mass flow rate is constant

  9. Evaluation of ejector performance for an organic Rankine cycle combined power and cooling system

    International Nuclear Information System (INIS)

    Zhang, Kun; Chen, Xue; Markides, Christos N.; Yang, Yong; Shen, Shengqiang

    2016-01-01

    Highlights: • The performance of an ejector in an Organic Rankine Cycle and ejector refrigeration cycle (EORC) was evaluated. • The achieved entrainment ratio and COP of an EORC system is affected significantly by the evaporator conditions (such as temperature, pressure and flow rate). • An optimum distance of 6 mm nozzle position was found that ensures a maximum entrainment ratio, the best efficiency and lowest loss in the ejector. • A reduced total pressure loss between the nozzle inlet and exit leads to a lower energy loss, a higher entrainment ratio and better overall ejector performance. - Abstract: Power-generation systems based on organic Rankine cycles (ORCs) are well suited and increasingly employed in the conversion of thermal energy from low temperature heat sources to power. These systems can be driven by waste heat, for example from various industrial processes, as well as solar or geothermal energy. A useful extension of such systems involves a combined ORC and ejector-refrigeration cycle (EORC) that is capable, at low cost and complexity, of producing useful power while having a simultaneous capacity for cooling that is highly desirable in many applications. A significant thermodynamic loss in such a combined energy system takes place in the ejector due to unavoidable losses caused by irreversible mixing in this component. This paper focuses on the flow and transport processes in an ejector, in order to understand and quantify the underlying reasons for these losses, as well as their sensitivity to important design parameters and operational variables. Specifically, the study considers, beyond variations to the geometric design of the ejector, also the role of changing the external conditions across this component and how these affect its performance; this is not only important in helping develop ejector designs in the first instance, but also in evaluating how the performance may shift (in fact, deteriorate) quantitatively when the device

  10. Theoretical study on volatile organic compound removal and energy performance of a novel heat pump assisted solid desiccant cooling system

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Fang, Lei; Zhang, Ge

    2015-01-01

    for cooling, dehumidification and indoor air cleaning in normal office, commercial or residential buildings. The desiccant rotor was used for dehumidification and indoor air cleaning; the heat pump provided sensible cooling and regeneration heat for the desiccant rotor. The theoretical model consisted of two...... and predicted. The theoretical model was validated by experimental data. Validating results showed that the model could be used to predict the performance of HP-SDC. The results also showed that the HP-SDC could clean air borne contaminants effectively and could provide an energy efficient choice...

  11. Cool-down performance of CICC superconducting coils for the CHMFL

    Science.gov (United States)

    Xie, Y.; Li, J.; Ouyang, Z. R.

    2017-10-01

    A hybrid magnet composed of a water-cooled magnet and a superconducting magnet was developed at the High Magnetic Field Laboratory of the Chinese Academy of Sciences. The superconducting coils made of Nb3Sn CICC were cooled by the forced flow of supercritical helium at 4.5 K. The paper presents the cryogenic system framework, and reports the characteristics of the supercritical helium in a cable-in-conduit conductor (CICC), including the friction factor change during the cooling process, the heat transfer coefficient from 4.6 K to 6.8 K, and the helium mass flow rate distribution. After the 23-day cooling process, the temperature reached 4.5 K. The operation process was introduced in the paper.

  12. Performance test of filtering system for controlling the turbidity of secondary cooling water in HANARO

    International Nuclear Information System (INIS)

    Park, Y. C.; Woo, J. S.; Jo, Y. K.; Loo, J. S.; Lim, N. Y.

    2001-01-01

    There is about 80 m 3 /h loss of the secondary cooling water by evaporation, windage and blowdown during the operation of HANARO, 30 MW research reactor. When the secondary cooling water is treated by high Ca-hardness treatment program for minimizing the blowdown loss, only the trubidity exceeds the limit. By adding filtering system it was confirned, through the relation of turbidity and filtering rate of secondary cooling water, that the turbidity is reduced below the limit (5 deg.) by 2 % of filtering rate without blowdown. And it was verified, through the field performace test of filtering system under normal operation condition, that the circulation pumps get proper capacity and that filter units reduce the turbidity below the limit. Therefore, the secondary cooling water can be treated by the high Ca-hardness program and filter system without blowdown

  13. Warm Up and Cool Down: Reduce Risk of Injury and Improve Athletic Performance

    Science.gov (United States)

    ... exercise, but more research is needed. Although there's controversy about whether warming up and cooling down can ... your agreement to the Terms and Conditions and Privacy Policy linked below. Terms and Conditions Privacy Policy ...

  14. Preparation and performance of Ecobras/bentonite biodegrading films

    International Nuclear Information System (INIS)

    Costa, Ana Nery M.; Melo, Nadja M.C.; Canedo, Eduardo L.; Carvalho, Laura H.; Araujo, Arthur R.A.

    2011-01-01

    Compounds based on the biodegradable polymer Ecobras and bentonite clay in its pristine, sonicated, and organically modified with a quaternary ammonium salt forms were prepared as flat films. Clays and compounds were characterized by x-ray diffraction and scanning electron microscopy. Mechanical properties of the films were determined according to pertinent ASTM standards. Reasonable properties, higher than those of the matrix, were obtained with compounds prepared with purified clays and organoclays, particularly for low clay loading. (author)

  15. Experimental study of high-performance cooling system pipeline diameter and working fluid amount

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan; Hrabovsky, Peter; Papučík, Štefan

    2016-03-01

    This work deals with heat transfer resulting from the operation of power electronic components. Heat is removed from the mounting plate, which is the evaporator of the loop thermosyphon to the condenser and by natural convection is transferred to ambient. This work includes proposal of cooling device - loop thermosyphon, with its construct and follow optimization of cooling effect. Optimization proceeds by selecting the quantity of working fluid and selection of diameters vapour line and liquid line of loop thermosyphon.

  16. 3-Dimensional numerical study of cooling performance of a heat sink with air-water flow through mini-channel

    Science.gov (United States)

    Majumder, Sambit; Majumder, Abhik; Bhaumik, Swapan

    2016-07-01

    The present microelectronics market demands devices with high power dissipation capabilities having enhanced cooling per unit area. The drive for miniaturizing the devices to even micro level dimensions is shooting up the applied heat flux on such devices, resulting in complexity in heat transfer and cooling management. In this paper, a method of CPU processor cooling is introduced where active and passive cooling techniques are incorporated simultaneously. A heat sink consisting of fins is designed, where water flows internally through the mini-channel fins and air flows externally. Three dimensional numerical simulations are performed for large set of Reynolds number in laminar region using finite volume method for both developing flows. The dimensions of mini-channel fins are varied for several aspect ratios such as 1, 1.33, 2 and 4. Constant temperature (T) boundary condition is applied at heat sink base. Channel fluid temperature, pressure drop are analyzed to obtain best cooling option in the present study. It has been observed that as the aspect ratio of the channel decreases Nusselt number decreases while pressure drop increases. However, Nusselt number increases with increase in Reynolds number.

  17. Effects of evaporative cooling on reproductive performance and milk production of dairy cows in hot wet conditions

    Science.gov (United States)

    Khongdee, S.; Chaiyabutr, N.; Hinch, G.; Markvichitr, K.; Vajrabukka, C.

    2006-05-01

    Fourteen animals of second and third lactation of Thai Friesian crossbred cows (87.5% Friesian × 12.5% Bos indicus) located at Sakol Nakhon Research and Breeding Centre, Department of Livestock Development, Ministry of Agriculture and Cooperatives, were divided randomly into two groups of seven each to evaluate the effects of evaporative cooling on reproductive and physiological traits under hot, humid conditions. Results indicated that installation of evaporating cooling in the open shed gave a further improvement in ameliorating heat stress in dairy cows in hot-wet environments by utilising the low humidity conditions that naturally occur during the day. The cows housed in an evaporatively cooled environment had both a rectal temperature and respiration rate (39.09°C, 61.39 breaths/min, respectively) significantly lower than that of the non-cooled cows (41.21°C; 86.87 breaths/min). The former group also had higher milk yield and more efficient reproductive performance (pregnancy rate and reduced days open) than the latter group. It is suggested that the non-evaporatively cooled cows did not gain benefit from the naturally lower heat stress during night time.

  18. Thermal performance analysis of heat exchanger for closed wet cooling tower using heat and mass transfer analogy

    International Nuclear Information System (INIS)

    Yoo, Seong Yeon; Han, Kyu Hyun; Kim, Jin Hyuck

    2010-01-01

    In closed wet cooling towers, the heat transfer between the air and external tube surfaces can be composed of the sensible heat transfer and the latent heat transfer. The heat transfer coefficient can be obtained from the equation for external heat transfer of tube banks. According to experimental data, the mass transfer coefficient was affected by the air velocity and spray water flow rate. This study provides the correlation equation for mass transfer coefficient based on the analogy of the heat and mass transfer and the experimental data. The results from this correlation equation showed fairly good agreement with experimental data. The cooling capacity and thermal efficiency of the closed wet cooling tower were calculated from the correlation equation to analyze the performance of heat exchanger for the tower

  19. The Effects of Two Thick Film Deposition Methods on Tin Dioxide Gas Sensor Performance

    OpenAIRE

    Bakrania, Smitesh D.; Wooldridge, Margaret S.

    2009-01-01

    This work demonstrates the variability in performance between SnO2 thick film gas sensors prepared using two types of film deposition methods. SnO2 powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition meth...

  20. Thermodynamic modelling and performance study of an engine waste heat driven adsorption cooling for automotive air-conditioning

    International Nuclear Information System (INIS)

    Ali, Syed Muztuza; Chakraborty, Anutosh

    2015-01-01

    Waste heat from engine can be utilized to drive an adsorption cooling system for air conditioning purposes in the vehicle cabin, which not only improves the fuel economy but also reduces the carbon footprint. It is also important to reduce the size of the adsorption bed to adopt the adsorption technology for air-conditioning applications in passenger cars, buses and trucks or even trains. In this article, we present a two stage indirect exhaust heat recovery system of automotive engine employing an effective lumped parameter model to simulate the dynamic behaviors of an adsorption chiller that ranges from the transient to the cyclic steady states. The thermodynamic framework of adsorption chiller is developed from the rigor of mass and energy balances of each component of the system and experimentally confirmed isotherms and kinetics data of various adsorbent–adsorbate pairs. The performance factors are calculated in terms of COP (Coefficient of Performance) and SCP (Specific Cooling Power) for different operating parameters such as cycle time, exhaust gas temperatures, cooling water temperatures and flow rates. From the simulation results, it is found that the exhaust energy of a six cylinder 3000 cc private car is able to produce nearly 3 kW of cooling power for the car cabin. It is also observed that the driving heat source temperature does not remain constant throughout the cycle time unlike the conventional adsorption chiller, and the hot water temperatures as driving source vary from 65 to 95 °C. CaCl 2 -in-silica gel–water system is found better in terms of COP and SCP as compared with other adsorbents – water systems. - Highlights: • Adsorption cooling for car air conditioning. • Thermodynamic frameworks with adsorption isotherms and kinetics. • Various adsorbents such as silica gel, zeolites (AQSOA-Z01, Z-02), CaCl 2 -in-silica gel are tested. • Cooling power for car cabin employing waste heat recovery.

  1. Thermodynamic study of the effects of ambient air conditions on the thermal performance characteristics of a closed wet cooling tower

    International Nuclear Information System (INIS)

    Papaefthimiou, V.D.; Rogdakis, E.D.; Koronaki, I.P.; Zannis, T.C.

    2012-01-01

    A thermodynamic model was developed and used to assess the sensitivity of thermal performance characteristics of a closed wet cooling tower to inlet air conditions. In the present study, three cases of different ambient conditions are considered: In the first case, the average mid-winter and mid-summer conditions as well as the extreme case of high temperature and relative humidity, in Athens (Greece) during summer are considered according to the Greek Regulation for Buildings Energy Performance. In the second case, the varied inlet air relative humidity while the inlet air dry bulb temperature remains constant were taken into account. In the last case, the effects on cooling tower thermal behaviour when the inlet air wet bulb temperature remains constant were examined. The proposed model is capable of predicting the variation of air thermodynamic properties, sprayed water and serpentine water temperature inside the closed wet cooling tower along its height. The reliability of simulations was tested against experimental data, which were obtained from literature. Thus, the proposed model could be used for the design of industrial and domestic applications of conventional air-conditioning systems as well as for sorption cooling systems with solid and liquid desiccants where closed wet cooling towers are used for precooling the liquid solutions. The most important result of this theoretical investigation is that the highest fall of serpentine water temperature and losses of sprayed water are observed for the lowest value of inlet wet bulb temperature. Hence, the thermal effectiveness, which is associated with the temperature reduction of serpentine water as well as the operational cost, which is related to the sprayed water loss due to evaporation, of a closed wet cooling tower depend predominantly on the degree of saturation of inlet air.

  2. 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.

  3. Comparative study of the performance of the M-cycle counter-flow and cross-flow heat exchangers for indirect evaporative cooling – Paving the path toward sustainable cooling of buildings

    International Nuclear Information System (INIS)

    Zhan, Changhong; Duan, Zhiyin; Zhao, Xudong; Smith, Stefan; Jin, Hong; Riffat, Saffa

    2011-01-01

    This paper provides a comparative study of the performance of cross-flow and counter-flow M-cycle heat exchangers for dew point cooling. It is recognised that evaporative cooling systems offer a low energy alternative to conventional air conditioning units. Recently emerged dew point cooling, as the renovated evaporative cooling configuration, is claimed to have much higher cooling output over the conventional evaporative modes owing to use of the M-cycle heat exchangers. Cross-flow and counter-flow heat exchangers, as the available structures for M-cycle dew point cooling processing, were theoretically and experimentally investigated to identify the difference in cooling effectiveness of both under the parallel structural/operational conditions, optimise the geometrical sizes of the exchangers and suggest their favourite operational conditions. Through development of a dedicated computer model and case-by-case experimental testing and validation, a parametric study of the cooling performance of the counter-flow and cross-flow heat exchangers was carried out. The results showed the counter-flow exchanger offered greater (around 20% higher) cooling capacity, as well as greater (15%–23% higher) dew-point and wet-bulb effectiveness when equal in physical size and under the same operating conditions. The cross-flow system, however, had a greater (10% higher) Energy Efficiency (COP). As the increased cooling effectiveness will lead to reduced air volume flow rate, smaller system size and lower cost, whilst the size and cost are the inherent barriers for use of dew point cooling as the alternation of the conventional cooling systems, the counter-flow system is considered to offer practical advantages over the cross-flow system that would aid the uptake of this low energy cooling alternative. In line with increased global demand for energy in cooling of building, largely by economic booming of emerging developing nations and recognised global warming, the research

  4. Ventilative Cooling

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols; Kolokotroni, Maria

    This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state-of-the-art of ventil......This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state......-of-the-art of ventilative cooling potentials and limitations, its consideration in current energy performance regulations, available building components and control strategies and analysis methods and tools. In addition, the report provides twenty six examples of operational buildings using ventilative cooling ranging from...

  5. Performance of the Lead-Alloy-Cooled Reactor Concept Balanced for Actinide Burning and Electricity Production

    International Nuclear Information System (INIS)

    Hejzlar, Pavel; Davis, Cliff B.

    2004-01-01

    A lead-bismuth-cooled fast reactor concept targeted for a balanced mission of actinide burning and low-cost electricity production is proposed and its performance analyzed. The design explores the potential benefits of thorium-based fuel in actinide-burning cores, in particular in terms of the reduction of the large reactivity swing and enhancement of the small Doppler coefficient typical of fertile-free actinide burners. Reduced electricity production cost is pursued through a longer cycle length than that used for fertile-free burners and thus a higher capacity factor. It is shown that the concept can achieve a high transuranics destruction rate, which is only 20% lower than that of an accelerator-driven system with fertile-free fuel. The small negative fuel temperature reactivity coefficient, small positive coolant temperature reactivity coefficient, and negative core radial expansion coefficient provide self-regulating characteristics so that the reactor is capable of inherent shutdown during major transients without scram, as in the Integral Fast Reactor. This is confirmed by thermal-hydraulic analysis of several transients without scram, including primary coolant pump trip, station blackout, and reactivity step insertion, which showed that the reactor was able to meet all identified thermal limits. However, the benefits of high actinide consumption and small reactivity swing can be attained only if the uranium from the discharged fuel is separated and not recycled. This additional uranium separation step and thorium reprocessing significantly increase the fuel cycle costs. Because the higher fuel cycle cost has a larger impact on the overall cost of electricity than the savings from the higher capacity factor afforded through use of thorium, this concept appears less promising than the fertile-free actinide burners

  6. Performance of the Lead-Alloy Cooled Concept Balanced for Actinide Burning and Electricity Production

    International Nuclear Information System (INIS)

    Pavel Hejzlar; Cliff Davis

    2004-01-01

    A lead-bismuth-cooled fast reactor concept targeted for a balanced mission of actinide burning and low-cost electricity production is proposed and its performance analyzed. The design explores the potential benefits of thorium-based fuel in actinide-burning cores, in particular in terms of the reduction of the large reactivity swing and enhancement of the small Doppler coefficient typical of fertile-free actinide burners. Reduced electricity production cost is pursued through a longer cycle length than that used for fertile-free burners and thus a higher capacity factor. It is shown that the concept can achieve a high transuranics destruction rate, which is only 20% lower than that of an accelerator-driven system with fertile-free fuel. The small negative fuel temperature reactivity coefficient, small positive coolant temperature reactivity coefficient, and negative core radial expansion coefficient provide self-regulating characteristics so that the reactor is capable of inherent shutdown during major transients without scram, as in the Integral Fast Reactor. This is confirmed by thermal-hydraulic analysis of several transients without scram, including primary coolant pump trip, station blackout, and reactivity step insertion, which showed that the reactor was able to meet all identified thermal limits. However, the benefits of high actinide consumption and small reactivity swing can be attained only if the uranium from the discharged fuel is separated and not recycled. This additional uranium separation step and thorium reprocessing significantly increase the fuel cycle costs. Because the higher fuel cycle cost has a larger impact on the overall cost of electricity than the savings from the higher capacity factor afforded through use of thorium, this concept appears less promising than the fertile-free actinide burners

  7. Monolayer-Mediated Growth of Organic Semiconductor Films with Improved Device Performance.

    Science.gov (United States)

    Huang, Lizhen; Hu, Xiaorong; Chi, Lifeng

    2015-09-15

    Increased interest in wearable and smart electronics is driving numerous research works on organic electronics. The control of film growth and patterning is of great importance when targeting high-performance organic semiconductor devices. In this Feature Article, we summarize our recent work focusing on the growth, crystallization, and device operation of organic semiconductors intermediated by ultrathin organic films (in most cases, only a monolayer). The site-selective growth, modified crystallization and morphology, and improved device performance of organic semiconductor films are demonstrated with the help of the inducing layers, including patterned and uniform Langmuir-Blodgett monolayers, crystalline ultrathin organic films, and self-assembled polymer brush films. The introduction of the inducing layers could dramatically change the diffusion of the organic semiconductors on the surface and the interactions between the active layer with the inducing layer, leading to improved aggregation/crystallization behavior and device performance.

  8. Thermal-hydraulic performance of a multiple jet cooling module with a concave dimple array in a helium-cooled divertor

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hyo-Yeon; Kim, Kwang-Yong, E-mail: kykim@inha.ac.kr

    2017-01-15

    A numerical study was performed to evaluate the thermal-hydraulic performance of a finger type cooling module, where multiple jets impinge on the surface with concave dimples, in the divertor of a nuclear fusion reactor. Conjugate heat transfer was analyzed in both the solid and fluid domains using three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. The computational domain consisted of a single fluid domain and three solid domains: tile, thimble, and cartridge. The numerical results for the temperature variation on the tile were validated in comparison with the experimental data. A parametric study was performed with two design variables, the ratios of dimple diameter and dimple height to the nozzle diameter, and two dimple arrays (inline and staggered arrays). The parametric study showed that the heat transfer rate was increased by up to 2.62% by introducing concave dimples, and that the heat transfer and pressure drop performances increased with increasing diameter and height of the dimples for a specified dimple array.

  9. Simultaneous effects of water spray and crosswind on performance of natural draft dry cooling tower

    Directory of Open Access Journals (Sweden)

    Ahmadikia Hossein

    2013-01-01

    Full Text Available To investigate the effect of water spray and crosswind on the effectiveness of the natural draft dry cooling tower (NDDCT, a three-dimensional model has been developed. Efficiency of NDDCT is improved by water spray system at the cooling tower entrance for high ambient temperature condition with and without crosswind. The natural and forced heat convection flow inside and around the NDDCT is simulated numerically by solving the full Navier-Stokes equations in both air and water droplet phases. Comparison of the numerical results with one-dimensional analytical model and the experimental data illustrates a well-predicted heat transfer rate in the cooling tower. Applying water spray system on the cooling tower radiators enhances the cooling tower efficiency at both no wind and windy conditions. For all values of water spraying rate, NDDCTs operate most effectively at the crosswind velocity of 3m/s and as the wind speed continues to rise to more than 3 m/s up to 12 m/s, the tower efficiency will decrease by approximately 18%, based on no-wind condition. The heat transfer rate of radiator at wind velocity 10 m/s is 11.5% lower than that of the no wind condition. This value is 7.5% for water spray rate of 50kg/s.

  10. Performance comparison of metallic, actinide burning fuel in lead-bismuth and sodium cooled fast reactors

    International Nuclear Information System (INIS)

    Weaver, K.D.; Herring, J.S.; Macdonald, P.E.

    2001-01-01

    Various methods have been proposed to ''incinerate'' or ''transmute'' the current inventory of transuranic waste (TRU) that exits in spent light-water-reactor (LWR) fuel, and weapons plutonium. These methods include both critical (e.g., fast reactors) and non-critical (e.g., accelerator transmutation) systems. The work discussed here is part of a larger effort at the Idaho National Engineering and Environmental Laboratory (INEEL) and at the Massachusetts Institute of Technology (MIT) to investigate the suitability of lead and lead-alloy cooled fast reactors for producing low-cost electricity as well as for actinide burning. The neutronics of non fertile fuel loaded with 20 or 30-wt% light water reactor (LWR) plutonium plus minor actinides for use in a lead-bismuth cooled fast reactor are discussed in this paper, with an emphasis on the fuel cycle life and isotopic content. Calculations show that the average actinide burn rate is similar for both the sodium and lead-bismuth cooled cases ranging from -1.02 to -1.16 g/MWd, compared to a typical LWR actinide generation rate of 0.303 g/MWd. However, when using the same parameters, the sodium-cooled case went subcritical after 0.2 to 0.8 effective full power years, and the lead-bismuth cooled case ranged from 1.5 to 4.5 effective full power years. (author)

  11. Chemically Crosslinked Hydrogel Film Leads to Integrated Flexible Supercapacitors with Superior Performance.

    Science.gov (United States)

    Wang, Kai; Zhang, Xiong; Li, Chen; Sun, Xianzhong; Meng, Qinghai; Ma, Yanwei; Wei, Zhixiang

    2015-12-02

    A high-strength poly(vinyl alcohol) chemical hydrogel (PCH) film is prepared by coupling covalent crosslinking with a film-casting process. Conducting polyaniline (PANI) is then embedded in the PCH film by in situ growth to form a composite film with a PANI-hydrogel-PANI configuration, which leads to a new conceptual flexible supercapacitor with all-in-one configuration that exhibits superior electrochemical performance and mechanical flexibility. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Development and validation of a full-range performance analysis model for a three-spool gas turbine with turbine cooling

    International Nuclear Information System (INIS)

    Song, Yin; Gu, Chun-wei; Ji, Xing-xing

    2015-01-01

    The performance analysis of a gas turbine is important for both its design and its operation. For modern gas turbines, the cooling flow introduces a noteworthy thermodynamic loss; thus, the determination of the cooling flow rate will clearly influence the accuracy of performance calculations. In this paper, a full-range performance analysis model is established for a three-spool gas turbine with an open-circuit convective blade cooling system. A hybrid turbine cooling model is embedded in the analysis to predict the amount of cooling air accurately and thus to remove the errors induced by the relatively arbitrary value of cooling air requirements in the previous research. The model is subsequently used to calculate the gas turbine performance; the calculation results are validated with detailed test data. Furthermore, multistage conjugate heat transfer analysis is performed for the turbine section. The results indicate that with the same coolant condition and flow rate as those in the performance analysis, the blade metal has been effectively cooled; in addition, the maximum temperature predicted by conjugate heat transfer analysis is close to the corresponding value in the cooling model. Hence, the present model provides an effective tool for analyzing the performance of a gas turbine with cooling. - Highlights: • We established a performance model for a gas turbine with convective cooling. • A hybrid turbine cooling model is embedded in the performance analysis. • The accuracy of the model is validated with detailed test data of the gas turbine. • Conjugate heat transfer analysis is performed for the turbine for verification

  13. Showing and telling : film heritage institutes and their performance of public accountability

    NARCIS (Netherlands)

    de Klerk, N.H.

    2015-01-01

    This PhD expands on 12 previously published film historical and -archival articles and essays. An extensive introductory text was written to string these articles and essays together and forge them into an argument for improving the performance of film heritage institutes vis-a-vis the public. In

  14. Improving the Performance Attributes of Plug-in Hybrid Electric Vehicles in Hot Climates through Key-Off Battery Cooling

    Directory of Open Access Journals (Sweden)

    Sina Shojaei

    2017-12-01

    Full Text Available Ambient conditions can have a significant impact on the average and maximum temperature of the battery of electric and plug-in hybrid electric vehicles. Given the sensitivity of the ageing mechanisms of typical battery cells to temperature, a significant variability in battery lifetime has been reported with geographical location. In addition, high battery temperature and the associated cooling requirements can cause poor passenger thermal comfort, while extreme battery temperatures can negatively impact the power output of the battery, limiting the available electric traction torque. Avoiding such issues requires enabling battery cooling even when the vehicle is parked and not plugged in (key-off, but the associated extra energy requirements make applying key-off cooling a non-trivial decision. In this paper, a representative plug-in parallel hybrid electric vehicle model is used to simulate a typical 24-h duty cycle to quantify the impact of hot ambient conditions on three performance attributes of the vehicle: the battery lifetime, passenger thermal comfort and fuel economy. Key-off cooling is defined as an optimal control problem in view of the duty cycle of the vehicle. The problem is then solved using the dynamic programming method. Controlling key-off cooling through this method leads to significant improvements in the battery lifetime, while benefiting the fuel economy and thermal comfort attributes. To further improve the battery lifetime, partial charging of the battery is considered. An algorithm is developed that determines the optimum combination of key-off cooling and the level of battery charge. Simulation results confirm the benefits of the proposed method.

  15. Performance evaluation of an indirect pre-cooling evaporative heat exchanger operating in hot and humid climate

    International Nuclear Information System (INIS)

    Cui, X.; Chua, K.J.; Islam, M.R.; Ng, K.C.

    2015-01-01

    Highlights: • An IEHX is introduced as a pre-cooling unit for humid tropical climate. • A computational model is developed to investigate the performance of IEHX. • The air treatment process with condensation from the product air is studied. • The hybrid system shows an appreciable energy saving potential. - Abstract: A hybrid system, that combines an indirect evaporative heat exchanger (IEHX) and a vapor compression system, is introduced for humid tropical climate application. The chief purpose of the IEHX is to pre-cool the incoming air for vapor compression system. In the IEHX unit, the outdoor humid air in the product channel may potentially condense when heat is exchanged with the room exhaust air. A computational model has been developed to theoretically investigate the performance of an IEHX with condensation from the product air by employing the room exhaust air as the working air. We validated the model by comparing its temperature distribution and predicted heat flux against experimental data acquired from literature sources. The numerical model showed good agreement with the experimental findings with maximum average discrepancy of 9.7%. The validated model was employed to investigate the performance of two types of IEHX in terms of the air treatment process, temperature and humidity distribution, cooling effectiveness, cooling capacity, and energy consumption. Simulation results have indicated that the IEHX unit is able to fulfill 47% of the cooling load for the outdoor humid air while incurring a small amount of fan power. Consequently, the hybrid system is able to realize significant energy savings

  16. Effect of jet nozzle geometry on flow and heat transfer performance of vortex cooling for gas turbine blade leading edge

    International Nuclear Information System (INIS)

    Du, Changhe; Li, Liang; Wu, Xin; Feng, Zhenping

    2016-01-01

    Highlights: • We establish a suitable vortex chamber model for gas turbine blade leading edge. • Mechanism of vortex cooling is further discussed and presented. • Influences of jet nozzle geometry on vortex cooling characteristics are researched. • This paper focuses on assessment of flow field and thermal performance for different jet nozzle aspect ratio and area. - Abstract: In this paper, 3D viscous steady Reynolds Averaged Navier–Stokes (RANS) equations are utilized to investigate the influence of jet nozzle geometry on flow and thermal behavior of vortex cooling for gas turbine blades. Comparison between calculation with different turbulence models and the experimental data is conducted, and results show that the standard k-ω model provides the best accuracy. The grid independence analysis is performed to obtain the proper mesh number. First, the mechanism of vortex cooling is further discussed, and the pronounced impact of kinetic turbulence intensity, thin thermal boundary layer, violent radial convection and complex vortices on enhanced heat transfer performance is confirmed. Then, seven jet nozzle aspect ratios and seven jet nozzle to chamber cross section area ratios are selected to research the flow field and thermal characteristics of vortex cooling focusing on the streamline, static pressure ratio, total pressure loss ratio and Nusselt number. It is presented that the jet nozzle aspect ratio and jet nozzle to chamber cross section area ratio both impose a significant effect on the flow and thermal parameters. The averaged Nusselt number decreases at first and then increases with the increasing jet nozzle aspect ratio, reaching highest when aspect ratio equals to 1. The effect of area ratio on averaged Nusselt number is complex. Finally, the heat transfer results in this study are compared with other previous works. Results indicate that good agreement with previous data is achieved, and the enhanced thermal behavior may be acquired by

  17. Cost and performance optimization of natural draft dry cooling towers using genetic algorithm. Paper no. IGEC-1-002

    International Nuclear Information System (INIS)

    Shokuhmand, H.; Ghaempanah, B.

    2005-01-01

    In this paper the cost - performance optimization of natural draft dry cooling towers with specific kind of heat exchangers, known as Forgo T60 has been investigated. These cooling towers are used in combined and steam cycle power plants. The optimization has been done using genetic algorithm. The objective function has two parts, which are minimizing the cost and maximizing the performance. In the first part the geometrical and operating parameters are defined and for the next part the performance of the designed tower for different ambient temperatures during a year is calculated considering the characteristic curve of the turbine. The applied genetic algorithm has been tuned up using the data of some working power cycles. The results show it is possible to find an optimum for all design parameters; however it is very dependent on how exact the cost analysis is. (author)

  18. Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

    Energy Technology Data Exchange (ETDEWEB)

    Khun, N.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, E., E-mail: MEJLiu@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2011-03-15

    Research highlights: {yields} Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. {yields} The graphitization of the films increased with increased film thickness. {yields} The wear resistance of the films increased though their adhesion strength decreased. {yields} The corrosion potentials of the films shifted to more negative values. {yields} However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp{sup 2} bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

  19. Electrochemically synthesized nanocrystalline spinel thin film for high performance supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vinay [Carbon Technology Unit, Engineering Materials Division, National Physical Laboratory, New-Delhi, 110012 (India); Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka, 816-8580 (Japan); Japan Science and Technology Agency, Kawaguchi-shi, Saitama, 332-0012 (Japan); Gupta, Shubhra; Miura, Norio [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka, 816-8580 (Japan)

    2010-06-01

    Spinels are not known for their supercapacitive nature. Here, we have explored electrochemically synthesized nanostructured NiCo{sub 2}O{sub 4} spinel thin-film electrode for electrochemical supercapacitors. The nanostructured NiCo{sub 2}O{sub 4} spinel thin film exhibited a high specific capacitance value of 580 F g{sup -1} and an energy density of 32 Wh kg{sup -1} at the power density of 4 kW kg{sup -1}, accompanying with good cyclic stability. (author)

  20. Performance investigation of ground cooling for the airbus A380 in the United Arab Emirates

    International Nuclear Information System (INIS)

    Aranjo, Brendan Savio; Hughes, Ben Richard; Chaudry, Hassam Nasarullah

    2012-01-01

    A combination of the United Arab Emirates (UAE) climate and the increased size of the super jumbo, Airbus A380, have exceeded the working capacity for current ground cooling techniques. These are evident when the aircraft is being prepared for flight and when in the hanger under maintenance with internal cabin temperatures reported at above 30 °C. The existing system used, delivers air at 11.6 °C after which the cabin temperature is still at a high temperature of 31 °C and unable to cool down due to the temperature rises caused by climate conditions and heat dissipation from the electronics in the cabin. The CFD based temperature profile results highlighted that a decrease in inlet temperature to −18 °C at a constant pressure and mass flow rate is sufficient to provide efficient cooling to the cabin at 22 °C. Boundary conditions are determined to specify a new effective cooling system and resolve the ground cooling issue. - Highlights: ► Computational Fluid Dynamics (CFD) analysis was carried out on the aircraft cabin. ► Existing system delivers air at 11.6 °C. ► Cabin temperature is still at a high temperature of 31 °C. ► The inlet temperature of the air should be −18 °C using the existing system. ► Air is delivered at 6.5 kg/s, to cool the cabin to a comfortable temperature of 22 °C.

  1. Analysis of the cool down related cavity performance of the European XFEL vertical acceptance tests

    Energy Technology Data Exchange (ETDEWEB)

    Wenskat, Marc; Schaffran, J.

    2017-09-15

    For the European X-Ray Free Electron Laser (XFEL) cavity production, the cold radio-frequency (RF) test of the cavities at 2 K after delivery from the two vendors was the mandatory acceptance test. It has been previously reported, that the cool down dynamics of a cavity across T{sub c} has a significant influence on the observed intrinsic quality factor Q{sub 0}, which is a measure of the losses on the inner cavity surface. A total number of 367 cool downs is used to analyze this correlation and we show that such a correlation is not observed during the European XFEL cavity production.

  2. Development of peelable films for decontamination and their performances

    International Nuclear Information System (INIS)

    Yang Enbo; Xu Baolan; Zhao Xiuyan

    1990-01-01

    Two kinds of peelable films have been developed which can be coated on surface contaminated by radioactivity for decontamination purposes. Very high levels of radioactive decontamination, especially on smooth surface, are obtained after one application. 90-99% decontamination based on initial activity can be obtained for stainless steel, PVC floor and glass

  3. Performance of polymeric films based thermoplastic starch and organophilic clay

    International Nuclear Information System (INIS)

    Cipriano, P.B.; Costa, A.N.M.; Araujo, S.S.; Araujo, A.R.A.; Canedo, E.L.; Carvalho, L.H.

    2010-01-01

    The aim of this work was the development and investigation of the properties of flat films of LDPE/corn thermoplastic starch (TPS). A bentonite clay (Argel) was organophilized and characterized by XRD. This clay (1%) in both pristine and organophilic forms was added to the matrix (LDPE) and to LDPE/TPS systems with TPS contents varying from 5-20% w/w. The films manufactured (LDPE, LDPE/Clay, LDPE/TPS, LDPE/TPS/Clay) were characterized. Results indicate that water vapor permeability is dependent and increases with TPS content which was attributed to the higher affinity of water by TPS. TPS and Clay addition to LDPE led to significant changes in film properties with respect to the neat LDPE. In general,tensile and perforation forces increased with clay and TPS contents; the strength of thermo sealed films lowered with natural clay addition and increased with TPS and organoclay incorporation and, in general, dynamic friction coefficient decrease with organoclay and TPS addition. Best overall properties were obtained for the systems containing the organoclay and optimal properties were achieved for the 5%TPS10 LDPE1% ANO system. (author)

  4. Performance investigation of a waste heat-driven 3-bed 2-evaporator adsorption cycle for cooling and desalination

    KAUST Repository

    Thu, Kyaw

    2016-06-13

    Environment-friendly adsorption (AD) cycles have gained much attention in cooling industry and its applicability has been extended to desalination recently. AD cycles are operational by low-temperature heat sources such as exhaust gas from processes or renewable energy with temperatures ranging from 55 °C to 85 °C. The cycle is capable of producing two useful effects, namely cooling power and high-grade potable water, simultaneously. This article discusses a low temperature, waste heat-powered adsorption (AD) cycle that produces cooling power at two temperature-levels for both dehumidification and sensible cooling while providing high-grade potable water. The cycle exploits faster kinetics for desorption process with one adsorber bed under regeneration mode while full utilization of the uptake capacity by adsorbent material is achieved employing two-stage adsorption via low-pressure and high-pressure evaporators. Type A++ silica gel with surface area of 863.6 m2/g and pore volume of 0.446 cm3/g is employed as adsorbent material. A comprehensive numerical model for such AD cycle is developed and the performance results are presented using assorted hot water and cooling water inlet temperatures for various cycle time arrangements. The cycle is analyzed in terms of key performance indicators i.e.; the specific cooling power (SCP), the coefficient of performance (COP) for both evaporators and the overall system, the specific daily water production (SDWP) and the performance ratio (PR). Further insights into the cycle performance are scrutinized using a Dühring diagram to depict the thermodynamic states of the processes as well as the vapor uptake behavior of adsorbent. In the proposed cycle, the adsorbent materials undergo near saturation conditions due to the pressurization effect from the high pressure evaporator while faster kinetics for desorption process is exploited, subsequently providing higher system COP, notably up to 0.82 at longer cycle time while the

  5. Conceptual development of a building-integrated photovoltaic–radiative cooling system and preliminary performance analysis in Eastern China

    International Nuclear Information System (INIS)

    Zhao, Bin; Hu, Mingke; Ao, Xianze; Pei, Gang

    2017-01-01

    Highlights: •A specific spectral characteristic for both PV and RC was proposed. •The PV/RC hybrid system based on spectral characteristic is original. •A thermal model of the system was established and the performance was analyzed. •The performance comparison with the conventional PV system was conducted. •The system shows considerable performance for both PV and RC. -- Abstract: Building-integrated photovoltaic/thermal (BIPV/T) technology has been receiving considerable research attention because of its ability to generate electricity and thermal energy simultaneously. However, space cooling is crucial for buildings in hot regions where space heating is of little use. This study proposed a building-integrated photovoltaic–radiative cooling system (BIPV–RC) that can generate electricity via photovoltaic (PV) conversion during daytime and generate cooling energy via radiative cooling (RC) during nighttime to satisfy the demand in such areas. The selective plate, which is the main component of the BIPV–RC system, exhibits high spectral absorptivity (emissivity) in the PV conversion band of crystalline silicon solar cells and in the atmospheric window band (i.e., 0.3–1.1 μm and 8–13 μm), as well as low spectral absorptivity (emissivity) in other bands. A quasi-steady-state mathematical model was built, and its performance under realistic ambient conditions was analyzed. The electrical efficiencies of the BIPV–RC and conventional BIPV systems were then compared under different solar radiations. Comparison results show that the annual electricity production and cooling energy gain of the BIPV–RC system in Hefei reached 156.74 kW h m −2 (equivalent to 564.26 MJ m −2 ) and 579.91 MJ m −2 , respectively. The total electricity production and cooling energy gain of this system are 96.96% higher than those of the BIPV system. Parametric studies show that the precipitable water vapor amount has remarkable effects on the nocturnal RC performance

  6. Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion

    Energy Technology Data Exchange (ETDEWEB)

    Cornejo, J. M.; Colombano, M.; Doménech, J.; Rodríguez, D., E-mail: danielrodriguez@ugr.es [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, 18071 Granada (Spain); Block, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Helmholtz-Institut Mainz, 55099 Mainz (Germany); Institut für Kernchemie, University of Mainz, 55099 Mainz (Germany); Delahaye, P. [Grand Accélérateur National d’Ions Lourds, 14000 Caen (France)

    2015-10-15

    A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single {sup 40}Ca{sup +} ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on {sup 40}Ca{sup +} ions, starting from large clouds and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.

  7. Effects of acoustic ceiling units on the cooling performance of thermally activated building systems (TABS)

    DEFF Research Database (Denmark)

    Lacarte, Luis Marcos Domínguez; Rage, Niels; Kazanci, Ongun Berk

    2017-01-01

    Europe, with a building stock responsible for about 40% of the total energy use, needs to reduce the primary energy use in buildings in order to meet the 2020 energy targets of the European Union. High temperature cooling and low temperature heating systems, and as an example, Thermally Activated...

  8. Optomechanical performance of 3D-printed mirrors with embedded cooling channels and substructures

    Science.gov (United States)

    Mici, Joni; Rothenberg, Bradley; Brisson, Erik; Wicks, Sunny; Stubbs, David M.

    2015-09-01

    Advances in 3D printing technology allow for the manufacture of topologically complex parts not otherwise feasible through conventional manufacturing methods. Maturing metal and ceramic 3D printing technologies are becoming more adept at printing complex shapes, enabling topologically intricate mirror substrates. One application area that can benefit from additive manufacturing is reflective optics used in high energy laser (HEL) systems that require materials with a low coefficient of thermal expansion (CTE), high specific stiffness, and (most importantly) high thermal conductivity to effectively dissipate heat from the optical surface. Currently, the limits of conventional manufacturing dictate the topology of HEL optics to be monolithic structures that rely on passive cooling mechanisms and high reflectivity coatings to withstand laser damage. 3D printing enables the manufacture of embedded cooling channels in metallic mirror substrates to allow for (1) active cooling and (2) tunable structures. This paper describes the engineering and analysis of an actively cooled composite optical structure to demonstrate the potential of 3D printing on the improvement of optomechanical systems.

  9. The Effect of Variable Gravity on the Cooling Performance of a 16-Nozzle Spray Array

    Science.gov (United States)

    2008-09-01

    Coolants and Capabilities [1]. spray cooling, have been studied in depth and are currently being used on various types of systems. Mudawar [1] presented many...meniscus. Surface modifications could be made to reduce this effect while enhancing overall operability. 58 Bibliography [1] Mudawar , I., “Assessment of

  10. Cool Farm Tool – Potato: Model Description and Performance of Four Production Systems

    NARCIS (Netherlands)

    Haverkort, A.J.; Hillier, J.G.

    2011-01-01

    The Cool Farm Tool – Potato (CFT-Potato) is a spreadsheet programme that allows the calculation of the amount of CO2 equivalents that it costs to produce 1 t of potato. The spreadsheet was adapted from an original generic version of the tool, and completed for potato production in diverse production

  11. Toward Cooling Uniformity: Investigation of Spiral, Sweeping Holes, and Unconventional Cooling Paradigms

    Science.gov (United States)

    Shyam, Vikram; Thurman, Douglas R.; Poinsatte, Philip E.; Ameri, Ali A.; Culley, Dennis E.

    2018-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. Ways to quantify the efficacy of novel cooling holes that are asymmetric, not uniformly spaced or that show variation from hole to hole are presented. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and square holes. A patent-pending spiral hole design showed the highest potential of the nondiffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing ratios of 1.0, 1.5, 2.0, and 2.5 at a density ratio of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS. A section on ideas for future work is included that addresses issues of quantifying cooling uniformity and provides some ideas for changing the way we think about cooling such as changing the direction of cooling or coupling acoustic devices to cooling holes to regulate frequency.

  12. Modelling the performance parameters of a horizontal falling film absorber with aqueous (lithium, potassium, sodium) nitrate solution using artificial neural networks

    International Nuclear Information System (INIS)

    Álvarez, María E.; Hernández, José A.; Bourouis, Mahmoud

    2016-01-01

    An ANN (artificial neural network) model was developed to determine the efficiency parameters of a horizontal falling film absorber at operating conditions of interest for absorption cooling systems. The aqueous nitrate solution LiNO_3 + KNO_3 + NaNO_3 with salt mass percentages of 53%, 28% and 19%, respectively, was used as a working fluid. The authors created the ANN from the database they had compiled with the results of experiments that they had performed in a set-up designed and built for this purpose. The ANN structure consisted of 6 input variables: inlet solution and cooling water temperatures, cooling water and solution mass flow rates, absorber pressure and inlet solution concentration; 4 output variables which facilitated the assessment of the performance of the absorber: heat and mass transfer coefficients, absorption mass flux and the degree of subcooling of the solution leaving the absorber. The hidden layer contained 9 neurons which were determined by training and test procedures. The results showed that the deviation between the experimental data and the estimated values was well adjusted. This indicated that the ANN model was an effective tool for predicting the efficiency parameters of the absorber. The solution flow rate was also observed to be the most significant operating variable which affected the performance of the absorber. - Highlights: • An ANN was developed to predict the efficiency parameters of a falling film absorber. • The ANN was created using a database corresponding to a triple-effect absorption chiller. • The ANN predicts the efficiency parameters of falling film absorbers with r"2 > 0.95. • The solution flow rate is the variable that most affects the performance of the absorber.

  13. Friction and wear performance of diamond-like carbon films grown in various source gas plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Nilufer, I.B.; Eryilmaz, O.L.; Beschliesser, M.; Fenske, G.R. [Argonne National Lab., IL (United States). Energy Technology Div.

    1999-11-01

    In this study, we investigated the effects of various source gases (methane, ethane, ethylene, and acetylene) on the friction and wear performance of diamond-like carbon (DLC) films prepared in a plasma-enhanced chemical vapor deposition (PECVD) system. Films were deposited on AISI H13 steel substrates and tested in a pin-on-disk machine against DLC-coated M50 balls in dry nitrogen. We found a close correlation between friction coefficient and source gas composition. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios exhibited lower friction coefficients and a higher wear resistance than films grown in source gases with lower hydrogen-to-carbon (H/C) ratios. The lowest friction coefficient (0.014) was achieved with a film derived from methane with an H/C ratio of 4, whereas the coefficient of films derived from acetylene (H/C=1) was 0.15. Similar correlations were observed for wear rates. Specifically, films derived from gases with lower H/C values were worn out, and the substrate material was exposed, whereas films from methane and ethane remained intact and wore at rates that were almost two orders of magnitude lower than films obtained from acetylene. (orig.)

  14. Temperature Field Accurate Modeling and Cooling Performance Evaluation of Direct-Drive Outer-Rotor Air-Cooling In-Wheel Motor

    Directory of Open Access Journals (Sweden)

    Feng Chai

    2016-10-01

    Full Text Available High power density outer-rotor motors commonly use water or oil cooling. A reasonable thermal design for outer-rotor air-cooling motors can effectively enhance the power density without the fluid circulating device. Research on the heat dissipation mechanism of an outer-rotor air-cooling motor can provide guidelines for the selection of the suitable cooling mode and the design of the cooling structure. This study investigates the temperature field of the motor through computational fluid dynamics (CFD and presents a method to overcome the difficulties in building an accurate temperature field model. The proposed method mainly includes two aspects: a new method for calculating the equivalent thermal conductivity (ETC of the air-gap in the laminar state and an equivalent treatment to the thermal circuit that comprises a hub, shaft, and bearings. Using an outer-rotor air-cooling in-wheel motor as an example, the temperature field of this motor is calculated numerically using the proposed method; the results are experimentally verified. The heat transfer rate (HTR of each cooling path is obtained using the numerical results and analytic formulas. The influences of the structural parameters on temperature increases and the HTR of each cooling path are analyzed. Thereafter, the overload capability of the motor is analyzed in various overload conditions.

  15. Environmental influences on the performance of thin film solar cells

    International Nuclear Information System (INIS)

    Gottschalg, Ralph

    2001-01-01

    The response of thin film photovoltaic devices to changes in the environment is not well understood. There are a large number of conflicting reports, reflecting largely the superimposed nature of the environmental effects. A separation of the effects is not often attempted mainly because of the lack of appropriate spectral data. An experimental system has been designed and operated to facilitate the separation of the environmental effects, including spectral effects. This involves measurements in a controlled laboratory environment as well as outdoor monitoring. Furthermore, a number of analysis tools have been developed and tested for their suitability. In order to develop a system model, the applicability of parametric models for thin film devices is probed. The thermal variation of the underlying physical parameters is investigated and problems of describing thin film devices with parametric models are discussed. It is shown that the magnitude of the spectral effects for thin film devices is potentially much more significant than for conventional crystalline silicon devices. This analysis is centred on the primary spectral effect, i.e. it is conducted purely on the basis of available light and does not consider any absorption profiles or device structures. It is also shown that there is a strong daily and seasonal variation in the fraction of the useful light for devices employing a larger band gap. Environmental effects are observed directly from outdoor measurements. It is apparent that many of the reported idiosyncrasies occurring during the operation of thin film devices can be explained simply by including spectral effects. It is possible to show the secondary spectral effect for multi-junction devices, i.e. an effect that depends on the composition of the solar irradiance and not purely on the magnitude of spectrally useful irradiance. This effect impacts mainly on the short circuit current and to some extent on the fill factor. Finally, the findings of

  16. Amorphous Zinc Oxide Integrated Wavy Channel Thin Film Transistor Based High Performance Digital Circuits

    KAUST Repository

    Hanna, Amir; Hussain, Aftab M.; Omran, Hesham; Alshareef, Sarah; Salama, Khaled N.; Hussain, Muhammad Mustafa

    2015-01-01

    High performance thin film transistor (TFT) can be a great driving force for display, sensor/actuator, integrated electronics, and distributed computation for Internet of Everything applications. While semiconducting oxides like zinc oxide (Zn

  17. Relating performance of thin-film composite forward osmosis membranes to support layer formation and structure

    KAUST Repository

    Tiraferri, Alberto; Yip, Ngai Yin; Phillip, William A.; Schiffman, Jessica D.; Elimelech, Menachem

    2011-01-01

    the technology to the point that it is commercially viable. Here, a systematic investigation of the influence of thin-film composite membrane support layer structure on forward osmosis performance is conducted. The membranes consist of a selective polyamide

  18. High-Performance Single-Crystalline Perovskite Thin-Film Photodetector

    KAUST Repository

    Yang, Zhenqian; Deng, Yuhao; Zhang, Xiaowei; Wang, Suo; Chen, Huazhou; Yang, Sui; Khurgin, Jacob; Fang, Nicholas X.; Zhang, Xiang; Ma, Renmin

    2018-01-01

    The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial

  19. Review and evaluation of information on the thermal performance of ultimate heat sinks: spray ponds and cooling ponds

    International Nuclear Information System (INIS)

    Drake, R.L.

    1975-09-01

    A report is presented which identifies and evaluates available information and data useful in validating and improving existing models for the thermal performance of ultimate heat sinks. Included are discussions of the thermal elements of cooling ponds and spray ponds, the available information and data pertinent to the problem, and the requirements and needs for further research and performance data. An outline is presented of the necessary elements required for a performance test of an ultimate heat sink before the system is thermally approved. (auth)

  20. Improving lithium-ion battery performances by adding fly ash from coal combustion on cathode film

    Energy Technology Data Exchange (ETDEWEB)

    Dyartanti, Endah Retno; Jumari, Arif, E-mail: arifjumari@yahoo.com; Nur, Adrian; Purwanto, Agus [Research Group of Battery & Advanced Material, Department of Chemical Engineering, Sebelas Maret University, Jl. Ir. Sutami 36 A Kentingan, Surakarta Indonesia 57126 (Indonesia)

    2016-02-08

    A lithium battery is composed of anode, cathode and a separator. The performance of lithium battery is also influenced by the conductive material of cathode film. In this research, the use of fly ash from coal combustion as conductive enhancer for increasing the performances of lithium battery was investigated. Lithium iron phosphate (LiFePO{sub 4}) was used as the active material of cathode. The dry fly ash passed through 200 mesh screen, LiFePO{sub 4} and acethylene black (AB), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed to form slurry. The slurry was then coated, dried and hot pressed to obtain the cathode film. The ratio of fly ash and AB were varied at the values of 1%, 2%, 3%, 4% and 5% while the other components were at constant. The anode film was casted with certain thickness and composition. The performance of battery lithium was examined by Eight Channel Battery Analyzer, the composition of the cathode film was examined by XRD (X-Ray Diffraction), and the structure and morphology of the anode film was analyzed by SEM (Scanning Electron Microscope). The composition, structure and morphology of cathode film was only different when fly ash added was 4% of AB or more. The addition of 2% of AB on cathode film gave the best performance of 81.712 mAh/g on charging and 79.412 mAh/g on discharging.

  1. A device for emergency cooling visualization

    International Nuclear Information System (INIS)

    Rezende, Hugo Cesar; Ladeira, Luiz Carlos Duarte

    1995-01-01

    A test facility for rewetting experiments, Emergency Cooling Visualization Device, has been erected at CDTN, with the objective of Emergency Cooling visualization device performing visual observations of basic phenomena that occur during the reflood phase of a Loss of Coolant Accident (LOCA), in a Pressurised Water Reactor (PWR), utilizing annular test sections. It permits to film or photograph the advance of a wetting front and the flow and heat transfer conditions. Then it is possible to observe the heat transfer regions and flow zones: steam convection, fog cooling, film boiling, nucleate boiling and fluid convection. Finally, this facility is the first test facility, in the Thermohydraulics Laboratory of CDTN, that uses a indirectly heated fuel rod simulator. (author). 3 refs, 5 figs

  2. Studies on Gas Sensing Performance of Pure and Surface Chrominated Indium Oxide Thick Film