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Experimental Study on heat transfer performance of Pulsating heat Pipe with Refrigerants

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Journal of Thermal Science 2016年第5期25卷 449-453页

作者： WANG Xingyu Institute of Thermal Engineering School of MechanicalElectronic and Control EngineeringBeijing Jiaotong Uni-versityBeijing100044 China Beijing Key Laboratory of Flow and heat transfer of Phase Changing in Micro and Small Scale Beijing 100044China

The effects of different refrigerants on heat transfer performance of pulsating heat pipe(PHP) are investigated *** working temperature of pulsating heat pipe is kept in the range of 20℃-50℃.The startup time of the pulsating heat pipe with refrigerants can be shorter than 4 min,when heating power is in the range of *** startup time decreases with heating *** resistances of PHP with filling ratio 20.55% were obviously larger than those with other filling *** resistance of the PHP with R134a is much smaller than that with R404A and *** indicates that the heat transfer ability of R134a is *** addition,a correlation to predict thermal resistance of PHP with refrigerants was suggested.

关键词： R134a pulsating heat pipe heat transfer performance non-dimensional correlation

Theoretical and experimental research on heat transfer performance of the semi-open heat pipe

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第3期9卷 410-415页

作者： Hua ZHU Bo ZHUAN Jin-jun TAN Rong-hua HONG Institute of Thermal Science and Power Systems Zhejiang University Hangzhou 310027 China

This paper focuses on the heat transfer performance of semi-open heat pipe which is a new type of heat pipe. After analyzing its condensation heat transfer mechanisms theoretically, several semi-open heat pipes in different length ratios and upper hole diameters are studied experimentally and compared with the same dimensions closed heat pipes. Experimental results show that the heat transfer performance of semi-open heat pipe becomes better by increasing heat transfer rate. At the first transitional point, the heat transfer performance of semi-open heat pipe approaches the level of the closed heat pipe. It is suitable to choose upper small hole about 1 mm in diameter and length ratio larger than 0.6 for the semi-open heat pipe.

关键词： Semi-open heat pipe heat transfer performance Closed heat pipe First transitional point

Conceptual design and heat transfer performance of a flat-tile water-cooled divertor target

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Plasma Science and Technology 2021年第9期23卷 194-205页

作者： Lei LI Le HAN Pengfei ZI Lei CAO Tiejun XU Nanyu MOU Zhaoliang WANG Lei YIN Damao YAO Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China

The divertor target components for the Chinese fusion engineering test reactor(CFETR)and the future experimental advanced superconducting tokamak(EAST)need to remove a heat flux of up to20 MW *** view of such a high heat flux removal requirement,this study proposes a conceptual design for a flat-tile divertor target based on explosive welding and brazing *** water-cooled channels with a special thermal transfer structure(TTS)are designed in the heat sink to improve the flat-tile divertor target’s heat transfer performance(HTP).The parametric design and optimization methods are applied to study the influence of the TTS variation parameters,including height(H),width(W*),thickness(T),and spacing(L),on the *** research results show that the flat-tile divertor target’s HTP is sensitive to the TTS parameter changes,and the sensitivity is T>L>W*>*** HTP first increases and then decreases with the increase of T,L,and W*and gradually increases with the increase of *** optimal design parameters are as follows:H=5.5 mm,W*=25.8 mm,T=2.2 mm,and L=9.7 *** HTP of the optimized flat-tile divertor target at different flow speeds and tungsten tile thicknesses is studied using the numerical simulation method.A flat-tile divertor mock-up is developed according to the optimized *** addition,high heat flux(HHF)tests are performed on an electron beam facility to further investigate the mock-up *** numerical simulation calculation results show that the optimized flat-tile divertor target has great potential for handling the steady-state heat load of 20 MW m-2under the tungsten tile thicknessheat transfer efficiency of the flat-tile divertor target with rectangular cooling channels improves by13%and30%compared to that of the flat-tile divertor target with circular cooling channels and the ITER-like monoblock,*** HHF tests indicate that the flat-tile divertor mock-up can successfully withstand

关键词： CFETR heat transfer performance parametric design and optimization HHF tests flat-tile divertor target

Effects of bending on heat transfer performance of axial micro-grooved heat pipe

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Journal of Central South University 2011年第2期18卷 580-586页

作者：蒋乐伦汤勇潘敏强 School of Mechanical and Automotive Engineering South China University of Technology

heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux,which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved heat pipes was analyzed in the vapor pressure drop,the liquid pressure drop and the interaction of the vapor with wick fluid. The bent heat pipes were fabricated and tested from the bending angle,the bending position and the bending radius. The results show that temperature difference and thermal resistance increase while the heat transfer capacity of the heat pipe decreases,with the increase of the bending angles and the bending position closer to the vapor section. However,the effects of bending radius can be ignored. The result agrees well with the predicted equations.

关键词： electronics cooling system axial micro-grooved heat pipe bending heat transfer performance

Numerical study on the heat transfer performance of coaxial shallow borehole heat exchanger

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Energy and Built Environment 2021年第4期2卷 445-455页

作者： Guichen Li Jianzhi Yang Xiaowei Zhu Zhihe Shen Department of Built Environment Hefei University of TechnologyHefeiAnhui 230009China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyangSichuan 621000China Department of Mechanical Engineering Johns Hopkins UniversityBaltimoreMD 21218USA Anhui’s International Joint Research Center on Hydrogen Safety HefeiAnhui 230009China

In the present work,a numerical investigation on the coaxial shallow borehole heat exchanger based on Com-putational Fluid Dynamics(CFD)technique in Hefei city of China has been *** effects of design parameters,including inlet flow rate,inlet fluid temperature,inner pipe material and outer pipe diameter,on the heat transfer performance were systematically ***,the thermal behavior along the pipe has been carefully examined with focus on the thermal short-circuiting *** the fluid inlet velocity is less than the critical value,the turbulence intensity increases and the Nusselt number increases with the inlet flow rate ***,there is sufficient time for heat transfer between the fluid in inner pipe and outer pipe because of low flow rates,leading to large heat loss,i.e.,thermal short-circuiting *** is found that with the inlet flow rate increasing,the heat transfer increases first and then decreases,and the rate of reduction slows down *** the inlet flow rate increases,the pumping power undergoes exponential *** the inlet temperature increasing,the heat transfer decreases almost ***,when the soil temperature at the top of the casing is lower than that of the fluid in the casing,heat is transferred from the fluid in the casing to the soil,and the heat loss increases with the increase of the inlet fluid *** material of inner pipe with high heat conductivity would result in large heat loss under the influence of thermal *** heat load increases while the pumping power required decreases with the increasing of outer pipe *** study is very beneficial for the coaxial shallow borehole exchanger designs and energy conservation of buildings.

关键词： Coaxial borehole heat exchanger Geothermal heat transfer performance CFD

Analysis of the heat transfer performance of Vapor-Condenser during Vacuum Cooling

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Analysis of the Heat Transfer Performance of Vapor-Condenser...

Implementation of heat exchanger performance testing system of heat transfer and flow resistance

第四届国际计算机与计算技术在农业中的应用研讨会

作者： Gailian.Li Tingxiang Jin Chunxia Hu School of Mechanical ＆ Electricity engineering Zhengzhou University of Light Industry

The heat transfer performance of vapor-condenser has been studied under different temperature of cold trap and different thickness of the frost layer in this *** relationship between dimensionless number Nu and Kn is *** results show that the capturing efficiency of cold trap increases with the decrease of the surface temperature of *** frost accumulated on the surface of vapor-condenser can cause the overall heat transfer coefficient decrease,which has a negative effect on heat transfer of *** has an effect on the heat transfer of vapor-condenser during vacuum cooling.

关键词： heat transfer performance Vapor-condenser Cold trap Vacuum cooling

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Journal of Southeast University(English Edition) 2012年第1期28卷 46-51页

作者：操瑞兵陈亚平吴嘉峰董聪盛艳军东南大学能源与环境学院南京210096 东南大学能源热转换及其过程测控教育部重点实验室南京210096

A heat transfer performance testing system is presented with its hardware structure, operation principle, and software control and measurement system. Working fluids of the subsystem include thermal conducting oil, compressed air, glycol water solution and water as the heating fluids, and air and water as the cooling fluids. The heat transfer performance testing of heat exchangers can be conducted not only for a conventional one heating fluid to one cooling fluid, but also for a compound air cooling heat exchanger with two or three heating fluids in parallel or in series. The control and measurement system is implemented based on a LabVIEW software platform, consisting of the data acquisition and process system, and the automotive operation and control system. By using advanced measuring instruments combined with sound computer software control, the testing system has characteristics of a compact structure, high accuracy, a wide range of testing scope and a friendly operation interface. The uncertainty of the total heat transfer coefficient K is less than 5%. The testing system provides a reliable performance testing platform for designing and developing new heat exchangers.

关键词： heat exchanger heat transfer performance testing system LabVIEW

Numerical simulation of flow and heat transfer of n-decane in sub-millimeter spiral tube at supercritical pressure

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Chinese Journal of Chemical Engineering 2023年第8期60卷 173-185页

作者： Jiahao Xing Huaizhi Han Ruitian Yu Wen Luo School of Chemical Engineering Sichuan UniversityChengdu 610065China Engineering Research Center of Combustion and Cooling for Aerospace Power Ministry of EducationSichuan UniversityChengdu 610065China

The flow and heat transfer characteristics of n-decane in the sub-millimeter spiral tube(SMST) at supercritical pressure(p = 3 MPa) are studied by the RNG k-ε numerical model in this paper. The effects of various Reynolds numbers(Re) and structural parameters pitch(s) and spiral diameter(D) are *** indicate that the average Nusselt numberNu and friction factorNu increase with an increase in Re, and decrease with an increase in D/d(tube diameter). In terms of the structural parameter s/d, it is found that as s/d increases, the Nu first increase, and then decrease. and the critical structural parameter is s/d = 4. Compared with the straight tube, the SMST can improve Nu by 34.8% at best, while it can improve Nu by 102.1% at most. In addition, a comprehensive heat transfer coefficient is applied to analyze the thermodynamic properties of SMST. With the optimal structural parameters of D/d = 6 and s/d = 4, the comprehensive heat transfer factor of supercritical pressure hydrocarbon fuel in the SMST can reach 1.074. At last, correlations of the average Nusselt number and friction factor are developed to predict the flow and heat transfer of n-decane at supercritical pressure.

关键词： Sub-millimeter spiral tube Supercritical pressure Numerical simulation heat transfer performance

Recent Advances in Closed Loop Spray Cooling and its Application in Airborne Systems

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Journal of Thermal Science 2021年第1期30卷 32-50页

作者： XU Xinjie WANG Yu JIANG Yanlong LIU Jinxiang YUAN Xiaolei College of Urban Construction Nanjing Tech UniversityNanjing 210009China College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In recent years,the problem of heat dissipation in airborne directed energy weapons has attracted considerable research *** cooling can be applied to cool airborne directed energy weapons,owing to its several advantages such as a large heat transfer coefficient,absence of boiling hysteresis and uniform surface *** examine the potential of an airborne spray cooling system,the typical high heat flux dissipation methods were compared,and the state of the art research on spray cooling was *** review was focused on studies related to the spray cooling hydrodynamic mechanism,experimental studies of closed loop spray cooling,numerical simulation studies about spray cooling and the identification of the factors influencing spray cooling systems,and investigations related to the multiple nozzle spray cooling technology and heat transfer correlation ***,there is a need for further research to investigate the failure phenomenon after the critical state,matching operation of the total system and microscopic characteristics of airborne specific parameters.

关键词： spray cooling closed loop heat transfer performance influencing factor correlations