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Numerical Investigation of Jet Impingement Cooling with Supercritical Pressure Carbon Dioxide in a Multi-Layer Cold Plate during high heat flux

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Journal of Thermal Science 2023年第1期32卷 237-253页

作者： WEN Yaming LI Yulong LI Jingqi YU Xin-Gang National Key Laboratory of Science and Technology on Aero Engines Aero-Thermodynamics&Collaborative Innovation Center for Advanced Aero-Engine School of Energy and Power EngineeringBeihang UniversityBeijing 100191China Beijing Institute of Spacecraft System Engineering Beijing 100094China

Jet impingement cooling with supercritical pressure carbon dioxide in a multi-layer cold plate during the heat flux of 400 W/cm_(2) is investigated numerically.The generation and distribution of pseudocritical fluid with the high specific heat of supercritical pressure carbon dioxide and the mechanism of the heat transfer enhancement led by the high specific heat are analyzed.For a given nozzle diameter,the effects of the geometric parameters of a multi-layer cold plate such as the relative nozzle-to-plate distance,relative plate thickness,and relative upper fluid thickness on the average heat transfer coefficient are studied.The results show that the target surface is cooled effectively with supercritical pressure carbon dioxide jet impingement cooling.When the radial distance is less than 6 mm,the maximum wall temperature is 368 K,which is 30 K lower than the maximum junction temperature for a silicon-based insulated gate bipolar transistor,a typical electronic power device.There is a pseudocritical fluid layer near the target surface,where specific heat reaches above 34 kJ/(kg·K)locally.The drastic rise of the specific heat leads to obvious heat transfer enhancement.Within a certain range,the local heat transfer coefficient and the specific heat are linearly correlated and Stanton number remains constant over this range.The heat transfer coefficient is at a maximum when the relative nozzle-to-plate distance is 1.As the relative plate thickness increases from 0.5 to 3.5 or the relative upper fluid thickness increases from 0.5 to 2.5,the average heat transfer coefficient decreases monotonically.

关键词： high heat flux jet impingement cooling supercritical pressure carbon dioxide heat transfer enhancement

Influence of recrystallization on tungsten divertor monoblock under high heat flux

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Tungsten 2022年第3期4卷 194-202页

作者： Yu-Zhong Jin Xiang Liu You-Yun Lian Jiu-Peng Song Southwestern Institute of Physics Chengdu610225China Xiamen Tungsten Co.Ltd Xiamen361021China

Extremely high heat flux reaching 20 MW·m^(−2) can be foreseen for the future fusion reactor.Such high heat flux would induce recrystallization of tungsten(W)material,leading to significant strength loss of tungsten material and increment of ductility at high temperature,in particular when the temperature is much higher than its ductile-to-brittle transition temperature(DBTT).In this paper,an International Thermonuclear Experimental Reactor(ITER)-like tungsten divertor monoblock is modeled,and benchmark has been done first to get consistent results with ITER.Then,the monoblock structure has been optimized in order to get a lowest possible temperature and stress during heating and cooling phase separately compared to the baseline structure.Structural analysis of two kinds of states:stress-relieved tungsten and recrystallized tungsten using finite element method has been performed,aiming at finding out the recrystallization impact on the mechanical behavior of tungsten in divertor monoblock under cyclic high heat flux.Damages due to progressive deformation and time-independent fatigue lifetime of these two states of tungsten have been assessed and compared according to criteria The Structural Design Criteria for ITER In-vessel Components.Finally,the impact of different material recrystallization temperature on mechanical behavior has been explored under stationary heat load.The result shows that after recrystallization,thermal stress of tungsten material can be released by the larger plastic deformation compared to the stress-relieved tungsten.However,it is easier for recrystallized tungsten to get damaged due to progressive deformation as well as fatigue under 20 MW·m^(−2) cyclic heat flux than stress-relieved tungsten because of its relatively lower yield strength and larger plastic strain,which would cause low-cycle strain fatigue.Furthermore,tungsten with lower recrystallization temperature distorts more seriously,and therefore,it can be predicted the cracks would be initiated more easily.

关键词： Tungsten Finite element method Divertor high heat flux Thermal stress

heat Transfer Characteristics of a Microchannel heat Sink with highly-Dense Micro-Jet Arrays

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Journal of Thermal Science 2024年第3期33卷 1148-1160页

作者： ZHANG Yu CHEN Xiaoyan MIAO Lin CHEN Liang HOU Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Beijing Aerospace Technology Institute Beijing100083China

This paper proposed a new structure of highly-dense micro-jet arrays for hybrid jet-impingement/microchannel heat sinks(~120 jet per cm^(2) with jet width of 0.35 mm).Parametric study is performed to investigate the influence of structure and flow parameters on the convective heat transfer of water jet cooling in confined space.The simulation results show that the optimal jet width,jet spacing and impingement distance are around 0.2 mm,0.2 mm and 0.3 mm,respectively,which can achieve a low thermal resistance as well as a relatively low pressure drop.The analysis of the heat transfer pathways shows that the micro-fin jet structures can extend the impinging heat transfer area and conduct a considerable proportion of heat,which can reach up to 38.9%with the Reynolds number ranging from 797.1 to 5602.2.The heat transfer characteristics in the heat sink will shift from impingement dominated heat transfer to the channel-convection dominated heat transfer as the jet impingement distance increases.A correlation is proposed to predict the average Nusselt number on the stagnation area for the heat sink with different structure parameters,and the deviations of predictions from the numerical results are less than 10%.

关键词： hybrid heat sink impingement microchannel thermal management high heat flux

Critical heat flux(CHF)Correlations for Subcooled Water Flow Boiling at high Pressure and high heat flux

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Journal of Thermal Science 2021年第1期30卷 279-293页

作者： LIU Ping GUO Yusheng DING Wenlong TANG Mingyun SONG Yuntao PENG Xuebing JI Jiadong CHEN Qinghua MAO Xin State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China School of Mechanical Engineering Anhui University of Science and TechnologyHuainan 232001China Anhui Key Laboratory of Mine Intelligent Equipment and Technology Anhui University of Science and TechnologyHuainan 232001China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China School of Mining and Safety Engineering Anhui University of Science and TechnologyHuainan 232001China

The subcooled water flow boiling is beneficial for removing the high heat flux from the divertor in the fusion reactor,for which an accurate critical heat flux(CHF)correlation is necessary.Up to now,there are many CHF correlations mentioned for subcooled water flow boiling in the open literatures.However,the CHF correlations’accuracies for the prediction of subcooled water flow boiling are not satisfactory at high heat flux and high pressure for reactor divertor.The present paper compiled 1356 CHF experimental data points from 15 independent open literatures and evaluated 10 existing CHF correlations in subcooled water flow boiling.From the evaluation,the W-2 CHF correlation performs best for the experimental CHF data in all existing critical heat flux correlations.However,the predicted mean absolute error(MAE)of the W-2 correlation is not very ideal for all database and the MAE of the W-2 correlation is from 30%to 50%for some database.In order to enhance the CHF prediction accuracy in subcooled water flow boiling at high heat flux and high pressure,the present paper developed a new CHF correlation.Compared with other existing CHF correlations,the new CHF correlation greatly enhances the prediction accuracy over a broad range of pressures and heat fluxes which are desired in the cooling of high heat flux devices,such as those in the fusion reactor divertor.The validation results show that the new correlation has a MAE of 10.05%and a root mean squared error(RMSE)of 16.61%,predicting 68.1%of the entire database within±10%and 81.5%within±15%.The MAE of the new CHF correlation is 7.4%less than that of the best existing one(W-2 correlation),further confirming its superior prediction accuracy and reliability.Besides,the new CHF correlation works well not only for a uniform power profile but also for a non-uniform power profile in subcooled water flow boiling at high pressure and high heat flux.

关键词： reactor divertor correlations subcooled water flow boiling critical heat flux(CHF) high heat flux high pressure

Behavior of Brazed W/Cu Mockup Under high heat flux Loads

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Plasma Science and Technology 2014年第3期16卷 278-282页

作者：陈蕾练友运刘翔 Southwestern Institute of Physics

In order to transfer the heat from the armor to the coolant, tungsten has to be connected with a copper heat sink. The joint technology is the most critical issue for manufacturing plasma facing components. Consequently, the reliability of the joints should be verified by a great number of high-heat-flux （HHF） tests to simulate the real load conditions. W/Cu brazed joint technology with sliver free filler metal CuMnNi has been developed at Southwestern Institute of Physics （SWIP）. Screening and thermal fatigue tests of one small-scale fiat tile W/CuCrZr mockup were performed on a 60 kW electron-beam Material testing scenario （EMS-60） constructed recently at SWIP. The module successfully survived screening test with the absorbed power density （Pabs） of 2 MW/m2 to 10 MW/m2 and the following 1000 cycles at Pabs of 7.2 MW/m2 without hot spots and overheating zones during the whole test campaign. Metallurgy and SEM observations did not find any cracks at both sides and the interface, indicating a good bonding of W and CuCrZr alloy. In addition, finite element simulations by ANSYS 12.0 under experimental load conditions were performed and compared with experimental results.

关键词： brazing high heat flux finite element modeling

Flow Boiling of Ammonia in a Diamond-Made MicroChannel heat Sink for high heat flux Hotspots

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Journal of Thermal Science 2020年第5期29卷 1333-1344页

作者： YANG Qi MIAO Jianyin ZHAO Jingquan HUANG Yanpei FU Weichun SHEN Xiaobin School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory of Space Thermal Control Technology Beijing Institute of Spacecraft System EngineeringChina Academy of Space TechnologyBeijing 100094China

To solve the heat dissipation problem of electronic devices with high heat flux hotspots,a diamond microchannel heat sink consisting of 37 parallel triangular microchannels with channel lengths of 45 mm and hydraulic diameters of 280|im was designed.The flow boiling heat transfer characteristics of ammonia in the microchannels were investigated under high heat fluxes of 473.9-1000.4 W/cm^2.Saturated flow boiling experiments with saturation temperatures of 25℃,30℃,and 35℃ and mass fluxes of 98-1200 kg/m^2s were conducted,as well as subcooled flow boiling with inlet subcooling of 5℃ as a comparison.The temperature and pressure drop measurements were analyzed.The main conclusions below can be drawn.(1)At a given heat flux,the heat source temperature first decreased and then increased with the mass flux,and there existed an optimum mass flux to optimize the cooling performance of the heat sink.(2)The heat transfer performance under the saturated inlet condition was obviously better than that under the subcooled inlet condition.(3)A larger saturation temperature leaded to weakening of both the heat transfer capacity and the stability of the microchannel heat sink.Notably,with the high heat diffusion ability of the diamond substrate and the great heat transfer capacity of ammonia flow boiling in microchannels,the heat sink can achieve a heat removal capacity of up to 1000.4 W/cm^2.

关键词： high heat flux flow boiling microchannel ammonia multipoint heat sources

An investigation on application potentiality of microstructure heat sinks with different flow topological morphology

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Science China(Technological Sciences) 2022年第12期65卷 2895-2909页

作者： YAO XiaoLe SHI QianLei LIU Qian QIN Le JU Xing XU Chao Key Laboratory of Power Station Energy Transfer Conversion and System of MOE North China Electric Power UniversityBeijing 102206China

Microstructure heat sinks have great potential for high heat flux cooling.In this paper,we compared microchannel(MC),micro-pin-fin(MPF),manifold microchannel(MMC),and manifold micro-pin-fin(MMPF)heat sinks to figure out the pros and cons.Fluid flow and manifold unit models are used to study thermal and hydrodynamic performance.The heat sinks with different channel/fin sizes,manifold numbers,and porosities are discussed according to the pressure drop,temperature,thermal resistance,and coefficient of performance.Results show that MMC and MMPF heat sinks are superior to MC and MPF heat sinks,and there are also differences between MMC and MMPF heat sinks.Typically,the MMPF heat sink has lower maximum temperature,temperature non-uniformity,and total thermal resistance R_(tot).In contrast,the MMC heat sink has a lower pressure drop and higher COP.For the MMPF heat sink,at the nozzle width of 6.75μm and the MPF width of 70.71μm(porosity=0.167),it achieves the lowest total thermal resistance of R_(tot)=2.97×10^(-6)K m^(2)/W.Under 10^(3)W/cm^(2)heat flux,the maximum surface temperature rise is 29.74 K,and the maximum temperature difference of the heating surface is 3.15 K.This research initially provides a clear reference on the selection of single-phase cooling microstructures for ultra-high heat flux dissipation.

关键词： heat sink topology manifold microchannel micro-pin-fin high heat flux

Ground experimental investigations into an ejected spray cooling system for space closed-loop application

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Chinese Journal of Aeronautics 2016年第3期29卷 630-638页

作者： Zhang Hongsheng Li Yunze Wang Shengnan Liu Yang Zhong Mingliang School of Aeronautic Science and Engineering Beihang University School of Automation Science and Electrical Engineering Beihang University

Spray cooling has proved its superior heat transfer performance in removing high heat flux for ground applications. However, the dissipation of vapor liquid mixture from the heat sur- face and the closed-loop circulation of the coolant are two challenges in reduced or zero gravity space enviromnents. In this paper, an ejected spray cooling system for space closed-loop application was proposed and the negative pressure in the ejected condenser chamber was applied to sucking the two-phase mixture from the spray chamber. Its ground experimental setup was built and exper- imental investigations on the smooth circle heat surface with a diameter of 5 mm were conducted with distilled water as the coolant spraying from a nozzle of 0.51 mm orifice diameter at the inlet temperatures of 69.2 ℃ and 78.2 ℃ under the conditions of heat flux ranging from 69.76 W/cm2 to 311.45 W/cm2, volume flow through the spray nozzle varying from 11,22 L：h to 15.76 L·h. Work performance of the spray nozzle and heat transfer performance of the spray cooling system were analyzed; results show that this ejected spray cooling system has a good heat transfer performance and provides valid foundation for space closed-loop application in the near future.

关键词： Ejected spray cooling systemEvaluation models Ground experiment heat transfer performance high heat flux Space closed-loop

Thermal Shock Behavior Analysis of Tungsten-Armored Plasma-Facing Components for Future Fusion Reactor

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Acta Metallurgica Sinica(English Letters) 2018年第5期31卷 515-522页

作者： Shu-Ming Wang Jiang-Shan Li Yan-Xin Wang Xiao-Fang Zhang Qing Ye Department of Materials Science and Engineering University of Science and Technology Beijing

In a fusion reactor, plasma-facing components（PFCs） will suffer severe thermal shock; behavior and performance of PFCs under high heat flux（HHF） loads are of major importance for the long-term stable operation of the reactor. This work investigates the thermo-mechanical behaviors of tungsten armor under high heat loads by the method of finite element modeling and simulating. The temperature distribution and corresponding thermal stress changing rule under different HHF are analyzed and deduced. The Manson–Coffin equation is employed to evaluate the fatigue lifetime（cyclic times of HHF loading） of W-armored first wall under cyclic HHF load. The results are useful for the formulation design and structural optimization of tungsten-armored PFCs for the future demonstration fusion reactor and China fusion experimental thermal reactor.

关键词： Plasma-facing components Thermo-mechanical behavior high heat flux Tungsten armor-Fatigue lifetime Finite element method