复杂微通道内对流传热的场协同及熵产
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摘要
利用场协同和熵产原理研究了针肋宽度、凹穴宽度及雷诺数(Re)对凹穴和针肋组合式微通道内对流传热特性的影响,分析了微结构强化传热的本质原因,并对微通道的综合性能进行了评价。结果表明,增大针肋和凹穴宽度能够显著减小传热协同角,提高流场和温度场的协同程度,有利于强化对流传热,但局部漩涡会使流动协同角减小,增大微通道压降;增大针肋宽度能够提高能量利用效率,从而强化传热,但同时导致流动熵产率增大;适当增大凹穴宽度能够减小传热熵产率,但凹穴宽度过大会导致传热不可逆性和流动摩擦均增大;综合考虑泵功、相对针肋宽度和相对凹穴宽度,提出了预测热阻的经验关联式;当相对针肋宽度为0.2,相对凹穴宽度为2时,微通道的热阻最小,综合性能最好。
The effects of fin width,cavity width and Reynolds number(Re)on the convective heat transfer characteristics in the microchannels with cavities and fins were studied by field synergy and entropy generation principle.The heat transfer enhancement mechanism of micro structures was analyzed,and the comprehensive performance of the microchannel was assessed.The results showed that the increase of fin width and cavity width was able to reduce the heat transfer synergy angle,improve the synergy relationship between flow field and temperature field obviously and enhance the convective heat transfer.However,the local vortexes caused the decrease of flow synergy angle and increased the pressure drop of the microchannels;the increase of fin width was helpful to improve the energy utilization efficiency and enhance heat transfer associated with the increase of the entropy generation rate of fluid friction;increasing the cavity width properly was able to reduce the entropy generation rate of heat transfer,but the extremely large cavity width led to the increase of the heat transfer irreversibility and flow friction;considering the pump power,relative fin width and relative cavity width,new correlation of the thermal resistance was proposed;the microchannel heat sink with relative fin width 0.2 and relative cavity width 2 yielded the lowest thermal resistance and the best overall performance.
The effects of fin width,cavity width and Reynolds number(Re)on the convective heat transfer characteristics in the microchannels with cavities and fins were studied by field synergy and entropy generation principle.The heat transfer enhancement mechanism of micro structures was analyzed,and the comprehensive performance of the microchannel was assessed.The results showed that the increase of fin width and cavity width was able to reduce the heat transfer synergy angle,improve the synergy relationship between flow field and temperature field obviously and enhance the convective heat transfer.However,the local vortexes caused the decrease of flow synergy angle and increased the pressure drop of the microchannels;the increase of fin width was helpful to improve the energy utilization efficiency and enhance heat transfer associated with the increase of the entropy generation rate of fluid friction;increasing the cavity width properly was able to reduce the entropy generation rate of heat transfer,but the extremely large cavity width led to the increase of the heat transfer irreversibility and flow friction;considering the pump power,relative fin width and relative cavity width,new correlation of the thermal resistance was proposed;the microchannel heat sink with relative fin width 0.2 and relative cavity width 2 yielded the lowest thermal resistance and the best overall performance.
引文
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[25]CHAI Lei,XIA Guodong,WANG Liang,et al.Heat transfer enhancement in microchannel heat sinks with periodic expansion-constriction cross-sections[J].International Journal of Heat and Mass Transfer,2013,62:741-751.
[2]GHANI I A,SIDIK N A C,KAMARUZAMAN N.Hydrothermal performance of microchannel heat sink:the effect of channel design[J].International Journal of Heat and Mass Transfer,2017,107:21-44.
[3]CHIAM Z L,LEE P S,SINGH P K,et al.Investigation of fluid flow and heat transfer in wavy micro-channels with alternating secondary branches[J].International Journal of Heat and Mass Transfer,2016,101:1316-1330.
[4]ZHAI Yuling,LI Zhouhang,WANG Hua,et al.Thermodynamic analysis of the effect of channel geometry on heat transfer in double-layered microchannel heat sinks[J].Energy Conversion and Management,2017,143:431-439.
[5]马丹丹,夏国栋,陈卓,等.两层堆叠3D-IC层间液体冷却流动及换热特性[J].航空动力学报,2017,32(7):1569-1576.MA Dandan,XIA Guodong,CHEN Zhuo,et al.Flow and heat transfer characteristics of interlayer liquid cooling for3D-IC with two stacked layers[J].Journal of Aerospace Power,2017,32(7):1569-1576.(in Chinese)
[6]DEHGHAN M,DANESHIPOUR M,VALIPOUR M S,et al.Enhancing heat transfer in microchannel heat sinks using converging flow passages[J].Energy Conversion and Management,2015,92:244-250.
[7]CHANDRA A K,KISHOR K,MISHRA P K,et al.Numerical simulation of heat transfer enhancement in periodic converging-diverging microchannel[J].Procedia Engineering,2015,127:95-101.
[8]KHOSHVAGHT-ALIABADI M.Influence of different design parameters and Al2O3-water nanofluid flow on heat transfer and flow characteristics of sinusoidal-corrugated channels[J].Energy Conversion and Management,2014,88:96-105.
[9]XU Minghai,LU Hui,GONG Liang,et al.Parametric numerical study of the flow and heat transfer in microchannel with dimples[J].International Communications in Heat and Mass Transfer,2016,76:348-357.
[10]GUO Z Y,LI D Y,WANG B X.A novel concept of convective heat transfer enhancement[J].International Journal of Heat and Mass Transfer,1998,41(14):2221-2225.
[11]李志信,过增元.对流传热优化的场协同理论[M].北京:科学出版社,2010.
[12]BI C,TANG G H,TAO W Q.Heat transfer enhancement in mini-channel heat sinks with dimples and cylindrical grooves[J].Applied Thermal Engineering,2013,55(1/2):121-132.
[13]JIN Yu,TANG Guihua,HE Yaling,et al.Parametric study and field synergy principle analysis of H-type finned tube bank with 10rows[J].International Journal of Heat and Mass Transfer,2013,60:241-251.
[14]GUO Jiangfeng,XU Mingtian,CHENG Lin.Second law analysis of curved rectangular channel[J].International Journal of Thermal Sciences,2011,50(5):760-768.
[15]翟玉玲,钟桂健,李舟航.结构形式对双层微通道热沉传热性能的影响[J].航空动力学报,2018,33(3):565-572.ZHAI Yuling,ZHONG Guijian,LI Zhouhang.Effect of structure on heat transfer performance in double layered microchannel heat sinks[J].Journal of Aerospace Power,2018,33(3):565-572.(in Chinese)
[16]HUANG Shanbo,ZHAO Jin,GONG Liang,et al.Thermal performance and structure optimization for slotted microchannel heat sink[J].Applied Thermal Engineering,2017,115:1266-1276.
[17]BEJAN A.Entropy generation through heat and fluid flow[M].New York:Wiley,1982.
[18]CHAI Lei,XIA Guodong,WANG Huasheng.Parametric study on thermal and hydraulic characteristics of laminar flow in microchannel heat sink with fan-shaped ribs on sidewalls:Part 3performance evaluation[J].International Journal of Heat and Mass Transfer,2016,97:1091-1101.
[19]贾玉婷,夏国栋,马丹丹,等.水滴型凹穴微通道流动与传热的熵产分析[J].机械工程学报,2017,53(4):141-148.JIA Yuting,XIA Guodong,MA Dandan,et al.Entropy generation analysis of flow and heat transfer in microchannel with droplet reentrant cavities[J].Journal of Mechanical Engineering,2017,53(4):141-148.(in Chinese)
[20]LI Yifan,XIA Guodong,MA Dandan,et al.Characteristics of laminar flow and heat transfer in microchannel heat sink with triangular cavities and rectangular ribs[J].International Journal of Heat and Mass Transfer,2016,98:17-28.
[21]LI Yifan,XIA Guodong,JIA Yuting,et al.Effect of geometric configuration on the laminar flow and heat transfer in microchannel heat sink with cavities and fins[J].Numerical Heat Transfer:Part A Applications,2017,71(5):528-546.
[22]李艺凡.复杂结构微通道内流体流动及沸腾传热特性研究[D].北京:北京工业大学,2017.LI Yifan.Fluid flow and boiling heat transfer characteristics in microchannels with complex structure[D].Beijing:Beijing University of Technology,2017.(in Chinese)
[23]ROSA P,KARAYIANNIS T G,COLLINS M W.Singlephase heat transfer in microchannels:the importance of scaling effects[J].Applied Thermal Engineering,2009,29(17):3447-3468.
[24]KANDLIKAR S,GARIMELLA S,LI D,et al.Heat transfer and fluid flow in minichannels and microchannels[M].Oxford,UK:Elsevier,2006.
[25]CHAI Lei,XIA Guodong,WANG Liang,et al.Heat transfer enhancement in microchannel heat sinks with periodic expansion-constriction cross-sections[J].International Journal of Heat and Mass Transfer,2013,62:741-751.