R141b在圆形微通道内的沸腾换热实验研究
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摘要
为提高换热强度、解决设备内部高热流密度散热问题,采用实验方法研究R141b在不同直径(D=0.5mm和1.0mm)水平圆形微通道内的沸腾换热特性,分析了热流密度(q=2.0kW/m~2～47.6kW/m~2)、质量干度(x=0～0.6)、质量流速(G=111.11kg/(m~2·s)～333.33kg/(m~2·s))的变化对平均传热系数h的影响,探究不同情况下影响沸腾换热的主导因素。实验研究表明:平均传热系数h随热流密度q的增加而减小,在不同范围内减小速率有明显差异;热流密度q=2kW/m~2～5kW/m~2时质量流速G对平均传热系数h影响较明显,热流密度较高时质量流速G对换热影响很小;在质量流速G=111.11kg/(m~2·s)～333.33kg/(m~2·s),质量干度x>0.3时,平均传热系数h随质量干度x增加而明显下降,在设计微通道换热器时应尽量使R141b处于初始沸腾阶段以获得更好换热效果,并采取一定措施预防干度过高引起的换热恶化。
In order to intensify heat transfer and solve the problem of high heat flux and heat dissipation in-side the equipment,the boiling heat transfer characteristics of R141 b in horizontal micro-channels with differentdiameters(D=0.5 mm and 1.0 mm)were studied experimentally. The effects of heat flux(q=2.0 kW/m~2～47.6 kW/m~2),vapor quality(x=0～0.6)and mass flow rate(G=111.11 kg/(m~2·s)～333.33 kg/(m~2·s))on the average heattransfer coefficient h were analyzed,and the dominant factors affecting boiling heat transfer were explored underdifferent conditions. The experimental study showed that the average heat transfer coefficient h decreased with theincrease of heat flux q in significantly different rate according to different range. The effects of mass flow rate G onthe average heat transfer coefficient h are obvious when heat flux q=2 kW/m~2～5 kW/m~2,while when the heat flux ishigh,the mass flow rate G has little effect on the heat transfer. At different mass flow rate(G=111.11 kg/(m~2·s)～333.33 kg/(m~2·s))when the vapor quality x>0.3,the average heat transfer coefficient h decreased with increas-ing vapor quality x. Micro-channel heat exchangers should be well-designed to insure R141 b working under theinitial boiling stage to achieve better heat exchange effect,and certain measures should be taken to prevent the heat deterioration caused by excessive dryness.
In order to intensify heat transfer and solve the problem of high heat flux and heat dissipation in-side the equipment,the boiling heat transfer characteristics of R141 b in horizontal micro-channels with differentdiameters(D=0.5 mm and 1.0 mm)were studied experimentally. The effects of heat flux(q=2.0 kW/m~2～47.6 kW/m~2),vapor quality(x=0～0.6)and mass flow rate(G=111.11 kg/(m~2·s)～333.33 kg/(m~2·s))on the average heattransfer coefficient h were analyzed,and the dominant factors affecting boiling heat transfer were explored underdifferent conditions. The experimental study showed that the average heat transfer coefficient h decreased with theincrease of heat flux q in significantly different rate according to different range. The effects of mass flow rate G onthe average heat transfer coefficient h are obvious when heat flux q=2 kW/m~2～5 kW/m~2,while when the heat flux ishigh,the mass flow rate G has little effect on the heat transfer. At different mass flow rate(G=111.11 kg/(m~2·s)～333.33 kg/(m~2·s))when the vapor quality x>0.3,the average heat transfer coefficient h decreased with increas-ing vapor quality x. Micro-channel heat exchangers should be well-designed to insure R141 b working under theinitial boiling stage to achieve better heat exchange effect,and certain measures should be taken to prevent the heat deterioration caused by excessive dryness.
引文
[1]孙彦红.微液膜对微通道流动沸腾影响机理的研究[D].北京:中国科学院工程热物理研究所,2017.
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[5] Issam Mudawar. Two-Phase Micro-Channel Heat Sinks:Theory, Applications and Limitations[J]. Journal of Electronic Packaging,2011,133(4).
[6] Mehendale S S. Fluid Flow and Heat Transfer at Micro and Meso-Scales with Application to Heat Exchanger Design[J]. Applied Mechanics Reviews,2000,53(7):175-193.
[7] Ong C L. Macro-to-Microchannel Transition in TwoPhase Flow,Part 1:Two-Phase Flow Patterns and Film Thickness Measurements[J]. Experimental Thermal and Fluid Science,2011,35(1):37-47.
[8] Bao Z Y. Flow Boiling Heat Transfer of Freon R1 1 and HCFC1 23 in Narrow Passages[J]. International Journal of Heat and Mass Transfer,2000,43(18):3347-3358.
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[10] Cheng Ping. Recent Work on Boiling and Condensation in Microchannels[J]. Journal of Heat Transfer,2009,131(4):569-574.
[11] Saitoh Shizuo. Effect of Tube Diameter on Boiling Heat Transfer of R-134 a in Horizontal Small-Diameter Tubes[J]. International Journal of Heat and Mass Transfer,2005,48(23):4973-4984.
[12] Chin L Ong, Thome. Flow Boiling Heat Transfer of R134a,R236fa and R245fa in a Horizontal 1.030mm Circular Channel[J]. Experimental Thermal and Fluid Science,2009,33(4):651-663.
[13]李琳,刘存良,杨祺,等.微细管道内R141b沸腾气液两相流动与换热特性数值仿真[J].推进技术,2018,39(4):802-809.(LI Lin,LIU Cun-liang,YANG Qi,et al. Numerical Simulations on Two-Phase Boiling Flow and Heat Transfer of Refrigerant R141b in Micro/Mini-Channel[J]. Journal of Propulsion Technology,2018,39(4):802-809.)
[14] Han J L,Sang Y L. Heat Transfer Correlation for Boiling Flows in Small Rectangular Horizontal Channels with Low Aspect Tatios[J]. International Journal of Multiphase Flow,2001,27(12):2043-2062.
[15] Steinke Mark E,Kandlikar. An Experimental Investigation of Flow Boiling Characteristics of Water in Parallel Microchannels[J]. Journal of Heat Transfer,2004,126(4):518-526.
[16]姜玉廷,郑群,罗铭聪,等.叶片前缘两相流冲击冷却的耦合数值模拟[J].推进技术,2015,36(3):443-449.(JIANG Yu-ting,ZHENG Qun,LUO Mingcong,et al. Conjugate Simulation of Two Phase Flow Impingement Cooling[J]. Journal of Propulsion Technology,2015,36(3):443-449.)
[17]谷云庆,牟介刚,代东顺,等.基于气体射流的气液两相流动减阻特性[J].推进技术,2015,36(11):1640-1647.(GU Yun-qing,MU Jie-gang,DAI Dongshi,et al. Drag Reduction Characteristics on Gas-Liquid Two-Phase Flow Based on Gas Jet[J]. Journal of Propulsion Technology,2015,36(11):1640-1647.)
[18]张宗卫,郑东生,张盛辉,等. R141b在矩形微尺度通道中的两相流传热特性[J].航空动力学报,2018,33(8):1793-1800.
[19]付鑫,张鹏,包乾,等.微通道热沉内液氮流动沸腾的换热特性[J].工程热物理学报,2011,32(5):811-815.
[20]胡丽琴,罗小平,廖寿学.矩形微细通道纳米流体沸腾流动阻力特性研究[J].中南大学学报(自然科学版),2014,45(7):2209-2216.
[21] Yang Q,Shu B,Wang J,et al. Experimental Investigation on Flow Boiling Heat Transfer and Flow Patterns in a Single Micro-Channel with Large Mass Velocity[J]. Experimental Thermal and Fluid Science,2018,91:283-291.
[22] Maxime Ducoulombier. Carbon Dioxide Flow Boiling in a Single Microchannel,Part II:Heat Transfer[J]. Experimental Thermal and Fluid Science, 2011, 35(4):597-611.
[23] Kline S,Mcclintock F A. Describing Uncertainties in Single-Sample Experiments[J]. Mechanical Engineering,1953,75(1):3-8.
[24] Li X,Jia L,Dang C,et al. Visualization of R134a Flow Boiling in Micro-Channels to Establish a Novel BubblySlug Flow Transition Criterion[J]. Experimental Thermal and Fluid Science,2018,91:230-244.
[25] Charnay Romain. Flow Boiling Heat Transfer in Minichannels at High Saturation Temperatures,Part I:Experimental Investigation and Analysis of the Heat Transfer Mechanisms[J]. International Journal of Heat and Mass Transfer,2015,87(2):636-652.
[2] Bachmann C,Bar-Cohen A. Hotspot Remediation with Anisotropic Thermal Interface Materials[C]. Orlando:Intersociety Conference on IEEE,2008:238-247.
[3] Singh B S,Hasan M M. Innovative Multi-Environment,Multimode Thermal Control System[C]. Dubrovnik:International Conference on Environmental Systems,2007.
[4] Charnay Romain. Flow Boiling Heat Transfer in Minichannels at High Saturation Temperatures,Part I:Experimental Investigation and Analysis of the Heat Transfer Mechanisms[J]. International Journal of Heat and Mass Transfer,2015,87(2):636-652.
[5] Issam Mudawar. Two-Phase Micro-Channel Heat Sinks:Theory, Applications and Limitations[J]. Journal of Electronic Packaging,2011,133(4).
[6] Mehendale S S. Fluid Flow and Heat Transfer at Micro and Meso-Scales with Application to Heat Exchanger Design[J]. Applied Mechanics Reviews,2000,53(7):175-193.
[7] Ong C L. Macro-to-Microchannel Transition in TwoPhase Flow,Part 1:Two-Phase Flow Patterns and Film Thickness Measurements[J]. Experimental Thermal and Fluid Science,2011,35(1):37-47.
[8] Bao Z Y. Flow Boiling Heat Transfer of Freon R1 1 and HCFC1 23 in Narrow Passages[J]. International Journal of Heat and Mass Transfer,2000,43(18):3347-3358.
[9] Lee Jaeseon,Mudawar. Two Phase Flow in High-HeatFlux Micro-Channel Heat Sink for Refrigeration Cooling Applications,Part 1:Pressure Drop Characteristics[J].International Journal of Heat and Mass Transfer,2005,48(5):928-940.
[10] Cheng Ping. Recent Work on Boiling and Condensation in Microchannels[J]. Journal of Heat Transfer,2009,131(4):569-574.
[11] Saitoh Shizuo. Effect of Tube Diameter on Boiling Heat Transfer of R-134 a in Horizontal Small-Diameter Tubes[J]. International Journal of Heat and Mass Transfer,2005,48(23):4973-4984.
[12] Chin L Ong, Thome. Flow Boiling Heat Transfer of R134a,R236fa and R245fa in a Horizontal 1.030mm Circular Channel[J]. Experimental Thermal and Fluid Science,2009,33(4):651-663.
[13]李琳,刘存良,杨祺,等.微细管道内R141b沸腾气液两相流动与换热特性数值仿真[J].推进技术,2018,39(4):802-809.(LI Lin,LIU Cun-liang,YANG Qi,et al. Numerical Simulations on Two-Phase Boiling Flow and Heat Transfer of Refrigerant R141b in Micro/Mini-Channel[J]. Journal of Propulsion Technology,2018,39(4):802-809.)
[14] Han J L,Sang Y L. Heat Transfer Correlation for Boiling Flows in Small Rectangular Horizontal Channels with Low Aspect Tatios[J]. International Journal of Multiphase Flow,2001,27(12):2043-2062.
[15] Steinke Mark E,Kandlikar. An Experimental Investigation of Flow Boiling Characteristics of Water in Parallel Microchannels[J]. Journal of Heat Transfer,2004,126(4):518-526.
[16]姜玉廷,郑群,罗铭聪,等.叶片前缘两相流冲击冷却的耦合数值模拟[J].推进技术,2015,36(3):443-449.(JIANG Yu-ting,ZHENG Qun,LUO Mingcong,et al. Conjugate Simulation of Two Phase Flow Impingement Cooling[J]. Journal of Propulsion Technology,2015,36(3):443-449.)
[17]谷云庆,牟介刚,代东顺,等.基于气体射流的气液两相流动减阻特性[J].推进技术,2015,36(11):1640-1647.(GU Yun-qing,MU Jie-gang,DAI Dongshi,et al. Drag Reduction Characteristics on Gas-Liquid Two-Phase Flow Based on Gas Jet[J]. Journal of Propulsion Technology,2015,36(11):1640-1647.)
[18]张宗卫,郑东生,张盛辉,等. R141b在矩形微尺度通道中的两相流传热特性[J].航空动力学报,2018,33(8):1793-1800.
[19]付鑫,张鹏,包乾,等.微通道热沉内液氮流动沸腾的换热特性[J].工程热物理学报,2011,32(5):811-815.
[20]胡丽琴,罗小平,廖寿学.矩形微细通道纳米流体沸腾流动阻力特性研究[J].中南大学学报(自然科学版),2014,45(7):2209-2216.
[21] Yang Q,Shu B,Wang J,et al. Experimental Investigation on Flow Boiling Heat Transfer and Flow Patterns in a Single Micro-Channel with Large Mass Velocity[J]. Experimental Thermal and Fluid Science,2018,91:283-291.
[22] Maxime Ducoulombier. Carbon Dioxide Flow Boiling in a Single Microchannel,Part II:Heat Transfer[J]. Experimental Thermal and Fluid Science, 2011, 35(4):597-611.
[23] Kline S,Mcclintock F A. Describing Uncertainties in Single-Sample Experiments[J]. Mechanical Engineering,1953,75(1):3-8.
[24] Li X,Jia L,Dang C,et al. Visualization of R134a Flow Boiling in Micro-Channels to Establish a Novel BubblySlug Flow Transition Criterion[J]. Experimental Thermal and Fluid Science,2018,91:230-244.
[25] Charnay Romain. Flow Boiling Heat Transfer in Minichannels at High Saturation Temperatures,Part I:Experimental Investigation and Analysis of the Heat Transfer Mechanisms[J]. International Journal of Heat and Mass Transfer,2015,87(2):636-652.