多孔细径微肋管内CO_2流动蒸发换热特性的研究  

FLOW BOILING OF SUB-CRITICAL CO_2 IN EXTRUDED MINI-CHANNELS WITH MICRO-FINS

作　　者：吴晓敏[1] 汤英杰[1] 李辉[1] 王维城[1] 

机构地区：[1]清华大学热能工程系热科学与动力工程教育部重点实验室,北京100084

出　　处：《工程热物理学报》2007年第z2期9-12,共4页Journal of Engineering Thermophysics

基　　金：教育部科学技术重大项目资助(No.306001);国家高技术研究发展计划(863计划)项目(No.2006AA05Z416)

摘　　要：对亚临界二氧化碳在带有微肋的微细通道内的蒸发换热特性进行了实验研究.实验段为长0.6 m,内径1.7 mm的八孔带0.16 mm高微肋的铝制扁管。实验中参数的变化为:蒸发温度1～15℃,质量流速100～300 kg/m^2s,热流密度1.67～8.33 kW/m^2,干度0.1～0.9.实验结果表明,二氧化碳在带有微肋的微细通道中的蒸发换热系数高于其在光滑微细通道内的换热。二氧化碳的流动蒸发换热系数主要受热流密度和蒸发温度的影响,基本上是换热系数随热流密度及蒸发温度的增加而增加,但同时临界干度前移及滞后,而质量流速对换热系数的影响较弱;压力损失随质量流速和热流密度的增加以及蒸发温度的降低而增加.The flow boiling characteristics of sub-critical CO_2 in mini-channels with micro-fins was investigated experimentally.Tested was a 0.6 m long multi-port extruded aluminum tube that had 8 flow-channels of 1.7 mm ID with micro-fins of 0.16 mm height.The tube was set in horizontal orientation and heated by direct current.Heat transfer and pressure drop were measured for 100～300 kg/m^2s mass fluxes,1～15℃evaporating temperatures,1.67～8.33 kW/m^2 heat fluxes,and 0.1～0.9 vapor qualities.The test results showed that the heat transfer coefficient of CO_2 in mini-channels with micro-fins was higher than that in smooth mini-channels.Such coefficient was mainly affected by heat flux and evaporating temperature,it increased with increasing the heat flux and the evaporating temperature,but at the same time the dry-out occurred earlier with the former and later with the latter.The mass flux has less effect on the heat transfer coefficient.The pressure drop increased with increasing the mass flux and the heat flux,but decreasing the evaporating temperature.

关 键 词：二氧化碳 流动蒸发 多孔细径微肋管 强化传热 

分 类 号：TK124[动力工程及工程热物理—工程热物理]