Flow boiling heat transfer enhancement of refrigerant mixtures in micro-tubes
1.School of Energy and Power Engineering,Jiangsu University,Zhenjiang,Jiangsu 212013,China;2.School of Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China
Abstract：Experimental study was carried out to investigate forced flow boiling enhanced heat transfer in horizontal micro-tube（d=0.86 mm）,mini-tube（d=1.92 mm） and small-tube（d=3.60 mm） of 200 mm heated length with non-azeotropic refrigerant mixtures of R32 and R134a（25%/75%,mass ratio）,respectively.By comparing flow boiling heat transfer coefficient with mini-tube and small-tube,the heat transfer enhancement coefficient（Ec） in micro-tube was defined,so were the Ecm and Ecs for mini-tube and small-tube.The variations of Ecm and Ecs under different working conditions were analyzed according to flow boiling heat transfer mechanisms in different enhanced tube.The results show that Ecm and Ecs vary from 1.01 to 2.33 and from 1.03 to 3.54 respectively.In most working conditions both the value of Ecm and its variation are small,while the Ecs is the opposite.At high heat flux and high mass quality level the values of Ecm and Ecs are large.The flow boiling heat transfer enhancement effect of micro-tube is influenced strongly by heat transfer mechanisms and its transition region in different enhanced tube.Ecm and Ecs are much higher when nucleation boiling mechanisms dominate at high heat flux level and when deterioration of heat transfer begins at high mass quality level in micro-tube.
胡自成, 马虎根, 王谦. 微圆管内非共沸混合工质流动沸腾传热强化[J]. 江苏大学学报（自然科学版）, 2009, 30(2): 160-164.
Hu Zicheng, Ma Hugen, Wang Qian. Flow boiling heat transfer enhancement of refrigerant mixtures in micro-tubes[J]. Journal of Jiangsu University(Natural Science Eidtion)
, 2009, 30(2): 160-164.
2009, Vol. 30 
