微通道内流动沸腾换热特性实验研究

Experimental investigation on flow boiling heat transfer in a micro-tube

采用实验方法对制冷剂R134a在内径为1.98mm的水平光滑铜管内的流动沸腾换热特性进行研究。试验中,质量流速范围720~900kg/(m^2·s),热流密度范围19~28k W/m^2,系统压力0.7MPa和0.81MPa(饱和温度为26.8℃、31.4℃)和干度范围0~0.65。结果表明:质量流速对换热系数的影响较大,随着质量流速的增大而增大;在低干度区,热流密度对换热系数的影响较大,换热系数随干度的增加近似成单调增加;系统压力对换热系数也有明显的影响;将试验结果与Sun-Mishima公式和Liu-Winterton公式进行比较,发现试验结果与Sun-Mishima公式计算值吻合度较高,最大误差为14.1%。

An experimental study on two -phase flow boiling of R134a was conducted with a horizontal smooth copper tube with an inner diameter of 2. 168mm. Tests were performed with a mass velocity of 725 to 910kg/m2 · s, and a heat flux of 19.0 to 28kW/m2 , saturation pressures of 0.7 and 0.81MPa （ saturation temperature of 26.8 and 31.4℃ ） and vapor quality from 0 to 0.65. The experimental results show that the heat transfer coefficients increase with the rising mass velocity. At the low vapor quality conditions, the heat transfer coefficients increase with the rising of heat fluxes. The heat transfer coefficients are affected slightly by the system pressures. The experimental data were compared with the calculated results by Sun - Mishima correlation and Liu - Wintertoncorreation, respectively. It was found that the experimental data fitted well with the calculations of Sun - Mi- shima correlation, and mean absolute error 14.1%.