R32在倾斜微通道中流动沸腾换热的数值模拟

Numerical simulation on flow boiling of R32 in inclined microchannel

利用VOF(Volume of Fluid Model)多相流模型及相变模型,对不同倾斜角度下R32在内径为1 mm管道中的流动沸腾换热过程进行了二维非稳态数值模拟,模拟工况为:工质饱和温度为15℃,质流密度为100、300 kg/(m^2·s),热流密度为50、80 kW/m^2。结果表明,R32在流动沸腾过程中依次经过了泡状流、受限泡状流、弹状流、波状环状流、蒸干区和雾状流。随着管道倾斜角度的增加,大气泡出现的位置后移;在入口段,换热系数随着管道倾斜角度的增加而减小,在中间段和出口段,换热系数随倾斜角度的变化不明显;压降随着倾斜角度的增加而减小。

A VOF multiphase flow model and a phase-change model were used to simulate the flow boiling heat transfer process of R32 in microchannel with an internal diameter of 1 mm at different tilt angles,under the condition of mass flux ranging between 100 and 300 kg/(m^2·s),heat flux ranging between 50 and 80 kW/m^2 and saturation temperature of 15℃.The results show that R32 passes through the bubble flow,restricted bubble flow,slug flow,wavy annular flow,dry and mist flow in the process.As the tilt angle increases,the position where the large bubbles appear is shifted back.The heat transfer coefficient is gradually reduced during the change of the inclination angle from-90°to 90°in the inlet section;In the middle section and outlet sections,the influence of the inclination angle on the heat transfer coefficient is not obvious.The pressure drop decreases as the inclination angle increases.