微细管道内R141b沸腾气液两相 流动与换热特性数值仿真

In order to investigate the flow and heat transfer mechanism of gas-liquid two-phase in micro/mini-channel,the flow boiling heat transfer of the refrigerant R141b in horizontal micro/mini-channel was simulated using VOF multiphase flow model. The distribution of two-phase flow regimes,temperature,velocity and boiling heat transfer coefficients were obtained. The characteristics of the flow boiling heat transfer and bubble movement were analyzed. The results show that two-phase flow pattern maps in horizontal micro/mini-channels include single phase flow,bubbly flow,confined bubble flow,slug flow,intermittent flow,mist flow,and so on. Vapor quality,temperature and velocity increase gradually along the axial direction,the boiling heat transfer coefficients increase firstly and begin to decrease after the peaks. As the increase of the mass velocity and heat flux,boiling heat transfer coefficient increase significantly. This is because that the flow velocity of the refrigerant increases with the increasing mass flux and the velocity of liquid phase transition to gas phase increases with the increasing heat flux. On the same conditions of heat flux,the heat transfer coefficient in the conditions of large mass flux increased 21.4% averagely than the small mass flux. On the same conditions of mass flux,the heat transfer coefficient in the conditions of large heat flux increased 23.9% averagely than the conditions of small heat flux.