Numerical simulation of condensation heat transfer inside single square minichannel

A volume of fluid (VOF) model was adopted to simulate the condensation of R134a in a horizontal single square minichannel with side length as 1 mm and channel length as 50 mm. The effects of inlet mass velocity, heat flux, and mode of imposing cooling capacity on minichannel condensation were studied. The results show that condensation first appears at the corner of the channel, and then it is stretched on the effects of the surface tension until the whole channel boundary is covered. The local heat transfer coefficient decreases drastically on the head stream to a lowest value and then keeps almost unvaried. In the constant heat flux, the increased inlet vapor mass velocity has an impact on the enhancement of gas-liquid interface shear stress. As a result, the condensation film is thinner and the heat transfer coefficient gets higher value. While at constant inlet mass velocity, the effect of heat flux on heat transfer is unobvious. Compared with that exerted on a certain boundary intensively, cooling capacity uniformly exerted on channel boundary is more beneficial to condensation heat transfer with a uniform distribution of the liquid film. © 2016, Editorial Department of Journal of Southeast University. All right reserved.