Numerical investigation on saturated boiling flow and heat transfer of mixture refrigerant in a vertical rectangular mini-channel

Plate-fin heat exchanger with rectangular minichannels, as a type of high-performance compact heat exchangers, has been widely used in liquefied natural gas field. However, the studies on saturated boiling flow and heat transfer for mixture refrigerant in plate-fin heat exchanger have been scarcely explored, which are helpful for designing more effective plate-fin heat exchanger using in liquefied natural gas field. Therefore, in this paper, the characteristics of saturated boiling flow and heat transfer for mixture refrigerant in rectangular minichannels of plate-fin heat exchanger were studied numerally based on validated model. Then, the effect of different parameters (vapor quality, mass flux, and heat flux) on heat transfer coefficient and frictional pressure drop were discussed. The results indicated that the boiling heat transfer coefficient and pressure drop are mainly influenced by quality and mass flux while heat flux has little influence on them. This is due to the fact that the main boiling mechanisms were forced convective boiling and the evaporation of dispersed liquid phase while nucleate boiling is slight.