Research On The Structure Parameters Influence To Air-Side Heat Transfer And Friction Characteristics Of Parallel Flow Evaporator

Parallel flow evaporator is a heat exchanger that appeared in recent years. Its raw material is cheap and its heat transfer efficiency is very high. So there is a good prospect in household air conditioning.The heat transfer and friction characteristics of the air-side have a great influence on the performance of the parallel flow evaporator. In this paper, firstly I used the energy balance method to build a heat transfer mathematical model and a physical model of the fins, then I made numerical simulations on those models and analyzed the temperature, velocity and pressure distribution of air near by the fin and got the relationships between pressure drop and heat transfer coefficient with face wind speed. And then an air duct experiment of a household air conditioning’s evaporator cores and an experienced computing were carried out. It obtained the relationship of resistance performance and heat transfer performance with the face wind velocity respectively by the combination of experiment, empirical formula calculation and simulation with regression analysis method, which verifies the validity of the model.Using this model as a basic model, and changing the structural parameters of the shutters (spacing and thickness of fin, angle、width and pitch of shutters) and face wind velocity, then I did simulations. And I got some relational conclusions about those factors’impacts on parallel flow evaporator’s air-side transfer and friction characteristics when face wind velocity is different by analysis temperature, velocity and pressure distribution of air nearby the fin.On the basis of the study it can get several parameters(spacing of fin, angle、width and pitch of shutters)that affect the performance of pin greatly, then quote the factor (j/f1/3) which can use to evaluate the characteristics of air-side performance, and use the idea of optimization method to optimize those several parameters. It discovers that:the wider the shutters, the better performance of the fin; and it exists a best shutters’ angle (28°), a best ratio between the pitch of shutters and the spacing of fin (1.3) which make the performance of the fin come to best.