Evaporator Structure Optimization Study Based On The Coupling Of Heat Transfer And Pressure Drop

At present, the refrigerants which are widely used in the air conditioning and refrigeration system are usually CFCs and HCFCs. However,they have a bad effect on the environment. Then,developing a new refrigerant is becoming a hot spot of current research. Existing single working fluid is difficult to fully meet the requirements of environmental, safety, thermal and economy performance, thus mixed refrigerants has become the most promising solution in recent years. HFC/HCs have important application value based on their good performance. As one of the key components in the air conditioning and refrigeration, the evaporator’s performance has a great impact on the entire system’s COP. The internal flow and heat transfer situations for the evaporator using mixed refrigerants are more complicated. In order to provide theoretical guidance for the design of evaporator, this paper attempts to establish the tube structure optimization model for R125/R600 a based on the coupling of heat transfer and pressure drop. The main research work are as follows:(1)The concept of performance potential evaluation criteria(PEC) for mixed refrigerants evaporation heat transfer performance potential has been presented in this paper. PEC becomes a useful tool for comparing among various refrigerants the relative frictional pressure drop energy loss.The concept of total temperature penalty factor(TTP) has been presented in this paper,which implies comparing the various refrigerants in terms of both heat transfer and frictional pressure drop.(2)The evaporator structure optimization model has been established based on the minimum of TTP.The effects of evaporating temperature, tube diameter on the optimal tube length have been analyzed.(3)The evaporator simulation model has been established to verify the reliability of simple theoretical model.It is been found that,About the optimization of evaporator length and heat flux the simulation results agreed with theoretical calculation data, for the optimal heat flux errors are within the permissible range.