Finite time thermodynamic analysis of the optimum temperature difference of integrative solar/air double source heat pump system

In this paper, the optimum temperature difference of integrative solar/air double source heat pump system(DS-SAHP) was analyzed through finite time thermodynamic analysis method. Both minimum system entropy production and largest refrigeration coefficient of the isolated system which was made up of heat source, cold source and heat pump unit were taken as the optimization objective function, the equations of optimum temperature difference between working medium and heat source under condition of the certain refrigeration rate were also given. According to the equations, the best heat transfer temperature difference of three different operating modes was calculated, respectively pure air model 9.7～14.1 ℃, the higher the heat transfer coefficient is, the smaller temperature difference, solar - air double source model 2.1～3.5℃, solar energy model 2.4～10.1 ℃, the limit value is 2.4 ℃, the stronger radiation, the smaller optimal temperature difference. The total solar radiation intensity of 480 w / ㎡ and 690 w / ㎡ can be used as the turning point of three kinds of mode of the DS-SHAP system, theory analysis results are in good agreement with the experimental results.