Theoretical And Experimental Study On The Performance Of The Evaporator Using The Recycle Refrigerant

Research of refrigerating installation's energy saving is concentrated on the four major components: compressor, throttling set, heat exchangers. Improvement of evaporator performance is of more importance, this paper put forward a method for augmentation of evaporator heat exchange from the new view: taking advantage of thermal-siphon principle to make refrigerant recycled, and evaporator get multiple supplied liquid. In this way the contact between refrigerant and inner surface of evaporating coil can be increased, so heat transfer performance, the coefficient of heat transfer and efficiency of evaporator can be improved.In this paper, a heat transfer model of evaporator using the recycle refrigerant was established, and the resistance equilibrium analysis of two-phase flow for recirculating systems were done, so the relation of heat load, pressure head of liquid supply, pressure drop, circulating rate, heat transfer coefficient, and heat transfer temperature difference can be obtained. On the basis of it, referring to the design method of evaporator, this paper summed up the design method of evaporator using recycle refrigerant.By the means of the experiment of recirculating refrigeration system which was set up by ourselves in the different operating conditions, performance characteristics were obtained preliminarily. And contrast experiments between recirculating and ordinary refrigeration system were carried on, performance characteristics difference of the two refrigeration system was found out. Though analysis of experimental data, the mathematical model was proved, and the mathematical model was applied to do theoretical calculation for the evaporator using recycle refrigerant in the lower temperature operating conditions.Investigations presented in this paper indicate that the low temperature evaporator using recycle refrigerant which is based on the thermal-siphon action can recycle the refrigerant, and it has much better heat transfer characteristics and efficiency, moreover, it doesn't has more additional energy consumption. Theoretical calculation implies that, compare to ordinary evaporator, refrigerating capacity of evaporator using recycle refrigerant can increases by about 30%, and the heat transfer coefficient can increases by about 50% in the lower operating conditions.