A Study On Hot Liquid Defrosting Of Refrigeration System

The depravation of cooling and dehumidification of constant temperature and humidity air-condition because of frosting of evaporator and the fluctuation of temperature and humidity when the evaporation defrosts are key problems as the wide use of low temperature air-condition and low temperature and humidity constant system. in this paper, one new method of defrosting hot liquid defrosting has been researched both in theory and experiment.The inside defrosting model of evaporator was built, and the influence to defrosting process of different parameters of input defrosting medium has been studied by calculation with a Visual Basic computer program. The effect on time and consumed energy in defrosting process of input refrigerant temperature and initial frost thickness on the evaporator has been investigated, and the results display that although the defrosting rate of hot gas defrosting is more fast than hot liquid for the coefficient of heat transfer is far greater in two-phase flow than in single-phase flow, the advantage of hot liquid defrosting is obvious, So the phase of input defrosting mediums is important to the defrosting process as well as the temperature and flux.The differential pressure of evaporator is taken as the judgment of switch in the hot liquid defrosting experiment. It has been proved by the practice that the model built is valid, then the result from it is right. In the whole operation period both of cooling and defrosting process the fluctuate of temperature and humidity in the room would meet the requirement well, and the destructive effect to evaporator is small than with hot gas. Because the rejection of heat of the heating rod before air outlet is too little, the temperature and humidity in the control house fluctuate near by the requirement, If this can be improved , the precision of the system will better.