Research On The Performance Of Jet Supercharging Dual Evaporative Temperature Air Conditioning Refrigeration System

For the problems of high irreversible loss of heat transfer temperature difference and high power consumption of compressor in existing air conditioning and refrigeration systems,an ejection compression suction pressure-enhanced direct-expansion air-conditioning refrigeration system with double evaporation temperature is proposed,which can separately process sensible heat and latent heat of air to realize the independent control of temperature and humidity.The mathematical model of the thermal performance of the refrigeration system is established and the effects of high and low evaporation temperature,condensation temperature and indoor population on the performance of the system are discussed.The results indicated that with the increase of condensation temperature,the COP of the system decreases and the power consumption of the compressor increases;with the increase of temperature evaporation temperature,the COP of the system increases and the power consumption of the compressor decreases.With the increase of the number of persons in the room,the heat humidity ratio of the air-conditioning room decreases,and the energy efficiency ratio of the system also decreases.However,compared with the traditional compression refrigeration system,its COP is still 13.1% higher.When the heat humidity ratio is reduced by 1%,the COP is reduced by about 2.1% on average.For air treatment,the supply air volume of the dual temperature air conditioning system is far less than that of the traditional compression refrigeration system,so it can reduce the fan power consumption of air handling unitAs the key equipment of the system,the outlet back pressure of the ejector has a great impact on its performance.When the back pressure increases,the injection coefficient of the injector first remains unchanged and then rapidly decreases.When the back pressure increases to a certain value,the ejector will produce reverse suction.The inlet diameter of the suction chamber has little effect on the flow field,but only on the mass flow of the ejected fluid into the suction chamber.With the increase of the inlet diameter of the suction chamber,the injection coefficient slightly increased,but the increasing degree was not obvious.The length diameter ratio of the mixing chamber has a great influence on the performance of the ejector.When the length diameter ratio is too small,the injection coefficient of the ejector will be reduced.However,when the ratio of length to diameter reaches a certain value,the injection coefficient of the ejector remains basically unchanged.In order to achieve the best ejector performance,the length-to-diameter ratio of the mixing chamber should not be less than 10.The diffusion angle of the diffuser section has a certain influence on the performance of the ejector.When the diffusion angle is too large,the refrigerant after complete mixing can not reach the outlet back pressure at the outlet of the diffuser section,so the diffusion angle should be about 4?6°.In addition,based on the Redlich-kwong equation of state,the difference between the ideal gas model and the real gas model is compared in this paper,and the error is about 4.73%.Finally,for the R22 refrigerant adopted to drive the ejection compression suction pressure-enhanced direct-expansion air-conditioning refrigeration system with double evaporation temperature,convergent nozzle is used instead of the Laval type nozzle.The improved ejector is in good agreement with the design value after CFD simulation,and the injection coefficient increases about 0.3037.