Performance Analysis Of The R290 Dual-temperature Evaporating Ejector Expansion Refrigeration Cycle

The rapid development of society has caused the huge energy consumption and serious environmental problems,and the energy consumption of refrigeration and air conditioning equipment is an important part of the consumption,at the same time use of freon refrigerant can cause the environmental issues such as ozone depletion and greenhouse effect,so the energy saving and environmental protection has been the subject of the refrigeration technology development.The throttle valve in the traditional vapor compression refrigeration system is the main component that causes the energy loss of the system.So using the ejector to replace the expansion device is an effective energy saving technology.A R290 dual-temperature evaporation ejector expansion refrigeration cycle(DEEEC)is presented in this paper.The ejector is used as the expansion device at the outlet of the condenser.Based on the thermodynamic analysis method,a mathematical model of the novel cycle was established,and the influences of various operating parameters on the performance of the cycle,such as the pressure drop of the ejector,the load ratio of the high and low temperature evaporator,the condensing temperature,the evaporation temperature,the degree of sub-cooling and the efficiency of the ejector components,were explored.And the proposed cycle are compared with the dual-temperature evaporation vapor compression cycle(DEVCC)and the previous condenser outlet split ejector cycle(COSEC).CFD method was used to simulate the ejector,and the influence of the size of the ejector structure on the entrainment ratio was explored.The research results showed that under different operating conditions,compared with the dual-temperature evaporation vapor compression cycle,the dual-temperature evaporation ejector expansion cycle’s COP and exergy efficiency are significantly increased.And the high and low temperature evaporator load is bigger,the condensation temperature is higher,low evaporation temperature and smaller sub-cooling degree under the condition of system performance improvement is more apparent,For example,when the condensation temperature is 45℃ and the evaporation temperature is 5℃,the COP and exergy efficiency of the novel cycle are 6.515 and 0.318 respectively,and the improvement rate is 35.33% and 36.65%respectively.Compared with the condenser outlet split ejector cycle,the proposed cycle also has certain advantages under some working conditions.In addition,the exergy analysis results also showed that the use of ejector could significantly reduce the irreversible loss of the system caused by the expansion of high-pressure refrigerant.Under the same working conditions,the exergy loss coefficient and exergy loss rate of the expansion equipment in the system could be reduced by 79.25% and 76.65%,respectively.Finally,the numerical simulation results show that increasing the diameter and length of the mixing section in a certain range is beneficial to the increase of ejector entrainment ratio,while increasing the outlet diameter of the motive nozzle will lead to the decrease of entrainment ratio.The research results of this paper are of great significance for the performance improvement of the dual-temperature evaporation refrigeration system and the design and application of the novel dual-temperature evaporation ejector expansion refrigeration system.