| In the two-phase flow ejector refrigeration system(TPEFR),the gas-liquid separator is one of the more important component.The entrainment ratio of the ejector can be raised by using a suitable gas-liquid separator,thus the performance of the TPEFR system can be improved.The ejector is another more important component,and the traditional expansion valve is replaced by a two-phase ejector to recover the pressure energy of the high pressure refrigerant and to reduce compressor power consumption,thus improve the performance of the TPEFR system.In this paper the experimental device of the R134 a TPEFR system was built by using a re-designed gas-liquid separator to instead of the original one.The simulation and the experimental research on the performance of the components and the TPEFR system were carried out.Firstly,the internal fluid flow of the original and new gas-liquid separators were simulated numerically for 2-D and 3-D model by using FLUENT.The liquid and gas velocity cloud and liquid velocity distribution were analyzed.Then the CFX software was used to simulate the internal fluid flow in the two-stage nozzle ejector,and the simulation results were analyzed.Secondly,the experimental study on the performance of the R134 a TPEFR system was carried out,and the separation efficiency of the original and the re-designed gas-liquid separators was compared.The influence of the first throat equivalent diameters and the second throat diameters of the ejector nozzle on the performance of the ejector and the whole TPEFR system was analyzed.The experimental and simulation results were compared and analyzed under the same conditions.The conclusions are as follows:(1)The experimental results show that the gas-liquid separation efficiency of the re-designed gas-liquid separator is significantly improved.Under the same geometry of the ejector and the same operating conditions,the refrigeration capacity of the main evaporator is far greater than that of the auxiliary evaporator in the TPFER system with the new gas-liquid separator,and the main evaporator plays a major role.Compared with the original system,the percentage of the refrigeration capacity of the main evaporator accounting for the total refrigeration capacity in the new system is greatly improved.According to the different working conditions,the percentage is increased from original21.1%~27.8% to 82.2%~87.3%.(2)The experimental results show that the entrainment ratio of the ejector is significantly raised in the TPEFR system with the re-designed gas-liquid separator.Under the same geometry of the ejector and the same operating conditions,the entrainment ratio of the ejector in the TPEFR system with the re-designed gas-liquid separator is muchgreater than that of the ejector in the original system.According to the different working conditions,the entrainment ratio of the ejector is increased from original 0.2~0.46 to0.56~0.64.(3)The experimental results indicate that the total refrigeration capacity and the system COP of the TPEFR system with the re-designed gas-liquid separator is almost identical with these of the original system.But in the new refrigeration system,the refrigeration capacity of the main evaporator is dominant,and the evaporation temperature in the main evaporator is slightly lower than that in the auxiliary evaporator.Therefore,it can be thought that the energy quality of the new system is improved.(4)Compared the simulation and experimental results,it is found that with the increase in the equivalent diameter of the first nozzle throat,the entrainment ratios of the experiment and the simulation first decrease and then increase,and with the increase in the diameter of the second nozzle throat,they are on the trend of first increasing and then decreasing.The simulated entrainment ratio is larger than experiment one.And many experiments show that the first and second nozzle throat equivalent diameters can not be less than 1.8mm and 1.4mm respectively,otherwise,the experiment condition will not be able to maintain stable. |
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