The Study Of The Steam Ejector Performance With R236Fa

The ejector is the key component of the ejector refrigeration system. To improve the ejector refrigeration system efficiency, we need improve the performance of the ejector. The ejector is theoretically, experimentally and numerically studied using R236fa as working fluid to analyze the performance of the ejector. The main research contents are as follows.(1) R236fa is selected as working fluid in the paper. Based on the calculation method of Sokolov and integrating fluid properties, the structures of the ejector with R236fa as refrigerant are designed.(2) The experimental and simulation results are compared. The average value of the entrainment ratio of the CFD simulation is about0.195. However, the average value of the entrainment ratio of the experiment is about0.160. The relative error is between10%and20%. The CFD results can be a very good experimental verification.(3) The performance of the ejector is investigated by CFD simulation. The results of the investigation are as follows. The working parameters and the structures of the ejector have a very important influence on the performance of the ejector. The design conditions are as follows:generator temperature80℃, evaporator temperature5℃, condenser temperature35℃and the cooling capacity2KW.①The working parameters of ejector include generator temperature, evaporator temperature and condenser temperature. With the increase of the generator temperature (80℃-84℃). the performance of the ejector will be improved. However, the performance will decrease when the generator temperature exceeds84℃. With the increase of the evaporator temperature, the performance will be improved. With the increase of the condenser temperature (32℃-35℃). the entrainment ratio remains unchanged. But the entrainment ratio will decrease when the condenser temperature exceeds35℃.②The structures of the ejector conclude the nozzle outlet angle, the distance of nozzle exit to mixing chamber, the diameter of mixing chamber, the length of mixing chamber, the length of diffuser and the angle of diffuser. The simulation conditions are designed as follows: generator temperature80℃. generator pressure1.2MPa, evaporator temperature5℃, evaporator pressure0.12MPa, condenser temperature35℃and condenser pressure0.35MPa. We study the influence of ejector structures to determine the optimal structure. It can be concluded that the ejector has the best performance, when the nozzle outlet angle of the ejector is8°, the ratio of the distance of nozzle exit to mixing chamber to the diameter of mixing chamber is0.95, the ratio of the area of mixing chamber to the area of nozzle throat is about4.21, the ratio of the length of mixing chamber to the diameter of mixing chamber is about4, the ratio of the length of diffuser to the diameter of mixing chamber is about5, and the angle of diffuser is10°.③The performance of the adjustable ejector is studied by adding on a needle in the ejector throat. The results show that the entrainment ratio will advance at first and then decrease with the distance of needle tip to the nozzle throat increasing. The entrainment ratio will be best when the distance of needle tip to the nozzle throat is13mm.