Research On Main Factors Impacting Entrainment Ratio Of A Vapor Ejector

Nowadays,the research of renewable energy and waste-heat utilization has entered a new stage under the severe conditions of energy and environmental.In the field of refrigeration technologies,the ejector refrigeration system driven by low grade heat source stands out due to its advantages such as simple structure,low-cost and high reliability.The system whereas has a lower coefficient of performance.As the key unit of the system,the ejector is an important factor that influences the refrigeration coefficient of performance.In addition,the refrigerant is also an important factor which influences the system performance.On the basis of choosing the optimum refrigerant in this thesis,an experimental equipment of an ejector refrigeration system with high evaporation temperature is established for analyze the influence factors of ejector performance in the ejector refrigeration cycle,in order to provide basis for improving the efficiency of system.The research work mainly includes the following aspects:(1)Based on thermodynamic calculation model,the influences of different refrigerants to entrainment ratio of the ejector and the coefficient of performance of system were analyzed by using calculation program written in VC++ software and invoking thermo-physical properties of refrigerants in database of NIST REFPROP 7.0.Under design conditions,R245 fa was chosen as the optimal refrigerant.(2)The main influencing factors of ejector efficiency such as the state parameters of the primary fluid,secondary fluid and mixed fluid were discussed.The influence factors and its trend of entrainment ratio of the ejector were studied by thermodynamic calculation in order to provide theoretical basis for improving the performance of ejector.When the temperature range of generator is about 100~120 ?,the condensation temperature range is 35~50 ?,the calculation results indicate that both the entrainment ratio and the system coefficient of performance using R245 fa increase rapidly with the increase of evaporative temperature especially when evaporative temperature higher than 10 ?.(3)A vapor ejector refrigeration experimental system platform was designed and built.The design of the experimental system,the selection and the procurement of equipment,the construction and operation of debugging of the system were completed,which can be used for further experimental study.