Analysis of The Ejector Critical Back Pressure to A Ejector Refrigeration System

In order to enhance the ejector performance, a model for the solar ejection refrigeration system used R134a as refrigerant has been established in this paper. The relationship between the ejector critical back pressure and the system working condition has been discussed. It is found that the critical back pressure increases with the evaporation and generation temperature. The critical entrainment ratio of an ejector is in direct proportion to the evaporation temperature, but is in inverse proportion to the generation temperature. With the back pressure increasing, the refrigeration system COP value keeps almost constant firstly and then reduced. When the generator temperature is at 358K and the evaporator temperature is at 283K, the critical back pressure will be equal to 0.96MPa, the ejector´s entrainment ratio is 0.27 and the system COP can attain to 0.24.