Effect of the Working Fluid on the Ejector Refrigeration System

In this paper، the performance of an ejector cooling system and the effect of the following different working fluids such as water، ammonia، R134a، R141b، R12، R600 and R245fa are described and the effects of cycle parameters on the consumed heat and work and COP are studied. This cycle with the working fluid R141b has the least COP while the working fluid R₁₂ in comparison with the other working fluids has the most (0. 58 in comparison with 1 at Tg=78oC and Tc=15oC). For specific ejector geometry، in the cycle with water as the working fluid، the reversed flow in secondary inlet leads to inefficient ejector. So ejector with this specific geometry cannot be used in a cycle with water as a working fluid. An increase in operating temperature and a decrease in generator temperature cause an increase in the entrainment ratios (from 0. 63 to 1. 15 for R12) of ejector and coefficients of cycle performance (from 0. 54 to 1. 0 for R12). The system using ammonia as the working fluid has the most amount of power of generator، evaporator and pump، so this cycle needs a most heat supply in the generator and a bigger mechanical pump. The system using R141b has the least mentioned value and needs the lowest heat supply and smallest pump.