The influence of the evaporator inlet conditions on the performance of a diffusion absorption refrigeration cycle

The purity of the condensate at the evaporator inlet on the performance of a diffusion absorption refrigeration cycle is examined under three configurations of sub-cooling. Three sub-cooling configurations were studied numerically: the no sub-cooling (nSC) configuration where the condensate flows directly to the evaporator inlet without sub-cooling, the partial sub-cooling (pSC) configuration where the condensate is sub-cooled by the refrigerant heat exchanger before the evaporator inlet and the full sub-cooling (fSC) configuration where the condensate is sub-cooled both by the refrigerant heat exchanger and the evaporator. It was found that for the same heat input the pSC configuration shows the highest cooling effect at the evaporator and therefore the highest COP. The influence of the evaporator inlet condition on the triple tube gas heat exchanger was also studied. It was found that the temperature at the evaporator inlet has to be as low as possible. Finally, the influence of the purity of the vapor phase at the rectifier outlet on the cycle performance was also studied. It was found that less effort has to be invested in the purification of the hot refrigerant vapor in the rectifier.