Thermodynamic study of a two-stage vapour absorption refrigeration system using NH 3 refrigerant with liquid/solid absorbents

Abstract

A systematic investigation is made of the two-stage vapour absorption refrigeration system employing the refrigerant absorbent combinations of NH 3H 2O and NH 3LiNO 3. The system consists of coupling two conventional absorption cycles so that the first-stage evaporator produces cooling water to circulate in the absorber of the second stage. The effect of operating variables such as generator temperature, evaporator temperature, absorber temperature and condenser temperature on the coefficient of performance (COP), heat transfer rates and relative circulation have been studied for both single-stage and two-stage absorption refrigeration systems. It is found that the COP is higher for NH 3LiNO 3 than for NH 3H 2O, in both single-stage and two-stage absorption systems, especially at higher generator temperatures. Furthermore, the minimum evaporator temperature achieved is lower for NH 3LiNO 3, and the system can be operated at lower generator temperatures.