Thermal modelling and parametric study of two stage absorption refrigeration and air-conditioning systems

Abstract

This paper presents a thoermodynamic assessment of two stage absorption refrigeration and air‐conditioning systems. Two working fluids, namely water‐LiBr and NH3‐H2O as refrigerant‐absorbent combinations have been considered for the production of different cooling temperatures. Both the systems are assumed to be operated with hot water available from solar collectors. Thermal modelling and a parametric study of a two stage absorption system, based on thermodynamic analysis aided by computer, have been carried out in detail. It is found that the cascading of two stage absorption systems (in which the first stage evaporator produces cooling water to be circulated in the absorber of the second stage) can be easily operated to produce much lower temperatures suitable for refrigeration and air‐conditioning applications. The COP of a two stage absorption system is lower than that of a single stage; however, the second stage can be operated with lower generator temperatures than the first stage. However, there is an advantage for a two stage system because of the slow fall‐off in COP at higher generator temperatures.