Comparative Study on Two-Stage Absorption Refrigeration Systems with Different Working Pairs

The objective of this paper is to present a simulation study on the two-stage absorption refrigeration systems of 2.5 kW capacity using LiBr-H 2 O, NH 3 -H 2 O and R124-DMAC as working pairs. Under the design condition that the generating, absorbing, evaporating and condensing temperatures are 75 °C, 45 °C, 5 °C and 40 °C, respectively, the high and low pressure side solution circulation ratios and the coefficient of performance (COP) for the systems are calculated. Then the influences of medium, generating, absorbing, evaporating and condensing temperatures on system performances are analyzed. The results show that under the design condition, the COP of the LiBr-H 2 O system can reach 0.49, superior to those of the NH 3 -H 2 O and R124-DMAC systems, which are 0.32 and 0.31, respectively. Furthermore, the medium temperature for higher COP lies in an interval of 64–67 °C for the LiBr-H 2 O, NH 3 -H 2 O and R124-DMAC systems. High generating temperature and low absorbing temperature can decrease the high and low pressure side solution circulation ratios, and can also increase the COP. High evaporating temperature can decrease the low pressure side solution circulation ratio and increase the COP. Low condensing temperature can decrease the high pressure side solution circulation ratio and increase the COP.