Effect of salt on the performance of ammonia absorption refrigeration cycle: A simulation study

Abstract

To overcome the drawbacks associated with conventional binary mixtures (NH3-H2O and H2O-LiBr) in the vapor absorption refrigeration system (VARS), salt is added to the NH3-H2O mixture. The present simulation study analyzes the influence of adding LiBr and LiNO3 salts within a salt mass fraction range of 0 to 35% on the coefficient of performance (COP) of the NH3-H2O cycle. The simulations are conducted using Aspen Plus software. Furthermore, the influence of generator temperature on the COP and evaporator capacity of the ternary NH3-H2O-LiBr and NH3-H2O-LiNO3 cycles are also studied. The simulation results demonstrate that adding LiBr and LiNO3 salts improves the COP and reduces the initial temperature requirement in the generator of the VARS. Specifically, the NH3-H2O-LiBr cycle achieves the highest COP of 0.645 at an NH3 mass fraction of 55% and a LiBr mass fraction of 25%. This represents an 8.81% improvement compared to the COP of the NH3-H2O cycle. Similarly, the NH3-H2O-LiNO3 cycle exhibits the peak COP of 0.603 with the same NH3 mass fraction and LiNO3 mass fraction of 20%, which is 2.2% greater than the COP of the NH3-H2O cycle. Under similar operating conditions, the COP of the NH3-H2O-LiBr cycle is greater than that of the NH3-H2O-LiNO3 cycle.