Simulation research on absorption refrigeration system based on NH3-H2O-LiBr vapor-liquid equilibrium calculation model

Abstract

In order to investigate the ammonia + water + lithium bromide absorption refrigeration cycle process and to simulate it accurately, a vapor-liquid equilibrium calculation model was proposed to obtain thermodynamic characteristic data of the ternary mixtures. The calculation of parameters of liquid phase is based on Wilson?s equation and NRTL equation. The vapor phase, assumed to consist of ammonia and water only, is described by The Redlich-Kwong Equation of State. The data of the equilibrium vapor pressure and the ammonia concentration in liquid phase calculated by this model was compared with the experimental data, the difference is between 0.5% to 9.6% within the temperature range from303 K to 425 K. The COP obtained by the simulation matches with that obtained by experiment and the absolute deviation is less than 0.02. Therefore, this calculation model can be used for simulation to extend the temperature range and pressure range of the system, so as to determine the design parameters of the absorption refrigeration system. The simulation results indicates that under different working conditions, the optimal generator temperature and concentration of adding lithium bromide can be selected, to which the theoretical explanations were given in this paper.

Compressor-Aid Absorption Chiller Working on Low Grade Temperature Heat Source: A Thermodynamic Analysis

“…Gao et al [22] suggested using R290/oil as fluid working. Arshi and Sudharsan [23] performed a thermodynamic analysis of single effect chiller into two cases of working fluids as LiBr-H2O and LiBr+LiI+LiNO3+LiCl-H2O; they found that the new combined system is better than the common one in term of generator temperature, while Wang et al [24] combined the NH3 with the LiBr-water as a new refrigerant for operating the absorption chiller. Moreover, adding some additives to the solution of LiBr-H2O is another way to modify the single effect chiller.…”