Performance Evaluation of the Single-Stage Absorption Cooling System through Energy and Exergy Analysis

Abstract

Abstract In this study, a single effect (H2O-LiBr) water lithium bromide absorption cooling system is presented and evaluated by energy and exergy analysis. A mathematical thermodynamic model of the absorption cooling system has been found and derived from the basic principles of the first and second laws of the thermodynamics. The important parameters of performance are focused on the coefficient of performance COP and exergy efficiency. The performance was carried out over a range of operating conditions including the effect of generator, absorber and ambient temperatures. An energy and exergy investigation of separate system components were also obtained. The main obvious effect is detected for the situation of exergy efficiency for generator and absorber. The exergy efficiency increases with the rise of absorption temperature and a reverse effect is detected when the temperature of generator increases. The performance comparison of system components has been conducted in the present study. Exergy destruction of the generator was noticed to be 42% higher than exergy destruction in the absorber of 28%, due to the mixing of lithium bromide and water at high generator temperature of about 88°C. The COP of the absorption refrigeration system differs at the range (0.6 - 0.732) and maximum value was achieved at lowest temperature of absorber. The exergy analysis shows that the destroyed exergy distribution in the components of the system depends powerfully on the temperatures of system. The increasing in the generator temperature of higher than 88°C increases the COP of the current system, and with a additional increase in the generator temperature, the COP value stays constant. The obtained results lead to the documentation of factors that may affect the exergy efficiency of the (H2O-LiBr) absorption system. It was found that the efficiency of the exergy of the system increased as a result of the increasing in the ambient temperature from (25°C to 45°C). The results show that the influence of system components condition on the total exergy loss is very significant.