Exergy Analysis of a Vapor Absorption Heat Transformer Using Modified Guoy–stodala Equation

Abstract

In the present work, thermodynamic analysis of a Lithium bromide-water-based absorption heat transformer (AHT) is done using a mathematical model. The study includes exergy analysis with the introduction of external°uid arrangements working as the interface of heat exchange for the various components of the model. Quantitative results are obtained for a set of inputs and modi¯ed Guoy-Stodala equation is used to include the real heat exchange temperatures in the study. These results are compared to the classical approach. It is observed that the total irreversibility calculated by the modi¯ed approach comes out to be 26.1% more than the exergy destruction obtained by the classical approach. Next, di®erent operating parameters are varied to understand the e®ect of these on exergy destruction using a computer programme code. Thus, a conclusion is drawn in the form of graphs, as to how the system performance can be improved. Using the concept of irreversibility, the study¯nds that the performance of the system can be enhanced by decreasing the temperature of evaporator and generator or by increasing the temperature of condenser and absorber. Nomenclature h : Enthalpy (kJ/kg) _ m : Mass°ow rate (kg/s) P : Pressure (kPa) _ Q : Heat rate (kW) T : Temperature ( C) T eff : E®ective temperature ( C) X : Mass fraction of solution s : Speci¯c entropy (kJ/kg Á K) T 0 : Environment temperature ( C) COP : Coe±cient of performance _ S gen : Entropy generation rate (kW/K) EXD : Exergy destruction rate (kW)