Exergetic Optimization of Absorption Chiller Single Stage H2O-NH3 by Experiments Design Method

Abstract

Single stage absorption chillers using H2O-NH3 have received increasing research interest in recent years, in order to make them competitive with conventional refrigeration machines. This work presents a study on the performance of such tri-thermal machines, used for negative temperature refrigeration. The objective is to determine the values of the system operating temperatures that minimize the irreversible losses in the various heat exchangers. To do this, the overall exergy efficiency of the system has been expressed as a function of the various operating temperatures. This objective function is to be maximized with experimental design method. The normal probability plot of the residual indicates that the random errors for the process are drawn from approximately normal distributions. From the results, with exergy efficiency greater than 0.4, two operating modes are presented which can be with condensation temperatures below 32°C and above 38°C.