Performance of a single effect libr-water absorption chiller operating with a membrane-based microchannel absorber

Abstract

The simulation of a LiBr-H2O absorber using a porous fiber for the heat and mass transfer between the liquid solution and the refrigerant vapour is considered. Heat and mass transfer processes are modeled by means of selected correlations and data gathered from the open literature. For the case considered in this study, the absorber channels are 5 cm length. We evaluate the ratio between the volume of the absorber and the cooling capacity in a complete chiller, producing a reduction in size in the order of 1.5 times the usual values found in falling film absorption using conventional shell and tubes heat exchangers. The simulated membrane absorber is integrated in a single effect lithium bromide–water absorption chiller which performance is evaluated. The variable parameters are the external driving temperatures: final temperature in the desorber, the cooling temperature of the external fluid in the absorber and the condenser and the evaporating temperature. The coefficient of performance (COP) obtained varies from 0.5 to 0.8 for cooling duties ranging between 4 W and 7 W. The chiller response to different circulated solution mass flow rates is also presented.