A parametric analysis on the effect of design and operating variables in a membrane-based desorber

Abstract

A parametric analysis of a membrane-based microchannel desorber working with H2O–LiBr is presented. Mass and heat transfer equations are solved, for different membrane properties and design and operating conditions. Sensitivity of the ratio between chiller cooling capacity and desorber volume (rqV) to changes in the following parameters is evaluated: width and height of solution and hot water channels; solution concentration, temperature, pressure and mass flow rate; hot water temperature and mass flow rate; membrane porosity, pore diameter and thickness; thickness and thermal conductivity of the wall between solution and hot water and vapour pressure. The analysis includes direct diffusion and boiling modes. In both cases, during design, most important parameters to maximize rqV are solution channel height and wall thickness. Additionally, effect of channel length is remarkable during boiling. Good operation requires adequate inlet concentration and hot water temperature. In direct diffusion, vapour pressure is also a relevant parameter.