Modeling the Effect of Heat Source Temperature on the Performance of Two-stage Air Cooled Silica Gel + Water Adsorption System

Abstract

Adsorption systems can utilize low grade waste heat (temperature <100 degrees C) or energy from renewable sources like solar for cogeneration i.e. cooling and desalination. The throughput and performance of such systems are sensitive to the available temperature difference between heat source and sink. This paper presents a modelling study of two-stage 2-bed air cooled silica gel + water adsorption system wherein the effect of heat source temperature variation in the range of 65-85 degrees C on system performance parameters viz. SCC, SDWP and COP are investigated for the first time. It is shown that the optimum half cycle time for SCC and SDWP increases from 1800 s to 2700 s as the source temperature decreases from 85 degrees C to 65 degrees C; thereby necessitating the use of adaptive cycle time control for maximum throughput. However, it is observed that the COP is relatively insensitive to such alterations.