Modeling study of two-stage, multi-bed air cooled silica gel + water adsorption cooling cum desalination system

Abstract

This paper presents a transient numerical study of two-stage, air-cooled silica gel+water adsorption system producing cooling and potable water. The key aspect of the present study is an attempt to model the inter-stage pressure dynamics when two beds exchange mass in terms of vapors across the stages. This is an important improvement over prior models wherein the inter-stage pressure was assumed to be either constant or user input. Furthermore, the evaporator and condenser pressures are also allowed to vary in this study in contrast to the previous papers. The simulation results are compared with the experimental data for various cycle times and chilled water inlet temperatures in the range of 11.5–20.0°C, while having the heat source temperature fixed at 85°C and air temperature at 36°C. Depending on the chilled water inlet temperature and cycle time, the SCC is found to be between 2 and 7Rton/tonne of silica gel; SDWP ranges within 0.3–0.9m3/day/tonne of silica gel and COP varies between 0.05 and 0.26.