Modeling and Analysis of Solar Assisted Adsorption Cooling System using TRNSYS

Abstract

Adsorption chillers are a favorable choice for solar based cooling system because of driving lower range of 50-85°C temperatures and therefore simple inexpensive flat plate solar collectors (FPC’s) can also furnish the desired energy. In this study three system configurations are analyzed to achieve 13 TR cooling demand load for an Islamabad (33.71° N, 73.06° E) located building for office. In configuration-I (C-I) returning fluid from adsorption chiller moves towards the hot water storage tank (HWST) connected to solar thermal collector whereas in configuration-II (C-II) returning fluid from adsorption chiller may be diverted from collector-HWST loop if temperature of water in HWST is less than the required temperature (i.e. 85°C). In third configuration C-III, HWST is not used. Therefore hot water from the outlet of solar collector directly enters in the auxilary heater (which will be switched on if required else off) and return water from adsorption chiller will become inlet of solar collector. The three system configurations are modeled and simulated in TRNSYS for the whole summer season to investigate the optimum collector tilt, least collector area for maximum solar fraction (SF), fractional primary energy savings (ƒPES) and monthly solar collector’s thermal efficiency. Simulation results showed that C-I gives comparatively higher collector thermal efficiency and ƒPES. For configurations C-I and C-II, the minimum required collector’s area for FPC is estimated to be 250 m² which is reduced to 150 m² for evacuated tube collector (ETC) and corresponding to those areas optimized size of HWST is estimated to be 10000 and 4500 liters for FPC and ETC respectively. For both collectors maximum seasonal solar fraction is obtained at a collector tilt of approximately 13°. C-III gives comparatively higher solar collector’s thermal efficiency as compare to C-I and C-II but C-III has comparatively low values of SF and ƒPES as compare to configuration-II and configuration-I for same FPC and ETC areas of 250 m² and 150 m² respectively.