Numerical analysis of two-bed adsorption thermophysical battery

Abstract

Air conditioning systems powered by waste energy sources, such as solar-driven adsorption air conditioning systems, hold significant importance. The present study delves into the performance assessment of a silica gel-based adsorption thermophysical battery (ATB) under varying operational conditions. Advanced cycles featuring a two-bed configuration have been devised to enable semi-continuous operation and refrigeration. This novel design presents a compact ATB that integrates the evaporator and condenser within a single heat exchanger, referred to as the Evaporator-Condenser Unit (ECU), thereby reducing the overall size and cost of the ATB system. The operating and design characteristics of the two-bed adsorption system were thoroughly explored using a theoretical model developed through MATLAB software. Evaluations were conducted on various performance metrics of the ATB, encompassing the coefficient of performance (COP), cooling capacity, specific cooling power, adsorption isotherm, and kinetics. A theoretical approach was formulated using the lumped parameter (LPM) and modified Freundlich adsorption equations. It can be deduced that the inlet temperature of the hot coolant exhibited a direct proportion with both refrigeration effect (RE) and specific cooling power (SCP) while inversely affecting the coefficient of performance (COP). A decrease in coolant temperature from 313 to 303 K resulted in a noteworthy 13.4 %. Furthermore, it was observed that COP exhibited a direct proportionality with the flow rate of chilled and cooled water while inversely relating to the flow rate of hot water.