Investigation of the cascade type of hybrid adsorption-vapor compression chiller

Abstract

A numerical analysis was performed on a hybrid cooling system consisting of an adsorption chiller (ADC) and a vapor compression chiller (VCC) operating in a cascade mode. The system was evaluated for its overall performance and energy savings compared to standalone ADC or VCC cooling systems. The ADC utilizes an RD silica gel/water working pair, while the VCC uses R410A refrigerant. The cooling strategy involves the ADC providing cooling for loads up to 10 kW, with the VCC supporting the ADC when cooling loads exceed 10 kW, up to 15 kW. MATLAB and Refprop were used to model the system, and the results were consistent with prior research. The study examined the effects of adsorption cycle time, hot water temperature, cold water temperature, adsorbent particle size, and intermediate mass flow rate. Additionally, the performance of different adsorbents, including CaCl2 bound to mesoporous silica (SWS-1L) and Ferro-aluminophosphate (FAM-Z01), was compared to RD silica gel. The hybrid system reduced compressor work by 94.57% and 97.69% compared to conventional VCC when the hot water temperature was set to 90 °C, and cold water temperature was set to 26 °C, respectively. The hybrid system achieved the highest energy savings and overall coefficient of performance, with SWS-1L achieving a 91.37% energy savings and a 6.71 coefficient of performance. Therefore, the cascade-type hybrid cooling system is a superior alternative, particularly for cooling loads ranging from 10 kW to 23 kW, offering significant energy savings compared to conventional VCC systems.