Modeling and optimizing a two-bed adsorption cooling system with a modified mass recovery process

•Adsorption Refrigeration Cycle (ARC) with modified mass recovery process is proposed.•Energy and exergy analyses of ARC are performed.•The proposed two bed ARC is modeled and optimized for a specific cooling capacity.•Optimization is performed for COP and exergy destruction as two-objective functions.•Optimum values of COP and exergy destruction were 0.555 and 1719.6 kJ. A two-bed adsorption refrigeration cycle (ARC) with a new proposed modified mass recovery process is investigated (modeled, optimized and compared with ARC cycle with conventional mass recovery process) here. This proposed modified mass recovery process increases the system cooling capacity and cycle exergy efficiency. These achievements reached by opening the connecting valve between two beds during mass recovery process as usual, but continuing cooling of adsorption bed by water even during mass recovery process. Thus, the refrigerant vapor moved from desorber to adsorber bed in this situation by two effects, the higher pressure of refrigerant vapor in desorber bed and also due to higher effect of adsorption process for cooling of this bed by water. Furthermore, at the end of the proposed modified mass recovery process, the equilibrium pressure of beds was closer to the evaporator pressure than that for ARC with conventional mass recovery process. Thus, the new switched adsorption bed could connect to evaporator even during pre-cooling process. This makes connecting time period of evaporator and adsorber longer than that for ARC with the conventional mass recovery process. The above effects increased the amount of refrigerant vapor adsorbed in the adsorption bed which increased ARC cooling capacity as well. Finally to study the effects of various design variables, a two bed ARC with the proposed modified mass recovery cycle is modeled and optimized for a specific cooling capacity by considering coefficient of performance and exergy destruction as two objective functions. Results for a system with 14 kW (4 refrigeration tons) cooling capacity showed 0.555, 0.284 and 1719.6 kJ for optimum values of coefficient of performance (COP, with 0.9% increase), exergy efficiency (14% increase) and total exergy destruction (16.2% decrease), respectively in comparison with those for ARC with the conventional mass recovery process.