Assessment of the adsorber surface density influence on the performance and operation of the intermittent SAR system

The adsorber surface density is a chief factor which is strongly coupled with other design parameters and climate conditions. This parameter has a considerable impact on the behaviour and operation of the intermittent solar adsorption refrigeration (SAR) system. This paper presents a theoretical investigation of the impact of the adsorption reactor surface density on the behaviour and overall performance indices of the intermittent SAR system. A water chiller which uses silica gel and water adsorption pair is studied under the climate conditions of Riyadh. The mathematical model is developed and a computer program is constructed to run the dynamic simulation of the chiller. Results obtained from the study show that the studied water chiller will fail to complete the cycle and to produce a cooling effect when the surface density is greater than 44 kg/m2. Moreover, the coefficient of performance (COP) increases with decreasing the surface density. Additionally, the optimum solar-to-cold conversion factor attains a value of 0.2 corresponding to surface density of 12.6 kg/m2 and COP of 0.43. This shows that the COP is not the accurate gauge for the SAR system performance and the solar-to-cold conversion factor is suggested when evaluating SAR system performance.