Examination of effects of operating and geometric parameters on the performance of a two-bed adsorption chiller

Abstract

Abstract A detailed numerical model of a two-bed adsorption chiller has been developed to examine the effects of operating and geometrical parameters on its overall performance. The condenser and evaporator are considered non-ideal in the present model. Therefore, their energy balances and heat transfer equations are integrated with the distributed-parameter fully coupled model for the two packed-bed adsorbers. Initially, the effects of fixed values of evaporating and condensing temperatures were evaluated for different three cases and two cycle times, the percentage change in the cooling capacity (CC) and COP were varied between +12.3% to −18.5% and +4.7% to −5.6% for the given cases, respectively, compared to the basic model developed in this study. At a certain cycle time of 840\u202fs, the specific cooling capacity (SCC) and (COP) were increased significantly by about 42% and 68%, respectively, when the heat-transfer-fluid (HTF) flow changed from the case of laminar to the case of turbulent flow regimes. The parameters effects on theoretical chiller performance were in different manners. For examples; when the ratio of desorption/adsorption durations (TR) was adjusted to 0.782, both of the SCC and COP were maximized and enhanced by about 2.4% and 4%, respectively, compared to the basic model case. Regarding the impact of the fins’ number (Nfin), the SCC was doubled, reaching 305\u202fW/kgads, when the tubes of 50 fins each were replaced by those of 200 fins per tube, while the COP attained the maximum of 0.59 at Nfin of 130 fins compared to the COP of 0.555 at Nfin of 50 fins for each tube. Furthermore, the effects of fin height and tube length have been investigated.