Optimizing performance of a three-bed adsorption chiller using new cycle time allocation and mass recovery

Abstract

In this paper a new cycle time allocation for a three-bed silica-gel/water adsorption chiller is proposed and analyzed analytically. In this operating cycle lengths of all the phases are adjusted in such a way that it becomes possible to introduce mass recovery process. The result is increased cooling capacity and overall system performance. This new cycle time allocation is especially suitable for three-bed chillers driven with 60–65 °C heat source, because within this hot water temperature range the improvement of performance is the largest.The COP and SCP were calculated for a particular chiller described in the literature. Thanks to mass recovery the COP of analyzed chiller increased by 35% (from 0.268 to 0.362) at Thtf,in = 65 °C, and by 15% (from 0.350 to 0.405) at Thtf,in = 85 °C. Numerical optimization allowed to determine that at Thtf,in = 85 °C optimal mass recovery time is 8–12 s and the switching time is 27–35 s, while at Thtf,in = 65 °C optimal mass recovery time is 11–13 s and the switching time is 45–53 s.The COP of chiller running new operating cycle and cooled with Tcool,in = 30 °C is comparable to the performance of chiller running conventional operating cycle and cooled with Tcool,in = 25 °C. The SCP at Tcool,in = 30 °C and new allocation is comparable to the SCP at Tcool,in = 27.5 °C and conventional operating cycle.