Experimental investigation on the effect of the switching frequency on the performance of a thermal wave adsorption heat pump

In this paper, a two modular zeolite water adsorption heat pump (AHP) based on the thermal wave concept has been experimentally investigated. Each module composes of two heat exchangers contained in a hermetic stainless steel vessel. The first heat exchanger is the adsorber/desorber located on the top of the vessel, while the second is the evaporator/condenser heat exchanger located on the bottom of the vessel. Throughout this work, the effect of the non-dimensional switching frequency, which has been introduced and theoretically investigated by Alam et al. [Int. J. Heat Mass Transfer 43 (2000) 4419–4431], on COP and the mean heating power of an adsorption heat pump has been experimentally investigated under one typical working condition of AHPs. The results showed that the switching frequency and adsorber/desorber flow rate have strong influences on both COP and the mean heating power. It has been also found that there is an optimum switching frequency corresponding to each flow rate, at which the COP attains its maximum value. The obtained optimum switching frequencies vary slightly from 0.28 at an adsorber fluid flow rate of 0.6 l.min-1 to 0.32 at 1 l.min-1