Effects of adsorbent conductivity and permeability on the performance of asolid sorption heat pump

Solid sorption heat pumps can improve the effectiveness with which energy r esources are used for heating and cooling. These systems operate by alterna tely heating and cooling beds of adsorbent material to produce a flow of re frigerant. The research presented here evaluates the effects of adsorbent t hermal conductivity and permeability on the performance of a thermal wave s olid sorption heat pump. In order to evaluate these effects, a numerical mo del of the thermal wave heat pump is developed. This model incorporates not only the effects of the conductivity and permeability, but also the effect s of the adsorption equilibrium properties, refrigerant properties, applica tion parameters, operating parameters, and bed geometry. For a typical air conditioning application, the model is used to study the influence of condu ctivity and permeability on the COP for systems using ammonia as a refriger ant. The results indicate that for the geometry considered, increasing the thermal conductivity of the adsorbent to 1 W/m-K can improve the COP to app roximately 0.75. Further increases in conductivity do not yield improved pe rformance. Furthermore, the reduced permeability associated with high condu ctivity adsorbents can impair vapor flow and lead to decreased performance.