Study on the improvement of the performance of a novel adsorption heat pump system for generating hightemperature steam

Performance of a novel adsorption heat pump system with zeolite-water pair for generating high-temperature steam is investigated. The adsorption heat pump system adopts a direct heat exchange method to overcome the low heat transfer rate between packed bed and heat transfer fluid. As a thermal storage process in the heat pump system, the regeneration of zeolite using dry hot gas is carried out. For a thermal discharge process in the heat pump system, water is introduced to the zeolite packed bed as not only adsorbate but also heat transfer fluid. A direct contact of water and zeolite results in evaporation of excess water due to the release of adsorption heat from zeolite. In the direct heat exchange method, large surface area of zeolite packed bed can be used for the convection heat transfer as well as the reaction. However pressure drop especially for introducing the dry gas would increase. Pressure drop is closely related to the blower load and should be therefore reduced for the practical utilization. In this study, reduction in the pressure drop during the regeneration of zeolite is investigated. An insert made of wire mesh is used to increase the porosity of the zeolite packed bed. As a result, while pressure drop can be reduced, the rate of regeneration of zeolite changes little. This can be attributed to the deviation of air flow by using the inserts. The appropriate conditions to reduce the pressure drop are studied.