Performance Prediction of Rotary Desiccant Wheel

In the desiccant dehumidifier using adsorbentsuch as silica gel and zeolite, outdoor moist airis dehumidified in adsorbent. On the otherhands, it is necessary for the adsorbent whichbecomes moist by dehumidifying outdoor air tobe dried (regenerated). Utilizing solar thermalenergy as a heat source for the regeneration ofthe adsorbent leads to large energy conservation.In order to spread the heating and hot-watersupply systems that utilize solar heat, it is oneley to find how to use the surplus solar heatduring summer, spring, and autumn seasons.Therefore, we are developing a wheel-type soliddesiccant cooling system using this surplus solarheat. We aim to develop the highly efficientdesiccant cooling system using solar thermalenergy and investigated a numerical methodwhich simulates combined heat and moisturetransfer processes inside a rotary desiccantwheel. The desiccant wheel is the maincomponent of a solid desiccant cooling system.In this paper, firstly, mass transfer coefficientthat has a great influence on thedehumidification performance of the desiccantwheel was derived from the experimental results.It is clarified that the mass transfer coefficientbecomes smaller with the decrease in therotational speed. Secondly, temperature andhumidity of the air that has passed through thedesiccant wheel were predicted using ournumerical method, and the validity of thismethod was examined by comparing calculationresults with measurement results. Finally, theoptimum rotational speed with changing thediameter of the desiccant wheel was discussed,using the numerical model.