PERFORMANCE OF DESICCANT WHEEL AFFECTED BY ISOTHERM

摘要

The adsorption performance of a desiccant wheel directly determines the removed amount of thernmoisture from the air. With the demand of increasing COP, reducing the power consumption and loweringrndown the regeneration temperature, many kinds of new adsorbents are developed. The isotherm is therninherent property of adsorbents, and its shape will affect the adsorption capacity. Recently, it is deemed thatrnType S isotherm is one of the best shapes because at a wide range of the adsorption and desorption relativernhumidity, the saturation adsorption amount changes a little and it is easy to be reactivated. In the presentrnstudy a mathematical model, in which the moisture transportation inside the sorbent layer is calculated by thernFick’s law, is set up, and the predication accuracy of the model is verified by the experimental data. Then,rnseveral kinds of hypothetical isotherms are manually offered and the adsorption performances of desiccantrnwheel using these isotherms are compared. The study result reveals that the Type S isotherm is not the mostrnideal isotherm when it is applied into the real desiccant wheel because the variation of the relative humidityrnof the air along the flow direction in the adsorption channels will lead to the desiccant wheel working at itsrnworst range. Moreover, the linear type isotherm is always moderate.