A non-adiabatic desiccant wheel : modeling and experimental validation

Desiccant/evaporative cooling systems offer an environmentally friendly alternative to conventional vapor compression chillers. The desiccant wheel is the heart of this heat-driven cooling system. The main drawback of conventional desiccant wheels is the excessive heating of the supply air and desiccant material during dehumidification. This increases the partial pressure of water on the desiccant material and reduces the amount of moisture that can be removed from the air. To overcome this problem, a nonadiabatic desiccant wheel design has been investigated. This new wheel has an internal heat transfer structure with alternative channels for dehumidification and for indirect cooling of the dehumidification process. The supply air and regeneration air streams flow axially in opposite directions whereas the cooling air enters axially at the center of the wheel and exits radially, achieving simultaneous cooling and dehumidification of the supply air. A numerical model for this design is developed and a representative channel of the wheel was constructed to validate the model. Predicted modeling results show good agreement with experimental results.