Introduction of a new definition for effectiveness of desiccant wheels

Abstract

In common air conditioning methods, both sensible and latent loads are handled by cooling systems. Utilizing desiccant, individual cooling and dehumidification processes are possible. In this paper, desiccant wheel operation has been investigated by experimental study. Experimental conditions include different climates (hot dry and hot humid) at different operating parameters (regeneration temperature and wheel speed). Due to the temperature and humidity measurements of inlet and outlet streams, the desiccant wheel efficiency in each definition was calculated. All experiments show that enthalpy of the outlet process air is notably higher than that of the inlet air. This event leads to a novel efficiency definition which presents the deviation of the outlet process air enthalpy from the inlet air enthalpy. By increase in the dehumidification efficiency, the adiabatic efficiency decreases, whereas it increases by the regeneration efficiency. Hence in some situations the adiabatic efficiency will have an optimum value. According to the adiabatic efficiency concept, it seems to be related to the coefficient of performance of the desiccant cooling systems.