The effects of the transient response and the energy cost are examined for performance evaluation of a desiccant system. The experimental system studied in this paper is a gas-fired, rotary dehumidifier that is commercially available. Partial transformation of latent cooling load to sensible load is intrinsic to hybrid air-conditioning systems incorporating desiccant technology for dehumidification. Due to the use of different sources of energy in a hybrid system, consideration of energy cost becomes imperative. An efficiency index is defined incorporating the relative costs of natural gas and electrical energy. This index can be used for feasibility studies of hybrid systems considering different utility rates. The widely used indices, such as coefficient of performance (COP) for desiccant systems or hybrid systems, are typically of thermo-dynamic importance and do not differentiate the sources of energy from the economic standpoint.

Units: Dual