Effectiveness of Desiccant Coated Regenerative Wheels from Transient Response Characteristics and Flow Channel Properties - Part I: Development of Effectiveness Equations from Transient Response Characteristics

摘要

During steady operation, regenerative wheels are subjected to cyclic step changes in inlet properties. The equation for the transient humidity step response of a desiccant coated rotary air-to-air wheel is developed from physical principles using a model similar to that used for the sensible energy or temperature response. This fully developed flow model is used to derive a characteristic moisture transfer time constant in terms of four dimensionless flow-channel desiccant-coating properties and the time duration of airflow through the wheel. Since the moisture diffusion time delays within the desiccant coating are significant for typical energy wheels and often desiccant dryer wheels, an empirical term is introduced with this time constant to account for the effects of the duration of exposure in the two types of wheels.