Integration of the Active Desiccant Wheel in CHP System Design

A solid desiccant based ventilation system has been installed to provide ventilation, and cooling/heating as needed, to the Intelligent Workplace (IW) of Carnegie Mellon University, as part of the IW Energy Supply System (IWESS). Since its installation, extensive testing data have been collected and analyzed to characterize the operating performance and cost of each major component, namely the enthalpy recovery module, the active desiccant module, the heat pump module, and the overall system. It has been determined that the active desiccant wheel is expensive to operate due to the high price of natural gas in the current fuel market. In order to improve the energy efficiency and reduce the operating cost of the overall system, it has been proposed to regenerate the active desiccant wheel using the rejected heat from a bio diesel engine generator. Given the temperature and quantity of the rejected heat available, performance maps that relate the supply air temperature and humidity with various system operating variables have been constructed for the proposed integrated system, based on the predictions from an equation-based performance model of the active desiccant wheel. Using the IWESS project as a specific example, a procedure has been outlined for developing operating strategies for the active desiccant wheel integrated Combined Heating and Power (CHP) system.