Experimental analysis of an unconventional desiccant-based air-conditioning system: the influence of cooling air flow and chiller on the energy and environmental performance

Nowadays, the increasing demand of summer cooling is typically covered by electric chillers, often determining electric peak loads and black-outs. Thus, a wide interest is spreading in small scale natural gas-fired cogenerators driving desiccant-based air-conditioning systems, which represent interesting alternatives to conventional systems based on vapor compression cooling only. In this article, experimental tests performed on an air handling unit (AHU) equipped with a desiccant wheel (DW), coupled to a small scale cogenerator and an electric chiller are described. A new layout of the desiccant-based AHU is investigated, considering a third flow (the cooling air), besides the process air flow and the regeneration one. A cross-flow heat exchanger between process air and cooling air is used; the cooling air, cooled by an adiabatic humidifier, is aimed to precool the process air exiting the DW. The relevant influence of the heat exchanger and of the humidifier, as well as that of the chiller performance, on global primary energy requirements, water consumption and CO2 equivalent emissions of the system is experimentally evaluated.