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

In Mediterranean countries, 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 cogeneration systems driving desiccant-based air handling unit, that represent interesting alternatives to conventional units based on vapour compression cooling only. In this paper, experimental tests performed on an air handling unit equipped with a desiccant wheel, coupled to a small scale cogenerator and an electric chiller are described. A cross-flow heat exchanger between process air and cooling air (cooled by an adiabatic humidifier) is used to pre-cool the process air exiting the desiccant wheel. The effect of the heat exchanger and of the humidifier, as well as that of the chiller performance, on primary energy requirements and CO2 equivalent emissions of the system is experimentally evaluated.