Modelling and analysis of a desiccant cooling system using the regenerative indirect evaporative cooling process

This paper focuses on the numerical modeling and analysis of a Desiccant Cooling (DEC) system with regenerative indirect evaporative cooling, termed Desiccant Dewpoint Cooling (DDC) system. The DDC system includes a Desiccant Wheel (DW), Dew Point Coolers (DPCs), a heat recovery unit and a heat source. Heat is used for dehumidification, whereas water is used for cooling and electricity for auxiliaries. An empirical DW model is built based on polynomial fits to manufacturer data. The DPC model is based on first principles, implementing heat and mass transfer using a 1D finite volume scheme and validated by manufacturer data. The models enable calculations of the steady state operation of the system. Alternative electric and absorption chiller-based systems are also modelled for benchmarking. The systems are simulated covering the internal loads of a specified supermarket during the summer period in different climates: temperate in Copenhagen and Mediterranean in Venice. Cheap and clean heat sources (e.g. solar energy) strongly increase the attractiveness of the DDC system. For the Mediterranean climate the DDC system represents a convenient alternative to chiller-based systems in terms of energy costs and CO2 emissions. The electricity consumption for auxiliaries in the DDC system is higher than in the chiller-based systems. The number of commercial-size DPC units required to cover the cooling load during the whole period is high: 8 in Copenhagen and 12 in Venice.