Modelling of a desiccant-coated heat and mass exchanger for airflow dehumidification in HVAC systems

This work presents a numerical simulation of a heat and mass exchanger for the dehumidification of airflows in HVAC systems. It is called Desiccant-coated Thermally controlled Exchanger (DTE): it dehumidifies an airflow employing desiccant materials (adsorption/desorption processes) through a process with a limited rise in temperature. The physical and mathematical model of the device, integrating energy and mass balances, is shown. Silica Gel, Zeolite and Metal-Organic Frameworks (MOF) MIL 100 Fe are investigated. The results of adsorption and desorption processes are discussed, highlighting the promising potential of this device in HVAC systems. With a thickness of desiccant of 0.5 10-4 m, it is possible to reduce the inlet humidity ratio of 16.0 g/kg to levels of about 10.0 g/kg, required for standard air-conditioning applications, with a low increase in the outlet temperature. MOFs are the most interesting material, in particular for the low required regeneration temperature (50.0 °C) and the stability of the adsorption process. The findings demonstrate that the proposed model can facilitate the effective design of desiccant devices for HVAC dehumidification. Moreover, the paper emphasises how the utilisation of advanced desiccants can significantly improve the energy efficiency of HVAC systems, contributing to the decarbonisation of this sector.