Thermal performance of PCM-to-air heat exchangers in hot desert climate

Abstract

Utilization of PCM-to-Air Heat Exchangers (PAHXs) in building free cooling applications has been reporting the insufficient cooling charging energy during the PCM solidification, which affects the overall system performance. This study reports the improvements in the cooling potential of the PAHX considering the climatic characteristics of the hot desert climate by taking the advantage of thermal radiation losses to the sky during nighttime. Parametric studies were conducted for the developed PAHX unit with respect to the location, airflow rate, and the PCM type. The improved PAHX unit was integrated into the mechanical ventilation system of an office space under hot desert climatic conditions considering various operational conditions. It was concluded that the PAHX unit outlet air could be directly supplied to the indoor space through a direct free cooling application to satisfy the cooling demand; also, it could be introduced to the mechanical cooling unit to minimize the energy consumption. The results showed that the thermal comfort levels were enhanced by up to 18%, and the cooling system energy consumption was reduced by 18.5% saving an amount of energy up to 10.8 kWh/week.