Preliminary study of cooling performance of novel PCM-desiccant cooling for buildings

Besides its hot ambient temperature, the tropical humid region also suffers from exceedingly high humidity. This high humidity to some extent limits the passive cooling ability for this climate. For instance, high ambient humidity limits the capability of evaporative cooling strategies. Another example is a phase change material (PCM), which is widely used in a climate with high diurnal temperature differences and can be effective for a climate with a comfortable range of humidity. However, in a near-saturated air of tropical humid climate, a temperature reduction without a similar decrease in humidity will still feel uncomfortable for building occupants. In many air conditioning systems, it is common to use a dehumidifier such as desiccant material to control the ventilation air humidity. In a passive cooling scenario, however, it is not beneficial to use desiccant alone to dehumidify the inlet fresh air because the ventilation air may become too hot for a room. To overcome this issue, we proposed a novel PCM-desiccant material composed of solid desiccant and porous aluminosilicate foam impregnated with phase change materials (PCM) panel, which can minimise the dehumidified air temperature. The material was installed into an air channel system along with another two PCM to optimally reduce the processed air temperature. A preliminary study using computational fluid dynamics (CFD) simulation with ANSYS Fluent was conducted to test the potential temperature and humidity reduction from the system compared to the conventional desiccant. Parametric studies on the effect of various inlet air temperatures, air flow rates, and relative humidity values on the PCM-desiccant cooling system were also carried out. The results showed that in the optimal condition, the novel PCM-desiccant cooling could achieve 4°C temperature reduction and 53% humidity reduction.