Two-Phases Evaporative Cooling for Better Outdoor Thermal Comfort in High-Density Tropical Cities: A Computational Parametric Study

Evaporative cooling technology, specifically the use of misting fans, have been adopted in many temperate countries to attain thermal comfort among occupants. Yet, many of these studies are conducted in small scale scenarios like Wind Tunnels, and no research has been done to study the synergy between the urban canyon and these systems. This paper seeks to address the above knowledge gap using CFD simulations with input data typical of a tropical country like Singapore. Existing misting systems can be broadly categorized into non-atomizing and atomizing sprays, and this paper seeks to study the impact on cooling for both systems in terms of reduction in air temperature. The results show that the urban canyon aspect ratio plays a significant role in determining the degree of cooling and area of coverage from misting systems, where even with significantly lower water mass flow rates, an aspect ratio of 2.5 can attain the same thermal comfort as that of aspect ratio 0.4. Also, high density areas with low wind flow tend to dampen the evaporative cooling impacts.