Young Kwon Yang

In South Korea, the gradual increase in particulate matter generation has received significant attention from central and local governments. Exhaust gas, which contains nitrogen oxides (NO_x), is one of the main sources of particulate matter. In this study, the reduction of NO_x using a coating material mixed with a titanium dioxide (TiO₂) photocatalyst was demonstrated. The NO_x reduction performance of the TiO₂ photocatalyst-infused coating was evaluated by applying the ISO 22197-1: 2007 standard. Subsequently, the performance was evaluated by changing the NO gas concentration and ultraviolet (UV)-A irradiance under standard experimental conditions. It was determined that NO_x reduction can be achieved even if the NO gas concentration and UV-A irradiance are lower than those under the standard conditions when the TiO₂ photocatalyst-infused coating was used. This study revealed that NO_x reduction can be realized through TiO₂ photocatalyst-infused coating in winter or cloudy days with a low solar altitude. It was also confirmed that compared with the UV-A irradiance, the NO gas concentration has a greater effect on the NO_x reduction performance of the TiO₂ photocatalyst-infused coating. These findings can be used to evaluate a variety of construction materials with TiO₂ photocatalysts in the future.

Windcatcher louvers are designed to capture air flowing outside a building in order to increase its natural ventilation. There are no studies that have designed the shape of the louver to increase the natural ventilation efficiency of the building. This study aimed to conduct a computational fluid dynamics simulation and mock-up test of a Clark Y airfoil-type windcatcher louver designed to increase the natural ventilation in a building. The following test results were obtained. The optimal angle of attack of the airfoil was calculated via a numerical analysis, which demonstrated that the wind speed was at its highest when the angle of attack was 8°; further, flow separation occurred at angles exceeding 8°, at which point the wind speed began to decrease. The results of the mock-up test demonstrated that the time required to reduce the concentration of fine particles in the indoor air was 120 s shorter when the windcatcher was installed than when it was not, which indicating that the time to reduce particles represents a 37.5%reduction. These results can be seen as reducing the energy consumption of ventilation in the building because the natural ventilation efficiency is increased.