Jun Yoshihara, Toshio Yamanaka, Narae Choi, Tomohiro Kobayashi, Noriaki Kobayashi, Aoi Fujiwara
This research introduces the local exhaust system (hood) into the consulting room to prevent airborne infection, especially for close-distance conversion. The hood’s capture efficiency is mainly affected by surrounding air flow, so this research compared three various underfloor air distribution systems (UFAD); floor-supply displacements ventilation (FSDV), displacement-flow-type diffuser, and swirling flow type diffuser. FSDV is a displacement ventilation method where SA comes from the whole floor through carpets or panels, forming a tranquil up-flow. A displacement-flow-type diffuser forms thermal stratification by supplying horizontal flow along the floor. Swirling-type flow diffuser supplies up and swirling flow and mixes room air well. Droplet nuclei or microdroplets leaked from the hood should be exhausted without expanding to reduce infection risk. The lower hood capture efficiency is not directly relevant to the higher infection risk, and the route to the exhaust outlet could be significant. For this reason, FSDV is expected to reduce the infection risk for close-distance conversion compared to a swirling flow-type diffuser. Full-scale experiments were carried out in this research to reveal the relationship between the ventilation system (hood and three UFAD systems) and infection risk.
