Ventilation Effectiveness of Ceiling-Supplied Displacement Ventilation System for Office Room (Part 1) Comparison of Temperature and Contaminant Concentration Distributions under Different Ventilation Systems using Full-Scale Experimental Chamber

¹ Osaka University, 1-1, Yamadaoka, Suita, Osaka 565-0871, Japan
² Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan
³ Daikin Industries LTD, Technology and Innovation Center, 1-1, Nishi-Hitotsuya, Settsu, Osaka 566-8585, Japan

^* Corresponding author: yamanaka@arch.eng.osaka-u.ac.jp

Abstract

It is recognized that the displacement ventilation is a superior ventilation system for the infection prevention. There is, however, a problem for displacement system that the space for diffusers and vertical duct is needed. If it is possible to install the supply diffuser on the ceiling, the flexibilities of the supply diffuser layout will be increased, which will make the displacement ventilation more easily used.The aim of this study is to develop a novel ceiling supply displacement system using a large supply diffuser with honeycomb to straighten the airflow and make the low velocity air supply. In this study, the effect of supply velocity on the distribution of concentration of the gaseous contaminant emitted from person simulators was examined by full-scale model experiment.CO2 was used as a tracer gas, and three types of ventilation system were tested using the full-scale model chamber. As a result, the novel ceiling diffuser brought the value of 0.3~0.4 of exhaust concentration, depending on the supply flow rate. It can be said that the ceiling-supplied ventilation system developed with a novel supply diffuser can accomplish quite higher ventilation effectiveness than mixing ventilation even if it is not a perfect displacement ventilation.