ADPI characteristics of line diffusers with perimeter heating load

초록

It is difficult to apply a conventional selection guide when the diffusere are installed in a perimeter region, because the air diffusion performance index vs. throw/length ratio curve listed in the conventional guide does not consider the perimeter heating load through the walls. The purpose of this study is to evaluate the characteristics of the air diffusion performance indices of a high sidewall line diffuser and a ceiling line diffuser and to propose a selection guide for a line diffuser when the perimeter heating load exists. A high sidewall line diffuser and a ceiling line diffuser were installed into a test room according to the ISO standard 5219. The velocity and temperature distributions and the air diffusion performance indices are obtained by the numerical calculation when the air flow rates are 425, 730, and 950 CMH and the heat load ratios are 0, 0.25, 0.5, and 0.75. The air diffusion performance indices from the numerical calculation results are compared with the existing experimental data to verify the evaluation method of air diffusion performance indices proposed in this study. When a sidewall line diffuser is installed in a high position in the test room the air diffusion performance index decreases with the increase of the flow rate on every heat load ratio except 0.75. In the case of ceiling line diffuser, the air diffusion performance indices are fixed when the heat load ratios are 0 and 0.25. When the heat load ratios are 0.5 and 0.75, they gradually increase until they reach 730 CMH. As a result, we produced air diffusion performance index curves with and without the sidewall heating. Therefore, it is possible to assume that the throw length guarantees more than 80% of air diffusion performance index with heating load on the wall.