Applicability of displacement ventilation and impinging jet ventilation system to heating operation

Abstract

Abstract This study aims to acquire an understanding of the fundamental feature of IJV and DV under heating operation. Full‐scale experiments were conducted under these two different systems and supply air conditions along with temperature distribution and ventilation effectiveness. A wall surface of the test room was cooled as a heating load, and heating elements simulating occupants were located as internal heat load and contaminant emission source. Three cases of supply temperature were tested and the flow rate was also varied correspondingly. The position of the supply terminal was also changed to see its effect on heating performance, that is, mounted on the interior/exterior wall. For DV, the temperature/contaminant distribution differed significantly depending on the supply conditions, while that of IJV remained almost the same as a perfect mixing condition. Generally, IJV can achieve better temperature distribution compared to DV; however, the ventilation effectiveness of DV was superior to that of IJV with large supply flow rate. The correlation between the Archimedes number based on supply conditions and indices expressing local temperature and ventilation effectiveness is obtained. For IJV, the position of the terminal was found to have a larger impact on air distribution than the supply flow rate, while the opposite feature was obtained for DV.

Keywords

• impinging jet ventilation
• displacement ventilation
• space heating
• ventilation effectiveness
• full‐scale experiment