Abstract
In this study, confluent jets ventilation (CJV) supply devices with three different nozzle arrays (1 × 19, 2 × 19, 3 × 19) were investigated both numerically and experimentally at two different airflow and supply air temperature set-ups. The performance of the CJV supply devices was investigated concerning thermal comfort, indoor air quality (IAQ), and heat removal effectiveness in a conference room environment. A comparison between the experimental and numerical results showed that the ϑ2¯−f model had the best agreement out of the investigated turbulence models. The numerical results showed that the size of the array had a great impact both on near-field development and on the conditions in the occupied zone. A larger array with multiple rows and a lower momentum conserved the inlet temperature and the mean age of the air better than a single-row array with a higher momentum. A larger array with multiple rows had a higher IAQ and a greater heat removal effectiveness in the occupied zone because the larger array conserved the mean age of air better and the buoyancy driven flow was slightly better at removing the heat. Because of the lower inlet velocities, they also had lower velocities at ankle level, which decreased the risk of draft and thermal discomfort.
Highlights
Heating, ventilation, and air conditioning (HVAC) systems account for about 50% of the total energy use in buildings and more than 10% of total national energy use [1]
Due to the entrainment of the surrounding air, the confluent jet stream became wider and the maximum velocity decreased with distance from the inlets
The airflow followed the ceiling until it hit the wall opposite of the supply device and entered the wall zone, where it had higher velocities in the center of the confluent jet
Summary
Ventilation, and air conditioning (HVAC) systems account for about 50% of the total energy use in buildings and more than 10% of total national energy use [1]. The aim of ventilation is to maintain a comfortable indoor climate and indoor air quality (IAQ). It is important to design ventilation supply devices that utilize energy-efficient ventilation strategies that are appropriate for the constraints of the ventilated space. The most documented and well-defined ventilation strategy is mixing ventilation [2]. The principle behind mixing ventilation is to dilute the contaminated air in the room by supplying fresh air at higher velocities (often at ceiling level) to mix the air and lower the concentration of contaminants. The mixing conditions generally generate good thermal comfort and a uniform indoor environment.
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