Experimental Evaluation of the Ventilation Effectiveness of Corner Stratum Ventilation in an Office Environment

Abstract

An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation's effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.SV was proposed by Lin as a response to the requirements of some governments in East Asia for operating indoor spaces at elevated temperatures in order to conserve energy [9][10][11]. The new recommended indoor air temperatures have been set to (26-28 • C) in the Republic of Korea, (26 • C) in Chinese mainland, (25.5 • C) Hong Kong, (27 • C) Taiwan and (28 • C) in Japan for summers [12]. Since conventional ventilation systems are incapable of efficiently providing thermal neutrality in warm conditions, SV was devised to serve that purpose. The ventilation system is aimed at coping with higher room temperature and air movement and has been found suitable for cooling small to medium rooms [13]. Lin et al. [10] stated that with a properly designed supply air velocity and volume, location of diffusers and exhausts, SV has potential to maintain better thermal comfort with a smaller vertical temperature difference, lower energy use and better indoor air quality (IAQ) in the breathing zone. In addition, a comparison of the mean air temperatures in the occupied zone confirmed that SV offered the highest cooling efficiency, followed by DV, and in last place, mixing ventilation (MV) [14].SV draws on the strength of personalized ventilation systems. Personalized or task ventilation systems have been ranked as the most energy efficient and provide the best air quality in the breathing zone. However, such systems are inadequate because only limited ductwork can be installed in the occupied zone to avoid obstructions. Besides the limited ductwork, task ventilation systems cannot adequately cater for the mobile occupants within the occupied zone. SV supplies fresh air directly into the occupied zone in order to overcome the shortcomings of the task ventilation system while retaining the benefits of better indoor air quality and energy performance [15]. For example, owing to its low nonlinearity and fast response, the SV system can be used to offer differentiated air velocity, temperature and predicted mean vote (PMV) distributions to cater for individual occupant preferences in shared spaces [16,17].The underlying operation principle of the SV system is the supply of fresher air dire...

A Numerical and Experimental Investigation of a Confluent Jets Ventilation Supply Device in a Conference Room

“…The study was performed in a climate chamber (7.2 × 4.2 × 2.7 m 3 ) at the University of Gävle in Sweden, representing a typical conference room environment. The climate chamber is versatile and has previously been used to investigate different indoor environments, e.g., open-plan offices [17,41], classrooms [33][34][35]47], and small offices [15,48].…”

“…Tracer gas measurements were left running until the concentration levels became negligible. Previous laboratory studies using the same climate chamber and measurement procedure estimated the tracer gas measurements to have an accuracy of ±7% ( [15,41,48]).…”

On the Ventilation Performance of Low Momentum Confluent Jets Supply Device in a Classroom

“…The study was performed in a climate chamber (7.2 × 8.4 × 2.7 m 3 ) at the University of Gävle in Sweden, representing a classroom environment. The climate chamber is versatile and has previously been used to investigate different indoor environments, e.g., open-plan offices [30,46], classrooms [39,44,47] and small offices [48,49].…”

“…Energies 2020, 13, x FOR PEER REVIEW 4 of 24 been used to investigate different indoor environments, e.g., open-plan offices [30,46], classrooms [39,44,47] and small offices [48,49]. Four mixing SJ supply devices are installed in the room, see Figure 2, and each has a rectangular outlet (0.6 × 0.6 m 2 ) overlaid with plate to make an all-round slot of 0.02 m that issues a ceilingattached airflow jet.…”

“…Tracer gas measurements were left running until the concentration levels had become negligible. Previous laboratory studies using the same climate chamber and measurement procedure estimate the tracer gas measurements to have an accuracy of ±7% [46,48,49].…”