Experimental study and CFD modelling of four-bed hospital ward with all-air wall induction unit for air-conditioning. (15th August 2022)

• Record Type: Journal Article
• Authors: Sheng, Shaoyu; Yamanaka, Toshio; Kobayashi, Tomohiro; Choi, Narae; Chou, Nobukazu
• Is Part Of: Building and environment. Volume 222(2022)
• Publication Date: 2022-08-15
• Subjects: Induction air-conditioning -- Displacement ventilation -- Ward ventilation -- Full-scale experiment -- CFD modelling; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2022.109388
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: This study focuses on a prototype all-air wall induction unit. While maintaining the non-reheating and power saving conveying characteristics of the induction systems, this unit is water pipe free and has a low air supply velocity, and is therefore suitable for application in hospital wards. However, its ventilation and thermal performance have not been sufficiently investigated for further improvement. Thus, this study performs a full-scale experiment in which induction units are vertically installed in the ward's four corners. CO2 is generated to represent pollutants from a sample patient, and the steady-state temperature and CO2 concentration distribution are measured and analyzed under different supply conditions. Moreover, computational fluid dynamics (CFD) modeling methods are proposed and validated for this unit. The results show that the wall induction system can maintain a normalized concentration near the hospital beds that are away from the pollution source of less than 0.7 by producing displacement ventilation (DV). Supplying the air from the bottom half of the wall corner with a low supply rate while the bed is surrounded by a curtain can halve the CO2 concentration in the occupied zone by improving the efficiency of the DV. The vertical distribution of room temperature ranges from Δ3 °C to Δ4 °C depending on the supply volume, which is considered acceptable in the ward usage. Furthermore, in the ward CFD simulation, the accuracy of the Standard k-ϵ (SKE) model with specific heat transfer boundaries has been proved to be nearly identical to the low-Reynolds calculation results. Highlights: Wall induction unit can establish the displacement ventilation in the hospital ward. The prototype wall induction unit has satisfied ventilation and thermal performance. Curtains and air supply methods play a key role in the induction unit's performance. Decreasing the wall induction unit's height improved its ventilation performance. CFD modeling method of the wall induction unit was conducted and validated.