Numerical study of the effect of flow patterns on contaminant removal in a hospital ward with symmetrical and asymmetrical inlet port arrangements

Abstract

The effect of flow patterns on contaminant removal in a hospital ward is studied numerically using the Reynolds Averaged Navier-Stokes (RANS) approach. Transient simulations are performed for three air changes and four ventilation systems. The contaminant is represented by a tracer gas (contaminant air) to study the airflow patterns, contaminant concentration, and contaminant removal in the hospital ward. The simulation is validated through two experimental studies using different ventilation systems, yielding a satisfactory agreement between the predictions and the experimental data. Numerical results indicate that flow patterns have a significant impact on the concentration and removal of contaminants, influenced by the building's geometry and the location of injection ports. In symmetrical arrangements of injection ports, the contamination concentration tends to be non-uniform in the x-z directions. The contaminant removal efficiency is the lowest (0.9322–0.9877) due to jet interference and the formation of dead zones by recirculation regions. In the asymmetrical arrangement of injection ports, the formation of recirculation zones in critical areas is inhibited, resulting in a more uniform contaminant concentration compared to other cases. The contaminant removal efficiency for the nine inlet ports presents the best performance (0.9944–0.99995), as jet interference is minimized and dead zones are eliminated. Furthermore, the overall concentration is <0.55 % for 9 ACH and 0.0048 % for 16 ACH in 1200 s. However, implementing more inlet ports (13) than in Case 3 affects the contaminant removal efficiency (0.9745–0.9991) due to jet interference. Therefore, according to the building geometry, a correct number of inlet ports and an appropriate distribution are essential in contaminant removal.