In 2020, the rapid spread of COVID-19 led to a global pandemic. To mitigate the risk of infection from droplets and aerosols, acrylic partitions were installed worldwide, and room ventilation became mandatory. However, conventional flat partitions allow aerosols from coughs or sneezes to diffuse back into the room after reaching the partition. To address this issue, the authors developed a partition with devices attached at the top and bottom to prevent aerosol diffusion. The present study investigated the effectiveness of this partition through numerical analysis and flow visualization experiments using real cough and sneeze exhalation volumes. Results from particle image velocimetry (PIV) analysis using video images from flow visualization experiments and numerical analysis indicate that the device effectively directs exhaled airflow to prevent diffusion. Additionally, the study examined the impact of forced suction volume and suction area, provided by a small fan attached to a preventive aerosol diffusion unit, on the rate of exhaled air collection.

Maintaining a healthy and safe indoor environment with high energy efficiency remains challenging in the era of carbon neutrality and post-COVID. In this study, we focus on improving air quality in four-bed hospital wards by proposing and verifying the performance of a vertical induction air conditioning system with high ventilation efficiency. The vertical induction system effectively combines the benefits of induction air conditioning, such as reduced power requirements for air conveyance and elimination of reheat. Additionally, this system is designed to employ displacement ventilation, which is anticipated to enhance ventilation efficiency significantly. Through full-scale experiments, the following insights were gained: 1) Limiting the supply air area of the induction unit to a specific height and supplying conditioned air from the corners of the room can achieve displacement ventilation; 2) The impact of cubicle curtains around the bed on the effectiveness of displacement ventilation was evaluated; 3) The influence of outdoor temperature on the stability of displacement ventilation was elucidated, and strategies to improve its effectiveness during the heating period were examined.