Abstract
By simulating the conditions of bed-laid patients in a biological clean room, experiments are carried out in order to study the airflows around the patients when horizontal commutation aseptic laminar flow units are operated at an airflow velocity of 0.3 or 0.5 m/s. When a patient is absent from the room, the airflows show a higher capability to transfer and remove particles at an airflow velocity of 0.5 m/s compared to that at 0.3 m/s. However, when a patient is present in the room, the airflows have a lower air exchange rate at an airflow velocity of 0.5 m/s than 0.3 m/s. This is because turbulent flow occurs downstream of the patient. The present results suggest that an increase in airflow velocity does not necessarily lead to an increase in ventilation because the wake size downstream of the patient increases with the airflow velocity.
