Numerical Study of Three Ventilation Strategies in a prefabricated COVID-19 inpatient ward.

ABSTRACT

Prefabricated inpatient wards have been proven to be an efficient alternative to quickly extend the caring capacity for patients. In this study, three typical ventilation strategies were studied using computational fluid dynamics in a prefabricated Coronavirus disease 2019 double-patient ward. Pollutants are the respiratory droplets and aerosols injected from two manikins. They are modelled as particles with different diameters (3 µm, 6 µm, 12 µm, 20 µm, 45 µm and 175 µm) by the Eulerian-Lagrangian model. Three ventilation strategies with an identical air change rate of 12.3 h-1 but different layouts of inlets and outlets are implemented. The flow field, flow structures and particle trajectories have been analysed and compared among the three ventilation strategies. The fate of particles is analysed and compared quantitatively. It is found that small particles (<20 µm) can move along with the main flow streams. Most of them are removed by ventilation to the outlet(s). Large particles (>45 µm) cannot move with the flow streams over a long path. Most of them deposit on solid surfaces in different regions of the ward in each ventilation strategy. Health workers should pay close attention to these polluted areas. Targeted cleaning of the polluted areas is necessary in a prefabricated inpatient ward. To promote the removal of some large particles (e.g., 45 µm) by the outlet(s), the outlet(s) should be installed inside the landing area of large particles and close to the polluted source(s).