Fig. 1 Schematic presentation of the 30 m3 SARS-CoV-2 test room.
A venturi injector was used to mix the aerosolized virus into the air with an airflow rate of 12 L/min via a compressor to deliver the mixture to the test room for 20 minutes. The aerosolized virus was delivered into the 30 m3 test room through a leakproof plastic pipeline controlled with a ball valve. In the meantime, the fan was operated to ensure airborne virus homogenization. The humidifier fixed the humidity of the test room to 40%, and the air conditioning system set the temperature of the test room to 20\(\mp 1\) oC before turning the heater on.
A schematic presentation of the electric heater used in the experiments is given in Fig. 3. The electric heater consists of a fan and stainless steel electric tube heating elements. The fan draws the air inside the air tunnel. While the air passing through the heater gains heat energy by interacting with the heating elements located perpendicularly to the airflow direction, increasing the outlet air temperature of the heater within a few seconds.