An Analysis of Air Conditioning System Operation Patterns on Droplet Particle Distribution in a Classroom-A CFD Approach

In the classroom context, the transmission of pathogens among students is a significant concern. Therefore, it is important to determine appropriate airflow patterns, the placement of supply and exhaust ventilation, and the optimization of classroom design to reduce the risk of pathogen transmission. This research aims to determine the performance of two air conditioning (AC) operating patterns—low speed and high speed—in six scenarios involving window and door configurations and identify the most effective strategies for minimizing virus exposure to occupants in classrooms. The method used in this research is numerical simulation with the 3D unsteady k-ε RNG model to simulate air flow and the Eulerian-Lagrange approach to capture the movement of SARS-CoV-2 aerosol droplets. The results of this research show that of the six scenarios determined by the researchers, the low-speed AC operating pattern with an incoming air speed of 3.5 m/s occurs in scenario 5, that is, all windows open and doors closed. This is based on the lowest number of students exposed to the virus, which is 22.22%. Meanwhile, the high-speed AC operating pattern with an incoming air speed of 6 m/s occurs in scenario 2, that is, all windows closed and doors open. This is based on the lowest number of students exposed to the virus, which is 22.22%, so it can be concluded that increasing the air flow speed originating from the AC will speed up the droplets to leave the room through the outlet. Meanwhile, increasing the outlet capacity will shorten the particle path, thereby shortening the time when the droplets are in the classroom.