Transmission of micron-size droplets inside an air-conditioned sports-utility-vehicle: a numerical study

• Published in: HVAC&R research Vol. 30; no. 10; pp. 1268 - 1285
• Main Authors: Sen, Nirvik, Singh, K.K., Patwardhan, A.W.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 25-11-2024; Taylor & Francis Ltd
• Subjects: Air conditioners; Droplets; Exhalation; Infections; Risk management; Turbulence models; Vents
• ISSN: 2374-4731; 2374-474X
• DOI: 10.1080/23744731.2024.2366133

A 3D Euler-Lagrangian CFD model to simulate dispersion of micron-sized droplets (generated by coughing action) within a three-row air-conditioned sports-utility-vehicle is reported. The model is first validated against experimental data on droplet evaporation and flow field in an enclosure. Three turbulence models are compared. The study explores four sets of practical scenarios. First, varying air velocities from dashboard AC ports affect droplet dispersion, with higher velocities resulting in increased dispersion. For instance, at 3 m/s and 2 m/s, the percentage of particles falling on exposed surfaces is 93% and 36%, respectively. The second set investigates the impact of passenger seating arrangements (back-to-back and staggered). Staggered seating demonstrates a lower infection spread probability (0%) compared to back-to-back seating (20%). The third set examines the position of cough droplet exhalation, revealing that events in the rear (3rd) row pose the least risk (0% infection spread probability), while those initiated in the front (1st) row present the highest risk (60% infection spread probability). Finally, the fourth set assesses the influence of additional AC vents toward the rear of the vehicle, demonstrating a risk reduction from 60% to 20% infection spread probability when such vents are present.