Work

On the effect of HVAC recirculation on thermal comfort and indoor air quality in train cabins

Year: 2025

Type: article

Abstract: Maintaining hygrothermal comfort and Indoor Air Quality (IAQ) in train cabins is crucial for the well-being of passengers and crew, particularly in mitigating the risks associated with airborne transmission. The Heating, Ventilation, and Air Conditioning (HVAC) systems play a critical role in determining airflow patterns, thermal comfort indices, and the distribution of airborne particles. This study investigates the effects of varying return air intake ratios, a practical and non-structural modification, using Computational Fluid Dynamics (CFD). Four HVAC configurations with different return air percentages (0 %, 25 %, 50 %, and 75 %) are assessed in terms of thermal comfort indices and the particles evacuation efficiency generated by a sneeze. The results reveal an optimal trade-off between thermal comfort and particle evacuation efficiency: low return intake (0 %) provides the best thermal comfort conditions; however, the optimal IAQ is achieved with a moderate return intake (50 %), which results in the highest particle evacuation rate (82.34 %) and significantly reduced particle deposition in critical areas, such as the seating zones. In contrast, a high return air intake (75 %) leads to recirculation zones that trap particles and hinder their removal, while a low return air intake increases the risk of particle deposition for passengers. This study underscores the importance of a multi-criteria approach in HVAC design for train cabins, emphasizing that configurations optimized solely for comfort may not ensure protection against airborne pollutants. • HVAC intake ratio affects cabin comfort and air quality. • Lower return air improves thermal comfort significantly. • Moderate return intake (50 %) optimizes particle removal. • High recirculation rates increase particle deposition. • Adaptive HVAC control recommended for optimal results.

Source: Journal of Aerosol Science

DOI: 10.1016/j.jaerosci.2025.106720

Authors: Reza Hamidi Jahromi, Simona Di Fraia, Nicola Massarotti, Alessandro Mauro

Institutions: Parthenope University of Naples, University of Campania "Luigi Vanvitelli"

Language: English

Topic: Infection Control and Ventilation

Subfield: Pulmonary and Respiratory Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $2,850