Simulation of flow fields in the occupant compartment and analysis of occupant thermal comfort

To address the challenge of uneven thermal comfort among multiple occupants in vehicle cabins under extreme summer heat, this study developed a high-fidelity 1:1 vehicle model using Computational Fluid Dynamics (CFD). Following experimental validation with an error margin below 10%, the interaction effects of supply air angle, temperature, and velocity on the local and global thermal comfort of four occupants (driver and three passengers) were systematically investigated. Single-factor analysis revealed that conventional parameter settings often lead to localized overcooling or significant thermal disparities, with the supply air angle playing a decisive role in front-row comfort. Consequently, this study innovatively employed the Central Composite Design (CCD) within the Response Surface Methodology to construct a predictive model targeting the Total Equivalent Temperature (TEQ). The optimal parameter combination to minimize spatial thermal asymmetry and bound all occupants within the ideal thermal comfort zone was identified as: air angle A s = −76.18°, temperature T s = 17.31°C, and velocity V s = 5.56 m/s. The results demonstrate that the proposed joint CFD-Response Surface Methodology provides a mature, scalable, and highly efficient evaluation framework for automotive climate control under diverse thermal environments. This optimization effectively minimizes temperature deviation and ensures all occupants remain within the ideal thermal comfort zone, providing a scientific foundation for precision airflow design and intelligent climate control in automotive systems.