Enhancement of Efficiency and Thermal Comfort in a Passenger Car Cabin Using Spanwise Inlet Vents

Ensuring thermal comfort in car passenger cabins has been a sustained area of interest, both for automobile manufacturers and HVAC engineers alike. Towards this end, the four-channel inlet system appears to be the most common design among a majority of commercial vehicles. However, some recent studies indicate a lack of homogeneity due to flow transition with consequent effects on thermal distribution, leading to passenger dissatisfaction and discomfort. Thus, the current paper presents an alternative design for inlet vents of automobile passenger cabins for ensuring proper airflow and thermal distributions. The modified inlet design ensures a homogeneous circulation of air inside the car cabin, leading to reduced sensitization due to the localized cooling effect. The proposed ventilation design constitutes a high aspect ratio spanwise inlet vent that extends along the entire span of the dashboard. The computational simulations have been conducted using Fluent software package from ANSYS for the transient case and the resulting flow and thermal distributions are compared for ensuring thermal homogeneity as per ASHRAE standards for twelve pre-defined crucial locations in the passenger cabin. Our study indicates that the modified inlet vent design results in a faster temperature pull down, better flow homogeneity, and a greater heat recovery efficiency over the baseline design.