Assessment of Various Environmental Thermal Loads on Passenger Compartment Soak and Cool-down Analyses

Energy efficient HVAC system is becoming increasingly important as the higher Corporate Average Fuel Economy (CAFE) standards are required for future vehicle products. The present study is a preliminary investigation which addresses an energy efficient HVAC system without compromising occupant thermal comfort. The vehicle cabin is subjected to various thermal environments. Thermal analysis of a passenger compartment involves not only the geometric complexity but also strong interactions between airflows and three modes of heat transfer, namely, heat conduction, convection, and thermal radiation. The present full 3-D CFD analysis takes into account the geometrical configuration of the passenger compartment including glazing surfaces and pertinent physical and thermal properties of the enclosure with particular emphasis on glass properties. Many of the design parameters related with the climate control system are dependent on each other and the relationship among them is quite complex.. The present sensitivity analyses for hot soak and cool-down events demonstrate the sensitivity of various vehicle cabin thermal environments, including glass properties, vehicle body insulation, and vehicle interior thermal mass for a compact size vehicle. The combination of the present CFD work and the potential thermal comfort simulations of our future studies will shed lights on climate control strategies as they relate to human thermal comfort for an “Energy Efficient HVAC System”.