The climate inside a vehicle cabin is affected by the performance of the vehicle HVAC system, the thermal characteristics of the vehicle structure and the components, as well as the external environmental conditions. Due to the complex interactions among these various factors, the flow field and the temperature distribution can be very complicated. The need for a fully three-dimensional transient analysis is increasing in order to provide sufficiently detailed information that can be used to improve the vehicle design.
In this study, a numerical simulation methodology to predict the local climate conditions in a passenger vehicle cabin is presented. The convective heat transfer from both the exterior and the interior of the cabin were calculated by three dimensional CFD simulations using a Lattice-Boltzmann method based flow solver. The conduction and the radiation effects including the solar loading were solved using a finite-difference based radiation-conduction thermal solver. The coupling strategy between the two solvers was optimized in order to achieve a good balance between the desired solution accuracy and the simulation turn-around time.
The air and wall temperature distributions calculated by the simulation methodology are compared with available climatic wind tunnel data measured for a C-segment passenger vehicle undergoing a pre-defined test cycle. The comparison shows a good agreement and also demonstrates the potential of the simulation methodology as a useful tool in the vehicle HVAC design/engineering process.