In this study, the air flow through the complete HVAC system (Heating-Ventilation-Air-Conditioning system) together with the flow field in the passenger compartment of a new Mercedes is calculated using the commercial CFD program STAR-CD. Two operating conditions of the HVAC system have been considered, namely the standard winter heat-up and summer cool-down mode.
The computational model consists of around 6 million cells and includes all parts of the HVAC system (inlet plenum chamber, fan, filters, air distribution chamber with evaporator and heater, air ducts and vents) together with a detailed description of the passenger compartment containing four occupants.
The numerical results are used for the evaluation of different aspects related to the ventilation and air-conditioning of the car interior, e.g. air mass flux distribution to the different vents, ventilation of the frontal and rear legrooms, defrosting of the windscreen and the side windows, ventilation of the driver's side of the compartment in comparison to the passenger's side, thermal comfort of the occupants.