Numerical simulations on the effects of using ventilation fan on conditions of air inside a car passenger compartment

Abstract

The use of a mechanical ventilation fan is one strategy that can be employed to reduce high air temperature build up in a car passenger compartment when it is parked in the sun. This study developed a numerical simulation to investigate the effects of using a ventilation fan on the air temperature inside the passenger compartment when it is parked in the open space during a sunny day. A computational fluid dynamics (CFD) method was used to perform the numerical simulations. FLUENT software was employed to develop the passenger compartment model and simulate the air flow conditions inside the passenger compartment. The validation of the numerical simulation was done by comparing the air temperatures from the CFD simulation results against the air temperatures at two selected points obtained from the field measurement from 12 pm to 3 pm. On average, the air temperature prediction at the front and rear compartment show good agreement with the measured data, with a difference of about 2.5% and 1.6%, respectively. The validated numerical simulation was used to perform a parametric study to investigate the effects of the ventilation fan location, number of the ventilation fans as well as the air velocity at the ventilation fans, on the air temperature and air flow pattern inside the passenger compartment. A threedimensional (3D) steady-state simulation results show that placing one ventilation fan at the rear deck with an air velocity of 2.84 m/s reduces the air temperature at the front and rear compartment by 4°C. Placing four ventilation fans at the roof lowers the air temperatures at the front and rear compartments by 6°C and 7°C, respectively. Increasing the air velocity from 2.84 m/s to 15.67 m/s at four ventilation fans placed at the roof suggests the highest reduction of the air temperature inside the passenger compartment by 8°C.