Study on the Thermal Accumulation and Distribution Inside a Parked Car Cabin

Problem statement: When a vehicle is parked under the direct sun, the accumulated heat is affecting many interiors inside the vehicle cabin, such as the vinyl materials of the dashboard, the leather covers and the electronic components. Also, it represents an uncomfortable operating period for the passengers. The studies under this topic are entitled by the vehicle manufacturers as "Vehicle Cabin Comfort". Approach: In the present study, experimental and numerical analyses were conducted. The experimental results were obtained from measurements on a salon car parked in unshaded area. Six different cases had been investigated consisting of full windows closing case, four different windows opening settings and sun shade usage case. The temperature at 12 different locations inside the car had been recorded for many days and the mean values are used as initial and boundary conditions to run the 3-D computational simulation. The CFD simulation was carried out by FLUENT software. Results: Both experimental and CFD simulation results revealed that the most hot air was accumulated in the top part of the cabin and natural circulation take place with large scale cavity due to natural heat transfer from the dashboard and the rear windshield. The drop down of the front side windows by 20 mm caused reduction in the front air gap by 20%. The sunshade on the front had considerably reduced the heat accumulation inside the cabin, where the dashboard surface temperature dropped by 26% and the maximum air temperature was found to be 27% lower. Conclusion: The use of the sunshade and/or dropdown windows on both sides reduced the heat accumulation due to fresh air exchange with the exterior environment.