Experimental Verification of Use of Vacuum Insulating Material in Electric Vehicle Headliner to Reduce Thermal Load

Abstract

In electric vehicles (EVs), the use of high-temperature heat transfer components that effectively block external heat and minimize cooling losses can increase vehicle mileage during heating/cooling operations and improve passenger comfort. In particular, in ensuring high thermal insulation, the car headliner forms an important component for effectively managing environmental heat energy and heating and cooling processes inside the EV. In this study, we have proposed and experimentally verified the use and efficacy of vacuum insulation material in the headliner of EVs to reduce the heat load. The thermal conductivity and air permeability of various conventional insulating and vacuum insulation materials used for the headliner were compared to accurately predict the vacuum insulation material performance. We found that the vacuum insulation material affords reduced surface roughness and thermal conductivity and high formability relative to conventional insulation. We also confirmed consequent improvements in the insulation performance by comparing the characteristics of the proposed vacuum-insulation-material headliner (relative to conventional materials) via prototyping and reliability testing. With the “improved” headliner, in summer, the temperature of the automobile cabin was lowered by 2.8 °C, and the cabin temperature was lowered by 3.9 °C during the cooling period relative to conventional insulators, which proves that the cabin temperature can be maintained at a low value during summer parking or cooling. In winter, the cabin temperature was found to be 7.7 °C higher than that obtained with the conventional insulator, which indicates that the cabin temperature can be maintained higher via reduction in the heat loss (because of using vacuum insulation) under the same heating energy conditions during winter.