A Simulation Methodology for the Numerical Determination of the Equivalent Temperature

Similar to common experimental approaches, a numerical method to evaluate thermal comfort in the vehicle cabin is developed. According to ISO 14505-2:2006-12, thermal comfort is mainly influenced by the heat transfer phenomena of convection and radiation and also by complex flow mechanical conditions in the cabin. First, the method for a numerical solution procedure and the modeling of radiation is selected in the open source CFD-tool OpenFOAM. In order to validate the chosen solver, simple 1D and 2D simulations in the field of heat transfer are investigated and analyzed. As the results of these analyzes are within expectations of accuracy, the application of numerical methods can be used for more complex simulations of the vehicle cabin. For this purpose, a thermal sensor is calibrated, to models the heat exchange between the human body and the ambient environment. The calibration allows the determination of the equivalent temperature as well as the evaluation of thermal comfort based on Nilsson's ‘Comfort Zone Diagrams’. Finally, as part of the validation of the simulation methodology, the thermal comfort is determined for summer mode with a climate dummy in a climate test station. A good correlation between the numerical model and the measurement values is attained.