Evaluation of Equivalent Temperature in a Vehicle Cabin with a Numerical Thermal Manikin (Part 1): Measurement of Equivalent Temperature in a Vehicle Cabin and Development of a Numerical Thermal Manikin 2019-01-0697

The present paper is Part 1 of two consecutive studies. Part 1 describes three subjects: definition of the equivalent temperature (t_eq), measurements of t_eq using a clothed thermal manikin in a vehicle cabin, and modeling of the clothed thermal manikin for t_eq simulation. After defining t_eq, a method for measuring t_eq with a clothed thermal manikin was examined. Two techniques were proposed in this study: the definition of “the total heat transfer coefficient between the skin surface and the environment in a standard environment (h_cal)” based on the thermal insulation of clothing (I_cl), and a method of measuring I_cl in consideration of the area factor (f_cl), which indicates the ratio of the clothing surface to the manikin surface area. Then, t_eq was measured in an actual vehicle cabin by the proposed method under two conditions: a summer cooling condition with solar radiation and a winter heating condition without solar radiation. The results showed that t_eq, including the effects of the air temperature, air velocity and thermal radiation, was measured properly. Subsequently, a numerical thermal manikin was developed. The geometry of the clothed manikin was modeled by 3D laser scanning. The procedure for evaluating t_eq using the numerical thermal manikin was defined, based on a heat exchange model in consideration of the f_cl effect. The evaluation procedure can be applied to all manikin control modes described in ISO 14505-2, namely, a constant temperature mode, a constant heat flux mode and a comfort equation mode. Finally, the calculation accuracy obtained with the numerical thermal manikin was confirmed under a uniform environment. The results showed good agreement with the measured data. The numerical thermal manikin was used in a vehicle simulation in Part 2, and the simulation results were validated in comparison with the vehicle measurements made in the first part.