Optimum Seat Cooling Distribution for Targeted Human Thermal Comfort®

Seat cooling and heating strategies have enhanced human thermal comfort in automotive environments. Cooling/heating strategies also need to focus on the distribution of the seat cooling/heating power across the seat and the effect of such distributions on human thermal comfort. This paper studies the effect of active cooling combined with ventilation only strategy on thermal comfort. As part of the study, heat flux between the occupant and seat is mapped and is correlated to a step increase in the occupant’s local thermal comfort of body segments in contact with seat. A human physiological model and the Berkeley comfort model were combined to determine power and optimum placement of cooling to effectively cool an occupant using a climate control seat in a warm environment. This leads to a new approach using asymmetric seat cooling to distribute cooling power resulting in improved and balanced subjective comfort than traditional climate seat and ventilation technologies. A computational model was developed and validated through chamber test results. The computational model can deliver temperature distribution and thermal sensation/comfort values for varied boundary conditions such as differing ambient temperatures, mass flow rates and temperatures of cooling air through seat. In this study, the thermal chamber and seat were soaked to 44^oC before running the test with the human seated. Active cooling was applied to seat back/lumbar area and ventilation only was applied to the seat cushion area. The occupants recorded their local contact segment sensation and comfort every two minutes. Temperatures for the seat and human as well as heat flux between them were measured every 1 second. The model temperatures correlated to within 1^oC of experiment. The computed local thermal sensation and comfort values were also correlated to those measured in the chamber.