Virtual Thermal Comfort Engineering

Simulation of passenger compartment climatic conditions is becoming increasingly important as a complement to wind tunnel and field testing to help achieve improved thermal comfort while reducing vehicle development time and cost. Delphi Harrison Thermal Systems has collaborated with the University of California, Berkeley to develop the capability of predicting occupant thermal comfort to support automotive climate control systems. At the core of this Virtual Thermal Comfort Engineering (VTCE) technique is a model of the human thermal regulatory system based on Stolwijk’s model but with several enhancements. Our model uses 16 body segments and each segment is modeled as four body layers (core, muscle, fat, and skin tissues) and a clothing layer. The comfort model has the ability to predict local thermal comfort level of an occupant in a highly non-uniform thermal environment as a function of air temperature, surrounding surface temperatures, air velocity, humidity, direct solar flux, as well as the level of activity and clothing type of each individual. VTCE takes into account the geometrical configuration of the passenger compartment including glazing surfaces, pertinent physical and thermal properties of the enclosure with particular emphasis on glass properties. Use of Virtual Thermal Comfort Engineering (VTCE) will allow for exploration of different climate control strategies as they relate to human thermal comfort in a quick and inexpensive manner.