Evaluating a Heavy-duty Truck Climate Control System using Thermal Comfort-focused Testing and Simulation Techniques 2019-01-0696
The design of efficient vehicle climate control systems involves reconciling two competing objectives: Maximizing the thermal comfort of occupants while simultaneously reducing the vehicle’s energy usage. Given the energy expenditure of traditional HVAC systems, efforts have been directed toward reducing their weight and power requirements. Consequently, vehicle manufacturers are increasingly investigating the use of thermal comfort as a design metric, rather than air temperature, which requires heating or cooling of the entire cabin air volume. Thermal comfort-focused technologies, such as localized heating and cooling strategies, have the potential to elicit favourable subjective responses to thermal environments even when the ambient air temperature in the cabin would otherwise fall outside of established acceptability guidelines. These technologies can be especially relevant for heavy-duty truck manufacturers since the cabin is relatively large, with an HVAC system sized accordingly, and often occupied by a single driver for long durations.
Thermal comfort-focused testing and simulation techniques previously employed for automobiles have been applied to scenarios involving heavy-duty trucks. A set of human subjects and a test system comprised of a high resolution passive sensor manikin and a human thermal model were used to evaluate the climate control system of a truck in terms of thermal comfort perception. The testing was performed within a climate controlled wind tunnel equipped with a dynamometer. The truck’s HVAC system performance was evaluated within a -10 °C ambient condition. Subjective responses, including thermal sensation and comfort, and thermo-physiological state information, quantified by skin temperatures measured across the body, were obtained from the human test participants and compared to those reported by the test system.
Mark Hepokoski, Steven Patterson, Allen Curran, Steven Adelman, Miguel Javier
ThermoAnalytics Inc., Volvo Trucks North America