The electrification of accessories using a fuel cell as an auxiliary power unit reduces the load on the engine and provides opportunities to increase propulsion performance or reduce engine displacement. The SunLine™ Class 8 tractor electric accessory integration project is a United States Army National Automotive Center (NAC™) initiative in partnership with Cummins Inc., Dynetek™ Industries Ltd., General Dynamics C4 Systems, Acumentrics™ Corporation, Michelin North America, Engineered Machine Products (EMP™), Peterbilt™ Motors Company, Modine™ Manufacturing and Masterflux™. Southwest Research Institute is the technical integration contractor to SunLine™ Services Group.
In this paper the SunLine™ tractor electric Air Conditioning (AC) system is described and the installation of components on the tractor is illustrated. The AC system has been designed to retrofit into an existing automotive system and every effort was made to maintain OEM components whenever modifications were made. Hardware modifications were limited to replacing the engine driven compressor for a 42 volt DC driven one, exchanging the expansion orifice for a thermal expansion valve and positioning the components to minimize the length of refrigerant lines.
The thermodynamics and PID control algorithms are discussed. Closed loop test results are presented in controlled ambient conditions. Analysis of reversed Carnot cycle changes due to transient operation and coefficient of performance changes are given.