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In the United States, an intercity long-haul truck averages approximately 1,800 hrs per year for idling, primarily for sleeper cab hotel loads, consuming 838 million gallons of diesel fuel across the entire long-haul fleet [1]. Including workday idling, over 2 billion gallons of fuel are used annually for truck idling [2]. The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) is working on solutions to reduce idling fuel use through the CoolCab project. The objective of the CoolCab project is to work closely with industry to design efficient thermal management systems for long-haul trucks that minimize engine idling and fuel use while maintaining the cab occupant comfort. NREL conducted an experimental test program at their Vehicle Testing and Integration Facility in collaboration with Volvo Trucks, Aearo Technologies LLC / E-A-R Thermal Acoustic Systems - a 3M company, 3M Corporation, and Dometic Environmental Corporation.

The objective of this work was to synthesize the time and space average operating airborne noise excitation field from discrete noise sources, to the exterior surfaces of a Class 8 truck cab while operating fully loaded at 60 mph. This noise field was subsequently used as input to a statistical energy analysis (SEA) model, for designing a sound package to reduce interior noise. As a relatively simple and inexpensive alternative approach to direct measurements using a heavy-duty chassis dynamometer in a semi-anechoic chamber, the method nevertheless provided an acceptable input for the SEA development work.

Statistical Energy Analysis (SEA) was used during the design of a new heavy duty truck. This paper provides an overview of the building and validation process of an airborne SEA model of a typical commercial vehicle. Predictions of interior noise levels are compared against tests. A noise path contribution analysis is presented, demonstrating how the impact of potential design changes on the interior sound levels can be evaluated with an SEA model.