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In recent years emission control agencies have turned their attention to to the cleanup of diesel engines, both mobile and stationary. This paper is one of the first attempts to characterize the load and emissions of a subsection of stationary diesel emissions, specifically Truck/Trailer Refrigeration Units (TRUs). These devices are used to keep refrigerated or frozen cargo cold when it is being shipped/delivered. Two general sizes of TRUs were tested, smaller TRUs for cooling box trucks, used for local deliveries, and large TRUs, used for long hauling and very large deliveries. After observing a matrix of these units over a large spectrum of temperatures it was found that, although there were multiple control strategies, they all heavily relied on pulling the trailer down to the set point temperature as fast as the engine and refrigeration unit would allow.

Recently public agencies have been promulgating idling bans in an effort to mitigate the environmental effects of heavy-duty truck idling. In order to make rational choices, regulators, manufacturers, and consumers will need to compare idling reduction strategies, such as truck stop electrification and auxiliary power units. Truck driver behaviors, such as idling time, idling location, and accessory use will significantly influence the cost-effectiveness of the various technology options. Truck driver attitudes toward idling and idling alternatives will influence adoption of the technologies. A pilot survey of 233 line-haul truck drivers was administered in Northern California as the first step in assessing truck driver behaviors and attitudes related to idling. Initial findings reveal that line-haul truck drivers idle primarily to power climate control.

In the last five years, there have been multiple demonstrations of fuel cell auxiliary power units (APUs) which provide power in lieu of idling of the main vehicle engine. The Institute of Transportation Studies at the University of California Davis has designed and evaluated a retrofitted, proton exchange membrane (PEM) fuel cell APU for powering accessories in heavy-duty truck cabs. The performance objectives for the system were determined based on truck driver feedback and industry design guidelines. The final FC APU system was developed to run for 3 days between refueling at a power output of 1.8 kW. The primary goals were to utilize exclusively commercially available components and to minimize costs. This paper discusses the performance targets, design tradeoffs, and evaluation of the developed system.