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Line-haul truck engines are frequently idled to power hotel loads (i.e. heating, air conditioning, and lighting) during rest periods. Comfortable cabin climate conditions are required in order for mandatory driver rests periods to effectively enhance safety; however, the main diesel engine is an inefficient source of power for this conditioning. During idle, the diesel engine operates at less than 10% efficiency, consuming excess diesel fuel, generating emissions, and accelerating engine wear. One promising alternative is the use of small auxiliary power units (APUs), particularly fuel cell-based APUs. The Institute of Transportation Studies (ITS-Davis) developed an ADVanced VehIcle SimulatOR (ADVISOR)-based model to quantify the costs and benefits of truck fuel cell APUs. Differences in accessories, power electronics, and control strategy between the conventional engine idling and APUequipped systems are analyzed and incorporated into the model.

This paper presents model-based predictions of the performance of diesel, compressed natural gas (CNG), and hybrid buses on bus routes in the City of San Francisco. The bus route details were obtained by recording time-series measurements of speed and grade during actual runs of buses on the city streets under different traffic conditions. The transit buses' physical and mechanical characteristics were obtained from manufacturers' data and chassis dynamometer testing of the buses on different city cycles. Both the bus routes and the bus performance characteristics were put into the simulation package ADVISOR from the National Renewal Energy Laboratory (NREL). The most extreme results were for the San Francisco routes that have high grades. The high grades cause performance and emissions problems for both the diesel and CNG buses relative to the hybrid bus.

A novel ambient dilution tunnel has been designed, tested and employed to measure the emissions from active parked regenerations of Diesel Particulate Filters (DPFs) for 2007 and 2010 certified heavy duty diesel trucks (HDDTs). The 2007 certified engine had greater regulated emissions than the 2010 certified engine. For a fully loaded 2007 DPF there was an initial period of very large mass emissions, which was then followed by very large number of small particle emissions. The Particle Size Distribution, PSD, was distributed over a large range from 10 nm to 10 μm. The parked regenerations of the 2010 DPF had a much lower initial emission pattern, but the second phase of large numbers of small particles was very similar to the 2007 DPF. The emission results during regeneration have been compared to total emissions from recent engine dynamometer testing of 2007 and 2010 DPFs, and they are much larger.