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As part of a California Selective Catalyst Reduction (SCR) system demonstration and evaluation project [13], the authors and their industrial partners have conducted engine dynamometer emissions tests of SCR systems. The transient Federal Test Procedure (FTP) cycle and 13 Mode European Stationary Cycle (ESC) were conducted using certification diesel fuel with 300-500 ppm of sulfur. This paper reviews the performance of the first system to meet the goal of attaining 1 g/bhp-hr NOx emissions in the transient FTP cycle on a 1999 DDC Series 60 engine that has an initial 4 g/bhp-hr level. This paper discusses key characteristics of a typical automotive SCR system and then presents the results and analysis of the engine dynamometer emission testing of a SCR system. The paper concludes with a discussion of the challenges involved in on-road operation of the system.

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.

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.

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.