Development of advanced natural gas fueling strategies

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Natural gas fueling for heavy-duty engines offers a near-term path to meaningful reductions in greenhouse gas (GHG) emissions from on-road freight transport. Tailpipe CO2 emission reductions on the order of 20% relative to equivalent diesel are achievable. Adding renewable natural gas (RNG) to the fuel offers significant fuel-cycle benefits without requiring further modifications to the engine. However, unburned CH4 emissions are problematic and erode the GHG benefits of NG fueled engines. Lower CH4 emissions need to be met within the competing demands of increasing fuel efficiency requirements and lower tailpipe emissions, in particular anticipated further reductions in tailpipe NOx emissions. At the same time, the engines must be cost-competitive with incumbent technologies, matching performance with an acceptable payback period for incremental costs. Of the NG engine technologies to meet these challenges, pilot-ignited compression ignition engines offer a promising pathway, but still face challenges. The work proposed herein will develop and evaluate technologies for direct injection NG engines to: 1) identify routes to reduce engine-out NOx emissions to meet future ultra-low NOx emissions standards; 2) reduce the fuel system complexity by eliminating or minimizing the need for a pilot injection, and; 3) identify the mechanisms responsible for CH4 emissions. A single cylinder research engine at UBC will be utilized to identify new operating strategies and to characterize the associated combustion process, efficiency, and emissions. In addition,an optically accessible single cylinder engine will be used for characterizing the in-cylinder processes. This five-year project will train six HQP, who will build skills in the areas of: energy systems, combustion, air quality, instrumentation, image processing, and data analysis. The improvements in direct injected NG engines will benefit Canada by facilitating the use of a domestically abundant fuel, ultimately resulting in lower, NOx, particulate, and GHG emissions.**