UBC Theses and Dissertations
The application of exhaust gas recirculation to a single cylinder compression ignition engine fuelled with natural gas McTaggart-Cowan, Gordon
Reducing the emissions of Nitric Oxides from diesel engines is one of the main challenges facing diesel engine designers. Many different methods have been investigated for reducing NO₂ emissions, including exhaust gas recirculation (EGR) and the high pressure direct injection (HPDI) of natural gas. Combining these two techniques offers the potential to reduce NO₂ emissions further than either method can individually. To test the effects of EGR on an HPDI engine, the University of British Columbia's Alternate Fuels Research Group recently received a new Cummins ISX heavy-duty truck engine, modified for single-cylinder operation. The new engine was commissioned on HPDI and a series of tests were run to compare its performance and emissions to a six-cylinder HPDI engine. These results showed good agreement for performance, but some significant differences in emissions between the two engines. Although emissions data are not directly transferable to a six-cylinder engine, the trends and general effects identified through testing on the single cylinder engine should be applicable to all HPDI engines. The new engine has also been used to study the combination of EGR and HPDI. While of a preliminary nature, the results indicate that significant NO₂ reductions can be achieved, with the greatest effects being found at low-speed, moderate-load operating conditions. Reductions in NO₂ emissions of as much as an order of magnitude were detected, but these extreme reductions came at the price of increased hydrocarbon emissions and reduced engine performance. More moderate reductions in NO₂ can be achieved with little penalty in either performance or emissions.
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