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UBC Theses and Dissertations

Measurement and characterization of in-use emissions from dual-fuel diesel engines operating on alternative fuels Guan, Mang


Alternative fuels such as hydrogen (H2), natural gas (NG), and biodiesel can be substitutes for diesel fuel in compression ignition engines. Dual-fuel combustion technology is an effective way to utilize gaseous fuels ignited by pilot liquid fuels in existing diesel engines with minor modifications. The effects of different fuels on engine emission especially under real-world operating conditions are important information for engine manufacturers as well as vehicle operators. For this reason, this study aims to evaluate the in-use emissions for CI engines operating on the alternative fuels. The first study focused on the unburned H2 emission from a heavy-duty truck equipped with a 15 L diesel engine retrofitted to run in dual-fuel mode with port-injected H2. A Portable Emission Measurement System (PEMS) was developed integrating a semi-conductor H2 sensor, which gives the H2 concentration in the exhaust stream. On-road emission tests were implemented on the truck with the PEMS to measure the in-use H2 emission under real-world operating conditions. H2 slip maps were generated using the concentration data. The work presented the methodology to use a low-cost sensor for in-use vehicle's exhaust H2 measurement. In the second study, in-use emission measurements were taken for a diesel/NG dual-fuel marine vessel. The emissions under diesel mode and dual-fuel (NG + pilot fuel) mode were considered with diesel (baseline), Soybean Methyl Ester (SME), and Canola Methyl Ester (CME). It was found that under diesel mode steady states, NOx emissions were increased by 21.6% on average by both biodiesels. Particle number (PN), particularly in the submicron range, were substantially increased by the biodiesels, likely an artefact of nucleation mode or volatile compounds. Under load increase conditions, transient CO and PM concentrations were substantially higher than the steady state results. Both biodiesels resulted in reduced PM emissions compared to diesel. Under dual-fuel mode, when used as the pilot fuel, SME and CME reduced NOx emissions by 14 .7% and 19. 7%, respectively. The results proved that biodiesels are a potential alternative fuel for heavy-duty marine engines, though some questions remain to be answered.

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