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As part of an ongoing program to control the emissions of diesel-powered equipment used in underground mines, the U. S. Bureau of Mines evaluated exhaust emissions from a compression ignition engine using oxygenated diesel fuels and a diesel oxidation catalyst (DOC). The fuels include neat (100%) soy methyl ester (SME), and a blend of 30% SME (by volume) with 70% petroleum diesel fuel. A Caterpillar 3304 PCNA engine was tested for approximately 50 hours on each fuel. Compared with commercial low-sulfur diesel fuel (D2), neat SME increased volatile organic diesel particulate matter (DPM) but greatly decreased non-volatile DPM, for a net decrease in total DPM. The DOC further reduced volatile and total DPM NOx emissions were slightly reduced for the case of neat SME, but otherwise were not significantly affected. Peak brake power decreased 9% and brake specific fuel consumption increased 13 to 14% for the neat methyl soyate because of its lower energy content compared with D2.

The Bureau of Mines, U.S. Department of the Interior, conducts research to reduce exposure of miners to exhaust emissions of diesel-powered mining equipment. Conventional sampling and instrumentation techniques used to measure emissions over a research duty cycle distort the signal generated by time variation of the concentration of gases in the exhaust. Delays up to 30 sec, effective integration times up to 2.9 sec, and dispersions up to 1.4 sec are observed. This paper reports numerical techniques that make it possible to infer the actual variation of concentration in the exhaust on a time scale of about 1 sec. These techniques are used to evaluate the product of concentration and flow to yield accurate total gaseous emission during a test.