Emissions as functions of fuel oxygen and load from a premixed low-temperature combustion mode:

Soot, mono-nitrogen oxides (NOx), carbon monoxide (CO) and hydrocarbon emissions are investigated as functions of fuel oxygen and engine load in a single-cylinder diesel engine operated in a premixed low-temperature combustion mode by isolating fuel oxygen from other fuel properties and removing or minimizing variations in engine combustion parameters. It is found that at high loads (high global equivalence ratios), soot is reduced as fuel oxygen increases. Over the load range tested, CO and hydrocarbon emissions are not affected by fuel oxygen fraction. NOx emission increases as load is decreased because intake composition changes. NOx emission is not directly affected by fuel oxygen. The difference in NOx emission among the different oxygen fuels is indirectly caused by different exhaust composition affecting intake composition. Combustion efficiency and indicated thermal efficiency are similar for the test fuels with different oxygen fractions.