Effect of diglyme on diesel engine combustion and un/regulated emission

The influence of diglyme on diesel engine combustion and emission, including regulated and unregulated emissions, was carried out at various engine modes, in which ultra-low sulfur diesel and diglyme were employed, and diesel-diglyme blends were designed containing specific mass oxygen content varied from 2% to 20% corresponding to 5% to 53% diglyme blended by volume. With the addition of diglyme, actual air/fuel ratio decreased in general, combustion initiated earlier by 5.3% to 14.6% at tested modes but weighted center postponed with short ignition delay and combustion duration, meanwhile maximum in-cylinder combustion temperature reduced by 3 to 30°C, which affected emissions significantly.Consequently, the optimized PM-NOx trade-off was obtained with particulate and NOx decreased simultaneously, but formaldehyde and acetaldehyde increased by the varation from 3% to 190% with the addition of diglyme. Sulfur dioxide emission was much lower with ultra-low sulfur diesel compared that with other fuels including conventional diesel, about one order of magnitude smaller, and diglyme could bring further reduction by maximum of 62.5%. In addition, the oxygen in diglyme promoted CO oxidation and NO2 conversion from NO, leading to an increased NO2/CO ratio by even to 375.9%.