Comparison study on the emission characteristics of diesel- and dimethyl ether-originated particulate matters

Abstract

Smoke-free property of dimethyl ether (DME) was utilized to eliminate the influence of fuel on PM formation. The particulate matter (PM) emission characteristics, including mass emission, number concentration distribution, morphology and the percentage composition of soluble organic fraction, were experimentally studied on a compression ignition engine when it ran on diesel and DME, respectively. The emission characteristics were compared and analyzed to better understand the commons and differences of between fuel and lubricant oil originated PM emissions.Experimental results show that, the number concentrations of DME and diesel engine-out PM emissions both decrease with the engine speed, and increase with engine load; the volumetric mass emission of diesel engine-out PM coincides well with its number emission. However, the volumetric mass emission of DME engine-out PM increases with engine speed and performs typical production–consumption effect with the increasing factor of Ttq⋅en. The diesel engine-out PM emission was composed on average of 84% of non-volatile fractions of soot and sulfates and 16% of soluble organic fractions (SOFs) with about 9% of which originated from diesel fuel and 6.8% from lubricant oil. Less lubricant oil originating products such as SOF and soot were emitted on DME engine than on diesel engine.