Effects of PODE/diesel blends on particulate matter emission and particle oxidation characteristics of a common-rail diesel engine

The current study focused on the particulate matter emissions of polyoxymethylene dimethyl ethers (PODE)/diesel blends with PODE blending ratios of 0, 10%, 20% and 30% have been experimentally investigated in a common-rail engine. The influences of PODE blending ratio on the smoke emission, particle size distribution and particle oxidation characteristic are discussed. Results show that the addition of PODE in diesel fuel can effectively reduce smoke emission and its decreasing range becomes larger with increasing PODE blending ratio. With the increment in PODE blending ratio, the particle concentration distribution moves towards the direction of small particle size, and the total particle number concentrations decrease. Besides, the peak values of particle number concentration, surface area concentration, and volume concentration are all decreased. Adding PODE in diesel fuel increases the soluble organic fraction (SOF) content of particles, rises maximum weight loss rate of particles, and lower the peak temperature of particles. Also, the activation energy of pyrolysis reaction of particles decreases, which indicates that the oxidation of particles becomes easier as PODE blending ratio increases. The apparent morphology of particles was measured by scanning electron microscope, and the results show that the morphology of particles sample are mostly chain like or flocculent.