Effect of polyoxymethylene dimethyl ethers on particle properties and diesel particulate filter regeneration

The emission tests were performed on a light-duty direct injection diesel engine. A polyoxymethylene dimethyl ethers (PODE) mixture was blended with diesel at a volume ratio of 0, 10, 20 and 30%, denoted as P0, P10, P20 and P30, respectively. The particle size distribution before and after the diesel particulate filter (DPF) was measured to evaluate the DPF filtering efficiency of various modal particles. The oxidation activity of the particles on the DPF intake end plane was analyzed by the Arrhenius method. The regeneration of the DPF was conducted using a non-thermal plasma (NTP) injection system. The results showed that blending PODE with diesel contributed to reducing the particle number concentrations. PODE adversely affected the improvement of the DPF filtering efficiency, especially that of P30. However, the DPF filtering efficiency of all fuels was still higher than 94%. Blending PODE with diesel increased the mass fraction of volatile substances (VS) and decreased the mass fraction of dry soot. Particles of P20 showed a better oxidation activity with lower apparent activation energy. In addition, PODE increased the DPF regeneration effect by NTP technology. The deposit removal mass of the DPF rose to the peak level and then decreased as the PODE blending ratio increased. The better DPF regeneration effect was observed when P20 was employed.