Numerical investigation on the combustion characteristics of PODE_3/ gasoline RCCI and high load extension

摘要

In this work, a numerical investigation was conducted to explore the combustion characteristics of poly-oxymethylene dimethyl ethers (PODE3)/gasoline Reactivity Controlled Compression Ignition (P/G RCCI) at high load. Firstly, the differences between P/G and Diesel/gasoline (D/G) RCCI are studied and the combustion process is analyzed under both medium and high load conditions. Then, the effects of premix ratio of gasoline (RP), exhaust gas recirculation (EGR) and PODE3 start of injection (PODE3 SOI) on combustion process are further analyzed and discussed. Results reveal that compared with diesel, PODE3 can improve the local equivalence ratio distribution and energy density distribution during the spray combustion process under both medium and high load conditions. Consequently, lower emissions, and higher indicated thermal efficiency (ITE) can be obtained without penalty in pressure rise rate (PRR) and maximum in-cylinder pressure (Pmax), which means that PODE3 has the potential for high load extension. In addition, it is found that lower Rp, together with less EGR and regarded injection timing can be beneficial for both the emission and PRR suppression at high load.