Numerical simulation study of the combustion characteristics of high compression ratio DISI methanol engine based on orthogonal experimental design

A combination of numerical modeling and orthogonal tests was used to analyze the effects of the start of injection (SOI), spark timing (ST), intake temperature ( T int ), methanol temperature ( T met ) and spark plug distribution ( Lsp ) on the combustion, energy distribution, noise and emission characteristics of a high-compression-ratio (17.3) direct-injection spark-ignition (DISI) methanol engine. The results indicate that SOI, ST, and T int have the most significant effects on the performance and emissions of the DISI methanol engine, with T met and Lsp being more subordinate. By optimizing the parameter combinations, the indicated thermal efficiency (ITE) and ringing intensity (RI) are 47.27 % and 5.02 MW/m 2 , respectively, under the best parameter combinations. Although the ITE is comparable to the maximum ITE of the orthogonal test (47.28 %), the maximum peak pressure rise ( M PPR ) and RI have decreased by 22.39 % and 36.17 %, respectively. Compared to the experimental parameters, the parameter-optimized ITE has increased by 4.21 %, while the heat transfer loss, M PPR and RI have decreased by 23.64 %, 47.47 % and 70.18 %, respectively. Although the decrease of the T int prevents further oxidation of UM and HC, and it has increased by 12.06 % and 10.92 %, respectively, NOx , CO, SOOT, and formaldehyde have decreased by 88.91 %, 20.67 %, 24.36 %, and 3.14 %, respectively.