Abstract：
Polyoxymethylene dimethyl ether (PODE) and methanol are important low-carbon substitutable fuels for reducing carbon emissions in internal combustion engines. In the research, the impacts of methanol ratio, injection timing, and intake temperature on HCHO generation and emission were investigated using both engine tests and numerical simulations. Results suggest that an increase in methanol ratio suppresses auto-ignition tendency of PODE, leading to the increase of ignition delay period, pressure peak, and heat release rate peak inside the cylinder. The decrease in in-cylinder combustion temperature contributes to an increase in HCHO emission due to partial oxidation of methanol in the cylinder and exhaust pipe. While the injection timing is gradually postponed from -10 °CA ATDC to 2 °CA ATDC, in-cylinder high-temperature area decreases, the quantity of unburned methanol increases, but part of HCHO is converted to HCO due to H radical influence, resulting in 72% increased HCHO emission. With the increment of intake temperature, the oxidation and decomposition of in-cylinder methanol accelerate, leading to an improvement in combustion stability, more uniform temperature distribution, and a decrease in unburned methanol, which results in lower HCHO emission. When the intake temperature is rose from 30 to 60 °C, HCHO emission decreases by 11.2%.
摘要：
聚甲醛二甲醚（PODE）和甲醇是重要的低碳替代燃料，可降低内燃机的碳排放。在研究中,甲醇比的影响，喷射正时,利用发动机试验和数值模拟研究了进气温度对HCHO生成和排放的影响。结果表明，甲醇比例的增加抑制了PODE的自燃趋势，导致点火延迟时间的增加，压力峰值,和气缸内的放热率峰值。缸内燃烧温度的降低有助于由于缸内和排气管中的甲醇的部分氧化而导致的HCHO排放的增加。当喷射正时从-10°CAATDC逐渐推迟到2°CAATDC时,缸内高温区域减少，未燃烧甲醇的数量增加，但是由于H自由基的影响，部分HCHO转化为HCO，导致HCHO排放增加72%。随着进气温度的升高,缸内甲醇的氧化和分解加速，导致燃烧稳定性的改善，更均匀的温度分布，减少未燃烧的甲醇，这导致较低的HCHO排放。当进气温度从30℃上升到60℃时，HCHO排放量减少11.2%。
