Reactivity controlled compression ignition (RCCI) and homogeneous charge compression ignition (HCCI) are suitable alternatives to improve the performance and emission metrics of conventional diesel combustion. Previous studies have shown that the gasoline/diesel RCCI outperforms diesel HCCI as it has a wider load range, higher brake thermal efficiency, and lower smoke and oxides of nitrogen emissions. The present work addressed the shortcomings of diesel HCCI by replacing diesel with low reactivity, high volatile methanol–gasoline blends. 2-ethylhexyl nitrate, an ignition quality improver, was added in small amounts (6 vol.%) to the blends to avoid misfiring, particularly at lower loads. There were two approaches to improve engine performance metrics of methanol–gasoline HCCI: exhaust gas recirculation and fuel composition variation. The best approach was chosen, and HCCI performed using the selected approach was compared with baseline RCCI. The methanol-gasoline HCCI was compared to baseline-optimized gasoline/diesel RCCI to demonstrate that the challenges associated with diesel HCCI can be overcome through fuel modifications. It was revealed that the strategy of varying methanol concentration in fuel blends was more effective than the strategy of varying EGR rate in terms of efficiency improvement and reduction of soot, carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions. The parametric investigation showed that HCCI outperformed RCCI at mid to higher loads. For instance: at 60% load (3.19 BMEP), indicated thermal efficiency decreased by 7%, specific CO, UHC, nitrogen oxides, and smoke emissions elevated by 1.3, 1.2, 2.5, and 20.5 times for baseline-optimized RCCI than 40% methanol/54% gasoline/6% 2-EHN HCCI. Also, increased methanol in fuel during HCCI improved indicated thermal efficiency at a particular load. For instance, at 60% load, the indicated thermal efficiency improved by 30% during HCCI of fuel containing 40% methanol than 20% methanol. Overall, the present work discusses a practical method to efficiently use renewable methanol fuel in HCCI engines.

反应性控制压缩点火 (RCCI) 和均质充量压缩点火 (HCCI) 是改进传统柴油机燃烧性能和排放指标的合适替代方案。先前的研究表明，汽油/柴油 RCCI 优于柴油 HCCI，因为它具有更宽的负载范围、更高的制动热效率以及更低的烟雾和氮氧化物排放。目前的工作通过用低反应性、高挥发性的甲醇-汽油混合物代替柴油来解决柴油 HCCI 的缺点。将少量 (6 vol.%) 的硝酸 2-乙基己酯（一种点火质量改进剂）添加到混合物中以避免失火，尤其是在较低负载时。有两种方法可以改善甲醇-汽油 HCCI 的发动机性能指标：废气再循环和燃料成分变化。选择最佳方法，并将使用所选方法执行的 HCCI 与基线 RCCI 进行比较。将甲醇-汽油 HCCI 与基线优化的汽油/柴油 RCCI 进行比较，以证明与柴油 HCCI 相关的挑战可以通过燃料改进来克服。据透露，在提高效率和减少烟尘、一氧化碳 (CO) 和未燃碳氢化合物 (UHC) 排放方面，改变混合燃料中甲醇浓度的策略比改变 EGR 率的策略更有效。参数研究表明，HCCI 在中高负载下的性能优于 RCCI。例如：在 60% 负载 (3.19 BMEP) 时，指示热效率降低 7%，特定 CO、UHC、氮氧化物和烟雾排放量分别升高 1.3、1.2、2.5 和 20。基线优化的 RCCI 是 40% 甲醇/54% 汽油/6% 2-EHN HCCI 的 5 倍。此外，在 HCCI 期间增加燃料中的甲醇提高了特定负载下的指示热效率。例如，在 60% 负载下，含 40% 甲醇的燃料在 HCCI 期间的指示热效率比含 20% 甲醇的燃料提高了 30%。总的来说，目前的工作讨论了一种在 HCCI 发动机中有效使用可再生甲醇燃料的实用方法。