Thanks to its properties and production pathways, ethanol represents a valuable alternative to fossil fuels, with potential benefits in terms of CO₂, NO_x, and soot emission reduction. The resistance to autoignition of ethanol necessitates an ignition trigger in compression-ignition engines for heavy-duty applications, which in the current study is a diesel pilot injection. The simultaneous direct injection of pure ethanol as main fuel and diesel as pilot fuel through separate injectors is experimentally investigated in a heavy-duty single cylinder engine at a low and a high load point. The influence of the nozzle hole number and size of the diesel pilot injector on ethanol combustion and engine performance is evaluated based on an injection timing sweep using three diesel injector configurations. The tested configurations have the same geometric total nozzle area for one, two and four diesel sprays. The relative amount of ethanol injected is swept between 78 – 89% and 91 – 98% on an energy basis at low and high load, respectively. The results show that mixing-controlled combustion of ethanol is achieved with all tested diesel injector configurations and that the maximum combustion efficiency and variability levels are in line with conventional diesel combustion. The one-spray diesel injector is the most robust trigger for ethanol ignition, as it allows to limit combustion variability and to achieve higher combustion efficiencies compared to the other diesel injector configurations. However, the two- and four-spray diesel injectors lead to higher indicated efficiency levels. The observed difference in the ethanol ignition dynamics is evaluated and compared to conventional diesel combustion. The study broadens the knowledge on ethanol mixing-controlled combustion in heavy-duty engines at various operating conditions, providing the insight necessary for the optimization of the ethanol-diesel dual-injection system.

由于乙醇的特性和生产途径，乙醇是化石燃料的一种有价值的替代品，在CO ₂，NO _x方面具有潜在的好处。，并减少烟尘排放。乙醇的自燃抗性要求在重型应用的压燃式发动机中使用点火触发器，在当前研究中，该发动机是柴油引燃喷射。在重型单缸发动机的低负荷点和高负荷点上，通过实验研究了通过分离的喷油器同时直接喷射纯乙醇作为主要燃料和柴油作为引燃燃料。基于使用三种柴油喷射器配置的喷射正时扫描，评估了柴油引燃喷射器的喷嘴孔数量和尺寸对乙醇燃烧和发动机性能的影响。经测试的配置具有相同的几何总喷嘴面积，可用于一，两和四个柴油机喷雾。在低负荷和高负荷下，按能量计算，注入的乙醇的相对量分别介于78 – 89％和91 – 98％之间。结果表明，使用所有经过测试的柴油喷射器配置均可实现乙醇的混合控制燃烧，并且最大燃烧效率和可变性水平与常规柴油燃烧一致。与其他柴油喷射器配置相比，单喷雾柴油喷射器是乙醇点火的最强大触发器，因为它可以限制燃烧变化并实现更高的燃烧效率。但是，两喷和四喷柴油喷射器导致更高的指示效率水平。评估所观察到的乙醇点火动力学差异，并将其与常规柴油机燃烧进行比较。