聚甲氧基二甲醚混合燃料喷雾特性试验研究

Spray Characteristics of Polyoxymethylene Dimethyl Ethers Blended Fuels

发展替代燃料是缓解石油能源短缺和环境污染的重要手段,在众多替代燃料中,含氧燃料因为其可再生、含碳量较低、能降低尾气排放等优势,得到了极大的发展。聚甲氧基二甲醚(PODE)、乙醇和生物柴油都是极具发展潜力的含氧替代燃料。在实际发动机中,替代燃料的喷雾行为直接影响后续的燃烧与排放过程。考虑到PODE可作为柴油-乙醇燃料的助溶剂,同时能弥补生物柴油高黏度和低挥发性的缺点,分别对柴油-乙醇-PODE和生物柴油-PODE混合燃料在定容燃烧室中的喷雾特性进行了研究。结果表明:在柴油中添加PODE对混合燃料的喷雾贯穿距(STP)影响不大,而在生物柴油中添加PODE,混合燃料的STP随着PODE比例的增加先增后减。在柴油中添加PODE和乙醇可以增加喷雾锥角(SCA),改善径向扩散,但对柴油的喷雾投影面积(SPA)影响不大,混合燃料对空气的卷吸能力与柴油相似。在生物柴油中添加PODE,混合燃料的喷雾锥角和喷雾投影面积均明显大于生物柴油,能够有效改善生物柴油的喷雾质量。

The development of alternative fuels is an important means to alleviate petroleum energy shortage and environmental pollution.Among numerous alternative fuels,oxygen-containing fuels have been greatly developed because of their renewability,low carbon content,and ability to reduce exhaust emission.Polyoxymethylene dimethyl ethers(PODE),ethanol and biodiesel are all oxygen-containing alternative fuels with great development potential.In actual engines,the spray behavior of alternative fuels directly affects the subsequent combustion and emission process.PODE can be used as a solvent aid for diesel-ethanol fuel and can make up for the shortcomings of high viscosity and low volatility of biodiesel,the spray characteristics of diesel-ethanol-PODE and biodiesel-PODE blended fuels were hence studied in a constant volume combustion chamber.The results show that the spray tip penetration(STP)is little influenced after mixing PODE in blended fuel with diesel,and first increases and then decreases with the increase of PODE in blended fuel with biodiesel.Adding PODE and ethanol to diesel can increase the spray cone angle(SCA)and improve the radial diffusion,but has little effect on the diesel spray projected area(SPA),and the entrainment ability of blended fuel to air is similar to that of diesel.Adding PODE to biodiesel significantly increase the spray cone angle and spray projected area of blended fuel,which can effectively improve the spray quality of biodiesel.