中文摘要：

采用超声波乳化法制备了玉米秸秆热解生物油质量分数分别为5％、10％、15％和20％的生物油／柴油乳化油，分别记为CSB5、CSB10、CSB15和CSB20，然后在一台未作改动的直喷式柴油机上研究了其燃烧和排放特性，并与燃用0号柴油进行了比较，旨在为生物油在柴油机中的应用提供依据和理论指导．结果表明，随着生物油质量分数的增加，乳化油的滞燃期逐渐延长，预混燃烧放热量和预混燃烧期增加，燃烧持续期缩短；燃烧放热率峰值和最大压力升高率先增加后降低，最高燃烧压力和燃烧温度逐渐降低．燃用CSB5和CSB10时的燃油经济性与柴油相当，而燃用CSB15和CSB20时的燃油经济性较柴油的略差．与0号柴油相比，随着生物油含量的增加，乳化油的NOx排放逐渐降低，HC和CO排放逐渐增加；碳烟排放先降低后增加，CSB5和CSB10的碳烟排放比柴油的排放值低，而CSB15和CSB20的碳烟排放却比柴油的排放值略高．

英文摘要：

The experimental bio-oil was produced from corn stalk through fast pyrolysis process. In this paper, four emulsions with 5%, 10%, 15% and 20% by mass fraction of corn stalk bio-oil （CSB）in diesel fuel, represented by CSB5, CSB10, CSB15 and CSB20, respectively, were prepared by the ultrasonic emulsification method. Then, the combustion and emission characteristics of an unmodified direct injection diesel engine operating on the four emulsions were studied and compared with those of No. 0 diesel operation in order to provide the basis and theoretical guidance for the application of bio-oil in diesel engines. The results showed that, with the increase of CSB mass frac- tion in the emulsions, the ignition delay lengthens, both the heat released during the premixed combustion phase and the premixed combustion duration increase, while the total combustion duration shortens. With the increase of CSB mass fraction in the emulsions, the peak values of both premixed burning rate and pressure rise rate increase first and then decrease, while those of in-cylinder pressure and combustion temperature decrease. In addition, the fuel econ- omy of CSB5 and CSB10 is comparable to that of No. 0 diesel, while the fuel economy of CSB15 and CSB20 is slightly poorer than that of No. 0 diesel. In comparison with No. 0 diesel, NOx emissions of all the emulsions are lower, while HC and CO emissions are higher. Furthermore, these trends are more remarkable with the increase of CSB fraction in the emulsions. Smoke emissions of the emulsions decrease first and then increase with the increase of CSB fraction in the emulsions. Meanwhile, smoke emissions of CSB5 and CSB10 are lower while those of CSB15 and CSB20 are slightly higher than those of No. 0 diesel.