F-T柴油在直喷式柴油机中燃烧与排放特性的研究

煤通过Fischer-Tropsch (F-T)合成可得到十六烷值高、硫和芳香烃质量分数极低的F-T柴油。研究分析了未作改动的单缸直喷式柴油机燃用F-T柴油时的燃烧和排放特性。结果表明，与燃用0号柴油相比，燃用F-T柴油时的滞燃期平均缩短18.7%，预混燃烧放热峰值降低26.8%，扩散燃烧放热峰值较高，燃烧持续期相当。燃用F-T柴油时的最高燃烧压力略低，最大压力升高率显著下降，机械损失和燃烧噪音较小，燃油消耗率和热效率都得到显著改善。燃用F-T柴油可同时降低CO、HC、NOx和炭烟排放，其中NOx和炭烟分别平均降低16.7%和40.3%。研究表明，F-T柴油是柴油机良好的清洁代用燃料。

Combustion and emission characteristics of a direct injection diesel engine operating on Fischer-Tropsch diesel fuel

Through Fischer-Tropsch (F-T) synthetic process, coal can be converted to F-T diesel fuel that has high cetane number, very low sulfur and aromatic contents. This paper presents the research results of an unmodified single-cylinder direct injection diesel engine operating on F-T diesel fuel. The indicated pressure diagrams and injector needle lifts were recorded and the combustion and emission characteristics were evaluated and compared with those of conventional diesel fuel operation. The results showed that F-T diesel fuel exhibits a 18.7% average shorter ignition delay, a 26.8% average lower peak value of premixed burning rate, a higher maximum diffusive burning rate and a comparable total combustion duration when compared to conventional diesel fuel. In addition, F-T diesel engine has a slightly lower peak combustion pressure, a far lower rate of pressure rise, and a lower mechanical load and combustion noise. The brake specific fuel consumption is lower and the effective thermal efficiency is higher for F-T diesel fuel operation. CO, HC, NO_x and smoke emissions with F-T diesel fuel are reduced at all test speed-load points when compared to conventional diesel fuel. On average, NO_x and smoke emissions are reduced by 16.7% and 40.3% respectively with F-T diesel fuel. The study demonstrates that F-T diesel fuel is an excellent clean alternative fuel for diesel engines.