A new bio-fuel i.e. the cellulosic liquefaction fuel (CLF) was developed for diesel engines. The cellulosic liquefaction fuel (CLF) was made from woods by the direct liquefaction process. CLF could not be completely mixed with diesel fuel, however CLF could be mixed with Fatty Acid Methyl Ester (FAME) and a diesel engine could be operated by CLF and FAME blends. In this study, CLF was divided into three fractions: 473 to 523 K (CLF1), 523 to 573 K (CLF2) and 573 K or more (CLF3) by fractional distillation in order to find CLF fraction which was suitable for diesel engine, and coconuts oil methyl ester (CME) was used as FAME. In the fuel droplet combustion tests, the combustion durations of CLFs were longer than those of diesel fuel and CME, and the combustion duration increased as the distillation temperature range rose, because CLF contained a lot of flame-resisting components like aromatic compounds. Each CLF fraction was mixed with CME to provide engine and tested weight mixing ratios of CLF in CME-CLF blends were 0, 5, 10 and 15 wt.%. All test fuels could be used for diesel engine, when the mixing ratio of CLF was up to 15 wt.%. The thermal efficiency of CLF1-CME blends is slightly higher than those of CLF2 and CLF3. Exhaust gas emissions increased as the mixing ratio of CLF increased because the ignitability of CLF was inferior. In the cold start test, crank angle at ignition delayed as the mixing ratio of CLF increased, however the ignition delay was improved as engine was warmed up. The crank angle at ignition became late in the order of CLF1, CLF2 and CLF3-CME blends, so that CLF1-CME blends showed good ignitability compared with other CLFs. Therefore, a low temperature distillation fraction of CLF is suitable for diesel engines.
