The Influence of Cellulosic Liquefaction Fuel, FAME and Diesel Fuel Mixture on Diesel Engine Performance

The cellulosic liquefaction fuel (CLF) was made from woods by the direct liquefaction process. The compression ignition did not occur when neat CLF was supplied for diesel engines, because CLF mainly consisted of aromatic compounds. CLF could not be completely mixed with diesel fuel, however, CLF and diesel fuel could be blended when FAME was mixed as a solvent. Coconuts-oil methyl ester (CME) was used and 5 wt% that was allowed mixing ratio to diesel fuel in JIS was mixed. To clarify a desirable CLF fraction for diesel engines, CLF was divided into two fractions by the fractional distillation: 473 to 523 K (CLF1), 523 to 573 K (CLF2). The purpose of this study is to analyze ignition characteristics and performance of diesel fuel-CME-CLF blends and the tested weight mixing ratio of CLF were 5, 10, 15 and 20 wt%. It was confirmed engine could be stably operated for both CLF1 and CLF2 mixed fuels. The brake thermal efficiency of CLF mixed fuel was almost equal to that of diesel fuel, however high NOx concentration was emitted at high load. This is because the combustion gas temperature rose by a rapid combustion pressure increase due to ignition delay. HC concentration of CLF mixed fuel was slightly higher than that of diesel fuel at low load because unburned gas increased by the ignition delay. However, CO and HC concentrations were decreased in high load and smoke concentration of CLF mixed fuel was lower than that of diesel fuel because a lot of oxygen atoms were contained in CLF. The engine performance of CLF1 mixed fuel was almost similar to that of CLF2 mixed fuel, however CLF1 mixed fuel had superior ignitability. Therefore, it was possible to operate diesel engine without any influence on engine performance when diesel fuel-CME-CLF blends were used.