廃食油バイオディーゼル燃料の直噴式ディーゼル機関適用化研究

―第2報噴霧および着火・火炎特性の基礎解析

抄録

The combustion and emission characteristics for two waste cooking oils were investigated in detail. One fuel was the methyl esters in waste cooking oil. This fuel is in routine use in Kyoto City for a garbage collection vehicle with DI diesel engine (B100) and a city bus (B20; 80% by volume gas oil is mixed into B100) as an alternative fuel for gas oil. The other is fuel created by removing impurities from raw waste cooking oils. In order to improve the fuel properties, kerosene is mixed 70% by volume in this fuel. The mixed fuel (i-BDF) is used in several trucks in Wakayama City.
In the experiments, spray and combustion characteristics were investigated inside a rapid compression and expansion machine (RCEM) . The spray characteristics were measured by shadow-photography. We found that the spray tip penetration is greater and the spray angle is smaller for waste cooking oils than for gas oil. The combustion characteristics were measured by direct photography and imaging of OH chemiluminescence. As a result, flame luminosities in waste cooking oils are relatively low; in particular, soot formation in the combustion flame was found to be decreased in the case of B 100.