Search Results

1 In recent years, the steep rise in crude oil costs, demand for light oils such as gasoline, kerosene, diesel oil has been increasing, and increased sophistication of oil refining technology has led to a tendency towards the production and supply of low quality marine residual fuel oil (hereinafter MFO). Among the many types of degradation, deterioration of the combustion quality of MFO in large marine diesel engines is of particular concern, as it causes such problems as poor combustion in diesel engines. In addition, there is a large risk that these problems will be associated with serious problems like piston ring damage and abnormal wear of the cylinder liner. This paper presents the results of the combustion qualities and general properties of actual marine fuel oil analysis using a constant volume combustion chamber instrument (Fuel Ignition Analyzer, hereinafter FIA), and further describes the relationships between combustion quality, general properties and engine problems.

Measurements are presented of droplet characteristics and air velocity in the cylinder of a 0.36 litre four valve engine, equipped with an sohc VTEC-E valve train and port injection. The results show that injection at crank angles, θinj(s), when the inlet valve is open results in most of the liquid volume flux being in the form of droplets with Sauter mean diameter between 20 and 30 mm which strikes the sleeve up to about 2.5 cm below the exhaust valves, thus generating a locally rich cloud there. The amount of liquid phase gasoline passing through the plane 16 mm below the spark plug gap increases with θinj(s) up to 50 CA after intake TDC and this, together with the crank angle of droplet arrival and vapour generation, controls stratification of the gaseous fuel phase. The optimum injection time is when the fuel-rich cloud is generated so that the tumble vortex convects it to the spark plug at the time of ignition.