Reduction of Unburned Hydrocarbons in Diesel Emission with Low Distillation Temperature Fuels

Abstract

In a small DI diesel engine, reducing the compression ratio to 16 is appropriate to reduce smoke emissions without deterioration of NOx and thermal efficiency. However, with a lower compression ratio, a low coolant temperature, or during the transient state following an increase in load, THC emissions significantly increase when using ordinary diesel fuel. In fully-warmed steady state operation with a compression ratio of 16 and diesel fuel, THC is reasonably low, but the level increases with lower coolant temperature or during the transient period just after increasing the load. This problem can be eliminated with a low distillation temperature fuel such as normal heptane. Benzene, butadiene, and other unregulated emissions also increase under the high THC conditions with the diesel fuel.