Exhaust emission characteristics of a marine diesel engine with an electronically controlled fuel injection system --on the case of marine diesel oil--

摘要

An electronically controlled system for fuel injection is one of techniques to improve thermal efficiency and to reduce harmful emissions simultaneously. The authors applied an electronically controlled system to a diesel engine, a 3-cylinder medium speed 4-cycle engine of 257 kW/420 rpm at maximum continuous output power. On the system, the fuel injection pump is driven by hydraulic pressure and the hydraulic pressure line is electronically controlled to change fuel injection timing. Fuel injection profiles different from that of a camshaft are also obtained. The test engine was operated over 25% load to 100% load of maximum continuous output with a propeller law. At low load conditions, thermal efficiency, NOx emission and PM emission characteristic could be improved simultaneously, by optimization of injection timing. Regarding PM emission, it was improved drastically throughout the whole engine load range, which is considered to be caused by that the increase in pressure rising speed improved atomization characteristics at initial period of injection.