Sách New HFO Common Rail System for Mediumspeed Diesel Engines

New HFO Common Rail System for Mediumspeed Diesel Engines
Introduction
The Diesel engine is and will, also in the future, be one of the most eco­nomic possibilities for converting chemical fuel energy into mechanical energy. This applies both to the automotive range and the propulsion of large vessels or power plant generators. In order to make use of the Diesel engine’s economy also in the future, it will, with regard to environmental aspects, become more and more important to prevent visible and, in particular, pollutant compo­nents from being contained in the exhaust gas. Already at an early stage, MAN B&W attached great importance to this requirement , carried out corresponding develop­ment work and launched exhaust gas optimised engines [1]. Following the philosophy of environment-friendly engine development, CR will, as a next step, be introduced for MAN B&W engines.
Due to an electronic control system’s degrees of freedom, CR now offers engine developers a considerably wider spectrum of injection curve design, i.e. total combustion will prevent harmful constituents from being produced in the exhaust gas. When taking all possibilities of com­bustion process design into consid­eration, one must be fully aware of the fact that the injection system and, particularly, CR, is one of the most important components of an engine and that the engine is no longer functional if the injection system fails. The development of CR focused, in addition to functionality and represen­tation of the degrees of freedom, particularly on its reliability.
In order to take a decisive develop­ment step forward in engine technol­ogy with the help of CR, relevant development targets were precisely fixed. Optimum combustion requires, in addition to the degrees of freedom, i.e. injection start, injection quantity and injection pressure, the realisation of pilot and post injection. As the already existing engine series is to be equipped with CR, the system had to be designed in order to permit mounting on the engine without constructive interventions. Due to this requirement, the mechatronic compo­nents could not be accommodated in the cylinder head. As our engines are heavy fuel oil compatible, the fuel-relevant conditions, such as abrasive and corrosive constituents and high temperature, must be fulfilled with the utmost reliability and the usual maintenance intervals.
With regard to the success of a new development, it is of fundamental importance that the courses are already correctly set during the development phase. For this reason, the different system possibilities, including one and two-circuit sys­tems, were tested in pre-studies on an L 16/24 engine [1]. In this connec­tion, it was very soon evident that the final development solution could only be a one-circuit system as it proved that the requirement for a variable design of the injection curve can, system-dependent, not be achieved with a two-circuit system.