MAN B&W 6L32/40

June 28, 2004

MAN B&W introduces new common rail medium speed diesel

Using a technology that has helped sister company MAN Nutzfahrzeuge AG win the European Truck Racing Championship, MAN B&W is now offering a new medium-speed, four-stroke marine engine, the 32/40CR, featuring common rail fuel injection. The particular common rail technology being used has been developed from a system successfully employed in trucks by sister company MAN Nutzfahrzeuge AG.

“It was a strategic decision to develop common rail for our engines ourselves in order to do better than what would have been possible with existing, external systems,” says MAN B&W executive board member Fritz Pape.

“In developing our injection systems we have been able to build on many years of experience,” emphasizes the Head of Research & Development, Dr. Ralf Marquard.

Some 9,000 MAN trucks are already on the road with common rail technology.
In common rail diesel engines fuel is injected into all the cylinders via a “common rail.” The generation of pressure and injection of fuel are not interconnected. Unlike in conventional systems, the injection pressure is independent of the engine speed. Thus there is always full pressure available.

The fuel is first stored in the fuel line and then, when a signal is given by the engine controls to the magnetic valves, it is injected into the cylinders. This creates an extremely fine fuel-air mixture which burns particularly efficiently.

For the engineers at MAN B&W the challenge was to apply this injection system to large marine engines—and to adapt it for operation on heavy fuel oil, which means dealing with a fuel heated to 150°C.

Click here for a full technical paper on the work involved

Tthe new MAN B&W common rail engine is especially designed for reliability. The whole system, including the electronic controls is fully redundant, i.e. every major function has a backup. Thus there are at least two high-pressure pumps to every machine, ensuring that the pressure necessary for fuel injection is available, even if one pump fails.

Unlike in most other common rail engines, the MAN injection system is based on conventional pressure-controlled injection. In usual stroke-controlled systems there is a permanently high pressure of 1,600 bar, for example, at the needle seat near the combustion chamber.

In the MAN B&W system, the pressure on the valve needle is released by means of the solenoid valve controls which is located away from the cylinder head, at the common rail accumulator. As a result there is no permanently full pressure on the valve needle seat next to the combustion chamber and the electronic components are protected.

Common rail injection makes it possible to control combustion precisely and, within the operating range of the engine, flexibly. This lowers the fuel consumption.
Optimized fuel injection also diminishes combustion noise and the emission of pollutants in the exhaust. Thus soot emission at part loads is reduced to a level below the visibility limit. This is becoming increasingly significant in marine applications as pollutant emission limits are becoming increasingly stringent worldwide. In particular, start-up soot should be avoided. Common rail technology proves a particular advantage at low speeds and when operating conditions change fast, for example in suction dredgers or in cruise liners travelling very slowly in coastal waters.

Field Trials
Extensive practical testing of the new MAN B&W common rail technology has been under way since the beginning of the year.

One of the five auxiliary engines of the CORNELIA MAERSK, a container vessel (6600 TEU) of the A.P. Moeller Group, is equipped with the new technology. The results so far, says MAN B&W, are excellent: “The engine has been performing with convincing results for more than 1200 operating hours,” says Stephan Haas who is assisting in the field trial from the development engineering side. The 32/40CR series engine will be available from 2005 onwards. Larger as well as smaller types are in the pipeline. Thanks to its modular design, the MAN B&W common rail system can also be retrofitted in almost all MAN B&W marine diesel engines.

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