March 11, 2003

MAN B&W backs FWE for NOX reduction
The nitrogen oxide NOX) reduction technology based on fuel water emulsion injection (FWE), developed by MAN B&W Diesel, has proved a success in series operation.

Now, says MAN B&W, the FWE approach is being adopted by competitors who had previously taken different approaches.

Introducing water in the diesel engine combustion chamber reduces temperature peaks during the combustion process. This results in a clearly reduced NOX content in the exhaust gas of two-stroke and four-stroke engines.

There are three possibilities for introducing water into the cylinder:

  • admix to the fuel (emulsion),
  • direct injection or
  • humidification of the aspirated combustion air.

All three possibilities have been tested in practical operation: direct water injection (DWI), fuel water emulsion (FWE) and for an even more significant reduction of nitrogen oxide humidification of the aspirated combustion air in the Humid Air Motor (HAM).

As early as in the 1980s, MAN B&W Diesel thoroughly tested both emulsion injection, which had first been tested on gasoline engines in the fifties, and direct water injection on its engines.

Because of the significant advantages of fuel water emulsion, MAN B&W Diesel opted for the further development of this technique, while competitors invested a lot of time and money in DWI.

Now, despite initial positive reports on the practical application of DWI, which pointed to the superiority of that technology, competitors are now switching to FWE.

MAN B&W Diesel, however, says it now has a lead of "many years of development work and practical experience."

Four ro-ro vessels with 12-cylinder V-engines of the 48/60 series, equipped with FWE technology, have been in service since 2000. And MAN B&W claims even more extensive experience with regard to stationary two-stroke engines used for power generation and for main marine propulsion,

MAN B&W notes that from the beginning of the eighties, which means for more than 20 years, FWE has proved a success during practical operation in various engines.

The lowest nitrogen oxide output is achieved by the humidification of the aspirated combustion air in the Humid Air Motor (HAM). MAN B&W is already applying this technology in the Baltic Sea ferry Mariella.

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