Do altitude affect emissions on a Heavy-Duty Diesel Engine?

[Dvhez]

I understand that a genset should be derated according to the meters above sea level, however, what happens to emissions?. If the motor burns X amount of fuel, that fuel must represent the electrical energy produces. Derating is due mostly by engine temperature -among other factors- (correct me if I'm wrong).

 

[itsmoked]

De-rating is because of thinner air, so less air to mix fuel with. So less fuel, so less power. Because the fuel is reduced, power is reduced, and even emissions should be reduced because less fuel is being burned. (modern engine and fuel delivery assumed which provides for altitude compensation)

If you're talking about an older non-altitude compensated engine then yes, less power for the same reason, but because the fuel isn't being reduced to keep the mixture dialed in you will get more emissions. This, because the mixture is too rich and incompletely burned and worse the governor will advance in an attempt to still provide the power needed making it all worse yet.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[JohnMcNutt]

Traditionally, de-rating was to keep turbocharger RPM under control. Less air = higher turbo RPM to produce the same level of boost. This was even the case before wastegates became standard.

There must be some effect on radiator cooling, also. If the alternator itself has a max altitude rating, the radiator must suffer the same effect.

Theoretically, the emissions should not change much, if the turbocharger is able to supply the same amount (lbs/hour) of air.