EGR Operation

[TexasTruck]

When is it opened and closed?

I'm curious, if it's closed all the time, wouldn't the cooler get fowled quicker from the soot and what not?

Also, wouldn't the cooler get very hot due to the trapped exhaust?

Since the cooler is a heat exchange process it seems like it would make the truck run hotter?

And as the cooler fowls the heat exchange process becomes less efficient so the cooler gets hotter and hotter.

Thanks,
Scott

[LoNE WoLF]

If the egr valve is in the closed position. Then there would be no flow of exhaust gasses through the cooler. I would think that the exhaust gasses would seek the least path of resistence. I don't think that they would build up in the cooler circuit. When the egr opens, now you have a path for the exhaust gasses to flow through.

[K9crew]

From what I've read "EGR flow is aided by increasing exhaust backpressure through the use of a variable geometry turbocharger or by causing the engine to scavenge exhaust with the aid of an intake throttle plate" so one would assume that the EGR valve diverts the maximum amount of exhaust gasses back into the engine when exhaust back pressure is at a maximum. Supposedly this is to lower combustion temperatures which reduces NOx emissions but increases particulate emissions. The exhaust gas is cooled to around 400F before it's returned to the engine. This is what I've read and not what I know.

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