Why EGR valve got so popular even if it create more harm than good?
Why EGR valve got so popular even if it create more harm than good?
(OP)
Everything is in the title. It seem that in almost all diesel engine, the EGR valve is clogging the intake until there's so much restriction that the engine begin to smoke a lot, starving for air. Next thing you learn, your engine is creating even more pollution than it would've create without any EGR valve. Why every constructors are still using such a crude system?





RE: Why EGR valve got so popular even if it create more harm than good?
What Diesels have EGR?
Mike Halloran
Pembroke Pines, FL, USA
RE: Why EGR valve got so popular even if it create more harm than good?
See the link below for some information.
http://www.myturbodiesel.com/1000q/egr.htm
On my VW diesel, I used a vag-com to minimize the EGR flow. I have never had a problem with intake goo; however, I only have 110,000 miles on the car. In addition, I suspect that I am pumping a little more pollution out than a unmodified computer controlled TDI VW; however probably much less pollution than a TDI with a fouled manifold.
RE: Why EGR valve got so popular even if it create more harm than good?
Light duty European & Asian diesels have used cooled EGR since the late 90's, also to meet emission regulations. Any light duty diesels sold in the US since ~2002 have also used cooled EGR to meet emission regulations.
I'm sure there are better informed experts on diesel combustion in this forum than myself, but I'll do my best to explain.
The main purpose of EGR is to dilute the mixture in the zone where combustion is occuring (of course it dilutes the mixture everywhere, but the zone of combustion is where it matters). The purpose of dilution is to reduce peak temperature, by adding inert matter mixed with the reactants, that absorbs heat without adding to the heat release. NOx formation is a strong function of peak temperature, which is why this strategy is very effective.
The purpose of cooling the EGR is to increase the density of the inert matter, so the manifold and cylinder pressures can be reduced for given EGR mass flow rate. Also, this not only reduces the peak gas temperatures, thereby helping with NOx reduction vs non-cooled EGR, it also reduces the peak temperatures and thermal loading on critical components like pistons and exhaust valves.
EGR is now a fact of life for diesel engines in tightly emission regulated markets. Increasingly, it will also become the norm for high power density (i.e. boosted) spark ignited engines in these markets also.
RE: Why EGR valve got so popular even if it create more harm than good?
I know it is there to reduce NOx emission but the point is that it's doing more harm than good. Why is it still necessary? Every modern diesel use urea aftertreatment to remove NOx so it seem that the EGR valve is redundant.
RE: Why EGR valve got so popular even if it create more harm than good?
Pretty much all of them made now. Well for automotive applications anyway.
EGR is a great way to ruin HP and fuel economy. It is counter to anything that is done to increase power in a reciprocating internal combustion engine.
It is done to remove oxygen and cool the combustion process. To reduce Nitrous oxides. I guess I better stop here.
RE: Why EGR valve got so popular even if it create more harm than good?
Not true. For heavy duty diesels, there are two NOx reduction strategies: urea or EGR. Broadly speaking, USA companies favour urea; Europeans favour EGR.
Diesel engine manufacturers are bound by legislation.
- Steve
RE: Why EGR valve got so popular even if it create more harm than good?
Hmmn, last time I checked, it was the other way around. Have things changed since 2007?
RE: Why EGR valve got so popular even if it create more harm than good?
- Steve
RE: Why EGR valve got so popular even if it create more harm than good?
- Steve
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
How will adding more fuel reduce black smoke.
You obviously live in a cold climate and presume everyone else does.
Water injection may help to remove carbon deposits, depending on where they are.
A small siphoning problem or excessive flow can cause hydraulic lock in a diesel a lot easier than it does with a spark ignition engine.
It sounds like a decoke of the EGR area should be a regular service item like changing oil and filters. My car (not diesel) actually has a fine mesh filter on the EGR supply.
Regards
Pat
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RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
Adding extra fuel to a diesel at full throttle will overfuel and result in black smoke. Alcohol is a fuel and consumes oxygen as it burns.
Alcohol in the water of a water injection system is useful to prevent the growth of algae which can block nozzles.
Water injection is very effective at removing coke from the chamber, but not from upstream of the inlet valve.
Regards
Pat
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RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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for site rules
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
Even Caterpillar added EGR to their engines beginning in 2007. In the future, it's likely that everyone will have both EGR and aftertreatment, although there are more aftertreatment schemes than just the urea-based ones.
RE: Why EGR valve got so popular even if it create more harm than good?
Truck stops all across the US are gearing up for the urea infrastructure.
Once manufacturer (Navistar) will use only cooled EGR to meet the regs, based on techniques developed by MAN in Germany.
Regarding the comment about Caterpillar, the poster may not realize that they announced last year they are ceasing production of on-road diesel engines beginning in 2010.... They were the last to hold out using cooled EGR, and attempted to meet the 2007 regs using adaptations to their ACERT technology, but fell behind other manufacturers (e.g. Cummins) and lost market share as a result.
RE: Why EGR valve got so popular even if it create more harm than good?
- Steve
RE: Why EGR valve got so popular even if it create more harm than good?
RE: Why EGR valve got so popular even if it create more harm than good?
I recall spending two hours scraping about a half liter of carbon from my TDI intake manifold. The port passages could barely flow any air and the plenum was likewise nearly solid with carbon.
In the combustion chamber, I could see water helping. That is not where the problem is occurring, though.