I think trucks and railroads are related in this case. The CARB proposal for a locomotive diesel engine Tier 5 are almost identical with heavy truck Tier 4.
Regarding truck testing in laboratory. The Mercedes fuel efficiency data I cited are from road tests. The three trucks were tested parallel at the same time on a hilly test circle in August 2016. The Euro II had run 375,000 miles, the Euro III 35,000 miles, and the Euro VI 5,000 miles. The test was conducted by a trucking magazine supervised by Dekra, an independent test organisation. No Mercedes personnel was involved.Regards, Volker
trucks and locomotives are indeed related, just the truck engines are smaller and a few years more advanced. But those few years of advance are showing the failures as well.
As for the reference to the Mercedes test, well now I understand the big difference. Frankly too many uncontrolled variables for it to be valid testing. Comparing a 20 year old truck with 10times the accumulated wear of the next vehicle, which itself had 7 times the accumulated wear is just a way to prove a new truck runs better than a worn out truck.
Differences in aerodynamics, transmission, weight, horsepower, etc can account for a large portion of the difference.
Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction
ruderunnertrucks and locomotives are indeed related, just the truck engines are smaller and a few years more advanced. But those few years of advance are showing the failures as well.
The forum is about railroad locomotives (with Diesel or electric engines), not truck engines, even if Diesel.
C&NW, CA&E, MILW, CGW and IC fan
VOLKER LANDWEHRThere is the failure of EGR with heavy truck engines because of EGR valve problems. Having higher maintenance costs and worse fuel efficiency. Fleet loss about 30%. But GE and EMD Tier 4 diesel engines seem to work satisfactorily with EGR said by GE to have better fuel efficiency and less maintenance costs.
To keep this directed at rail and options, a large part of the difference is in the different engine types and load cycles.
Remember that EGR is intended to replace part of the intake charge with neutral 'spent gas' instead of more atmospheric nitrogen -- see the related FGR in powerplants for a more interesting utilization of the same principle. For the same reasons turbocharging generally uses intercooling rather than staged overboost to increase effective charge density, EGR usually 'throws away' much of the heat energy in the spent gas, but it can be difficult in confined space and with high gas mass flow to get the gas cooled, and the crap it may contain removed, before allowing it into the combustion chamber with the atmospheric oxygen.
Locomotive engines peak relatively low in the rpm range, and their rpm does not need to load-follow wheel speed very quickly. There is plenty of room for exhaust-gas cooling, and for arrangements that do not degrade or leak engine coolant easily or that thermal-cycle until leaking is enhanced. Look at a couple of the pictures M636C provided of mufflers and EGR coolers and compare the room, and the lengths of interconnection, that would be needed for similar implementation on a Class VIII motor.
I am looking forward to Trains Magazine doing an 'expose' on the things that have killed so many "green" locomotive projects, from the Green Goat through the GE hybrid to the discussions over No-NOx standards imposed on road locomotives as well as switchers.
The problem with EGR peroid with diesel engines is with the particulate matter that is left over from the combustion process. We have yet to figure out how to deal with in on the OTR side at all sooner or later those particles will wear a hole into a cooling system your using and both GE and EMD are using water based cooling systems for their EGR coolers and water and oil do not mix at all. When those go bang on one of those big boys I do not want to be the machinist in the shop that has to tell his foreman that they have to replace everything in the block. Just imagine 200 gallons of mayo in a crankcase of a locomotive getting into the turbos rockers cam bearings main bearings and into the oil passages.
I have some words that my shop would like to tell you have fun and be ready to replace your hot tanks filters at least 2 times per occasion when this happens. Yeah it is that bad.
schlimm ruderunner trucks and locomotives are indeed related, just the truck engines are smaller and a few years more advanced. But those few years of advance are showing the failures as well. The forum is about railroad locomotives (with Diesel or electric engines), not truck engines, even if Diesel.
ruderunner trucks and locomotives are indeed related, just the truck engines are smaller and a few years more advanced. But those few years of advance are showing the failures as well.
And what's happened to otr engines is going to happen to locomotive engines. Ignore it now if you like, but it will be spoken about later. What's going to be your response then?
STCO is involved with a small family-owned, possibly shoestring operation, like most of those outfits in Morton. If we were serious about the effects of emission controls on trucks (not exactly a new event, BTW) it would be more instructive to hear from one of the large operators.
The GE Tier 4 locomotives are outfitted with all forms of performance monitors of all areas of their operation and communicate the data that is captured with both the owner of the locomotive and GE on a regular periodic basis. Those receiving the data have diagnostic programs running that analyize the data on a near real time basis and formulate warnings when necessary to take the locomotive off line and out of service if and when the diagnostics indicate it is necessary. I suspect EMD's have similar sensors and diagnostics, but don't know that for a fact.
There are a multitude of things are measured - more than you can really wrap your mind around (if in doubt of the kinds of things that get measured - just look the dealers read out of what is sent through the OBD port on your vehicle in real time - not just the OBD diagnostic trouble numbers). I suspect the locomotive owner will know of a cooling system problem long before the crankcase lubricating oil has been turned to mayonaise.
Never too old to have a happy childhood!
schlimmIf we were serious about the effects of emission controls on trucks (not exactly a new event, BTW) it would be more instructive to hear from one of the large operators.
And why (especially when you yourself have just been repeatedly arguing 'truck operator' experience should not be discussed) would you expect one of the large operators to chime in here to contribute?
Insulting other forum members who engage in spirited and sometimes exaggerated discussion is one thing. Insulting others by extension, apparently just to score sarcasm points, is more than a violation of TOS, it's a violation of a sort of common decency. The point about experience of large fleet owners ... were it relevant to rail applications (and perhaps you can explain why it would be when the technical issues do not really differ between small and large truck fleets) ... could have been made without backhanding people I doubt you know.
250 trucks is not a shoestring operation in the OTR world Schlimn. Our revenue for last year was over 70 million dollars. We directly employ over 300 just on our trucking side close to 100 on our warehouse side. So if you think that is small time when were larger than 60 percent of the OTR carriers operating in the USA. Most OTR companies are small less than 20 trucks.
In railroad terms we are like the FEC or the old WC. Big enough that we can serve your needs but small enough that we care. There is nothing shoestring about how my boss runs his company end of story. If a driver reports any problems with his truck it is repaired. There is no bandaid repairs allowed.
The stuff we haul some of it if improperly handled is considered a freaking weapon of mass destruction. We handle Chlorine gas. You don't screw around at all with that.
Our out of service rate is less than half the industry average. A normal OOS rate is over 20% due to all the things that can place you out of service anymore. Over the last 2 years try less than 1 in 10 of our trucks gets placed oos after any inspection. That includes driver mechanical cargo all inspections. We have not had a failed drug test for active employees in over 3 years.
Now to get this thread back on track. Both the F125 and Siemens Charger that are being built with non GE or EMD engines the former has a Cat the other a Cummins. They both are equipped from their factory with EGR SCR and DPF to meet the emissions requirements. In fact Cummins when they announced their QX line stated the only easy way to meet current and any future regulations in emissions was to adapt OTR tech to locomotive engines. Amtrak and commuter lines must think so their ordering them.
Balt we also have those on our latest trucks and are taking oil samples weekly for testing. We just had one tested fine according to the oil samples. He got 30 mins out of the yard well we sent a replacement truck to him hook for his just got the report yesterday. Egr cooler failed motor is fried needs overhauling. Mileage on the engine 62k first oil change was done at 45k per factory specs. Cummins is putting a brand new engine in it they want to know why this one expired so fast.
just as an aside, STCO has experience with otr engines, my background is in light truck. Same experience with late model diesel emission controls. It will happen to even the best maintained locomotives.
Just a couple thoughts on why EGR cooler failures are more prevalent in the smaller engines...
Shadow brought up the"sandblasting" effect which is plausible. In the light truck world, the corrosive nature of the exhaust can develop compounds that eat even stainless steel..
RME mentioned heating cooling cycles and I wonder if that may help in locomotives. The corrosive stuff in exhaust tends to be relatively benign till mixed with water.
If everything stays hot, there's no real water. Vapor yes but it doesn't stay in the system very long. Otoh, shutting down and complete cooling allows for condensation and puddling. A couple drops of H2SO4 can do quite a bit of damage. How often do locomotives get a complete cool down?
Just occurred to me, someone mentioned the genset locomotives being unreliable. Any details about the failures? Are they EGR equipped? Hmmm.
RME schlimm If we were serious about the effects of emission controls on trucks (not exactly a new event, BTW) it would be more instructive to hear from one of the large operators. And why (especially when you yourself have just been repeatedly arguing 'truck operator' experience should not be discussed) would you expect one of the large operators to chime in here to contribute? Insulting other forum members who engage in spirited and sometimes exaggerated discussion is one thing. Insulting others by extension, apparently just to score sarcasm points, is more than a violation of TOS, it's a violation of a sort of common decency. The point about experience of large fleet owners ... were it relevant to rail applications (and perhaps you can explain why it would be when the technical issues do not really differ between small and large truck fleets) ... could have been made without backhanding people I doubt you know.
schlimm If we were serious about the effects of emission controls on trucks (not exactly a new event, BTW) it would be more instructive to hear from one of the large operators.
Oh give it up. It wasn't I who first questioned STCO's company's operations. It wasn't I who questioned the veracity of her comments on nuclear safety in Central Illinois. Insults?
schlimmIt wasn't I who first questioned STCO's company's operations. It wasn't I who questioned the veracity of her comments on nuclear safety in Central Illinois. Insults?
What do nuclear operations have to do with the competence of someone's boss, or truck-line owner? And, whether or not you were the first, you certainly piled it on enough on your own.
If someone who didn't know my wife's financials or policies made snarky reference to her 'shoestring operation' or implied guilt-by-association with presumably fly-by-night companies -- yes, I'd take it as an insult, and most anyone would understand that to be the intent as well as the effect.
RME schlimm It wasn't I who first questioned STCO's company's operations. It wasn't I who questioned the veracity of her comments on nuclear safety in Central Illinois. Insults? What do nuclear operations have to do with the competence of someone's boss, or truck-line owner? And, whether or not you were the first, you certainly piled it on enough on your own. If someone who didn't know my wife's financials or policies made snarky reference to her 'shoestring operation' or implied guilt-by-association with presumably fly-by-night companies -- yes, I'd take it as an insult, and most anyone would understand that to be the intent as well as the effect.
schlimm It wasn't I who first questioned STCO's company's operations. It wasn't I who questioned the veracity of her comments on nuclear safety in Central Illinois. Insults?
The first is an indication of her tendency to make unsupported (and in several cases absurdly untrue) remarks. She constantly references her relatives' company, thus fair game for criticism, mostly by others.
As to mild snarkiness, you yourself are hardly immune: [to Volker Landwehr] "You're an engineer, you read what Volvo wrote, and you still find it contradictory?"
RME We might take a leaf from the European cap-and-trade for carbon emissions to find a 'winning' strategy for reducing net NOx levels -- perhaps both focal and air-quality-management-district wide. And perhaps start reducing the Mickey Mouse piling-on of restrictions and annoyances on the OTR industry in California and other areas fond of manipulation...
We might take a leaf from the European cap-and-trade for carbon emissions to find a 'winning' strategy for reducing net NOx levels -- perhaps both focal and air-quality-management-district wide. And perhaps start reducing the Mickey Mouse piling-on of restrictions and annoyances on the OTR industry in California and other areas fond of manipulation...
It should be noted that the California State Senate has submitted a bill for a New Cap and Trade system that addresses many of the flaws in the original Schwarzenegger era legislation. The review of it I saw was that it might include nearly every suggested fix to Cap and Trade based on the issues the EU and Ca have seen with it in the past. Basically, it's the best version of cap and trade possible...if implemented as proposed.
That by the way is highly likely to make it to the governor's desk whereas I'd be shocked if the EPA even considered the request in the abstract right now.
YoHo1975They have no request related to trucking, a whole awful lot of it is irrelevant.
The relevance is in similarities of approach and technology, converging much more directly for railroad prime movers that are either derived directly from 'road vehicle' engines or that may suffer the same kinds of material damage or consequences that are reported for OTR practice.
I have seen some preliminary discussions of emissions reduction in the 'electrical generator set' size engines (e.g. the C175-20) or the designs accelerated to higher rpm (which I understood the larger Cummins QSKs to be). I think specific methods and instrumentation to determine NO emissions from such engines exists, but it is either kept proprietary as a manufacturer's advantage or in paywalled 'engineering-society' papers or discussions. What we have seen, or can deduce from pictures, does not necessarily tell us either about operating issues or likely/common-mode points of failure. More specifics here (perhaps from people like Entropy) might be highly valuable.
CARB's request could best be described as asking the EPA to set Locomotive requirements to match Tier 4 OTR plus some amount of zero emission. Is it a request that could be met by EMD and GE?
Taking up the second half first: GE was plainly involved in locomotive designs that could, if necessary, be easily adapted from "hybrid" to "plug-in hybrid" (as the difference is now categorized in automobiles). I am reasonably certain even from my own studies that an energy-storage system adequate for switching and transfer work can be made, and that approaches that optimize any cost-effective level of zero-emission road traffic that California would be willing to support or subsidize (rather than just 'mandate') can be made relatively easily and progressively. The issue is far more on the dollar, particularly the 'bang-for-the-required-bucks' side, than on what could be developed or built even with contemporary tech and near-OTS stuff.
The deep and troubling issue is the proposed No-NOx reduction in rail Tier 5. I don't know of a cost-effective way that can be achieved without considerable exhaust aftertreatment.
You want to know where the Genset engines come from. If they are Cummins they are bone stock ISX engines the same freaking ones my boss runs in his fleet. The same engine that a class 8 semi runs going down the road. The ones from Cat are based off their old C16 models which until Caterpiller left the OTR market was one of the best engines ever offered end of story. Cummins for their QSK line for the injectors and fuel system and this comes from our Cummins shop manager all they did there was adapt the ISX fuel system for the larger engines. The DPF's and SCR system on that engine is based off the exact same one that sits under one of the trucks my drivers runs down the road it just has more volume capacity. They are using more filter elements and larger SCR injections to get it down.
YoHo1975It seems to me that the easiest way to hit this might simply be to make one member of the set a "Slug" with batteries/Supercaps aka, not a slug.
That would be correct, but note that it would not be difficult to put charging means for an augmented battery/supercap genset on the approach track and hump alone for this service, which is precisely the place where continuous operation on the torque peak for a small 'sustainer engine' would be possible. It is only slightly more difficult to put full power pickup even at 25kV over the relatively short distance required, even to the point where 'energization on demand' could be used (more for political rather than engineering economy, I suppose). Note that if this is done for the benefit of 'low-income' people downwind, it's fully appropriate for Government subsidy or incentive for all the capital construction and equipment/improvement costs, with the railroad(s) paying back whatever fair share corresponds with operating improvements only over time. (Compare this with the discussions for transit systems that have initial very low farebox returns...)
Combined with some form of stop/start on the large diesel (is that possible) you could achieve the zero emissions.
It's a reasonable idea, but I strongly suspect that the appropriate amount of 'start/stop' would require extensive redesign of the starter and drive gearing for either an EMD or CB engine, and each restart would involve a certain amount of grossly inflated emissions until the engine reached stable rpm and heated properly. (Think of the problems that killed the working part of the GM 8-6-4 idea) In addition, it's largely power transitions that cause the usual sorts of emissions problems with diesels, and this is now a two-step process (starting and stabilization, then ramping up slo-o-o-owly to desired power) which rules out much of the potential 'zero-emission' gain you'd get in operating hump service.
To make it practical to start and stop a locomotive diesel repeatedly involves other things, too. I would presume that full prelubing, 'turbo timing', coolant tempering, intake charging and preheating, etc. were all provided, and that in particular any EGR would be fully filtered, perhaps even washed, before being reintroduced to the intake. Many of these things have been worked through by people operating 'preserved' locomotives in low-margin service (and described in some detail in posts on RyPN).
I would presume that a hump set really only needs both units when pushing.
My opinion would be a bit more drastic - a hump set needs all the traction motors making power when pushing, and needs few if any motors making power at other times. It's almost an ideal service for straight electric or high-storage battery-electric, with no more 'engine' than for charge sustaining or perhaps marginal acceleration for a few seconds at the peak of a shove, which is why I'm surprised that no one seems to have figured out how to optimize a genset design to produce appropriate performance. (Although after the "engineering" analysis that went into the Green Goats, I suppose little absence of proper engineering in that area should surprise me...)
For the record: a genset for flat switching (etc.) needs to have the option to fire up any number of engines predictively and proactively, so that they have stabilized and come up to power at the moment the locomotive is needed to pull. This whether or not there is substantial battery power available for 'hybrid' (as opposed to "plug-in") power. It is now possible to provide full intake-port pressure charging electrically for starting large truck engines with 'lower emissions', and nominal 72V electrical systems facilitate this even further -- whether that would help reliability is a more interesting and far less certain question. I would expect all the above considerations for large diesels to apply to 'converted' truck engines as well -- most certainly apply to the Navistar VT365 converted to run in light trucks, for instance, and that is far from what is demanded even in Class VIII OTR.
There are other things that could be done, and need to be done, with small prime movers in railroad service. Shock isolation and better telemetry come to mind fairly quickly. While there are advantages in using "OTS" engine technology adaptively, we should remember that adaptive reuse has clear emphasis on proper, and reliable, adaptation.
It issues with EGR even for us in the OTR industry is not the heating and cooling cycles the engines face. It comes down a combination of the Sulphuric acid the engines themselves create and even in the exhaust at full temp it is in there plus the particulate matter. The acid over time erodes the metal and the particulates flat out remove it also. It is like your sandblasting a part while spraying it with acid rain. The engine makers have yet to solve it and I doubt they can. About the only way they might would be to remove the sulphur from the fuel to solve the acid issue however your still left with the particulate matter. The issue with EGR is they grab it right from the exhaust manifold and then cool it then throw it back into the intake. You compound the acids and particulates in the exhaust and the amounts that go thru the cooler.
Shadow the Cats ownerIt comes down a combination of the Sulphuric acid the engines themselves create and even in the exhaust at full temp it is in there plus the particulate matter. The acid over time erodes the metal and the particulates flat out remove it also. It is like your sandblasting a part while spraying it with acid rain.
All this silly stuff was handled long ago ... or was supposed to have been; the engineering and the science certainly were, by the time I was in grad school (which is many, many years ago) and all you have to do is look at the research into Franco-Crosti preheaters (for the acid side) or BCR's coal turbine (for the very small part of PM that constitutes abrasion) for ancient history that handled the situation that would prevail in any OTR EGR cooler.
First, with low-sulfur fuel, there is not enough sulfur left to constitute extensive mass flow, and of that tiny percentage much of it burns only to the dioxide, which doesn't form sulfuric acid in the first place. A relatively small proportion of the small proportion does, in fact, go to SO3 ... but if you fall below the dew point of the acid anywhere in the actual EGR cooler you are throwing away heat energy, and so where you should expect the real acid-damage potential to be is in the intercooler, where any recirculated gas finally comes down to the point that liquid acid would be condensing on a surface.
Second, alloys that are highly resistant to sulfuric acid attack are well known, and the subset of these that are suitable for fabrication into typical kinds of EGR cooler are scarcely more arcane. If automotive engineers are too cheap or miseducated to get the materials science and fabrication right, there is a range of hard and/or conformal coatings that can be applied, either electrically or chemically bonded into the surface finish of the 'inside' of the cooler, which are either relatively immune to most of the generated PM or that possess enough resilience that impact by hard carbon will not abrade it (any more than hard carbon in a high-pressure air jet would abrade your hand).
The real problems (and you are observing them) are not to do with any fundamental science or engineering, or (really) with the recirculated-exhaust theories of NOx reduction. They have to do with how the EGR cooler is plumbed, and particularly with how and with what the exhaust to be recirculated is treated.
Yes, the acid situation needs to be addressed in large part by taking as much of the sulfur out as possible -- there are advanced methods in the refining industry for doing just that, a number of which were discussed in good detail during the runup to 'mandated' ULSD. In my (perhaps wrong) opinion, the increase in price when ULSD came in, which has never gotten lower as equipment and factor material production was costed-down, more than covers extracting or neutralizing effectively all the sulfur content in current OTR motor fuel. Also in my opinion, more attention needs to be paid to restoring the pre-ULSD lubricosity of the fuel so that people don't "have" to use Stanadyne or other nostrums to get their injection systems and whatnot to live better.
If you read the material from the EPA, current thinking is that sulfur-containing particles are a major nucleation source for PM in the 'danger range' (well under 100nm with an appropriate fractal dimension) so there is extra justification to go that extra mile to solve the issue even to the small extent existing ULSD left it open.
Meanwhile, the 'correct' way to implement EGR or FGR is to clean the gas of any, well, non-gas constituents before it goes into anything that can be abraded or corroded. So far, it isn't cost-effective to do this on Class VIII trucks, in part for the reasons given. But, as with things like coolant filters (which shouldn't ever be 'necessary' but certainly are on the Power Cerebrovascular Accidents) it may be desirable to implement some additional things to cut down on the observed problems. Look for more advanced (but not particularly more expensive) engine management systems to handle some of this; it isn't particularly difficult to run a diesel engine at very little opacity (which means very little visible PM, let alone the small proportion that might be abrasive to high-strength materials) merely with crankshaft-speed and combustion controls.
You would, as I've said, not want to drive such a thing without a fairly powerful hybrid energy-storage transmission; that's needed even to accelerate the engine against compression when doing a speed transition, let alone for typical driving which involves fairly frequent changing (even on what looks to the non-driving public like a straight level road in calm air) of gears up and down and accommodating engine speed. That latter is almost surely the root cause of most of your nonlinear problems...
It is easy to throw up the hands in horror and say 'look at the cost increase and mileage decrease!' By comparison we might gainfully look at the clean-coal industry (or at least the substantial part of it that wasn't a racket) -- if you want zero net CO2 emissions look for an increase in fuel mass of around 37% minimum. Same is true if additional space, weight, or inflexibility is mandated for trucks -- you'll accommodate, change loadouts accordingly, and bill the client cost-plus. As you've been noting over and over, there is little effective replacement for Class VIII trucks; in the long run everyone will put up and shut up just as they have until now, although perhaps a bit more stridently and with more Trump-like intermediate-term political 'consequences'.
The issue with EGR is they grab it right from the exhaust manifold and then cool it then throw it back into the intake. You compound the acids and particulates in the exhaust and the amounts that go thru the cooler.
Here is where I suspect the actual problems are reaching wreck proportions -- the people designing the cooler did not expect to see 6x recirculation of some components of the exhaust stream, and so may have cut corners in its detail design. The key, as I said earlier, is to provide effective separation of those elements from the gas on each recirculation 'pass' so that, at the very least, there is no cumulative increase in the troublesome components of PM. Acid is hygroscopic, so either there is not enough cooling or not enough separation; erikem could design you systems to solve the problem in his sleep, and he's not a vehicle engineer.
RME,. In road application, EGR is not plumbed through the intercooler. Unless you're referring to the EGR cooler of course.
Different on locomotives perhaps?
Also it seems like you're advocating for putting the EGR system downstream of the DPF system? Interesting but I don't see how that could be done in anything road sized. Even in locomotives I'd wager the heat from a regeneration process would be detrimental to the EGR cooler.
ruderunnerRME,. In road application, EGR is not plumbed through the intercooler. Unless you're referring to the EGR cooler of course. Different on locomotives perhaps?
I'm well aware where the recirculated gas is plumbed from ... and how coked up the ports and passages can become (depending on the type and design of particular engines). What I was referring to was the aspect STCO was mentioning: that the problems were related to multiple recirculating passes through the EGR cooler as the proportion of spent gas multiplied over time. (There are theories to increase EGR spent gas to the maximum percentage to reduce available nitrogen, including some that use molecular sieves (yes, at considerable size and typical operating pressure) to enrich oxygen in the proportion of what otherwise becomes makeup air at that point, but don't confuse that with existing approaches.) It would be one thing if the proportion of gas was passed through the intake, but it isn't; it comes repeatedly through the ports, and if I understand STCO correctly, both the acid concentration and the deleterious PM is recirculating in a way that increases it in key areas with the multiple passes. You will recognize the problem if any substantial level of boost, intercooled or otherwise, is used on the engine and its back pressure is applied on the flow from the ports, which is much more tortuous than the downpipe and other plumbing to the turbine; perhaps this is part of the syndrome.
I do not think she is lying about the problems with these engines; it follows that we have to figure out where the difficulties are coming in, and what can or should be done about them. I find it especially interesting that she is observing a 2-3 year timeframe for the problems to occur, but then apparently widespread and destructive consequences, but recently described a catastrophic failure in what I understood to be an almost-new engine.
Also it seems like you're advocating for putting the EGR system downstream of the DPF system? Interesting but I don't see how that could be done in anything road sized.
Actually I'm advocating for something even less easily done in something road-sized: removing particulates separately from the portion of extracted gas, as soon after it it tapped from the ports as possible, and removing at least as much 'acid' as possible before it reaches the parts of the EGR cooler proper that are suffering from irremediable corrosion. It would be nice to do this in some of the ways used for FGR, but I am well aware of the difficulties that would be involved in either packaging or running such a thing.
Why is there a failure in a brand new engine from time to time the only thing they can figure out is that the engines are running at the max allowed recirculation of exhaust for longer peroids. When we get the longest life is when an engine is run with the lowest amount of EGR possible when the EGR is cranked up to the max amount the EPA mandated to almost 30% of the exhaust amount that is when you see the fast failures. Think about it an engine trying to reburn 30% of the prior combustion gasses per charge adding more particulate and sulphur compounds to the exhaust and your then taking 30% of that right back into the engine.
We have had a few quality control issues in the industry the normal failure points are the EGR valves failing to close and the engine fails to set a code since the EPA mandated it only set a code if it fails to open. You have to love that one.
What your wanting to do remove the particulate matter and the acid compounds before they are recirulated is physically impossible. The exhaust is captured for recirulation before it even goes thru our turbocharging system they capture it that fast. They are capturing stuff at over 1300 degrees at the end of a long climb then cooling it with engine coolant in coolers to less than 200 degrees then slamming it into the intakes to be reused. Your wanting to add more equipment to fail onto the engines sure both industries will get right on board with that. Modern day engineers have forgotten the KISS principle or Keep It Simple Stupid. They think more complex is better for getting rid of the problems. We have an old truck it is an 84 KW we use it for a spotter to run and get trailers from town and bring them to our shop and yard complex for washouts or after their loaded for our drivers to take for their next delivery. Now this truck is an 84 has over 2 million miles on it It was overhauled 5 years ago at 1.7 million miles for the first time in its life. Why did we overhaul it then. We had to it broke a rocker arm and swallowed part of it. Total for all the parts according to the invoice I pulled was less than 6 grand. That was for all new pistons sleeves connecting rods pushrods rock arms new injectors and injection pump and bearings for both the crank and cam. I just authorized a repair on a 2013 truck being traded in next year that blew its SCR injection system. It cost us over 10 grand to fix that one system in parts alone.
Shadow the Cats ownerWe have had a few quality control issues in the industry the normal failure points are the EGR valves failing to close and the engine fails to set a code since the EPA mandated it only set a code if it fails to open. You have to love that one.
If I had to hazard a guess at this, I'd think that most of the failures are occurring not so much because of increased PM or 'acid' per se, but because of nominal overheating -- and I think you have accurately identified the culprit as being either the EGR valve itself or the system that is modulating it.
I suspect that there is no pyro at the 'hottest' point of the EGR passage, or just ahead of the EGR valve. Some combination of design, manufacturing tolerance or even surface finish/treatment, carbon, or heat distribution may cause that valve to stick in some position, perhaps when modulated 'too open' for 'too long' at WOT/high fueling at high load conditions. This would pass excessively hot gas at high mass flow through the EGR cooler, which may itself be suffering poor heat transfer due to selective deposits on the gas or the (now becoming degraded) coolant side. Unless the cooler is properly welded with proper transitions between 'shell' and 'tubes', that can easily produce mechanical separation or augmented stress corrosion cracking (I am assuming that your problems are primarily the latter and not the former!)
Correction of this, aside from redesigning the cooler or the EGR circuit for lower peak temps and/or selective filtering, would not involve more than a few extra sensors and the logic to 'sensor fuse' the results together. There are flowmeters that work with dirty and hot gas, but I'm not sure they'd hold up unattended for the required long time under indeterminate conditions; perhaps a better approach (since the flow is supposedly mapped in engine design or testing) is to put an extension sensor on the valve actuator so the degree of its opening can be accurately determined continuously. That combined with at least one upstream pyro would give you warning about the valve's operating state; a downstream pyro just ahead of the EGR cooler might give you warning that it may encounter excessive heating and SCC; a thermometer for the outlet gas would confirm effectiveness and some kind of sensor downstream of the EGR cooler that detects coolant constituents/vapor or a marker in the coolant would QUICKLY detect an exchanger failure, even a catastrophic one (and I suspect almost any SCC failure in an EGR cooler would be sequential starting with relatively small transudation). Note that most of this is an easy retrofit mechanically, and not much more difficult electrically even if you're wiring to one of the current busses. Logic is more of an issue, but at root any competent electronics hobbyist could cobble up a device that could coordinate the readings to produce an appropriate in-cab alert or flag.
Ironic that one of the fixes involves MORE unfunded EPA mandating -- 'setting a code' that the EGR is stuck. (Oddly enough I believe there are automotive codes that indicate the EGR is not 'modulating'; they set on a 6.0L when the valve is physically disconnected, but not when the EGR is bypassed with the usual O-ringed 'plug' and the valve is connected but left in some kind of packing (to keep it stable) on the adjacent manifold.) If we are talking EFFECTIVE use of the mandate, there should be a code for 'full open' and a code that indicates slow or defective following of the signal from the FADEC or whatever they call it now.
What is the code that is set for coolant in the bypass exhaust?
What is the code that is set for overtemperature at the EGR cooler inlet? Outlet?
What is the code that is set for 'inadequate mass flow through the EGR system', and how is it determined and processed?
How often is the COOLANT side of the EGR cooler flushed out, or borescoped for corrosion?
I see you're adding to the post as you go.
Shadow the Cats ownerWhat your wanting to do remove the particulate matter and the acid compounds before they are recirculated is physically impossible.
It is physically very easy. The problem is that the systems to do it 'right' or even 'effectively' are bulky and can't be easily mounted where existing EGR systems go: ending up right in the head casting or in the valley of a V-type engine, with small and short plumbing runs to the cooler. The real issue that ought to be the initial focus is bringing down the peak mass flow temperature going into the gas-to-coolant EGR cooler, which implies some sort of intermediate cooler that handles the peak temperature without degrading coolant or suffering overtemperature issues. This would be a logical time to do something about the stickier parts of the PM, or other components of the passage gas that may be condensing and then dribbling or coming loose in the passages as the temperature 'excurses' and differential to the cooled head (or transfer port walls or whatever) drops or fluctuates so it isn't what the engineers thought it would be in a nice clean dark port at stoich and steady-state operation at the fat peak of the powerband.
The exhaust is captured for recirculation before it even goes thru our turbocharging system they capture it that fast. They are capturing stuff at over 1300 degrees at the end of a long climb then cooling it with engine coolant in coolers to less than 200 degrees then slamming it into the intakes to be reused.
And that, as I noted, is a big piece of the problem, although I think 'slammed' is more than a little bit of an understatement; the gas pressure going into the EGR system can only be a few psi higher, at most, than that at the turbo inlet, and by the time it has worked its way through the tract to the EGR valve, the spool and ports of that valve, and all the tortuous twists and turns of the passages in the head(s) you are not likely to get much shockwave generation from the gas flow. You can calculate the maximum mass flow per cylinder quite effectively relative to displacement and CR (knowing the 30% maximum proportion and the commanded rpm of the engine) and I think you will agree that it's heat effects and not mass effects that are the most significant issues causing troubles.
Shadow the Cats ownerModern day engineers have forgotten the KISS principle or Keep It Simple Stupid. They think more complex is better for getting rid of the problems.
The problem is that sometimes you have to go to complicated to get simple operation -- think of a computer running assembler, or a PLC, compared with a Mac running OS X for multiphysics analysis. In this case more specific information, perhaps from redundant systems with no common failure mode, needs to be monitored -- continuously, during any power excursion out of 'normal' steady-state operation -- and a fast, specific set of responses and/or alerts needs to be generated. There is no rough and fast KISS setup that will give you that.
Of course I'm not defending needless complexity, any more than I'd defend unnecessary operations. Nor am I defending Mickey Mouse built-to-too-low-a-price implementations, or cases where engineers dropped the ball in determining actual failure modes or scenarios (as, in part, I think the case to be with these EGR coolers). But until Californians stop caring about air quality in sufficient numbers to throw out Nichols and her crew of fault-finding lawyers and wannabees, which I don't think will be any time soon, you will not be able to go back to simple closed-loop systems ... you've already argued compellingly that simpler effective EGR pretreatment is 'impossible' on these trucks.
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