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Tier 4 VS Tier 3 Fuel Efficiency

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Posted by Overmod on Saturday, June 20, 2020 3:12 PM

Shadow the Cats owner
So most locomotives the Diesel Filter would be about 108 Grand to replace when required. 

I believe (and David Goding can comment with more specific knowledge) that locomotive DPFs are modular, probably sourced around units common to large Class 8 truck size.  That might make the aggregate cost go up, compared to the equivalent in a single can, but might also make it go down as economies of scale would make single large filters for a restricted number of locomotive applications more expensive than units built for a shared mandatory market.

Of course the DPF is largely a feel-good solution based on obsolete consderations of the 'social problem' with PM.  Essentially all the nanoparticulates that pose the actual danger sweep through a DPF as if it weren't there, even after the filter matrix has become substantially plugged with what is chemically similar to activated carbon.  Interestingly enough as it develops at least some types of GDI engine also produce nanoparticulates in the critical size range, something I think will be trotted out with appropriate miming of horror in the future when agendas are formed and have to be met.

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Posted by Shadow the Cats owner on Saturday, June 20, 2020 4:02 PM

The DPF is based on the size of the engine and you can not have a modular one as if you do it requires seperate fuel lines to it for the regens seperate power supplies for the heater for the regens and seperate heat sheilds for each one as you do not want a dozen 1500 degree boxed spread out all over the engine.  Your best bet is one spot for everything.  

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Posted by Erik_Mag on Saturday, June 20, 2020 4:57 PM

Overmod

Interestingly enough as it develops at least some types of GDI engine also produce nanoparticulates in the critical size range, something I think will be trotted out with appropriate miming of horror in the future when agendas are formed and have to be met.

From my understanding, GDI engines often produce an even higher amount of nanoparticles per horsepower hour than diesel engines. OTOH, there has been some interesting work at Sandia about "Bunsen Burner" inspired diesel injectors, i.e. using a tube to make sure the air and fuel were better mixed before ignition started. They're claiming reduction in both PM and NOx from better combustion control. What remains to be seen is how well this idea works in a real world engine.

A similar issue is pm from old jet engines, the J79's were imfamous for producing a lot of black smoke.

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Posted by Overmod on Saturday, June 20, 2020 5:51 PM

Erik_Mag
From my understanding, GDI engines often produce an even higher amount of nanoparticles per horsepower hour than diesel engines.

The principal issue, I think, is quench at very high rotational speed when very small injected charge (VW claimed to get this reliably down to the 35,000 fuel molecule per injection range, the only specific number I've seen) with air metering near theoretical stoich and wall quench.  The fuel droplets burn off hydrogen selectively but complete carbon oxidation does not complete in the short combustion interval.  This is different from sooting where there is either overfueling for the available oxygen (as seen elsewhere in Alcos and in 'rolling coal') or improper injection conditions that leave fuel only partly burned (most of the hydrogen comes off, but some remains or recombines in new combinations in what are usually coarser droplets.

In my opinion the only real solution to nanoparticulate soot is to expose it to adequate oxygen and promotion while it is still hot enough to react fully.  

At Princeton there was a group, back in the 'obligate carburetor days' before cheap ubiquitous microelectronics and piezos made individual GDI or even port injection cost-effective, that experimented with extreme lean-burn by charging the fuel and the jets up to over 35kV (so the fuel spray particles would self-repel).  This was the first place I saw insulative ceramic coatings used inside IC engines, before Ford experimented with them as thermal-barrier coatings in a different context, and some of the Polimotor research (if I remember correctly) provided similar self-charging repulsion in cylinder walls and chambers.  You could perhaps accomplish better assured atomization this way ... although I thought it was mad science coupled with a little lack of common sense to use high voltage around gasoline in a vehicle slated for typical American maintenance practices...

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Posted by daveklepper on Sunday, October 25, 2020 5:49 AM

I'm booting up this old thread, istead of starting a new one, because allthe "Tiers" relate to air-polution.  Locomotives got regulazted only after Auto Regulation had some success.  The following URL leads to atory about an important component in that success, which will interest most readers:

https://alum.mit.edu/slice/lessons-clean-air-car-race-50-years-later

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Posted by Leo_Ames on Sunday, October 25, 2020 10:34 AM

Any thoughts on Norfolk Southern's GP34ECO that's now being tested, Bogie Engineer? Looks like a much more compact installation this time around (albeit with a smaller 12-710) than a tier 4 710-powered SD70ACe would've required back in the early 2010's.

I'm curious with projects like this, if they've improved the fuel burn rate compared to your stillborn project? Interlake Steamship for instance is building America's first Great Lakes freighter in over 35 years using a pair of Tier 4 certified 16-710's for her engine installation.

Has EMD/Progress perhaps been able to tone down how much EGR would be needed today compared to a decade ago, enabling competitive fuel consumption? Or was that only a problem had EMD pursued a 710 powered tier 4 SD70ACe without DEF?

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Posted by bogie_engineer on Sunday, October 25, 2020 2:43 PM

Leo_Ames

Any thoughts on Norfolk Southern's GP34ECO that's now being tested, Bogie Engineer? Looks like a much more compact installation this time around (albeit with a smaller 12-710) than a tier 4 710-powered SD70ACe would've required back in the early 2010's.

I'm curious with projects like this, if they've improved the fuel burn rate compared to your stillborn project? Interlake Steamship for instance is building America's first Great Lakes freighter in over 35 years using a pair of Tier 4 certified 16-710's for her engine installation.

Has EMD/Progress perhaps been able to tone down how much EGR would be needed today compared to a decade ago, enabling competitive fuel consumption? Or was that only a problem had EMD pursued a 710 powered tier 4 SD70ACe without DEF?

 

 
It's been 5 years since I worked at EMD and I'm not connected to anyone on the engine side of engineering so don't know any specifics of this installation. The only thing I've seen online is that it uses DEF but see no mention of oxidation catalyst or particulate filter that was part of the system I was designing the loco around in 2011. With age, the equipment should get smaller and appears to have based on the loco pictures. I'm guessing it has no or minimal EGR since there doesn't seem to be a spot for the big roots blower and cooler of the previous 12-710 arrangement done for UP about 10 years ago. A big question to me is what injection system it has; if it has the common rail system as on the Tier 4 1010J, the hit on fuel economy compared to a Tier 3 710 may not be great. The extra back pressure of the SCR would hurt economy but the improvement of common rail and whatever they've done to the turbo may largely offset it. But it's all a guess for me as I really don't know.
 
Perhaps if this is a success, they may work on a 16 cyl version if the aversion to DEF on the freight railroads can be overcome. 
 
Dave

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