It occurs to me that part of the problem with evolving the 710 two stroke is its forced induction .
Most of the more current 'Kleen" diesels use more and smaller turbochargers . It makes sense as you get to take more advantage of the pulse energy and heat in gas retention than you would with a single turbo 710 EMD .
And then there's the need for a two stroke to have the blower effect just to make it start and run . EMDs system of driving essentially an exhaust driven turbocharger off the timing gears gear train is a brilliant idea but , it would be a nightmare attempting to drive two or four turbos in the same way .
Four strokes are far easier to drive (power) multiple turbochargers because there is no direct connection to their turbines .
Moving fiorward none of the compliant engines is going to be as simple as the outgoing crop of locomotive diesels . Really what they need to be is the most efficient piston pump they can come up with , and then add forced induction - plus all the emissions crap . For me it's not difficult to see where newer units like the QSK make the emissions grade more easily . They are literally designed to be in a "higher" state of tune than say a 710/FDL/Evo GE . If you want to compare it to car engines take a look at the first quad cam Corvette way back when . Far more complex than a pushrod lump of dinosaur - and a more intensive maint regime too . A cast iron 350 Chev with a carburettor and point breaker distributor may seem quaint , but it's going to need a lot more than add blue to get anywhere near 2015 emissions compliance .
I reckon your US operators are right to Tier 3/AC all the old power they can lay their hands on , and get them done as quickly as possible . These won't last forever but they will buy time before the late model garbage is the only thing they can legally run .
It's no surprise that most or all of the SD70ACe-T4s and ET44ACs are taking pride of place in Rotten Row roads .
Someone once told me (not an EMD person) that one reason for the difficulty meeting Tier 4 with 710 and GEVO engines is the 950-1100 rpm top speed of those engines compared to the QSK and C175 1,800 rpm engines. The time in the combustion cycle for the slower engines gives the NOx more time to form so more is produced. I'm not an engine specialist so don't know how much truth there is to that but it sounds plausible.
It will be interesting to see long term how durable the 1,800 rpm engines are in locomotive service.
Dave
Turbocharged delivery of scavenge air on two-strokes has been a non-issue for at least the past few years, and will go 'upside-down' as a cost-benefit concern over mechanical supercharging (whether with positive-displacement Roots or centrifugal blowing) soon if not already.
All that is required to replace the expensive and relatively fragile EMD arrangement with the gears and overrunning clutch is suitable motor-generator application on the turbocharger shaft, something extensively researched both for emissions and energy recovery in motor vehicles. Once the equipment is provided as OTS assemblies and components at locomotive size, even a mild amount of modern 'battery', far short of that for hybrid propulsion, easily accommodates all considerations of optimal scavenge at any governed notch rpm/rack or injection metering, as well as effective elimination of any meaningful concern about turbo lag.
Dave:
The shorter residence time for the QSK versus the 710 makes sense with repsect to lower NOx production in the QSK.
OM:
An exhaust gas driven alternator with a motor driven compressor sure sounds like a modern day Wright Turbo-Compound. One advantage is that any excess power from the EGT driven alternator could then be used for traction or auxiliary power.
FWIW, the reason Wright went with the turbo compound design was that it needed less weight than getting the same power increase by turbocharging.
D.Carleton jeffhergert They have been running back and forth between Proviso (Chicago) and North Platte, usually on manifest trains MPRNP/MNPPR. They were kept together until March 9th. That day the 9530 was set out at Marshalltown for an extra manifest when a scheduled engine to that train failed. Since then they've been apart, but usuall on the aforementioned trains. KLW people weren't happy about splitting them up, but not enough to press for them to be reunited. I was on the second crew on the extra manifest. I've had the 9530 a couple of times. That first time it was causing some electrical problems. Enough we had to get another engine before we could do a scheduled pick up of cars. UP rates it about half of a comparable EMD or GE. It was (and still does the other times I've had it ) give a wheel slip warning, but it seems to be a false warning. The other times I"ve had it (other than the wheel slip warning) there's been no problems. Jeff Thank you for that. The 9530 has been repowreed with a Cummins QSK95. But does she still have a Siemens traction system or something else?
jeffhergert They have been running back and forth between Proviso (Chicago) and North Platte, usually on manifest trains MPRNP/MNPPR. They were kept together until March 9th. That day the 9530 was set out at Marshalltown for an extra manifest when a scheduled engine to that train failed. Since then they've been apart, but usuall on the aforementioned trains. KLW people weren't happy about splitting them up, but not enough to press for them to be reunited. I was on the second crew on the extra manifest. I've had the 9530 a couple of times. That first time it was causing some electrical problems. Enough we had to get another engine before we could do a scheduled pick up of cars. UP rates it about half of a comparable EMD or GE. It was (and still does the other times I've had it ) give a wheel slip warning, but it seems to be a false warning. The other times I"ve had it (other than the wheel slip warning) there's been no problems. Jeff
Since then they've been apart, but usuall on the aforementioned trains. KLW people weren't happy about splitting them up, but not enough to press for them to be reunited.
I was on the second crew on the extra manifest. I've had the 9530 a couple of times. That first time it was causing some electrical problems. Enough we had to get another engine before we could do a scheduled pick up of cars. UP rates it about half of a comparable EMD or GE. It was (and still does the other times I've had it ) give a wheel slip warning, but it seems to be a false warning.
The other times I"ve had it (other than the wheel slip warning) there's been no problems.
Jeff
Thank you for that. The 9530 has been repowreed with a Cummins QSK95. But does she still have a Siemens traction system or something else?
I think it still has the Siemens system. I heard from another that one of them was testing a traction system, although I didn't hear the name.
bogie_engineer Someone once told me (not an EMD person) that one reason for the difficulty meeting Tier 4 with 710 and GEVO engines is the 950-1100 rpm top speed of those engines compared to the QSK and C175 1,800 rpm engines. The time in the combustion cycle for the slower engines gives the NOx more time to form so more is produced. I'm not an engine specialist so don't know how much truth there is to that but it sounds plausible. It will be interesting to see long term how durable the 1,800 rpm engines are in locomotive service. Dave
Editor Emeritus, This Week at Amtrak
jeffhergertI think it still has the Siemens system. I heard from another that one of them was testing a traction system, although I didn't hear the name. Jeff
D.Carleton I was with the Chargers for six years from just after testing at TTC, through commissioning and service until retiring last year. The QSK95 is built like a Swiss watch. That's the good news. The bad news: it's not railroader proof.
I was with the Chargers for six years from just after testing at TTC, through commissioning and service until retiring last year. The QSK95 is built like a Swiss watch. That's the good news. The bad news: it's not railroader proof.
You make them sound a bit like the German diesel-hydraulic units that SP and Rio Grande tried all those years ago.
Greetings from Alberta
-an Articulate Malcontent
SD70Dude I was with the Chargers for six years from just after testing at TTC, through commissioning and service until retiring last year. The QSK95 is built like a Swiss watch. That's the good news. The bad news: it's not railroader proof. You make them sound a bit like the German diesel-hydraulic units that SP and Rio Grande tried all those years ago.
Consider why the Chargers, with QSK power, are successful in the marketplace where the EMD/Progress Spirit with Cat engine decidedly hasn't been.
One of the subtle points about why the large Cat engines never seemed to be adopted by railroads for very long was that, if you did not carefully and expensively maintain them to factory specs, they could be prone to showstopping behavior like crankcase explosions. Where the engines receive diligent 'enough' attention, as in the NJT ALP dual-powers, they seem to run fine in what is now very extended and frequent service.
By contrast, the America-Loks were a maintenance disaster whether or not you gave them the care and attention. Every 30 days, flush and refill not only the torque-converter fluid but all the expensive-spec oil in the final drives. Reversing done with comparatively fragile motor-driven mechanisms, with the same very strong warning about not engaging the torque converter with any continued roll, making switching both excruciating and something of a crapshoot as to how long you could go without a surprise. SP apparently got to the point that KMs went out with an F7 that could recover the unit when it went down.
And then there is the issue that if the wheels weren't regularly turned to a common diameter, components in the Cardan shafting or even gearing could suffer damage, or the smaller wheels would be much more prone to slip... and reduce their diameter still further. (As I recall, this bit the Alco-Haulics too.)
Discussing EMD 710 vs. QSK.
The QSK gets to T4 using SCR with DEF.
So what is the point of the discussion vs. 710? EMD spent their engineering time trying to get 710 to T4 using NOT SCR and DEF.
That's comparing apples and Oranges.
The question is, how long did it take EMD to get the 710 to T4 with DEF for Railroad use? And that number should be in Engineer-Hours not calendar time. I suspect The answer is not very long.
The real question is when did they start and when did they really market it.
QSK succeeds in it's main application, the Siemens Passenger diesels, because the maintaince is handled at a very minimal number of places with minimal personel and please correct me if I'm wrong, but is not the engine smaller then a 710 at equivalent output? Certainly something to consider on a B-B locomotive.
I think the point is that EMD/whatever were trying to save their business and their last ditch effort was the 1010J four stroke EGR dead end .
To me the logical way forward is SCR/DEF , but the captive US rail road market said nope forget DEF . Their (operators) only saving grace was the loop hole that allowed earlier power to be "upgraded" to T3 spec . You have/had so many usable cores like Dash 9s and SD70s/90s that the financial reality has been T3 clones .
If an acceptable way can be found to have an upgrade path to T4 compliant current engines then this process may continue . Your operators clearly want to resist DEF and the associated infrastructure but it remains to be seen how long they can hold out . At the end of the day the late high speed diesels will need it anyway but fitting them to everything could be exy .
The process of upgading to T3 specs is probably doing more to clean the air than the imposition of T4 specs on new locomotives. What the folks at the EPA din't get is that tighter emissions limits only help if the RR's buy new locomotives to replace old ones, and the RR's aren't going to do that if the new locomotives are significantly more expensive to run than old locomotives.
I'd wonder if the ultimate solution would be gas turbines with some sort of bottoming cycle (supercritical CO2???) with batteries to enable running the turbines at full tilt or shut down.
BDA I think the point is that EMD/whatever were trying to save their business and their last ditch effort was the 1010J four stroke EGR dead end .
This completely ignores the corporate situation with EMD as it transitioned from GM to Greenbreir to Caterpillar/Progress.
You lay the blame at the 710, but the problem was, at least from what I've read, less about what the engineers thought made sense and more about what the various corporate masters wanted.
For a last ditch effort, the 1010J is a remarkable engine. ...but that's because it wasn't a last ditch effort. Engineering on the 265H wasn't zero and Caterpillar chose to spend the money Greenbrier and GM wouldn't.
There's ultimately 2 issues here. The corporate issue which was that EMD did not have the freedom (money) to do what GE did.
The second issue is what North American Railroads demanded of them.
Erik_MagI'd wonder if the ultimate solution would be gas turbines with some sort of bottoming cycle (supercritical CO2???) with batteries to enable running the turbines at full tilt or shutdown.
"Running turbines at full tilt or shutdown" is a nonstarting option. You'd need turning gear combined with shock protection while hot. If that fails once, there goes your big savings. You'll run the turbines no lower than the minimum effective rate for the hybrid transmission, and do the same thing hybrid automobiles do to balance battery and generated electricity at high demand. Then adapt the Carnegie-Mellon GPS/GIS integration to 'know' what demand will be over the prospective few minutes to regulate the turbine(s).
In order to do supercritical CO2 recovery, you need considerable free plenum space after the exhaust... at well over 700psi... with enough travel or means to pull the nucleate-condensing CO2 out of the gas stream before it goes to HRSG. Look at what the compressor of a turboshaft machine would have to develop if the low side remains at supercritical pressure... then figure out what your TIT is going to be even with "reverse recuperation" to cool the air down to be manageable.
Small turbine gensets may have some of the same issues as Green Goats, if they are of comparable (~200shp) size. On the flip side 'turning gear' for such turboalternators is likely to be easy to implement by motoring windings in the alternator appropriately.
One of the alternatives for the high-speed service I was working on in the mid-Seventies was a war-weary E unit on high-speed trucks, front packed full of PT6 or similar turboalternators, with a pan and electrical gear in the back end. The turbines were going to have all their connections modular, in lockable racks, so that any unit could be swapped out in the minimum number of minutes without taking the unit as a whole out of service. After 1973 that was really as much a giant sucking sound as anything else with turbines for high speed... but it was still a reasonably practical alternative technology.
I don't hesitate in recommending that piston engines be used for anything that might spend time running at ~34% efficiency or lower turndown, if you want to retain combustion engines, or that we go to effective hydrogen-fuel-cell/battery consists if the "zero carbon" boondoggle gets established. Not that I'd object to see someone try using a modern ceramic turbine, perhaps with magnetic bearings, in an attempt at a practical working locomotive...
YoHo1975 This completely ignores the corporate situation with EMD as it transitioned from GM to Greenbreir to Caterpillar/Progress. You lay the blame at the 710, but the problem was, at least from what I've read, less about what the engineers thought made sense and more about what the various corporate masters wanted. For a last ditch effort, the 1010J is a remarkable engine. ...but that's because it wasn't a last ditch effort. Engineering on the 265H wasn't zero and Caterpillar chose to spend the money Greenbrier and GM wouldn't. There's ultimately 2 issues here. The corporate issue which was that EMD did not have the freedom (money) to do what GE did. The second issue is what North American Railroads demanded of them.
I retired from EMD in 2005 when GM sold but was brought back as a contract engineer in August, 2010 (on the day Progress Rail took over from Greenbrier) to develop a workable locomotive arrangement to package a 710 with SCR, DOC, and DPF. Engine design engineers had been working on this option for some time before I joined in as the only way to make the 710 competitive re fuel economy having done work in parallel with massive EGR that they knew would create a big hit to fuel economy. You can see the first pass locomotive design and the unbelievable size of the aftertreatment system sitting over the engine here: https://www.flickr.com/photos/167589084@N07/albums/72177720297563787/with/51956544163/ Note the engine oil pan was extended to hold the alternator and assembly was on rubber isolators from the underframe. The aftertreatment package forced the engine to be recessed into the underframe by about 11", necessitating an integrated fuel tank.
I believe it was about mid-2011 when the edict came from the RR's about no DEF. That was the point at which discussion of taking the basic design of the 265H to create the 1010J began. Caterpillar sent some engine engineers to consult on the design but no design work was done by them, it was all by EMD engineers. This was a complete redesign of the cast crankcase to move the turbos from the rear to the front of the engine, making a compound turbo system, mounting the alternator to the crankcase and putting it all on isolation mounts among other changes. The locomotive design with the 1010J was paused while the Engine group designed the new engine and I left the project to develop new truck designs, the GBB span bolster four axle truck used in Brazil on the SD70ACe-BB and the HTCR-6 fabricated frame truck used on the Tier 4 loco.
One issue with using a High Speed Diesel vs Medium Speed Diesel is overhaul interval. A QSK would require a overhaul after 650K-700K Miles in service. A 710, GEVO, etc. only requires an overhaul at 1.2M-1.5M miles.. I highly doubt railroads want a prime mover that requires two in the span of one MSD.
Overmod "Running turbines at full tilt or shutdown" is a nonstarting option. You'd need turning gear combined with shock protection while hot. If that fails once, there goes your big savings.
"Running turbines at full tilt or shutdown" is a nonstarting option. You'd need turning gear combined with shock protection while hot. If that fails once, there goes your big savings.
One thing I know about combustion turbines is that they don't like too many start/stop cycles, so the battery would need to be big enough that the turbine would be running for at least an hour or more for every start. This should also allow time for the turbine to ramp down - perhaps by using the alternator as a motor during the spool down process. Starting is another area where using the alternator as a beefy starter motor would allow start of fuel flow and ignition at a much higher RPM than say aircraft, thereby reducing hot start issues.
Having multiple turbines would allow for running the turbines at full output when they are running.
Supercritical CO2 was one possible bottoming cycle, there's been some interesting work on thermo-electrics that may or may not pan out. One advantage of any bottoming cycle is a reduction in exhaust gas temperature.
On using an alternator as a motor - with the appropriate variable frequency drive and supply for the field windings, just abuot any alternator can be made to work as a motor. Many variable frequency drives work just as well operating as a "rectifier" as an inverter, using MOSFET switches can be more efficient than using diodes.
TACs were (I thought) a promising approach to electrical energy recovery a few years ago -- I actually have, somewhere, a technical presentation on DVD-R about one type...
The first concern about TACs is that their output is inherently high-voltage, like a piezo igniter, which is NOT advantageous if your energy storage includes current supercapacitors, which are definitively very low-voltage devices. The second concern is that, to get any cumulative current capability out of them, you need a great many devices operating across a temperature differential, which means a complicated arrangement of heat pipes or a great many devices arranged with heat on one 'side' and cooling on the other.
A VFD drive would be used to 'motor' a turboalternator because the turning gear even on a small machine would not require more than a fractional rpm to keep things straight. It's possible that this could be executed with the magnetic bearings turned off, a further saving.
It was my impression that a Brayton-cycle turbine is even worse than a diesel engine in terms of the 'compressing power' necessary to keep the engine running at idle. In the bad old days of early turboshafts that might involve 80% of the turbine developed power just to run the compressor. If you went to a split design with electric assistance on the compressor, you could likely manage high turndown for the power turbine, but oh brother you'd better have a large and correctly-designed energy storage battery arrangement...
Overmod It was my impression that a Brayton-cycle turbine is even worse than a diesel engine in terms of the 'compressing power' necessary to keep the engine running at idle.
It was my impression that a Brayton-cycle turbine is even worse than a diesel engine in terms of the 'compressing power' necessary to keep the engine running at idle.
The 4,500HP GE GTEL's consumed 450 gal/hr at full output ad 200 gal/hr at idle. Admittedly, this is the early days of gas turbine technology, but the 200 gal/hr at idle is about what a modern 4,400HP diesel engine consumes at run 8.
The two major advances in gas turbine technology have been the increase in turbine inlet temperature made possible by advances in metallurgy and improvements in isentropic efficiency of the compressors. There's probably a bit more that can be squeezed out with ceramic turbine blades and further imrovements in compressor design.
I'm assuming TAC's refer to thermo-acoustic converters using piezoelectric devices for converting acoustic to electrical energy. My comment on thermo-electric was using P/N junctions (i.e. Peltier coolers run in reverse) with improved materials - with the ideal material being a good thermal insulator but a reasonable electrical conductor. This would be a low voltage/high current source.
The simplest "bottoming cycle" would be steam injection using exhaust heat.
The problem with thermocouple junctions to make power is that there have to be an awful lot of them to make current at the (materials-specified) voltage. That means sticking a lot of insulating plates or vanes in the exhaust tract and studding them with junctions; up to now the cost-benefit of that sort of arrangement hasn't been sufficient (vs. even simple HRSGs with sufficient feed-train recovery to get gas temperatures well below 212F)
The place to inject steam, imho, is at about the same point as in a modern multipass boiler, and with the same bottoming concern: on a turbine you'd introduce the steam via throttling nozzles at some of the later compressor stages, to control NOx and 'carbureted' fuel flow in the burners and provide additional fully-superheated mass to drive the turbines. You would then recover both the injected and combustion water in the HRSG train (as above).
In my opinion, keeping the exhaust supercritical for CO2 sticks a pin in steam injection, as it either requires high pressure or some kind of mechanical feed pump and atomization that can produce the same effect with the appropriate degree of nominal superheat. The BFP arrangement on the enginion AG/ZEE engine is one example of an arrangement that could accomplish this -- but whether that would be cost-effective is a different story.
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