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Modern diesel efficiency compared to first generation..

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Posted by Erik_Mag on Sunday, January 9, 2022 10:46 PM

Overmod

Coming up with a control algorithm that will adjust timing to accomodate changes in the circuit parameters. Examples include juncton temperature affecting rise and fall times, with corresponding changes required dead time. One difference between then and now is that real time processing power to do a cycle by cycle adjustment in timing is a lot more affordable now that back then. Another difference is using SiC or GaN FET's, nether of which have the turn off current tail from IGBT. The 300kW demo inverter uses USiC (now part of Qorvo) cascode JFET's.

I came across a similar situation with an H-bridge using SiC FETs, looking at the cicuit response while adjusting deadtime - saw that increasing deadtime a bit allowed the slightly inductive load to commutate the H-bridge - the "inductive current" would charge the output capacitance of the device that was turned off, and the other device in the totem pole could be turned on with zero voltage across it.

The reason why eliminating switching loss is a big deal is that otherwise the design would need to find a compromise between switching and conduction losses. Conduction losses can be reduced by going to a larger die, but that comes at the expense of increased Drain - Source capacitance, which then entails more energy each time a device switches. Eliminating switching losses also allows operation at a higher frequency, which makes fitering easier.

I'll have to pass the link to my son at Purdue as one of his housemates is working on Purdue's DC House. Yes, I did see the purdue.edu in the link...

The story of the commutating pole for inverters reminds of a story about high power low distortion class A + AB audio amplifier stage. When the engineer asked why he didn't patent it, he said the stage was prone to self-destruction without the VI limiter that he did patent.

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Posted by Overmod on Friday, January 7, 2022 3:26 PM
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Posted by Erik_Mag on Friday, January 7, 2022 12:13 AM

With respect to improving efficiency, I was reading a couple of articles about a company that is using a "commutating pole" to drastically reduce switching loss in inverters. They claim their prototype board is capable of achieving a peak of 99.5% efficiency in converting 600 to 800 VDC to three phase AC.

I've bolded the "switching loss" as the active devices (e.g. IGBT's, FET's, SiCFET's, GaNFET's, GTO's, etc) experience two kinds of loss. One is conduction loss, caused either by the voltage drop due to Rds_on in the various FET's or the VCE_ON for IGBT's and GTO's. The other loss is switching, with much of that loss involved in charging or discharging device capacitances and it what the new technology promises to drastically reduce with switched capacitance (this is not snake oil).

Note that the real benefit from increasing efficiency from 99% to 99.5% is not the savings in energy, but instead is in the reduction in heat that must removed by coolants.

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Posted by Overmod on Thursday, January 6, 2022 10:08 PM

Note that I put the word in quotes.  The current train management systems are 'smart' in the sense smart houses and smart bombs are.

And remember that the smart in 'whip-smart' has two meanings... Surprise

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Posted by jeffhergert on Wednesday, January 5, 2022 10:03 PM

Overmod

 

 
CSSHEGEWISCH

It would be interesting to see the overall fuel usage and efficiency figures on the variable horsepower Cv40-9i's (NR class) introduced by National Rail in Australia.

 

It appears that most of the recent work in Australia/New Zealand follows the theory that 'managed' trains best operate at sustained speed, directed via a 'smart' system like LEADER or TO -- that implies reasonably fast acceleration subject to pollution control, then modulation of power as needed to control speed.

 

What this does NOT do is control the engine governors in a consist to achieve the equivalent of restricted notch or excitation.  Instead it acts to keep some locomotives in the consist at high notch while near-idling the rest (see SmartConsist or Smart HPT) which is not what the three-stage derating system on the NDs apparently does.

 

First time I've heard LEADER or Trip Optimizer referred to as "smart" systems.  Definitely something you won't hear from anyone that uses them.

Jeff

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Posted by BaltACD on Wednesday, December 29, 2021 9:48 PM

Overmod
If we are deciding to compare overall locomotive efficiency against 'first generation' all the points you made are valid.

Intermediate improvements not explicitly mentioned are the introduction of traction alternators on nominally DC locomotives, the introduction of practical 'creep control' and other traction enhancement on DC motors, and the list of practical improvements in the dash-2 series for EMD and thd general improvements and QC in the late -8 and -9 GEs.

Not everything was forward.  We might examine 6000hp locomotives in North America, the wretched electronic implementation in the EMD 50-series, and the phenomenon that was the Republic Starships for the 'progress is not always forward' discussion corner.

Progress is rarely if ever a straight line.  Not every 'new' idea actually works the way it was intended to work.  Such is humanity and its path form the caves and savannas of 100K years ago.

A locomotive is much more than just the operation of its prime mover.

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Posted by Overmod on Wednesday, December 29, 2021 9:33 PM

If we are deciding to compare overall locomotive efficiency against 'first generation' all the points you made are valid.

Intermediate improvements not explicitly mentioned are the introduction of traction alternators on nominally DC locomotives, the introduction of practical 'creep control' and other traction enhancement on DC motors, and the list of practical improvements in the dash-2 series for EMD and thd general improvements and QC in the late -8 and -9 GEs.

Not everything was forward.  We might examine 6000hp locomotives in North America, the wretched electronic implementation in the EMD 50-series, and the phenomenon that was the Republic Starships for the 'progress is not always forward' discussion corner.

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Posted by Backshop on Wednesday, December 29, 2021 6:16 PM

Overmod

ns145, you are correct of course, but the thread is only on the efficiency improvements in the internal-combustion prime mover.

 

 

Not really.  The OP included the word "locomotive" in his question, so that would include more than the engine itself.

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Posted by Overmod on Wednesday, December 29, 2021 1:10 PM

ns145, you are correct of course, but the thread is only on the efficiency improvements in the internal-combustion prime mover.

 

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Posted by Backshop on Wednesday, December 29, 2021 11:20 AM

Yep.  I'm sure mechanical engineers and railroad engineers have entirely different sets of criteria.

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Posted by ns145 on Wednesday, December 29, 2021 10:18 AM

OM, I understand what you're saying, but at some point one would also have to consider the effect of other design changes to locomotives outside the prime mover on overall efficiency.  Current EMD/GE models, thanks to advances in wheel slip control, adhesion, and AC traction motors can get much more of the electrical current they generate to the rail to move tonnage.  Early 2nd generation models, such as the SD45 and GP40, had to derate themselves at maximum load at low speeds to avoid massive wheel slip.  I'm sure that early 1st generation models had even lower adhesion values and more primitive wheel slip controls.  Somehow all of this should get factored in, albeit with apples-to-apples comparsions between similar train types and operating speeds.   

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Posted by Overmod on Tuesday, December 28, 2021 1:43 PM

Before you get too far carried away with semantics, the thread is about locomotive prime-mover efficiency, not horsepower per ton mile, which implicitly includes train speed.  If you were to extend Iden's graph past 2015 I don't doubt you would see "improvements" in fuel consumption due to the new drag era of slower, longer trains, just as you see some of his anticipated gains from systems like LEADER and TO, or expanded use of distributed power.

That only incidentally involves higher efficiency in the diesel prime movers: for that, you'd need to invoke things like variable-vane or staged turbos, better EFI and what used to be called FADEC, better tribology and ring/bore friction reduction... and on the negative side, efficiency reductions related to such details as idiot EGR and DPFs that are 'cleaned' regeneratively.

I'm sure there will be papers in SAE somewhere about post-2012 discussions of heavy diesel combustion-engine efficiency.

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Posted by BaltACD on Monday, December 27, 2021 6:40 PM

timz
 
ns145
The presentation has everything to do with changes in the overall fuel efficiency of locomotives. 

"Overall fuel efficiency" meaning ton-miles per gallon of fuel. The report says nothing about horsepower-hours per gallon of fuel -- they couldn't measure that, of course. Apparently the average ton-mile is easier to produce now, because the locomotive's SFC (drawbar horsepower divided by fuel burn per hour) hasn't dropped by "close to 50%".

Work performed by unit of fuel is the only way for railroads to effectively measure economic fuel consumption.

Railroads don't measure how much fuel it takes to run light power down to the corner store for a gallon of milk and a pack of gum.

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Posted by timz on Monday, December 27, 2021 5:23 PM

ns145
The presentation has everything to do with changes in the overall fuel efficiency of locomotives.

"Overall fuel efficiency" meaning ton-miles per gallon of fuel. The report says nothing about horsepower-hours per gallon of fuel -- they couldn't measure that, of course. Apparently the average ton-mile is easier to produce now, because the locomotive's SFC (drawbar horsepower divided by fuel burn per hour) hasn't dropped by "close to 50%".

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Posted by ns145 on Monday, December 27, 2021 2:38 PM

timz

 

 
ns145
Close to 50% from 1965 to 2015 according to Michael Iden's presentation to Railtech: http://railtec.illinois.edu/wp/wp-content/uploads/pdf-archive/9.1.pdf

 

 That says nothing about the efficiency of the locomotive -- just the "efficiency" of the average train, based on ton-miles. The locomotive's SFC hasn't decreased by 50%.

 

 

The presentation has everything to do with changes in the overall fuel efficiency of locomotives.  I grant you, however, that it doesn't contain specific data on changes in the fuel efficiency of locomotive diesel prime movers.

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Posted by timz on Monday, December 27, 2021 1:29 PM

ns145
Close to 50% from 1965 to 2015 according to Michael Iden's presentation to Railtech: http://railtec.illinois.edu/wp/wp-content/uploads/pdf-archive/9.1.pdf

 That says nothing about the efficiency of the locomotive -- just the "efficiency" of the average train, based on ton-miles. The locomotive's SFC hasn't decreased by 50%.

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Posted by Overmod on Saturday, December 25, 2021 12:38 PM

Better watch out, though: Iden also includes a discussion of platooning (with favor) and considered the Arrowedge to be innovative out-of-the-box thinking (I consider it more out-of-their-minds thinking as things turned out...)

What is highly interesting is the virtual collapse of gallon-per-ton-mile consumption in the relevant graph (note the interesting little pip centered circa 1985) which really ought to be redrawn at much larger vertical scale with a commented timeline... hmmm, that might be the basis for a good Trains article.

Absent is a discussion of advances (and shortfalls!) in actual engine technology and pollution-control equipment.  While that might induce MEGO syndrome in conference attendees just as it does in forum posts, it would have been interesting to touch on.

As would the relative worthlessness of 'notch restriction' in actually conserving gal/ton-mile, or the actual big saving from running those PSR monstrains... interesting things have happened since ~2015.

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Posted by ns145 on Friday, December 24, 2021 5:32 PM

Close to 50% from 1965 to 2015 according to Michael Iden's presentation to Railtech: http://railtec.illinois.edu/wp/wp-content/uploads/pdf-archive/9.1.pdf

1965 corresponds very well with the start of mass deliveries of EMD's 645-powered 2nd generation locomotives.

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Posted by oltmannd on Friday, December 24, 2021 12:54 PM

I think 20-25% isa on the low side.  I'll have to do some digging.

 

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by Overmod on Wednesday, December 22, 2021 2:23 PM

Probably valuable to add that the SFC improvements would have been far more dramatic if pollution control were not also a concern.  One of the great advances was proportional EFI capable of multiple/pilot injection; another was eliminating the mechanical drag of the positive-displacement Roots blower at high engine rpm.

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Posted by bogie_engineer on Wednesday, December 22, 2021 10:30 AM

I would say from my experience at EMD it was continuous improvement in engine BSFC starting at about 0.4 lb/BHP-Hour for the roots blown 567 to close to 0.31 for a turbocharged 710, coupled with an ongoing pursuit of reducing parasitic accessory load of cooling fans and traction motor and generator blowers via multi-speed motors and lately variable speed drives. Larger radiators with more tubes and separate aftercooling allowed reduced fan HP and more efficient engine operation. 

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Posted by Backshop on Wednesday, December 22, 2021 7:33 AM

What makes newer locomotives more efficient, by far, are AC traction motors and computerized wheelslip technology.

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Posted by Overmod on Wednesday, December 22, 2021 1:10 AM

CSSHEGEWISCH

It would be interesting to see the overall fuel usage and efficiency figures on the variable horsepower Cv40-9i's (NR class) introduced by National Rail in Australia.

It appears that most of the recent work in Australia/New Zealand follows the theory that 'managed' trains best operate at sustained speed, directed via a 'smart' system like LEADER or TO -- that implies reasonably fast acceleration subject to pollution control, then modulation of power as needed to control speed.

What this does NOT do is control the engine governors in a consist to achieve the equivalent of restricted notch or excitation.  Instead it acts to keep some locomotives in the consist at high notch while near-idling the rest (see SmartConsist or Smart HPT) which is not what the three-stage derating system on the NDs apparently does.

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Posted by CSSHEGEWISCH on Tuesday, December 21, 2021 10:01 AM

It would be interesting to see the overall fuel usage and efficiency figures on the variable horsepower Cv40-9i's (NR class) introduced by National Rail in Australia.

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Posted by BaltACD on Tuesday, December 21, 2021 9:34 AM

The only real measure that the carriers look at it ton miles/gallon.  In territories where 1st Gen locomotives were rated at 1000 tons,  today's locomotives are rated North of 5000 tons per unit.

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Posted by rrnut282 on Tuesday, December 21, 2021 8:30 AM

timz

I'll guess 20-25%.

Al Krug's table is available on the Wayback Machine -- it says an F7 or SW1500 burned 93 gallons per hour in Run 8.

https://web.archive.org/web/20100529204212/http://www.alkrug.vcn.com/home.html

 

For context, the C44-9 burns 210 Gal/Hr so in a one-dimentional view, not an improvement. 

If you look at the HP per Gal/Hr, it tells a better story.  From the low of an E-8 at 12 HP/Gal/Hr to the C44-9 (about the newest locomotive with data on Al's page) at 20.9 HP/Gal/Hr a definite improvement over the years.  

Mike (2-8-2)
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Posted by Flintlock76 on Wednesday, December 15, 2021 11:30 AM

BaltACD
On CSX when I was working, trains were to be advised if they were going to be stopped for 30 minutes or more.  Crews were to shut down all engines except for the lead engine for fuel conservation. 

That's exactly what I'd see when I was doing some lunch-hour or slow-day railfanning at a favorite spot near the Richmond Amtrak station. (Old RF&P, now CSX)

Typically a diesel lash-up of three or four units stopped and waiting, the lead unit running but the trailing ones shut down.  It was pretty interesting to catch the start-ups too. 

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Posted by BaltACD on Tuesday, November 2, 2021 2:33 PM

SSW9389
Last month on my way to our 15th Cotton Belt Regional Railroad Symposium I encountered four southbound Union Pacific trains between Brinkley and Pine Bluff. Three were parked on the mainline with their crews staring at red blocks. The fourth was walking its train over the Arkansas River Bridge and into Pine Bluff Yard. It doesn't matter how a locomotive is built if it is standing still. Later at the Arkansas Railroad Museum a retired SSW/SP/UP hoghead told me that as long as the trains are parked it was considered running time and not dwell time. 

Ed in Kentucky 

I don't know UP rules concerning stopped trains on the Main Line.

On CSX when I was working, trains were to be advised if they were going to be stopped for 30 minutes or more.  Crews were to shut down all engines except for the lead engine for fuel conservation.  Crews were to be given adequate notice of when they were going to be moving again so they could get the shut down engines running and on line again - nominally about 10 minutes per unit (note - with 21st Century AC road locomotives - on CSX it was rare to have more than 3 units on line account head end horsepower restrictions.)  CSX didn't begin to utilize DPU's until after I retired, so I am not aware of how they are handling them.

Sitting in sidings or being held out of terminals is considered line of road delay, not terminal dwell.  When it comes to operating statistics there is always a 'game' being played between terminal management and line of road management, the game started once it was understood there were terminals and line of road.

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