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Fireless Locos

Posted by kyleborg 
Fireless Locos
June 26, 2020 02:44PM
Hi guys, Hope everyone is well during this crazy Covid time!

I'm just doing some research on Fireless (stored/accumulated steam) locos, and this bit of information has me tied.
Can someone help me figure out what this means?


Dr. Gilli of Henschel of Germany designed fireless steam locomotives with accumulators that initially held saturated water at over 1,000-psia at 545-deg F (69-bar at 285-deg C) and 542.6-Btu/lb. This steam fed into a 250-psia running tank that supplied the cylinders. To convert saturated water at this pressure to saturated steam required that an average of 738-Btu/lb (1511-KJ/Kg) of heat be extracted from the remaining liquid in the accumulator. This meant that some 62% of the saturated water was devoted to thermal energy storage while a maximum of 38% could be allocated to traction. An accumulator measuring 6-ft diameter by 20-ft long initially held 22,500-lb of saturated water and 5,000-Hp-hr total thermal energy when filled to 80% capacity, would yield 1,540-Hp-hr available for conversion to traction (at 20% cylinder efficiency). A 30-ft long accumulator would make 2300-Hp-hr available for conversion to traction.

1,540-Hp-hr available for conversion to traction (at 20% cylinder efficiency) means what, exactly?

Do I get "only" 1540 HP-hr to the wheels BECAUSE the cylinder is 20% efficient and no more?

Or do I start with 1540 HP-hr of steam and my wheels get 1/5 of that (308 HP-hr) because the cylinder converts only 20% of it (1540) to the wheels.?

Fireless locos have always appealed to me but their science is wack winking smiley

Thanks all

Edited 1 time(s). Last edit at 06/26/2020 11:17PM by kyleborg.

Re: Fireless Locos
June 26, 2020 09:10PM
The way I read it, the water in the boiler has 5,000 HP-Hr TOTAL stored energy in the form of saturated water. We can extract 38% of that, in the form of steam,which is 1,540 HP-Hr. Our engine can only convert the steam's thermal energy into mechanical efficiency at a rate of 20% (which seems way too optimistic for saturated steam). This seems to say that our total output is 308 HP-Hr.
Re: Fireless Locos
June 26, 2020 11:16PM
That's kind of how I took it to read. Thanks for your additional explanation.

But.... how on earth would a 30-ton fireless loco pulling a few rail cars get by with only 308 HP ? I've seen them pulling around 10-15 cars, which would weigh 200 tons empty!

In the trucking world, I can move a 40-ton max weight rig with 300 absolute minimum HP (500HP preferred), but it would move quite slowly.

Seems that stored steam and/or fireless locos are ridiculously inefficient.
Re: Fireless Locos
June 27, 2020 03:23AM
Running with steel wheels on steel rails needs much less effort than running with rubber tyres on a road surface - think of a shunting yard where the loco just give the truck a push and they roll freely for long distances - shoving a rubber tyred trailer on a level road would not do that.

Re: Fireless Locos
June 27, 2020 03:50AM
Also consider that horsepower is calculated as equalling (Torque X RPM) / 5252. So, that 308 horsepower can be generated at very low torque and high rpm or at very high torque and low rpm. A truck is designed to only develop just so much torque because there is a limit to its traction,, past a certain point the wheels just slip. A locomotive, being much heavier, can generate more torque without wheel slip.
Re: Fireless Locos
June 27, 2020 12:22PM
Thanks Mike Clark and Frustrated, the points you both brought up put things into perspective.
I've been watching video of fireless locos doing their jobs in various parts of Europe (getting rarer by the day) and I just wondered why someone couldn't make a car that used stored steam instead of a boiler. Obviously there would have to be a boiler at the owner's home, but that would be stationary and not nearly the headache of a "mobile" boiler. For the car, one just fills up with steam and goes, no startup routine required or the possibility of boiler explosions caused by inattention (a serious problem in 2020....).... anyways thanks guys. Steam rules!
Re: Fireless Locos
June 28, 2020 03:52AM
I think liqiud air or liquid nitrogen would a better option than steam for a stored energy device - I'd much rather have a tank of either in my garage than a steam generator - although not so much fun!

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