Steam & Excursion > Thermal Efficiency

A question for those in the know - Wes Camp, Hot Water, Larry Doyle, Frisco 1522, et al. I’ve read that a modern, late 40’s era steam locomotive had a thermal efficiency of roughly 5-6%. If a 2020 era engineer started with a clean sheet of paper, could that number be improved through modern materials and technology or do we have to file this inefficiency in the “it is what it is” drawer? Thanks in advance for any opinions.

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Edited 2 time(s). Last edit at 08/10/20 13:51 by Goalieman.

At times they could push up to 9% thermal efficiency....
about on par with current Nuclear Power industry ....

The biggest challenge with steamers was the high costs of underutilization 
and the layers of many craft unions.  
The diesel era allowed many steam-crafts to not be needed.

And diesels sit around, unattended, way easier than steamers.
A diesel will run, unattended, until the fuel is gone ....

So, with a steamer, the energy released in the firebox can be measured ( in Watts or Joules)
and the energy produced at the tender drawbar can be measured...  the difference when plugged into 
the equation is the "thermal efficiency".

Superheated operation was about a 50% increase in thermal efficiency, over
'saturated' engines --- we call the 'soakers'... they slobber so much condensate..
  
​W.

wcamp1472 Wrote:
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> At times they could push up to 9% thermal
> efficiency....
> about on par with current Nuclear Power industry
> ....

Sources I've seen talk of nuclear power being up in the 33% efficiency area... 

For what it's worth, regardless of "thermal efficiency", the absolutely best, most modern steam locomotive, was barely 10% officiant at the rail, i.e. the rear coupler. The early diesel electric freight locomotives, such as the EMC FT, where over 30% efficient at the rail (rear coupler of a 5400HP A-B-B-A set). Thus the marketing slogan of "Twice the Work at Half the Cost".

Depends on BWR or PWR, but some push 36%.  That's Gross MWe.  If factoring for the Net, it's a little lower.

The only number I've found put out with regards to coal fired, in lots of searching is 31.7%.  Combined cycle gas plants can push high 50s-low 60s.

Dan

exhaustED Wrote:
-------------------------------------------------------
> wcamp1472 Wrote:
> --------------------------------------------------
> -----
> > At times they could push up to 9% thermal
> > efficiency....
> > about on par with current Nuclear Power
> industry
> > ....
>
> Sources I've seen talk of nuclear power being up
> in the 33% efficiency area... 

Non-condensing steam engines, like almost all locomotives have a huge loss of thermal energy with the escape of the expanded steam and it's related heat energy.
Steam in closed, condensing systems such as steam turbine powered ships and electrical genarating plans, capture a lot of that heat.
When I learned this fact as a freshman in college physics, railfan magazines were full of speculation about how a well-designed steam engine could still beat diesels.
But from then on (very early 11960s) I knew it was over for steam as anything but a recreational thing.
That said I am glad to have seen and ridden behind a fair number of them.
Be real happy if you can get better than 8% or so.

Grateful to everyone for your thoughts and expertise. Appreciate you!!

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