Sorry, that answer doesn't help. But I was interested in that question and
thought that the first boat with a steam turbine was called "Turbina", But
I found this:
It's name was Turbinia, by Parson. But that doesn't help either.
Have a llok at
I remember as as schoolboy listening to reports from Le Mans as the Rover
turbine came past with the most distinctive whine.
As I rember the main problems were awful throttle lag - 3 seconds delay
between depressing the pedal and anything happening, and the problem of
getting rid of exhust heat.
Jet 1 was on display at the Science Museum for many years.
Doesn't answer the question but very evocative!
Well...as you scale things up and down the balance of forces changes,
but I suspect the turbine should always be more efficient with steam
because it is like a compound engine with each ring of blades being
like another cylinder. This means each ring of blades should settle at
a fairly fixed temperature and minimse the power-sapping condensation
that is associated with each cylinder of a steam engine, where
expansive working causes heating and cooling and hence condensation
(and hence the old curse that 'expansive working is expensive
I have no in-depth knowledge of these things, but I reckon that the
modern turbine is the ultimate extension of the compound engine with
as many compound cylinders as there are sets of turbine blades and
nothing like the amount of mechanical losses associated with having
very many cylinders. I was surpised to find in old texts on heat
engines just how much steam condensation impairs the efficiency of a
steam engine. Its not down to lagging, it down to expanive cooling.
I have been thinking that highly superheated steam through a flash
steam boiler might be the answer, as this is the route to getting high
temperature difference and hence theoretically high efficiency, but it
is tough on the materials on the engine. There are accounts of flash
steam engines in model boats glowing red - see the book "Experimetal
Flash Steam" for details.
No doubt other more experienced guys here will point out the error in
I haven't seen any figures, but those numbers feel reasonable. Bear in mind
that a 50hp steam turbine would be a tiny thing. In comparison, we have a
typical 8000 hp/7000rpm boiler feed pump turbine from a 600MW set in the shop
at the moment and the bladed part of its rotor is about 18" diameter by 3'
long. This is a turbine that normally runs in parallel with the IP turbine, so
has an inlet pressure of about 500 psi and exhaust pressure of about 100 psi.
There is a single row of main steam pressure blades for starting, they have
blade heights of about 1/4". This is a very small and not particularly
I don't have the answer to your question (any more than the other
respondents) but a few facts may help put things in perspective.
In the mid 90s (when I was involved as a consultant in the power
industry) the maximum thermal efficiency of very large coal-fired steam
turbine generating plants was around 36%. I doubt if this has increased
much. These large (say 100-200 MW per genset) stationary plants have
every advantage they could have - high temperature, high pressure, high
mass:surface area ratio, condensing etc. On general principles, any
smaller turbine plants will have lower efficiencies.
The theoretical maximum figure for a reciprocating steam engine on the
Rankine cycle, operating on 20 bar (290 psi) steam and 400 deg C
superheat, non-condensing, is 20.7%. On a condensing cycle, this rises
to 29.4%. It seems that even the best practical (full size) locomotive
designs do not achieve more than 90% of the maximum non-condensing
efficiency, and condensing only gives about 50% of the theoretical
benefit, making these figures say 19% and 23%. (Source: Andre Chapelon,
"La Locomotive a Vapeur", English edition, p 72.)
The typical overall thermal efficiencies of the very best entrants in
the IMLEC competition for miniature steam railway locomotives (as far as
memory serves, I'm not about to go find the reports) was in the region
For comparison, I have seen specifications for very large reciprocating
internal combustion engines with efficiencies of around 45%. The most
efficient heat engines I have seen are the latest combines cycle gas
turbine (CCGT) gensets, which combine a gas turbine and a steam turbine
operated from the gas turbine exhaust; these have efficiencies (at least
according to the manufacturers) of around 60%. The laws of
thermodynamics will not allow much further progress, unless someone can
make materials capable of operating at very much higher temperatures.
A note of caution, I am not entirely convinced these different sources
are comparing like with like - the Chapelon figures seem to be based on
a percentage of the heat content of the steam (i.e. ignoring boiler
losses). The power generation figures are though overall thermal
efficiencies (electrical energy output versus energy content of the coal
or gas fuel) as are, AIUI, the IMLEC figures.
As I say, this does not answer your question, but it may spur someone
else to add useful details.
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