Miles per Gallon (Litre etc.)

[malcolmd]

I am in the planning stages of a steam boat project, and am in need of some facts on fuel consumption of boilers.. I am building Leak Compound for a 27ft launch, and am planning on fitting a Yarrow WT Boiler... I was planning on liquid fueling this (diesel), but not sure what likely fuel consumption this will result in ..With UK prices at £1.50+ per litre I guess this is something I should really bottom out!

Does anyone have any figures (practical rather than theoretical, as there are so many factors at play)..?

Mal

[fredrosse]

I have a few steam plant tests conducted by Massachusetts Institute of Technology (MIT) in the early 1900’s. These tests were done with then state of the art equipment, and were in pursuit of advanced engineering degrees, not sanctioned by the manufacturers, so we get a look at how the steam plants of some early steam cars really performed.

A very condensed summary is as follows:

1904 Stanley Steam Car Tests, about 3 horsepower simple non-condensing engine. This engine used 400 psig steam, 27 pounds of steam per horsepower-hour, and required about 2.7 pounds of gasoline per horsepower-hour.

1908 White Steam Car Tests, 10 - 15 horsepower compound non-condensing engine. The White actually ran condensing, but no vacuum was attempted, so it is called “non-condensing”. This engine used 200 -500 psig steam, and required about 15 – 20 pounds of steam per horsepower-hour, with about 1.4 – 1.8 pounds of gasoline per horsepower-hour required.

1917 Stanley Steam Car Tests, about 13 horsepower simple non-condensing engine. This engine used 400 - 600 psig steam, 23 pounds of steam per horsepower-hour, and required about 1.65 pounds of kerosene per horsepower-hour.

The high inlet steam pressures here are far above what we typically use in steam launches, and these plants usually had high superheat.

As a guess for the Leak Compound in a well designed and well managed 27 foot launch steam plant, the following might be reasonably achieved:

Hull, 4 tons displacement, 6 knots, 6 SHP (shaft horsepower) @ 370 RPM, 24 x 24 prop.

Steam Plant, Compound Condensing, 150 PSI steam, 50F superheat, 20 in HgV
6 BHP @ 370 RPM, 18 pounds feedwater per HP – hour, and No 2 Fuel Oil (commonly called “Disell Fuel, we have to misspell it on this forum or the word gets modified) about 1.8 pounds per horsepower-hour required.

At the above conditions, with 6 HP output, we have about 10.8 pounds of fuel per hour.

Here in the USA we use “US Gallons”, equal to exactly 231 cubic inches, and a US Gallon of this fuel weighs about 7.06 pounds. Based on this, fuel consumption will be calculated to 5.8 liters per hour. Some simple math brings us, 4.5 Miles per US Gallon, or 5.4 Miles per Imperial Gallon. Note that slowing down a bit will significantly reduce power required, 80% speed requires only 50% power.

[fredrosse]

In the above metnioned tests, the dimensions of the 1907 model White Steam Engine were not given. Does anyone know the bore / stroke data for this engine?

[malcolmd]

Fredrosse, thankyou for a very comprehensive answer - these sounds like the kind of answers I was looking for... This would net out at £10/hr, painfull but not impossible - and as you say a little less rush would help a lot...

The figures quoted for the compund (3"+5"x3") are that it consumes 390lbs of steam an hour @120psi and 450rpm, and will produce 11.2IHP - but I think these feel like significant over estimates, and your 6SHP is much nearer the figures I get from my computation - However I was not sure about your 18lbs/hp/hr figure for feed-water. The steam cars were using more at significantly higher pressures.... would that not mean we would need to consume more steam at lower pressure/superheat? is this where the Leak-quoted figure of 34lbs/hp/hr (390/11.2) comes from? If this was correct then we would be talking about 11litres/hr (£18/hr ~$30/hr).

Well spotted that I was taking about the fuel named after the German inventor - why does the forum worry about that - it's not a brand name?

Malcolm

[malcolmd]

Fredrosse, thankyou for a very comprehensive answer - these sounds like the kind of answers I was looking for... This would net out at £10/hr, painfull but not impossible - and as you say a little less rush would help a lot...

The figures quoted for the compund (3"+5"x3") are that it consumes 390lbs of steam an hour @120psi and 450rpm, and will produce 11.2IHP - but I think these feel like significant over estimates, and your 6SHP is much nearer the figures I get from my computation - However I was not sure about your 18lbs/hp/hr figure for feed-water. The steam cars were using more at significantly higher pressures.... would that not mean we would need to consume more steam at lower pressure/superheat? is this where the Leak-quoted figure of 34lbs/hp/hr (390/11.2) comes from? If this was correct then we would be talking about 11litres/hr (£18/hr ~$30/hr).

Well spotted that I was taking about the fuel named after the German inventor - why does the forum worry about that - it's not a brand name?

Malcolm

[farmerden]

Malcolm- The "Steam Queen" 25ft burns 2.5 gal an hour at 6.3 knots [about half of that at 4 knots] The engine is 2 3/4 x 5 x4. Have you considered other oils ? I have yet to buy any oil. I've burned d-iesal with water in it [it was easy to separate the water out as water sinks ]I got three 45 gal drums of it free I've burned used car oil [I just run it thru a automobile oil filter to take out the lumps!][/img]

[fredrosse]

farmerden's boat comes up to 2.9 to 3.7 MPG, not too far from the numbers developed earlier.

My 20 foot sidewheeler gets about 4 MPG on Propane fuel, but the heat value of Propane is only about 66% of the heat value of No. 2 oil, (Die-sel). I think farmerden's numbers would be more representative.

A steam engine at maximum power and maximum RPM will often show much poorer economy (pounds of steam per horsepower-hour) than the same engine running with somewhat lower RPM and shorter cutoff, with good vacuum exhaust.

[steamboatjack]

Folks,
Not being very familiar with White engines, I was most interested in the pictures above, Is there a description to go with the item numbers? I may be mistaken but it appears to have a true simpling valve attached? This title is often misused in the UK for an impulse or starting valve.
Regards
Jack

[fredrosse]

From the 1907 Paper: “ The engine is a two cylinder vertical cross compound, fitted with plain slide valves moved by Stephenson link motion controlled by a hand lever at the side of the operator. It also has a simpling device (9), (10), and (11) fig. 7, controlled by a foot pedal, which is always used in starting, and in cases where a maximum of power is necessary for a short time.”

That is about all of the engine description in the paper. I know that later White steamers were also cross compound, but used piston valves and Joy's valve gear.

[87gn@tahoe]

I have a kerosene vaporizing burner heating my monotube boiler of 21sqft/hs, a condensing compound of 2"&4"x3.25" 6BHP@700rpm running 150psi and 450*F steam temp.

The boat is quite light (2200lbs) and slippery. I average 1 US gallon/hr at 8mph, confirmed with GPS.. As good fuel economy as my father's '77 Frod F250 with a camper shell and a 460ci V8.