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# Thread: 10 hp steam engine plans?

1. MusicMan

I looked at hobbysteam.com and was pretty thorough in my search and did not find and large steam engine plans. It seems to be mostly hobby stuff. In regards to burning wood to fire the engine, I am looking a a large 10 foot parabolic satellite dish and covring it in mylar so that it concentrates all the suns energy onto a small area about 8" x 8" and the concentrated heat is about 800 degrees I believe. In this area they run pipe to carry the hot water and steam to the engine. I have a link to it somewhere and will post it next time.

2. Originally Posted by txcowdog
MusicMan

I looked at hobbysteam.com and was pretty thorough in my search and did not find and large steam engine plans. It seems to be mostly hobby stuff. In regards to burning wood to fire the engine, I am looking a a large 10 foot parabolic satellite dish and covring it in mylar so that it concentrates all the suns energy onto a small area about 8" x 8" and the concentrated heat is about 800 degrees I believe. In this area they run pipe to carry the hot water and steam to the engine. I have a link to it somewhere and will post it next time.

sort of flash steam system? sunlight might have 350 btu/hour hitting the earth. at 10', 35 of those dishes would get you 16 hp to use the same wood fired boiler metric, assuming perfect reflection, all other efficiencies being equal. there is a lot of waste in the conversion to steam then mechanical then electrical - why not photovoltaic or some such thing? i know they are expensive, but so are 35 10' dia parabolic dishes. 800 degrees is not to be trifled with, then again flash is less dangerous than a boiler i believe. maybe it could run a turbine instead of a steam engine.

if its running a fridge, you don't need 10+ hp. start small and simple, figure out the math an engineering, understand the safety concerns of pressurized steam vessels and see what you come up with. the quantification to assess the idea was like 2 minutes of googling so don't take it as gospel or proper engineering, time for the builders to do their homework and hopefully convert this from idea to reality.

3. Don't worry about trying to make a steam engine; they are woefully inefficient and it is very difficult to vary the power output in response to varying electrical demand.

Have a look at this approach:

http://www.green-trust.org/woodgas.htm

4. Use batteries and an inverter if you go with a steam engine. And a steam engine might just be the way to go.

A little math to look at is the average home consumes about 12 million watt/hours per year. Now a cord of wood on average has 25 million BTUs. A boiler is about 80% efficient and the steam engine is about 10% efficient if you go with a compound or a very short cutoff simple. Now there are 2544 BTUs in a HP/hour and 746 watts in a HP. The generator will run 80% efficient and lets go 80% on the charging and 80% on the inverter also. With all that you get this:

25,000,000 BTU x 80% = 20,000,000 BTU

20,000,000 BTU X 10% = 2,000,000 BTU

2,000,000 BTU / 2544 BTU = 786 HP

786 HP X 746 = 586,356 W

586,356 X 80% = 469,000

469,000 X 80% = 375,200

375,200 X 80% = 300,160

12,000,000 / 300,000 = 40 Cords of wood a year.

Now lets figure out how big of a power plant you need.

12,000,000 / 365 = 32,877 W per day

32,877 / 24 = 1370 W per hour

1370 / .8 = 1712.5 (inverter)

1712.5 / .8 = 2140.6 (batteries)

2140.6 / .8 = 2676 W (generator)

2676 / 746 = 3.6 Horse Power Steam engine.

Personally I think one could get by with a lot smaller engine by using the steam to heat your home and water and possibly cooking. Using a solar panel in the mix is also a good idea too.

There is my two cents now here is a link to some engines including a 5 H.P. compound and they have a 10 H.P. wood burning boiler going by the name of Roberts too. They don't advertise it but they will construct the Roberts boiler for about \$10,000.

http://www.pioneer.net/~carlich/RSE/RSEengines.html

5. ## solar cells

Hi, here are the best (that I know of) solar cells for your appl. Probably not cheap.

http://www.spectrolab.com/prd/terres/cell-main.htm#

6. Steam engine efficiency
It is a long time ago now but when I did my apprentice training I was taught that a steam turbine was over 70% efficient and a diesel was 12%. A steam piston would probably less efficient than a turbine but would still be miles ahead than an ICE, stirling engines I don't know.

Steam engine efficiency
It is a long time ago now but when I did my apprentice training I was taught that a steam turbine was over 70% efficient and a diesel was 12%. A steam piston would probably less efficient than a turbine but would still be miles ahead than an ICE, stirling engines I don't know.
I think you should do a little bit of looking around. Diesels are around 30% efficient. If they are turbocharged or compound cycle running at a constant or near constant speed this can be pushed up to around 45%, maybe. Multi-stage steam turbines can approach 40% efficiency, stationary gas turbines can approach 45% efficiency. Modern gasoline engines are around 20% but this varies because the efficiency falls off badly at low speeds; running at constant speed on a constant load they will get 20%. Steam piston engines are pitiful at 5 to 15%; compound expansion steam piston engines will get better than that but will not match a gasoline engine let alone a diesel.

Whoever gave you the 70% for steam turbines and 12% for diesel was totally out to lunch. Just think about it for a while: Diesel supplanted steam for railway locomotives and ships decades ago. I think the last steam turbine powered vessel, excluding nuclear powered naval vessels, was the Queen Elizabeth 2 built in the late 1960s with steam turbines and refitted about 20 years later with diesels. All modern freight ships are diesels and modern passenger ships are all diesels or a combination of gas turbine or diesels. These changes would not have taken place if steam turbines were more efficient than diesel or gas turbines.

8. ## Engine efficiency

Hi, I have been studying the engine efficiency area quite a bit lately, as well as the thermodynamics aspect.

One of the key aspects of comparing engines is not just the type of engine, but its MEP (mean effective pressure). From a practical aspect, you want the most turbo / super charged engine you can get in order to achieve high efficiency. A non-turbo charged engine of any kind will be very inefficent.

You also want one that gives plenty of burn time to the fuel (long stroke).

From a "best you can buy" perspective, stirlings are near / at the top.

Highly turbo charged diesels are a close second, with 45 plus %

Gas turbines (high end) are around 35 - 40 % ( I was surprised)

Typical auto gas engines at optimum rpm run about 20 %.

A low end, non turbo charged, low speed diesel is approx 10 - 15 % Quite a drop without the turbo.

Seriously consider using an old MB turbo diesel engine attached to a generator, and use the waste heat for your heating needs.

9. Originally Posted by harryn
.....Seriously consider using an old MB turbo diesel engine attached to a generator, and use the waste heat for your heating needs.
And if you want air conditioning look into using the waste heat to run an absorption type heat pump.

And if you insist on using wood as a fuel make a pyrolyser to generate gas to run your engine; actually you supplement the diesel with the gas, the diesel still provides the ignition.

And use the charcoal from the pyrolyser in your barbeque.

10. Regardless of method (steam or gasifier), it is going to take a lot of wood to run a multi horsepower generator. From a handling standpoint, moving that much wood will require grinding it into chips, which is not a bad idea in general.

If you stay with the steam engine idea, perhaps an easier approach would be to start with an existing car / truck engine, and just convert it to run on steam. If you are running at perhaps 3 atm, it might be feasible. Use the "exhaust" for heating your house.

Steam is really hazardous stuff - more so than people realize. I am not trying to talk you out of this path, but there is a reason that the ASTM and similar pressure vessel standards came into being - to reduce the number of steam pressure vessels that exploded each year. This is not the place to economize.

If you have a 4 cylinder engine, convert it to run on 2 cycle instead of 4 cycle, then in theory, it could run on steam.

In that climate, perhaps a windmill might be a candidate for at least 50 % of your electrical needs. Solar photovoltaic is cool, but I am not so sure it is cost effective (being kind) that far north.

The really efficient wood chip burning systems (commercial) use moving grate designs.

Another, somewhat crazy, but possibly useful alternative to buring the wood, would be to sell the carbon credits. In theory at least, if you cut down the diseased trees, package them in a way that the rotting process cannot occur / no CO2 is released, then re-plant new trees, you are sequestering carbon.

There is a whole industry being built around selling these carbon credits for real cash. I know the US EPA has a link to this setup, and the EU guys are excited as well with the idea.

You might be able to use the cash from the credits to buy a fuel which is easier to manage / use in a remote home than a complicated wood to gas / steam to power setup. Even with that, a small co-gen setup (diesel engine for electricity / heat) might be useful.

The water turbine approach suggested is good, as long as the water actually is flowing, which is not exactly year around everywhere.

Steam engine efficiency
It is a long time ago now but when I did my apprentice training I was taught that a steam turbine was over 70% efficient and a diesel was 12%. A steam piston would probably less efficient than a turbine but would still be miles ahead than an ICE, stirling engines I don't know.
Good comparison !

12. ## out to lunch

So all those RAN marine engineers were out to lunch?
I stand corrected I looked around and it seems that diesels are more efficient than I remember. As for steam turbines check out http://www.engineersedge.com/thermod...components.htm they seem to think that small turbines are 60 to 80% efficient and large ones 90%, they must be out to lunch.
PS if you are refering to nuclear powered steam you may well be right because nukes use low grade saturated steam unlike conventional systems that use superheated steam.
As for merchant shipping switching to diesel that is more about the startup shutdown times. Warships use either steam or gas turbines, some use the gas turbines for a quick start and then switch over to steam. Trains were changed for the same reasons also pollution was a factor.
In the US GM and the oil companies put the squeeze on politicians for obvious reasons. Many changes in engineering have more to do with politics than common sense.
AJ

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1. ###### 5 HP Steam Engine Plans
03-20-2013, 05:04 PM