Most efficient Steam Engine?

[Bernd]

Not to knock Alan's link to the Mike Brown's steam engine, but have any of you checked out the rest of his web site: "Mike Brown Solutions". It makes me a bit leary. He also advertised a few times in Live Steam. I don't know if anybody has ever tried his steam engines. My instinct tells me "Buyer Beware"

Here's the link to the main page: http://www.mikebrownsolutions.com/index.html

Make up your own mind after browsing the site.

Bernd

 

[mu38&Bg#]

The 20HP steam engine is exactly 20HP based on 200PSIG for ~50 percent of the stroke at 700RPM. Not being to familiar with steam, I can't say if the claim is realistic. If the valves and supply lines allow for 200PSI in the cylinder during that part of the stroke at 700RPM, then it should make rated power.

 

[Maryak]

Dp,

Your calc, (a SWAG by me), is probably the theoretical Indicated Horespower. It takes no account of steam losses in the cylinder or the frictional losses of the moving parts. Even if you are producing an actual IHP of 20 you will lose at least a further 12-15% driving the engine itself before you do any work on the load.

Hope this helps


Best Regards
Bob

 

[mu38&Bg#]

I understand there is loss between burning the fuel and turning the shaft. This is not different than an IC engine. The question I have is if you supply 200PSIG to the valves on this engine will it make 20 HP at 700RPM? The calc I did was BMEP, just like used in IC engines. To my surprised the figures were exactly 20HP, with no losses. So I wonder if the power spec is based on theory or if it was actually dynoed to rate it.

But, you're right. There is no way 100% of the 200PSI supplied can be converted to shaft power. I was thinking of it in terms of how it's used for IC engines. It is calculated based on the shaft power so all losses are already accounted for. So if the claim is based on input pressure and physical size of the engine, we can expect less than 20HP at the shaft. Any idea how much less?

 

[Maryak]

Dp,

Off the top of my head around 25%.

Unknowns such as quality of steam, quality of insulation, length-size-no.of bends of pipes between boiler and engine. The list goes on.

Best Regards
Bob

 

[shred]

I'd suggest that people/companies that did haul steam engines and boilers around the wilderness "back in the day", using wood for fuel, seemed to settle on the "donkey engine", which might say something still valid today about size, weight, and useful power output. I'd check into the various sizes those came in.

 

[Richard1]

Just random thoughts on your problem:-

1). Having driven this hand fired wood burning steamer

for a living in the past I don't think you can keep a sufficiently even firebox temperature hand firing wood to run a flash boiler. The less water you have in the boiler the more the fluctuations of hand firing will show up in the steam pressure. This isn't to say build a boiler with tons of water in it either but it is something to keep in mind.

2). The other point is the higher the pressure you have the smaller the engine can be for the same power which is why steam cars have been built to run on 1000PSI or more. Stanley were using 600PSI in 1911

3). Points 1 and 2 are probably incompatible.

Richard

 

[Maryak]

Richard.

Which paddler is that, can't quite read the name. ???

I have relieved aboard PS Marion out of Mannum South Aust.

The Shearer Steam car at the National Motor Museum in Birdwood SA operates at 350 psi using a coal fired Yarrow 3 drum water tube boiler. From memory the steam drum is about 10" OD and the whole thing is about 3ft tall. The two water drums are split in half to facilitate tube removal/replacement and the bottom 1/3 of the steam drum is a wrapper/tube plate. Quite a neat semi portable design.

Best Regards
Bob

 

[Richard1]

Bob,

PS Emmylou based in Moama works out of the port of Echuca, engine is a twin cylinder portable originally from a saw mill I think, 4.5 to 1 spur gear reduction to the paddleshafts if I remember correctly. I know of the PS Marion I think she was based at Echuca when I was working there, it was a long time ago. A year or two before that I had an interview for Chief (only) Engineer on the PS Melbourne which was a twin cylinder compound portable

Shearer steam car, I didn't know that one. I sent a scan of a B&W style water tube of similar size and pressure to a couple of people in this thread. This would seem to me to be a reasonable size for the job, reasonabley portable, have enough water capacity to smooth out the steam flow rate and of high enough pressure to make the engine of manageable size.


Best Regards

Richard

 

[Kermit]

Something currently being manufactured as a high pressure water tube boiler. Forced draft combustion etc. etc. I believe they indicated approx. 20-40 BHP for these models depending on pressure. About 5 feet tall.

They had a pdf of the boiler series I have attached for your inspection. not much info there though.

Kermit

View attachment Bryan_Pressure Vessels.pdf

 

[Greebe]

Lots of good info in this post.

I still like the idea of this concept. I know that it might be hard to get things to the proper weight and size though. How much HP do you guys think would be needed for such a project?

The other thing that I have thought about is a Stirling type engine, but from what I understand is that they are not capable of producing very much power. The Stirling would be a much better type of engine as you could just supply heat via you wood fire and cold via a supply of stream water in the summer and ice or snow in the winter.

Is there a Stirling engine that could be feasibly sized so as to work for these types of task that I am looking for?

Thanks
Greebe

 

[hammers-n-nails]

well i guess i was wrong about the weight. but as for how big of engine you need its really a matter of how fast you want it to do these things, a small motor will do just as heavy of work as a big one with proper gear reductions. its going to be hard to guess, you might just have to try something and see how it works for you. as for comparing gas to steam, horsepower is horsepower, the steam engine is going slow with alot of torque, the gas engine is going fast with less torque, with gear reduction its a wash.
i dont know much about stirling engines but from what i understand they are hard to build, hard to maintain, in efficient, and have a terrible power/ weight ratio.

 

[marttin]

I usually don't horn in before reading all the posts on threads, but I read the first question. But let me ask you this,

have you research a wood gassifier? That's on my 'to-do' list. It doesn't seem that complicated, but I'm still to build the prototype. There's a few sites I visited and it does seem like a good alternative to hauling gas.

Run a search, I have a few links I can dig out if you can't find it.