Author Topic: Wood Burning Stirling Engine (Read 18638 times)

JoeWXYZ · « **on:** October 18, 2009, 09:17:29 PM »

This is the first project that I am posting from my new home in B.C. It is a wood burning stirling engine.

It is made from stuff that I found around the place. It doesn't run yet, maybe next month.

This next picture was taken in the winter last year of the water pipe we installed in the creek here.

Another view:

Here in this place the deer run free and codey our dog guards the cabin

Enjoy,Joseph.

GeeMac · « **Reply #1 on:** October 19, 2009, 06:13:00 AM »

Great pics. I was just out in Victoria from Albera. In what part of BC are you?

BigBreaker · « **Reply #2 on:** October 19, 2009, 07:13:23 AM »

I am curious what working gas you intend for the stirling engine and what pressure? Air, He, H?

Are you building a regenerator into the passage between the hot and cold sides?

JoeWXYZ · « **Reply #3 on:** October 19, 2009, 07:34:27 AM »

GeeMac, We live in northern B.C. near Francois Lake.

Joseph.

JoeWXYZ · « **Reply #4 on:** October 19, 2009, 08:06:01 AM »

BigBreaker, I am using air as a working fluid, maybe He later. After I fire it up the pressure runs about 10 psi, haven't measured the vacuum yet but it sucks. The regeneration is incorporated into the displacer piston. The challenge in the operation is the heat transfer through the air on the cold side. This is what I am working on now.

Joseph

bj · « **Reply #5 on:** October 19, 2009, 08:18:12 AM »

Great Joseph--as always, interesting. Give cody a pat on the head from me.

bj

ghurd · « **Reply #6 on:** October 19, 2009, 09:09:48 AM »

I want to know more about the water wheel plan!

G-

cr8zy1van · « **Reply #7 on:** October 19, 2009, 10:01:52 AM »

Joseph,

Do you have plans for large sterling engines or are you building this one by trial and error? I am very interested in building my own but lack any knowlege about them. The information I have been able to find online is mostly about toys with no practical application. The only link to larger engine was this: link but the author seems to have gone offline and hasn't responded to any emails.

a.

JoeWXYZ · « **Reply #8 on:** October 19, 2009, 11:19:48 AM »

Cr8zy1van, Yes I am building a workable unit out of readily available stuff. An old truck rim for the fire box, expired 100lb propane bottles etc. My most favorite is the exercise bicycles and machines. You can find them anywhere and free. Good flywheels and metal.

Joseph.

JoeWXYZ · « **Reply #9 on:** October 19, 2009, 11:35:29 AM »

ghurd, The wheel is made from a heavy bicycle wheel and triangular aluminum plates, curved and each one held in place by two screws into the rim. I calculated the spacing so they would line up exactly. Our creek is has heavy run off and the head is over 500 feet. At this point we only have 50 feet of pipe on it to get the height of six feet. The cracks formed in the aluminum because the plates had holes along the sides. I will strengthen the new plates with heaver material. The wheel runs slow 4 rps but it is 24-7. We plan to bury the pipe next year and build a power house to protect the next wheel.

Joseph

Stonebrain · « **Reply #10 on:** October 19, 2009, 12:57:55 PM »

Hi Joe,

good to see you back again.

Your stirling engine looks great,like most of your creations.

it looks big for a stirling,if it's your first,but who knows...it will work?

I sure will follow your weekly projects.

cheers,

stonebrain

ghurd · « **Reply #11 on:** October 19, 2009, 04:14:07 PM »

Wow. 500' of head with that flow, and burying the pipe would have been one of my priorities.

Turn that wheel a few degrees and it looks like the half-a-Pelton type (that I can not recall the name of).

I thought the AL version was replaced by a generic white plastic version, which was in the pic.

How many predictable watts in that water?

Anyway, good to have you back.

G-

richhagen · « **Reply #12 on:** October 19, 2009, 10:39:36 PM »

It is good to see your interesting projects again after a break. It sounds like you have some good hydro potential. Rich

BigBreaker · « **Reply #13 on:** October 20, 2009, 07:08:12 AM »

Yes - for Stirling engines the blessing is also the curse. You can run any fuel you want, as dirty as you want, because it operates with external combustion. But you need very efficient heat exchangers on the hot and cold side for the heat to flow through the device properly.

If you ever want to actually use your engine for meaningful power, you will need to run the working gas at high pressure. That means you need a good high pressure heat exchanger for both ends. On the hot side, that becomes a materials constraint and puts a ceiling on your operating temperature and therefore efficiency. Standard pressure or +10psi is not going to cut it. The volumetric heat density of the working gas is just not high enough until you get up to hundreds of psi.

See what it takes to build a 400psi heat exchanger running at 600C+. The heat weakens most metals. Aluminum is obviously out and that's too bad because it has excellent thermal properties. It could work on the cold side assuming mixing metals doesn't cause galvanic corrosion. Steel isn't great for thermal conductivity but it can take the heat and the pressure. That's the route that most commercial engines went. With steel you see a lot of "flower" shaped steeling tubing configurations. Basically you want to keep the steel thin and let the combustion gases flow through lots of sthin steel surface area. I'm sure there are other designs that work but that's what I saw in my survey.

JoeWXYZ · « **Reply #14 on:** October 20, 2009, 09:15:11 AM »

BigBreaker, You are correct in your understanding of efficiency. This unit just has to run for the project to get wings. I will put it in the local fair here to get some interest in the project. Building it is the fun part. If it doesn't work to good I will call it ART.

Joseph.

bob golding · « **Reply #15 on:** October 20, 2009, 03:48:01 PM »

hi joe,

i have a solar powered rankine cycle engine design i want to build when i get some of the other more important projects out of the way. it uses propane as the working fluid. a friend of mine who first thought of the idea did make something that proved the theory worked but moved on to other projects,and dismantled the prototype. the nice thing about propane is you can get a large pressure difference over a small temperature range. it uses the propane indirectly to move water, so the propane never leaves the pressure vessel. i will dig out some more info if you are interested. its all pretty basic and uses simple parts. the only part that might prove difficult to make is the diaphragm, but you can buy an off the shelf one.

cheers

bob golding

fabricator · « **Reply #16 on:** October 20, 2009, 06:02:36 PM »

I've got a lot of art piled around here.

wooferhound · « **Reply #17 on:** October 20, 2009, 06:12:18 PM »

It already looks like a Teapot !?

scottsAI · « **Reply #18 on:** October 20, 2009, 07:29:48 PM »

Hello a.

Stirling engine requires high Internal gas pressure to get any power out of the engine.

Using open design it takes a huge engine to generate 1 hp, of limited value.

To check out your designs use Stirling simulator:

http://www.bekkoame.ne.jp/~khirata/academic/simple/simplee.htm

Key to efficient Stirling engine is the Regenerator. Discovered why most Stirling engines do not live up to their expectations: http://www.ent.ohiou.edu/~urieli/stirling/simple/regen_simple.html

Few percent loss in regenerator = 10's of percent loss in engine efficiency.

I refocused on a steam engine. Some day may even build it. Laid off...

I am interested in Stirling engine discussions, email's or forums works.

Have fun,

Scott.

willib · « **Reply #19 on:** October 20, 2009, 08:39:13 PM »

Man, You are SET for power.

240 RPM is a nice speed , and with a bit of tweaking on a nozzle of some sort ,who knows?

You will need some more pipe to boost the pressure a bit . But hey, everything is in place for JBCPC ,

Joe's BC Power CO.

If I had that flowing near me ...

I see the problem though ,The top of the hill is really,really far away if 50'->6'

100'->12' ect. slippery SLOPE huh? or not enough .

How much pipe does joe need to get 1 HP , 24/7 ?

Those calcs are beyond me?

anyway Have fun,and its nice to see ya back..

Bill

JoeWXYZ · « **Reply #20 on:** October 20, 2009, 09:05:54 PM »

Woof,LoL, My wife named it the tea pot.

Joseph

JoeWXYZ · « **Reply #21 on:** October 20, 2009, 09:13:13 PM »

ScottsAI, Thanks for the link. The simulator tells me i am going to get 11240 watts--? I must of fed in some funny data. Math ain't my strong suit.

Joseph.

JoeWXYZ · « **Reply #22 on:** October 20, 2009, 09:18:09 PM »

Sounds like it is up my alley bob, thanks for the interest.

Joseph

scottsAI · « **Reply #23 on:** October 20, 2009, 11:22:22 PM »

Joseph, no way 11kw with 10psi pressure. More like in 10's watts.

Check your units / conversions, I slip digits...

Simulated couple designs of production Stirling engines very close to actual engine claims.

Noticed many Stirling engine bookmarks no longer work.

Have fun,

Scott.

spinningmagnets · « **Reply #24 on:** October 21, 2009, 06:01:41 AM »

Bob, You can find more info and links to others projects to compare notes on possible variations to a propane Rankine cycle by using the search term Organic Rankine Cycle (ORC) and I have read about using toluene, Butane, and various types of Freon (along with propane) There are some clever ideas over at Lee's "packrat workshop" http://www.packratworkshop.com/alteng.htm

I am not in a position to build a prototype (also I don't need one) but a "freon-steam engine" (ORC) is very viable. For heat, a solar concentrator doesn't have to be big, and the condenser can be air fan-cooled.

If you are buying a system from a store and having a mechanic install it, a solar-PV panel is cheaper and easier, and lower maintenance. But for me, I can't make a solar-PV panel, however I CAN build a solar ORC with my labor and half-free junk.

Stirlings, the Rider-Ericsson one-cylinder Beta is probably the best power producer per size and weight, but it will still be large compared to the power it produces.

Its complex in order to keep internal gas volume low. Requires a large diameter machined piston and cylinder. Power piston will have two connecting rods to free up center, and displacer rod passes from crank through piston in a straight line, so you must actuate displacer with a Scotch yoke.

The original Rider Alpha-Stirling (1886) is probably the best power producer a garage builder can copy. The two vertical parallel cylinders do not need to be machined in their bores, the two pistons are simply pipe sections that need a very smooth OD surface to seal around leather seals located at the crankshaft end (top) of the cylinders.

Machine came with a small adjustable-stroke air-pump to add a little air at the point of lowest internal pressure, with an adjustable relief valve to maintain 2-atmospheres. It leaked a little hot-air past the leather piston-neck seals, but the leather rings were easy to make and replace.

One cylinder has a water-jacket, and the other has a fire-box around the lower half.

http://2.bp.blogspot.com/_WyIc2oXjvmc/SqkwRIy2OHI/AAAAAAAABYY/_R2Fe53jpf0/s400/Stirling+rider+engine
.jpg

Here is an index with a transcription of the patents (patent photos on the web hard to read). It will be big and heavy to produce one-HP (as Scottsai has said). I have never built one, but they sold over 30,000 before WW-one, so they work.

http://tech.groups.yahoo.com/group/HotAirEngineSociety/files/Ron%20Roberts%20stuff/

In the same index is a list of significant stirlings (over 40 names) so you can look up what companies with research budgets thought worked best.

JoeWXYZ · « **Reply #25 on:** October 21, 2009, 08:30:20 AM »

Spinningmagnets, Thanks for the links. Lee's site is cool. I will have to look it over when I have a free time.

Joseph.

HaroldCR · « **Reply #26 on:** October 21, 2009, 10:06:35 AM »

My Dad had a Rider-Erickson. It had a water pump on it, and, it was not a big pump. I'm thinking it was about 4" long X 3/4" bore. It was for pushing water up to a barrel, for gravity feed.

I'm also thinking it was a 4 X 3. 3" bore X 4" stroke. Flywheel was about 16" diameter, and 1½" thick, spoke type. 1 man could not easily load it into a pickup truck. He made a cradle and laid it down, then shoved the whole cradle onto a low built trailer he had. He put a Gas water heater burner under the engine and ran it on Propane. Had very little power.

He also had flame-lickers, that ran by sucking a flame into a slide activated reed port,on the side of the cylinder, then "popping" as it fired and turned the crank. Still no power.

bob golding · « **Reply #27 on:** October 21, 2009, 05:15:56 PM »

thanks for links,

it was lee i was thinking about with his design. i am still waiting for powerchips to start production of there peltier chips. they seem to be a bit nearer production. been waiting about 5 years, must be just around the corner. i thought that about the vanadium batteries as well. low tech definitely seems the way to go. the current project is passive solar heating. i can build that and, hopefully the use the waste heat i dont need in the summer to drive a orc engine. not sure about the cold side though no water here and it gets hot in the summer.

bob

Ungrounded Lightning Rod · « **Reply #28 on:** October 22, 2009, 06:04:59 PM »

Half-a-Pelton? You mean a Turgo?

About 150 meters head and decent flow. This turbine application chart says you're in the sweet spot for a Turgo, and a decent spot for a Pelton.

A Crossflow (Banki-Mitchell / Ossberger) might need more flow than you've got to be a commercial success - but they're SO easy to build that a small one might still work out for your application. (They're just a (couple) squirrel cage(s) on the end of a generator's shaft, in a housing with some water guides and water seals on the shaft bearings. And you can always protect the genny from spray from a leaky seal by putting a "slinger" disk on the shaft between the turbine housing and the genny.)

With any of 'em you should be able to design a runner so your RPM is right for using a handy induction motor as a generator and it looks like you've got enough flow to pay the excitation costs so you wouldn't need a magneto conversion. (If I've run the numbers correctly your jet emerges at about 8.77 meters/second less friction, so you want the jet to hit a turgo or pelton about 5 3/4" out from the center of the shaft to get 3600+ RPM for a two-pole, twice that to get 1800+ RPM for a four-pole.)

Ungrounded Lightning Rod · « **Reply #29 on:** October 22, 2009, 06:05:49 PM »

Typo: Make that about 8.77 meters/second less friction,

Ungrounded Lightning Rod · « **Reply #30 on:** October 22, 2009, 06:07:05 PM »

ARGH! 8.72 !

spinningmagnets · « **Reply #31 on:** October 23, 2009, 06:17:12 AM »

Joseph, its good to see you back on-line. Your posts were very inspirational. I go the impression that before you worked at a machine shop that allowed you to work on personal projects on lunch-break?

Glad you achieved personal goal of backwoods property, but does that mean you have no access to a shop?

I was and am still enthusiastic about Stirling engines, but after re-reading this thread, I want to emphasize if somebody makes one and gets it to work, it will be very big and heavy, and the power will be small (like a VAWT?) and I only anticipate being able to charge AA, C, and D batteries for LED lights and music.

A simple one-atmosphere engine should have a "suck-in" relief valve, because after heating the air (pressure) and some minor leakage, the cold part of the cycle will eventually draw a partial vaccum, and slow to a halt.

It is important for efficiency to have a small internal gas volume, so, heat exchange is vital. Cold-side works well with water jacket. The original Rider was used to pump water from a well up to elevated water-replentishment towers on the steam-train lines (in places that had inadequate wind to use the preferred wind-pumper). The water-flow cooled the cold side cylinder as it was being pumped.

The other popular application was hotel water cistern pumping and heating. A low-wage boy would start a fire in the Rider, and it would pump and heat water to the elevated tank, which then overflowed into the cold-water supply tank.

This provided warm and cold gravity-feed water to the hotel rooms. When the fire went out, the Rider stopped pumping. Just before WW-one, they were widely replaced with better performing electric motors, and were melted for scrap.

If you don't have a total-loss water supply (like a solar Stirling in the desert) you might consider having the water-jacket flow through an elevated loop with a vented expansion tank at the top. If the two columns of water are equal height, and the down-flow leg is made of cooling radiators, there will be a thermosiphon effect, and any water pump thats needed can be very small.

If a small water pump is needed, it would not be hard to make a seal-less magnetic impellor to eliminate the shaft with its leakage and friction.

If you do everything "just right" you will end up with a large heavy machine that consumes a lot of fuel and makes a tiny amount of power.

JoeWXYZ · « **Reply #32 on:** October 23, 2009, 07:43:05 AM »

spinningmagnets, one of the reasons why the move was so hard for me because we brought all of the shop equipment with us. We are building a shop now to put the stuff back into. Here we don't need any permits to build, that's one of the major reasons we moved, nobody to bud in to what we are up to.

Stirling engines are just the conversation piece. They are quiet and can be installed inside of the house, mostly for the heat. Because the climate here is so cool most of the time it is a very good alternative. A do nothing machine that looks good. My job in this life is to create lots of do nothing stuff and have fun doing it.

Joseph.

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Author Topic: Wood Burning Stirling Engine (Read 18638 times)