Stirling Engine

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LindaBobzien's picture
LindaBobzien
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Stirling Engine

Here is an interesting thing I came across thru work today.  It's very old technology called a Stirling Engine.  I wonder if it could be useful?  Rigged up so to speak? 

http://money.cnn.com/2009/03/23/smallbusiness/solar_power_infinia.fsb/in...

http://en.wikipedia.org/wiki/Stirling_engine

 

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Re: Stirling Engine

 Very cool. Thanks for posting.

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Segway and an electric Car use a Stirling Engine

The Segway uses one:

http://www.stirlingengine.com/FullPower.adp

The same inventor used it for a car too.

http://hackaday.com/2008/11/09/dean-kamens-stirling-engine-car/

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Re: Stirling Engine

The Stirling engine is a heat engine just like the internal combustion engine or steam locomotive.  It relies on a source of heat and a reservoir to absorb that heat.  In the process of the heat transfer, it can do useful work.  The Stirling cycle is very efficient compared to the other two.  It also has fewer fuel limitations.  That said, it is no panacea.

On a small scale (household, small business) a Stirling cycle requires a cheap abundant fuel to provide reliable power for useful work.  On this planet, that means some form of carbon compound suitable for combustion.  Currently, the best bang for the buck is still fossil hydrocarbons.  Sad, but true.  Everything else has lower returns in terms of energy per unit mass and recovery from the environment.  If your time is worth anything, buy petroleum to run your Stirling engine.

Solar produces heat if sufficiently concentrated.  The higher the concentration  the greater the efficiency.  Focusing sunlight on a Stirling engine can produce very high temperatures.  The trick is to compensate for the Sun's motion and the problem of it disappearing over the horizon each day.  Passing a working fluid through a stationary collector may be easier to manage, but it still means quite an investment in infrastructure to collect the heat.  If your working fluid can undergo a convenient phase change, storing heat for use after dark can be more efficient, but likely more expensive.

Getting heat off the electrical grid is a non-starter.  Better to just buy an electric motor.  Same with wind.  With wind you do have the option of using the mechanical energy directly.

One of the challenges with alternatives is how to renew the technology after the oil and coal runs out.  There's a lot of talk about running this and that on renewable energy, but how about producing this and that without the fossil carbon based infrastructure?  Every mechanical system eventually wears out and must be repaired or replaced.  This means melting metal, casting it, rolling it, forging it, welding it, machining it, etc.  Not much of this is happening with alternative fuels.  The Stirling engine is a clever idea, but without the current support systems, it may be of less utility than a water wheel.  It reminds me of an old saying that a gun without bullets is just a club.

To be blunt about it, a Stirling engine in your car is not a transition to a low energy, localized economy.  It's an attempt to hang onto delusions about happy motoring into the distant future.  The problem is not that we have the wrong kind of cars, but that we have a life centered on cars and all of the infrastructure that supports and demands it.  As we descend Hubbert's Curve, personal transportation and all that it entails will be too energetically expensive.  The sooner we jettison it, the sooner we can begin to bring our infrastructure in line with what we can realistically expect from the future.  The longer we wish upon a star for Stirling engined automobiles, the more difficult the inevitable transition will be.

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Re: Stirling Engine

I'm with Durangokid I'm afraid.....  it just goes to show with fossil fuels you can do anything, even make/run sterling engines off alternative power.

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Re: Stirling Engine

I currently work in aerospace, and believe it or not, applications and further development of the Stirling Engine is an interest, only this time to power aircraft. Currently the power output is lower than combustion, but it does work rather well. The design I have seen tossed around work uses sets of pistons and cams to create rotary motion. It uses hot and cold air to cycle the pistons, and a heat exchanger to recycle some of the heat. Thats about all I know about it.

Here is the thing. The military probably already has in development alternative sources of energy not reliant on fossil fuel. They are just secret, partly due to corporations financial interest, and/or fear of the technology being duplicated by hostile countries. Someday maybe they will declassify it. Most major technological advancements were born in military and filtered out to civilian society. GPS, internet, nuclear fusion, ect.....

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Re: Stirling Engine

Has anyone seen the car that runs on compressed air? This could be the ticket, if they can get the car to compress its own air. Cool beans.

http://www.popularmechanics.com/automotive/new_cars/4217016.html

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Re: Stirling Engine

However Stirling's are relatively easy to make, even with low tech tools (Couple of Con-Rods, Fly-wheel, two pistons and cylinders, a length of Copper tube that can hold pressure, some bolts, and maybe some compression fittings).

The hard thing to make would be the pistons, and cylinders, but that could be salvaged from an internal combustion engine. Which while it "used" fossil fuels in it's original construction, you're not using much more in it's salvage/repurposing. Chuck one cylinder or engine end in a fire (not literally of course) and Robert is your fathers brother (or less cryptically it works, maybe, once everything is up to temperature). Better yet if you can run this off waste "heat" then you are converting that heat into some form of usable energy rather than losing it to the environment.

Another relatively cool technology that has a relatively simple construction (at least in comparison to mainstream) is the Tesla Turbine (I investigated this for possible steam powered electricity generation). It consists of a series of plates, and works on friction. Anyway I digress.

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Re: Stirling Engine
SPM wrote:

Here is the thing. The military probably already has in development alternative sources of energy not reliant on fossil fuel. They are just secret, partly due to corporations financial interest, and/or fear of the technology being duplicated by hostile countries. Someday maybe they will declassify it. Most major technological advancements were born in military and filtered out to civilian society. GPS, internet, nuclear fusion, ect.....

SPM -

Wrong verb tense.  "Developed" is correct. 

FM:  USS NAUTILUS

TO:  COMSUBLANT

DTG:  17JAN55 1600Z

SUBJ:  DEPARTURE REPORT

1.  UNDERWAY ON NUCLEAR POWER.

BT

 

One more minor point of order - nuclear fission not fusion - as far as an energy source.  Although a fusion weapon does release a lot of energy.  Just a tad bit tricky controlling it once primary ignition has started. 

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Re: Stirling Engine
Gungnir wrote:

The hard thing to make would be the pistons, and cylinders, but that could be salvaged from an internal combustion engine. Which while it "used" fossil fuels in it's original construction, you're not using much more in it's salvage/repurposing. 

The piston design is the toughest,  I have read that is recommended is made of a very wear resistant and light material like carbon due to you do not want to use lubricants  Lubricants have a tendancy with heat and the fluids that are used in the system like air could start a fire.  Oh the recommended fluids for these systems are air, helium and Hydrogen gasses.

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Re: Stirling Engine

I'm restrained by what I can't say.

I will use the Stealth Bomber as a reference. It was developed during the 60s, and finally went public in late 80s. Only because people were sitting with cameras outside the airports in the morning waiting to catch a picture of it taking off. Almost 30 years of being classified.

All I am saying is the powerplant they tell you it has, it might be different. The military test all kinds of alternative power sources since it would directly benefit them. Besides they have free access to the patent library. As soon as they see something that may benefit them they swoop up the technology, usually with original creator, and fund further development, everything becomes classified depending on level of national security ascribed to it. Since funding for military projects is significantly higher than university labs people usually gravitate towards the military side. The military does fund university projects as well.

The government loves UFOs because it gives them an coverup to hide black aircraft testflights. Anyone remember the reports of all kinds of UFO sightings in Nevada of a triangle aircraft, with lights on each corner? Sneeze.. F-117. They have gotten smarter now.

Not to argue on the fusion fission, but the government intent was fusion and the civilian sector currently uses fission. Similar with Radar and the microwave. You are right though becasue I meant to say fission.

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Re: Stirling Engine

The materials you need exist. This isn't my design, so I don't want to give too much of it away. The guy had a setup where it was a tube structure with a set of pistons like pancakes inside the tube. I don't recall how many pistons he had in there, but the hot air would enter alternating between every piston, causing the pistons with hot air in between them to push apart, and the cold air to push together. He would turn the linear motion of the pistons into rotary through a cam follower setup. It was a pretty cool design.

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Re: Stirling Engine

Ahhh....The blackbird was a UFO for many years too...The public swore on that.

But I find the Stirling Engine fascinating. Imagine if one could be developed that fit through a wall of your house and was reversible. The cold side would go outside in the winter and would be reversed to the inside in the summer.

Here is one that runs on nothing but sunshine:

http://www.motherearthnews.com/Renewable-Energy/1978-05-01/MOTHER-Runs-a...

Ironically, I remember my 9th grade science teacher having one of these on his desk near a window and everytime I walked in there, that little engine was running smoothly.

Also, I found the air powered car fascinating as well. Had never heard of that!

 

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Re: Stirling Engine

Hey, I read that they have used the Stirlings in submarines. I thought that was kind of interesting.

I would really like to give a wood gassifier a go.

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Re: Stirling Engine
jerrydon10 wrote:

Ahhh....The blackbird was a UFO for many years too...The public swore on that.

Nothing to do with the thread subject but since when has that stopped anyone? 

 

http://www.greatdanepromilitary.com/SR-71/index.htm

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Re: Stirling Engine

SPM and others interested in wood gasification:

I purchased a wood gasifier experimentor's kit (G.E.K.) from All Power Labs in California recently. It arrived just the other day in a 40 gallon drum. The drum looked like it had been dropped from an airplane at low altitude when it arrived, but the innards seemed undamaged. I ordered a kit complete with all parts, but no welding done. This saved about $1,000 over the cost of the pre-welded and painted G.E.K. A friend of mine is welding it up. My welding skills are minimal.

My understanding is that the G.E.K. will power a 7.5 KW gas generator, which is enough juice to handle most household needs. There are a few limiting factors. One is the requirement of a steady supply of wood. That's pretty obvious. What is less obvious is that the moisture content in the wood must be very low or it will gum up the gasifier. For the initial firing we will probably purchase a bag of wood pellets normally used in a pellet stove.

It is my intention -- once we have the thing assembled and running -- to start a new thread with information about what we learned from the experience. I expect that at least some others may be interested. If the mistakes we will inevitably make along the way help keep others from repeating those mistakes, it will be worthwhile.

Excuse this post on a Stirling Engine thread, but SPMs post motivated me to mention this.

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Re: Stirling Engine

I would appreciate tremendously if you could post that information. I have read a little on the topic but good efficient plans are dificult to find. All I could find was plans of older downdraft models. I wish GEK's pictures were bigger on the website. Did you get the Level III kit? That looks like a nice setup. I bow in admiration.

Doesn't it turn the wood into usable charcoal?

I tried bringing it up in a few other threads, no one bit on it.

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Re: Stirling Engine

Is the output from the gassifier used to run an internal combustion engine hooked to a generator?

I did find bigger pictures in their gallery section. I wish I had a CNC Plasma Cutter.

I have some of the stuff for controls like thermocouples ( I only have one J ), temp controller, PLC's, switches, relays. If I got the steel parts only, what else would you need or be involved? I'm thinking maybe purchase the tank kit, Fan kit and cyclone kit. Do you think a lot of stuff would still need to be purchased?

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Re: Stirling Engine

Sorry I did not make this clear: The G.E.K. produces wood gas that will power an internal combustion engine (spark ignition type, not compression ignition). The Level III G.E.K. kit that I purchased is said to be of sufficient size to power a 7.5 KW generator set.

All Power Labs recently sent me an e-mail with some video clips attached. The video clips show the G.E.K. in actual operation and there are some comments by users who have built and operated the kits. That's how I learned, for example, that you want to use very dry wood in the unit. If the moisture content is too high, you will wind up with a gooey mess.

The combustion process produces charcoal, which is made by burning wood in a low oxygen environment. I suppose you coud rake out the charcoal when the unit cools off, and use it for some other purpose. I will find out when my G.E.K. is up and running. If you are interested in seeing the video clips, send me your e-mail address in private, and I will forward them to you. I found them pretty interesting. Good luck with your wood gas project.

I don't have any diagrams that I can post. Apart from the videos, all I have is what is publicly available on the All Power Labs website.

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Re: Stirling Engine

BSV,

I have not done any research into this yet, but I see this works as a replacement for natural gas / propane. Since I have propane for my stove and furnace, would this work as a replacment? How does one store the gas, I assume, somehow compressed? LP is delivered as a liquid that expands into a gas for use, how do you see this working?

What is the expected cost to get your system running?

Please keep us updated as to your project. There is a Biodiesel basics thread in 17b, perhaps a wood gassification basics might fit well there too.

Thanks,

Ready

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Re: Stirling Engine

Ready:

As far as I know, there is no practical way to store the wood gas. You simply stoke the burner unit and fire it up. Within moments it produces wood gas and then you fire up your generator set. Caution: Wood gas contains carbon monoxide, so you definitely want to operate the unit outside, in a well ventilated area. I would not even think about using it as a heat source.

Alternatively, you might want to obtain Lehman's Non-Electric Catalog and look over their selection of wood burning stoves. Those are suitable for indoor use.

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Re: Stirling Engine

Propane is compressed, thats why it turns into a liquid. You would need a diaphram compressor attached to the output of the gassifier to compress it a usable gas. House natural gas is only about 0.5 psi, but it has a high flow rate at a low pressure. I have been trying to research at what pressure propane becomes liquid, but I cant find it. I read on Wiki that CO2 only turns to liquid at pressures above 5.1 atmospheres. Which is actually rather low, about 70 psi.

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Re: Stirling Engine

Ready:

Sorry, I forgot to mention the cost. If memory serves I paid about $1,400 for the Level III G.E.K. that I purchased from All Power Labs. The Level IV kit comes with all welding and painting done and all you do as assemble it. I recall the Level IV kit running around $2,200 or thereabouts.

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Re: Stirling Engine

SPM makes good points but I don't want to get that fancy. I should probably also mention that you need to be careful that your wood gas does not gum up your internal combustion engine. If done properly, I have been assured that it is clean burning and should not harm a gasoline engine.

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Re: Stirling Engine

I just watched the wood gasification 101 video series.

The problem with compression is that air is used in the process which is highly nitrogen, which doesn't compress well because of the large molecule size. In order to obtain gas that was able to be compressed, you would need to feed the system oxygen rather than sucking in air from the atmosphere.

It does not look like this would be an easy replacement for an LP tank on the homestead scale.

Rog

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Re: Stirling Engine

Well shucks! I guess you can't win them all.

I wonder if you could build some kind of scrubber to increase the oxygen content going in? I don't know anything that absorbs nitrogen other than plants.

Hey, I wonder if you had a large greenhouse. If you could feed air from the greenhouse to the input of the gassifier? I imagine you would need a very large greenhouse for it to be viable. I guess its a big what if, and moisture in the lines might be a problem.

I think all this stuff is do-able though with enough intelligent minds on board. Its time for industrial revolution #2.

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Re: Stirling Engine
SPM wrote:

I think all this stuff is do-able though with enough intelligent minds on board. Its time for industrial revolution #2.

I would have to put pencil to paper to figure out the energy requirements, etc, but you could potentially use an electric current to create Hydrogen and Oxygen from water. Feed the O2 into the system and produce a gas that could be compressed.... maybe. The Hydrogen has its own use as a store of energy as well. The only thing that makes sense at all is that the feedstock is otherwise useless biomass like twigs and stuff. It's nice to get fertilizer out too. but you would need the system to produce enough electricity to sustain the electrolysis AND provide for the original need, and this may be a stretch, seems like you would be working for your machines rather than the other way around.

Another problem is the complexity that would need to be put into place to make this all work. I'm thinking a bio-digester is a better solution for producing and storing a natural gas replacement not intended to be used in combustion engines. The jury is still out, I need more info.

Good discussion tho, sorry to hijack the original intent of the thread.

Thx,

Rog

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Re: Stirling Engine

SPM and Ready:

This afternoon, as I was mowing the lawn, I was contemplating SPMs earlier post about compressing the wood gas. It scared me. I could visualize someone storing and then piping that gas into a house and using it to run, say, a stove or oven. As I mentioned in a previous post, wood gas contains carbon monoxide. It can kill you. Natural gas is relatively benign and so is propane. Wood gas is dangerous. In a well ventilated outside location, it can provide useful energy by converting wood into electricity via a gasifier and genset. But wood gas used indoors is a recipe for disaster.

Please forgive my repetitiveness, but I worried about this all afternoon.

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Re: Stirling Engine

Yea I don't think I would put the gassifier inside.

Compression and storage wouldn't really work for a gassifier, but I think it would for a methane digester. You would however need the proper rated equipment, and obviously to know what you are doing would be the most important.

I'm just trying to get the ball rolling, thats all.

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Re: Stirling Engine

If it helps, the mineral zeolite absorbs nitrogen:

"The current state of the art in oxygen concentrators is a system based on two containers lined with zeolite, a material that absorbs nitrogen"

http://www.priorartdatabase.com/IPCOM/000021505/.

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Re: Stirling Engine

They should combine the sterling enginer with a ceramic fuel cell stack (see CFU on the asx www.cfcl.com.au) as a by-product of the electricity generation of ceramic fuel cells is heat.

A hybrid electric / gas (LPG) car could then be very effective.

The sterling enginer might be used to charge the batteries or provide lower end torque..

It could be a clever marriage of the two technologies if thought through.

This might be out of the scope of CFU, but other ceramic fuel cell companies could run with it...

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