What is Digg?112 Comments
- Berkana, on 07/12/2009, -1/+86The Stirling cycle is Carnot-equivalent. If you'll remember from your thermodynamics class, the Carnot cycle achieves the theoretical maximum efficiency available to any engine operating off of heat.
http://challenge.bfi.org/sites/challenge.bfi.org/f ...
Unfortunately, the Stirling engine does not implement the Carnot cycle; it implements the Pseudo-Stirling cycle.
http://challenge.bfi.org/sites/challenge.bfi.org/f ...
The efficiency of a physical Stirling engine is entirely dependent on the temperature difference and the efficiency of the regenerator. There is no good way of estimating the efficiency without knowing the temperature of the heat source and the heat sink, and the heat transfer and heat capture efficiency of the regenerator.
Presuming 100% efficiency of the regenerator, the thermodynamic efficiency of a gasoline burning Stirling engine with an 80˚F heat sink is about 80%. For comparison, the efficiency of a conventional internal combustion engine is between 18% and 25%.
(FYI, I do Stirling cycle research.) - STPZ, on 07/12/2009, -1/+63Lisa, in this house we obey the laws of thermodynamics
- edm1950, on 07/12/2009, -2/+34You can always tell when humanities majors come across a neat technology, suddenly it should've saved the world. To do the things suggested here the engine would need to be the size of the house that it was trying to power as the engine is really low compression. They could prolly help power the space station as the temperature differential between space and the interior of the space station is quite dramatic but the forces generated by the cycling of the engine would probably cause more problems than the generated electricity would solve. They make good water pumps, but so does a hydraulic ram. The high pressure steam and internal combustion engines won for a very good reason.
- inactive, on 07/12/2009, -0/+28I ran across this website around five years ago in shop class. I had forgotten all about it. These animations still fascinate me!
- coondog35, on 07/12/2009, -0/+27So elegant. My favorite use I've seen for a sterling engine was a processor heat sink.
http://digg.com/hardware/Stirling_Engine_used_to_C ... - SamSks, on 07/12/2009, -0/+17Have you actually built one?
That's something I'd REALLY like to see! - cornelje, on 07/12/2009, -0/+15cause knowledge is power!
- ilikedemoon, on 07/12/2009, -0/+14Designed in 1816 by a reverend. Imagine that.
- LoudMusic, on 07/12/2009, -2/+16I fear you miss the point. The hot side is to be supplied by naturally occurring heat like geothermal or solar.
- XkenX87, on 07/12/2009, -3/+17It's Great To Learn
- Berkana, on 07/12/2009, -0/+13Rev. Robert Stirling invented the Stirling engine because too many people in his congregation were getting killed by boiler explosions. However, the problem of boiler explosions was virtually eliminated when steam engines switched from using cast iron boilers to steel boilers. At that time, the superior efficiency afforded by the Stirling engine was not enough to compensate for its inferior power density; steam engines and internal combustion engines achieve much higher compression ratios, which boost power density, whereas conventional Stirling engines only achieve a compression ratio of less than 1:2. (Internal combustion engines achieve between 1:8 and 1:12).
The reason Stirling engines fell out of favor was their low power density, but their efficiency is causing them to be reconsidered for applications previously dominated by steam and internal combustion. - wjappe, on 07/11/2009, -2/+14Check out this story on wired, in the desert they use the stirling engine on a solar project
http://www.wired.com/science/planetearth/news/2005 ... - basselope, on 07/12/2009, -0/+12Without getting into too much detail, mass production of 3KW units is happening as we speak (my company supplies components for this project):
http://www.infiniacorp.com/
Video of field-test units in operation:
http://www.infiniacorp.com/infinia-solar-system.ht ...
PDF spec sheet:
http://www.infiniacorp.com/media/2_page_spec.pdf
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Based in Washington state, I've seen these units operate well on heavily overcast days. Output was, of course, reduced, but not as much as you might think. Higher output units are in the the testing stage with production scheduled to begin in 2010. - geoboy, on 07/12/2009, -0/+10It was the 19th century, man. Back in those days everyone and their mother was an innovator.
- JUSTINS13, on 07/12/2009, -0/+9Anybody know how efficient this thing is?
- Phoyo, on 07/12/2009, -0/+8You wouldn't be able to use space as the cool side since there's nowhere for the heat to go. Unlike what you see in the movies, yes space is cold, but it's also empty so you wouldn't get any heat transfer via conduction or convection. The only heat transfer mechanism present would be radiation, which would be very slow. In this sense the space station is actually insulated from space and retains heat very easily.
- Culyt, on 07/12/2009, -0/+8Theres a cool TED talk about using mirror petals that individually track the sun and learn the best positions using AI to redirect light onto a Sterling engine created using evolutionary algorithms.
http://www.ted.com/talks/bill_gross_on_new_energy. ... - roomaustin, on 07/12/2009, -1/+9Yep. Especially the part where it's alternating from hot to cold.
- Berkana, on 07/12/2009, -0/+8What you're thinking of is a heat-driven heat-pump. Those are Vuillumier Heat Pumps, or duplex-Stirling engines. And they don't work using the heat difference in the house; they need one temperature difference to drive the pumping of heat to move heat against another temperature difference.
- FortyCaliber, on 07/12/2009, -0/+8and power is VICTORY!
- dissolutionman, on 07/12/2009, -0/+7Through victory, my chains are broken!
- howheels, on 07/12/2009, -0/+7I first saw this type of engine showcased at the Deutsches Museum in Munich. I was blown away by this, and many of the other engines they had on display. One particularly cool one was a 200k+ RPM turbine engine they had shoe-horned into a (I think) Mercedes.
- liljay2k, on 07/12/2009, -0/+6With our powers combined, we are...
- guitmusic11, on 07/12/2009, -0/+6all lathered in oil
- xjbri, on 07/12/2009, -3/+9Does this turn anyone else on?
- Berkana, on 07/12/2009, -0/+6No, it's not. The conventional Stirling engine implements the pseudo-Stirling cycle, which is not Carnot-equivalent.
Only the theoretical/ideal Stirling cycle is Carnot equivalent. Stirling engines in general do not implement the theoretical/ideal Stirling cycle.
http://challenge.bfi.org/sites/challenge.bfi.org/f ...
http://challenge.bfi.org/sites/challenge.bfi.org/f ... - Berkana, on 07/12/2009, -0/+6@singularity:
Most uses require power density more than they require efficiency. However, where efficiency is the primary requirement, stirling engines still dominate.
Stirling engines are more efficient that photovoltaics for harnessing solar power, and Stirling engines are also more efficient than nuclear decay batteries such as those used by NASA in space probes; a Stirling engine using a radioactive heat source will achieve a significantly higher power output and higher efficiency than a typical nuclear battery:
See this:
Compendium of Solar Stirling technology
http://www.osti.gov/bridge/servlets/purl/10130410- ...
Stirling engines for passive nuclear power:
http://www.youtube.com/watch?v=c_uSJl0-Wfc - pygmy, on 07/12/2009, -0/+6theyre all over ebay
http://cgi.ebay.com.au/SOLAR-Low-Temperature-Stirl ... - Berkana, on 07/12/2009, -0/+6That's not quite how a Stirling engine works.
- DirtPile, on 07/12/2009, -3/+8Dugg for saving me the time typing this.
- Berkana, on 07/12/2009, -2/+7That is not true. They are being used for solar thermal applications. So. Cal. Edison is planning on building a 500-800 MW power plant in the Mojave desert using solar Stirling engines:
http://www.stirlingenergy.com/projects.htm
Using this engine:
http://www.stirlingenergy.com/how-it-works.htm
Stirling engines have the most efficient work cycle of any heat engine. They fell out of favor during the advent of internal combustion engines because of their low power density, but during times of expensive fuel, GM and Ford both experimented with Stirling engine vehicles. In 1969, GM built experimental StirLec (Stirling Electric hybrid) vehicles, but they never made it to market because the hybrid technology back then was not mature enough.
http://www.treehugger.com/files/2009/05/gm-hybrid- ... - ThetaDot, on 07/12/2009, -1/+6Cool to see this show up here. I've been fascinated with the Sterling engine for about a year now (bought a book on building them but haven't gotten around to using it yet :[ ). My favorite commercially available sterling is made by Hog: http://www.youtube.com/watch?v=uuWubyArM8U
Really beautiful little machine.
I've never been into 'steampunk' but I can imagine anybody who likes that look would really enjoy a few of these around the house to play with. - DiggMikeS, on 07/12/2009, -0/+4I want a 3 KW one that you can buy at home depot please.
- Berkana, on 07/12/2009, -1/+5Even with a regenerator with much less than 100% efficiency, Stirling engines achieve efficiencies in the range of 30-40%. An engine running the theoretical cycle achieve efficiencies between 50-80%.
- S1ngular1ty1, on 07/12/2009, -3/+7You also have to have a hot and cold side otherwise it won't work. So if you put one of these out in the sun it won't run because both sides will be hot. That is why stirling engines aren't very useful. It is difficult to maintain a big enough temperature delta to keep them running or get much power from them.
- xs11ax, on 07/12/2009, -0/+4and the barriers built around my mind are no more!
- B1665r, on 07/12/2009, -0/+3Or even the waste heat from a coal fired steam boiler...
- wramos09, on 07/12/2009, -0/+3Very Interesting, i had no idea ICEs were so inefficient...
- shedtroll, on 07/12/2009, -0/+3Adam Hart Davis (Britian's answer to Bill Nye) did a thing about this engine. Imagine this powering other things!
- LoneWolf01, on 07/12/2009, -0/+3Mirror: http://rorr.im/digg.com/general_sciences/animated_ ...
- 0xABADC0DA, on 07/12/2009, -0/+3At least one of the big three actually field tested a car powered by a sterling engine. It got much better gas mileage and required less maintenance, but it took like 20 seconds to start up after turning the key, It was basically killed because people are so ridiculous that the 20 seconds to start up was too irritating, nevermind that you just get stuck waiting 5 minutes at a traffic light anyway.
- Nonyaz, on 07/12/2009, -0/+3Nope, that wont work. You would need to run the engine with another engine to heat or cool your house, or use the heat difference between the inside and the outside to generate electricity (until the temperature between the two equalized), you can't do both at the same time.
- dikky, on 07/12/2009, -1/+4do they use these in power plants?
- TVarmy, on 07/12/2009, -0/+2It's just a bunch of pistons going in and out, over and over. What's so sexy about cylinders going in and out of a chamber?
- Dgen_X, on 07/12/2009, -1/+3It's the crankshaft rotation that turns me on...and when I'm feeling really dirty I go for internal combustion engines
those dirty girls.... - RareSaturn, on 07/13/2009, -0/+2Cool site!
- AlyxVance, on 07/12/2009, -1/+3heat molecules?
I think you missed the memo that heat is energy and molecules are matter. - AlyxVance, on 07/12/2009, -0/+2so... you're going to pay to heat your house, and then use the heat from your house to drive a Stirling engine, you will then use the generated electricity to pay for more heat for your house?
Personally I would try more insulation. you would actually be losing energy from your house in this process - hawks58th, on 07/13/2009, -0/+2One of the best things I've seen on the web.
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