Convection I'd have thought.
As the base is touching the fire the main heat source would be conduction wouldn't it?
Anyway, more details here: http://www.ecofan.co.uk/technical-information.html
dpack
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i looked it up with nick's help above.
conduction makes 2 different semiconductors hot ,that drives an electron flow across the junction where they meet, each has a wire that goes to the motor, that current drives the fan.
very simple but rather clever
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jamanda
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But a bit more complicated than I thunk. I assumed it would be like the tin foil fans we make at work and hang over the Bunsens.
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Nick
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But a bit more complicated than I thunk. I assumed it would be like the tin foil fans we make at work and hang over the Bunsens. |
Nope. It doesn't need hot air. It needs hot contact to generate electricity.
dpack
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there are a few examples of the two types being used in a practical way.
gas radio was part of the gas companies' fight back against domestic electrification ,they had cooking and lighting ,even fridges but radio was an electric thing most folk wanted and battery radios were very limited in amplifier power and batteries need swapping every few days so a gas radio could stop them getting electric and converting everything else . gas radio uses a single semiconductor hot at one end and cooled by fins at the other to drive the electron flow (same principle as the soviet paraffin radio sets).
the thermo-electric power units of early space satellites was similar but with heat from plutonium decay as the primary energy input on the hot end and the fins cooled by ir radiation into space. fun but not ideal at home.
before decent battery tech the same principle was used as a compact ,light power supply to run the targeting and steering electronics of some missiles with the heat coming from the solid fuel motor (and / or pre heating before launch ), and if they only need to work for a short time a heat sink does the cold end job , i dont know if it was used on bigger stuff that needed to fly for a while . im not sure if the two semiconductor type has been used for this but it could be.
these are a bit more advanced than the hot/cold sort in that the properties of the two different sides of the semi conductor unit have different free electron pressure at the same (quite warm ) temp and so don't need a cold part therefore being perfect for a stove fan
very very tidy for somebody to find a "simple" hi tech solution to making a low tech thing like a wood burner work far better.
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Hairyloon
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I'm a little surprised at how thin on the ground are Stirling engines for this kind of application.
I've got one made principally out of cardboard and milk bottle tops. Obviously no good for a stove top, but it establishes the principle and the simplicity.
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dpack
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stirling engines are another rather neat bit of tech but nowhere as tidy as these wee things
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Hairyloon
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stirling engines are another rather neat bit of tech but nowhere as tidy as these wee things |
Tidiness is overrated.
vegplot
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I'm a little surprised at how thin on the ground are Stirling engines for this kind of application.
I've got one made principally out of cardboard and milk bottle tops. Obviously no good for a stove top, but it establishes the principle and the simplicity. |
They're more expensive presumably because of their relative mechanical complexity compared to solid state versions.
Hairyloon
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I'm a little surprised at how thin on the ground are Stirling engines for this kind of application.
I've got one made principally out of cardboard and milk bottle tops. Obviously no good for a stove top, but it establishes the principle and the simplicity. |
They're more expensive presumably because of their relative mechanical complexity compared to solid state versions.
Arguably they are no more complex, but they cannot be simply assembled from off the shelf components and simple castings.
Nick
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I'm a little surprised at how thin on the ground are Stirling engines for this kind of application.
I've got one made principally out of cardboard and milk bottle tops. Obviously no good for a stove top, but it establishes the principle and the simplicity. |
They're more expensive presumably because of their relative mechanical complexity compared to solid state versions.
Arguably they are no more complex, but they cannot be simply assembled from off the shelf components and simple castings.
Do they have more moving parts?
dpack
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i recon a basic version could be adapted from a V or flat twin cylinder motorbike engine ,the magneto and a few bits of pipe.
ed ps im not manhauling that sort of thing around just to charge my phone and headtorch
a bi semi rig with a small "black box" to give a usable voltage could be a very toteable couple of hundred grams, certainly smaller than suitable ,current generation, pv panels with control gear and it works while you cook/make coffee etc even in a arctic winter or thick jungle
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Treacodactyl
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If ALDI don't restock, you can get one for the same price here:
http://www.warriorstoves.co.uk/Catalogue/Fireside/Heating-Accessories/Stove-Fan-2-Blade-ELITE-19cm-Compact-Various-Finishes
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Thanks for that. My Aldi sold out of 30 in a few minutes.
Does anyone know if some makes are better than others? I don't mind paying more for one that'll move more air around.
dpack
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there might be some pointers here there was rather a lot to go through it and pick a good un.
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dpack
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what ever make of fan i recon it needs this type of chip rather than the sort found in solid state wine coolers etc which are not suitable for power gen or hot places
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Ty Gwyn
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there might be some pointers here there was rather a lot to go through it and pick a good un. |
There`s sure a big difference in prices there.
dpack
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there might be some pointers here there was rather a lot to go through it and pick a good un. |
There`s sure a big difference in prices there.
yep ,my next thought is that if the aldi ones work and they do'nt restock looking online for the same model might be a good idea. with a lot of "non brand"stuff they make loads and various folk sell em.
Hairyloon
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what ever make of fan i recon it needs this type of chip rather than the sort found in solid state wine coolers etc which are not suitable for power gen or hot places |
At that price, Aldi can't be making much.
Ty Gwyn
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what ever make of fan i recon it needs this type of chip rather than the sort found in solid state wine coolers etc which are not suitable for power gen or hot places |
At that price, Aldi can't be making much.
Don`t know,cheap enough when imported by the thousands from China.
Hairyloon
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what ever make of fan i recon it needs this type of chip rather than the sort found in solid state wine coolers etc which are not suitable for power gen or hot places |
At that price, Aldi can't be making much.
Don`t know,cheap enough when imported by the thousands from China.
Hong Kong appears favourite.
Nick
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Stuffs made in Mainland china and sold via Hong Kong often. No idea why. Tax or language barriers would be my guess.
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dpack
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iirc tax and language and the residual trade/traders links from 100 yrs of colonialism and it has a very nice deep water harbour in a convenient place.
ps the proper chips are probably a couple of quid each if one gets a big box of em, same for the castings and motors . at a guess aldi as last link in the chain make a fiver tops on them but say 20000 x £5 is worth doing and a stove fan for £25 seems a good deal compared to some of the online prices for the things.
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Hairyloon
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Arguably they are no more complex, but they cannot be simply assembled from off the shelf components and simple castings. |
Do they have more moving parts?
They do, but complexity is not just about moving parts: is a silicon chip complex?
And an electric motor is quite a complex bit off engineering, but they are made by the billion for multiple applications.
Nick
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No, but as a relating engineer, it's almost always moving parts that let you down. A chip is simple for the owner. They don't tend to fail. Motors do.
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john of wessex
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The explanation I have seen of Lidl's business model is that the suppliers don't make a large profit, BUT the numbers they buy are huge and unlike the 'non discount' supermarkets they don't muck the suppliers about, so they are keen to do business with them
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Dee J
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thanks, i had wondered if it was a similar principle to stalin's paraffin radios with a hot bit and a cool bit but it is different semis at the same temp... |
Next question: are they reversible? If you spin the fan, does it pump heat across the junction?
i dought it as that sort of stuff often has diodes but if not the semis might get over warm at the junction and possibly break .
They are reversible to a degree. The Peltier effect semiconductor device used to generate the electricity is of the same basic type as the unit in an electric cool box... when an applied voltage does indeed make one side hot and one cool (ie pump heat) the applied polarity controls the heat flow direction. So on the stove fan.. if you spin the fan the motor will act as a dynamo and the Peltier unit will pump heat....
Mistress Rose
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Silicon chips, by the time they get into something, either work or they don't. The failure is at a far earlier stage. I used to work with them, and sometimes they do, but only usually if you are working with them bare and doing things like putting on wire bonds to connect them to the outside world, or putting too much current or voltage through them. I once had to clear a 'gate' on one at 400x magnification with a human hair so we could carry on a test. After that I needed a coffee to recover as such concentration.
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Hairyloon
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No, but as a relating engineer, it's almost always moving parts that let you down. A chip is simple for the owner. They don't tend to fail. Motors do. |
Well there's a challenge: a chip that blows air without a motor... I think I'll pass.
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