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Eco Fan


mrsmelly

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18 minutes ago, WotEver said:

About the kettle? Remove the toy fan and replace it with a stage weight. Any old heat sink will have the same effect. 

Of course, but in your case the heat is stored within the mass of the 2kg weight, which, once up to temperature, stops absorbing any more. Where is the same heat going when absorbed by the .5kg mass of the ecofan?

I await your alternative facts.

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30 minutes ago, carlt said:

REPORTED!!!! 

I've been called some stuff on this forum but this is a new low!

Then again...a gentle Trump would move more warm air than an Ecofan.

Oh no! I'll get banned by Teach! Then where will I go for intelligent boaty talk, where I can accuse someone of being a Trump with impunity?

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2 minutes ago, carlt said:

Of course they did.

Placed next to the burning witch it warmed the baying mob.

In the directors cut ( which was banned in 7 countries) the ecofan actually took off and sliced some of the baying mobs ears and noses off quite graphically.

The graph was used by Calfarm as evidence of the ecofans performance. 

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1 hour ago, Jim Riley said:

Of course, but in your case the heat is stored within the mass of the 2kg weight, which, once up to temperature, stops absorbing any more. Where is the same heat going when absorbed by the .5kg mass of the ecofan?

Into the air above the stove via the fins on the top. 

Just as it would if the toy fan wasn’t there. 

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10 minutes ago, WotEver said:

Into the air above the stove via the fins on the top. 

Just as it would if the toy fan wasn’t there. 

Assuming Jim meant "why does the fan have a continuing effect on the kettle whereas the weight would affect it only while heating up"; the answer is in the law of conservation of energy. Whether put to any useful purpose or not, the mechanical energy of turning the blades comes from a loss of heat from the stove, the stove will continue to be cooler while the fan turns.

I am surprised that the effect is strong enough to prevent the kettle boiling but if it is, then it is.

Edited by frahkn
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1 minute ago, frahkn said:

Assuming Jim meant "why does the fan have a continuing effect on the kettle whereas the weight would affect it only while heating up"; the answer is in the law of conservation of energy. Whether put to any useful purpose or not, the mechanical energy of turning the blades comes from a loss of heat from the stove, the stove will continue to be cooler while the fan turns.

The amount of Energy used to spin the fan is insignificant. The loss of heat from the top plate comes from dissipating it through the heat sink fins on the top - it’s what they’re there for. 

With the heat gradient across the peltier chip on one of those toy fans perhaps an optimistic 5% is converted to electrical energy. The other 95% is dissipated through the fins. 

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Just now, ditchcrawler said:

Into the room making the heat transfer from the stove to the room more efficient

It can’t be more efficient if it’s transferring the heat that’s already on the top plate which would have been dissipated into the space above the stove anyway. All it does is move the heat transfer vertically by the height of the fins. 

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15 minutes ago, WotEver said:

The amount of Energy used to spin the fan is insignificant. The loss of heat from the top plate comes from dissipating it through the heat sink fins on the top - it’s what they’re there for. 

With the heat gradient across the peltier chip on one of those toy fans perhaps an optimistic 5% is converted to electrical energy. The other 95% is dissipated through the fins. 

Of course but the fan and the weight are the same in that respect - masses of metal which heat up, radiate part of that heat, reach the same temperature as the stove top then stop getting any warmer as they are radiating as much energy as they receive. The only thing different is that the fan has a secondary 'outlet' for energy which it receives.

As I said in my edit, I am surprised this is sufficient to affect the kettle but we can't ignore the reported experimental evidence that it does. I am not on the boat at the moment so cannot try to repeat the experiment and anyway I don't think my stove top is big enough for the fan and a kettle.

Perhaps it would be useful to see if the presence of the kettle (while it is still heating) slows down the fan.

Edited by frahkn
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1 minute ago, frahkn said:

The only thing different is that the fan has a secondary 'outlet' for energy which it receives.

No, that isn’t the only difference. The difference that is affecting the kettle is that the heat has been removed from the top plate and transferred to the fins. 

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2 minutes ago, WotEver said:

No, that isn’t the only difference. The difference that is affecting the kettle is that the heat has been removed from the top plate and transferred to the fins. 

Sorry, I don't understand.

The fins (indeed every part of the fan) eventually get hot and transfer heat to the room. But so does the metal weight. Admittedly the fan will always be hotter at the base than at the top, it must be to work. But so will the metal weight. I don't see why both fan and weight cannot be treated as just 'masses of metal'.

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Because the heat is being transferred vertically away from the top plate to the top of the fins. That is the purpose of the fins - to dissipate the heat as fast as possible in order to create the heat gradient. Doing so obviously cools the top plate which prevents your kettle from boiling. It doesn’t create any extra heat so the heat leaving the fins has to have come from the top plate. It doesn’t make the room any hotter because it’s not affecting the burn rate of the stove. 

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I used to put a flat iron on the hot plate which stopped the kettle from boiling enabling me to be good to my word when I told folk "The kettle is always on".

When the iron was removed the kettle reached boiling point within seconds.

The flat iron was also extremely effective at distributing the heat throughout the cabin (well just as effective as the Ecofan anyway).

 

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3 minutes ago, carlt said:

The flat iron was also extremely effective at distributing the heat throughout the cabin (well just as effective as the Ecofan anyway).

You could run down to the other end of the boat with it, distributing its heat throughout the boat’s length. Then run back and heat it up again. Not only would it have more effect than an Ecofan but you’d be getting your daily exercise to boot. 

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8 minutes ago, carlt said:

I used to put a flat iron on the hot plate which stopped the kettle from boiling enabling me to be good to my word when I told folk "The kettle is always on".

When the iron was removed the kettle reached boiling point within seconds.

The flat iron was also extremely effective at distributing the heat throughout the cabin (well just as effective as the Ecofan anyway).

 

At least you could pick the iron up and move the heat somewhere else until it went cold.

Edited by Rob-M
Should have read wotever's post first.
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