Transparant Heating Elements !

[insane_alien]

hmm could you use an infrared laser to heat the toast? it passes through the glass and somehow gets refracted onto the bread and then heats it?

[qwerty123]

ok , if i did use the wire solution , is there any other see through material that i can use instead of glass , something that conducts heat better than glass and maybe even allows more raditation through aswell ?

 

Thanks

[insane_alien]

diamond is theoretically possible, finanicially impossible though. there a various plastics and high conductivity glasses as well.

[qwerty123]

ok

 

Thanks

[insane_alien]

i've been looking about and your best bet would still be with a hot fluid running through the glass.

 

there are some electrically conductive glasses in development which would mean you could use the actual glass as a heating element but they look to be a wee while away just now.

[qwerty123]

how about you just have one sheet of glass , then on the side of the glass were the toast goes i just put the cables in then they are directly exposed to the toast ? This would mean i wouldnt need to bothe with special heat conducting glass ! Then i could put a heat resistant layer to protect whoever uses it from the glass . You think this wire would take enouh current to cook toast without burning out ?

 

Thanks

[insane_alien]

but what about toasting both sides at once?

[qwerty123]

well you could just do the same on the other side , bit like what that other toasters like. But there would quite a big problem of heat escaping thru the top AND the sides

[qwerty123]

i been looking about on google . Im not being lazy ! but if anyone knows somewhere were i can find some ultra thin wire that would be suitable for heating then please do let me know !

 

I will kep on looking hopefulyl something will appear !

 

Cheers

[5614]

When I originally posted about the ultra thin wires it was with respect to clearing a bit of water vapour from a windscreen.

 

Toasting bread takes a lot more energy. Those thin wires wouldn't do the job. They do not produce enough heat to toast bread, unless you leave them on for a very long time. And obviously you can't just crank up the current on the thing wires, because they would easily melt.

 

This is why toasters use thicker elements with much high currents.

[Rocket Man]

what about a hybrid between ideas, use a double glaze with salt solution in between. the salt solution is transparent and if it can be held without any room for expansion it wont boil either.

simply run this as the resistor/element.

 

another idea is a bit over kill, use magnetic induction to heat the water in the bread

place the bread in the centre of a coil and link to high currnet AC.

[qwerty123]

so you simply run the curent throuugh the solution ? I dont really understand ? Never herd of this before ?

[insane_alien]

sounds good but you would have to top up the salt every now and then as it is electrolysed out from the current.

 

in addition, you have to account for pressure build ups (either to gases or solid build up fom the salt) and the fact that it will have a limited lifetime(maybe around 10000-100000 uses) also because of waste buildup and the electrodes dissolving/reacting which they would eventually do.

[qwerty123]

what sort of heat could this give of ?

[insane_alien]

depends on the rate of conduction through the glass and its melting point. also on the boiling point of the solution although that can be controlled with pressure but then it starts getting chunky and ridiculously heavy.

[qwerty123]

What sort of pressure do you think the salt solution would need to be under ? Obviously i do not want anything exploding with hot salt solution in it !

 

Could it possibly be hot enough to toast bread anyway

 

This all probably explains why the thin oxidised layer of metal is the better way ?

[insane_alien]

i'm not too sure what pressure it would have to be under but i still prefer a circulating fluid since you can then use a fluid that won't boil within the temperature range. thermal expansion is easier to counter than a phase change. it also eliminates some problems that a conducting salt solution would throw up.

 

incidentally does anyone know what temperature bread toasts at?

 

EDIT: ok so i've been looking around and i've found some values. i appears that the reaction starts around 155*C so we'll probably be looking at a fluid temp of around 200 *C this means water is a no-no sin it would require it to be at a pressure of 16 bar which would be dangerous if the toaster fell since it would shatter and explode from the fact that the water suddenly expands to 2000 times its origional volume.

 

some sort of oil is probably in order here.

[YT2095]

use peanut (groundnut) oil, it easily takes those sorts of temps and higher before it tries to vaporise, and as it would be a sealed unit there`s worry of oxidation over time, and IF there was ever a leak, it`s perfectly edible too

 

even regular cooking oil in a chip pan will make chips and toast bread, Peanut oil can go even Hotter than that!

[insane_alien]

awesome YT. i was looking around for fluids like that earlier i even considerded liquid metal alloys on the premise that they'd look damn awesome. the thermal expansivity might start being a problem but an 'air' gap would probably sort it out.

 

air is in brackets because its more likely to be either a vacuum or an inert gas rather than air.

[YT2095]

well the way to do it would be to have your glass sandwitch held together with your frame that makes the seal (just like a double glassed window pane).

at the bottom inside you have your heating coil in the oil with a bi metal thermostat that cuts the power when it`s up to temp. then you fill with the cold oil and heat it just above Max temp, and Then finish the seal.

allow to cool and away you go, thats One side done

 

that way at No Time is there ever positive pressure, only a little negative when cold, but there`s no Implosion risk as the viscosity of the oil would preclude this action by energy absorbtion, not only that, but peanut oil doesn`t expand all that much anyway.

 

oh yeah, and having the heater coil submersed in the oil, it`ll last forever!

[Rocket Man]

brilliant! YT,

also, the oil isnt too viscous that you dont get convection.

do you have any figures on the thermal densities? you may find it takes too long to heat up sufficiently. also, the peanut oils i've seen are yellow, is there any way of getting a bleaching effect?

 

it'll need a warning label, "warning, do not smash when hot"

[insane_alien]

you would be better pumping the oil round a circuit than relying on convection you could achieve a better heat transfer rate with thinner glass and less oil

[qwerty123]

so you dont think that just heating up the reserve of oil inbetween the pains of glass would create enough heat ? This is going to be obviously running of a mains power supply .

[insane_alien]

it would in theory. but you wouldn't get the best possible heat transfer.

[qwerty123]

ok suppose that does make sense. I just been looking at the peanut oil just on like google imges and stuff and it is a yellow collour like Olive oil. Im gathering its always this colour , is there anything else that is completely clear that would do the trick ?