# The Naked Scientists Forum

### Author Topic: What happens if you boil a kettle in microgravity?  (Read 10592 times)

#### chris

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##### What happens if you boil a kettle in microgravity?
« on: 09/03/2008 09:42:53 »
What would happen if you were to boil a kettle ("put t' kettle on" to harp back to an existing joke elsewhere on the forum) aboard the International Space Space Station i.e. in microgravity?

When a kettle boils the hot water forms bubbles of vapour which, being less dense than the surrounding water, rise up the liquid, cool and then collapse on themselves. So what would happen in space where there is no up and down?

Chris

#### Soul Surfer

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##### What happens if you boil a kettle in microgravity?
« Reply #1 on: 09/03/2008 10:38:38 »
Interesting concept!  You can get large blobs of water held together by surface tension in zero gravity.  let us assume we put one of these onto an electrical wire with a resistor in the middle of it to act as a heating element.  The surface tension should keep it attached and reasonably stable.  This could also be contained in a vessel but thats not the major part of the experiment.  Applying current would heat the water locally to the resistive element.  As there is no gravity there would be no convection so heat distribution can only be by conduction and radiation.  This is a much less efficient process so the water would heat up and eventually vapourise near the heating element putting a bubble of vapour close to the element.  This again would stay in position and create an even less efficient path for heat flow because gases are quite poor conductors of heat so the temperature of the resistive element would rise rapidly until the heat loss by radiation created a stable equilibrium.  Possibly the element would glow red hot.  so there you would have a red hot filament surrounded by a transparent bubble of steam inside a blob of water.  A lot of the radiation would pass easily through the transparent steam and water so the whole thing could be stable.

#### lyner

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##### What happens if you boil a kettle in microgravity?
« Reply #2 on: 11/03/2008 11:45:09 »
What SS says must be right but, if you used typical kettle size and power, I reckon it would probably produce enough local boiling to blow all the water out and then melt the element. The surrounding water would, I think, absorb enough energy to cause more boiling despite the surrounding steam.
You could almost mimic the situation with a model. A boiler, consisting of a very thin  (flat) horizontal cylinder would suppress convection and the heat would transfer in much the same way as in microgravity.
I should leave the room before switching on the power!

#### turnipsock

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##### What happens if you boil a kettle in microgravity?
« Reply #3 on: 11/03/2008 14:05:09 »
It's a good question.

Even filling a kettle would be a challenge. My guess is that the water is in some sort of bag which you could microwave, or just stick outside for a bit and let the sun warm it up.
« Last Edit: 11/03/2008 20:04:25 by turnipsock »

#### lyner

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##### What happens if you boil a kettle in microgravity?
« Reply #4 on: 11/03/2008 15:20:54 »
All you need to do is stir it up and local boiling wouldn't happen. I guess the primus stove wouldn't work too well either. . . .

#### syhprum

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##### What happens if you boil a kettle in microgravity?
« Reply #5 on: 11/03/2008 16:32:00 »
An interesting point, does the ISS have any equipment for producing coffee

#### turnipsock

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##### What happens if you boil a kettle in microgravity?
« Reply #6 on: 11/03/2008 20:08:44 »
All you need to do is stir it up and local boiling wouldn't happen. I guess the primus stove wouldn't work too well either. . . .

They might set fire to the place, it would be funny watching them trying to use a fire extinguisher though.

#### techmind

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##### What happens if you boil a kettle in microgravity?
« Reply #7 on: 17/03/2008 19:25:01 »
An interesting point, does the ISS have any equipment for producing coffee
And are the Russians allowed a supply of vodka?

#### chris

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##### What happens if you boil a kettle in microgravity?
« Reply #8 on: 06/04/2008 10:20:34 »
Here's a nice image of the apppearance of water "boiling" in microgravity:

The problem of what happens when water is boiled in space is well analysed and explained in this article (which is also the origin of the above image):

It's a really interesting question.

Chris

#### syhprum

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##### What happens if you boil a kettle in microgravity?
« Reply #9 on: 06/04/2008 11:10:38 »
I believe the Russians are allowed a small supply but the dedicated Americans would of course decline if offered any

#### chris

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##### What happens if you boil a kettle in microgravity?
« Reply #10 on: 06/04/2008 16:18:19 »
Yeah, they'd be too busy with their hashcakes to want any vodka

#### lyner

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##### What happens if you boil a kettle in microgravity?
« Reply #11 on: 07/04/2008 10:54:33 »
Great pictures!
Natural convection is very useful in Earth n'est pas?

#### chris

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##### What happens if you boil a kettle in microgravity?
« Reply #12 on: 08/04/2008 09:14:47 »
"n'est-ce pas" - just being picky...!

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##### What happens if you boil a kettle in microgravity?
« Reply #12 on: 08/04/2008 09:14:47 »