[mikeclegg123]

Hey Everyone.

Does anyone know of a solution/liquid/mix of anything, that when shaken heats up? I am thinking Viscous Dissipation, where the friction heats the substance up. As other wise it is a one time reaction. What Im looking for is something that can be shaken over and over again, heating each time. Are there certain solutions which heat when shaken more so than others?
Im thinking something that increases to 50 degrees in about a minute of shaking. Im trying to prove something to a friend of mine.

Any ideas would be welcome.

Cheers,

Mike

[curiouscat]

I'd choose a high viscosity fluid & a narrow geometry..

[curiouscat]

More precisely perhaps, go for a high Brinkman number.

i.e. In addition to high viscosity go for low thermal conductivity. In hindsight seems kinda obvious but still.

[mikeclegg123]

I'd choose a high viscosity fluid & a narrow geometry..

By narrow geometry are you referring to what the fluid is held in when it is shaken?
Are you aware of a class of fluids that have these kind of properties, rather than just high viscosity?

Cheers,

[curiouscat]

I'd choose a high viscosity fluid & a narrow geometry..

By narrow geometry are you referring to what the fluid is held in when it is shaken?

Yes.

You might have more luck by forcing through a narrow channel than just shaking. Besides 50 C in one minute of hand shaking sounds a bit high. Not sure if you'll find anything that high.

I'd try various high viscosity lubes. Polymer melts might be another thing to try, but more exotic.

[curiouscat]

Not sure why you say "not just viscosity". Viscosity is what will mostly matter here. I think.

Its like asking, can you suggest a heavy material but not just something that has a high density.

[mikeclegg123]

I'd try various high viscosity lubes. Polymer melts might be another thing to try, but more exotic.

Do you have any resources you can point towards for Polymer Melts? All I seem to be able to find on Google is not exactly relevant to this.

Cheers,


EDIT: Fixed quoting typo

[mikeclegg123]

I'd choose a high viscosity fluid & a narrow geometry..

By narrow geometry are you referring to what the fluid is held in when it is shaken?

Yes.

You might have more luck by forcing through a narrow channel than just shaking. Besides 50 C in one minute of hand shaking sounds a bit high. Not sure if you'll find anything that high.

I'd try various high viscosity lubes. Polymer melts might be another thing to try, but more exotic.

Do you have any resources you can point towards for Polymer Melts? All I seem to be able to find on Google is not exactly relevant to this.

[curiouscat]

http://www.ptonline.com/columns/where-does-shear-heating-occur-heres-how-to-find-out

Like if you force viscous molten polymer through an extruder I bet you get a lot of temperature rise.

[Enthalpy]

Not shaking by hand I hope? Because it needs much work to produce little heat.

I braked 50kg from 120km/h hydraulically, and after a dozen cycles, the liquid (<1L) got perceptibly warmer. This kind of energy isn't accessible by hand.

If really your arms are the source of work, you should minimize the amount of liquid. Like, rotate a brace
http://en.wikipedia.org/wiki/Brace_(tool)
that you apply strongly to let small steel parts rub against an other, and add few drops of water that you observe boil.

Just to give an idea: a good cyclist provides 200W, over one minute it's 12kJ, which heats 57g of water by 50K. How much do we produce with the arms on a brace: 10W? And by shaking: <1W?