shivering materials?

[Sho'Nuff]

The past few days I have been reading about the home heating oil prices in the U.S. and it got me thinking about some alternative ways of heating a small structure or supplementing a main heat source without the use of oil, gas, or other fuel. I am of course aware that solar technology is currently employed for this purpose, but for the sake of a mental exercise I have been trying to think of a new solution.

After freezing my butt off getting the newspaper outside (it was ~20 degrees last night), it dawned on me that it if it were possible to develop a material that emulated our bodies natural tendency to shiver when cold, that effect could be used to drive some form of a heat generation system, e.g., one based on friction.

Now, the idea isn't as proposterous as it might sound at first. Indeed, microwave ovens generate heat via a similar principal, except that instead of macroscale vibration and friction, it is based on atomic and small molecule scale vibration and friction.

That said, is anyone aware of a material that reversibly flexes, or "shivers" in response to temperature change?

 

[Gibsons]

You want something that releases heat as it gets colder?

 

[PottedMeat]

How are you going to get energy into it? Or is it something that stores energy during the day and releases it?

Piezo elements 'vibrate' I guess, but you obviously have to put electricity into it. Maybe it could rub up against something. But thats probably not more efficient than any resistive heater.

 

[Modelworks]

Bimetallic strips move with temperature changes, but thats only one direction at a time.
I don't know of anything that will move back and forth without something else acting on it besides just temperature.

 

[PolymerTim]

As PottedMeat suggested, I think the thing that you are overlooking is the input source of energy. In your body, the muscles are producing heat when they shiver because of the work they are doing, which requires energy in the form of calories. Even if you did find a material that shivers as it cools, it could not possibly produce more heat than the loss of heat that caused the shivering or you would have just invented a perpetual motion machine (small problem with laws of conservation).

It's a nice thought, but I think it has a fundamental flaw. To tweak your question, I think it would be more appropriate to ask for a system that creates heat more efficiently with the energy it is given compared to traditional resistive or combustion heat sources.

 

[CycloWizard]

The short answer is: no. Materials thermally strain depending on their coefficient of thermal expansion at the temperature in question. There would be no driving force for a fluctuating thermal strain, which is essentially what you describe. Like Gibsons hinted, this would take an energy source, which is not readily available when you're out in the cold.

PottedMeat mentioned piezo elements, which could be useful. These systems vibrate not only due to electrical stimulus like he mentioned, but the effect is actually reversible. Therefore, if you mechanically stimulate the element, it will produce a voltage. In other words, you could walk on a quartz sidewalk and use that to power a heater. It likely wouldn't be nearly enough to heat anything to the point where you could actually tell a difference, but in principle it would wrok.