From: Sean Breheny <shb7@cornell.edu>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Fri, 26 Feb 2021 14:48:40 -0800
Subject: Re: [EE] Low power energy measurement
Thread-Topic: [EE] Low power energy measurement
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Just an off-the-top-of-my-head idea - there are quite a few peltier-powered
fans for wood stoves available for about $30 US online. They sometimes have
long-term reliability problems but it might work well for some experiments.

You're probably aware of this but there is a fundamental thermodynamic
limit which depends on the temperature difference between the hot and cold
sides. The greater the difference, the more energy you can theoretically
extract. This is called Carnot efficiency and the formula is 1-Tc/Th where
Tc and Th are the kelvin temperatures of the cold and hot sides,
respectively. Then, beyond this, each technology for extracting said energy
has its own limitations. I would expect that for a heat source at 100 deg C
above room temp (Carnot efficiency 25%), thermoelectric generators are
going to be limited to extracting about 5% of the heat flow at best, and
about 2% is probably more realistic.

On Fri, Feb 26, 2021 at 1:38 PM Neil <picdude3@narwani.org> wrote:

> I'm trying to get a ballpark idea of how much energy I can get out of a
> small thermoelectric generator over an extended period of time.
> Anyone know of a simple circuit/project or even product I can pick up
> that would let me do this relatively easily (for now)?  I just want to
> see if an idea is viable before investing too much into this.
>
> Cheers,
> -Neil.
>
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