H Veeder <hveeder...@gmail.com> wrote:

> ​Unless heat is absorbed during charging and is released during discharge
> a calorimeter can't tell you if an endothermic reaction occurred.

"The heat being absorbed" is the definition of an endothermic reaction.
That's exactly what it is. Even if the energy is not subsequently released,
you can still see the deficit during the storage phase. That is to say, if
you were to charge up a battery but not later discharge it, then you would
see a deficit with no compensating exothermic reaction following that. When
you removed the battery from the calorimeter it would be fully charged up.

The only exception to this would be if the endothermic phase occurs over a
very long time and the deficit is very small. It might be too small to
detect with a given calorimeter. It might then be released as a short
burst. We can rule out this scenario for most cold fusion experiments,
including McKubre's, because the periods when there is no heat are shorter
than the continuous periods when there is heat. So the deficit would have
to be as large or larger than the positive heat release.

> You also need a-priori knowledge of how the energy is stored.

No, you don't. Energy is energy. All energy in all forms is either stored
or it converts to heat. Because entropy.

> The calorimeter by itself only tells you that there was a mildly
> exothermic reaction followed by more intense exothermic reaction.

No, the two would have to balance in intensity if they were roughly of the
same duration. As I said in most cases endothermic phase would have to be
shorter so it would be more intense and easier to measure.

> Charging a battery is endothermic because it absorbs *electrical* energy,
> not because it absorbs *heat* energy.

Other reactions that absorb heat energy (or any other form or source of
energy) show a similar pattern in a calorimeter. For example, reactions
that absorb laser light energy will also show a deficit -- assuming you
measure the laser input correctly, which can be tricky.

A battery happens to be a convenient way to demonstrate this but any
endothermic reaction will do.

> If a calorimeter were good at detecting all types of endothermic reactions
> then you could substitute them for volt meters.

Well, a watt meter, not a volt meter. Yes, you can, and the instrument
makers do. All high-quality, high-powered wattmeters use calorimetry. That
is to say the heat up a resistor wired in series with the load, measure the
temperature and convert that to power. This method eliminates any
possibility of exotic waveforms or extremely rapid changes in electric
power being missed by the instrument. This method detects every joule of
electricity, no matter what.

- Jed

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