[Stoves] radient heat capture, total heat measurement

[ajheggie at gmail.com]

On Tue, 6 Mar 2012 07:47:03 -0800, Richard Stanley wrote:

>If radient energy is the mother and conductive convective "heats" are added expressions of it,  then why does one rely only upon measurement of thermal heat only in these more tangible but not necessarily more influential bands of the spectrum,  as the standard  measure of cooking efficiency ?

I suppose it's to do with what means we have of producing the power to
do the cooking, fire is the easiest way of liberating the energy and
transferring it to the cooking pot. Plants have concentrated sunlight
into wood.

Light can plainly be used for heating, didn't one of the ancient
greeks write of the concentrated beams reflected from polished bronze
shield setting fire to ships rigging?

>Micro waves in themselves are not "hot" but they do a wonderful job of heating by disturbing molecules, just as the visible band of radiation we call heat, does. 

Presumably there was no evolutionary advantage in having an organ that
can sense infra red in the same way eyes interpret light but many
animals do have increased sense of warmth, snakes can hunt by it.

Microwaves for cooking have only become commonplace in the last 60
years  but the principle is the same as other means of heating, they
selectively excite water molecules. The microwave radiation is tuned
to deliver in frequencies which water molecules will accept in
discrete amounts, otherwise they would just pass straight through.

>My naked supposition is therefore, that beyond a normal thermometer or one measuring just IR, one needs a more comprehensive "molecule disturbing"
>measurment device 

A thermometer is something that reacts to change in temperature, it
doesn't measure the activity of molecules but rather compares the
effect the molecules have on a substance.

I don't think it is possible to directly measure the state of a
molecule without changing it.

AJH