Re: Thermal Inductance

Thanks for your response, as there have been very few in this (and other
newsgroups). I am asking others about their knowledge of any cases of
thermal inductance being observed, because it is one explanation for an
event that I experienced about 20 years ago. I'll briefly describe the
event.

I was holding a 6 foot long piece of rebar (about 1/2" diameter steel rod,
commonly used to reinforce concrete) at arms length while a friend I was
helping was cutting it in half with an oxy-acetylene torch (I think steel
melts at ~1400 C). It was cut in half and both ends were brightly red hot.
After cutting, I moved my hands towards the ends to hold one 3 foot piece in
each hand at the cool end. There was a D-shaped tank (about 12" wide, 3
feet long, 2 feet high, flat of D facing up) filled with water nearby, about
2 inches from the top. So I dipped one of the hot ends in the water
gingerly a few times to cool it at about a 30 degree angle from the floor.
I didn't want to make a lot of steam quickly, as I thought that rapid
cooling might alter the metal somehow and my friend was going to weld the
two pieces to a piece of angle iron afterwards. The steam ball made was
about 4-6 inches in diameter at most as I recall. Within 15 seconds or so,
the 3 foot rod I was cooling became so hot that I couldn't hold it anymore,
so I dropped it into the tank. I was still holding the other rod in my
other hand (still glowing red hot) and it was only slightly warm where I
held it. I cooled it off too and we went about the next step of welding the
two pieces to the angle iron.

I do not have access to a torch or rebar to recreate the event since then,
but I've often thought about what I experienced ever since. I wonder if I
experienced thermal inductance, analogous to an inductive kick in
electronics. I still wonder about it and would appreciate any considered
explanations you may have (or others in this group).


"Helmut Wabnig" <EmailAddress> wrote in message
news:mlq1g1tjhlfn22ekeotb1sa906isfij694@xxxxxxxxxx
> On Mon, 15 Aug 2005 13:30:50 -0500, "s.morra" <s.morra@xxxxxxxxxxx>
> wrote:
>
>>As an example, from page 34 of
>>http://web.mit.edu/2.151/www/Handouts/EnPwrFlow.pdf (other references easy
>>to find)
>>
>>"Thermal Inductance: No significant physical phenomenon has been observed
>>which corresponds to energy storage due to heat flow in a "thermal
>>inductor".
>>Thus only one thermal energy storage element, the thermal capacitance, is
>>defined."
>>
>>and of course, we have thermal resistance.
>>
>>So it appears that thermal resistance and thermal capacitance but no
>>thermal
>>inductance phenomena have been observed. Does anyone know of any cases
>>where thermal inductance has been observed?
>>
> let us have a look at the characteristics of a capacitor:
> (fixed pitch font)
> A stepwise increase in Voltage (temperature)
> will result in a slowly decreasing current
> (a certain resistance assumed in the conductors)
>
> Voltage difference (temperature difference)
> _______________
> I
> I
> I
> ----I
>
> Current (Ampere, calories per sec)
> *
> I *
> I *
> I *
> ---- *
>
>
> For an inductor we expect the following characteristic
>
>
> Voltage (temperature)
> _______________
> I
> I
> I
> ----I
>
>
> current (calories per sec)
> *
> *
> *
> *
> *
> ----*
>
> How can we possibly make such an object?
>
>
> w.
>


.

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