You can't afford it !!!

[Magnus Danielson]

From: harry <harrybissell at prodigy.net>
Subject: Re: You can't afford it !!!
Date: Thu, 28 Dec 2000 23:15:34 -0500

> Thermal inductance...  I don't think so (or can't think of a case)

Me neither, but it is an interesting concept if it exsited, right?

> Your thermal capacitance is actually a time lag in thermal response
> yes... which you are thinking of as capacitance ???

Thermal capacitance is the ability to hold heat energy, together with
the termal conductance you get the RC lag network.

> So what you are asking for is something that conducts heat 'faster'
> but faster than what.

No, it's worse than that, I'm asking for something transfering the eat
in the wrong direction!!! It must transfer the heat in the opposite
direction than that of the thermal capacitance, that is, when exposed
to a temperature gradiant it will deliver more heat to the hotter end
than to the colder end. Very obscure material indeed.

If I only wanted to conduct something faster, then I would choose a
rod of material having a diffrent ratio, diffusion speed, time
constant and put that in parallell, just like putting an RC link with
much lower time constant in parallell with one having a high time
constant.

Now, the only thing that come close is superfluent Helium. Take your
average tank of Helium, just stuff it into the freezer until you gone
below 2.17 K and you can start to play! The reason it works is since
the normaly liquid helium has entropy and superfluid helium does not
and the floating helium you have there is a mixture of both. So, you
can get heat-wave resonances in this thing!

> I think this is really like a servo loop problem... we would like the
> feedback
> as fast as possible, then we can have higher gain without oscillation ???
> 
> So you want a package that is electrically isolated but an absolute
> excellent
> thermal conductor.

Um... that was not my intension...

> Answer (I have studied this a LOT lately...) Carbon...

Oh, what is it that you do which requires such measures?

> H^) harry  (see... I don't only geek you guys... I do this professionally
> too)

Count me in on that.... ;)

> BTW lets keep this going... If someone has a thermal inductor we COULD
> improve things a lot !!!

Certainly...

My angle was rather on improved methods for filtering heat
gradients. Think owen oscillators. I guess one has to rely on classic
heat transfer and spiff it up somehow...

Cheers,
Magnus