[Stoves] Heat-pipes/thermal-diodes

nari phaltan nariphaltan at gmail.com
Wed Jan 29 22:43:25 CST 2014


Hello stovers,

Let me share with you some historical perspective on heat pipes. These
devices were developed during the hay days of NASA program for delivering
large amounts of heat from one place to another in a constrictive space.
Hence they used fluids which changed phase either in atmospheric pressure
or any other pressure inside the pipe. Generally they had a wick which
allowed suction fluid from one end to another.

This principle is being again looked very carefully in a constricted space
of IC chips in computers where huge amount of heat/unit area has to be
transferred for cooling purposes.

Our janta cooker used in the
lanstove<http://www.nariphaltan.org/kerolanstove.pdf> also
works on heat pipe principle.

In late 1970s we developed a solar oven in our lab at University of Florida
which used vegetable oils as heat transfer and storage medium from
concentrated solar collectors to the oven. The device worked well but
because of the breakdown of oils at high temperatures we had to change them
very often. We tried various inert atmospheres like nitrogen and CO2 gases
but were not successful. Since it was an M.tech project so after the
project finished it was not taken up later on.

Cheers.

Anil



On Thu, Jan 30, 2014 at 9:49 AM, CPP GMail <crispinpigott at gmail.com> wrote:

> Dear Ron
>
> I am wondering if the term 'heat pipe' is being used correctly here. I
> certainly know what a heat pipe is but the vacuum tube collectors used in
> these solar installations are not heat pipes. They are what is described in
> the text.
>
> They are vacuum insulated collectors being used in thermosiphon systems.
> The Mercedes cookers used a second thermosiphon to transfer heat from the
> main tank. That was not a heat pipe either though using a different working
> fluid it certainly could have and it might have solved the heat transfer
> rate problem.
>
> In my view that combination might be the best way to get solar cookers
> much more widely used, tackling the institutional market first. It allows
> the heart be collected any time, and the cooking to be done later. The heat
> pipe is the correct technology to draw the heat to the cooking vessel or
> surface. By varying the pressure in the tube the heat transfer rate can be
> controlled.
>
> Regards
> Crispin
>
> PS re the firewalled papers: you can write to the author and ask for a
> copy and they usually send it.
>
> ------------------------------
>
>
> Crispin and list:
>
>     Thanks for the updated cite.  Makes at least two that are not behind
> paywalls.  Hope we can find some that are even more current and easy
> obtainable.  But there is a big literature on heat pipes outside the
> cooking arena.
>
> I think we can learn a lot from the solar cooker side - but my interest is
> on biomass stoves and the ability to feed multiple pots from a single
> flame.  You talk also about thermo-siphoning and pumps.  I am describing
> neither of those - a heat pipe operates on a very different principle as I
> know you know.
>
> The word “diode” is important here.
>
> I talked with one of the last references in your cite - Mr.  C J Swet at
> about the time he wrote that 1974 article - on (I recall) a thermo siphon
> principle.
>
> Ron
>
>
>
>
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-- 
Nimbkar Agricultural Research Institute (NARI)
Tambmal, Phaltan-Lonand Road
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           nariphaltan at nariphaltan.org

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