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Forum index » Science and Technology » Engineering » Mechanics
Liquid Heat Pipe Design, Orientation & Wicking Material
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wwswimming@yahoo.com
science forum beginner


Joined: 13 Sep 2005
Posts: 16

PostPosted: Thu Jun 22, 2006 2:59 pm    Post subject: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

i am looking for some Senior Technical Guidance from a physicist and/or
engineer and/or anybody that is knowledgeable about heat pipe design
.... or has taken a hack-saw to a high quality heat pipe.

here's some examples ... these heat sinks use heat pipes as part of the
thermal circuit from heat source to ambient air.

http://xbitlabs.com/articles/coolers/display/noctua-coolers_3.html

here's an excerpt from a previous post on the same subject, where i
talk about the orientation of the heat pipe. (below)

basically, the heat pipes for computer heat-sink-fan assemblies are
usually used in a horizontal configuration (the part that is attached
to the heat sink fins is horizontal, when the heat-sink-fan is used on
a computer in a tower case.)

the "dogma" among computer enthusiasts is that "it doesn't matter too
much", the orientation that is.

this puts some reliance on the "wick" inside the heat pipe, in order to
get the thermal resistance down to a target .14 degrees C per watt.

thinking about it from the point of view of making my own heat pipes,
it seems like the placement of a wicking geometry will make it more
difficult for the fluid inside the heat pipe to circulate.

any references to technical papers or web pages that go into more
detail on this subject would be most appreciated !

so far i found this. the reference to usage in satellites (no gravity,
no horizontal or vertical) is interesting.

http://www.heatsink-guide.com/heatpipes.shtml

RSVP

wwswimming
at
yahoo
dot com

- - -

i am writing to ask for your help making sure that i am using the
heat-pipe technology correctly.

in my work as an engineer, when we used the term "heat pipe" it was
always for any construction that acted as a conduit for heat energy,
from the heat source, to a surface closer to the "cold-plate".

now, with PC's, like this
http://xbitlabs.com/articles/coolers/display/noctua-coolers_3.html

Noctua heat sink, i believe that the heat pipes in it are filled with
some liquid. for example, ammonia, since it boils at a lower
temperature. this part is my imagination - the bubbles are lighter
than the surrounding liquid so they "go up". when they get to a cooler
part of the envelope to which they are restricted, they experience
another phase change back to liquid.

in each of those phase changes, from liquid to bubble and then from
bubble to liquid, there is a latent heat of evaporation & condensation
that is very effective in "moving heat".

OK but there's a big assumption in all of this - the ORIENTATION of the
heat sink.

i haven't taken apart the heatsinks like the Zalman and the Thermal
right and the Noctua. from the way they're pinched off, and from a lot
of the posts about them, i get the conclusion that they are liquid
filled and that the movement of the liquid inside the heatpipe
genuinely helps heat transfer, whether or not the liquid turns into
fizzy little bubbles in the process.

is the main part of this heat sink supposed to be vertical ?

this would mean that, when they are placed in a conventional tower
workstation, the end of the heat pipe away from the CPU, is horizontal.
so, how does the cooled-off fluid get returned to the CPU area of the
heat pipe for another dose of heat ? if the heat pipe is horizontal,
and it's a skinny heat pipe, it's not like pouring cold vodka into hot
chocolate, in which case it mixes real quick.

so i'm wondering, since most of us computer folks are using tower cases
of one kind or another, doesn't that leave these big beautiful heat
sinks operating in a sub-optimal orientation, with horizontal heat
pipes ?

have any of you experimented with your systems, like for example
measuring CPU temperatures with the case mounted horizontally and
vertically, to see if there's a difference ?

thanks for some good technical feedback. vodka-hot chocolate recipes
are appreciated too. Very Happy
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Ed Ruf
science forum beginner


Joined: 19 Jun 2005
Posts: 40

PostPosted: Thu Jun 22, 2006 3:27 pm    Post subject: Re: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

On 22 Jun 2006 07:59:43 -0700, in sci.engr.mech wwswimming@yahoo.com
wrote:


Quote:
any references to technical papers or web pages that go into more
detail on this subject would be most appreciated !
http://ntrs.nasa.gov/index.cgi?method=search&limit=25&offset=0&mode=simple&order=DESC&keywords=%22heat+pipe%22
Back to top
Brian Whatcott
science forum Guru Wannabe


Joined: 09 May 2005
Posts: 267

PostPosted: Thu Jun 22, 2006 5:19 pm    Post subject: Re: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

I will share what little I have on heat pipes.

In order to provide thermal conductivity better than solid copper, it
is necessary to operate a fluid near its change of state to gas from
liquid. Water can be used - reduced pressure provides a lower
operating point for temperature. A thin absorbant sheath at the inner
tube surface provides a liquid path, while the center provides a gas
path.

Brian Whatcott Altus OK

On 22 Jun 2006 07:59:43 -0700, wwswimming@yahoo.com wrote:

Quote:

i am looking for some Senior Technical Guidance from a physicist and/or
engineer and/or anybody that is knowledgeable about heat pipe design
... or has taken a hack-saw to a high quality heat pipe.

here's some examples ... these heat sinks use heat pipes as part of the
thermal circuit from heat source to ambient air.

http://xbitlabs.com/articles/coolers/display/noctua-coolers_3.html

here's an excerpt from a previous post on the same subject, where i
talk about the orientation of the heat pipe. (below)

basically, the heat pipes for computer heat-sink-fan assemblies are
usually used in a horizontal configuration (the part that is attached
to the heat sink fins is horizontal, when the heat-sink-fan is used on
a computer in a tower case.)

the "dogma" among computer enthusiasts is that "it doesn't matter too
much", the orientation that is.

this puts some reliance on the "wick" inside the heat pipe, in order to
get the thermal resistance down to a target .14 degrees C per watt.

thinking about it from the point of view of making my own heat pipes,
it seems like the placement of a wicking geometry will make it more
difficult for the fluid inside the heat pipe to circulate.

any references to technical papers or web pages that go into more
detail on this subject would be most appreciated !

so far i found this. the reference to usage in satellites (no gravity,
no horizontal or vertical) is interesting.

http://www.heatsink-guide.com/heatpipes.shtml

RSVP

wwswimming
at
yahoo
dot com

- - -

i am writing to ask for your help making sure that i am using the
heat-pipe technology correctly.

in my work as an engineer, when we used the term "heat pipe" it was
always for any construction that acted as a conduit for heat energy,
from the heat source, to a surface closer to the "cold-plate".

now, with PC's, like this
http://xbitlabs.com/articles/coolers/display/noctua-coolers_3.html

Noctua heat sink, i believe that the heat pipes in it are filled with
some liquid. for example, ammonia, since it boils at a lower
temperature. this part is my imagination - the bubbles are lighter
than the surrounding liquid so they "go up". when they get to a cooler
part of the envelope to which they are restricted, they experience
another phase change back to liquid.

in each of those phase changes, from liquid to bubble and then from
bubble to liquid, there is a latent heat of evaporation & condensation
that is very effective in "moving heat".

OK but there's a big assumption in all of this - the ORIENTATION of the
heat sink.

i haven't taken apart the heatsinks like the Zalman and the Thermal
right and the Noctua. from the way they're pinched off, and from a lot
of the posts about them, i get the conclusion that they are liquid
filled and that the movement of the liquid inside the heatpipe
genuinely helps heat transfer, whether or not the liquid turns into
fizzy little bubbles in the process.

is the main part of this heat sink supposed to be vertical ?

this would mean that, when they are placed in a conventional tower
workstation, the end of the heat pipe away from the CPU, is horizontal.
so, how does the cooled-off fluid get returned to the CPU area of the
heat pipe for another dose of heat ? if the heat pipe is horizontal,
and it's a skinny heat pipe, it's not like pouring cold vodka into hot
chocolate, in which case it mixes real quick.

so i'm wondering, since most of us computer folks are using tower cases
of one kind or another, doesn't that leave these big beautiful heat
sinks operating in a sub-optimal orientation, with horizontal heat
pipes ?

have any of you experimented with your systems, like for example
measuring CPU temperatures with the case mounted horizontally and
vertically, to see if there's a difference ?

thanks for some good technical feedback. vodka-hot chocolate recipes
are appreciated too. Very Happy
Back to top
Bret Cahill
science forum Guru


Joined: 05 May 2005
Posts: 480

PostPosted: Fri Jun 23, 2006 6:47 am    Post subject: Re: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

Micro heat pipes use surface tension to move the liquid phase in the
corners of the pipe.

They don't have a wick.


Bret Cahill
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Bernhard Kuemel
science forum beginner


Joined: 03 May 2005
Posts: 18

PostPosted: Sat Jun 24, 2006 7:14 pm    Post subject: Re: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

wwswimming@yahoo.com wrote:
Quote:
i am looking for some Senior Technical Guidance from a physicist and/or
engineer and/or anybody that is knowledgeable about heat pipe design
... or has taken a hack-saw to a high quality heat pipe.

I built a heat pipe that uses gravity to return the liquid for my intel
Celeron 733 MHz:

http://bksys.at/bernhard/vaporcooling/


Bernhard
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wwswimming@yahoo.com
science forum beginner


Joined: 13 Sep 2005
Posts: 16

PostPosted: Sun Jun 25, 2006 3:53 am    Post subject: Re: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

TOTALLY F*CKING COOL ! ! !

learn by doing.

did you do all the metal work yourself ?

regards,

WW


Bernhard Kuemel wrote:

Quote:
I built a heat pipe that uses gravity to return the liquid for my intel
Celeron 733 MHz:

http://bksys.at/bernhard/vaporcooling/


Bernhard
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Bernhard Kuemel
science forum beginner


Joined: 03 May 2005
Posts: 18

PostPosted: Sun Jun 25, 2006 1:45 pm    Post subject: Re: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

wwswimming@yahoo.com wrote:
Quote:
TOTALLY F*CKING COOL ! ! !

learn by doing.

And I learned about heat pipes only after I finished my work. That's why
I called it vapor cooling and not heat pipe.

Quote:
did you do all the metal work yourself ?

Yes, the sawing, drilling, grinding, polishing, glueing. I bought the
aluminium pipe and the copper bar. Ohh, and I also cast the aluminium
pieces that stopper the radiator pipe, using a piece of copper pipe as
mould.

Bernhard
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wwswimming@yahoo.com
science forum beginner


Joined: 13 Sep 2005
Posts: 16

PostPosted: Sat Jul 08, 2006 10:17 pm    Post subject: Re: Liquid Heat Pipe Design, Orientation & Wicking Material Reply with quote

well, if i lived in *.at - that's austria ? - i'd invite you
to come on over & have a brewski & melt some
metal.

i still have most of my tools but if i fire up my
kiln in the apartment i'm in now i have this idea
that i'd be waving goodbye to getting my
security deposit back.

i have some experience with investment casting
for lost wax & vacuum casting.

i'd like to set up a larger vacuum casting set-up
but not in a studio apartment !


Bernhard Kuemel wrote:
Quote:
wwswimming@yahoo.com wrote:
TOTALLY F*CKING COOL ! ! !

learn by doing.

And I learned about heat pipes only after I finished my work. That's why
I called it vapor cooling and not heat pipe.

did you do all the metal work yourself ?

Yes, the sawing, drilling, grinding, polishing, glueing. I bought the
aluminium pipe and the copper bar. Ohh, and I also cast the aluminium
pieces that stopper the radiator pipe, using a piece of copper pipe as
mould.

Bernhard
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