Graphene heat pipe...

[Clifford Heath]

On 9/12/20 9:35 am, John Larkin wrote:

On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

 

[John Larkin]

On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net>
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

 

[Clifford Heath]

On 9/12/20 11:55 am, John Larkin wrote:

On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

 

[Clifford Heath]

On 9/12/20 11:55 am, John Larkin wrote:

On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

 

[John Larkin]

On Wed, 9 Dec 2020 12:05:24 +1100, Clifford Heath <no.spam@please.net>
wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

OK, you don\'t design electronics.

 

[John Larkin]

On Wed, 9 Dec 2020 12:05:24 +1100, Clifford Heath <no.spam@please.net>
wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

OK, you don\'t design electronics.

 

[Clifford Heath]

On 9/12/20 12:19 pm, John Larkin wrote:

On Wed, 9 Dec 2020 12:05:24 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

OK, you don\'t design electronics.

You have a very fragile ego too. That makes me sad for you, because you
clearly know what you\'re doing, except where it comes to projecting your
personality.

Here\'s my work for this week, a HomeBus/WiFi thing with LCD. It uses
something like the gyrator I mentioned here a while back. Thanks to
those who helped. This is off to JLCPCB shortly.

<https://www.dropbox.com/preview/Public/powermon_3d_front.png>

CH

 

[Clifford Heath]

On 9/12/20 12:19 pm, John Larkin wrote:

On Wed, 9 Dec 2020 12:05:24 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that dissipates
about 3.5 times more heat than commercial copper heat pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

OK, you don\'t design electronics.

You have a very fragile ego too. That makes me sad for you, because you
clearly know what you\'re doing, except where it comes to projecting your
personality.

Here\'s my work for this week, a HomeBus/WiFi thing with LCD. It uses
something like the gyrator I mentioned here a while back. Thanks to
those who helped. This is off to JLCPCB shortly.

<https://www.dropbox.com/preview/Public/powermon_3d_front.png>

CH

 

[Liz Tuddenham]

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.


--
~ Liz Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk

 

[server]

On Wed, 9 Dec 2020 09:00:25 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.

A heat pipe connecting a CPU chip to a heat sink: 20 watts goes into
the hot end of the pipe, 20 watts comes out of the cold end; no
dissipation there. If the heat sink is 2 K/W, the sink dissipates 20
watts and rises 40C.

The delta-T in the heat pipe will be small, roughly 1 c, and its
surface dissipation small too.

Don\'t need a lot of thermodynamics to do that math.



--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Martin Brown]

On 09/12/2020 01:05, Clifford Heath wrote:

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

They are not all that far off the ideal behaviour though. An order of
magnitude better conductivity than a metal like copper or aluminium.

A vapour phase transition can move a lot of energy from the hot end to
the cool end and then wick back along the walls to repeat the cycle.

Graphene heat pipe only real advantage is lighter weight and \"coolness\".
(as in novelty value - horrendously expensive for what it is)

There is a tendency for graphene with everything at the moment.

--
Regards,
Martin Brown

 

[Liz Tuddenham]

<jlarkin@highlandsniptechnology.com> wrote:

On Wed, 9 Dec 2020 09:00:25 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what
dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.

A heat pipe connecting a CPU chip to a heat sink: 20 watts goes into
the hot end of the pipe, 20 watts comes out of the cold end; no
dissipation there. If the heat sink is 2 K/W, the sink dissipates 20
watts and rises 40C.

The delta-T in the heat pipe will be small, roughly 1 c, and its
surface dissipation small too.

Don\'t need a lot of thermodynamics to do that math.

Actually you don\'t even need maths; common sense and a knowledge of the
meaning of ordinary English words (or the ability to read a dictionary)
is sufficient.

Supposing I wanted to use a heat pipe to heat a cup of tea by dipping
one end in the cup and heating the other end (gently!) with a blowlamp -
would that be dissipation? Of course not.


--
~ Liz Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk

 

[Phil Hobbs]

On 12/9/20 11:26 AM, Martin Brown wrote:

On 09/12/2020 01:05, Clifford Heath wrote:

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

They are not all that far off the ideal behaviour though. An order of
magnitude better conductivity than a metal like copper or aluminium.

A vapour phase transition can move a lot of energy from the hot end to
the cool end and then wick back along the walls to repeat the cycle.

Graphene heat pipe only real advantage is lighter weight and \"coolness\".
(as in novelty value - horrendously expensive for what it is)

There is a tendency for graphene with everything at the moment.

Its other advantage is fragility (from the makers\' perspective). It
don\'t dent or bend so good.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Wed, 9 Dec 2020 16:24:17 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

jlarkin@highlandsniptechnology.com> wrote:

On Wed, 9 Dec 2020 09:00:25 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what
dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.

A heat pipe connecting a CPU chip to a heat sink: 20 watts goes into
the hot end of the pipe, 20 watts comes out of the cold end; no
dissipation there. If the heat sink is 2 K/W, the sink dissipates 20
watts and rises 40C.

The delta-T in the heat pipe will be small, roughly 1 c, and its
surface dissipation small too.

Don\'t need a lot of thermodynamics to do that math.

Actually you don\'t even need maths; common sense and a knowledge of the
meaning of ordinary English words (or the ability to read a dictionary)
is sufficient.

Well, you at least need some arithmetic to estimate how hot the chip
will get. You need to buy the right heat sink, and maybe fans.

There is an interesting quantitative analogy between thermals and
electricals:

ELECTRICAL THERMAL

1 amp 1 watt
1 farad 1 gram aluminum
1 volt 1 degree C
1 second 1 second
1 ohm 1 K/watt

which is accurate to about 10%. So you can use Spice to analyze either
static or transient thermal systems.

Supposing I wanted to use a heat pipe to heat a cup of tea by dipping
one end in the cup and heating the other end (gently!) with a blowlamp -
would that be dissipation? Of course not.

Not according to my use of the word.

I like to bench test things as a sanity check.

https://www.dropbox.com/sh/lzgr5422f49fvna/AAAi46OcivT97nIucu6JVl79a?dl=0



--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[server]

On Wed, 9 Dec 2020 11:44:11 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/9/20 11:26 AM, Martin Brown wrote:
On 09/12/2020 01:05, Clifford Heath wrote:

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

They are not all that far off the ideal behaviour though. An order of
magnitude better conductivity than a metal like copper or aluminium.

A vapour phase transition can move a lot of energy from the hot end to
the cool end and then wick back along the walls to repeat the cycle.

Graphene heat pipe only real advantage is lighter weight and \"coolness\".
(as in novelty value - horrendously expensive for what it is)

There is a tendency for graphene with everything at the moment.

There are material fads in academia.

Its other advantage is fragility (from the makers\' perspective). It
don\'t dent or bend so good.

Cheers

Phil Hobbs

They used to corrode internally and fail. Are they better now?



--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Phil Hobbs]

On 12/9/20 12:18 PM, jlarkin@highlandsniptechnology.com wrote:

On Wed, 9 Dec 2020 11:44:11 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/9/20 11:26 AM, Martin Brown wrote:
On 09/12/2020 01:05, Clifford Heath wrote:

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

They are not all that far off the ideal behaviour though. An order of
magnitude better conductivity than a metal like copper or aluminium.

A vapour phase transition can move a lot of energy from the hot end to
the cool end and then wick back along the walls to repeat the cycle.

Graphene heat pipe only real advantage is lighter weight and \"coolness\".
(as in novelty value - horrendously expensive for what it is)

There is a tendency for graphene with everything at the moment.

There are material fads in academia.




Its other advantage is fragility (from the makers\' perspective). It
don\'t dent or bend so good.

They used to corrode internally and fail. Are they better now?

They\'re used in the heatsinks of most of the servers in the world AFAIK.
I\'ve had six of them running in Supermicro boxes for a decade or so;
one running 24/7.

Copper and distilled water is a generally benign combination, and of
course you can use Prestone if you want oxidation inhibitor. Aluminum
may not be so good.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 12/9/20 12:04 PM, jlarkin@highlandsniptechnology.com wrote:

On Wed, 9 Dec 2020 16:24:17 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

jlarkin@highlandsniptechnology.com> wrote:

On Wed, 9 Dec 2020 09:00:25 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what
dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.

A heat pipe connecting a CPU chip to a heat sink: 20 watts goes into
the hot end of the pipe, 20 watts comes out of the cold end; no
dissipation there. If the heat sink is 2 K/W, the sink dissipates 20
watts and rises 40C.

The delta-T in the heat pipe will be small, roughly 1 c, and its
surface dissipation small too.

Don\'t need a lot of thermodynamics to do that math.

Actually you don\'t even need maths; common sense and a knowledge of the
meaning of ordinary English words (or the ability to read a dictionary)
is sufficient.


Well, you at least need some arithmetic to estimate how hot the chip
will get. You need to buy the right heat sink, and maybe fans.

There is an interesting quantitative analogy between thermals and
electricals:

ELECTRICAL THERMAL

1 amp 1 watt
1 farad 1 gram aluminum
1 volt 1 degree C
1 second 1 second
1 ohm 1 K/watt

which is accurate to about 10%. So you can use Spice to analyze either
static or transient thermal systems.


Supposing I wanted to use a heat pipe to heat a cup of tea by dipping
one end in the cup and heating the other end (gently!) with a blowlamp -
would that be dissipation? Of course not.

Not according to my use of the word.

I like to bench test things as a sanity check.

https://www.dropbox.com/sh/lzgr5422f49fvna/AAAi46OcivT97nIucu6JVl79a?dl=0

Sanity-checking the lunatic fringe. Tinfoil hats recommended.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 12/9/20 12:04 PM, jlarkin@highlandsniptechnology.com wrote:

On Wed, 9 Dec 2020 16:24:17 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

jlarkin@highlandsniptechnology.com> wrote:

On Wed, 9 Dec 2020 09:00:25 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what
dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.

A heat pipe connecting a CPU chip to a heat sink: 20 watts goes into
the hot end of the pipe, 20 watts comes out of the cold end; no
dissipation there. If the heat sink is 2 K/W, the sink dissipates 20
watts and rises 40C.

The delta-T in the heat pipe will be small, roughly 1 c, and its
surface dissipation small too.

Don\'t need a lot of thermodynamics to do that math.

Actually you don\'t even need maths; common sense and a knowledge of the
meaning of ordinary English words (or the ability to read a dictionary)
is sufficient.


Well, you at least need some arithmetic to estimate how hot the chip
will get. You need to buy the right heat sink, and maybe fans.

There is an interesting quantitative analogy between thermals and
electricals:

ELECTRICAL THERMAL

1 amp 1 watt
1 farad 1 gram aluminum
1 volt 1 degree C
1 second 1 second
1 ohm 1 K/watt

which is accurate to about 10%.

Fun, and potentially useful. Mind if I put it in my revised thermal
chapter?

So you can use Spice to analyze either
> static or transient thermal systems.
At least in situations where diffusion isn\'t important. When diffusion
matters, you get an extra 45 degrees\' phase shift every time your
amplitude goes down by 1/e, without limit. Using PID control in a
diffusion-dominated problem is not a growth strategy.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Wed, 9 Dec 2020 12:45:54 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/9/20 12:04 PM, jlarkin@highlandsniptechnology.com wrote:
On Wed, 9 Dec 2020 16:24:17 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

jlarkin@highlandsniptechnology.com> wrote:

On Wed, 9 Dec 2020 09:00:25 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what
dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.

A heat pipe connecting a CPU chip to a heat sink: 20 watts goes into
the hot end of the pipe, 20 watts comes out of the cold end; no
dissipation there. If the heat sink is 2 K/W, the sink dissipates 20
watts and rises 40C.

The delta-T in the heat pipe will be small, roughly 1 c, and its
surface dissipation small too.

Don\'t need a lot of thermodynamics to do that math.

Actually you don\'t even need maths; common sense and a knowledge of the
meaning of ordinary English words (or the ability to read a dictionary)
is sufficient.


Well, you at least need some arithmetic to estimate how hot the chip
will get. You need to buy the right heat sink, and maybe fans.

There is an interesting quantitative analogy between thermals and
electricals:

ELECTRICAL THERMAL

1 amp 1 watt
1 farad 1 gram aluminum
1 volt 1 degree C
1 second 1 second
1 ohm 1 K/watt

which is accurate to about 10%.

Fun, and potentially useful. Mind if I put it in my revised thermal
chapter?

No, please do. I think it\'s about right. Of course, thermal systems
are seldom so polite as to be made of lumped elements.

I haven\'t had time to review your draft. I\'ve been crushed, and
fatigued from what was probably The Virus. I\'ll try.

So you can use Spice to analyze either
static or transient thermal systems.
At least in situations where diffusion isn\'t important. When diffusion
matters, you get an extra 45 degrees\' phase shift every time your
amplitude goes down by 1/e, without limit. Using PID control in a
diffusion-dominated problem is not a growth strategy.

A string of R-Cs sorta works some times. Or an LTL.

In lieu of buying and learning serious software, I bench test. Do some
machining and get away from mice and screens for a while.





--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Phil Hobbs]

On 12/9/20 1:05 PM, jlarkin@highlandsniptechnology.com wrote:

On Wed, 9 Dec 2020 12:45:54 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/9/20 12:04 PM, jlarkin@highlandsniptechnology.com wrote:
On Wed, 9 Dec 2020 16:24:17 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

jlarkin@highlandsniptechnology.com> wrote:

On Wed, 9 Dec 2020 09:00:25 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Clifford Heath <no.spam@please.net> wrote:

On 9/12/20 11:55 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:57:19 +1100, Clifford Heath <no.spam@please.net
wrote:

On 9/12/20 9:35 am, John Larkin wrote:
On Wed, 9 Dec 2020 09:10:55 +1100, Clifford Heath <no.spam@please.net
wrote:

On 8/12/20 10:18 pm, Liz Tuddenham wrote:
Carl <carl.ijamesXYZ@ZYXverizon.net> wrote:

Researchers have constructed a heat pipe made from graphene that
dissipates about 3.5 times more heat than commercial copper heat
pipes.

Does it actually claim to dissipate heat? I thought heat pipes just
conducted heat to be dissipated elsewhere.

The rules of thermodynamics don\'t allow heat to be conducted elsewhere
without dissipating it.

What happens if I carry a thermos of hot coffee upstairs? Does that
create dissipation?

Heat pipes transport heated mass.

There has to be a thermal gradient or there\'s no
conduction, and that\'s what dissipation is.

Transportation doesn\'t need a gradient. It can work against a
gradient.

A heat pump requires dissipation elsewhere.

All thermal flow requires dissipation, because that\'s what
dissipation is.

We live in different worlds. I design electronic things with parts
that need to be cooled, and I need to get rid of the heat.

What do you do?

I try to avoid prevarication, which seems to be your #1 pastime.
I also use words that have meanings other people recognise, instead of
my private meanings.

Your tar truck and your carrying coffee upstairs are both examples of
heat pumps. The graphene heat pipe is passive, not a pump. Your heat
pump examples are pure prevarication, nothing more. We weren\'t talking
about heat pumps, and you tried to change the subject... your favorite
thing to do when you discover you\'re wrong.

If the passive pipe works, it dissipates heat. Perhaps the heat it
dissipates is transported to something that dissipates it further, but
heat pipes do not \"just\" conduct heat to be dissipated elsewhere.
Thermodynamics doesn\'t allow that.

DISSIPATION n Scattering, dispersion, disintegration; wasteful
expenditure of;... [The Concise Oxford Dictionary of Current English]

Heat energy flowing through a channel is conducted or transported by the
channel. Heat energy coming out of the end of a channel and flowing to
waste would be dissipated by the act of flowing to waste.
Alternatively, the energy could be collected in an area of lower energy
or used to do physical work; it would still flow through the channel but
there would be no dissipation.

The channel is not dissipating heat energy, the dissipation, if any,
takes place after the energy has left the channel.

A heat pipe connecting a CPU chip to a heat sink: 20 watts goes into
the hot end of the pipe, 20 watts comes out of the cold end; no
dissipation there. If the heat sink is 2 K/W, the sink dissipates 20
watts and rises 40C.

The delta-T in the heat pipe will be small, roughly 1 c, and its
surface dissipation small too.

Don\'t need a lot of thermodynamics to do that math.

Actually you don\'t even need maths; common sense and a knowledge of the
meaning of ordinary English words (or the ability to read a dictionary)
is sufficient.


Well, you at least need some arithmetic to estimate how hot the chip
will get. You need to buy the right heat sink, and maybe fans.

There is an interesting quantitative analogy between thermals and
electricals:

ELECTRICAL THERMAL

1 amp 1 watt
1 farad 1 gram aluminum
1 volt 1 degree C
1 second 1 second
1 ohm 1 K/watt

which is accurate to about 10%.

Fun, and potentially useful. Mind if I put it in my revised thermal
chapter?

No, please do. I think it\'s about right. Of course, thermal systems
are seldom so polite as to be made of lumped elements.

Thanks. I\'ll check before I do, obviously.

I haven\'t had time to review your draft. I\'ve been crushed, and
fatigued from what was probably The Virus. I\'ll try.

Sure, no worries. Hope you feel better soon. The book will be in
production for some months, and I can fix mistakes up till the fourth
printing, so Christmas isn\'t really a drop-dead date.

So you can use Spice to analyze either
static or transient thermal systems.
At least in situations where diffusion isn\'t important. When diffusion
matters, you get an extra 45 degrees\' phase shift every time your
amplitude goes down by 1/e, without limit. Using PID control in a
diffusion-dominated problem is not a growth strategy.

A string of R-Cs sorta works some times. Or an LTL.

In lieu of buying and learning serious software, I bench test. Do some
machining and get away from mice and screens for a while.

Yup. Uber-fancy simulation software is a full-time job to keep up with.
That\'s mostly what keeps me away from Comsol or LightTrans or those
sorts of things.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com