| Topic: |
Science > Physics |
| User: |
"asdf" |
| Date: |
04 May 2007 03:10:19 PM |
| Object: |
heat question ? |
Do materials exist that allow heat to move through them but not go
back the other way ?
Or does this go against the laws of physics ?
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| User: "CWatters" |
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| Title: Re: heat question ? |
04 May 2007 03:53:35 PM |
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"asdf" <qjohnny2000@yahoo.com> wrote in message
news:1178309419.094143.225570@y5g2000hsa.googlegroups.com...
Do materials exist that allow heat to move through them but not go
back the other way ?
Or does this go against the laws of physics ?
http://www.trnmag.com/Stories/2002/061202/One-way_heat_valve_possible_061202.html
http://focus.aps.org/story/v9/st11
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| User: "Andy Resnick" |
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| Title: Re: heat question ? |
07 May 2007 08:43:12 AM |
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CWatters wrote:
"asdf" <qjohnny2000@yahoo.com> wrote in message
news:1178309419.094143.225570@y5g2000hsa.googlegroups.com...
Do materials exist that allow heat to move through them but not go
back the other way ?
Or does this go against the laws of physics ?
http://www.trnmag.com/Stories/2002/061202/One-way_heat_valve_possible_061202.html
http://focus.aps.org/story/v9/st11
Interesting articles, especially the PRL. Do the researchers really
mean enthalpy or free energy, or do they refer to the entropic use of
'heat'? It seems they mean enthalpy (phonons etc.).
Interesting...
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
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| User: "PD" |
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| Title: Re: heat question ? |
05 May 2007 10:59:21 AM |
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On May 4, 3:53 pm, "CWatters"
<colin.watt...@turnersNOSPAMoak.plus.com> wrote:
"asdf" <qjohnny2...@yahoo.com> wrote in message
news:1178309419.094143.225570@y5g2000hsa.googlegroups.com...
Do materials exist that allow heat to move through them but not go
back the other way ?
Or does this go against the laws of physics ?
http://www.trnmag.com/Stories/2002/061202/One-way_heat_valve_possible...
http://focus.aps.org/story/v9/st11
Interesting. What occurred to me was a material that dispersed heat
through an irreversible process, like ablation. Heat source -> Inner,
nonablative material -> Outer, ablative material.
This would conduct more heat outward than inward, I think.
PD
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| User: "Eric Gisse" |
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| Title: Re: heat question ? |
04 May 2007 04:20:41 PM |
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On May 4, 1:10 pm, asdf <qjohnny2...@yahoo.com> wrote:
Do materials exist that allow heat to move through them but not go
back the other way ?
Or does this go against the laws of physics ?
A heat diode?
I don't see why not.
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| User: "Uncle Al" |
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| Title: Re: heat question ? |
04 May 2007 07:07:51 PM |
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Eric Gisse wrote:
On May 4, 1:10 pm, asdf <qjohnny2...@yahoo.com> wrote:
Do materials exist that allow heat to move through them but not go
back the other way ?
Or does this go against the laws of physics ?
A heat diode?
I don't see why not.
How's Maxwell's Demon for a start? Microscopic heat conduction
direction anisotropies have been realized. They don't scale.
Consider a Peltier element. It conducts electricty with low
resistance (small electron scattering) and it conducts heat with high
resistance (strong phonon scattering). If we did some fancy dancing
with heat and electricity conversion on either side... the First and
Second laws would not be in danger. "8^>)
One could use a supercon near Tc. Below Tc it is a superb thermal
insulator and an electrical supercon. Above Tc it is normal for heat
and current. There is still no way to cyclicly break thermodynamics.
Let's do it optically! Cold mirror - transmits visible light coming
inward but reflects IR that would otherwise be coming outward. Shine
light in OK, no heat exits. Would a cold mirror placed over a black
cavity do the dirty?
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2
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