heat transfer through different mediums

[STEvil]

Where can I find numbers for:

Heat transfer rates through copper, air, water, aluminum, silver, and other mediums?

Copper to water, Copper to air, aluminum to water, and aluminum to air would all also be nice if someone can find them but not really required. Numbers showing the rate the heat transfers internally of the medium are most important.

Project B: 1%. ;)

[MaxxxRacer]

ooooh.. that would be interesting... no freeking clue.. lol.

[STEvil]

silver to water and silver to air.. those would be handy ;)

[MaxxxRacer]

would be a factor of like 2 or 3x for water over air i think. no numbers though

with the specific heat capacity of each material you can calculate it. im just not sure of the equation. I will look it up in google.. I would say i would look it up in my 200 dollar phsycis book, but it doesnt have more than 4 pages on thermodynamics.

[Nubius]

I believe diamonds are supposed to have a ridiculous heat dissipation qualities.....so yeah when I hit the lotto I'm getting a diamon cut CPU water block :D

[MaxxxRacer]

lol.. one problem man... there are no dimaonds that big... and the hope diamond (biggest in the world) costs serveral hundred million if i recal correctly.. so the lotto wouldnt even take care of the cost.. lol...

[STEvil]

Could possibly fabricate great big cubic zirconia... maybe i'll look into that later lol.

actually, thats quite funny.. we have some of the indications of diamond feilds around here (shallow spots, red clay, etc) and may have possibly found one already (low grade though if it is)... :D

[MaxxxRacer]

well there is this one lady (a chemist) who makes diamonds. she perfected a process to creat perfect flawless diamonds of various sizes.. im sure she could make one big enough for our needs. but who wants to pay like several hundred grand just for that.. lol... only thing is that all of her diamonds are colored. she does this so ppl cant sell them as the real thing, as they are entirely real in EVERY way and there is no differnce between these and the ones found in the ground.

[antipop]

I've some numbers after a thermodynamics class i took, i'll try to find them again and post them

edit : those are the numbers i have : it's the value of h the thermic transmission coefficient (i hope i have the right names as i don't know them in english)

Gases : natural convection : h = 5 to 30 W.m^(-2).K^(-1)
forced convection : h = 10 to 300 W.m^(-2).K^(-1)


Water : natural convection : h = 100 to 1000 W.m^(-2).K^(-1)
forced convection : h = 300 to 12000 W.m^(-2).K^(-1)

Oil : forced convection : h = 50 to 1700 W.m^(-2).K^(-1)

Liquid metal : forced convection : h = 6000 to 11000 W.m^(-2).K^(-1)

I hope those are the numbers who were looking for, forced convection are turbulent mouvement (which is why blocks have those design to make the water turbulent) and they allow better heat transfer
If you need any help with physics i can always take a look at some equation, it's been a while since i studied thermodynamics but a small freshening should do it ;)

[STEvil]

I think they are.. larger numbers means they move energy (heat) faster right?

Say I put two 30cm x 1cm x 1cm peices of aluminum and copper side by side, if I applied 100w to one end of both which one is going to heat up the opposite end faster?

Thats what i'm looking for... copper is faster at moving energy than aluminum IIRC, but aluminum can dissipate it faster. Silver was somewhere inbetween. I need numbers on each one though, "liquid metal" (as in melted?) is pretty generic, unless maybe they meant mercury?

maxxx - got any contact info on her? Maybe i'll try getting in contact with her just for fun :D

[antipop]

Larger is better ;) this is in the case of convection meaning a transfer between a liquid and a solid
The dissipated power is : phi = h * (Temp of solid - Temp of liquid)

As for your question i would say the copper will heat up the Al

[Ancient_1]

Thats what i'm looking for... copper is faster at moving energy than aluminum IIRC, but aluminum can dissipate it faster.
The heat transfer properties wont change no matter which direction you are going ie copper absorbs quicker but aluminum dissipates quicker is false. I think the reason this has come up is that in areas where cost isnt a factor but dissipating heat is you do see a fair amount of aluminum used, but it is usually used for a different reason weight.

For a given weight you can get better heat dissipation from aluminum than copper but with all things being equal copper will dissipate heat much quicker than aluminum.

[Butcher_]

Say I put two 30cm x 1cm x 1cm peices of aluminum and copper side by side, if I applied 100w to one end of both which one is going to heat up the opposite end faster?

Copper.
You're after the thermal conductivity.
Al 6063-T6 is 200W/m-K
Cu C110 is 388W/m-K
So copper has almost twice the conductivity of Al.
That in turn means it will convect heat better to water or air.

[saratoga]

Its easy for solids. Just look up the thermal conductivity.

For liquids or liquid solid systems, you're in the wrong place. Theres no simple way to calculate all but the most trivial heat transfer problems, and people who deal with this stuff (MEs, AEs, etc) spend years learning physics and models that attempt to explain how fluids behave in contact with a metal, etc.


Say I put two 30cm x 1cm x 1cm peices of aluminum and copper side by side, if I applied 100w to one end of both which one is going to heat up the opposite end faster?

Thats what i'm looking for... copper is faster at moving energy than aluminum IIRC, but aluminum can dissipate it faster. Silver was somewhere inbetween. I need numbers on each one though, "liquid metal" (as in melted?) is pretty generic, unless maybe they meant mercury?

No thats not right at all. For a solid, all that matters is thermal conductivity, so you can figure out which will move heat faster just by looking at the conductivity. Copper is clearly better, by almost a factor of 2. But if you want to do things more complicated, like calculate temperature gradiants, its a mess of partial differential equations and everything stops making sense :(

[antipop]

Its easy for solids. Just look up the thermal conductivity.

For liquids or liquid solid systems, you're in the wrong place. Theres no simple way to calculate all but the most trivial heat transfer problems, and people who deal with this stuff (MEs, AEs, etc) spend years learning physics and models that attempt to explain how fluids behave in contact with a metal, etc.

There's a lot of equation who allow you to have an idea, of course it's very simplistic and doesn't work in most cases (turbulent fluid is very complex and can refer to the chaos theory). Linear fluid are quite esay to study. From the heat exchange point of view, i think it's easier to compute

[MaxxxRacer]

anitpop, do you have any thermal transfer progs?? it would be cool to put one of our blocks cad files into the prog and do a simulation with the heat applied and watch the heat transfer through the water..

only problem would be the fact that the compuattion time would be in the months...

[antipop]

sorry Maxxxracer or should i say Royal Arse? :D I don't know how to use such a soft and i don't have one, all i've used is some thermodynamics equation on paper (triple integrals without a calculator is so much fun) maybe you could ask cathar, i'm pretty sure he has one of those soft and knows how to use them

[MaxxxRacer]

ROFL!!! tripple intergrals without a Ti-89... ur mad man. integration by parts, partial fractions, trig subsititution (god i hate trig with a pasion), regular substitution.. oh the fun of integrals.

[antipop]

ROFL!!! tripple intergrals without a Ti-89... ur mad man. integration by parts, partial fractions, trig subsititution (god i hate trig with a pasion), regular substitution.. oh the fun of integrals.
Yep i used to eat those and that was the easy part ;) All exams without a calculator, i still wonder why i bought the Ti-92 as i barely used it at least in math (believe doing some limited developpement by hand is really challenging)

[MaxxxRacer]

lol.. u must be good at integrals.. im just learning all thos rules.. not very good at it yet..

me, i girp my ti-89 like i am holding my heart in my chest.

[nebuchanezzar]

Thermal conductivity is :silver > copper > aluminum which I remember from high school as those are elements but I never reallylearned about anything with multiple elements like water for example.

The heat transfer properties wont change no matter which direction you are going ie copper absorbs quicker but aluminum dissipates quicker is false. I think the reason this has come up is that in areas where cost isnt a factor but dissipating heat is you do see a fair amount of aluminum used, but it is usually used for a different reason weight.
I work at an aluminum casting plant and besides weight the bigger reason is cost. Aluminum is pretty cheap compared to anything else. Being lighter if two hs were the same weight the aluminum one would have a lot more surface area for better dissapation of the heat. The biggest question I would think would have to involve waters heat absorbtion. Using distilled water helps to keep it relatively uniform but...pure water doesn't even conduct electricity...its all the ions from various metals and stuff in the water that does that. Just my 2 cents on it, but some #s in black and white would be pretty cool

[MaxxxRacer]

true water by itself is not conductive, but you have to have it in a special container to keep it from ionizing.. even exposing it to air will ionize it. also having it deinoized in a watercooling loop it is more of a solvent than normal and would do funny stuff to the cooling loop. (but this is on a very small scale as there isnt much water in the loop, but if you ran a constant stream of fresh deionzized water through the system it would cause problems over time)

[antipop]

true water by itself is not conductive, but you have to have it in a special container to keep it from ionizing.. even exposing it to air will ionize it. also having it deinoized in a watercooling loop it is more of a solvent than normal and would do funny stuff to the cooling loop. (but this is on a very small scale as there isnt much water in the loop, but if you ran a constant stream of fresh deionzized water through the system it would cause problems over time)
This is false, no matter how pure the water is, you'll still have a chemical reaction going on which H2O <=> H3O+ + OH-
The concentration of the ion is very small (10^(-14) ) but still existant

Maxxx, yeah i'm quite good at math in general and i had pretty advanced courses

[MaxxxRacer]

hmm.. well for all intesive purposes its rather non-conductive. with that kind of concentration im sure it has some capacitance but not entirely conductive

[antipop]

As i said it's very small but still existant, i doubt it would do any harm

[MaxxxRacer]

oh btw, what is the catalyst for the H20 to H30 + -H0.... is it just waters' natural tendency to ionize even when kept pure.

[saratoga]

This is false, no matter how pure the water is, you'll still have a chemical reaction going on which H2O <=> H3O+ + OH-
The concentration of the ion is very small (10^(-14) ) but still existant

Maxxx, yeah i'm quite good at math in general and i had pretty advanced courses

Does self ionization contribute to conductivity though? Seems like as soon as you setup a charge gradient you'd get recombination. I don't know enough to think about this correctly.

[MaxxxRacer]

saratoga, any ionization will make it more conductive. that was kind of his point.

[nebuchanezzar]

Didn't mean to get this going on the conductivity of water :) . Just impying that having an actual thermal conductivity would vary moreso with water than a metal waterblock or heatsink as those have pretty specific/exact amounts of x metal (97%copper and 3%zinc or something for example). Distilled water is the norm because de-ionized water does have a slighty -(?) ionic charge which is why it is able to absorb/bond with so many other things. I'm just of the opinion that in the quest to get the exchange of heat down that the water is the "larger" variable here. We of course all know that just for the density difference alone it is better than air and a water cooled system returns to idle temps faster than air(usually) but the original question was how well the heat transfers between x and water and x and air.

[MaxxxRacer]

oh thats easy.


its always higher with water... plain and simple.. water has a much higher heat capacity so it just transfer heat better..

[saratoga]

saratoga, any ionization will make it more conductive. that was kind of his point.

On more thought I think you are right. Seems like any EMF would push apart H+/OH-, leading to more ionization and more conduction, not less as I was thinking.

[MaxxxRacer]

oh lol.. i need to relearn my electronegativy values.. its cool that we are actually getting to use chemistry in this stuff. it makes it more fun.

btw, anitpop said it was H3O+ and OH-.. take two water molecles and thats what u get when u split them up. if you did it the way you are saying you would end up getting hydrogen gass spewing out from the water, which would be cool. but albeit incredibly dangerous.

EDIT: btw i know that hydrogen has is H2 and not just H...

[nebuchanezzar]

oh thats easy.


its always higher with water... plain and simple.. water has a much higher heat capacity so it just transfer heat better..

Yes but what I mean is someone can look up Cu..copper in a science book and it will list thermal conductivity, can we look up water also? It's been way too long since I was in school to be trying to rehash chemisty class :p:

sonething like this (http://www.bae.uky.edu/~snokes/BAE549thermo/physicalproperties/thermalprops.htm)

[MaxxxRacer]

oh.. lol.. google is your friend, confedon, dictionary, and encyclopedia

[MaxxxRacer]

its 4.184 joules per gram, where as Cu is .385... lol... only about 11 times the heat capacity.. no biggy

[nebuchanezzar]

its 4.184 joules per gram, where as Cu is .385... lol... only about 11 times the heat capacity.. no biggy

Isn't heat capacity how much it holds? I could be wrong but what is the heat transfer. For standing water I would assume its squat compared to moving water as an example jsut like a passive hs doesn't perform for squat compared to the same on w/a friggin tornado blowin thru it. I was under the impression that silver and then copper are the best conductors of heat but like I already said...it's been a long time since I tried to stay awake in school :D

[MaxxxRacer]

yah im trying to find some information on that. yes specific heat capacity is how much it holds. I would love to find some information on heat transmission rates though.

[saratoga]

oh lol.. i need to relearn my electronegativy values.. its cool that we are actually getting to use chemistry in this stuff. it makes it more fun.

btw, anitpop said it was H3O+ and OH-.. take two water molecles and thats what u get when u split them up. if you did it the way you are saying you would end up getting hydrogen gass spewing out from the water, which would be cool. but albeit incredibly dangerous.

EDIT: btw i know that hydrogen has is H2 and not just H...

Too long since I took AP chem, but as I recall, there are several models of how acid base reactions work. One of them uses Hydronium (H3O+) to hold the proton liberated by ionized water. It doesn't become H2 gas because theres no e- for it to combine with, at least not in pure water. Add an electric current to water and you will get H2 gas bubleing out.


Yes but what I mean is someone can look up Cu..copper in a science book and it will list thermal conductivity, can we look up water also? It's been way too long since I was in school to be trying to rehash chemisty class

You can but its very misleading. Conduction is only one of several ways heat moves through water. There are also various convective effects. I have no idea how to solve them, and from what I've seen of Bill, pH, Les and other's math, its not trivial and involves a lot of intuition backed by experimenting. Theres nothing trivial about fluid dynamics. People get their PHDs doing this kind of stuff.


Isn't heat capacity how much it holds?

Joules of heat held per gram of mass per degree. So temperature difference times specific heat times mass gives the energy in some volume of water. Obviously this is a good thing to have in a coolant since it will mean that each GPH of flow will carry a lot of energy. Lower it and you carry less heat.

Likewise it'll have no effect on solids like copper, because they have 0 flow and rely purely on conduction, which is not dependent on capacity, only conductivity.

[STEvil]

Copper.
You're after the thermal conductivity.
Al 6063-T6 is 200W/m-K
Cu C110 is 388W/m-K
So copper has almost twice the conductivity of Al.
That in turn means it will convect heat better to water or air.

exactly what i'm looking for, thanks!

All the rest of the stuff in this thread is gold too btw ;)

EDIT

Ahh... http://hyperphysics.phy-astr.gsu.edu/hbase/tables/thrcn.html
Water: http://www.lsbu.ac.uk/water/explan4.html
Conversion tools: http://www.processassociates.com/process/convert/cf_tcn.htm

[MaxxxRacer]

*steals thread and runs away screaming he has gold*

[nebuchanezzar]

*steals thread and runs away screaming he has gold*
Sneaks up for a drive by muggin :D

[antipop]

oh lol.. i need to relearn my electronegativy values.. its cool that we are actually getting to use chemistry in this stuff. it makes it more fun.

btw, anitpop said it was H3O+ and OH-.. take two water molecles and thats what u get when u split them up. if you did it the way you are saying you would end up getting hydrogen gass spewing out from the water, which would be cool. but albeit incredibly dangerous.

EDIT: btw i know that hydrogen has is H2 and not just H...
You're absolutely right my equation wasn't balanced ;)
The equation is 2H2O <=> H30+ + OH- (you have 4 H and 2 O on each side :) )
The way i described it is even cooler, you put one molecule of water and you end up getting twice the amount ;)

This reaction is always happening in the water (it happens in both directions until it reaches an equilibrium)
This is closely related to the pH, calcultated as the concentration of OH- in the water : pH = - log ([H3O+]).
Distilled water as a pH of 7 meaning that [H3O+] = 10^(-7) this is really a tiny amount!

ps : this is only true at 298K, you get more or less reaction as you rise or drop the temperature

[MaxxxRacer]

lol antipop... taking the log of a molecule... thats for next semester for me.

and 298K is relatively the temp that we work in so it applies to us.

[antipop]

lol antipop... taking the log of a molecule... thats for next semester for me.

and 298K is relatively the temp that we work in so it applies to us.
The log of a concentration isn't very hard to get is the concentration is 10^-3 the log will be 3 it's as simple as that (ok not so simple but you'll see)

ps : in what year are you?

[The Mofo]

You guys need to get out and hit some female a$$!!!

[Butcher_]

oh thats easy.

its always higher with water... plain and simple.. water has a much higher heat capacity so it just transfer heat better..
Mainly it's because water has much higher density and is a liquid.

[MaxxxRacer]

lol mofo.. who needs a$$ when u got a cd-rom drive.. just dont tell my gf that :p:

antipop, im second semester, first year.. just starting out. still in 2 dimensional space in physics. no accounting for friction either.

[antipop]

lol mofo.. who needs a$$ when u got a cd-rom drive.. just dont tell my gf that :p:

antipop, im second semester, first year.. just starting out. still in 2 dimensional space in physics. no accounting for friction either.
Then you still have a lot to learn :D You'll learn a not of useful stuff

Mofo, how much do you usualy pay ? :D :D :D :D

[Craig]

If still of interest Silver conductivity is 406 IIRC.

So the differnace between silver & copper is relativly small, at least as compared to the differance between copper or silver vs aluminum @ 205.