diy heatsinks - please give some advices - Page 3

Xoc1 · 19th November 2009, 10:29 PM

One point that you might consider is the different thermal conductivity of aluminium alloys.
The 1000 series aluminum is the purest, and has the highest thermal conductivity. 1050 for instance has a thermal conductivity of 222W/m.K
(and feels cold to touch)

5052 which is a grade that is used for some extrusions, because of it's harder wearing and corossion resistance properties is only 138w/m.K.

Technical info on the differing grades is available here
Aalco - Technical Info - Aluminium

StevenOH · 19th November 2009, 11:19 PM

Look at page 8 of this doc:
http://passdiy.com/pdf/PLH_amplifier.pdf
It will give an idea how to make an efficient heatsink.

DQ · 20th November 2009, 07:47 AM

Well, the dices have been thrown. I bought the L shaped aluminum profile for the teeth. Still waiting for your opinions on sanding (or not) the anodized contact surface of the teeth (the _ of the L).

Karsten Sømand · 20th November 2009, 08:59 AM

Hi DQ!

Just to understand you right. You are going to mount the L-profiles at a row on the side of your amplifier, yes?

New L-profiles are pretty precisely made from factory so there is a risk that you will "spoil" the surface when grinding it (by hand, at least). The most important thing is to avoid air between the side of the amp and the L-shape profiles. Even a tiny bit of air between two surfaces acts as an insulator.

If I were you I would use some thermal conductive sheet - or paste - between the profiles and the amp. But, maybe you can find some heat resistant glue which will not act as an insulator??? The solution with glue is only valid if you want a permanent solution and would like to avoid a lot of drillings, bolts and nuts!

BTW, maybe you could use a little (strong, 2-component) glue on the top and bottom of the the L-profiles and use some thermal conductor in between. This will be a good solution, I think, and will give a nice, clean look.

Let´s hear what you decide.

Karsten

DQ · 20th November 2009, 01:49 PM

Hi! Yes, you understood correctly. I will use some thermal paste indeed. Right now I'm in the middle of cutting actually, I only took a lunch break just having finished cutting half of the teeth. 24 down, 24 to go! As far as grinding is concerned, I know what you mean, I just find it hard to estimate which is the lesser evil: "spoiling" the surface, as you said, or allowing the heat transfer to be impeded somewhat by the oxide layer created through the anodizing process. Everybody please post your opinion on this - or maybe I should create a poll?

No glue, I will use screws in the end because 1. I expect to be able to clamp the L profile against the main sheet of aluminum (which will actually be the amplifier side, indeed) better this way and 2. I've just bought them yesterday

gfiandy · 20th November 2009, 02:02 PM

Leave the anodizing in place, an uneven surface will be much worse than a few microns of oxide. Several the heatsinks I have used in comerical designs have been anodised, I have never noticed any difference between anodised and unanodised ones in heat transfer. If you anodize black from silver you can see a small increase in the efficiency of the heat sink due to black body radiation.

Regards,
Andrew

trd1587 · 02:59 PM

Hi there, just my taught,

PC's had that problem of dissipating alot ot heat. Now they are using heat pipes for this Problem. The Pros are that it is very effective. The cons is that it uses alot of space. I immagine that the space in you projet has been determined. But if you look at some designs of CPU' and GPU \ Chipset coolers using the heat pipes you might wanna do the same with your project. Only with convection winds (no fan running), they do a very good job. Perhaps you could place the heat exchanger outside the casing? I'll join a link to a Model. Please note that they go for as cheap as 25$ Us. with some with alot of copper @ 100$.

ASUSTeK Computer Inc.

http://asus.com/product.aspx?P_ID=Xj...30d&templete=2

Comments appreciated.

Marc

tiefbassuebertr · 20th November 2009, 07:26 PM

Quote:

Originally Posted by trd1587

Hi there, just my taught,

PC's had that problem of dissipating alot ot heat. Now they are using heat pipes for this Problem. The Pros are that it is very effective. The cons is that it uses alot of space. I immagine that the space in you projet has been determined. But if you look at some designs of CPU' and GPU \ Chipset coolers using the heat pipes you might wanna do the same with your project. Only with convection winds (no fan running), they do a very good job. Perhaps you could place the heat exchanger outside the casing? I'll join a link to a Model. Please note that they go for as cheap as 25$ Us. with some with alot of copper @ 100$.

ASUSTeK Computer Inc.

ASUSTeK Computer Inc.

Comments appreciated.

Marc

perhaps this could be the ultimate heatsink solution. It is very interest to know for me, when already there are such solutions inside in audio power amplifiers.

widman · 20th November 2009, 07:54 PM

I have a Denon DRA-35 receiver built in the late 1980s that uses a heat pipe.

MJL21193 · 20th November 2009, 08:47 PM

The heatpipe idea in mobos is mainly to attract the buyer - it looks cool and sounds cool: "look at that, it's a heatpipe!!".
They are no more efficient than the standard cooler.

19th November 2009, 11:19 PM	#22
StevenOH diyAudio Member Join Date: Jun 2004 Location: USA	Look at page 8 of this doc: http://passdiy.com/pdf/PLH_amplifier.pdf It will give an idea how to make an efficient heatsink. __________________ The truth is out there. Who can handle the truth?

20th November 2009, 02:40 PM	#27
trd1587 diyAudio Member Join Date: Oct 2009 Location: Thurso, Quebec, Canada	You Might want to try tu use the PC developpement. Hi there, just my taught, PC's had that problem of dissipating alot ot heat. Now they are using heat pipes for this Problem. The Pros are that it is very effective. The cons is that it uses alot of space. I immagine that the space in you projet has been determined. But if you look at some designs of CPU' and GPU \ Chipset coolers using the heat pipes you might wanna do the same with your project. Only with convection winds (no fan running), they do a very good job. Perhaps you could place the heat exchanger outside the casing? I'll join a link to a Model. Please note that they go for as cheap as 25$ Us. with some with alot of copper @ 100$. ASUSTeK Computer Inc. http://asus.com/product.aspx?P_ID=Xj...30d&templete=2 Comments appreciated. Marc Last edited by trd1587; 20th November 2009 at 02:59 PM.

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19th November 2009, 10:29 PM	#21
Xoc1 diyAudio Member Join Date: Nov 2008 Location: Devon UK	One point that you might consider is the different thermal conductivity of aluminium alloys. The 1000 series aluminum is the purest, and has the highest thermal conductivity. 1050 for instance has a thermal conductivity of 222W/m.K (and feels cold to touch) 5052 which is a grade that is used for some extrusions, because of it's harder wearing and corossion resistance properties is only 138w/m.K. Technical info on the differing grades is available here Aalco - Technical Info - Aluminium

20th November 2009, 07:47 AM	#23
DQ diyAudio Member Join Date: Feb 2009	Well, the dices have been thrown. I bought the L shaped aluminum profile for the teeth. Still waiting for your opinions on sanding (or not) the anodized contact surface of the teeth (the _ of the L).

20th November 2009, 08:59 AM	#24
Karsten Sømand diyAudio Member Join Date: Mar 2006 Location: Outside Copenhagen	Hi DQ! Just to understand you right. You are going to mount the L-profiles at a row on the side of your amplifier, yes? New L-profiles are pretty precisely made from factory so there is a risk that you will "spoil" the surface when grinding it (by hand, at least). The most important thing is to avoid air between the side of the amp and the L-shape profiles. Even a tiny bit of air between two surfaces acts as an insulator. If I were you I would use some thermal conductive sheet - or paste - between the profiles and the amp. But, maybe you can find some heat resistant glue which will not act as an insulator??? The solution with glue is only valid if you want a permanent solution and would like to avoid a lot of drillings, bolts and nuts! BTW, maybe you could use a little (strong, 2-component) glue on the top and bottom of the the L-profiles and use some thermal conductor in between. This will be a good solution, I think, and will give a nice, clean look. Let´s hear what you decide. Karsten

20th November 2009, 01:49 PM	#25
DQ diyAudio Member Join Date: Feb 2009	Hi! Yes, you understood correctly. I will use some thermal paste indeed. Right now I'm in the middle of cutting actually, I only took a lunch break just having finished cutting half of the teeth. 24 down, 24 to go! As far as grinding is concerned, I know what you mean, I just find it hard to estimate which is the lesser evil: "spoiling" the surface, as you said, or allowing the heat transfer to be impeded somewhat by the oxide layer created through the anodizing process. Everybody please post your opinion on this - or maybe I should create a poll? No glue, I will use screws in the end because 1. I expect to be able to clamp the L profile against the main sheet of aluminum (which will actually be the amplifier side, indeed) better this way and 2. I've just bought them yesterday

20th November 2009, 02:02 PM	#26
gfiandy Audio Engineer diyAudio Member Join Date: Jul 2003 Location: Cambridge UK	Leave the anodizing in place, an uneven surface will be much worse than a few microns of oxide. Several the heatsinks I have used in comerical designs have been anodised, I have never noticed any difference between anodised and unanodised ones in heat transfer. If you anodize black from silver you can see a small increase in the efficiency of the heat sink due to black body radiation. Regards, Andrew

20th November 2009, 07:54 PM	#29
widman diyAudio Member Join Date: Feb 2004 Location: Deep Elem	I have a Denon DRA-35 receiver built in the late 1980s that uses a heat pipe.

20th November 2009, 08:47 PM	#30
MJL21193 Account disabled at member's request Join Date: Mar 2007	The heatpipe idea in mobos is mainly to attract the buyer - it looks cool and sounds cool: "look at that, it's a heatpipe!!". They are no more efficient than the standard cooler.

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