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Old 10th October 2011, 01:48 AM   #31
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Location: Vermont
I agree with Mr. Wesley in regards to some of the comments. Perhaps it would be good to remove some of the pieces between the active device and the heatsink itself.

But I have been looking at this a bit differently. I personally wouldn't use water, due to the way electricity behaves when exposed to water. I would think that some oils would work well here. And no one has mentioned the best thing in regards to liquid cooling, if you have the liquid circulating out of the room entirely, you can have any fans, pumps, etc. located there, thus removing the noise factor.

I don't know any specifics, but I do recall talking with a friend at work about oils used for cooling that will use the heat to circulate passively, thus negating the need for a pump. Use the correct size heatsinks (one to absorb, one to radiate) and the proper layout of your plumbing, and then you have no need for fans or pumps!

Peace,

Dave
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Old 10th October 2011, 01:56 AM   #32
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A little bit here:

A unique cooling application for you guys... - AnandTech Forums
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Old 11th October 2011, 07:59 AM   #33
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I am not even going to go into replying to bitter comments.

I do however wish to point out a few things which have been overlooked.

1. Thermal contact. As you may now a contact surface degrades thermal transfer. One can do as much as possibile to avoid this degradation but at the end of the day it is there. In TEC cooling one of the best ways to ensure excellent thermal traansfer is to apply a great deal of pressure during clamping. This thins out the thermal paste (or equivalent material) and ensures the loss is to a minimum. I have personally seen polished surfaces (metal surfaces) create an airight seal with no thermal paste whatsoever. Obviously we need thermal paste so it is imperative that we thin the material out as much as possibile.

2. In order to ensure adequate clamping and avoid deformity in clamped surfaces (yes...even a 3mm plate of alumium will be deformed by uneven pressure) the pressure must be adequately distributed along the surface (wich for strips of output devices can be very lon indeed).

4. If we avoid aluminum convection cooling all together then we are left with a single cooling extrusion. Fine by me. Adequate clamping is paramount! Infact my initial design was oriented towards ensuring that level of pressure. Simply sticking the devices with some tape on the cooling extrusion simply won't do. That is why there is a reason if visual aids like renderisations are useful. Just imagine what would happen if uneven clamping caused a signifcant temperature differential.

Plus the to247 packaging does provide a single thermally efficient surface, not 2 or 3 or 4. Plastic is NOT a good conductor of heat. One could...and this came up from someone in this thread, have the clamping plate OVER the devices ensuring direct contact between the thermal pads and the cooling extrusion.

In regards to oil...I have tried it actually. The viscosity requires enormous pumps which generate noise, heat and require a lot of power. I also tried dipping the rads in mineral oil but it turned out to be a messy business with little advantage over fans. However if you have the time and means please experiment. I have done little research in this actually.

As far as water and electricyt go well....computers are delicate and often far more expensive than DIY builds. I guess it comes down to psychology. If you can accept that your amps are watercooled then just trust your workmanship and be happy
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Old 11th October 2011, 08:03 AM   #34
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Quote:
Originally Posted by dave_gerecke View Post
I agree with Mr. Wesley in regards to some of the comments. Perhaps it would be good to remove some of the pieces between the active device and the heatsink itself.

But I have been looking at this a bit differently. I personally wouldn't use water, due to the way electricity behaves when exposed to water. I would think that some oils would work well here. And no one has mentioned the best thing in regards to liquid cooling, if you have the liquid circulating out of the room entirely, you can have any fans, pumps, etc. located there, thus removing the noise factor.

I don't know any specifics, but I do recall talking with a friend at work about oils used for cooling that will use the heat to circulate passively, thus negating the need for a pump. Use the correct size heatsinks (one to absorb, one to radiate) and the proper layout of your plumbing, and then you have no need for fans or pumps!

Peace,

Dave
Yep that is very cool....actually it is called thermosiphon effect and can be basically achieved with any medium...heat reduces density and causes circulation witihin the system. I only fear that 500w+ of heat is just too much and would require enourmous radiators. Plus all the components must be spaced correctly. The rad must always be higher than the blocks and the water should have easy access to the rad once it has reached a sufficient temeperature. It can be done. Someone on xtremesystems did it. He couldn't go beyond stock CPU clocks as I recall and even then temperatures weren't that great. But as I said...if someone wishes to experiment please do so. And post your results. I am going to go with 6v pumps and 6v fans.Independent voltage control for both. I should be able to strike a balance between fan noise and pump noise by adjusting the two.
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Old 11th October 2011, 09:45 AM   #35
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you could actually go for an external device such as this:

Click the image to open in full size.

but pump power (head and flow) and cooling capacity are limited. Could work for small amps such as a couple of Hiragas at full power but I do not believe these could be used for something in the range of the aleph 5 - 1.2
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Old 11th October 2011, 09:47 AM   #36
AndrewT is offline AndrewT  Scotland
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Try to imagine an early automobile that had a vertical radiator and an engine that needed cooling without a water pump.

Simply standing the radiator next to the upright heat generator gives the thermo-syphon effect. Use large diameter pipe to connect top to top and bottom to bottom.

BTW,
a radiator works more effectively if it is connected Top and Bottom @ Opposite Ends (TBOE). Technically, the heat generator should also be connected TBOE, but this option is not usually available.

Pic in post35 shows BBOE for the radiator. This forces one to abandon thermosyphon and enforced use of a pump.
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regards Andrew T.

Last edited by AndrewT; 11th October 2011 at 09:55 AM.
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Old 11th October 2011, 10:20 AM   #37
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I believe thermosyphon can only provide a very limite amount of cooling. Once the system is in equilibrium the rad will have to exchange a great deal of heat which is something I think cannot be achieved without using powerful fans.

A small pump I think is required...it could be downvolted and insulated but some kind of forced flow must be achieved. Probably given the design of the "waterblock" flowrate is more important than head pressure making it so a pondpump would be able to accomplish the task.
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Old 13th October 2011, 07:46 PM   #38
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found it!

I had almost lost hope of finding an adequate radiator but here it is: designed ofr passive cooling.

Click the image to open in full size.

imagine 2 of these upright on an allumium base. Within the structure a plexi encasing and within 2 modules each with its own cooling extrusion on the botom level.

Two tubes per module will ensure warm water rises and cold descends from the top (50cm fall) to the cooler. No fans just plain air. All cicuitry will be encased within a plexi container on the bottom level and an allumium base will provide grounding plane for all devices.

Hopefull I will have a model by tomorrow. Very excited to try this! IT might actually turn out to be pleasing to eye too!

here you go AndrewT...and dave_gerecke.... I will follow your suggestions after all.
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Old 13th October 2011, 08:20 PM   #39
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here:

it goes without saying that the proportions are completely off...it should be much smaller and compact in reality.

Click the image to open in full size.
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Old 14th October 2011, 12:58 AM   #40
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Hello Alex, thermosiphoning was just one thought I had. I like the idea of less moving parts. It means less to fail, and less noise!

From my perspective, the biggest advantage of liquid cooling for your amps would be if you were to use fans/pumps you could place them in a different location than the listening room, thus removing the noise factor. The other advantage here being that if you live in a warmer climate, you are pulling the heat of the amps out of the area where humans are, thus also more comfortable.

I won't claim to be an expert, but I have some experience with liquid cooling. Both of my most recent employer and previous one used liquid cooling. The first one was using it to cool active devices on PCB's in a high volume tester for semiconductors. We used HFE-7100 there. They didn't like the idea of water around electricity for some reason, and Flourinert was crazy expensive (as was observed earlier).

Peace,

Dave

Last edited by dave_gerecke; 14th October 2011 at 12:59 AM. Reason: typo
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