[Amps] Solid state amplifier cooling

[Fuqua, Bill L]

  I noticed just now someone suggested water cooling. 
The advantage of doing it this way is that the electronic parts remain dry and
no problems with the dielectric properties of water or corrosion of the electronic
parts. You could use oil but it has less heat capacity than water, from about 1/4 to
1/2. Also, makes a real mess if spilled. 

73
Bill wa4lav

________________________________________
From: Amps [amps-bounces at contesting.com] on behalf of Fuqua, Bill L [wlfuqu00 at uky.edu]
Sent: Thursday, June 06, 2013 11:04 AM
To: David Lisney; amps at contesting.com
Subject: Re: [Amps] Solid state amplifier cooling

     You have given me an idea.
May not be original but here it is.
One problem with the  heat transfer from the newer high power devices is making
a good reliable contact with the heat sink. You could use liquid cooling.
The thought is to mount the device on a flat  hollow channel carrying water with a rectangular hole and
seal or gasket such that the water comes into direct contact with the devices heat
dissipator. With adequate liquid fluid flow the device dissipate its heat directly to the
fluid, perhaps water, much better than you would have with a metal to metal to air
heat transfer scheme. Warping of the metal is not such a problem either.
73
Bill wa4lav


________________________________________
From: Amps [amps-bounces at contesting.com] on behalf of David Lisney [g0fvt at hotmail.com]
Sent: Thursday, June 06, 2013 10:35 AM
To: amps at contesting.com
Subject: Re: [Amps] Solid state amplifier cooling

I used to be in the PC overclocking scene many years ago, I used peltier heatpumps and a homebrew water cooling system to keep the CPUs cool, and it did let them operate at extremely high clock speeds... However, the CPUs rated power interpolated to about 40w a piece and the peltier devices were using over 70w a piece. There are published curves of heatpumping capability versus temperature differential etc, mine was quite a high differential trying to run CPUs at close to freezing with a water cooling circuit at probably 30c.

I found the biggest challenge was dealing with condensation, ambient air needs to be excluded from areas that are operating below the dew point. The second issue is algae growth!

One thing I did learn and will use again is the enormous heat capacity of water, on doing the maths it was surprising just how small a pump is required and just how little flow is required.

At the KW level I am sure a vehicle radiator with a very low power fan would suffice, in the case of my computer experiment I only had a few hundred watts to shed and a vehicle heater matrix easily coped (blown by a pair of 120mm 12v fans operated at 7v).

I think I would still use a computer fan in the vicinity of the PA section, obviously it is not just the output transistors that generate heat.

Watercooling also enables the fans to be remote and keeps the noise away from the operator.
Mind you a transistor PA with no tuning is easily remote controlled....

Just some thoughts, I have not posted for years but I do read this thread every day.

73 de David G0FVT
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