1st, they don't use water. As I said in the post, Water, Vapor phase
cooling is too hot for SS amps/circuits. 100C will work, but the life
of the device would be drastically shortened. Vapor phase cooling CPUs
is done with a liquid that vaporized at a much lower temperature than water.
In modern RF power transistors, there is very little minority carrier
migration, but much above 70C this happens more readily.
I don't know the calories per minute limit for the closed circuit, CPU
cooling, but using chilled water on a 12 KW, out RF generator (class C)
only required a gentle flow out of a quarter inch hole. (3/8ths and 1/2"
hose to the clear plastic monitor))
Computers used by diehard gamers who push the CPU's limits, by over
clocking ( seeds over the published ratings) and heavy use of the CPU,
regularly use "Open circuit" , or closed circuit chilled water for
cooling rather than the radiator mounted on the computer case using two,
or 4 fans. OTOH the commercial, closed circuit cooling with the radiator
on the tower are a somewhat easy/shortcut to handle the heat from some
standard, 8 core CPUs running at 4.7 GHz and faster. Some come with a
single core closed circuit cooler
From experience, I doubt any of these would be adequate to cool the
dissipation of a legal limit amp on digital. Many full size computer
tower cases come already equipped/designed for the use on an external
source and discharge of coolant.
It's not uncommon to see water cooling used on both the CPU and vireo
card, but for serious heat, they, like water cooled ham amps, resort to
an externally supplied coolant.
I would not expect any of these multiple fan CPU coolers to
satisfactorily cool a legal limit SS amp.
The multi fan units are quiet, but they can have the fans configured in
a push pull arrangement for "some" increase in capacity and noise.
Using the double size radiator requires careful selection of the tower
and often, like home brew amps may require some metal work.
Sounds like a good experiment for someone to find out just how much heat
one of these could handle, or how the cooling circuit would need to be
modified.
73, Roger (K8RI).
On 2/17/2017 4:14 PM, Jim Thomson wrote:
Date: Fri, 17 Feb 2017 12:53:53 -0500
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Subject: Re: [Amps] SS amps watercooling - was PowerGenius XL
Water is far easier to clean up, leaves less mess, and is more efficient
at heat transfer. The vapor phase cooling used in computer CPU cooling
is efficient, but less tolerant of leaks, difficult to charge, and works
at lower temps..
Vapor phase water cooling is very efficient (already covered by another
poster) for tubes as vaporizing 1 gram (1 cc) of water uses 539 calories
(at 100 C - too hot for SS), while heating or cooling water 1 deg C
takes 1 calorie.
Vapor phase cooling has no moving parts except for a fan(s) at the radiator.
73, Roger (K8RI)
## How the heck do they do vapor phase cooling with a cpu ? Vapor phase
cooling works on the premise that the water is brought up to a boil. And thats
with normal sea level pressure. Put the system loop under pressure, and the
boiling point will rise by a bunch. Will a cpu handle 212 F ?
## I dont think these LDMOS devices will handle 212 F temps ?? If they
do, then vapor phase cooling would be ideal, and the pump can be eliminated,
and the external rad + fan could be made very small..... like the alpha vapor
phase
cooled amp.
Jim VE7RF
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