Many cooling systems will have a split between the material that flows pass
the heat source and the cooling reservoir. Only the initial material would
need to be very pure. The reservoir could be ’tap water’.
Car radiators do this with primary heat collection being liquid and
secondary cooling provided by airflow. Often the initial material is
specialized for temperature range and aiming for a very broad liquid state.
The best examples of broad liquid state are the uses of liquid sodium &
lead in nuclear reactors. They have a liquid range of a couple thousand
degrees (range from being a solid to a liquid), where water is only 100
degrees.
--
Dave
On July 13, 2018 at 12:18:55 PM, `Richard Knoppow (dickburk@xxxxxxxxxxxxx)
wrote:
I was thinking of that when I posed my question.
FWIW, pure water is a good insulator. It also has a high
specific heat. For those reasons water was used to cool the large
vacuum tubes used in radio transmitters and elsewhere. I think it
still is for some applications. The water had to be very pure
otherwise there was enough leakage to cause hydrolysis and
deposition of material in the cooling system. After about 1935
air cooled tubes became available. The air cooled tubes were at
first just the same ones but with large finned radiators brazed
to the plates. However, while air cooling solved some problems
the tubes had about half the power handling capability of their
water cooled counterparts. All replaced with solid state devices
in modern radio transmitters except for the very highest power ones.
Many early high power broadcast stations (50KW or more) had
a swimming pool sized pond for cooling the heat exchanger water.
I can't remember what the source of cooling water was i.e.
if the radio stations had to have their own distilling apparatus
or if they could buy suitable water.
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
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