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Re: Cooling your components

While I agree with your point that losses represent an avoidable loss of
power, some power dissipation in components cannot be eliminated, and some
people can't afford high-quality dielectrics (no offense to anyone meant.)
So a cooling system can be a good idea in some coils, especially large ones.

Liquid N2, although great for playing around with and making fog onstage en
masse, is not a very good coolant. Its specific heat is relatively low
(about a quarter of that of water, and half that of oil), which means that
it doesn't carry much energy, and will therefore warm up quickly without
changing the temperature of what it's cooling much. It is only used for
cooling in cryogenic applications (where something has to be extremely cold,
not just at room temperature.) It also has the problem of being relatively
hard to handle and produce (which you would have to do to maintain a cooling
system at reasonable cost and convenience), and of course has the potential
for injury by frostbite.

For these reasons, systems designed to keep components from overheating,
rather than chilling them, generally use water (only in applications where
components can be protected from corrosion, and therefore unsuitable for a
TC) or oil, which are circulated through a refrigeration unit, which ideally
is controlled by a thermostat, so as not to overcool components or
freeze/gel the coolant.

Tesla List wrote:

> Original Poster: Bert Hickman <bert.hickman-at-aquila-dot-com>
>
> Tesla List wrote:
> >
> > Original Poster: "JimmyD" <jim_del-at-email.msn-dot-com>
> >
> > I've read alot on the list about components failing because of
> > heating(overheating).
> >
> > Has anybody tried cooling the components in liquid nitrogen?
> >
> > Just a thought...
> >
> > << Jim >>
>
> Jim,
>
> Tesla often speculated about reducing his system losses by running
> components of his systems under liquid air. We now know that MOST of the
> losses in the primary circuit come from the sparkgap, and most in the
> secondary come from the earth ground and streamer losses (for sparking
> coils). Tesla tried to eliminate the streamer losses - we want to
> maximize them!
>
> Component failures from overheating usually occur in the tank cap, and
> this typically stems from using lossy dielectrics such as glass, mylar,
> PVC, etc. Using a low loss dielectric such as Polypropylene or
> Polyethylene will solve the overheating problem at its source. Remember
> that excessive heating represents an energy loss, and this loss will
> reduce the amount of energy that makes it to your streamers. Loss
> prevention by using good dielectrics will be most likely be more
> effective (and less expensive) than cooling with liquid nitrogen.
> Cooling the tank cap in liquid nitrogen may also create other problems
> due to the dielectric becoming brittle, and the dielectric oil jelling.
>
> -- Bert --

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