[volt-nuts] DIY Air bath

[Neville Michie]

I think it is because momentum is better conserved in a big swirl
whereas if you break the stirring into smaller cells they decay much  
faster leaving
dead spots or areas that are under mixed.
The shear of the large swirl draws in the peripheral zones and the  
density differentials
tend to aid the mixing.
What is certain is that quite a small amount of power in a grand  
swirl does as much good as much more power in smaller
distributed cells.

I have also used the technique with a window air condtioner. A  
special thermistor controlled circuit reduced the cycling of the
conditioner to less than 0.5 degrees. The compressor requires a  
special algorithm where when the compressor cuts out it is inhibited
from starting until it has had 120 seconds to lose its back pressure.  
Otherwise it starts or stops within a second of the setpoint crossing.
This algorithm increased the service life over other units that  
relied on the standard hysteresis based mechanical thermal switches.
Two small computer fans were enough to maintain the swirl in a 4 by 6  
metre laboratory.
I built more than 5 such installations.

cheers, Neville Michie

On 23/01/2012, at 4:13 PM, Charles P. Steinmetz wrote:

> Neville wrote:
>
>> One very effective technique is to instal a fan or fans to cause the
>> air to swirl around
>> the inside of the box in a cyclonic pattern. One fan, near the side,
>> mounted tangentially,
>> is usually enough. Random air stirring is not nearly so effective.
>
> Interesting.  I would have thought that a fan placement that  
> generates lots of random turbulence would be superior to a  
> "patterned" flow such as cyclonic.  I'd be concerned that a  
> patterned flow could sustain temperature zones because the air mass  
> might not mix thoroughly or as fast.
>
> Best regards,
>
> Charles
>
>
>
>
>
>
>
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