Re: [VAC] [Fwd: Re: Willcool]

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxx>]

Phil, I'm quite aware of the definition of BTU. I learned that in
thermodynamics 301 back about 1962. My response from Willcool does not
answer my question. Power in KWH for a total production of BTU while the
web page shows 120 volts 1 amp as the power requirement is not
consistent with the BTU/Hr rate needed to counteract heat production by
occupants and heat infiltration into a space. If all these numbers are
taken at their face value and given units, the Willcool produces 12000
BTU over a period of about 8 hours (time to consume 1 KWH at 1 amp and
120 volts) which is a refrigeration rate of 1500 BTU/Hr, far smaller
than most air conditioners. Yet the power consumption is very much
smaller than most air conditioners.

As all contemporary air conditioning is based on some variation of a
heat transfer cycle where the heat is removed from the conditioned space
by some mechanism (generally a Carnot refrigeration cycle based on
compression/expansion or an adsorption version of the same) that raises
the temperature of the refrigerating medium for rejection to some space
other than the space being cooled (there is only HEAT, there is no COOL)
I question the stand alone single unit's performance further.

I think it's still likely to be a bucket of ice with a fan... Which is
not energy efficient in the middle of the boonies.

I suppose it would be possible to reject heat to a bucket of water, but
it takes only 122 BTU to raise a pound of water from 80°F to boiling. It
takes 550 BTU to boil that pound of water, but steam is not what one
wants introduced into an environment where one is living or wishes to
cool. If all the waste heat (and only 12000 BTU was waste heat) was
allowed to come back to the "cooled" space there would be no temperature
change. Since mechanical processes are no 100% efficient, releasing the
steam would actually raise the temperature of the "conditioned" space
instead of cooling it. A net loss. And in normal refrigeration cycles,
their efficiency falls as the rejection temperature rises, hence most
prefer to use a lot of outside air thereby raising the environmental
temperature for those outside the conditioned space. This old atmosphere
is not so large that reject and waste heat can't raise its temperature.
Some claim that is as much effect as green house gasses. And we all do
it. Essentially every bit of fuel consumed goes to heat the atmosphere,
whether that fuel is used to create electricity, or move vehicles, or
heat a pot on the stove. It all ends up as heat to warm the atmosphere.

I think my next question to Willcool will be, "May I see a copy of the
owner's manual?"

Gerald J.