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"MICHEL SAMSON" wrote to "ALL" (10 Jul 03  14:45:00)
 --- on the topic of "Air conditioning"

 MS> could try a question of my own.  :-)  That one is about a whole
 MS> different area as it relates to regulating temperature in homes...
 MS> Persons like me who pay a rent don't always find it suitable to have an
 MS> air conditioner that blocks one of their few windows, makes a neighbour
 MS> want to close his and call for a landlord's attention because of a
 MS> summer bill...  I'd like to know what alternatives other than removing
 MS> humidity are available or, at least, imaginable;

Lately I've seen these portable air conditioners on wheels for rent. The
thing looks a bit like a small fridge on wheels with two large dryer
style hoses on it. It seems to be a sort of self-contained unit of some
kind. I'm guessing these large diameter air hoses are to push warm air
out and force cold air into something else, I'm thinking of the central
air furnace for example. In any case the best all around system seems
without doubt to be the heatpump/airconditioner all-in-one combo. It
takes some amortization to get the benefits but what you save on
oil/gas/electricity in heating more than compensates for the summer air
conditioning season. Some heatpumps even work as low as -10'C which is a
pretty cold monthly average in February. I'm really impressed with the
technology and this is much more efficient than say a window unit.


 MS>   i'm thinking of
 MS> refrigerators built in reverse where the heat could be pumped out of
 MS> the room and concentrated inside, say, a bucket of water that would
 MS> eventually evacuate the accumulated heat thru the kitchen's sink...  I

Build a room like a refrigerator. Butcher shops have them. Pipe
refrigerant into well insulated walls. More details wait...


 MS> I once wondered if more sophisticated systems are not possible:
 MS> What's feasible and what's not?

Sometimes a trip back in history can bring to light systems which have
already proven themselves. For example I had this little old bar fridge
which worked on electricity but there was no motor at all. Yet it kept
the ice cubes frozen and the beer cool. Being curious I came to
understand it worked on a slightly different principle than our common
compressor technology. It worked on a principle called absorption.
Basically, instead of a compressor, a heat source causes phase changes
in 2 different liquids with different transition temperatures. Here is
an excerpt of a discussion I had in an echo many years ago:

>
  The Absorption Cycle

 I must admit to having taken for granted the absorption system as was
 and is used in gas and electric heated refrigerators. My assumption about
 the basic principle being that of phase transitions of a volatile liquid
 was probably correct and left it at that as pretty much all the answers
 to my question here seemed to imply. Well, I've learned some.

 To really understand how this system works a simple analogy can be made
 which revealed itself to me in a sudden flash of insight. Basically,
 just take example on how our Earth's rain cycle works.

 Briefly, the Sun heats the ocean, evaporation takes place, and the ocean
 cools. The vapour rises into the atmosphere, gives up its heat to space,
 and condenses into rain droplets. The rain falls to Earth, cools the
 air, and the cycle starts over.

 This example with some improvements is pretty much how the absorption
 system works. A strong water and ammonia solution is heated and the
 vapour evaporates. Water stays behind in the separator and the ammonia
 gas rises up into the condenser where it gives up its heat and
 precipitates as a liquid.

 The now cold liquid ammonia is passed through the food storage unit and
 absorbs its heat. The ammonia next returns to gas form, falls by gravity
 and by residual partial pressure down into a collector where it is
 re-absorb into solution by the previously separated water and the cycle
 starts over.

 Now there are a few more refinements in the system such as the addition
 of hydrogen in one of the flowing loops so as to carry the residual
 pressure. There are also strategically placed elbows which keep
 pressures separated between the main loops as well as a few more
 condenser coils which further cool the ammonia and water before remixing
 to solution.

 However, the absorption cycle is pretty much like our own Earth's rain
 cycle. Other gases are used of course but it's basically a play between
 heat which is transported as a vapour to a higher altitude and gravity
 which causes the precipitate to fall when it condenses. Heat is thus
 simply carried away from the food as the ammonia rains down so to speak.
 Wonderful!

>

I was thinking that such a system could be adapted to ariconditioning
and directly powered by sunshine say with a parabolic concentrator
mirror of some kind. Thus the brighter the Sun shines the more the
system cools!

 Mike
 ****

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