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Re: Heat Pumps...?



On Mon, 03 Feb 1997 21:15:55 EST Dwight K. Souder said:
John Sample had this right, but you may not have understood some of his
points.
The diagram looks like a cut-away of a window air-conditioner.
The description I'll try to explain is for summer cooling. From the
compressor, the freon travels through the tubes in the back where a fan
blows over them and the diagram show that the freon is "hot". It then

The freon comes out of the compressor as a gas, liquids are not compressable
and if you get liquid forming in a compressor something has to give. You
probably stall the motor and blow a fuse our burn up the motor!

goes through a condensor (?) and through a capillary tube. From the

Since we get hot gas from the compressor we need the condensor to turn
it into a liquid. You may have seen the condensor for your car AC. It
looks like an extra radiator in front of your engine cooling radiator.
Air blows through the condensor cooling the freon causing it to liquify.
Being a liquid it takes less space and we can transport all we need in
a small tube. The small tube also causes a pressure drop. Some systems
use a small orifice to create the pressure drop.

capillary tube, the tube gets larger and passes in front of the
air-conditioner (the part inside of the house) where the freon is a gas.

As conduction brings heat to the liquid freon under low pressure it will
evaporate, maintining its low temperature, and continuing to absorb heat.
The evaporation takes place in the "evaporator".
A regulator valve (expansion valve) is controled by temperature at the
evaporator outlet or by pressure in the evaporator to maintain a flow
of liquid freon which matches the rate of freon evaporation. When freon
levels are low the flow can not keep up with evaporation, the temperature
in the evaporator rises, and the AC no longer functions effectively

Air is circulated over the tubes and the tubes return back to the
compressor.
Personally, I think this is backwards. It was my understanding
that the freon from the compressor is compressed into a liquid, where it
Compressed into a hot gas and then cooled in the condensor (giving up heat)

releases its heat energy to the outside. The freon is then circulated to
the front where it picks up heat energy and the freon goes from a liquid
into a gas. The gas is then brought into the back and is compressed in
the capillary tube and back into the compressor where it releases a large

The capillary comes before the evaporator to produce a pressure drop. The
line into the compressor is relatively large to carry the large volume
of gas.

amount of heat energy.
Can anyone help? Can anyone explain steb by step how a heat pump
works and what goes on in an air-conditioner/heater? What happens when
an air-conditioner is put into reverse and becomes a heater?

In reverse the condensor becomes the evaporator and the evaporator becomes
the compressor. In either event the compressor is outside so you don't have
to listen to it. There are just valves connected to the compressor inlet
and outlet allowing the direction of flow through the rest of the system
to be reversed. The heat pump is a neat trick because the energy brought
into the house (assuming reasonable outside temperatures) far exceeds the
electrical energy consumed.

Any help would be very much appreciated.

Thanks,
Dwight
dsouder@juno.com