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A
reversible A/C system performs normal air- conditioning of an area
in summer. In addition to this, however, it is also designed to
reverse the refrigeration cycle in winter to supply heat to the
same area.
In
order to properly understand how it operates in general terms, let’s
look at the connection of the 4WV, and the direction of the refrigerant
flow in the two cases shown.
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“Summer”
operation
: The compressor
discharges superheated vapour into port 1
of the 4WV. The refrigerant emerges from the valve (by the bottom
right port) and is carried by the discharge pipework 2
towards the heat exchanger of the external unit (which now acts
as a condenser).
The
sub-cooled liquid emerges at 3
and then passes through the filter drier and the expansion device.
The expanded liquid then enters the heat exchanger of the internal
unit (which is now acting as an evaporator) through pipe 4.
The vapour produced is then drawn in through pipe 5
and directed by the slide valve of the 4WV towards the suction line
accumulator vessel 6
and then towards the intake of the compressor B.
In
this position of the 4WV, the heat absorbed on the interior of the
area is discharged to the exterior by the condenser: This
is the classical mode of operation for all air conditioning in summer.
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