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8
Refrigerator Service ManualN611v, N811v Models
Theory of Operation - cont’d.
A rich solution (RS) leaves the absorber vessel and passes
through the liquid heat exchanger to the bottom of the pump
tube. Utilizing an AC cartridge heater or a LP gas burner, a
precise heat is applied to this area which in turn causes the
temperature of the solution to rise. This temperature increase
causes ammonia and some water vapor to be driven out of
the solution, forming vapor bubbles which push columns of
liquid up the pump tube.
As these columns of liquid exit the pump tube the liquid falls
downward through the rectifi er where the temperature is
increased causing additional ammonia vapor to be released.
The remaining liquid, now a weak ammonia-water solution
(WS), fl ows through the external shell of the liquid heat
exchanger where it transfers its residual heat to the rich
solution (RS) and enters the top of the absorber coil at a
reduced temperature. The ammonia-water vapor passes
through the water separator whose reduced temperature
causes any water vapor to condense and drop back down to
the boiler mixing with the existing weak solution (WS). The
ammonia vapor (AV) rises and enters the condenser where
it condenses (liquefi es) into pure liquid ammonia (LA). The
liquid ammonia, via gravity, drops into the tubular coil of the
freezer and cabinet evaporators and wets the internal surface
of the tubes.
The weak ammonia-hydrogen gas that was previously
released at the top of the absorber coil passes over the
wetted surfaces of the evaporator tubing causing the liquid
ammonia to evaporate into the hydrogen. The now rich
ammonia-hydrogen gas mixture (RG) draws heat from inside
the refrigerator. The weight of the hydrogen-ammonia gas
mixture (RG) is heavier than that of the weak gas (WG).
Consequently, it falls through the gas heat exchanger into the
top of the absorber vessel. From this point it enters the bottom
of the absorber coil.
The rich ammonia-hydrogen gas mixture (RG) travels up
through the absorber and makes contact with the weak
solution (WS) traveling down from the top of the absorber. As
the weak solution (WS) drops through the absorber it absorbs
the ammonia from the rich ammonia-hydrogen gas mixture
(RS). The relatively pure hydrogen (WG) exits the top of the
absorber coils to the evaporator and the rich solution falls to
the bottom of the absorber vessel where the cycle starts again.
Gas Absorption System
Fig. 3 - Gas Absorption System
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