Performance Cruising Gemini 105Mc - How a Propane Refrigerator Works

Gemini 105Mc Owner’s Manual
53Copyright © 2004 Performance Cruising Inc.
How a Propane Refrigerator Works
The continuous absorption type of a cooling unit is oper-
ated by the application of a limited amount of heat fur-
nished by gas. No moving parts are employed. The unit
consists of four parts: the boiler, condenser, evaporator
and absorber.
When the unit operates on propane, the heat is supplied
by a burner which is fitted underneath the central tube
(A) .
The unit is charged consisting of a quantity of ammonia,
water and hydrogen at a sufficient pressure to condense
ammonia at the room temperature for which the unit is
designed. When heat is supplied to the boiler system,
bubbles of ammonia gas are produced which
rise and carry with them, quantities of weak
ammonia solution through the siphon pump
- (C). This weak solution passes into the
tube (D), while the ammonia vapor passes
into the vapor pipe (E), and on to the water
separator. Here any water vapor is con-
densed and runs back to the boiler system,
leaving the dry ammonia vapor to pass to
the condenser. Air circulating over the fins
of the condenser removes heat from the
ammonia vapor to cause it to condense to
liquid ammonia from were it flows into the
evaporator.
The evaporator is supplied with hydrogen.
The hydrogen passes across the surface of
the ammonia and lowers the ammonia vapor
pressure sufficiently to allow the liquid
ammonia to evaporate. The evaporation of
the ammonia extracts heat from the evapo-
rator, which in turn extracts heat from the
food storage space, as described above,
thereby lowering the temperature inside
the refrigerator.
The mixture of ammonia and hydrogen va-
por passes from the evaporator to the ab-
sorber.
Entering the upper portion of the absorber is a continuous
trickle of weak ammonia solution fed by gravity from the
tube (D). This weak solution, flowing down through the
absorber, comes in contact with the mixed ammonia and
hydrogen gases which readily absorbs the ammonia from
the mixture, leaving the hydrogen free to rise through the
absorber coil and to return to the evaporator. The hydro-
gen thus circulates continuously between the absorber and
the evaporator.
The strong ammonia solution produced in the absorber
flows down to the absorber vessel and from there to the
boiler system, thus completing the cycle of operation.
The liquid circulation of the unit is purely gravitational.
How a Propane Refrigerator Works
Heat is generated in the absorber by the process of absorp-
tion. This heat must be dissipated into the surrounding air.
Heat must also be dissipated from the condenser in order to
cool the ammonia vapor sufficiently for it to liquefy. Free air
circulation is therefore necessary over the absorber and
condenser.
The whole unit operates by the heat applied to the boiler
system and it is of paramount importance that this heat is
kept within the necessary limits and is properly applied.