The Absorption Refrigeration Unit, "TRAB", developed by EDIBON, is a complete laboratory unit for the demonstration of absorption refrigeration.
This unit is provided with a dual power source (heat source) of LPG and electricity. A pressure regulator to adapt the gas to the corresponding inlet pressure (30 – 50 mbar) is supplied for the operation with LPG.
The fluid used in the refrigeration cycle of the "TRAB" unit is a solution of water and ammonia (NH3), being ammonia the refrigerant and water the absorbent. An important advantage is that these agents are totally innocuous for the environment. The cycle uses the great affinity of ammonia with the water, being the ammonia used as refrigerant since it is easily absorbed by water.
The water and ammonia solution is heated at a high pressure in the generator or heater. Two substances are separated then by boiling: on one hand, vapour with a high concentration of ammonia, called concentrated solution, and on the other hand, a liquid solution with a low concentration of ammonia, called diluted or poor solution.
Vapour passes through a condenser (finned exchanger) where it is cooled until it condenses and passes to liquid state, reducing its temperature.
This ammonia concentrated solution enters a heat exchanger, where it is further cooled and its pressure is reduced to enter the evaporator.
Due to this pressure difference, it is evaporated at a low temperature.
The unit includes a tank for the absorber, where the solution rich in ammonia in liquid state formed by the absorber and the ammonia vapour from the evaporator stay together.
The absorber makes it possible to obtain a low pressure in the evaporator, so that the refrigerant (ammonia) boils at a lower temperature, taking the required heat from the water, reducing its temperature.
The liquid solution rich in ammonia coming from the absorber is heated in the generator to separate the pure ammonia vapours and the water (absorber). Ammonia vapours go to the condenser and the poor solution goes to the absorber, where the absorption of the ammonia in vapour state is generated again.