The liquid refrigerant is then cooled in an internal heat exchanger, which increases the efficiency of the machine. The refrigerant is then expanded from high pressure to low pressure with an expansion valve. As a result, the temperature of the liquid refrigerant drops to the evaporation temperature of the low pressure.

At this low temperature, the refrigerant absorbs heat from a refrigerant circuit and evaporates. The useful refrigeration capacity is produced and the cold carrier is cooled.
The evaporated refrigerant with even low temperature is overheated in the internal refrigeration/heat exchanger. In compression refrigeration systems, the compressor would now come, which would compress the vapor-shaped refrigerant from low pressure to high pressure.

In absorption refrigeration machines, however, the property is used that the refrigerant dissolves ammonia very well in the solvent water. This is done in the absorber.
The vaporous ammonia is brought together there with the ammonia-containing aqueous solution, whereby the ammonia dissolves in the water and the ammonia concentration of the solution increases.
Heat is released during this process. The higher the temperature of the solution, the less ammonia can dissolve in the water. For this reason, the absorber is cooled. This waste heat is also delivered to the environment via the cooling circuit.

After the absorber, an ammonia-rich solution is present which can be pumped from low pressure to high pressure with a simple pump. Due to the incompressibility of a liquid, the current requirement of this pump is only a fraction of the current requirement of a comparable cold compressor.

Since the solubility of ammonia in water depends only on the pressure and the temperature, the ammonia recovers from the liquid even at high pressure if the temperature is increased only far enough. For this purpose, the rich solution is first preheated in a solution heat exchanger by internal heat recovery and then reaches the extractor.

In this system, the actual drive energy is supplied to the system. The solution is heated with the drive heat, which e.g. comes from a CHP, until the ammonia evaporates again. In the separator, the vaporous ammonia which flows upwardly to the cold section of the absorption refrigeration machine then separates from the ammonia-containing solution.

This solution is precooled in the solution heat exchanger and then expanded to low pressure in the throttle valve before it is returned to the absorber.