At the end of the 19th century most refrigeration equipment was based on the absorption principle. This technology did not need electrical energy, its main driving energy heat source came from a steam boiler or a burner.
Later in the 1950s, due to low energy prices the hermetic compressors came on the market and the absorption technology was moved into the background. It remained used only in a few niche areas where its high reliability and ability to cool down to extremely low temperature was an advantage.
At the end of the last century, after the first energy crisis, absorption technology has again attracted attention, as it can be powered by residual heat, thus reducing primary energy consumption.
Nowadays thermodynamic processes of absorption combined with modern control techniques result in high-efficient plants. They are the most environmental friendly and energy-saving form of refrigeration through the use of the natural refrigerant ammonia and the drive with residual heat.