A refrigeration plant is used for cooling. The most important component of every refrigeration plant is the chiller. The function of the chiller is based on the thermodynamic cycle (Carnot cycle), where heat is absorbed below the ambient temperature and given off at a higher temperature.
The decisive difference between the most important types or vapour-compression refrigerators and sorption refrigerators is the method in which the energy is applied. On vapour-compression refrigerators, the primary energy is fully applied via the electrical drive, whereas only heat is applied with the sorption refrigerator.

The vapour-compressor refrigerator features a compressor (K) with an electrical drive, an expansion valve (E), as well as two heat exchangers (C, V).

Control of the cooling capacityIn the so-called thermodynamic cycle, the compressor first pressurizes the refrigerant vapour. In the downstream condenser (C), the refrigerant is condensed. The liquid refrigerant is depressurized in the expansion valve. In the expansion process, the refrigerant pressure is reduced and the refrigerant cools down. In the evaporator (V), the refrigerant absorbs the input heat from the cooling zone. The compressor again intakes the evaporated refrigerant and the cycle is thus completed.

The control of the cooling capacity is undertaken step-by-step in a conventional manner by switching-off cylinders and distributing the cooling capacity over several compressors. A continuous improvement of the control process and reduction of losses can be achieved by continuous speed control of the motor using frequency inverters and a change of the control concept.

With the inverters of the H-Max series, Eaton offers a special HVAC frequency inverter with a co-ordinated control strategy and special properties.