Parallel compounding with a single liquid subcooler

The figure below shows a schematic example of an economised trio system with only one (common) liquid subcooler. Individual solenoid valves for each economised compressor are required. For part load operation, the liquid subcooler must be selected very carefully (Selecting the liquid subcooler) to ensure good refrigerant distribution. Also, oil return has to be ensured for operation at lower capacities and lower gas flow velocities. The same applies to the expansion valve for the liquid subcooler. In case of operation over a larger capacity range, the use of two expansion valves (e.g. 100 % and 33 % of total capacity) is preferred. Additionally, upstream of each thermostatic expansion valve a solenoid valve in the liquid line is required.

Alternatively, a single electronic expansion valve can be used instead of one or several thermostatic expansion valves.