Control concepts and activation of the solenoid valves
Control range
To cover the extended control range, a CRII unit is mounted on each cylinder bank (see figures below) and the system controller is programmed accordingly. This achieves higher efficiency and control accuracy of the system, especially at low loads.
Capacity control down to 10% (5% for tandem compressors) is generally only possible with an IQ MODULE (CM-RC-01 or CM-RC-02), as this is the only way to achieve the necessary high cycling rate.
Activation of the solenoid valves
Specially designed solenoid valves control the capacity regulators. They are marked "CR" or "CRII" and are designed for high cycling rates.
- With a view to achieving ideal part load efficiency and a long service life, only one of the two valves should be intermittently activated in 4-cylinder compressors in the 100% .. 50% capacity range. At load conditions < 50%, one valve is activated permanently, the second valve intermittently.
- This applies similarly to 6-cylinder compressors in the ranges 100% .. 66% and 66% .. 33% and to 8-cylinder compressors for HC, HFC and HFO in the range 100 .. 50%. (Virtually stepless capacity control is not possible with 8-cylinder compressors for R744.)
This method significantly reduces the number of switching intervals for each valve and results in a particularly long service life. To ensure that the valves switch at regular intervals, a regular (automatic) sequence change can also be implemented.
Average factors for power consumption
The resulting power consumption when using capacity control is listed in the BITZER SOFTWARE after the capacity level has been selected.