Controller functionality
Functions
• Day/night thermostat with ON/OFF or modulating principle
• Switch between thermostat settings via digital input
• Adaptive superheat control
• Adaptive liquid control
• Modulating PWM control of brine valve
• Start of defrost via schedule, digital input, network or setting display
• Natural, electric, simple hot gas, or warm brine defrost.
• Stop of defrost on time and/or temperature
• Coordination of defrosting among several controllers in a line-up
• Pulsing or ECO control of fans when thermostat is satisfied
• Appliance cleaning function for documentation of HACCP procedure
• Rail heat control via day/night load or dew point
• Door function
• Control of two compressors
• Control of night blinds
• Light control
• Heat thermostat
• High accuracy inputs:
◦
to guarantee a better measuring accuracy than stated in the standard EN ISO 23953-2 without subsequent
calibration (Pt1000 ohm sensor).
• Support of user defined temp. sensor type
• Integrated MODBUS communication
Injection control
Adaptive superheat control
Liquid injection in the evaporator is controlled by an electronic injection valve of the type AKV. The valve operates
as both expansion valve and solenoid valve. The controller opens and closes the valve based on sensor readings.
Figure 8: Adaptive superheat control with AKV valve
Danf
oss
84B2732
S2
AKV
p
e
The superheat is measured via a pressure sensor Pe and temperature sensor S2. By using a pressure sensor, and
temperature sensor a correct measurement of superheat is achieved under all conditions which ensures a very
robust and precise control. The signal from one pressure transmitter can be shared by max. 10 controllers, but only if
there is no significant pressure difference between the evaporators in question.
The function contains an adaptive algorithm which independently adjusts the valve’s opening so that the
evaporator constantly supplies optimum amount of refrigerant.
Adaptive liquid control
Adaptive liquid control is used in trans-critical CO
2
ejector systems, which allow liquid flow. When adaptive liquid
control is initiated, the superheat of the evaporator will be minimized so that a controlled amount of liquid is
present at the outlet of the evaporator.
© Danfoss | Climate Solutions | 2022.08
BC365212986197en-000201 | 9
AK-CC55 Compact