Daikin EWAQ032BAW - Electronic Expansion Valve PI Control; Subcooling Electronic Expansion Valve EV2 Control

Basic Control ESIE11-05
44 Functional Description
2.3 Electronic Expansion Valve PI Control
Heating operation
*1
EXV1 is controlled towards superheat (SH)
*2
K11 & K21E are controlled towards subcool
Cooling operation
*1
EXV1: fully open
*2
K11 & K21E are controlled towards superheat
Subcooling electronic expansion valve EV2 control
Makes PI control of the electronic expansion valve (Y2E) to keep the superheated degree of the
outlet gas pipe on the evaporator side for the full use of the subcooling heat exchanger.
SH = Ts- Te SH: Evaporator outlet superheated degree (C)
Ts: Suction pipe temperature detected by
thermistor R6T (R7T) (C)
Te: Low pressure equivalent saturation
temperature (C)
SC = Tc - Tl SC: Subcool (°C)
Tc: Saturated condenser temperature
Tl: Liquid temperature R6T (°C)
Tl
Ts
EXV1
(*1)
outdoor
unit
hydrobox
PHE
K11 & K21E
(*2)
SH = Ts- Te SH: Evaporator outlet superheated degree (C)
Ts: Suction pipe temperature detected by
thermistor R6T (R7T) (C)
Te: Low pressure equivalent saturation
temperature (C)
Te
Ts
EXV1
(*1)
outdoor
unit
hydrobox
K11 & K21E
(*2)
SH = Tsh- Te SH: Evaporator outlet superheated degree (C)
Tsh: Suction pipe temperature detected by
thermistor R5T (C)
Te: Low pressure equivalent saturation
temperature (C)