Electronic Expansion Valve Pi Control R-410A Circuit; Electronic Expansion Valve Pi Control R-134A Circuit - Daikin ALTHERMA HT ERSQ 011 AA Service Manual

ESIE09-08A
Electronic Expansion Valve PI Control R-410A
2.3
circuit
Main Electronic Expansion Valve EV1 Control - Outdoor Unit
Carries out the electronic expansion valve (Y1E) PI control to maintain the evaporator outlet superheated
degree (SH) at constant during heating operation to make maximum use of the outdoor unit heat
exchanger (evaporator).
SH = Ts1 - Te
The optimum initial value of the evaporator outlet superheated degree is 3°C, but varies depending on the
discharge pipe superheated degree of inverter compressor.
Subcooling Electronic Expansion Valve EV3 Control - Outdoor Unit
Makes PI control of the electronic expansion valve (Y3E) to keep the superheated degree
outlet gas pipe on the evaporator side for the full use of the subcooling heat exchanger.
SH = Tsh- Te
Electronic Expansion Valve K1E Control - Indoor Unit
Carries out the electronic expansion valve (K1E) PI control to maintain the condensor outlet subcooled
degree (SC) at constant during heating operation to make maximum use of the indoor unit heat exchanger
(condensor).
SC = Tc - R3T
Electronic Expansion Valve PI Control R-134a
2.4
circuit
Electronic Expansion Valve K2E Control - Indoor Unit
Carries out the electronic expansion valve (K1E) PI control to maintain the condensor outlet subcooled
degree (SC) at constant during heating operation to make maximum use of the indoor unit heat exchanger
(condensor).
SC = Tc - R7T
Function
SH : Evaporator outlet superheated degree (°C)
Ts1 : Suction pipe temperature detected by thermistor R3T
(°C)
Te : Low pressure equivalent saturation temperature (°C)
SH : Outlet superheated degree of evaporator (C)
Tsh : Suction pipe temperature detected with the
thermistor R4T (C)
Te : Low pressure equivalent saturation temperature (C)
Basic Control
of the
(SH)
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