Master And Slave Unit's Eev Control - LG Multi V Water IV ARNU07GTU 2 Series Service Manual

Function

1.3 Master and slave Unit's EEV control

(1) Main EEV control
Main EEV operates with fuzzy control rules to keep the degree of super Heat(Superheat) (about 3°C)at
the evaporator outlet stable during heating mode
The degree of Superheat = Tsuction - Tevaporation
Tsuction : temperature at suction pipe sensor(°C)
Tevaporation : evaporation temperature equivalent to low pressure(°C)
(2) Subcooling EEV control(about 15°C)
Subcooling EEV works with fuzzy rules to keep the degree of Subcool at the outlet of subcooler during
cooling mode
The degree of Subcool = Tcondensation - Tliquid
Tliquid : temperature at outlet of subcooler(°C)
Tcondensation : condensation temperature equivalent to high pressure(°C)
(3) Avoiding excessive high discharge temperature : when main EEV opens some given opening (R410A :
800 pls) and discharge temperature is above 85°C in heating operation, subcooling EEV may control
the "subcooling out temperature-evaporating temperature" to be some given difference.
(4) Vapor injection flow-rate control at heating mode
The degree of Superheat (VI_SH) = Subcooler out(℃) – Subcooler in(℃)
- Td ≤ 80℃ : VI_SH = 3℃
- 80℃<Td ≤ 90℃ : VI_SH = -2*Td/10 + 19
- 90℃<Td : VI_SH = 1℃
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