Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 64

(12) Circulating composition sensor (CS circuit) P-YMF-C only
• As shown in the drawing below; the CS circuit has the structure to bypass part of the gas discharged from the compres-
sor through the capillary tube to the suction side of the compressor, exchange heat before and after the capillary tube,
and produce two phase (gaseous and liquid) refrigerant at the capillary tube outlet. The dryness fraction of refrigerant at
the capillary tube outlet is estimated from the temperature of high pressure liquid refrigerant at the capillary tube inlet
(TH9) and the temperature of low pressure two phase (gaseous and liquid) refrigerant at the capillary outlet (TH2) and
the pressure (LPS) to calculate the composition of refrigerant circulating the refrigeration cycle
utilizing the characteristic that the temperature of two phase (gaseous and liquid) R407C under a specified pressure
changes according to the composition and dryness fraction (gas-liquid ratio in weight).
• The condensing temperature (Tc) and the evaporating temperature (Te) are calculated from
(HPS), and low pressure (LPS).
• The compressor frequency, the outdoor fan, and others are controlled according to the codensing temperature (Tc)
and the evaporating temperature (Te).
• CS circuit configuration (Outline drawing)
Four-way valve
Accumulator
Heat exchanger
TH9
TH2
LPS
CS circuit
-61-
( C). It is found by
C , high pressure