In the HT circuit heat QH is removed from CO2 gas cooler at gliding
temperature varying from T9 to Tc by an external cooling medium.
The CO2 is expanded, then evaporated at evaporating
temperature of T5 in the cascade heat exchanger. Then it is compressed
in the CO2 compressor and discharged into the gas cooler.
Figs. 2 and 3 shows the thermodynamic processes for CO2 and propylene
on P–h and T–s diagrams along with their saturation lines.