A refrigeration process includes a compressor, as explained in detail in Chapter 5, because it is necessary to change the boiling point of the refrigerant, which is done by controlling the pressure. Chapter 3 shows that the work required for compression is well approximated as equal to the change in enthalpy. Use Appendix F to find the change in specific enthalpy for each of the scenarios A through C.

Transcribed Image Text:

A. Freon 22 enters the compressor as saturated vapor at P = 0.5 bar and exits the compressor at P = 2 bar and T = 20°C. B. Freon 22 enters the compressor as saturated vapor at P = 2 bar and exists the compressor at P = 8 bar and T = 60°C. C. Freon 22 enters the compressor as saturated vapor at P = 5 bar and exists the compressor at P = 20 bar and T = 80°C. D. In these three compressors, the inlet and outlet pressures varied considerably, but the "compres- sion ratio" P/Pwas always 4. What do you notice about the changes in enthalpy for the three cases?