Actual Vapor Compression Cycle:
For thermodynamic study of the refrigeration systems, refer to the ideal behaviour of the fluid & neglect any unrelated factors. In real practice however, these factors contain important effect on the COP & refrigerating effect of the refrigeration cycle. In this section, we go for a thorough analysis of these external factors & their effect on the total system performance.
The real vapor compression cycle is illustrated in Fig 10. With the help of a T-s diagram for the operating pressure limits p1 & p2. The definite compression follows 1 - 2' rather causing considerable difference because of the irreversibility's belonged with the compression procedure 1 - 2. Again, throughout condensation and sub cooling by approximate 5 to 10 K (2'-4) in the condenser, the pressure before throttling drops approximate of 2%. The throttled condensate enters into the evaporator at a pressure a bit higher than the evaporator pressure p1. This irreversibility causes important distortion in the ideal cycle, so indicating a significant decrease in the COP. Also, if we refer the suction & discharge losses in the compressor, the COP value would reduce further.
T-S Diagram of Actual Vapour Compression Refrigeration Cycle