NA-2243 -- A Property Diagram to Illustrate Irreversibilities in the R12 Refrigeration Cycle

Availability is the thermodynamic property which measures the potential of a system to do work when restricted by the inevitable surroundings at T_o and P_o. Unlike energy, availability is not conserved and any degradation by friction, or by heat transfers through a temperature difference, results in destruction of availability. The destruction of availability is called irreversibility.

This paper presents a property diagram (Fig. 1), for R12, which allows convenient availability analyses of vapor-compression refrigeration cycles. The diagram graphically displays the irreversibilities occurring within the cycle while also illustrating the availability flow into or out of the system.