A New Phase Diagram: The T-S Diagram


TS Diagram

  • We only consider pure substances
  • Two-phase envelope, similar to PV Diagram
  • Subcooled


    compressed liquids

    have lower entropy than saturated liquids
  • Superheated vapors

    have higher entropy than

    saturated vapors

  • The entropy of a

    saturated vapor-liquid mixture

    lies below the entropy of the saturated vapor (at the same T & P) and above the entropy of the saturated liquid at the same T & P.
Compressed or
Subcooled Liquid:
Superheated Vapor:
Vapor -Liquid Mixture:
TS diagram showing the two-phase envelope, the subcooled liquid, two-phase and superheated vapor regions.
Subcooled Liquid
Superheated Vapor
Saturated Vapor - Liquid Mixture
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Ch 7, Lesson B, Page 8 - A New Phase Diagram: The T-S Diagram