User:WilfriedC/Playground/Phase Envelope

A Phase Envelope is a diagram which shows the vapor-liquid equilibrium behavior of a fluid at different pressures and temperatures but at a constant composition.

A phase envelope shows both the boiling and dew point curve. Besides these two lines phase envelopes exhibit the highest temperature of the liquid-vapor equilibrium curve ('cricondentherm'), the highest pressure ('cricondenbar'), and the critical point of the fluid where the dew and boiling curves meet and both phases become indistinguishable.

The phase envelope surrounds an area where the two phases vapor and liquid coexists. Above and left of the boiling point curve at higher pressures and lower temperatures only the liquid phase exists and below and right of the dew point curve at lower pressures and higher pressure only the vapor phase exists.

Phase envelopes are typically used for reservoir fluid like natural gases.