1. Create the stream with required composition.
2. Enter the desired temperature in the stream properties.
3. Set the vapor fraction to 0.
Pressure calculated by HYSYS will be the vapor pressure of that stream. Note that HYSYS is actually calculating the bubble pressure when vapor fr is set to 0. But bubble pressure is the vapor pressure at the specified temperature (good for any temperatures below critical temperature).
Note that vapour pressure greater than operating pressure (for a
multicomponent mixtures) just means that the liquid is flashing (Vapor-liquid
mixture).
To keep a liquid phase the operating pressure of a two phase stream is usually greater than the liquid vapour pressure. Otherwise the liquid would flash so that the vapour pressure of the new liquid is below the operating pressure. This means for a two phase multicomponent mixture flow, the vapour pressure of liquid at operating temperature (not entire mixture) is equal to the operating pressure.
To keep a liquid phase the operating pressure of a two phase stream is usually greater than the liquid vapour pressure. Otherwise the liquid would flash so that the vapour pressure of the new liquid is below the operating pressure. This means for a two phase multicomponent mixture flow, the vapour pressure of liquid at operating temperature (not entire mixture) is equal to the operating pressure.
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