When a substance exists as part liquid
and part vapor at saturation conditions, its quality (x) is defined as the ratio of the mass of the
vapor to the total mass of both vapor and liquid.
Saturday, May 3, 2014
Subcooled Liquid or Compressed Liquid
If the temperature of the liquid is
lower than the saturation temperature for the existing pressure,it is called either a subcooled liquid
(implying that the temperature is lower than the saturation temperature for the given pressure) or
a compressed liquid (implying that the pressure is greater than the saturation pressure for the
given temperature).
Moisture
The moisture content of a substance is
the opposite of its quality. Moisture (M) is defined as the ratio of the mass of the liquid to
the total mass of both liquid and vapor.
Saturated Vapor and Superheated Vapor
If a substance exists entirely as vapor
at saturation temperature, it is called saturated vapor.
When the vapor is at a temperature
greater than the saturation temperature, it is said to exist as superheated vapor.
Property Diagrams
Property Diagrams: The phases of a
substance and the relationships between its properties are most
commonly shown on property diagrams. There are six different types of
commonly encountered property diagrams. These are: Pressure-
Temperature (P-T) diagrams, Pressure-Specific Volume (P-ν) diagrams,
Pressure-Enthalpy (P-h) diagrams, Enthalpy-Temperature (h-T)
diagrams, Temperature-entropy (T-s) diagrams, and Enthalpy-Entropy
(h-s) or Mollier diagrams.
Mollier diagram
The Mollier diagram can be used to
determine various properties of a fluid.
Mollier
diagram is an h versus s plot.
Can only be used when quality is
greater than 50% and for superheated steam.
Contains a series of constant
temperature, constant pressure, constant moisture content, and
constant superheat lines.
Triple Point & Critical Point
The point where the three lines(sublimation, fusion and vaporization line) meet is
called the triple point. The triple point is the only point at which
all three phases can exist in equilibrium.
The point where the vaporization line
ends is called the critical point.
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