Thermodynamics
PROPERTY DIAGRAMS AND STEAM TABLES
PROPERTY DIAGRAMS AND STEAM TABLES
Property diagrams and steam tables are used in studying the theoretical and
actual properties and efficiencies of a given system.
EO 1.16
Given a Mollier diagram and sufficient information to
indicate the state of the fluid, DETERMINE any
unknown properties for the fluid.
EO 1.17
Given a set of steam tables and sufficient information
to indicate the state of the fluid, DETERMINE any
unknown properties for the fluid.
EO 1.18
DETERMINE the change in the enthalpy of a fluid as
it passes through a system component, given the state
of the fluid at the inlet and outlet of the component
and either steam tables or a Mollier diagram.
Property Diagrams
The phases of a substance and the relationships between its properties are most commonly shown
on property diagrams. A large number of different properties have been defined, and there are
some dependencies between properties. For example, at standard atmospheric pressure and
temperature above 212°F, water exists as steam and not a liquid; it exists as a liquid at
temperatures between 32°F and 212°F; and, it exists as ice at temperatures below 32°F. In
addition, the properties of ice, water, and steam are related. Saturated steam at 212°F and
standard atmospheric pressure has a specific volume of 26.8 ft3/lbm. At any other temperature
and pressure, saturated steam has a different specific volume. For example, at 544°F and 1000
psia pressure, its specific volume is 0.488 ft3/lbm.
There are five basic properties of a substance that are usually shown on property diagrams.
These are: pressure (P), temperature (T), specific volume (n), specific enthalpy (h), and specific
entropy (s). When a mixture of two phases, such as water and steam, is involved, a sixth
property, quality (x), is also used.
There are six different types of commonly encountered property diagrams. These are: Pressure-
Temperature (P-T) diagrams, Pressure-Specific Volume (P-n) diagrams, Pressure-Enthalpy (P-h)
diagrams, Enthalpy-Temperature (h-T) diagrams, Temperature-entropy (T-s) diagrams, and
Enthalpy-Entropy (h-s) or Mollier diagrams.
Rev. 0
Page 41
HT-01
