Thermodynamics
COMPRESSION PROCESSES
Effects of Temperature Changes on Fluid Properties
An increase in temperature will tend to decrease the density of any fluid. If the fluid is confined
in a container of fixed volume, the effect of a temperature change will depend on whether the
fluid is compressible.
If the fluid is a gas, it will respond to a temperature change in a manner predicted by the ideal
gas laws. A 5% increase in absolute temperature will result in a 5% increase in the absolute
pressure.
If the fluid is an incompressible liquid in a closed container, an increase in the temperature will
have a tremendously greater and potentially catastrophic effect. As the fluid temperature
increases, it tries to expand, but expansion is prevented by the walls of the container. Because
the fluid is incompressible, this results in a tremendous increase in pressure for a relatively
minor temperature change. The change in specific volume for a given change in temperature
is not the same at various beginning temperatures. Resultant pressure changes will vary. A
useful thumb rule for water is that pressure in a water-solid system will increase about 100 psi
for every 1 °F increase in temperature.
Rev. 0
Page 101
HT-01
