Steam Properties

Property Diagrams

Here are some diagrams generated by the freesteam IAPWS-IF97 steam properties library, which show the location of the saturation regions for steam when plotted against various properties. I found these very useful when writing the 'whichRegion' routines for the general-purpose two-way property solvers in freesteam.

You can easily reproduce these plots from freesteam if you use the diagram.cli program which can be generated from diagram.cli.cpp in the cli directory of the freesteam source code distribution. This output of this program is a Matlab m-file which you can run. For example,

cd cli
make diagram.cli
./diagram.cli Ts > Ts.m

Then, in Matlab, run the Ts.m m-file and you will see a T-s diagram similar to that shown below. If viewing on screen, it is recommended that you use the colordef black command before you run the M-file.

For all these plots, pressure is in MPa, temperature is in Kelvin, specific enthalpy and internal energy are in kJ/kg and specific entropy is in kJ/kgK. In some cases you will notice that lines don't meet up; mostly this is due to linearly-space values being plotted on logarithmic curves, and is something we will need to fix in a future version.

T-s: Temperature versus specific entropy

T-s diagram

T-h: Temperature versus specific enthalpy

T-h diagram

T-v: Temperature versus specific volume

T-v diagram

T-p: Temperature versus pressure

T-p diagram

p-h: Pressure versus specific enthalpy

p-h diagram

p-u: Pressure versus specific internal energy

p-u diagram

p-s: Temperature versus specific entropy

p-s diagram

v-u: Specific volume version specific internal energy

v-u diagram

John Pye
Last modified: 25 Feb 2013