Home

Steam Properties - Limitations, Inaccuracies and Restrictions.

Definition

My steam property simulator should be employed for pedagogical purposes only.

Where it occurs

The diagram is used to design steam driven power cycles. (A modified version is provided elsewhere for air conditioning.)

Special features

-

How to draw it

Left click in the plot area to explore the thermodynamic properties for a particular (s,T) coordinate. You can plot curves of constant pressure, temperature or entropy through this point of interest (POI). The POI can also be specified with the "number input (PTx)" button. Provide two values to complete the set {pressure, temperature, quality}, and type -1 for the third, unknown value.

Restrictions, limitations and innaccuracy.

The simulation is provided for pedagogical purposes only. It should not be employed in formal design calculations, or for summative college assessments. No attempt is made to evaluate properties for pressures greater than 300 bar; where deemed necessary the algorithm increases entropy above its input value and to the point where p=300bar. At present I am not fully happy about my intepretation of region 3 , described in the IAPWS documents below. In past versions the results have been erratic at certain points.

Twelve iterations of golden search are used. This adds an uncertainty of up to \(600/2^{12}=0.15\) K in temperature and up to \(9/2^{12}=0.002 kJ/kgK \) in entropy.

There is no option to change scales on the temperature and entropy axes: this limits the range of properties. Furthermore pressures are restricted to less than 300 bar.

The theory

NA

Exercises

NA

Links

IAWPS Revised release .

NIST tables .