Isentropic (steam)
Definition
... a process at constant entropy, denoted by a vertical line on a Ts diagram.
Where it occurs.
An ideal, reversible expansion (in a turbine) occurs isentropically. The theoretical Carnot Cycles includes isentropic compression.
Special features
There is no heat addition (adiabatic) and no gas friction. An isentropic process is said to be "reversible".
How to draw it
Locate the POI and press the isentropic button.
The theory
With regards to steam properties, see
page on the steam POI.
Exercises
Click on the graph to get a POI with \(s \approx 6 kJ/kg K \) (any temperature) and plot an isentropic line through it. Start at the bottom of the line (T=275 K) and continuously click along the line to get new POIs. Note (1) we start with wet steam with dryness fraction of 68% and IAWPS region 4. Moving the POI upwards increases the pressure and dryness fraction, in addition to temperature. At the saturated steam point (g-curve, \( T \approx 530 K \) ) dryness reaches 100%. Thereafter pressure continues but the IAWPS region is region 2. The maximum achievable pressure of 350 bar is found near the top of the plot.
Links
... to follow.