In this screencase I'm going to briefly describe the interactive simulation that represents
the Rankine cycle for generating power from steam.
It has several options but we're plotting a pressure/ enthalpy diagram for the cycle
where at point 1 we have high pressure liquid that we, at constant pressure, feed into a
boiler.
Raise it to its boiling temperature at point 2 in the boiler and then evaporate all the
liquid and then super-heat it so that leaving the boiler is steam, super-heated steam, at
point 3.
Then we feed this steam to a steam turbine which generates work and lowers both the pressure
and the temperature, so the enthalpy decreases.
And we may end up with super-heated steam or we may end up with saturated steam or steam
with quality, depending on the turbine efficiency, and that's one of the sliders that we can
change in the simulation.
We can also change the outlet pressure as well as the inlet pressure.
Once we leave the turbine then we condense the steam back to a liquid so we have saturated
liquid at point 5.
We can pressurize this back up to high pressure this back up to high pressure to complete
the cycle.
So this is a brief description, now let's look at the actual simulation.
So here's the simulation on the Wolfram site.
And first it's showing the pressure enthlpy diagram where we can change the inlet pressure.
This is the inlet pressure to the turbine.
As we raise the pressure of course we are coming in with steam that has higher pressure,
higher enthalpy.
We can also change the outlet pressure, and if we raise the outlet pressure we are going
to have a smaller pressure drop, we are going to end up getting less work out of the process.
And then we can change the efficiency.
So this is the efficiency relative to reversible process.
So this dotted line, starting at point 3 corresponds to reversible.
So if I make the efficiency 0.95 then we are close to reversible, so this is efficiency
that is a fraction of the reversible efficiency.
How close we can approach a reversible process.
So if I lower the efficiency then we are going to get less work out of the turbine.
Other options here, we are going to look at the cycle.
Where for the conditions we've chosen, we have super-heated vapor leaving the turbine
and then saturated liquid that is fed to the pump, where we have high pressure of liquid,
we've evaporated so that super-heated vapor is what we feed to the turbine.
And then what we also have as part of the simulation, the conditions.
So as we change the pressure here we are changing the inlet pressure.
And that of course changes how much work as we go to higher pressure we get more work
out of the turbine.
Likewise if we go to higher efficiency we get more work out of the turbine.
And higher efficiencies then we have a lower temperature leaving the turbine.
So you can use these sliders to get a better understanding of the Rankine cycle which is
the simplest version of a cycle used to create work from some high temperatures or such as
burning natural gas to heat the steam.
And of course in this cycle we need some way to now condense the low pressure steam, such
as a large body of water for example.