The best possible turbine would operate without any internal irreversibilities:

• no heat transfer down temperature gradients within the device
• no un-restrained expansion within the device
• no friction within the device
• no electrical resistance within the device

Suppose a turbine with the above properties accepts superheated water vapour at $10\,\text{MPa}$, ${410}\,^\circ\text{C}$. If the outlet pressure is $100\,\text{kPa}$, what is

1. the vapour quality $x$ at the turbine outlet?
2. the specific work output, $w = \dot{W}_\text{out}/\dot{m}$?

Answers:

1. $x =$ (answer tolerance: $0.005$)
2. $w =$ $\text{kJ/kg}$ (answer tolerance: $0.5\,\text{kJ/kg}$)