Question

A steam turbine operates at a boiler temperature of 450 k and an exhaust temperature of 300 k. what is the maximum theoretical efficiency of this system?

Answer 1

The maximum theoretical efficiency of the system is the one corresponding to the efficiency of a Carnot cycle operating between the same temperatures of the system:
$\eta=1- \frac{T_c}{T_h}$
where $T_c$ and $T_h$ are the cold and hot temperatures, respectively.
In our problem, $T_c=300 K$ and $T_h=450 K$, therefore the maximum theoretical efficiency is
$\eta=1- \frac{300 K}{450 K}=0.33$
So, 33%.