Chapter 15, Problem 32PE

Practical steam engines utilize $\text{45}0°\text{C}$ steam, which is later exhausted at $\text{27}0°\text{C}$. (a) What is the maximum eficiency that such a heat engine can have? (b) Since $\text{27}0°\text{C}$ steam is still quite hot, at second steam engine is sometimes operated using the exhaust of the first. What is the maximum eficiency of the second engine if its exhaust has a temperature of $\text{15}0°\text{C}$ ? (c) What is the overall eficiency of the two engines? (d) Show that this is the same eficiency as a single Carnot engine operating between $\text{45}0°\text{C}$ and $\text{15}0°\text{C}$. Explicitly show how you follow the steps in the Problem-Solving Strategies for Thermodynamics.