Halliday, Resnick & Walker — Entropy and the Second Law of Thermodynamics: Problem 73

Stirling engine. Figure 20.2.6 is a p-V diagram for an idealized version of a small Stirling engine, named for Reverend Robert Stirling of the Church of Scotland, who proposed the scheme in 1816. The engine uses \( n = 8.1 \times 10^{-3} \) mol of an ideal gas, operates between hot and cold heat reservoirs of temperatures \( T_H = 95^\circ C \) and \( T_L = 24^\circ C \), and runs at the rate of \( 0.70 \) cycle per second. A cycle consists of an isothermal expansion (\( ab \), from \( V_a \) to \( 1.5V_a \)), an isothermal compression (\( cd \)), and two constant-volume processes (\( bc \) and \( da \)). (a) What is the engine’s net work per cycle? (b) What is the power of the engine? (c) What is the net heat transfer into the gas during a cycle? (d) What is the efficiency \( \varepsilon \) of the engine?