Solution:
A thermodynamic power cycle consists of four sequential thermodynamic process described as follows:
\begin{center}
\begin{tabular}{@{}cl@{}}
Process 1 : & isentropic compression from state $A$ to state $B$.\\
Process 2 : & isobaric heating from state $B$ to state $C$.\\
Process 3 : & isentropic expansion from state $C$ to state $D$.\\
Process 4 : & isochoric cooling (constant–volume) from state $D$ to state $A$.\\
\end{tabular}
\end{center}
\begin{parts}
\part [5] Please sketch this cycle on a $P-V$ diagram.
\part [15] If air is the working fluid of this power cycle and can be regarded as an ideal gas, please estimate the thermal efficiency ($\eta$) of this air–standard power cycle. Please express the thermal efficiency ($\eta$) in terms of $\gamma = C_P / C_V$, the compression ratio ($r = V_A / V_B$), the expansion ratio ($k = V_D / V_C$), and other proper thermodynamic variables.
\end{parts}
