$\frac{\left(T_{H}-T_{L}\right) \ln \frac{V_{2}}{V_{1}}}{T_{H} \ln \frac{V_{2}}{V_{1}}+\frac{3}{2}\left(T_{H}-T_{L}\right)} \text {, less than } e_{\text {Carnot }}$

$\frac{\left(T_{H}+T_{L}\right) \ln \frac{V_{2}}{V_{1}}}{T_{H} \ln \frac{V_{2}}{V_{1}}+\frac{3}{2}\left(T_{H}-T_{L}\right)} \text {, greater than } e_{\text {Carnot }}$

$\frac{\left(T_{H}-T_{L}\right) \ln \frac{V_{2}}{V_{1}}}{T_{L} \ln \frac{V_{2}}{V_{1}}+\frac{3}{2}\left(T_{H}-T_{L}\right)}, \text { greater than } e_{\text {Carnot }}$

$\frac{\left(T_{H}-T_{L}\right) \ln \frac{V_{2}}{V_{1}}}{T_{H} \ln \frac{V_{2}}{V_{1}}+\frac{3}{2}\left(T_{H}+T_{L}\right)}, \text { less than } e_{\text {Carnot }}$