Answer
See explanation
Work Step by Step
The reversed Stirling cycle is identical to the Stirling cycle, except it operates in the reversed direction. Remembering that the Stirling cycle is a totally reversible cycle, the reversed Stirling cycle is also totally reversible, and thus its COP is
$$
\mathrm{COP}_{\mathrm{R}, \text { Stirling }}=\frac{1}{T_H / T_L-1}
$$
