Answer
See explanation
Work Step by Step
Allowing a temperature difference of $10^{\circ}C$ for effective heat transfer, the evaporation temperature of the refrigerant should be $-20^{\circ}C$. The saturation pressure corresponding to $-20^{\circ}C$ is $0.133\text{ MPa}$. Therefore, the recommended pressure would be $0.12\text{ MPa}$.
