Randall D. Knight — Heat Engines and Refrigerators: Problem 61

FIGURE P21.61 is the $pV$ diagram of Example 21.2, but now the device is operated in reverse. (a) During which processes is heat transferred into the gas? (b) Is this $Q_H$, heat extracted from a hot reservoir, or $Q_C$, heat extracted from a cold reservoir? Explain. (c) Determine the values of $Q_H$ and $Q_C$. Hint: The calculations have been done in Example 21.2 and do not need to be repeated. Instead, you need to determine which processes now contribute to $Q_H$ and which to $Q_C$. (d) Is the area inside the curve $W_{in}$ or $W_{out}$? What is its value? (e) The device is now being operated in a ccw cycle. Is it a refrigerator? Explain.