Thermal Efficiency

Definition: Thermal Efficiency

The thermal efficiency of a heat engine is the ratio of the work $W$ done by the engine and the heat $Q_{\text{H}}$ which it absorbs:

$$\frac{W}{Q_H}$$

NOTATION

$$\eta$$

NOTE

The thermal efficiency can be equivalently expressed via the heat $Q_{\text{H}}$ that the engine absorbs and the heat $Q_{\text{C}}$ which it releases:

$$\eta =1+\frac{Q_{\text{H}}}{Q_{\text{C}}}=1-\left|\frac{Q_{\text{C}}}{Q_{\text{H}}}\right|$$