Thermal Efficiency of Reversible Power Cycles

Thermal efficiency of reversible power cycles working between given hot and cold reservoirs, i.e., Carnot efficiency

\(\displaystyle \eta = \frac{W_R}{Q_H} = \frac{Q_H - Q_C}{Q_H} = \frac{T_H - T_C}{T_H} = 1 - \frac{T_C}{T_H}\)

Symbols

\(\eta\) — thermal efficiency of reversible power cycle
\(Q_H\) — heat absorption from hot reservoir
\(Q_C\) — heat rejection to cold reservoir
\(W_R\) — work output of reversible power cycle
\(T_H\) — thermodynamic temperature of the hot reservoir
\(T_C\) — thermodynamic temperature of the cold reservoir

Schematic

Inputs & Outputs

\(T_C\) — cold reservoir temperature (K)

\(T_H\) — hot reservoir temperature (K)

η (-)

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Plot

The plot shows η vs T_H for different T_C values. The red dot marks the current operating point for the input T_C value's curve — drag it or use the T_H slider above to see how η changes as T_H changes at the current input T_C value.