This Demonstration models a Carnot cycle as either a heat engine or a heat pump. Change the temperature differences between the reservoirs and the Carnot cycle with sliders. The entropy changes for the reservoirs (
) and the overall entropy change
are calculated. When the temperature differences between the reservoirs and the engine/pump are zero, the total entropy change is zero and the process is reversible. The entropy change of the engine/pump, which is at steady state, is zero. All energies and entropy changes are per unit time, since these are continuous processes, but the time scale is arbitrary. The cycle efficiency
is calculated for the heat engine, and the coefficient of performance
is calculated for the heat pump. As the temperature differences between the reservoirs and the engine/pump increase, the efficiency/coefficient of performance decreases. For the heat engine,
is held constant at 1250 J, and for the heat pump,
is held constant at 600 J.