Heat engine and Carnot limit: cycle and energy balance

The relationship to understand

ηCarnot=1−Tcold/Thot, W=ηQhot, Qrejected=Qhot−W; absolute temperatures in kelvins.

Try it and interpret

Between 400 °C and 20 °C, the reversible limit is about 56.5%. For 1000 J of heat received, it allows about 564.5 J of work. Follow the four stages on the temperature–entropy diagram.

Assumptions and limitations

Cyclic engine between two thermal reservoirs. The animated T–S cycle is the ideal reference; it does not become the actual cycle when a lower efficiency is selected. The rectangle area gives the maximum work, not the arbitrarily selected work output.

Go further with the course

This page focuses on one concept. The full chapter (French) contains the reasoning, further examples, slides and FAQ. Demonstration values are computed or constructed within the stated model; they are not new research findings.