The Carnot Cycle - explore

Overview

This T-S diagram, a plot of temperature (T) versus entropy (S), illustrates the Carnot cycle, a theoretical thermodynamic cycle that describes the most efficient possible engine operating between two temperature reservoirs. The cycle consists of four reversible processes that return the system to its initial state. The area enclosed by the cycle on a T-S diagram represents the net work done by the engine.

Isothermal Expansion (A to B)

The cycle begins at point A. From A to B, the working fluid undergoes a reversible isothermal expansion at a constant high temperature, TH. During this process, the engine absorbs heat, QH, from the hot reservoir. The entropy of the system increases as heat is added.

Adiabatic Expansion (B to C)

Following the isothermal expansion, from B to C, the working fluid undergoes a reversible adiabatic expansion. No heat is exchanged with the surroundings, and the temperature of the fluid decreases from TH to a lower temperature, TL. The entropy of the system remains constant during this process, as indicated by the vertical line.

Isothermal Compression (C to D)

At point C, the fluid undergoes a reversible isothermal compression at the constant lower temperature, TL, moving to point D. During this step, heat, QL, is rejected from the engine to the lower temperature reservoir. The entropy of the system decreases as heat is removed.

Adiabatic Compression (D to A)

Finally, from D back to A, the working fluid undergoes a reversible adiabatic compression. No heat is exchanged, and the temperature of the fluid increases from TL back to the initial high temperature, TH. The entropy of the system remains constant, completing the cycle.