Carnot Cycle – pV, Ts diagram
The Carnot cycle is often plotted on a pressure- volume diagram (pV diagram) and on a temperature-entropy diagram (Ts diagram).
When plotted on a pressure-volume diagram, the isothermal processes follow the isotherm lines for the gas, adiabatic processes move between isotherms and the area bounded by the complete cycle path represents the total work that can be done during one cycle.
The temperature-entropy diagram (Ts diagram) in which the thermodynamic state is specified by a point on a graph with specific entropy (s) as the horizontal axis and absolute temperature (T) as the vertical axis, is the best diagram to describe behaviour of a Carnot cycle.
It is a useful and common tool, particularly because it helps to visualize the heat transfer during a process. For reversible (ideal) processes, the area under the T-s curve of a process is the heat transferred to the system during that process.