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Engine Cycle Explorer

What you are seeing: the PV diagram of an ideal thermodynamic cycle. The animated point traces the cycle while a piston bar shows the volume; efficiency is read off the closed-loop area divided by the heat input. Carnot is the upper bound; Otto and Diesel are the spark-ignition and compression-ignition limits.

Figure 1. Four idealized engine cycles drawn on the PV plane.
compression r8.0
cutoff rc (Diesel)2.0
cycle

WHAT TO TRY

  • Raise the compression ratio r on the Otto cycle: the loop fattens, the shaded work area grows, and the efficiency bar climbs toward (but never reaches) the dashed Carnot line.
  • Switch cycles and watch the heat-addition step change shape: Otto adds heat at constant volume (vertical), Diesel at constant pressure (horizontal).
  • Compare Carnot and Stirling in the lower plot: both reversible cycles sit on the same ceiling, 1 − Tc/Th, for the same reservoirs.