This page is a single P–V canvas with a dropdown to load Carnot, Otto, Diesel, Stirling, or a Rankine P–v sketch. Gas cycles reuse the same closed-form geometry as the dedicated labs: nR = 1, γ = 1.4, Carnot/Stirling isotherms in kelvin, Otto/Diesel air-standard legs. Rankine replays the qualitative four-corner loop from the Rankine simulator (normalized ṕ sliders and turbine quality x₄), not steam-table volumes. The plot auto-scales axes to the active cycle so each loop is readable; numeric P and V are not a universal calibration across cycle types. Displayed η matches textbook formulas for the gas cycles; for Rankine it is a rough area-based proxy for teaching only.
Who it's for: Students who have met individual cycle pages and want side-by-side shape comparison without juggling browser tabs.
Key terms
P–V diagram
Carnot cycle
Otto cycle
Diesel cycle
Stirling cycle
Rankine cycle
thermal efficiency
auto-scale axes
How it works
Switch among Carnot, Otto, Diesel, Stirling, and a Rankine P–v sketch on one canvas. Four colors trace the loop in parametric order (0–25%, 25–50%, …); the physical meaning of each segment depends on the cycle (e.g. Carnot starts on the hot isotherm, not compression). Gas cycles match the standalone labs (nR = 1, γ = 1.4); Rankine is a qualitative sketch.
Frequently asked questions
Why do the axis numbers jump when I change cycles?
Each cycle is drawn in its own natural model units with automatic padding. The goal is to compare shapes and process labels (colored legs), not to read one universal pressure-volume scale across engines.
Is Rankine here as accurate as the full Rankine page?
No. Only the P–v cartoon is shared; the T–s dome and enthalpy-based discussion stay on the Rankine lab. Efficiency on this page is an illustrative ratio, not a plant heat balance.
Does Stirling really reach Carnot efficiency?
The ideal Stirling with a perfect regenerator and reversible isothermal/isochoric legs has the same efficiency limit as Carnot between the same reservoirs. Real machines have losses and imperfect regeneration.