Thermodynamics
Otto Cycle Simulator
Simulate the Otto Cycle engine process. Adjust compression ratio, specific heat, and heat input to analyze thermodynamic state limits, work output, and thermal efficiency.
Cycle Type
Otto (Gasoline)
Idealized 4-stroke
State Solver
Closed system
Air-standard basis
Output
CSV
Export ready
Parameters
Working Fluid Preset
Animated cycle sweep
Thermodynamic Cycle Equations
Otto Efficiency
η = 1 - (1 / r^(γ-1))
Peak Temperature (T3)
T3 = T2 + Qin/Cv
Net Work Output
W_net = Qin - Qout = Cv·(T3 - T4 - T2 + T1)
The ideal Otto Cycle models gasoline spark-ignition engines using four internally reversible steps.
Efficiency depends strictly on the compression ratio (r) and the specific heat ratio (γ) of the gas.
High compression ratios improve efficiency but are limited by fuel knocking (auto-ignition limits).
Piston Stroke & P-V Diagram
Thermal Efficiency
56.5%
Net Work Done
847.1kJ/kg
Max Temperature (T3)
2780K
Heat Rejected (Qout)
652.9kJ/kg
Efficiency vs Compression Ratio
Efficiency Sweep Data
| Compression Ratio (r) | Thermal Efficiency (%) |
|---|---|
| 4.0 | 42.6 |
| 5.0 | 47.5 |
| 6.0 | 51.2 |
| 7.0 | 54.1 |
| 8.0 | 56.5 |
| 9.0 | 58.5 |
| 10.0 | 60.2 |
| 11.0 | 61.7 |
| 12.0 | 63.0 |
| 13.0 | 64.2 |
| 14.0 | 65.2 |
| 15.0 | 66.2 |
| 16.0 | 67.0 |
| 17.0 | 67.8 |
| 18.0 | 68.5 |
| 19.0 | 69.2 |
| 20.0 | 69.8 |