Thermodynamics
Otto Cycle Simulator
Examine the thermodynamics of a four-stroke spark-ignition internal combustion engine. Tune variables to explore compression ratios, heat inputs, and peak pressures on an interactive PV cycle.
Cycle Type
Otto (4-Stroke)
Spark Ignition
Working Fluid
Ideal Air
k = 1.4
Output
CSV
Export ready
Parameters
Engine Preset
Animated engine cycle
Thermodynamic Governing Relations
Thermal Efficiency
η = 1 - 1 / r^(γ-1)
State 2 Temp (K)
T2 = T1 * r^(γ-1)
State 3 Temp (K)
T3 = T2 + Qin / Cv
Net Work Output
Wnet = η * Qin
Mean Effective Pressure
MEP = Wnet / (v1 - v2)
The cycle uses air-standard assumptions with constant specific heat values: Cv = 0.718 kJ/kg·K and γ = 1.4.
State 3 represents the peak combustion condition with a maximum pressure of 52.2 bar.
State 4 represents the exhaust condition at 2.6 bar prior to heat rejection.
Linked Engine Mechanics
Stroke: 1. Intake StrokeCrank: 0°
Thermal Efficiency
57.5%
Net Work Output
460kJ/kg
Mean Eff. Pressure
6.14bar
Peak Temperature
1820K
Pressure-Volume (P-V) Diagram
State Profile Nodes
| Spec. Volume (m³/kg) | P Comp (bar) | P Exp (bar) | T Comp (K) | T Exp (K) |
|---|---|---|---|---|
| 0.1000 | 20.27 | 52.25 | 706 | 1820 |
| 0.1625 | 10.27 | 26.48 | 581 | 1499 |
| 0.2250 | 6.51 | 16.79 | 511 | 1316 |
| 0.2875 | 4.62 | 11.91 | 463 | 1193 |
| 0.3500 | 3.51 | 9.04 | 428 | 1103 |
| 0.4125 | 2.79 | 7.19 | 401 | 1033 |
| 0.4750 | 2.29 | 5.90 | 379 | 976 |
| 0.5375 | 1.92 | 4.96 | 360 | 929 |
| 0.6000 | 1.65 | 4.25 | 345 | 889 |
| 0.6625 | 1.44 | 3.70 | 331 | 854 |
| 0.7250 | 1.27 | 3.26 | 320 | 824 |
| 0.7875 | 1.13 | 2.91 | 309 | 797 |
| 0.8500 | 1.01 | 2.61 | 300 | 773 |