Thermodynamic cycle of a petrol (gasoline) engine On which idealized thermodynamic cycle is a conventional spark-ignition petrol engine modeled for analysis and instruction?

Introduction / Context:
Ideal cycles provide a simplified framework to analyze engine performance. Spark-ignition petrol engines are classically associated with the constant-volume heat-addition Otto cycle.

Given Data / Assumptions:

• Four-stroke spark-ignition engine with near-stoichiometric fueling.
• Ideal analysis (no pumping, friction, heat losses).
• Constant-volume heat addition approximation during combustion.

Concept / Approach:
The Otto cycle consists of isentropic compression, constant-volume heat addition, isentropic expansion, and constant-volume heat rejection. This approximates combustion that occurs quickly near top dead center in SI engines.

Step-by-Step Solution:

Verification / Alternative check:
Textbooks and engine courses consistently pair petrol engines with the Otto cycle in idealized analyses.

Why Other Options Are Wrong:

• Carnot: theoretical maximum efficiency, not a practical engine cycle.
• Diesel: constant-pressure addition fits CI engines.
• Rankine: steam power plants.
• Miller: a valve-timing-modified variant; not the baseline teaching cycle.

Common Pitfalls:
Assuming real combustion exactly matches constant volume; in practice, it is neither perfectly constant-volume nor instantaneous.

Final Answer: