Combustion Efficiency in Internal Combustion Engines
Summary
Combustion efficiency in internal combustion engines refers to the proportion of chemical energy in the fuel that is converted into useful mechanical work. Attaining high combustion efficiency is critical for reducing fuel consumption, lowering pollutant emissions and meeting increasingly stringent environmental regulations. In four-stroke and two-stroke architectures, the interplay between mixture formation, in-cylinder flow dynamics, ignition delay and heat release rate governs the completeness of fuel oxidation. Modern advances include optimised port and injector designs, advanced control of air–fuel stratification and the introduction of alternative combustion modes. Improvements in computational fluid dynamics and zero-dimensional modelling have accelerated the design of scavenging systems and chamber geometries that enhance turbulence and promote homogeneous charge formation. The global significance of this work lies in its capacity to deliver more efficient transport, power generation and off-road machinery while mitigating carbon dioxide and nitrogen oxide outputs.
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Combustion Efficiency in Internal Combustion Engines publication trend
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Technical terms
Combustion efficiency: The ratio of fuel energy converted into useful work, accounting for losses due to incomplete oxidation and heat transfer.
Scavenging efficiency: A measure of how effectively exhaust gases are expelled and fresh charge is introduced during the scavenging phase.
Homogeneous Charge Compression Ignition (HCCI): A low-temperature combustion mode in which a premixed air–fuel charge auto-ignites uniformly, yielding low NOx and soot.
Brake thermal efficiency: The fraction of fuel energy that is converted into brake power at the crankshaft, indicating overall engine efficiency.
Indicated mean effective pressure (IMEP): An average pressure derived from the indicated work per cycle, used as an objective function for performance optimisation.
References
- Parameter Optimization on the Uniflow Scavenging System of an OP2S-GDI Engine Based on Indicated Mean Effective Pressure (IMEP). Energies (2017).
- CAI combustion of gasoline and its mixture with ethanol in a 2-stroke poppet valve DI gasoline engine. Fuel (2013).
- A High-Efficiency Two-Stroke Engine Concept: The Boosted Uniflow Scavenged Direct-Injection Gasoline (BUSDIG) Engine with Air Hybrid Operation. Engineering (2019).
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