Combustion Efficiency and Emission Control in Internal Combustion Engines
Summary
Combustion efficiency and emission control in internal combustion engines lie at the heart of efforts to reconcile performance, fuel economy and environmental impact. Optimising the conversion of chemical energy into mechanical work demands careful management of in-cylinder processes, including fuel injection timing, mixture formation and turbulence. Advances in combustion chamber design, high-pressure direct injection, variable valve timing and real-time control strategies have driven thermal efficiencies beyond 45 % in diesel engines and over 40 % in modern gasoline units. At the same time, stringent limits on nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO) and unburned hydrocarbons (HC) have spurred development of exhaust aftertreatment systems such as three-way catalysts, selective catalytic reduction (SCR) and particulate filters. Integration of exhaust gas recirculation (EGR) and water injection has further reduced peak combustion temperatures and suppressed NOx formation. Emerging approaches, including lean-burn combustion, homogeneous charge compression ignition (HCCI) and alternative fuel blends, promise additional gains in efficiency and lower carbon footprints. Numerical modelling, machine learning–based controls and holistic powertrain calibration are enabling ever more precise management of transient operation, while real-world driving emissions (RDE) protocols ensure that laboratory gains translate into tangible air-quality improvements. The global significance of this research spans passenger vehicles, heavy-duty transport, stationary power generation and non-road machinery, uniting fundamental thermochemistry with practical engineering to meet both climate and air-quality targets.
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Combustion Efficiency and Emission Control in Internal Combustion Engines publication trend
The graph below shows the total number of articles in combustion efficiency and emission control in internal combustion engines across all publications each year (not limited to Nature Index journals).
Technical terms
Combustion efficiency: Ratio of fuel energy converted into useful mechanical work within the engine cylinder.
Stoichiometry: Ideal air–fuel ratio at which complete combustion occurs without excess reactants.
Selective catalytic reduction (SCR): Aftertreatment technique that reduces NOx emissions by injecting a reductant (commonly urea) into the exhaust stream over a catalyst.
Exhaust gas recirculation (EGR): Process of recirculating a portion of exhaust gas back into the intake to lower peak combustion temperatures and reduce NOx formation.
Three-way catalyst: Catalytic converter that simultaneously oxidises hydrocarbons and carbon monoxide while reducing nitrogen oxides under stoichiometric conditions.
References
- Trends in Automotive Emission Legislation: Impact on LD Engine Development, Fuels, Lubricants and Test Methods: a Global View, with a Focus on WLTP and RDE Regulations. Emission Control Science and Technology (2019).
- A Numerical and Experimental Study of Marine Hydrogen–Natural Gas–Diesel Tri–Fuel Engines. Polish Maritime Research (2020).
- Reduction of the Gaseous Emissions in the Marine Diesel Engine Using Biodiesel Mixtures. Journal of Marine Science and Engineering (2020).
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