Injector Deposits and Emissions in Internal Combustion Engines

Injector deposits arise from incomplete combustion, thermal cracking and interactions of fuel components under high temperature and pressure within internal combustion engines. These accumulations form on injector nozzles, combustion chamber walls and injector tips, leading to altered spray patterns, degraded atomisation and disrupted fuel–air mixing. Deposit chemistry ranges from organic residues such as polycyclic aromatic hydrocarbons to inorganic salts, often exhibiting stratified, multilayer structures that reflect cyclical ageing. Key drivers include fuel composition, injection timing, pressure transients and ambient conditions. The presence of deposits accelerates mechanical wear, increases hydrocarbon, particulate and nitrogen oxide emissions, and undermines fuel economy. In response to tightening emissions legislation and the adoption of diverse fuel blends, research has intensified on deposit mitigation. Strategies under investigation encompass tailored detergent–dispersing additives, refined fuel specifications, modified injector geometries and real-time monitoring techniques. Advances in molecular‐scale characterisation now inform the design of next-generation engines and fuels that reconcile performance, durability and environmental stewardship.

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Injector Deposits and Emissions in Internal Combustion Engines publication trend

The graph below shows the total number of articles in injector deposits and emissions in internal combustion engines across all publications each year (not limited to Nature Index journals).

Technical terms

Fuel injector deposits: Accumulations of organic and inorganic materials on injector surfaces that disrupt spray patterns and fuel–air mixing.

Fuel film: Liquids adhering to the nozzle surface after injection, leading to uneven atomisation and increased emissions.

Polycyclic aromatic hydrocarbons (PAHs): Organic compounds with fused aromatic rings, often formed through combustion reactions and contributing to particulate matter.

Detergent–dispersing additives (DDAs): Chemical agents blended into fuel to inhibit deposit formation and maintain injector cleanliness.

3D OrbiSIMS: Three-dimensional Orbitrap secondary ion mass spectrometry, a high-resolution technique for spatially resolved molecular analysis of deposits.

References

1. Spatially Resolved Molecular Compositions of Insoluble Multilayer Deposits Responsible for Increased Pollution from Internal Combustion Engines. ACS Applied Materials & Interfaces (2020).
2. Time resolved growth of (N)-polycyclic aromatic hydrocarbons in engine deposits uncovered with OrbiSIMS depth profiling. Analyst (2022).
3. Quantitative characterisations of spray deposited liquid films and post-injection discharge on diesel injectors. Fuel (2021).
4. The impact of alcohol admixture with gasoline on carbon build-up and fuel injectors performance. Eksploatacja i Niezawodnosc - Maintenance and Reliability (2022).
5. Investigation into the Impact of the Composition of Ethanol Fuel Deposit Control Additives on Their Effectiveness. Energies (2021).