Effects of Combustion-Chamber Deposits on Octane Requirement and Engine Power Output

Duckworth, J. B.

doi:10.4271/510210

Cited by 9 publications

(1 citation statement)

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“…17 Because the phasing of combustion in an SI engine can be prescribed by the spark event, the effects from deposits only assert themselves at a small subset of operating conditions near the knocking limit, often referred to as octane requirement increase (ORI). 18–23 Although it primarily influences SI engine operation at the extremes of the operating map, deposit growth in SI engines has a non-negligible impact on a number of performance parameters such as power, fuel economy, and emissions. 20,24–32 However, because HCCI engine operation does not have a direct trigger, the presence of deposits will affect the entire operating range.…”

Section: Introductionmentioning

confidence: 99%

The effect of fuel composition and additive packages on deposit properties and homogeneous charge compression ignition combustion

Lacey

Kameshwaran

Filipi

et al. 2019

International Journal of Engine Research

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Homogeneous charge compression ignition combustion is highly dependent on in-cylinder thermal conditions that are favorable to auto-ignition, and the presence of deposits can dramatically impact the in-cylinder environment. Because fuels available at the pump can differ considerably in composition, and fuel composition and the included additive package directly affect how deposits accumulate in a homogeneous charge compression ignition engine, strategies intended to bring homogeneous charge compression ignition to market must account for this fuel and additive variability. In order to investigate this impact, two oxygenated refinery stream test fuels with two different additives were run in a single cylinder homogeneous charge compression ignition engine. The two fuels had varying chemical composition; one represents a “dirty” fuel with high aromatic content that was intended to simulate a worst-case scenario for deposit growth, while the other represents a California Reformulated Gasoline Blendstock for Oxygenate Blending fuel, which is the primary constituent of pump gasoline at fueling stations across the state of California. The additive packages are typical of technologies that are commercially available to treat engine deposits. Both fuels were run in an experimental, single-cylinder homogeneous charge compression ignition engine in a passive conditioning study, during which the engine was run at steady state over a period of time in order to track changes in the homogeneous charge compression ignition combustion event as deposits accumulated in-cylinder. Both the composition and the additive influenced the structure of the combustion chamber deposit layer, but more importantly, both the rate at which the layer developed and the equilibrium thickness it achieved. The overall thickness of the combustion chamber deposit layer was found to have a significant impact on homogeneous charge compression ignition combustion phasing.

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