Effect of In-Cylinder Liquid Fuel Films on Engine-Out Unburned Hydrocarbon Emissions for an SI Engine

Costanzo, Vincent; Heywood, John B.

doi:10.4271/2012-01-1712

Cited by 18 publications

(7 citation statements)

References 14 publications

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“…Indeed, "pool fires" from these films have been reported [11][12][13]. A movie frame sequence showing the "pool fire" development from a liquid fuel film deliberately deposited on the piston [13,15] is shown in Fig. 15.…”

Section: A Conceptual Model For Particulate Formationmentioning

confidence: 99%

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On the Nature of Particulate Emissions from DISI Engines at Cold-Fast-Idle

Ketterer¹,

Cheng²

2014

SAE Int. J. Engines

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Particulate emissions from a production gasoline direct injection spark ignition engine were studied under a typical cold-fast-idle condition (1200 rpm, 2 bar NIMEP). The particle number (PN) density in the 22 to 365 nm range was measured as a function of the injection timing with single pulse injection and with split injection. Very low PN emissions were observed when injection took place in the mid intake stroke because of the fast fuel evaporation and mixing processes which were facilitated by the high turbulent kinetic energy created by the intake charge motion. Under these conditions, substantial liquid fuel film formation on the combustion chamber surfaces was avoided. PN emissions increased when injection took place in the compression stroke, and increased substantially when the fuel spray hit the piston. A conceptual model was established for the particulate matter (PM) formation process in which PM is formed by pyrolysis after the normal premixed flame passage in fuel rich plumes originating from liquid films on the cylinder walls. The pyrolysis process is supported by heat conducted from the hot burned gases outside the plume and by the energy released by the pyrolysis reactions. Thus, the "pool fire" often observed is not a diffusion flame since the small amount of residual oxygen in the burned gases cannot support such a flame. The luminosity is radiation from the hot soot particles which are not oxidized after being formed in the pyrolysis reactions. This model was supported by the PN data obtained from sweeping the charge equivalence ratio from lean to rich.

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Section: A Conceptual Model For Particulate Formationmentioning

confidence: 99%

“…The fuel vapor that emerges from the fuel films produces fuel rich regions which are responsible for PM formation. Visible soot particle radiation, often referred to as "pool fires", has been observed [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

On the Nature of Particulate Emissions from DISI Engines at Cold-Fast-Idle

Ketterer¹,

Cheng²

2014

SAE Int. J. Engines

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“…The thickness of the adhered fuel film [6], the adhered fuel mass ratio [7], and the distribution of liquid fuel and vapor [8] after impingement were measured using the visualization method in previous works. In addition, the influences of injection pressure [9], injection duration [6], injection angle [10,11], wall temperature [12,13], air flow [12], and injector configuration [14] were discussed in detail.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional numerical investigation on wall film formation and evaporation in port fuel injection engines

Liu

Yan

Jia

et al. 2016

Numerical Heat Transfer, Part A: Applications

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Wall film formation and evaporation were studied on a flat wall inside a constant-volume vessel using a three-dimensional numerical method. The computation was based on the discrete phase model (DPM) of spray dispersion, a spray-wall interaction model coupled with an enhanced wall film evaporation sub-model, in which the operating conditions of cold wall are considered for port fuel injection (PFI) engines. The influence of impacting parameters including injection pressure, the impingement distance from the injector and the impinged wall, injection duration, impingement angle, and wall temperature was discussed. ARTICLE HISTORY

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“…During the cold crank-start of GDI engines, the significant overfueling necessary to form a combustible mixture results in the formation of fuel films. The liquid fuel films become a dominant source for HC emissions, comparable to or greater than the crevice storage mechanism [7]. Higher burned gas temperatures in the expansion process with retarded timing promotes both the evaporation and oxidation of the HC contained in the fuel films.…”

Section: Combustion Phasing Effectmentioning

confidence: 99%

“…Because of the large amount of fuel injected, a significant portion of the injected fuel lands on the cold combustion chamber surfaces, resulting in fuel films that fail to evaporate before combustion. Optical investigations conducted by Costanzo et al [7] provide evidence of the significant role that these fuel films play on HC emissions and PM formation. Additionally, the low temperature impacts negatively the classical HC emissions mechanisms identified by Cheng et al [8]; low temperature results in larger crevice volumes, increases the solubility of hydrocarbons into the lubricant oil layer, and intensifies the heat transfer rates from the hot gases into the cylinder walls.…”

Section: Introductionmentioning

confidence: 99%

Cycle-by-Cycle Analysis of Cold Crank-Start in a GDI Engine

Rodriguez¹,

Cheng²

2016

SAE Int. J. Engines

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The first 3 cycles in the cold crank-start process at 20°C are studied in a GDI engine. The focus is on the dependence of the HC and PM/PN emissions of each cycle on the injection strategy and combustion phasing of the current and previous cycles. The PM/PN emissions per cycle decrease by more than an order of magnitude as the crank-start progresses from the 1 st to the 3 rd cycle, while the HC emissions stay relatively constant. The wall heat transfer, as controlled by the combustion phasing, during the previous cycles has a more significant influence on the mixture formation process for the current cycle than the amount of residual fuel. The results show that the rise in HC emissions caused by the injection spray interacting with the intake valves and piston crown is reduced as the cranking process progresses. Combustion phasing retard significantly reduces the PM emission. The HC emissions, however, are relatively not sensitive to combustion phasing in the range of interest.

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Effect of In-Cylinder Liquid Fuel Films on Engine-Out Unburned Hydrocarbon Emissions for an SI Engine

Cited by 18 publications

References 14 publications

On the Nature of Particulate Emissions from DISI Engines at Cold-Fast-Idle

On the Nature of Particulate Emissions from DISI Engines at Cold-Fast-Idle

Three-dimensional numerical investigation on wall film formation and evaporation in port fuel injection engines

Cycle-by-Cycle Analysis of Cold Crank-Start in a GDI Engine

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