Measurements of Local In-Cylinder Fuel Concentration Fluctuations in a Firing SI Engine

Koenig, Michael; Hall, Matthew J.

doi:10.4271/971644

Cited by 31 publications

(4 citation statements)

References 24 publications

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“…There are several approaches to studying fuel concentrations in an SI engine, including infrared (IR) absorption, planar laser induced fluorescence (PLIF), Raman scattering, laser-induced breakdown spectroscopy (LIBS) and spark-induced breakdown spectroscopy (SIBS) or spark emission spectroscopy. A 3.392-μm He-Ne laser was used to obtain fuel concentrations for combustion diagnostics [17][18][19][20][21][22][23][24][25][26]. One of the members of our group was the first to investigate the possibility of measuring fuel concentration near the spark plug in a test engine [21].…”

Section: Introductionmentioning

confidence: 99%

Local fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine

Rahman

Kawahara

Matsunaga

et al. 2016

International Journal of Hydrogen Energy

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Quantitative measurements of local fuel concentrations were conducted in a directinjection hydrogen spark-ignition research engine using the spark-induced breakdown spectroscopy (SIBS) technique. For SIBS measurements, a new sensor was developed from a commercially available M12-type spark plug with no major modifications to the electrodes. The new plug sensor showed better durability and required less maintenance when used in a hydrogen research engine. Emission spectra from the plasma generated by the spark plug were collected through an optical fibre housed in the centre electrode of the plug and resolved spectrally for atomic emissions of H α , O(I), and N(I). The main focus of the present work was to characterise the effects of ambient pressure at ignition timing on spectral line emissions and to improve the accuracy of SIBS measurements by taking into account the pressure dependency of atomic emissions. A significant effect of the corresponding pressure at ignition timing was observed on spark-induced breakdown spectroscopic measurements and emission line characteristics. Retarded spark timing (i.e. higher ambient pressure at the ignition site) resulted in lower spectral line intensities as well as weaker background emissions. It is well established that with relatively higher pressure and density of atoms or molecules, the cooling of expanding plasma accelerates, and the collision probability increases, leading to both a weaker broadband [2] continuum and atomic emissions. A "calibration MAP" representing the correlation of air excess ratio (relative air/fuel ratio) with both intensity ratio and pressure at ignition timing was created and subsequently used for quantitative measurements of local fuel concentrations for both port injection and direct injection strategies to demonstrate and explore the effects of pressure dependency of atomic emission on the accuracy of the SIBS measurements. Local stratification of the fuel mixture in the vicinity of the spark gap location associated with direct injection strategies was confirmed; the coefficient of variation of the local air excess ratio was relatively small for measurements made using the calibration map. This demonstrated that the measurement accuracy of local fuel concentrations through a spark plug sensor can be improved significantly when the pressure dependency of atomic emissions is taken into account.

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Section: Introductionmentioning

confidence: 99%

Local fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine

Rahman

Kawahara

Matsunaga

et al. 2016

International Journal of Hydrogen Energy

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“…The first study investigated the possibility of obtaining fuel concentration measurements near the spark plug in a test engine [16]. Koenig and Hall [17,18] used an optical sensor inside the spark plug to obtain the fuel concentration. Kawamura et al [19] used a 3.392 µm laser, instead of an infrared lamp, with almost the same optical arrangement as Koenig and Hall.…”

Section: Introductionmentioning

confidence: 99%

In situmeasurement of hydrocarbon fuel concentration near a spark plug in an engine cylinder using the 3.392 m infrared laser absorption method: application to an actual engine

Tomita

Kawahara

Nishiyama

et al. 2003

Meas. Sci. Technol.

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An infrared absorption method with a 3.392 µm He–Ne laser was used to determine the hydrocarbon fuel concentration near the spark plug in a spark-ignition engine. Iso-octane was used for the fuel. The pressure and temperature dependence of the molar absorption coefficient was clarified. The molar absorption coefficients of a multi-component fuel such as gasoline were estimated by using the coefficient of each component and considering the mass balance. A sensor was developed and installed in a spark plug, which was substituted in place of an ordinary spark plug in a spark-ignition engine. Light can pass from the sensor through the engine cylinder to measure the fuel concentration. The effects of liquid droplets inside the engine cylinder, mechanical vibrations and other gases such as H2O and CO2 on the measurement accuracy were considered. Four main conclusions were drawn from this study. First, the pressure and temperature effects on the molar absorption coefficient of liquid fuel vapour were determined independently in advance using a constant-volume vessel. The pressure and temperature dependence of the molar absorption coefficient was determined under engine firing conditions. Second, the molar absorption coefficients of a multi-component hydrocarbon fuel such as gasoline were estimated by considering the molar fraction of each component. Third, in situ measurements of the hydrocarbon fuel concentration in an actual engine were obtained using the spark plug sensor and the molar absorption coefficient of iso-octane. The concentration near the spark plug just before ignition was almost in agreement with the mean value that was obtained from the measurement of the flow rate made with a burette, which represented the mean value averaged over many cycles. And fourth, no liquid droplets were observed at near-idling conditions. The effects of other gases, such as CO, CO2 and H2O, can be neglected.

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“…Several groups have developed in-situ optical probes for measuring hydrocarbon concentration using infrared light absorption (Mongia et al, 1996;Hase and Kori, 1996;and Koenig and Hall, 1997). Hydrocarbons have a strong absorption band at around 3.39 gm (11 the infrared) due to a CH vibrational transition.…”

Section: Spatial and Temporal Uniformity Measurement Techniquesmentioning

confidence: 99%

Fast Response Extraction Probe for Measurement of Air-Fuel Ratio Fluctuations in Lean Premixed Combustors

Mongia

Torres

Dibble

et al. 1999

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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The extent of air and fuel mixing prior to combustion in lean premixed combustion has been shown to drastically affect combustor performance, both in terms of emissions and stability. Standard extraction probes are often used for measuring the spatial (average over time) distribution of fuel concentration. However, the temporal fluctuations in fuel mole fraction, which are averaged by conventional extraction probes, have been also shown to drastically affect combustor performance. Several methods have been developed to measure the fluctuations in fuel mole fraction both temporally and spatially. These techniques are often difficult or impossible to apply to an operating combustor at high pressures and temperatures. In this paper, we describe a Fast Response Extraction Probe (FREP) which is capable of measuring temporal mole fraction fluctuations up to frequencies of 1 kHz. A short, capillary tube is inserted into the premixing passage (which is at high pressure) for sampling the flow. The capillary tube is connected to a small gas cell at atmospheric pressure. Light from a 3.39 μm He-Ne laser is passed through the gas cell. By measuring the absorption of laser light, the concentration of hydrocarbons can be determined. The temporal response of the system is dependent on the geometry of the gas cell and sampling tube and the pressure drop through the sampling tube. A model for predicting the time response of the FREP is presented and compared to a laboratory scale experiment. The FREP was also tested in a high-pressure combustion rig at United Technologies Research Center. It is shown that the FREP is capable of measuring fuel-air fluctuations at gas turbine conditions. It is also shown that, at the conditions studied, there is a relationship between pressure oscillations and fuel mole fraction oscillations.

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Measurements of Local In-Cylinder Fuel Concentration Fluctuations in a Firing SI Engine

Cited by 31 publications

References 24 publications

Local fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine

Local fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine

In situmeasurement of hydrocarbon fuel concentration near a spark plug in an engine cylinder using the 3.392 m infrared laser absorption method: application to an actual engine

Fast Response Extraction Probe for Measurement of Air-Fuel Ratio Fluctuations in Lean Premixed Combustors

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