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Correlations of wiebe function parameters for combustion simulation in SI engine fuelled with gaseous fuels

Przybyła G., Postrzednik S., Żmudka Z.

Journal of KONES

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2016

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Vol. 23, No. 2

293--300

EN

Combustion simulation in SI engine fuelled with unconventional gaseous fuels becomes more necessary in last years. The reason is because the use of e.g. biogases from anaerobic digester process or gasification of biomass to produce "green energy". From the view of energy balance of small CHP units, the SI engine seems to be most efficient appliance as a part of this unit. Through 1D, simulation of in-cylinder pressure a fast prediction of engine performance is possible. In this case, the Mass Fraction Burn (MFB) function can be used. The MFB reflect the amount of fuel burned throughout the combustion process in an internal combustion engine. SI engine combustion simulation by using a Wiebe function to represent the MFB is very often used in a 1D-engine code that allow for fast calculations and a good accuracy of results. This paper deals with calculations of Wiebe function coefficients based on experimental data of four stroke naturally aspirated SI engine fuelled with natural gas and simulated producer gas. The Wiebe function parameters are determined over a range of fuel compositions and air excess ratio by fitting the Wiebe function curve to the experimentally obtained MFB data from a single-zone Heat Release Rate (HRR) analysis.

2

Wiebe function parameter determination for mass fraction burn calculation in an ETHANOL-GASOLINE fuelled SI engine

Yeliana, Cooney C., Worm J., Michalek D., Naber J.

Journal of KONES

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2008

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Vol. 15, No. 3

567-574

EN

The Mass Fraction Burn (MFB) and Heat Release Rate (HRR) reflect the amount of fuel burned and the rate of burning throughout the combustion process in an internal combustion engine. These parameters play a crucial role in research and development endeavours focused on engine efficiency, emissions, and overall operating performance. Analytically in a Spark-Ignition (SI) engine, these parameters are often modelled with the Wiebe function, a well known mass fraction burn formulation, which is a function of "a" (efficiency parameter), "m" (form factor), crank angle, and the duration of combustion. This function is a simple but powerful correlation model that is well suited for zero and one dimensional engine cycle simulations. In this work, the Wiebe function parameters are determined over a range of fuel compositions and compression ratios by fitting the Wiebe function curve to the experimentally obtained MFB data from a single-zone HRR analysis. The Wiebe function parameters are determined using a curve fitting model by finding the minimum of a scalar function of several variables. This functionality has been built into the single-zone mass fraction burned model. Experiments with five ethanol-gasoline fuel blends: E0 (gasoline), E20, E40, E60, and E84 were conducted on a SI Cooperative Fuels Research (CFR) engine while holding a constant load of 330 kPa Net Indicated Mean Effective Pressure (Net IMEP). There were five methods introduced to fit the Wiebe function parameters, which utilized a combination of least square method and direct algebraic solution. This paper details the process used to determine the Wiebe function parameters, and compare the results obtained using these methods for the ethanol-gasoline mixture concentrations.

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Property determination for ethanol-gasoline blends with application to mass fraction burn analysis in a spark ignition engine

Yeliana, Worm J., Michalek D., Naber J.

Journal of KONES

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2008

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Vol. 15, No. 2

553-561

EN

The Mass Fraction Burn (MFB) and Heat Release Rate (HRR) reflects the amount of fuel burned, and the rate of burning throughout the combustion process in an internal combustion engine. These parameters play a crucial role in research and development endeavors focused on engine efficiency, emissions, and overall operating performance. They are computed by analyzing measured pressure data and applying thermodynamic principals to determine the energy released during the combustion process. Thus, the properties of the fuel-air and combusted gas mixtures play an important role in the analysis. Engine pressure data were taken from a Spark-Ignition Cooperative Fuels Research (CFR) engine operating at a constant load of 330 kPa Net Indicated Mean Effective Pressure (Net IMEP) and using five ethanol-gasoline fuel blends: E0 (gasoline), E20, E40, E60, and E84. The fuels were assumed to be in a non-reacting state throughout the mixing process. Once the fuel mixture properties were known, the fuel-air and burned mixture properties were determined using the fuel-air mass ratio. The analysis presented within this paper details the process by which the fuel, fuel-air, and burned mixture properties can be determined. The MFB of five different fuel blends at a chosen operating condition was also presented along with the pressure trace, the temperature and the gamma profile at the end of this paper.