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Internal combustion engine diagnostics using statistically processed Wiebe function

Famfulik Jan, Richtar Michal, Smiraus Jakub, Muckova Petra, Sarkan Branislav, Dresler Pavel

Eksploatacja i Niezawodność

2021

Vol. 23, no. 3

505--511

The aim of the article is to present the concept of an indirect diagnostic method using the assessment of the variability of the amount of released heat (mass fraction burn) and the heat release rate. The Wiebe function for the assessment of variability has been used. The Wiebe function parameters from the course of the high-pressure indication in the cylinder of internal combustion engine using linear regression have been calculated. From a sufficiently large number of measured samples, the upper and lower limits of the Wiebe function parameters have been statistically determined. Lower and upper limits characterize variability of the heat release process not only in terms of quantity but also in terms of heat release rate. The assessment of variability is thus more complicated than using one integral indicator, typically the mean value of amount of the released heat. The procedure enabling a more accurate estimation of heat generation beginning has been shown. For the combustion process variability assessment of the engine, statistical test of relative frequencies has been used.

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

Przybyła G., Postrzednik S., Żmudka Z.

Journal of KONES

2016

Vol. 23, No. 2

293--300

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.

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

2008

Vol. 15, No. 3

567-574

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.