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1

Selection of ion sensor operating parameters in quasi-static conditions

Fiedkiewicz Łukasz, Pielecha Ireneusz

Combustion Engines

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2019

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R. 58, nr 4

254--258

EN

Evaluating combustion quality using sensors that allow continuous assessment of the process is one of the modern methods of engine sensory diagnostics. The proper calibration of such systems is a task that requires many studies to determine the conditions and quantities affecting the process. The analysis of significance of quantities related to the ionization signal was carried out in the article. The magnitude of the voltage generating the electric field, the type of spark plug used, the distance of the spark plug electrodes and the dynamic factor - spark plug operating temperature - were all tested. The tests were carried out using a CNG burner (with an excess air ratio of λ = 1) and four spark plugs. As a result of the ionization signal research, the following relationships were obtained: regarding the impact of the sensor position on the amount of generated voltage (the smaller the distance the greater the value of the signal), the effect of temperature on the sensor resistance (non-linear relationship: increase in temperature decreases resistance, with R2 = 0.9997) effect of system voltage on the ionization signal (linear relationship: voltage increase increases the ionization current signal with a determination coefficient of R2 = 0.9803). In addition, it was found that using an iridium electrode candle had the best effects on the ionization current, regardless of the electrode’s geometrical parameters.

2

Relations between ion signal and flame propagation in cylinder of a rapid compression machine

Fiedkiewicz Łukasz, Pielecha Ireneusz

Combustion Engines

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2019

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R. 58, nr 4

264--268

EN

Internal combustion engine diagnostics using traditional methods of cylinder pressure signal processing limits the amount of information available about the combustion process. It is necessary to conduct research in order to obtain more precise information - in-creasing the combustion process diagnosis potential. One such suggestion is the use of an ionization signal and an attempt to link it to the flame development during combustion of gaseous fuels. The article attempts to identify such a relationship using a rapid compression machine due to optical access it provides to the combustion chamber. As a result of the research, the relationships between the ionization voltage (chemical and thermal) of the first combustion phase and the corresponding flame development rates were determined. A relatively high coefficient of determination value was obtained for both relations, which indicates the possibility of obtaining diagnostic information about the combustion process from the ionization signal.

3

Prechamber optimal selection for a two stage turbulent jet ignition type combustion system in CNG-fuelled engine

Pielecha Ireneusz, Bueschke Wojciech, Skowron Maciej, Fiedkiewicz Łukasz, Szwajca Filip

Combustion Engines

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2019

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R. 58, nr 1

16--26

EN

Searching for further reduction of fuel consumption simultaneously with the reduction of toxic compounds emission new systems for lean-mixture combustion for SI engines are being discussed by many manufacturers. Within the European GasOn-Project (Gas Only Internal Combustion Engines) the two-stage combustion and Turbulent Jet Ignition concept for CNG-fuelled high speed engine has been proposed and thoroughly investigated where the reduction of gas consumption and increasing of engine efficiency together with the reduction of emission, especially CO2 was expected. In the investigated cases the lean-burn combustion process was conducted with selection of the most effective pre-combustion chamber. The experimental investigations have been performed on single-cylinder AVL5804 research engine, which has been modified to SI and CNG fuelling. For the analysis of the thermodynamic, operational and emission indexes very advanced equipment has been applied. Based on the measuring results achieved for different pre-chamber configurations the extended methodology of polioptimization by pre-chamber selection and the shape of main chamber in the piston crown for proposed combustion system has been described and discussed. The results of the three versions of the optimization methods have been comparatively summarized in conclusions.