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The paper discusses the analysis of ethanol (E85) fuel atomization generated by piezoelectric fuel injectors operating in a high-pressure gasoline direct injection system. The methodology and tests results of the influence of the fuel (E85) injection pressure and combustion chamber back pressure on the changes of the fuel spray geometrical parameters during the injection and on the values characterizing the injection quality have been presented in the paper. The tests were performed for one value of the air backpressure (1.5 MPa; as in modern supercharged DI engines) at the injection pressures of 5 and 20 MPa. The following comparative indexes were analyzed: linear and radial spray penetration during the injection and the velocity of the spray propagation. The investigation consisted in a visual recording of the process of fuel (ethanol E85) injection realized into a high pressure chamber.

The paper presents the thermodynamic analysis of the engine supplied with small and large diesel fuel doses while increasing natural gas quantity. The paper presents changes in the combustion process thermodynamic indexes and changes in the exhaust gas emissions for dynamically increased share of the gaseous fuel. The cylinder pressure history was subject to thermodynamic analysis, . based on which the mean indicated pressure, the heat release rate, the quantity of heat released as well as the pressure rate increase after self-ignition were determined. These parameters were also referred to the subsequent engine operation cycles by specifying the scope of the change per cycle. The relationship between the engine load and the start, the center and the end of combustion while increasing the gas amount supplied to the cylinder was indicated.

The modern solution of two-stage combustion, namely the Turbulent Jet Ignition, enables the combustion of ultra-lean mixtures. Thanks to this solution, it became possible to reduce fuel consumption and, at the same time, to increase the combustion process indicators (including the overall combustion system efficiency). The article presents the results of numerical tests of a heavy-duty engine equipped with the TJI system running on hydrogen fuel. The operating conditions of the Heavy-Duty engine at n = 1500 rpm and IMEP = 10 bar with a prechamber with 7 holes were analyzed. The research was conducted with the use of lean mixtures (global lambda ca. 2 or more). The AVL FIRE software was used to perform the analysis of different fuel doses delivered to the main chamber, with a constant global excess air coefficient value. Increasing the proportion of hydrogen in the pre-chamber resulted in its reduction in the main chamber.