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International Journal of Automotive Technology 2009;10(5): 545-553. |
| EFFECT OF THE FUEL INJECTION STRATEGIES ON THE COMBUSTION PROCESS IN A PFI BOOSTED SI ENGINE |
| S. S. MEROLA, P. SEMENTA, C. TORNATORE, B. M. VAGLIECO |
| Istituto Motori-CNR |
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| ABSTRACT |
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A low-cost solution based on fuel injection strategies was investigated to optimize the combustion process in a boosted ported fuel injection spark ignition (PFI SI) engine. The target was to reduce the fuel consumption and the pollutants emissions keeping the same performances. It was studied the effect of the fuel injection at closed and open valve condition and of the Multiple Injection Strategies (MIS) based on double and triple fuel injection in the open-valve condition. The tests were performed on an optical accessible single-cylinder PFI SI engine equipped with an external boost device. The engine was operated at full load and at stoichiometric equivalent ratio with commercial gasoline. Optical techniques based on 2D-digital imaging were used to follow the flame propagation from the flame kernel until the late combustion phase. In particular, the diffusion-controlled flames near the valves and the cylinder walls due to the fuel depositions were studied. In these conditions the presence of soot was measured by the two-colour pyrometry, it was correlated with the engine parameters and with exhaust emissions measured by conventional methods. The open valve fuel injection strategies demonstrated better combustion process efficiency than the closed valve one. They provided very low soot levels in the combustion chamber and at the engine exhaust and a reduction in the specific fuel consumption. The multiple injection strategies proved to be the best solution in terms of performance, soot concentration and fuel consumption. |
| Key Words:
PFI SI Engine, Boosting, Multiple Fuel Injection Strategies, Fuel deposition, Optical diagnostics |
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