Influence of Failures not Detected by the On-Board Diagnostic System on the Performance and Pollutant Emissions of a Spark Ignition Engine

Author(s):  
Jairo Castillo-Calderón ◽  
Diego Díaz Sinche ◽  
Rubén Carrión Jaura ◽  
Diego Rivera Campoverde
Author(s):  
Nicolas Iafrate ◽  
Anthony Robert ◽  
Jean-Baptiste Michel ◽  
Olivier Colin ◽  
Benedicte Cuenot ◽  
...  

Downsized spark ignition engines coupled with a direct injection strategy are more and more attractive for car manufacturers in order to reduce pollutant emissions and increase efficiency. However, the combustion process may be affected by local heterogeneities caused by the interaction between the spray and turbulence. The aim for car manufacturers of such engine strategy is to create, for mid-to-high speeds and mid-up-high loads, a mixture which is as homogeneous as possible. However, although injection occurs during the intake phase, which favors homogeneous mixing, local heterogeneities of the equivalence ratio are still observed at the ignition time. The analysis of the mixture preparation is difficult to perform experimentally because of limited optical accesses. In this context, numerical simulation, and in particular Large Eddy Simulation (LES) are complementary tools for the understanding and analysis of unsteady phenomena. The paper presents the LES study of the impact of direct injection on the mixture preparation and combustion in a spark ignition engine. Numerical simulations are validated by comparing LES results with experimental data previously obtained at IFPEN. Two main analyses are performed. The first one focuses on the fuel mixing and the second one concerns the effect of the liquid phase on the combustion process. To highlight these phenomena, simulations with and without liquid injection are performed and compared.


Author(s):  
Emiliano Pipitone ◽  
Salvatore Caltabellotta

Abstract In-cylinder expansion of internal combustion engines based on Diesel or Otto cycles cannot be completely brought down to ambient pressure, causing a 20% theoretical energy loss. Several systems have been implemented to recover and use this energy such as turbocharging, turbo-mechanical and turbo-electrical compounding, or the implementation of Miller Cycles. In all these cases however, the amount of energy recovered is limited allowing the engine to reach an overall efficiency incremental improvement between 4% and 9%. Implementing an adequately designed expander-generator unit could efficiently recover the unexpanded exhaust gas energy and improve efficiency. In this work, the application of the expander-generator unit to a hybrid propulsion vehicle is considered, where the onboard energy storage receives power produced by an expander-generator, which could hence be employed for vehicle propulsion through an electric drivetrain. Starting from these considerations, a simple but effective modelling approach is used to evaluate the energetic potential of a spark-ignition engine electrically supercharged and equipped with an exhaust gas expander connected to an electric generator. The overall efficiency was compared to a reference turbocharged engine within a hybrid vehicle architecture. It was found that, if adequately recovered, the unexpanded gas energy could reduce engine fuel consumption and related pollutant emissions by 4% to 12%, depending on overall power output.


2021 ◽  
Vol 11 (13) ◽  
pp. 6035
Author(s):  
Luigi Teodosio ◽  
Luca Marchitto ◽  
Cinzia Tornatore ◽  
Fabio Bozza ◽  
Gerardo Valentino

Combustion stability, engine efficiency and emissions in a multi-cylinder spark-ignition internal combustion engines can be improved through the advanced control and optimization of individual cylinder operation. In this work, experimental and numerical analyses were carried out on a twin-cylinder turbocharged port fuel injection (PFI) spark-ignition engine to evaluate the influence of cylinder-by-cylinder variation on performance and pollutant emissions. In a first stage, experimental tests are performed on the engine at different speed/load points and exhaust gas recirculation (EGR) rates, covering operating conditions typical of Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). Measurements highlighted relevant differences in combustion evolution between cylinders, mainly due to non-uniform effective in-cylinder air/fuel ratio. Experimental data are utilized to validate a one-dimensional (1D) engine model, enhanced with user-defined sub-models of turbulence, combustion, heat transfer and noxious emissions. The model shows a satisfactory accuracy in reproducing the combustion evolution in each cylinder and the temperature of exhaust gases at turbine inlet. The pollutant species (HC, CO and NOx) predicted by the model show a good agreement with the ones measured at engine exhaust. Furthermore, the impact of cylinder-by-cylinder variation on gaseous emissions is also satisfactorily reproduced. The novel contribution of present work mainly consists in the extended numerical/experimental analysis on the effects of cylinder-by-cylinder variation on performance and emissions of spark-ignition engines. The proposed numerical methodology represents a valuable tool to support the engine design and calibration, with the aim to improve both performance and emissions.


Author(s):  
Andreas A. Malikopoulos ◽  
Panos Y. Papalambros ◽  
Dennis N. Assanis

Advanced internal combustion engine technologies have increased the number of accessible variables of an engine and our ability to control them. The optimal values of these variables are designated during engine calibration by means of a static correlation between the controllable variables and the corresponding steady-state engine operating points. While the engine is running, these correlations are being interpolated to provide values of the controllable variables for each operating point. These values are controlled by the electronic control unit to achieve desirable engine performance, for example in fuel economy, pollutant emissions, and engine acceleration. The state-of-the-art engine calibration cannot guarantee continuously optimal engine operation for the entire operating domain, especially in transient cases encountered in driving styles of different drivers. This paper presents the theoretical basis and algorithmic implementation for allowing the engine to learn the optimal set values of accessible variables in real time while running a vehicle. Through this new approach, the engine progressively perceives the driver’s driving style and eventually learns to operate in a manner that optimizes specified performance indices. The effectiveness of the approach is demonstrated through simulation of a spark ignition engine, which learns to optimize fuel economy with respect to spark ignition timing, while it is running a vehicle.


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