Detailed modeling of common rail fuel injection process

Modeling of fuel injection equipment is a tool that is used increasingly for explaining or predicting the effect of advanced diesel injection strategies on combustion and emissions. This paper reports on the modeling of the high-pressure part of a research type Heavy Duty Common Rail (CR) fuel injection system. More specifically, it reports on the observed dynamics of the injection system and the capability of the model to capture this. For that reason, the total high-pressure part of the injection system, i.e. the fuel pump, rail and injector, has been modeled using the AMESim code (Imagine S.A., 2004). The reliability of the resulting hydraulic model is tested through a comparison between numerical results and actual injection measurements. This detailed comparison is based on measurements of injected mass flow rate, needle lift and pressure oscillations in the injection duct for a series of single injection events. It is shown that the hydraulic model is able to accurately simulate the injection rate, needle lift and injection pressure for different rail pressure levels. For accurate numerical results, it is vital that the stiffness of the injector needle assembly and the discharge coefficients of the different flow restrictions in the injector (e.g. nozzle holes) are correctly modeled. Assuming a rigid injector needle results in a too early start of injection. Discharge coefficient values found in literature shows a wide spread. This makes it very difficult to simulate the injected mass flow rate accurately on the basis of literature data. Using the measured injected mass of fuel to tune the discharge coefficient, together with the inclusion of the elasticity of the injector needle, results in a good approximation of the injection rate

Modelling of common rail fuel injection system and influence of fluid properties on injection process

This paper focuses on the modelling of a research type Heavy Duty Common Rail (CR) fuel injection system. More specifically it reports on the observed interaction between fuel properties and injection and on the capability to model this. For that reason a hydraulic model of the fuel injection system has been developed using the AMESim code (Imagine S.A., 2003). The reliability of the numerical results is tested through a comparison between numerical and experimental results when using regular diesel fuel. Basis for this detailed comparison are measurements of injected mass flow rate, needle lift and pressure oscillations in the injection duct for a single injection. Simulation results for regular diesel show good agreement with measured data for pressure oscillations in the injection duct, needle lift and injected fuel mass flow rate. A comparison of experimental and simulated results for Rapeseed oil Methyl Ester (RME) also shows good correspondence, which proves the capability of the model to capture the influence of different fuel properties

An OBD strategy to estimate SCR ageing and detect urea injection faults

\u3cp\u3eThe most recent regulation for diesel engines with regards to NO\u3csub\u3ex\u3c/sub\u3e emissions and SCR systems considers stringent OBD requirements. In this paper, an observer of the ageing state is developed considering NO, NO\u3csub\u3e2\u3c/sub\u3e and NH\u3csub\u3e3\u3c/sub\u3e concentrations, the surface coverage ratio θ\u3csub\u3eNH3\u3c/sub\u3e, and the ammonia storage capacity Ω as states. The observer is based on an extended Kalman filter and the SCR downstream NO\u3csub\u3ex\u3c/sub\u3e and NH\u3csub\u3e3\u3c/sub\u3e measurements. Accuracy and convergence time are presented for the observer validation in simulation in a dynamic WHTC at warm starting conditions. As the ageing state estimation is based on the residual between a model and measurements, an additional indicator avoids associating an error inherent of urea injection faults to ageing. The performance of this indicator is independent from the ageing state of the SCR. The highly detailed, physics-based 1D SIMCAT model is used as the SCR plant for the ageing estimation and as the model to track the urea injected quality. Then, a control-oriented model is also used in simulation to allow the state-space representation required for the observer. Accuracy of both models is argued, showing the limitations and advantages of the control-oriented model.\u3c/p\u3

Cylinder pressure-based control in heavy-duty EGR diesel engines using a virtual heat release and emission sensor

This paper presents a cylinder pressure-based control (CPBC) system for conventional diesel combustion withhigh EGR levels. Besides the commonly applied heat release estimation, the CPBC system is extended with anew virtual NOx and PM sensor. Using available cylinder pressure information, these emissions are estimatedusing a physically-based combustion model. This opens the route to advanced On-Board Diagnostics and tooptimized fuel consumption and emissions during all operating conditions.The potential of closed-loop CA50 and IMEP control is demonstrated on a multi-cylinder heavy-duty EGRengine. For uncalibrated injectors and fuel variations, the combustion control system makes the engineperformance robust for the applied variations and reduces the need for a time consuming calibration process.Cylinder balancing is shown to enable auto-calibration of fuel injectors and to enhance fuel flexibility. For bothBiodiesel and US diesel, the effects on NOx and PM emissions are partly compensated for by combined CA50and IMEP control. This can be further improved by application of (virtual) emission sensors. Furthermore, it isshown that this combustion controller shows good transient performance during load changes.The virtual emission sensor is successfully implemented for real-time control. For operating conditions withhigh EGR rates and varying injection timing, the predictions of the virtual NOx and PM sensor are comparedwith measurements. NOx emission prediction inaccuracy is typically on the order of 12%, which is comparableto commercially available sensors. The predicted PM emissions show good qualitative agreement, but needfurther improvement for application in DPF regeneration and PM emission control strategies. Robust emissioncontrol is essential to meet future requirements for On-Board Diagnostics and In-Use Compliance

Experimental validation of extended NO and Soot model for advanced HD Diesel Engine Combustion

A computationally efficient engine model is developed based on an extended NO emission model and state-of-the-art soot model. The model predicts exhaust NO and soot emission for both conventional and advanced, high-EGR (up to 50 %), heavy-duty DI diesel combustion. Modeling activities have aimed at limiting the computational effort while maintaining a sound physical/chemical basis. The main inputs to the model are the fuel injection rate profile, in-cylinder pressure data and trapped in-cylinder conditions together with basic fuel spray information. Obtaining accurate values for these inputs is part of the model validation process which is thoroughly described. Modeling results are compared with single-cylinder as well as multi-cylinder heavy-duty diesel engine data. NO and soot level predictions show good agreement with measurement data for conventional and high-EGR combustion with conventional timing

CO2 neutral heavy-duty engine concept with RCCI combustion using seaweed-based fuels

\u3cp\u3eThis paper focusses on the application of bioalcohols (ethanol and butanol) derived from seaweed in Heavy-Duty (HD) Compression Ignition (CI) combustion engines. Seaweed-based fuels do not claim land and are not in competition with the food chain. Currently, the application of high octane bioalcohols is limited to Spark Ignition (SI) engines. The Reactivity Controlled Compression Ignition (RCCI) combustion concept allows the use of these low carbon fuels in CI engines which have higher efficiencies associated with them than SI engines. This contributes to the reduction of tailpipe CO\u3csub\u3e2\u3c/sub\u3e emissions as required by (future) legislation and reducing fuel consumption, i.e. Total-Cost-of-Ownership (TCO). Furthermore, it opens the HD transport market for these low carbon bioalcohol fuels from a novel sustainable biomass source. In this paper, both the production of seaweed-based fuels and the application of these fuels in CI engines is discussed. Ethanol and butanol are considered as the most viable fuels derived from seaweed. The potential of these fuels has been evaluated for the dual-fuel RCCI mode regarding efficiency and NOx emissions. The operating conditions that have been varied are mainly the fuel blend ratio (BR), fuel injection timing, and EGR rate on both a HD single-cylinder and on a HD multi-cylinder engine. The results for E85/diesel-RCCI demonstrate that CI engine-like efficiencies are feasible. The gross Indicated Thermal Efficiency (ITE) reaches up to 52% and 46.5% using E85 in a single-cylinder and a multi-cylinder engine, respectively. The first results using biomass based butanol show greater difficulty in realizing targeted efficiencies on the multi-cylinder engine due to the higher fuel reactivity and higher boiling temperature than ethanol. The gross ITE reaches up to 51.6% and 38.5% using butanol in a single-cylinder and a multi-cylinder engine, respectively. The demonstrated potential of seaweed-based fuels is an important driver for upscaling the production process of these fuels. Furthermore, future development activities will focus on improving the brake thermal efficiency of the RCCI engine running on seaweed-based fuels. Improving the low reactivity fuel-air mixture preparation will be key to achieve this.\u3c/p\u3

Model-based control development for future Diesel engines

Heavy duty diesel vehicles compliant with current Euro VI/EPA13 emission limits employ aftertreatment systems based on DOC/DPF technology for soot and particulate matter reduction and SCR catalysts with urea dosing for NO x reduction. Traditionally, the majority of the control systems used for urea dosing are map based. However, increasing system complexity combined with real-world performance requirements are a strong motivation to switch to a model-based control approach. Firstly, this article describes a model-based design approach for aftertreatment control development. Focus is on urea dosing control for Euro VI level SCR systems. To achieve the legal emissions limits, including in-service conformity over the vehicle lifetime, advanced model-based control strategies enable maximal NO x conversion in combination with minimum ammonia slip, while ensuring robustness against real-life disturbances. Simulation and experimental results of the control system are presented, which demonstrate the performance and robustness properties. Following this model-based approach, a concept study is performed to explore aftertreatment and control technologies to achieve ultra-low NO x emissions as will be imposed by regulatory bodies in the near future. It is shown that aftertreatment concepts with Passive NO x Adsorber and SCR on DPF are most promising. To optimize overall engine-aftertreatment performance, the modelbased control approach is extended towards Integrated Emission Management(IEM). Based on the actual system state, this supervisory controller minimizes operating costs at each instant in time under all operating conditions. This is key for costoptimal and robust performance

High speed shadowgraphic, macroscopic characterization of diesel fuel sprays in a high pressure cell

No abstract