In-Cylinder Oxygen Concentration Estimation Based on Virtual Measurement and Data Fusion Algorithm for Turbocharged Diesel Engines

In-cylinder oxygen concentration (ICOC) is critical for advanced combustion control of internal combustion engines, and is hard to be accessed in commercial measurements. In existing research, ICOC is predicted by conventional dynamical model based on mass/energy conservation, which suffers from uncertainties such as inaccuracy of volumetric efficiency or the error of orifice geometry. In this paper, we enhance the ICOC estimation by implementing two vital strategies. Firstly, we introduce a method called virtual measurement to resist the conventional model uncertainties, in this method we modeling the ICOC as a function of ignition delay which can be obtained by measuring the in-cylinder pressure. Secondly, we apply Kalman filter to fuse the ICOC results from the conventional dynamical model and the virtual measurement. The data fusion algorithm turns the estimation to a predictor-corrector fashion, which further improves the overall accuracy and robustness. The proposed approach is validated through a calibrated GT-Power engine model. The results show that the estimation error can be achieved form at worst 0.03 to at best 0.01 on steady state.

Unsteady characteristics of jet combustion in a supersonic combustor with a micro-vortex generator

To clarify the effect of the micro-vortex generator on the unsteady characteristics of jet combustion, a set of experiments had been carried out in a cavity-based supersonic combustor. Based on the advanced combustion diagnosis techniques, the ignition process, initial cavity-stabilized flame and dynamic flame development at the initial equivalence ratio of 0.20 are revealed in detail. Although the ignition processes are identical, the time for the flame propagation process in the cavity can be shortened when an MVG (micro-vortex generator) is located properly upstream of the injection. The initial flame cannot be stabilized in the combustor if the MVG is too close to the injection. After achieving initial stable combustion, the chemical reactions in the flame front are more vigorous and the shear layer can be lifted a little higher in the experiment with an MVG. At the same dynamic fuel adjustment method, the flame can be stabilized in the combustor without an MVG while the flame is blown out with an MVG. Based on numerous experimental results, it is found that the MVG dwindles the adjustment range of the dynamic injection, which makes against the stability of the flame when the engine decreases the thrust.

Unique structure of active platinum-bismuth site for oxidation of carbon monoxide

As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO2 production rate of 487 μmolCO2·gPt−1·s−1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt−O−Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction.

Evaluation of control-oriented flame propagation models for production control of a spark-assisted compression ignition engine

The drive to improve internal combustion engines has led to efficiency objectives that exceed the capability of conventional combustion strategies. As a result, advanced combustion modes are more attractive for production. These advanced combustion strategies typically add sensors, actuators, and degrees of freedom to the combustion process. Spark-assisted compression ignition (SACI) is an efficient production-viable advanced combustion strategy characterized by spark-ignited flame propagation that triggers autoignition in the remaining unburned gas. Modeling this complex combustion process for control demands a careful selection of model structure to maximize predictive accuracy within computational constraints. This work comprehensively evaluates a physics-based and a data-driven model. The physics-based model produces a burn duration by computing laminar flame speed as a function of test point conditions. The crank-angle domain is intentionally excluded to reduce computational expense. The data-driven model is an artificial neural network (ANN). The candidate models are compared to a one-dimensional engine model validated to experimental SACI engine data. Though both models capture the trends in burn rates, the ANN model has a root-mean square error (RMSE) of 1.4 CAD, significantly lower than the 10.4 CAD RMSE of the physics-based model. The exclusion of the crank-angle domain results in insufficient detail for the physics-based model, while the ANN can tolerate this exclusion.

Modelling adiabatic flame temperature for methane with an overview for advanced combustion process: flameless combustion

In this study, we have carried out to modeling by mathematical equations the environment of the combustion chamber under some conditions using the software MATLAB in order to make an adequate algorithm of resolution and get solution of the different equations that taken part in the phenomenon of combustion, so the first was to identifies the kind of the fuel to use in that model (taking Methane as fuel combustion) and minimizing the reduction of novice gas burned is in priority, for this, we want to establish the optimal values to take to preserve the environment, especially from CO2 and CO emissions, secondly, its nature according to the equivalent ratio (lean, stoichiometric or rich mixture), all variations of equivalent ratio, the third idea is to retrace the ways of a different product of the reaction and see their variations compared to the equivalent ratio, once traced, we can improvise which exact place in the reaction, a product will be finished either in the form of a gas or to decompose in order to bind to another and form another component. We also discussed the percentage of O2 and H2O emissions for an interesting viewpoint of the environmental aspect of hydrocarbon’s chemical reaction. Another additional part will be dedicated to the process of flameless combustion to write its mathematical equation, compare it with the so-called traditional one, and see the variations in the temperature according to the equivalent ratio.

Exploring the potential benefits of high-efficiency dual-fuel combustion on a heavy-duty multi-cylinder engine for SuperTruck I

In support of the Daimler SuperTruck I team’s 55% brake thermal efficiency (BTE) pathway goal, researchers at Oak Ridge National Laboratory performed an experimental investigation of the potential efficiency and emissions benefits of dual-fuel advanced combustion approaches on a modified heavy-duty 15-L Detroit™ DD15 engine. For this work, a natural gas port fuel injection system with an independent injection control for each cylinder was added to the DD15 engine. For the dual-fuel strategies investigated, 65%–90% of the total fuel energy was supplied through the added port fuel injection natural gas (NG) fueling system. The remaining fuel energy was supplied by one or more direct injections of diesel fuel using the production high pressure diesel fueling system. The production DD15 air handling system and combustion geometry were unmodified for this study. Efficiency and emissions with dual-fuel strategies including both low temperature combustion (LTC) and non-LTC approaches such as dual fuel direct-injection were investigated along with control authority over combustion phasing. Parametric studies of dual-fuel NG/diesel advanced combustion were conducted in order to experimentally investigate the potential of high-efficiency, dual-fuel combustion strategies to improve BTE in a multi-cylinder engine, understand the potential reductions in engine-out emissions, and characterize the range of combustion phasing controllability. Characterization of mode transitions from mixing-controlled diesel pilot ignition to kinetically controlled ignition is presented. Key findings from this study included a reproducible demonstration of BTE approaching 48% at up to a 13-bar brake mean effective pressure with significant reductions in engine-out NOx and soot emissions. Additional results from investigating load transients in dual-fuel mode and initial characterization of particle size distribution during dual-fuel operation are presented.