Direct Fuel Injection Research Articles

Combustion Characteristic Prediction of Dual Direct Injection Fuel (Diesel-Propane) on RCEM Based on an Artificial Neural Network Approach

Studies from around the world show that engines using biofuel, LPG, and CNG emit fewer pollutants than those using conventional fuels. Experimental research has focused on a rapid compression and expansion machine (RCEM) that resembles a compression ignition (CI) engine. It uses dual direct injection fuel, diesel and propane (DP), with propane injection timing varying from 0 to 40 before top dead center (BTDC) and diesel injection timing remaining at 10 BTDC. The compression ratio was changed at points 17 and 19 by adjusting the RCEM connecting rod. A converge simulation program was used to run the simulation model, which was used to examine how the fire and inflow inside the chamber developed. The ANN method was used to predict pressure, temperature, power, TKE, and ITE data output based on propane energy fraction, compression ratio, and SOI of propane as input data parameters. It was noticed that the ANN prediction on experimental data has a higher accuracy compared to the simulation prediction. The R and MSE values were used to identify the accuracy of the prediction on output parameter data. ANN generalization capability is comparatively high when trained with large enough databases. The highest accuracy of prediction was produced on TKE, which had an MSE of 0.003715 and R value of 0.99981 from 287900 sample data. This shows that the ANN model is quite accurate in forecasting output experimental data.

Experimental Investigation on CO2 Emission Characteristics of Modified SI-Engine with Direct Fuel Injection (DFI) Technique

Experimental Investigation on CO2 Emission Characteristics of Modified SI-Engine with Direct Fuel Injection (DFI) Technique

Definition and evaluation of the gas exchange process of a two-stroke engine with external and internal mixture formation

Problem. The transition from external to internal mixture formation requires adjusting the organization of gas exchange processes. The subject of the research is the gas exchange indicators of the 1D 8.2/8.7 engine with spark ignition with a carburetor and direct fuel injection (DFI) for the organization of stratified fuel-air charge (SFAC) and stratified weak fuel-air charge (SWFAC). Goal. The purpose of research is to determine ways to improve cylinder cleaning from combustion products and increasing its filling with fresh charge at DFI. Methodology: the following methods were used to conduct a study of the engine according to the load characteristic (n = 3000 min-1) and determine the gas exchange indicators by the coefficients: consumption μ of the purge and exhaust channels; purge air leakage υ; residual gases γ; excess purge air φо; filling ηv; purging φ; use of purge air ηв; k.k.d. purge ηs. Originality. The empirical dependences of changes in gas exchange indicators: μ, υ, γ, φ, ηv on the load were determined. Results. With a carburetor power system γ = 0.24-0.17, φo = 0.32-0.67 (bmep = 0.174-0.45 MPa). At the maximum load (bmep = 0.45 MPa) ηv = 0.5. The use of a hemispherical symmetric combustion chamber with an increase in volume and load creates conditions for reducing γ and increasing ηs to 0.86. With DFI and the organization of the SFAC γ = 0.15-0.13 (bmep = 0.21-0.45 MPa), SWFAC γ = 0.16-0.13 (bmep = 0.144-0.21 MPa), γ = 0.4 (bmep = 0.43 MPa). In the case of SFAC and SWFAC, the maximum values of φо = 0.7 and ηv = 0.52 (bmep = 0.42–0.44 MPa). As the load decreases, the values of φо and ηv from the SWFAC exceed the values from the SFAC by up to 9%. The largest values of ηs = 0.87-0.88 (bmep = 0.21-0.47 MPa) correspond to the SFAC and the hemispherical combustion chamber shifted to the exhaust window. The organization of SWFAC in a hemispherical symmetric combustion chamber of smaller volume contributes to the reduction of ηs from 0.875 to 0.71. Practical value. In order to reduce γ and increase ηv at SWFAC, it is necessary to direct the flow of purge air inside the combustion chamber by installing an additional purge channel opposite the exhaust window.

Model-free control applied to a direct injection system: Experimental validation

This work presents the design and application of the Model-free controller with algebraic estimator and ultra-local model on the common-rail high-pressure in a Direct Injection Fuel System of an internal combustion engine. In this application, the PID controller is traditionally used, but it needs different settings as modifications in the operating point occur. These changes encompass motor rotation, injection time, or torque demand. On the other hand, this paper considers only a single set of control parameters that provides good performance considering a broad range of operating points. A commercial electronic control unit (FlexECU) offering the possibility of new software development was used to implement the control algorithm and manage all engine functions. The tuning process of the controller is presented and discussed. Tests were carried out, and the results were graphically demonstrated, evidencing the easy applicability, robustness, and ability of the considered Mode-free scheme to control nonlinear systems, even facing important dynamic variations.

Evaluation and Simulation Analysis of Mixing Performance for Gas Fuel Direct Injection Engine under Multiple Working Conditions

Gas fuel direct injection (DI) technology can improve the control precision of the in-cylinder mixing and combustion process and effectively avoid volumetric efficiency reduction in a compressed natural gas (CNG) engine, which has been a tendency. However, compared with the port fuel injection (PFI) method, the former’s mixing path and duration are shortened greatly, which often leads to poor mixing uniformity. What is worse, the in-cylinder mixing performance would be seriously affected by engine working conditions, such as engine speed and load. Based on this situation, the fluid mechanics software FLUENT is used in this article, and the computational fluid dynamics (CFD) model of the injection and mixing process in a gas-fueled direct injection engine is established. A quantitative evaluation mechanism of the in-cylinder mixing performance of the CNG engine is proposed to explore the influencing rule of different engine speeds and loads on the mixing process and performance. The results indicate that phase space analysis can accurately reflect the characteristics of the mixture mixing process. The gas fuel mixture rapidly occupies the cylinder volume in the injection stage. During the transition stage, the gas fuel mixture is in a highly transient state. The diffusion stage is characterized by the continuous homogenization of the mixture. The in-cylinder mixing performance is linearly dependent on the engine’s working condition in the phase space.

Experimental Investigation of the Biodiesel Direct Injection and Diesel Fuel as Premixed Charge on CI-Engine Emissions, Performance, and Combustion Characteristics

This study aims to investigate the use of waste cooking oil biodiesel blend (B30D70) in CDC mode and the use of different premixing ratios of diesel vapor (15%, 20%, 25% and 30%) through manifold injection at a manifold premixed temperature of 110 ⁰C in PCCI mode when using biodiesel blend (B30D70) as the main fuel and diesel as the premixed fuel. The experiments were carried out on 4-stroke, single-cylinder, air cooled, DI diesel engine which was modified to run in PCCI mode with adding a fuel vaporizer to create the external homogeneous mixture. The engine combustion parameters, performance, and emissions characteristics were fully discussed, and the results were compared with these of CDC mode fueled by diesel. The obtained results for the use of B30D70 fuel indicates a certain decrement for exhaust gas temperature, HC, and CO emissions, but with a penalty in brake thermal efficiency, NOx, and smoke opacity. The experiments revealed that the best results were indicated for 20% diesel vapor in PCCI mode as CO, HC, NOx, and EGT reduced by 34.62%, 43.75%, 2.65% and 8.53% respectively and almost has the same BTE compared to CDC mode fueled by diesel. While increasing PR to 25% and 30% decrease the volumetric efficiency leads to rich mixture and deterioration of combustion and increase CO, HC and smoke emissions.

Study of Scavenging and Combustion Processes for Small Two-Stroke Aviation Heavy Fuel Direct Injection Engines

Heavy-fuel aviation piston engines (HF-APEs) are widely used in general aviation and unmanned aerial vehicle (UAV) due to their safety and fuel economy. This paper describes a numerical and experimental study of scavenging and combustion processes on a 2-Stroke Direct Injected HF-APEs for light aircraft, with its cylinder specifically designed as cross scavenging. A 3-Dimentional transient model of in-cylinder flow and combustion process is established by the Forte platform, and the engine test system is set up. By comparing the simulation results to the experimental results, it showed that multi-ports cross scavenging can generate unbalanced aerodynamic torque in the cylinder. In the compression process, the swirl ratio (SR) gradually increases, and the peak SR reaches 15. Moreover, approximately 25% of exhaust residual gas in the cylinder is conducive to the fuel atomization and evaporation process in a high-altitude environment. When the injection timing is between −8 °CA and −16 °CA, the engine has the optimal power and economy performance at different altitudes. Finally, when the injection advance angle moves forward by 4 °CA, the maximum pressure increases by 2 MPa, with the rising rate decreasing gradually. The results have important significance for the development of the combustion system of small 2-Stroke Direct Injected HF-APEs.

Combined Effect of Start of Direct Injection Timing and Fuel Temperature on Combustion and Pollutant Emissions of a Reactivity Controlled Compression Ignition Operated Single-Cylinder Diesel Engine

Combined Effect of Start of Direct Injection Timing and Fuel Temperature on Combustion and Pollutant Emissions of a Reactivity Controlled Compression Ignition Operated Single-Cylinder Diesel Engine

Co-optimizing Engine Hardware and Fuel Chemistry for Improving Thermal Efficiency and Reducing Pollutant Emissions of Gasoline Fueled Direct Injection Internal Combustion Engines

Co-optimizing Engine Hardware and Fuel Chemistry for Improving Thermal Efficiency and Reducing Pollutant Emissions of Gasoline Fueled Direct Injection Internal Combustion Engines

Numerical Comparative Study on the In-Cylinder Mixing Performance of Port Fuel Injection and Direct Injection Gas-Fueled Engine

In recent decades, research on alternative fuel engines is becoming more and more popular. Compressed natural gas (CNG) has the advantages of abundant reserves and a lower cost. It can reduce vehicle emissions relatively quickly and has little impact on the entire transportation infrastructure. As the fourth generation of a gas fuel supply method, gas fuel direct injection (DI) technology can effectively avoid volumetric efficiency reduction and power reduction problems of the port fuel injection (PFI) method. However, the former’s mixing path and duration are shortened greatly, which often leads to poor mixing uniformity. In order to improve the in-cylinder mixing uniformity, the in-cylinder mixing process of the CNG-fueled engine is taken as the research object in this study. The computational fluid dynamics (CFDs) models of the mixing process for the PFI and DI modes are established, and their mixing uniformities are compared. Besides, based on the authors’ previous research, the influence mechanism of the piston crown shape and fuel injection angle on the mixing process of the CNG DI engine is explored. The results show that the probability distribution frequency (PDF) of the best mixture concentration region (BMCR) is as high as 72% for the PFI mode, which is much higher than for the DI mode. The shorter jet impingement distance of the flat top piston leads to higher turbulent kinetic energy (TKE) intensity, and the in-cylinder mixing uniformity will be improved. When gas fuel is injected into an area with a higher in-cylinder TKE, the average in-cylinder TKE will be higher, and the in-cylinder mixture will be more homogeneous.

Approaches for emission reduction in natural gas fueled direct-injection engines

A glow plug (GP) can serve as an effective ignition source in a heavy-duty direct-injection natural gas (DING) engine. Ignition performance can be improved by shielding the GP. The shield protects the GP from cooling by the injected natural gas (NG) jets and also traps NG next to the GP surface, acting as kind of pre-combustion chamber. Achieving rapid filing of the shield by a fuel jet and facilitating flame propagation out are key goals of shield design. However, previous studies found that emissions such as unburned CH4 and soot particles could be trapped inside the shield especially near its top end, contributing a large fraction to the engine exhaust. In this paper, new designs either controlling the NG amount entering the shield or improving the emission propagation out of the shield are proposed to solve the emission issues, and the impacts of these design changes on fuel injection and combustion emissions were computationally investigated. The base case includes an injector with nine 0.2 mm diameter nozzles and a diamond-pattern multi-opening GP shield. A new injector combining one smaller nozzle directed towards the GP shield and eight regular size nozzles was compared, while a new five-opening shield design adding a small opening on the top end of the diamond-pattern shield was studied. Compared to the base case, the new two-nozzle-size injector greatly reduced the amount of fuel injected into the shield, which solved the emission issues inside the shield. Over 35% and 95% reductions in the total mass of unburned CH4 and soot particles respectively were achieved. Furthermore, the additional opening for the new shield provides an alternative route for fuel flowing out of the shield during fuel injection. However, fuel injection is the main force for fuel motion inside the shield and highly affects the new flow route provided by the additional opening. The unburned CH4 and formed soot particles could not flow out of the shield through the additional opening once fuel injection is finished. Generally, an increase was found for the unburned CH4 and soot mass by using the new five-opening shield, compared to the base case.

Heat Transfer and Residence Time in Lean Direct Injection Fuel Galleries

Abstract In radially staged lean direct injection (LDI) systems, pilot fuel plays an important role in cooling the mains fuel gallery in regions of the flight envelope where the mains fuel is stagnant. Under these conditions, managing wetted wall temperatures is vital to avoid the formation of carbonaceous particles, which become deposited on the surfaces of the fuel gallery and can lead to a deterioration in system performance. The prediction of wetted wall temperatures therefore represents an important aspect of the injector design phase. Such predictions are often based on injector thermal models, which tend to rely on the application of convective boundary conditions from empirical heat transfer correlations. The use of these correlations leads to questions over the accuracy of predicted wetted wall temperatures and therefore uncertainty over the probability of deposition. This paper seeks to improve on the current situation by applying the inverse conduction technique to determine heat transfer coefficients (HTCs) specific to the pilot fuel gallery. These HTCs are crucial for determining wetted wall temperatures in the pilot and mains fuel galleries and principally govern the risk of deposition in the stagnant mains. The pilot heat transfer data are further examined alongside measurements of the pilot residence time distribution, which together control the risk of pilot deposition at low fuel flow rates. Both the heat transfer and residence time measurements demonstrate the opportunity for future fuel gallery design refinement and provide the supporting data to facilitate this.

Detailed Analysis of the Effects of Biodiesel Fraction Increase on the Combustion Stability and Characteristics of a Reactivity-Controlled Compression Ignition Diesel-Biodiesel/Natural Gas Engine

A single-cylinder marine diesel engine was modified to be operated in reactivity controlled compression ignition (RCCI) combustion mode. The engine fueling system was upgraded to a common rail fuel injection system. Natural gas (NG) was used as port fuel injection, and a diesel/sunflower methyl ester biodiesel mixture was used for direct fuel injection. The fraction of biodiesel in the direct fuel injection was changed from 0% (B0; 0% biodiesel and 100% diesel) to 5% (B5) and 20% (B20) while keeping the total energy input into the engine constant. The objective was to understand the impacts of the increased biodiesel fraction on the combustion characteristics and stability, emissions, and knocking/misfiring behavior, keeping all other influential parameters constant. The results showed that nitrogen oxides (NOx) emissions of B5 and B20 without the need for any after-treatment devices were lower than the NOx emission limit of the Euro VI stationary engine regulation. B5 and B20 NOx emissions decreased by more than 70% compared to the baseline. Significantly more unburned hydrocarbons (UHCs) and carbon monoxide (CO) emissions were produced when biodiesel was used in the direct fuel injection (DFI). The results also showed that using B5 and B20 instead of B0 led to an increase of 18% and 13.5% in UHCs and an increase of 88.5% and 97% in CO emissions, respectively. Increasing the biodiesel fraction to B5 and B20 reduced the maximum in-cylinder pressure by 3% and 10.2%, respectively, compared to B0. Combustion instability is characterized by the coefficient of variation (COV) of the indicated mean effective pressure (IMEP), which was measured as 4.2% for B5 and 4.8% for B20 compared to 1.8% for B0. Therefore, using B20 and B5 resulted in up to 34.9% combustion instabilities, and 18.5% compared to the baseline case. The tendency for knocking decreased from 13.7% for B0 to 4.3% for B20. The baseline case (B0) had no misfiring cycle. The B5 case had some misfiring cycles, but no knocking cycle was observed. Moreover, the historical cyclic analysis showed more data dispersions when the biodiesel fraction increased in DFI. This study shows the potential of biodiesel replacement in NG/diesel RCCI combustion engines. This study shows that biodiesel can be used to effectively reduce NOx emissions and the knocking intensity of RCCI combustion. However, combustion instability needs to be monitored.

Methane Slip Reduction of Conventional Dual-Fuel Natural Gas Diesel Engine Using Direct Fuel Injection Management and Alternative Combustion Modes

Methane Slip Reduction of Conventional Dual-Fuel Natural Gas Diesel Engine Using Direct Fuel Injection Management and Alternative Combustion Modes

Impact of additives on Combustion, performance and exhaust emission of biodiesel fueled direct injection diesel engine

The world is facing serious problem due to growing demand of fossil fuel and. The continuously rise in the price of crude oil and its features of producing harmful emissions results severe air pollution. The use of alternative fuels specially fuel derived through biomass would help to reduce the emissions of greenhouse gases (GHG). Biodiesel has emerged one of the potential alternative fuels to diesel. Biodiesel has several advantages, but few challenges such as high viscosity, low heating value, high level of nitric oxides emissions etc. The effect of using additives with biodiesel has a significant effect on its behaviour. There are wide range of additives such as metal-based additives, antioxidants, cetane improvers, and oxygenated additives etc. are used to improve the different characteristics of biodiesel. To minimise the pollutants and enhance the combustion and performance characteristics of the engine many efforts have been done. The current work discusses about application of additives in biodiesel to enhance its behaviour. The current study concluded that use of additives in biodiesel can be a vital solution to improve combustion, performance, and emission characteristics of engine.

Design and Experiment of a Prototype Electronic Control Unit Direct Injection Fuel System Arduino-Based for 2-stroke Spark Ignition Engine

The development of technology on the 2-stroke direct-injection spark-ignition engine is expected to be a solution to optimize engine performance and reduce exhaust pollution. The fuel injection system in the operation of the spark-ignition engine is controlled by the Electronic Control Unit (ECU), so this study aims to design and experiment with a prototype of an Arduino-based direct injection fuel injection electronic control unit for 2-stroke spark-ignition engines. This research method begins with the design of an electronic control unit prototype that is selected for easy setup and low cost. Then, experiments were conducted on variations in injection timing and injection duration, which are the two main parameters of the fuel system to determine their effect on engine performance. This data is then used as a basis for setting the amount of fuel injected. The results show that there is an optimal performance under certain conditions from setting the injection timing and injection duration which is easily applied to the open-source code setting of this electronic control unit.

A Statistical and Computational Predictive Model of the Direct Fuel Injection System in Diesel Engines

In recent years, the high emission standards have grown the development of different strategies focused on the reduction of pollutants produced by combustion processes in energy transfer systems. For that reason, different studies have been developed to minimize fuel consumption and elevate internal combustion performance under different operating modes. Internal combustion engines are widely studied currently by means of advanced theories of thermal and fluid mechanics sciences with the aim to improve the energy transfer processes needed to transform the chemical energy generated in work during the complex fuel combustion process into the combustion chamber. Inexpensive methods have been developed to improve the internal combustion engine performance based on the understanding of chemical reactions and physical processes of mass and energy transfer. Mathematical and experimental models are employed to approximate the real working conditions, the physical phenomenon of the fuel flow injected into the combustion chamber of the internal combustion engine. Therefore, this paper proposes a predictive model that relates the fuel injection system with the combustion process and the heat transfer into the walls of the combustion chamber. External forces are considered during the internal combustion engine operation under real working conditions taking into account the dependent variables of the partial differential equations system that describes the internal combustion engine performance. A good agreement was reached between the experimental and predictive approaches. The results showed an error rate of less than 3 percent, considering a multiple linear regression model adjusted to the characterized internal combustion engine.

Time-Resolved Endoscopic Evaluation of Spatial Temperature and Soot Distribution in a Butanol-Diesel Blend Fueled Direct Injection Compression Ignition Engine

Abstract In situ spatial soot and temperature distributions were investigated experimentally for B20 (20% v/v butanol and balance mineral diesel blend) vis-a-vis mineral diesel using endoscopic visualization technique. Endoscope captured the in-cylinder combustion images in a production-grade direct injection compression ignition (DICI) engine at varying engine operating conditions. A comparative combustion data analysis using pressure-crank angle history and the captured endoscopic images was performed. An attempt was made to correlate the results of these two experimental investigations. Combustion duration (CD) obtained from the endoscopic images was relatively longer than the CD calculated from the thermodynamic analysis. Most research on soot and NOx emitted from the engine using a raw exhaust gas emission analyzer provides bulk, time-averaged, and cycle-averaged information about the pollutant formation. This investigation is unique wherein the spatial or time-resolved soot and NOx formation (Via spatial temperature distribution) are evaluated. The findings of this study support the research finding available in the open literature using an emission analyzer. This study and the technique therein on the deployment of engine endoscopy as an emerging optical technique is potentially useful to original automotive manufacturers (OEMs) in designing more efficient engines, capable of meeting upcoming stringent emission norms.

Experimental and Numerical Analysis on the Influences of Direct Fuel Injection Into Oxygen-Depleted Environment of a Homogeneous Charge Compression Ignition Engine

Abstract The oxygen-depleted environment in the recompression stroke can convert gasoline fuel into light hydrocarbons due to thermal cracking, partial oxidation, and water-gas shift reactions. These reformate species can influence the combustion characteristics of gasoline direct injection homogeneous charge compression ignition (GDI-HCCI) engines. In this work, the combustion phenomena are investigated using a single-cylinder research engine under a medium load. The main combustion phases are experimentally advanced by direct fuel injection into the negative valve overlap (NVO) compared with that of intake stroke under single/double-pulse injections. NVO peak in-cylinder pressures are lower than that of motoring due to the limited O2 concentration, emphasizing that endothermic reactions occur during the overlap. This phenomenon limits the oxidation reactions, and the thermal effect is not pronounced. The zero-dimensional chemical kinetics results present the same increasing tendencies of classical reformed species of rich mixture such as C3H6, C2H4, CH4, CO, and H2 as functions of injection timings. Predicted ignition delays are shortened due to the additions of these reformed species. The influences of the reformates on the main combustion are confirmed by three-dimensional computational fluid dynamics (CFD) calculations, and the results show that OH radicals are advanced under NVO injections relative to intake stroke injections. Consequently, earlier heat release and cylinder pressure are noticeable. Parametric studies on the effects of injection pressure, double-pulse injection, and equivalence ratio on the combustion and emissions are also discussed experimentally.

Characterization of the emission of particles larger than 10 nm in the exhaust of modern gasoline and CNG light duty vehicles

Current particle number (PN) emission limits set by regulation, involve counted particles with a dimension >23 nm. The measurement procedure is specified and involves the dilution of the exhaust gas in a so-called constant volume sampling (CVS) device. Research efforts are concentrating in the further development of existing measurement techniques in order to capture smaller particles down to 10 nm, given their higher health threatening potential.In the present study, six state of art, Euro 6, gasoline vehicles and in addition, one compressed natural gas (CNG) light duty vehicle, have been measured on the chassis dynamometer during different test cycles. Three particle sampling lines have been used, two in parallel at the CVS, counting particles >23 nm and 10 nm, and a third one directly at the tailpipe of the vehicle. The results allow a detailed evaluation of the emitted PNs. In addition, differences in the emissions patterns of the direct fuel injection (DI) and multi point port injection (MPI) gasoline vehicles could be identified. During cold starts, particles have been separated in distinctive size classes in order to obtain relevant number-size distributions.Counting particles >10 nm resulted in roughly doubling the PN emissions in respect to those when counting particles >23 nm. This relation holds for all examined driving cycles. PNs measured at the CVS where significantly higher than at the tailpipe, especially when capturing also the smaller particles. The CVS could be identified contributing to the increase of the registered particle numbers during cycle parts with no or very low engine particle emissions.Lowest PN emissions have been measured in combination with the CNG vehicle. The differences between DI and MPI gasoline vehicles have been significantly lower than expected from previous studies. While the MPI gasoline vehicles have been identified to emit more PN during cold start, the DI vehicles emit larger numbers during high engine loads. During cold starts, higher emissions of smallest particles have been evident.The increased rated power to displacement ratio of modern engines, based on the current “downsizing” trend, shows a good correlation with the PN emissions.