Internal Combustion Engine Applications Research Articles

Comparative study on ethyl butanoate reactivity – Experimental investigation and kinetic modeling of the C6 ethyl ester

Ethyl butanoate is a representative for oxygenated hydrocarbons as they are discussed as future liquid fuels from sustainable production pathways. An in-depth understanding of the influence of oxygen on the reactivity of those fuel candidates is mandatory for the molecular design and their application in internal combustion engines. Towards this goal, ignition delay times for ethyl butanoate were measured at conditions relevant to internal combustion engines using a shock tube and a rapid compression machine. These experiments were conducted for stoichiometric mixtures with air-like conditions at pressures of 20, 30 and 40 bar and a total temperature range of 680–1260 K. A negative temperature coefficient regime was found where the ignition delay times increased with increasing temperatures for all covered pressures. To further understand the kinetics of ethyl butanoate and the influence of the ester functional group, a detailed kinetic mechanism was developed and validated against the measured ignition delay times. A good agreement between the measured data and the prediction by the newly developed mechanism was achieved. The findings of this work were then used to compare ethyl butanoate to di-ethyl carbonate, methyl pentanoate and n-heptane, which also show a seven-heavy-atom-membered main chain and have all been kinetically studied before. The differences between the molecular structures and their effect on the kinetic pathways was discussed to extract information for future fuel design. It was found that especially the inhibting effect of oxgen atoms on six-membered internal H-atom migration reactions has a significant impact on the fuel’s reactivity.

Combustion behavior of ammonia blended with diethyl ether

Ammonia (NH3) is recognized as a carbon-free hydrogen-carrier fuel with a high content of hydrogen atoms per unit volume. Recently, ammonia has received increasing attention as a promising alternative fuel for internal combustion engine and gas turbine applications. However, the viability of ammonia fueling future combustion devices has several barriers to overcome. To overcome the challenge of its low reactivity, it is proposed to blend it with a high-reactivity fuel. In this work, we have investigated the combustion characteristics of ammonia/diethyl ether (NH3/DEE) blends using a rapid compression machine (RCM) and a constant volume spherical reactor (CVSR). Ignition delay times (IDTs) of NH3/DEE blends were measured using the RCM over a temperature range of 620 to 942 K, pressures near 20 and 40 bar, equivalence ratios (Φ) of 1 and 0.5, and a range of mole fractions of DEE, χDEE, from 0.05 to 0.2 (DEE/NH3 = 5 – 20%). Laminar burning velocities of NH3/DEE premixed flames were measured using the CVSR at 298 K, 1 bar, Φ of 0.9 to 1.3, and χDEE from 0.1 to 0.4. Our results indicate that DEE promotes the reactivity of fuel blends resulting in significant shortening of the ignition delay times of ammonia under RCM conditions. IDTs expectedly exhibited strong dependence on pressure and equivalence ratio for a given blend. Laminar burning velocity was found to increase with increasing fraction of DEE. The burnt gas Markstein length increased with equivalence ratio for χDEE = 0.1 as seen in NH3-air flames, while the opposite evolution of Markstein length was observed with Φ for 0.1 < χDEE ≤ 0.4, as observed in isooctane-air flames. A detailed chemical kinetics model was assembled to analyze and understand the combustion characteristics of NH3/DEE blends.

Study of flash boiling combustion with different fuel injection timings in an optical engine using digital image processing diagnostics

Flash boiling atomization is considered a potential solution to multiple issues encountered in fuel atomization for internal combustion engine applications. It has been demonstrated that flash boiling combustion can reduce soot emission under cold-start conditions, while the analysis was still preliminary and limited to engine cold-start conditions. This work investigates the performance of flash boiling combustion in comparison to sub-cooled spray combustions realized with the variation of injection timing. An optical engine facility was used to capture the combustion characteristics with a high-speed color camera, with the temperature of the engine coolant maintained at 60 °C. HSV color model and modified digital CH*/C2* ratio (excess air intensity) to study different flame regions and local combustion richness in the optical engine. The results show that under the conditions tested, flash boiling can improve the efficiency of the engine while reducing the PN emission simultaneously. Furthermore, it was seen that flash boiling combustion could yield a faster flame speed, uniform distribution of flames and less rich mixtures. Finally, color model analysis for transient and averaged flame images is also in good agreement with actual engine performance.

Fe-Al-Si Alloys for Applications in Internal Combustion Engines

Iron aluminides have been considered as materials resistant against high temperature oxidation in air and sulphur-containing environments. Previous research of our team proved that the oxidation resistance in the air can be significantly improved by the addition of silicon. Fe-Al-Si alloys have also very good mechanical properties at high temperatures. However, the resistance in the environments simulating combustion gasses have not been studied yet. This work focuses on the oxidation resistance in carbon dioxide, which is the main component of the combustion gasses. It was found that the Fe-Al-Si, Fe-Al-Si-Ni and Fe-Al-Si-Ti alloys have lower oxidation resistance in carbon dioxide containing atmosphere than in the air due to carbon diffusion to the material and even to the formation of carbides below the oxide layer. It leads to the spallation of the oxide layer, especially in FeAl20Si20Ni20 alloy.

Investigation on flash boiling spray fluctuations in the near-field and far-field under gasoline direct injection related conditions

Flash boiling spray has been considered as a promising atomization scheme in improving fuel-air mixture and reduce spray impingement in internal combustion engine applications. Because of its distinctive breakup mechanism, the thermal process of flash boiling spray has not been fully illustrated, in which the fluctuation of flash boiling sprays is not sufficiently studied. This work utilized a high-speed imaging system to implement Schlieren and backlit measurement, with a micro-lens to capture the near-field characteristics and a regular lens for macroscopic studies. A practical two-hole gasoline direction injection fuel injector was used, and the fuel temperature and ambient pressure were varied to generate different superheat indices. Image processing methods were used to find the variation of the center of mass in the spray image to quantify the fluctuation of the spray. Near-field and far-field spray fluctuations were studied systematically for the first time. The results show that near-field fluctuation is enhanced by flash boiling sprays, while far-field fluctuation of flash boiling sprays is suppressed, thus yielding a more stable overall spray cycle-to-cycle variation. The detailed breakup process of flash boiling sprays in the near-field is analyzed. The near-field cone angle and its uncertainty under various boundary conditions are investigated as well. Furthermore, the results have the potential to optimize the problems related to engine stability.

Experimental Investigation of Performance and Emissions of Ethanol and n-Butanol Fuel Blends in a Heavy-Duty Diesel Engine

Alcohol fuels are potential alternative fuels for low-temperature combustion concepts in internal combustion engine applications. In this work, 80 vol% of ethanol and 80 vol% of n-butanol are blended with 20 vol% of n-heptane, respectively. These two alcohol fuel blends are investigated in a combustion research unit and a single-cylinder heavy-duty engine to compare the combustion and emission characteristics. The effects of EGR rate and achievable operating load range when using ethanol and n-butanol are the major goals of this investigation. The results show that the ethanol fuel blend requires much higher temperatures to auto-ignite than do the n-butanol blend and diesel. Both alcohol fuel blends show negligible soot emissions in the medium load range when operated with a 40% EGR rate. However, the ethanol fuel blend produces more nucleation mode particles and fewer accumulation mode particles compared to the n-butanol fuel blend under the same operating condition. Furthermore, the particulate size distribution shows that diesel generates more particles with larger particle diameters and thus more soot mass compared to alcohol fuel blends. Still, both alcohol fuel blends can be operated from low to high load with simultaneous reduction of NOx and soot emissions but at the cost of increased HC and CO emissions. The Euro VI-regulated soot mass and particle number are achieved from low to medium-high load for alcohol fuels. Diesel has the great advantage of achieving high combustion efficiency but shows a NOx/soot tradeoff at a high EGR rate. Generally, the ethanol fuel blend yields the lowest gross indicated efficiency in the whole test range compared to diesel and the n-butanol fuel blend due to the necessity of inlet heating, which decreases the thermal efficiency. The n-butanol fuel blend achieves the highest gross indicated efficiency (above 50%) in the medium-high load range.

Stability Analysis of the Fluorescent Tracer 1-Methylnaphthalene for IC Engine Applications by Supercontinuum Laser Absorption Spectroscopy.

1-methylnaphthalene (1-MN) is a widely used laser-induced fluorescence (LIF) tracer for planar imaging of mixture formation and temperature distributions in internal combustion (IC) engines. As the LIF measurement results can be biased by partial tracer oxidation, the conversion of 1-MN and the base fuel isooctane is analyzed in a calibration cell. First, measurements using supercontinuum laser absorption spectroscopy (SCLAS) are presented in order to quantify the conversion by detection of the produced H2O mole fraction. A single mode fiber (SMF) coupled setup is presented, with the fiber core acting as entrance slit of a Czerny-Turner spectrometer. Dependencies on residence time and global air-fuel ratio are presented at pressures up to 1.5 MPa and temperatures up to 900 K, at which distinct tracer and fuel consumption is observed. Signal loss due to intense beam steering was partially compensated using a self-stabilizing double-pass setup with a retroreflector.

Fast Catalyst Light-Off with Dynamic Skip Fire

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Catalytic aftertreatment is commonly used to reduce regulated gas emissions from Internal Combustion (IC) engines. Achieving fast catalyst light-off has always been a challenge for automobile IC engine applications. This paper experimentally studied the thermal management and regulated gas emissions from a Spark Ignition (SI) engine with Dynamic Skip Fire (DSF®) technology during cold start period.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;The study has found that DSF can increase exhaust gas temperature at the catalyst inlet by up to 100°C, and the exhaust enthalpy by up to 20%. Cold start tailpipe carbon monoxide (CO) and hydrocarbon (HC) emissions can be reduced by 10% to 20% largely due to the increased exhaust gas temperature and enthalpy. Dynamic air pumping can further increase exhaust gas temperature by 30 °C, and can nearly double enthalpy delivered to the catalyst, which reduces cold start HC emissions by more than 50%.&lt;/div&gt;&lt;/div&gt;

Design and Numerical evaluation of crankshaft of diesel engine for total deformation and strain

The crankshaft is an engine component that converts the linear (reciprocating) motion of the piston into rotary motion. Features of a crankshaft include the crankpin journal, throw, bearing journals, counterweights, crank gear, and a power take-off (PTO). Crankshafts are machined through a sequence of automated operations that remove material using lathes and milling machines. Other off-the line processes include inspection, test and repair. High-count cylinder engines involve higher inertias, overlapping combustion events and torsional vibrations of the flexible crankshaft which strongly complicate the diagnostics. The equivalent inertias and stiffness’s of the system were calculated from drawings, modelling of the crankshaft with a CAD (computer-aided design) software and finite element method. Crankshaft is Internal cylinder pressure (or torque) estimation is an important engine parameter with significant implications for diagnostic and control applications in internal combustion (IC) engines. Many speed-based diagnostics methods employ models of the engine dynamics. In a dynamic model of a small four-cylinder diesel engine with the assumption of a rigid crankshaft is employed to estimate individual cylinder power production.

Experimental study on combustion characteristics of a CI engine runs on a renewable fuel

ABSTRACT Currently, the world is focusing on utilising biofuels as much as possible for internal combustion (IC) engine applications. Several strategies are being employed to improve fuel efficiency and decrease exhaust emissions of compression ignition (CI) engines which run on different biofuels. Fuel air mixture formation is one of the key aspects that influence engine behaviour in terms of combustion, emission, and performance of CI engines. In this research work, an attempt was made to induce air motion in a CI engine which was operated with an orange oil diesel (O-D) blend. For this purpose, a single cylinder, 4-stroke, air-cooled, direct injection (DI) diesel engine producing power of 4.4 kW at a constant speed of 1500 rpm was used. The piston of the engine was modified by two means to create turbulence; (i) piston with micro holes, and (ii) piston with micro holes and spiral grooves. The combustion characteristics of the test engine run on the O-D blend, without and with the change in piston geometries were evaluated, compared with the baseline diesel fuel operation, and presented in this paper.

Efficient simulation and auto-calibration of soot particle processes in Diesel engines

Parameters describing soot particle processes are generally derived from a limited number of experimental studies. These parameters then have to be carefully calibrated for different operating conditions in internal combustion engine applications. This paper presents an innovative calibration procedure for soot simulation in Diesel engines. A Diesel engine is simulated using the Stochastic Reactor Model engine code, which is implemented with the Moment Projection Method for handling the soot particle dynamics. The main advantage of the engine-soot model is its low computational cost. The model is then coupled with an advanced statistical toolkit, Model Development Suite, where the Hooke-Jeeves algorithm is adopted to calibrate seven soot model parameters automatically based on the measurement data. The ability of the integrated code for soot model calibration is evaluated by simulating the soot formation and oxidation processes in a heavy-duty Diesel engine which is operated under 18 different conditions. Results suggest that the integrated code is able to calibrate the soot model parameters effectively. A significant improvement in the match between the simulation results and experimental soot emission is obtained after calibration.

Performance study of the hypocycloid gear mechanism for internal combustion engine applications

Fuel conversion efficiency is one of the main concerns in the field of internal combustion engine systems. Although the Otto cycle delivers the maximum efficiency possible in theory, the kinematics of the slider–crank mechanism of the conventional internal combustion engines makes it difficult to reach this level of efficiency in practice. This study proposes using the unique hypocycloid gear mechanism instead of the conventional slider–crank mechanism for the internal combustion engines to increase engine efficiency and minimize frictional power losses. The hypocycloid gear mechanism engine’s kinematics provides the means for the piston-rod assembly to reciprocate in a straight-line motion along the cylinder axis besides achieving a nonlinear rate of piston movement. As a result, this characteristic allows for a true constant-volume combustion, which in turn would lead to higher work output. An in-cylinder gas volume change model of the hypocycloid gear mechanism engine was developed and incorporated into the thermodynamic model for the internal combustion engine cycle. The thermodynamic model of the hypocycloid gear mechanism engine was developed and simulated using MATLAB/Simulink software. A comparison between the conventional engine and the hypocycloid gear mechanism engine in terms of engine performance characteristics showed the enhancements achieved using hypocycloid gear mechanism for internal combustion engine applications. The hypocycloid gear mechanism engine analysis results indicated higher engine efficiency approaching that of the Otto cycle.

Tailoring the Temperature Sensitivity of Ignition Delay Times in Hot Spots Using Fuel Blends of Dimethyl Ether, Methane, and Hydrogen

Advanced combustion concepts based on autoignition of combustible mixture for internal combustion engine and gas turbine applications are sensitive to reactivity gradients arising from temperature ...

Application of Thermo-chemical Technologies for Conversion of Associated Gas in Diesel-Gas Turbine Installations for Oil and Gas Floating Units

Abstract The paper considers the issue of thermo-chemical recovery of engine’s waste heat and its further use for steam conversion of the associated gas for oil and gas floating units. The characteristics of the associated gas are presented, and problems of its application in dual-fuel medium-speed internal combustion engines are discussed. Various variants of combined diesel-gas turbine power plant with thermo-chemical heat recovery are analyzed. The heat of the gas turbine engine exhaust gas is utilized in a thermo-chemical reactor and a steam generator. The engines operate on synthesis gas, which is obtained as a result of steam conversion of the associated gas. Criteria for evaluating the effectiveness of the developed schemes are proposed. The results of mathematical modeling of processes in a 14.1 MW diesel-gas turbine power plant with waste heat recovery are presented. The effect of the steam/associated gas ratio on the efficiency criteria is analyzed. The obtained results indicate relatively high effectiveness of the scheme with separate high and low pressure thermo-chemical reactors for producing fuel gas for both gas turbine and internal combustion engines. The calculated efficiency of such a power plant for considered input parameters is 45.6%.

Production of biodiesel from Cordiamyxa bio-oil using BaMoO4-Ce2O3 nanoparticles as an alternative fuel for diesel engine

In recent years, the production of biodiesel has rapidly increased due to its benefits and to resolve the problem findings present in environmental pollution. In, this study barium salts doped with cerium oxide are used as a heterogeneous catalyst for the production of biodiesel from Cordiamyxa oil. The synthesized BaMoO4-Ce2O3 nanocatalyst has characterized by XRD (X-ray powder diffraction) and SEM (Scanning Electron Microscope) analysis. Methanol to a molar ratio of oil from 12:1 to 16:1 has studied and got the optimized results. An optimum yield of 87.50 wt% of methyl esters collected from Cordiamyxa bio-oil with optimized limits of 0.5 wt% of catalyst BaMoO4-Ce2O3 at 65 °C. The purpose of the current study investigates the analysis of biodiesel and their blends with diesel oil in four-stroke internal combustion engine (ICE) applications like unburned hydrocarbons, sulfates, particulate matter, polycyclic aromatic hydrocarbon, carbon monoxide, and nitrate aromatic hydrocarbons. Cordiamyxa methyl ester blend (Biodiesel-B20) with BaMoO4-Ce2O3 nanoparticles shows a better engine performance and emission reduced compared to fossil fuels like decrease hydrocarbon particulate matters.

Importance of Tribological study for Internal Combustion Engines using Biofuel

Biofuel applications in internal combustion engines have become a burning issue nowadays. This is because of the fact that fossil fuels have limited storage in the earth crust as well as for their polluting nature to the environment. For the last one decade or so, researchers are trying their level best to utilize different biofuels in engines. The selection of biofuel mainly depends on their availability, geographical location, climatic conditions etc. It has been found in the literature that researchers have given their utmost efforts to find out engine performances, combustion characteristics and emission characteristics using different biofuels. In some cases, it has been found a particular biofuel which satisfies most of the criteria in so far as performance or combustion or emission or combination of these to a considerable extent. But the earlier research did not include the lifespan of the engine components. The reduced lifespan due to utilizing higher viscous fuel in the engine is not economic at all if so happens. Therefore, it is required to make a new dimension of the research in terms of lifespan measurement of the vital parts of the engine operated by any biofuel. With a view to measuring lifespan, tribological studies have been highlighted in this present work. Finally, it has been concluded the importance of tribological parameters study in the context of IC engine research.

Numerical analysis of multiphase flow through axial vortex tube cyclone separators

Axial cyclone separators are used as primary filtration components in many internal combustion engine applications. A numerical study of gas-solid flow through an axial cyclone separator is carried out by Eulerian-Lagrangian CFD approach, which uses discrete phase modelling (DPM) of particles and solution of incompressible turbulent Navier-Stokes equations with RNG k—ɛ closure model. The effective filtration of inlet air from dust particles is an important requirement for prolonged engine life cycle. In axial cyclone separators, a helical swirl generator is used for imparting swirling motion to theparticle laden flow and particles are filtered by centrifugal separation and then scavenged using a vortex tube. In the present work, the modelling done in OpenFOAM successfully captures the features of the swirling flow, along with particle–gas and particle–wall interactions for a varying size distribution at the inlet. Studies were aimed at analysing the effect of particles and its effect on improving the performance of the filter.

Methane number measurements of hydrogen/carbon monoxide mixtures diluted with carbon dioxide for syngas spark ignited internal combustion engine applications

A comprehensive analysis of the autoignition tendency of binary mixtures of hydrogen and carbon monoxide diluted with carbon dioxide is carried out in this paper. Methane Number (MN) measurements of these mixtures were performed by using a method analogous to the standard method for Octane Number (ON) measurement. The experimental MNs ranged from 46.0 to 139.1 according to experimental data. These results are compared with the MNs calculated by programs released for natural gas MN estimations. A comparative analysis concluded that these programs are not suitable to calculate MN of syngas. A method to isolate the effect of carbon dioxide on the autoignition tendency of binary mixtures of hydrogen and carbon monoxide is proposed. Results reveal that increments of carbon dioxide concentration in the mixtures, exponentially increase the MN of the mixtures. At low carbon dioxide concentration, the MN of the ternary mixtures can be approximated by the MN of their equivalent binary mixtures of hydrogen and carbon monoxide. Based on this observation, the MNs of coal gases reported in the literature are estimated.

Mechanical efficiency prediction methodology of the hypocycloid gear mechanism for internal combustion engine application

Mechanical friction power loss is one of the main concerns in the internal combustion engine (ICE) systems. The piston-rod assembly and the complex motion of the connecting rod are the largest source of engine friction. A significant reduction in these losses can be achieved with ICE systems incorporating the hypocycloid gear mechanism (HGM), which ensures that the piston-rod assembly reciprocates in a perfect straight-line motion along the cylinder axis to eliminate the piston side load. This paper investigates the feasibility of an enhanced HGM for the design and development of ICE applications. It incorporates designing the planetary crank gearing system to satisfy the design specifications of ICE using the standard design procedures provided by AGMA. This is followed by building the friction model for the interacting components of the HGM engine through developing the mathematical model for the friction power loss of the internal gear train meshes, rolling bearings, and sliding bearings. The total friction power losses of the HGM engine are calculated and compared with the friction model of the conventional crank-slider engine that has been developed by Sandoval and Heywood (An Improved Friction Model for Spark-Ignition Engines. SAE Technical Paper 2003-01-0725, 2003). The comparison results show the feasibility of using the HGM for ICE applications with minimized engine friction power losses and hence higher mechanical efficiency.

Toward the accurate prediction of soot in engine applications

Soot emissions from internal combustion engines represent a major challenge to engine manufactures with ever most stringent emission regulations, not only in soot mass yielded but also in soot particle number. For example, a particulate number standard has been introduced in 2011 with Euro 5b for diesel engines and in 2014 with Euro 6 for petrol engines (a limit of 6 × 1011/km). Soot models provide a detailed insight into soot evolution processes and are thus an essential tool in today’s advanced engine designs. Therefore, continuous efforts are made to develop more physically based engine soot models and improve the prediction accuracy. The primary objective of this work is to identify and demonstrate the critical parameters for accurate soot predictions in internal combustion engine applications using the high-fidelity detailed soot model from an engineering point of view. A detailed soot model based on sectional method was used to solve the soot process in diesel and spark ignition direct injection gasoline engines. A series of sensitivity analyses were carried out to evaluate the importance and significance of wall boundary conditions, wall film formation and vaporization, multi-component fuel surrogate, and soot transport process in engine exhaust on soot predictions. The predicted results were compared in details to engine-out measurements in terms of soot mass, number density, and size distributions under various operating conditions. The model results demonstrate that the correct description of the spray–wall interaction and wall film vaporization, as well as the soot transport processes in full engine cycle, is critical for achieving reliable predictive capabilities in engine simulations, especially for spark ignition direct injection gasoline engines. The findings should help engineers in this field for more accurate soot predictions in engine simulations.