Search

The thermal barrier coating method is applied using materials with low thermal conductivity to increase the efficiency and improve the emissions of internal combustion engines. However, coated surfaces may be damaged due to the high thermal and pressure stresses encountered by the piston surface in the combustion chamber during engine operation. In this study, experiments and analysis were carried out for four piston models to analyze the coating layer and increase its strength: two partially coated piston surface models, a fully coated model, and an uncoated piston model. The results of the transient thermal analysis revealed that the fully coated piston model exhibited the highest surface temperature. Additionally, heat losses were observed to be lower in the fully coated model compared to the other piston models. Partially coated piston models exhibited lower heat flux on the coated surface but higher heat flux on the uncoated combustion chamber surfaces. Combustion analysis indicated that the fully coated piston model exhibited the highest in-cylinder temperature and pressure values, while the uncoated model had the lowest values. When comparing heat transfer rates on the walls, the uncoated piston model exhibited the highest transfer, whereas the fully coated piston model exhibited the lowest. Finally, the fully coated piston demonstrated the highest combustion efficiency. [ABSTRACT FROM AUTHOR]

This study focuses on a four-cylinder, four-stroke hydrogen engine equipped with a passive pre-chamber (PC). The effects of excess air ratio (λ) on the performance of the turbulent jet ignition (TJI) hydrogen engine are investigated through experimental and numerical simulations. The hydrogen engine operates at 1600 rpm with an intake manifold pressure of 70 kPa. The results show that λ values significantly influence the internal flow field, energy distribution, and flame development in the PC, affecting the combustion in the main chamber (MC). The experiment found that as λ decreases, the BMEP and BTE gradually increase. Due to the influence of jet and multi-point ignition, the heat transfer loss in lean combustion is also relatively high. The jet oscillation caused by the TJI hydrogen engine has high controllability and low destructiveness, and λ is one of the main factors controlling the jet oscillation. The influence of spark timing (ST) on engine performance is explored through experiments. The results show that as λ increases, the sensitivity of BMEP to ST gradually decreases. With the delay of ST, BTE increased first and then decreased. However, the cyclic variation is less affected by ST. For the TJI hydrogen engine, an appropriate delay in ST under the close stoichiometric ratio condition can not only ensure power output and combustion stability but also reduce emissions. [Display omitted] • Pre-chamber gas-flow movement, mixture distribution, and flame propagation are analyzed • The pre-chamber exhibits stratification of the mixture under lean combustion conditions. • The BMEP and BTE continue to decrease with the increase of lambda. • The jet oscillations in TJI engines are highly sensitive to the excess air ratio. • The spark timing has a smaller effect on lean combustion than rich mixtures. [ABSTRACT FROM AUTHOR]

Supercharging is very efficient to improve thermal efficiency and reduce emissions of diesel engines. Especially, electrical supercharger development has significantly progressed in recent years and it enables high supercharging pressure operation which could not be realized by conventional turbo engines. However, it is suggested that excessive supercharging has a negative impact on indicated thermal efficiency by zero-dimensional combustion simulation. In this study, verification experiments using a single cylinder test engine were carried out to confirm the decrease of thermal efficiency by excessive supercharging arise. Furthermore, the configuration of superchargers was investigated to realize the best excess air ratio condition on the test engine. [ABSTRACT FROM AUTHOR]

Hydrocarbons with blending octane number (BON) higher than the octane number (ON) measured as a single component fuel are considered to have a large effect on improving the octane number of the mixed fuel when mixed with other hydrocarbons. In this study, the characteristics of the reaction of high BON hydrocarbons in mixed fuel were discussed based on the analysis of reaction products in a flow reactor. When mixed with primary reference fuels, hydrocarbons whose BON is higher than ON suppress the reaction of the mixture. This effect may be caused by the production of reaction intermediates at lower temperatures than when used as a single component fuel, or by the production of reaction intermediates that were not observed when used as a single component fuel. [ABSTRACT FROM AUTHOR]

Hydrogen has combustion characteristics such as a wide flammable range, fast burning velocity and low minimum ignition energy. The objective of this study is to reduce cooling losses and improve brake thermal efficiency due to hydrogen addition using a PI system SI engine in which hydrogen is injected into the intake pipe. This paper investigates the effects of rapid combustion by the PI system on combustion and exhaust characteristics. The results show that brake thermal efficiency increases with increasing hydrogen addition ratio, but cooling losses increase at higher hydrogen addition ratios. [ABSTRACT FROM AUTHOR]

Improving the thermal efficiency of gasoline automobile engines is a very important issue as a measure against global warming. For that purpose, we need to optimize the gasoline fuel so that the high engine performance can be fully exhibited. In the present study, the ignition delay times of new gasoline candidates containing light olefins were measured using a high-pressure shock tube, and both their knock resistance and lean-limit expansion were evaluated. The fuel performances of oxygenated hydrocarbons such as ethanol and ETBE for biofuels were also examined and their chemical effects in new gasoline candidates were discussed. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current work focuses on the usage of a sustainable fuel derived from Senna auriculata seed through pyrolysis for IC engine applications. Batch-type reactor was employed to produce the bio-oil through pyrolysis, and it was found that the optimum temperature of 550 °C is suitable for a maximum yield of 46%. Physical characterization of the produced SA oil is examined as per ASTM standards, and chemical characterization is studied using FTIR, 1HNMR, and GC–MS analysis to study and compare with conventional diesel. The performance of the engine, along with combustion and emission analysis, was carried out with blends of SA and diesel. The results investigated were compared with those of conventional diesel. The efficiency for the SA10 blend was estimated to be 34.5%, which is 1.27% higher than regular diesel fuel under full-load conditions. Emission analysis portrayed the CO and UHC emissions as low, whereas the increase in NOX emissions was due to the high temperature inside the cylinder and the presence of oxygen. The SA10 blends exhibited comparable performance and emission results with commercial diesel fuel under normal working conditions. This research provides an integrated approach to selecting the precise biomass and establishing sustainable bioenergy recovery as the future energy resolution. [ABSTRACT FROM AUTHOR]

Hydrocarbons with higher blending octane number compared to octane number may have a higher antiknock effect for multi components fuel in comparison with the effect predicted from octane number as a single component. In this study, the antiknock effect of isooctane, 4-octyne and 2,3-dimethyl-2-butene for multi components fuels were discussed based on the analysis of reaction products in a flow reactor. As a result, it was suggested that low temperature oxidation reactions of n-heptane promote oxidation reaction of these hydrocarbons. In addition, it was suggested that reaction products from hydrocarbons with high blending octane number such as 4-octyne and 2,3-dimethyl-2-butene inhibit chain reactions by consuming radicals produced from the low temperature oxidation reaction of n-heptane. [ABSTRACT FROM AUTHOR]

There is still a great need to enhance the thermal efficiency of automobile engines in order to achieve a sustainable society. The Atkinson cycle is an effective method for thermal efficiency enhancement. The Atkinson cycle is more complex than the conventional mechanism, but this complexity leads to a greater degree of freedom in the piston stroke characteristics. The stroke characteristics include the duration of each stroke and the speed of the piston, which affect thermal efficiency, maximum power, and tail pipe emissions. This paper provides a quantitative analysis of these effects and identifies guidelines for designing a new Atkinson cycle engine. [ABSTRACT FROM AUTHOR]

To address the growing scarcity and rising costs of fossil fuels, researchers are exploring alternative energy sources that can mimic the conventional fuels. This study focused on ternary fuel blends made from waste fried oil (WFO) biodiesel, methanol, and diesel. To enhance their stability, 10, 20, and 30 ml of n-butanol per litre of ternary blends are added. The blends were tested in a variable compression ratio (VCR) engine under peak load conditions. The experiments are carried out by varying the compression ratio (CR) of the engine from 16:1 to 18:1. The results showed that increasing the CR improved combustion for all fuel blends. Among the ternary blends, B30M20D50 outperformed pure diesel in terms of combustion characteristics. When compared to diesel, B30M20D50 yielded 5.08 %, 5.31 %, and 4.59 % higher Pmax at CR 16:1, 17:1, and 18:1, respectively. Under the same conditions, NHRR outperformed diesel by 1.46 %, 3.12 %, and 2.44 %, respectively. While ternary blends with up to 20 % methanol exhibited stable combustion, higher methanol concentrations led to erratic rise in the coefficient of variation. The interdependency analysis revealed a strong correlation between the combustion parameters for the B20M30D50 blend across different compression ratios.

In diesel engines, soot deposition on lubricating oil causes a decline in lubrication performance, but the mechanism is not well understood. The purpose of this study is to construct an equation for predicting the amount of soot contamination in lubricating oil. The effects of the temperature difference between the spray flame and the wall surface on the amount of soot deposition were investigated for measuring the soot concentration by the LII method, the flame temperature by the two-color method, and the amount of soot adhesion by the transmitted light attenuation method. [ABSTRACT FROM AUTHOR]

Modeling of in-cylinder combustion in internal combustion engines is still a complex issue. Further development studies are needed to accurately predict the performance, combustion regimes, and emission behavior of fuels other than conventional fuels such as gasoline or diesel. In this study, experimental data in full load diesel combustion regime were used to validate the numerical model using the 0/1-dimensional AVL Boost program. Vibe 2-Zone combustion model was used during the validation studies. As a result of the analysis, when the performance and emission values were examined, it was seen that there was close to 94% compliance. After numerical verification in the diesel combustion regime, the system was converted to a reactivity controlled compression ignition (RCCI) engine with the addition of an injector for propane injection to the intake port. Afterwards, the effects of the use of different propane ratios and different start of combustion times on the performance, combustion characteristics, and emission values of an RCCI engine were investigated by keeping the total fuel mass constant. As a result, with the use of 90% propane and 10% diesel fuel, an 11% improvement in performance was achieved, and it was observed that the use of catalytic exhaust equipment was not required for emission values. In addition, it has been determined that the best combustion start time for performance and emission values was -6 °CA ATDC. [ABSTRACT FROM AUTHOR]

The thermal barrier coating method is applied using materials with low thermal conductivity to increase the efficiency and improve the emissions of internal combustion engines. However, coated surfaces may be damaged due to the high thermal and pressure stresses encountered by the piston surface in the combustion chamber during engine operation. In this study, experiments and analysis were carried out for four piston models to analyze the coating layer and increase its strength: two partially coated piston surface models, a fully coated model, and an uncoated piston model. The results of the transient thermal analysis revealed that the fully coated piston model exhibited the highest surface temperature. Additionally, heat losses were observed to be lower in the fully coated model compared to the other piston models. Partially coated piston models exhibited lower heat flux on the coated surface but higher heat flux on the uncoated combustion chamber surfaces. Combustion analysis indicated that the fully coated piston model exhibited the highest in-cylinder temperature and pressure values, while the uncoated model had the lowest values. When comparing heat transfer rates on the walls, the uncoated piston model exhibited the highest transfer, whereas the fully coated piston model exhibited the lowest. Finally, the fully coated piston demonstrated the highest combustion efficiency.

The complex phenomena of pre-chamber jet combustion and their mechanisms were discussed using the CFD Converge. The second half of the combustion period (MFB50-90) was more dominant for knocking than MFB10-50 due to the higher in-cylinder temperature. Pre-chamber jet combustion shortened MFB50-90 by forming a complex flame front due to jet penetration rather than strong turbulence caused by jet streams. The larger the pre-chamber volume, the faster the combustion in the pre-chamber, and the higher the pressure ratio between the main and pre-chamber. Even if the jet intensity was increased, there was a limit to the complexity of the flame front. [ABSTRACT FROM AUTHOR]

The application of a char derived from fruit peel waste and other municipal wastes as solid fuel depends on its physico-chemical properties. In this work, fruit peel waste (FW) along their mixture with facial tissue waste (FT) and wrapping paper waste (WP) as well as their respective hydrochars (FWHC, FTHC, and WPHC) produced via hydrothermal carbonization (HTC) was characterized in detail to ascertain their applicability as solid fuel. Moreover, the elemental O contents for FTHC and WPHC were about 12.8 and 5.1% respectively higher than FWHC. Heating value analysis indicated that WPHC had the highest HHV of 5164 kcal/kg. Combustion kinetic studies, carried out by thermogravimetric technique, revealed that about 33.78 kJ/mol of energy was required to generate a combustion reaction for WP, higher than the energy required to ignite WPHC (28.2 kJ/mol). The regression coefficient (R2) values were higher than 0.94, indicating that the Arrhenius equation could be used to model the sample combustion process. Overall, the study showed that Co-HTC of FW with paper-based municipal waste such FT and WP is an effective method of converting FW to a cleaner hydrochar (HC) with high calorific value and less sulphur content. [ABSTRACT FROM AUTHOR]

In view of the strong interest in the adoption of hydrogen as an alternative fuel for internal combustion engines, the authors present the results of an experimental activity aimed at evaluating the effect of hydrogen use on performance and emissions of a heavy-duty (HD) spark ignition engine. The engine, installed on a test bench and working with compressed natural gas (CNG) in its standard version, has been fed with blends of CNG and H 2 , at various percentages (15% and 25% of H 2 by volume) and tested in steady-state and transient driving conditions. The analysis in steady state was performed in two working modes: at the same combustion barycentre and at the same nitrogen oxides (NO x) emissions of the pure CNG case, by means of proper spark advance calibrations. A detailed combustion and emissions analysis were performed, highlighting a coherent response of the engine to the replacement of CNG with H 2. The NO x increment tendency is easily counteracted by reduced SA settings, while total hydrocarbons and carbon oxides emissions reduction were measured when the blends were burnt. Consistent carbon dioxide emission mitigation was revealed, mainly in transient conditions, operated at the same ECU calibration of the pure CNG case. The main novelty of the work is in providing an in-depth study of the engine behaviour to hydrogen addition in transient condition. The response of engine management system to different fuels when rapid speed and torque variations occur, were evaluated. In this sense, the study offers detailed information on the feasibility of the use of hydro methane in existing engine architecture; such mixtures can represent, in the next future, a probable fuel option in view of the oncoming decarbonization process. Moreover, new insights on particle emission burning hydro-methane are presented. The results of engine-out PN emissions along a transient cycle revealed a correlation between particle emissions spikes with specific phases of the driving cycle and a trend in PN reduction in case of hydrogen addition. • Natural Gas/Hydrogen blends. • Heavy-Duty spark ignition engines. • Steady-state and transient engine operating modes. • Performance, combustion and emission analysis. • Particles number and size distribution characterization. [ABSTRACT FROM AUTHOR]

To realize a super-leanburn SI engine with a very-high compression ratio, it is required to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for stable combustion. Ethane shows a long ignition delay time at a low temperature close to that of methane, but a short ignition delay time at a high temperature close to that of gasoline. In the present study, the antiknocking effect of adding methane with the RON of 120, ethane with the RON of 108, or propane with the RON of 112 to a regular gasoline surrogate fuel with the RON of 90.8 has been investigated. Adding each gaseous fuel by less than 0.4 in heat fraction advances knocking limit in the descending order of SI timing advance of ethane, methane, and propane, and in the descending order of CA 50 advance of ethane, propane, and methane. Adding methane extends combustion duration slightly, but adding ethane or propane shortens it considerably. Shortening combustion duration has a negative effect on advancing knocking limit SI timing. The effect on advancing knocking limit CA 50 is dependent on not the RON's of the gaseous fuels, but the rates of OH removal by the gaseous fuels. The antiknocking effect of adding each gaseous fuel to a premium gasoline surrogate fuel with the RON of 100.2 has been also investigated. The effect on advancing knocking limit CA50 is not dependent on whether the liquid fuels have cool-flame reactions or not. [ABSTRACT FROM AUTHOR]

Improving the thermal efficiency of gasoline automobile engines is a very important issue as a measure against global warming. For that purpose, we need to optimize the gasoline fuel so that the high engine performance can be fully exhibited. In the present study, the ignition delay times of light olefins and oxygenated hydrocarbons (assuming biofuels), which can improve knock resistance and expand the lean limit, were measured using a high-pressure shock tube and these chemical effects were discussed. In addition, new gasoline surrogates containing these components appropriately were suggested and their fuel performances were also examined. [ABSTRACT FROM AUTHOR]

Toward the realization of carbon neutrality, it is expected to improve engine thermal efficiency by combining combustion and fuel, as well as reduce WTW CO2 by reducing the carbon intensity of fuel. In this study, the evaluation of the effect of fuel molecules on thermal efficiency and exhaust emissions using a highly efficient super lean burn engine of λ2 or higher is conducted, and the characteristics required for fuel is clarified. [ABSTRACT FROM AUTHOR]

We propose methods which train deep learning models (DNN, Deep Neural Net) to separate knocking sounds from engine radiation noise measured by a microphone. These DNNs contribute to the automation of ignition timing calibration for the gasoline engine by evaluating the intensity of knocking. The previous method has two problems. First, separation performance deteriorated for engines not included in the training data. Second, this method required in-cylinder pressure for training. In this paper, we propose a method that can separate the knocking sounds of engines not included in training data and an unsupervised method that does not require in-cylinder pressure. [ABSTRACT FROM AUTHOR]

Highly oxygenated fuels can effectively reduce afterburning in diesel diffusion combustion and improve the degree of constant volume heat release in spite of increases in injection duration due to smaller heating values. The mechanism of afterburning reduction and the structural differences in the diesel fuel spray with changing the oxygen content in the fuel were investigated in a constant volume vessel and analyzed with 3D CFD simulation. The result showed that the equibalance ratio inside the spray decreased with increases in the oxygen content due to lower theoretical air-fuel ratios, promoting the spray combustion after the end of injection. Further, the combustion characteristics and the exhaust gas emissions of the oxygenated fuels were investigated in an experimental single cylinder diesel engine with modern specifications. With increasing oxygen contents, the degree of constant volume heat release increased with reductions in the afterburning, resulting in higher indicated thermal efficiencies. However, the indicated thermal efficiency showed a maximum at around 27 mass% of the oxygen in fuel and further increases in the oxygen contents resulted in lower indicated thermal efficiencies due to larger cooling losses. [ABSTRACT FROM AUTHOR]

To realize a super-leanburn SI engine with a very-high compression ratio, it is required to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for stable combustion. Ethane shows a long ignition delay time at a low temperature close to that of methane, but a short ignition delay time at a high temperature close to that of gasoline, as well as having a higher laminar burning velocity than those of methane and gasoline. In the present study, the antiknocking effect of adding methane with the RON of 120 or ethane with the RON of 108 to a regular gasoline surrogate fuel with the RON of 90.8 has been investigated. Adding methane or ethane by 35 % or 25 % in heat fraction, respectively, shows the same knock limit SI timing as that of a premium gasoline surrogate fuel with the RON of 100.2. In the relationship between the heat fraction of the gaseous fuel and the advance of knock limit CA50, the effect of adding ethane is 1.9 times larger than that of adding methane. The effect of adding the gaseous fuel is dependent not on the RON of the gaseous fuel, but on the OH consuming rate of the gaseous fuel. The effect of adding methane or ethane to the premium gasoline surrogate fuel has been also investigated. The effect of adding ethane is 1.7 times larger than that of adding methane. The effect of adding the gaseous fuel is not dependent on whether the liquid fuel has cool-flame reactions or not. [ABSTRACT FROM AUTHOR]

The effects of fuel components on EGR and lean limits in multi-cylinder gasoline engines were investigated. The combustion stabilities for various fuel components varying the olefin contents and adding oxygenate components such as ethanol and ETBE were especially evaluated. The experimental results show that the fuel components have a significant impact for the EGR and lean limits. It was found that the fuel containing a large volume of olefin with ethanol could extend not only EGR and lean limit but also knock limit. We revealed the potentiality for improving thermal efficiency with adjusting fuel components. [ABSTRACT FROM AUTHOR]

LII measurement was performed to investigate the soot formation process in a region where diesel spray flames impinge onto the wall and adjacent these flames interact with each other. It was carried out using an optical accessible RCEM with a two-hole injector. Effects of injection pressure and ambient oxygen concentration was discussed．It was found that high concentrations of soot were formed in the interaction region, soot was formed in a wider range and remained for a long time when reducing the injection pressure, and soot was formed even when increasing the oxygen concentration, but it is reduced earlier. [ABSTRACT FROM AUTHOR]

In order to significantly reduce CO2 emissions from automobiles, it is essential to develop technologies for improving the thermal efficiency of internal combustion engines, such as lean combustion, and fuel technologies suitable for combustion. In this study, the effects of fuel composition on lean-burn engines were verified, and by analyzing the effects, fuel characteristics that achieve both knock suppression and lean-burn limit expansion were investigated. [ABSTRACT FROM AUTHOR]

To prevent extreme climate events, it is urgent to reduce greenhouse gas emissions, and research on alternative fuels for internal combustion engines is necessary. In this study, diesel spray and combustion characteristics were investigated when Fatty Acid Methyl Ester (FAME) was blended with Hydrotreated Vegetable Oil (HVO) in any ratio. As a result, blending HVO with FAME promoted atomization and improved evaporation, resulting in a lean mixture. Also, the shorter ignition delay suppressed premixing combustion, resulting in lower cylinder temperatures and lower NOx emissions, but increased THC and Smoke emissions. [ABSTRACT FROM AUTHOR]

Ammonia has received significant attention as a fuel due to its carbon-free molecular structure. However, burning ammonia is challenging because of its low laminar burning velocity. To promote the combustion velocity, the authors propose a constant volume combustion chamber with a sub-chamber. This study investigated the effects of the mixing time and equivalence ratio of the ammonia/oxygen/argon mixture on combustion. The mean velocity of the ejection from the sub-chamber can be calculated by evaluating the combustion pressure, mass fraction burned, and volume fraction burned. It was clarified that with the sub-chamber structure, the ejection from the sub-chamber improved the compression and turbulence of unburned gas in the main chamber and increased the mean flame velocity of ammonia combustion. The appropriate glow plug temperature could improve the ignitability of the fuel mixture, leading to increased combustion efficiency, maximum combustion pressure, and reduced combustion time. [ABSTRACT FROM AUTHOR]

Partial oxidized fuel in the residual gas is thought to affect the auto-ignition timing. However, the accurate composition of the residual gas cannot be determined by computer simulation even using detailed chemical reaction models. In order to clarify the composition of the residual gas, a comprehensive two-dimensional gas chromatograph equipped with a time-of-flight mass spectrometer was used to analyze the exhaust gas components emitted from spark-ignited engines as a model of residual gases. In this study, n-heptane, isooctane and diisobutylene were used as the model fuels. The main reaction paths for the low temperature oxidation of n-heptane, isooctane are different each other, suggesting that the low temperature oxidation of the saturated hydrocarbons depends on their chemical structure. However, the types of compounds detected as reaction products (the number of carbon atoms and oxygen atoms) differed depending on the fuel used. Notably, the several products detected in this study are not existed in the detailed chemistry model of lowtemperature oxidation. [ABSTRACT FROM AUTHOR]

The manuscript provides a concise overview of a four-stroke compression ignition engine, which is powered by blends of waste palm oil and waste sunflower oil methyl ester diesel. This engine operates in a dual-fuel mode with the utilization of inducted producer gas generated from bamboo leaves. This study presents a comprehensive summary of the performance, combustion, and emission characteristics of post-mixed fuels, investigated using a Kirloskar TAF1 diesel engine operating in dual-fuel mode. The primary research focus spun around the dual-fuel operation of diesel and post-mixed oils across various load conditions while maintaining a consistent gas flow rate. The findings of the study highlighted interesting trends. Particularly, the post-mixed oil methyl ester (PMOME 20+ BLP.gas) exhibited a 5.26% increase in brake-specific fuel consumption and a 4.66% reduction in brake thermal efficiency under heavy load conditions when compared to pure diesel operation. Notably, the post-mixed blend showcased improvements in smoke opacity, carbon monoxide, and unburnt hydrocarbon emissions, registering reductions of 11.22%, 20.44%, and 10.36%, respectively. Conversely, oxides of nitrogen witnessed a reduction of 19.17% during peak load conditions for the PMOME 20+ BLP gas blend, a noteworthy improvement in comparison to emissions of petroleum diesel. Based on these observations, the current research suggests that integrating renewable fuels into dual-fuel engines holds promise as a viable approach for both economic advancement and the essential addressing of the looming scarcity of conventional petroleum diesel. [ABSTRACT FROM AUTHOR]

The mandatory migration from fossil to renewable energy sources requires the characterization of new alternative fuels. One important step in fuel characterization is the test in optical engines, which allows the morphological characterization of flames. This analysis requires the post treatment of images by using segmentation. In many cases, an automatic threshold presents shortcomings as the flames may present different regions with variable luminosity, as also reflections from valves and cylinder liner. Consequently, a time-consuming manual image processing is required and, therefore, an automatic procedure would be welcome. The use of deep learning techniques for image segmentation is a promising alternative for such task, which has showed excellent results in several applications. In this study, two different models were trained to identify flames in images obtained from an optical engine operating at various conditions. The dataset used to train the models was generated by using images from tests with several types of fuels and combustion modes. The effects of image resolution and the generalization capabilities for different fuels and combustion operation were investigated. After analyzing the results, the use of deep learning methods to identify and characterize flames was validated as a mean for improving processing time. [ABSTRACT FROM AUTHOR]

The production of biofuel from olive mill wastewater (OMWW) may be one of the promising techniques for use in diesel engines. In this study, biofuel was produced from the hydrothermal liquefaction of OMWW using a methanol-water co-solvent. Biofuel blends of 10% (B10), 20% (B20) and 30% (B30) by volume of biofuel, were prepared. The chemical and physical properties of biofuel blends are mostly similar to those of conventional diesel fuel. The engine speed was kept constant (1500 rpm) throughout the tests under different engine loads (25, 50, 75 and 100%). The effects of biofuel-diesel blends on exhaust emissions and engine performance were investigated. The results show that the in-cylinder pressure follows almost the same trend for all fuels. However, at high loads, with increasing biofuel blend, the combustion duration tends to become longer. The B10 blend provided close results to diesel fuel in terms of performance and polluting emissions. Moreover, the use of B10 resulted in reduced emission levels, with 11% of unburned hydrocarbons, 12% of particles and 26% of carbon dioxide compared to the other blends. [ABSTRACT FROM AUTHOR]

Increasing concerns caused by environmental pollution have promoted the use of cleaner and renewable fuels in internal combustion engines. Biodiesel is used as an alternative fuel in diesel engines in many countries. However, compared to diesel fuel, the high viscosity of the biodiesel and consequently the poorer atomization characteristic causes its use to be limited. In order to improve these properties of biodiesel, researches have been conducted on the use of various additives. In this study, the effects of carbon nanotube additive on performance and emission characteristics of a single cylinder direct injection diesel engine powered by biodiesel-diesel fuel were investigated. In experiments carried out at full load depending on engine speed, thermal efficiency, engine power and torque and exhaust emissions were examined. The in-cylinder pressure and heat release rate were also analysed at the maximum torque speed. It was determined that the carbon nanotube additive advanced the start of combustion and improved thermal efficiency. Maximum thermal efficiency was achieved as 39.3% when 100 ppm carbon nanotube additive was used. It was also found that the carbon nanotube additive reduced CO, HC and soot emissions, but increased NOx emissions due to improved engine performance. It was determined that 100 ppm carbon nanotube additive increased NOx emissions by approximately 11%, whereas CO, HC and soot emissions decreased by 20%, 26% and 7.9%. [ABSTRACT FROM AUTHOR]

Due to increasingly stringent fuel consumption and emission regulation, improving thermal efficiency and reducing particulate matter emissions are two main issues for next generation gasoline engine. Lean burn mode could greatly reduce pumping loss and decrease the fuel consumption of gasoline engines, although the burning rate is decreased by higher diluted intake air. In this study, dual injection stratified combustion mode is used to accelerate the burning rate of lean burn by increasing the fuel concentration near the spark plug. The effects of engine control parameters such as the excess air coefficient (Lambda), direct injection (DI) ratio, spark interval with DI, and DI timing on combustion, fuel consumption, gaseous emissions, and particulate emissions of a dual injection gasoline engine are studied. It is shown that the lean burn limit can be extended to Lambda = 1.8 with a low compression ratio of 10, while the fuel consumption can be obviously improved at Lambda = 1.4. There exists a spark window for dual injection stratified lean burn mode, in which the spark timing has a weak effect on combustion. With optimization of the control parameters, the brake specific fuel consumption (BSFC) decreases 9.05% more than that of original stoichiometric combustion with DI as 2 bar brake mean effective pressure (BMEP) at a 2000 r/min engine speed. The NOx emissions before three-way catalyst (TWC) are 71.31% lower than that of the original engine while the particle number (PN) is 81.45% lower than the original engine. The dual injection stratified lean burn has a wide range of applications which can effectively reduce fuel consumption and particulate emissions. The BSFC reduction rate is higher than 5% and the PN reduction rate is more than 50% with the speed lower than 2400 r/min and the load lower than 5 bar. [ABSTRACT FROM AUTHOR]

To correspond with CO2 reduction from the automobile, in conjunction with electrification, improving the thermal efficiency of ICE is crucial and lean and EGR diluted combustion are being studied. It is important to enhance combustion in lean and EGR diluted condition and it is known that the effects of fuel components are significant. In this study the effects of fuel components on the lean & EGR diluted combustion are examined with L4 engine and the fuel specifications required to enhance lean combustion are reported. [ABSTRACT FROM AUTHOR]

In recent years, disposal of used cooking oil has drawn everyone attention due to its detrimental and hazardous effects upon health and environment. However, used cooking oil has great potential to be a fuel supplement after its appropriate processing for biofuel formulation, globally. Attributed to the various advantages of microemulsion-based hybrid biofuel (MHBF) technique, the present experimental investigation has focused to investigate the effects of used cooking oil (UCO)-based hybrid microemulsion biofuel (UCOMHBF), added with 2-ethylhexyl nitrate (2-EHN) (cetane enhancer) upon performance, combustion and emission characteristics of a 4-stroke single-cylinder CI engine. 2-EHN was added in UCOMHBF (UCO (55%) (vol.%), anhydrous ethanol (E) (28%) (vol.%) and 2-butanol (B) (17%)) in proportion of 500 (UCOMHBF500), 1000 (UCOMHBF1000) and 1500 (UCOMHBF1500) ppm, respectively. The brake-specific fuel consumption (BSFC) of CI engine test rig for UCOMHBF1000 was found 8% lower than UCOMHBF and B100 and 2.5% higher for UCOMHBF1500, respectively. Combustion delay was observed with MHBFs w.r.t petrodiesel, but improved combustion was observed with up to 1000 ppm addition of 2-EHN in UCOMHBF at full load condition. Addition of 1500 ppm 2-EHN in UCOMHBF showed uncontrolled flame propagation at the end of the compression stroke which resulted in incomplete combustion during power stroke. 2-EHN addition in UCOMHBF has also lowered the mean of nitrogen (NOx) in the range of 2.06–33.33% w.r.t petrodiesel. Hence, it can be concluded that UCOMHBF1000 has shown the superior characteristics from all other UCOMHBFs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Passive pre-chamber can enhance the stability of lean combustion in TJI hydrogen engines. • Passive pre-chamber internal flow characteristics, combustion, and energy conversion analysis. • Analysis of combustion and emission for TJI hydrogen engines at different injection strategies. • With the delay of SOI, the power output of the TJI hydrogen engine gradually improves. • The split-injection strategy will increase the power performance and combustion instability. Turbulent jet ignition (TJI) effectively achieves lean and stable combustion in hydrogen engines. However, research on injection strategies for TJI hydrogen engines is still lacking. In this study, experimental methods investigated the effects of single and split injection strategies on the combustion and emissions of TJI hydrogen engines under medium loads. The numerical simulation reveals the operational characteristics of fuel distribution, ignition capability, and energy conversion in the pre-chamber at different injection times in a single injection strategy. This work is conducted at 1600 rpm with a manifold absolute pressure of 70 kPa. The experimental results indicate that the delay of the start of injection (SOI) can enhance the performance of the TJI hydrogen engine. However, as SOI approaches TDC, emissions worsen, and combustion stability decreases. When SOI is 90°CA BTDC, the brake mean effective pressure (BMEP) and brake thermal efficiency (BTE) can achieve 3.1 bar and 32.9 %, with the coefficient of variation of the IMEP (COV IMEP) of 1.6 % and lower emissions. For the split injection strategy, delaying the secondary end of injection (SEOI) can increase BMEP and BTE. As SEOI gradually delays the TDC, emissions deteriorate sharply. Under the split injection strategy, COV IMEP is higher, which is unfavorable for hydrogen engine applications. [ABSTRACT FROM AUTHOR]

This study aims to analyse the detailed combustion characteristics of tire derived fuel blends (TDF) in small-size DI diesel engines. From this point of view, the refined TDF and reference diesel fuel (No.2 Diesel) were blended in various percentages and tested in a single cylinder naturally aspirated DI diesel engine to clarify its detailed combustion characteristics. The experimental test results point out that ignition delay period is observed to be 4.32 CAD (No.2 Diesel fuel), 5.57 CAD (TDF20), 6.56 CAD (TDF40), 8.48 CAD (TDF60), 11.09 CAD (TDF80), and 14.26 CAD (TDF100) for the low engine speeds (1400 rpm). With the increasing TDF in fuel blends and engine speed, the ignition delay period prolongs more, and the total combustion duration shortens. However, due to the excessively long ignition delay period of TDF100, it is not possible to run the test engine at more than 3000 rpm. TDF blends usually demonstrate a longer premixed combustion period than that of No.2 Diesel, while it exhibits a shorter diffusive combustion period. TDF blends also display a higher maximum value of heat release rate (HRRmax), a higher peak value of in-cylinder pressure (Pmax) and a higher rate of pressure rise (dP/dCAD). In addition, combustion events occur late, and the center of combustion moves away from the top dead center into expansion stroke in the case of TDF blends. [ABSTRACT FROM AUTHOR]

In comparison with port fuel injection (PFI) engines, gasoline direct injection (GDI) engines have higher fuel efficiency. However, there are more particulate matters (PMs) including soot in the exhaust gas. Then, we need gasoline particulate filters (GPFs) with high filtration efficiency for the future stringent PM emission regulations. In this study, we simulated the filtration process on the pore-scale of the filter wall by a lattice Boltzmann method (LBM). The structure of filter wall was obtained by an X-ray CT technique. We discussed pressure drop and initial filtration efficiency, which are important characteristics of GPFs, by changing the inlet velocity of exhaust gas and soot particle size. Results show that, as the soot particle size is smaller, the thicker soot cake layer is formed on the surface of the filter wall, resulting in the smaller pressure drop. The initial filtration efficiency is higher as the particle size is smaller due to the Brownian diffusion. Moreover, when the particle size is larger, the interceptional effect is dominant, and the initial filtration efficiency is higher. As the inlet velocity is smaller, the thicker soot cake is formed on the surface of the filter wall due to the higher filtration efficiency. The pressure drop decreases as the inlet velocity is smaller. [ABSTRACT FROM AUTHOR]