Engine Speed Research Articles

Влияние острой токсичности бисфенола А на поведение и локомоторную активность Danio rerio

The results of evaluating the effects of acute exposure of Danio rerio to bisphenol A solutions on behavioral traits and locomotor activity using the open field test are presented. It was found that bisphenol A in the exposure aquariums resulted in impaired movement, hyperactivity, increased mucus secretion, and increased gill cover movements. Fish not exposed to the pollutant in the open field test spent most of their time near the edges of the aquarium, exhibiting moderate exploratory activity. Bisphenol A in the open field test at concentrations greater than 1 mg/l caused a significant increase in mean locomotor speed (to 11.1 cm/s) and a decrease in inactivity time (to 9.9 s). The indices of locomotor activity in Danio rerio, significantly altered by bisphenol A, showed a clear concentration-effect relationship: for inactivity time in the inner circle, R² = 0.6765, and in the outer ring, R² = 0.7140; for movement speed in the inner circle, R² = 0.4365, and in the outer ring, R² = 0.4011. Acute toxicity of bisphenol A resulted in the development of anxiety-like behavior in fish, characterized by hyperactivity, increased exploratory activity, and decreased thigmotaxis.

Optimization of Noise Emission Level in Diesel Engine with Biodiesel Application Using Response Surface Methodology

This study used biodiesel to run a single-cylinder direct-injection diesel engine. The palm oil methyl ester is blended in different ratios of up to 20% and tested with different engine speeds and loads for noise level measurement. Mathematical modeling was then developed to correlate responses obtained by the noise levels of the engine components to the factors, including engine speed, engine load, and biodiesel blending percentage. Finally, using the developed models, all the numeric factors were optimized. Modeling results indicated that the significance of factors could vary for the engine components, whereas in this study, the intake phase-related factors showed the significance of all factors. Meanwhile, the optimization results highlighted that the best solution with the highest desirability number to satisfy all the responses was the B20 fuel blend (20% biodiesel fuel and 80% diesel fuel blend by volume) with 1200 rpm of engine speed. In conclusion, the study's outcomes revealed that optimization should be considered in developing a new policy for using biofuel in internal combustion engines.

Comparative analysis of combustion and emission characteristics in RCCI engines using alcohol fuels with different carbon numbers.

Alcohol fuels with different carbon numbers such as propanol (C3), butanol (C4) and pentanol (C5) have lately become popular in both conventionally and RCCI-operated diesel engines thanks totheir high cetane number (CN) and oxygen content along with lower latent heat of evaporation, which are useful for reducing the high CO/HC emissions, whereas RCCI mode still suffers from these emissions. Therefore, in this study, these three alcohol fuels with carbon numbers ranging from C3 to C5 were employed as low-reactivity fuel (LRF) in a single-cylinder RCCI engine under a constant engine speed of 2400rpm and varying loadings (from 20 to 60% of full load at 20% intervals) and premixed ratios (from 0 to 60% with 15% intervals) when using B7 as high-reactivity fuel (HRF). In the experimental study, the effect of oxygen content, latent heat of evaporation, and cetane number which changes linearly with the carbon number of alcohols used, on exhaust emissions, were analyzed. When compared to conventional diesel mode (CDM), RCCI mode using alcohol fuels increased HC and CO emissions but decreased smoke opacity at a great level. The greatest reduction in both CO emissions and smoke opacity was recorded with the use of propanol which has the highest oxygen content, while pentanol with the lowest latent heat of evaporation had success in reducing HC emissions. In addition, NOx emissions were reduced by up to 60% when butanol was used as low-reactivity fuel. Ignition delay increased more during RCCI operation with propanol having an octane number of 118, whereas butanol and pentanol have 92 and 78, respectively. It was concluded that the properties of alcohol fuels such as the oxygen content and latent heat of evaporation had a significant effect on HC/CO emissions in RCCI engines.

Analyzing the impact of injection timing variations on the performance of multi-cylinder CNG direct injection spark-ignition engine

Abstract Objective: This study investigates the impact of Compressed Natural Gas (CNG) injection timing on the performance of a retrofitted CNG Direct Injection (CNG-DI) engine. The aim is to understand how varying injection timing affects key performance metrics such as torque, power, thermal efficiency, and fuel consumption in CNG-DI engines, providing insights for system optimization.
Methods: A 1298 cc, four-cylinder, four-stroke spark ignition engine with a compression ratio of 9 was retrofitted for CNG-DI operation. Modifications included a redesigned cylinder head for high-pressure injectors, controlled by a programmable gas ECU. The engine was tested with three injection timings: Early Injection (EI) at 230° BTDC, Optimal Injection (OI) at 180° BTDC, and Late Injection (LI) at 130° BTDC. Performance, Emission and Combustion parameters were evaluated across engine speeds from 1000 to 3100 rpm.
Results: Late Injection (LI) timing improved torque, power, BMEP, thermal efficiency, and volumetric efficiency by 4-16% within the 1000-2200 rpm range, attributed to better combustion dynamics. Optimal Injection (OI) timing achieved 4-12% higher performance in the 2500-2800 rpm range due to improved mixture formation. Early Injection (EI) timing resulted in 3-8% improvements at speeds above 2800 rpm, driven by faster combustion and increased peak power.
Conclusion: This study highlights the crucial role of injection timing in optimizing CNG-DI engine performance: Late Injection improves fuel efficiency at lower speeds, Optimal Injection enhances thermal efficiency at mid-range RPMs, and Early Injection maximizes power at higher RPMs. However, the study is limited by its focus on a single engine configuration and does not consider emissions or Life Cycle Assessment (LCA). Future research should investigate the environmental impact of injection timing through LCA and assess the long-term durability of engine performance.

Improvement of Engine Combustion and Emission Characteristics by Fuel Property Modulation

The sustainability of diesel engines has come to the forefront of research with the growing global interest in reducing greenhouse gas emissions and improving energy efficiency. The aim of this paper is to support the goal of sustainable development by improving the volatile properties of diesel fuel to promote cleaner combustion in engines. In order to study the effect of diesel fuel volatility on spraying, combustion, and emission, the tests were carried out with the help of the constant volume chamber (CVC) test rig and an engine test rig, respectively. CVC test: A high-speed video camera recorded the spray characteristics of different volatile fuels in a constant-volume combustion bomb. The effects of different rail pressures and ambient back pressures on the spray characteristics were investigated. Engine test: The combustion and emission characteristics of different volatile diesel fuels under different load conditions (25%, 50%, 75%) were investigated in a four-stroke direct-injection diesel engine with the engine speed fixed at 2000 rpm. The test results show that as the rail pressure increases and the ambient pressure decreases, the spray characteristics of the fuels tend to increase; for the more volatile fuels, although reducing the spray tip penetration, the spray projected area and spray cone angle increase, which is conducive to improving the homogeneity of the fuel and air mixing in the cylinder. The improvement of fuel volatility can form more and better-quality mixtures within the ignition delay time (ID), resulting in a 1–2% increase in peak cylinder pressure and a 2–4% increase in peak heat release. For different loads, pre-injection heat release is generated to redefine the ID and combustion duration (CD). Improved fuel volatility effectively reduces carbon monoxide (CO) emissions by about 8–10% and hydrocarbon (HC) emissions by about 13–16%, but it increases nitrogen oxide (NOx) emissions by about 8–11%. Analyzing from the perspective of particulate matter (PM), combined with the aromatic content of volatile fuels, it is recommended to use fuels with moderate volatility and aromatic content under low load conditions, and at medium to large loads, the volatility of the fuel has less weight on particulates and more weight on aromatics, so it is desirable to use the fuel with the lowest volatility and lowest aromatic content of the fuel selected.

Impact Of Various Biodiesel And Partially Hydrogenated Biodiesel Mixtures On Torque, Power, And Specific Fuel Consumption: An Experimental Study With Mathematical Modeling

The widespread reliance on diesel fuel for transportation and industrial applications is causing environmental pollution, showing the need to explore better alternatives. In this context, the use of biodiesel, or in combination with partially hydrogenated biodiesel, presents a potential substitute for conventional diesel fuel. Therefore, this research aimed to investigate the effects of incorporating biodiesel or partially hydrogenated biodiesel into diesel fuel on torque, power, and Specific Fuel Consumption (SFC). The experiments were carried out by incorporating seven mixtures of diesel fuel, varying from 100% to 70%. The results showed that both biodiesel and partially hydrogenated biodiesel improved power, torque, and SFC compared to conventional diesel fuel, across various ratios and engine rotation. The optimal performance of these mixtures was achieved at approximately 2000 rpm (rotation per minute). Additionally, mathematical models were developed to predict torque and power. The models were optimized for use at engine speeds of 2000 rpm and 4000 rpm, with biodiesel concentrations ranging from 10% to 30% in fuel mixture.

Impact of Influence of Piston Design Parameters on the Hydrodynamic Characteristics of Internal Combustion Engines—A Numerical Study

Piston top rings in the combustion engine play a crucial role in the overall hydrodynamic performance of engines, such as power loss, minimum film thickness and friction forces, by ensuring sealing and minimizing the leakage of burnt gases. This present paper examines the influence of four key parameters of the top ring, such as ring width, ring temperature, ring tension, and ring surface roughness on the hydrodynamic behavior at the ring/cylinder contact. These parameters play a significant role in the formation and maintenance of the oil film, directly influencing hydrodynamic indicators such as the minimum oil film thickness, friction force, power loss, oil pressure, and the ring angle twist. This article relies on hydrodynamic models and numerical simulations performed using GT-SUITE version 6 software to analyze these effects. The pressure curve used in this simulation is experimentally validated for an engine speed of 2000 RPM. It was found that an increase in the top ring temperature reduces the oil’s viscosity, decreasing the film thickness and increasing the risk of metal-to-metal contact. Increasing the roughness of the ring enhances oil film stability, especially at the bottom dead center (BDC) points during each phase of the operating cycle. Further, three different types of ring profiles were investigated for friction forces by varying the speed of the engine.

Strategic optimization of engine performance and emissions with bio-hydrogenated diesel and biodiesel: A RVEA-GRNNs framework

This study investigates the effects of blending bio-hydrogenated diesel and biodiesel on engine performance and emissions across various engine speeds (2000-3000 rpm) and loads (25-90%), addressing the growing demand for sustainable transportation fuels. Using a single-cylinder diesel engine from POLAWAT ENGINE Company Limited, we evaluated different bio-hydrogenated diesel and biodiesel blends, optimizing their composition through the Reference Vector Guided Evolutionary Algorithm with a surrogate objective function via Generalized Regression Neural Networks. Results indicate that engine performance is closely linked to combustion temperature, which significantly affects fuel consumption and thermal efficiency. Bio-hydrogenated diesel demonstrated superior performance compared to conventional diesel, with lower fuel consumption and higher thermal efficiency, attributed to its higher cetane index (78 vs. 56) and heating value (47.02 MJ/kg vs. 43.48 MJ/kg). However, increasing biodiesel content in blends tended to increase fuel consumption and decrease efficiency due to biodiesel's lower heating value (39.62 MJ/kg) and higher viscosity (5.16 cSt vs. 2.58 cSt for bio-hydrogenated diesel). Emission analysis revealed that bio-hydrogenated diesel generally produced lower hydrocarbon, carbon monoxide, and smoke emissions than conventional diesel, though nitrogen oxide emissions were slightly higher. Biodiesel blends often showed increased emissions, particularly at higher blend ratios, due to poor fuel atomization. The Generalized Regression Neural Networks model demonstrated high accuracy in predicting engine performance and emissions, with coefficient of determination (R2) values exceeding 0.98 and mean absolute percentage errors below 5%. Optimization results indicated that bio-hydrogenated diesel ratios centered around 90% provided the best balance of performance and emissions. This research bridges critical gaps in combined bio-hydrogenated diesel and biodiesel usage and artificial intelligence-driven biofuel optimization, providing valuable insights for practical implementation in Thailand's agricultural sector.

Assessment of trade-off, exergetic performance, and greenhouse gas impact-cost analysis of a diesel engine running with different proportions of TiO2, Ag2O, and CeO2 nanoadditives

In this study, the effects of adding different proportions of TiO2, Ag2O, and CeO2 nanoparticles to a three-cylinder, water-cooled, four-stroke, direct injection diesel engine on engine performance and exhaust emissions are experimentally investigated. The experiments are conducted at four different engine loads (10, 20, 30, and 40 Nm) and a constant engine speed (1800 rpm). TiO2, Ag2O, and CeO2 nanoparticles are added to the diesel fuel at concentrations of 50 and 75 ppm each. The test fuels used in the study are as follows: D100, DTi50, DTi75, DAg50, DAg75, DCe50 and DCe75. Using the experimental results, analyses of energy, exergy, sustainability, greenhouse gas (GHG) emission impact, and cost are performed. The experimental results reveal that the use of nanoparticles in diesel fuel reduces BSFC. The highest reduction in BSFC is achieved with DTi75 fuel, averaging 9%. Additionally, DTi75 fuel shows an average increase of 19% in NOx emissions compared to D100 fuel, while smoke emissions decrease by an average of 30%. The highest average increase in exergy efficiency compared to D100 fuel is obtained with DAg50 fuel (5.6%), followed by DTi75 fuel (5.3%). The addition of nanoparticles to diesel fuel also leads to an increase in GHG emissions. Compared to D100 fuel, the highest average contribution to GHG emissions increase is shown by DTi75 fuel (12%), while the lowest average contribution is observed with DAg50 fuel (4%).

Exploring Eco-Friendly Paths: A Comparative Study of Emissions in Medium Speed Diesel Engines Utilizing Alternative Fuels through Simulation Analysis

In the ship industry, emissions from marine activities have been shown to influence air quality and climate, with pollutants such as sulphur dioxide (SO2), nitrogen oxides (NOₓ), and Carbon Dioxide (CO2). the International Maritime Organization (IMO) has implemented MARPOL Annex VI to reduce emissions from maritime activities, one of which is using alternative fuels. With the need of sustainable energy source of reducing emissions, the evaluation of alternative fuels becomes crucial. This study presents a comparative analysis of performance and environmental emissions from medium speed diesel engines utilizing different fuels, namely Biodiesel (B10-100), Heavy Fuel Oil (HFO), and Ultra Low Sulphur Fuel Oil (ULSFO) under various engine speed. the research was carried out using the Diesel-RK application with Internal Combustion Engine simulation that integrates thermodynamics and emission prediction algorithms to accurately represent the combustion process and subsequent pollutant formation. Parameters such as engine load, injection timing, and fuel properties are systematically varied to assess their impact on emissions of nitrogen oxides (NOₓ), sulfur dioxides (SO2), and carbon dioxide (CO2). Results indicate distinct performance and emission profiles for each fuel type in various engine speed. All Biodiesel and ULSFO demonstrates increasing NOₓ emissions compared to HFO with an average of 51.4%. However, they exhibit lower CO2 and SO2 compared to HFO with average of 3% for CO2 and 98.8% for SO2, this is due to higher oxygen content that can promote more efficient combustion, and both Biodiesel and ULSFO contains lower sulphur content.

Energy and exergy analysis of a SI engine fueled with anisole and isobutyl acetate with super-premium gasoline

The rising demand for fossil fuels is rapidly depleting the limited sources of crude oil, leading to harmful emissions upon combustion. Consequently, developing sustainable and environment-friendly alternatives to fossil fuels has become imperative to reduce dependence on them and decrease harmful emissions. In this study, the performance of different blends prepared by mixing biofuels with super-premium gasoline (SPG) in a spark-ignition (SI) engine at different speeds is investigated through energy and exergy analysis. Three biofuels, namely ethanol, anisole, and isobutyl acetate, are considered, and these biofuels are blended with the base SPG in volumes ranging from 10% to 30%. Letters G, E, A, and IBA are used to denote SPG, ethanol, anisole, and isobutyl acetate, respectively. Experiments were conducted on a three-cylinder, four-stroke SI engine with varying speeds. The results of different anisole-SPG and isobutyl acetate-SPG blends are compared with SPG and ethanol-SPG blends. The results of the energy and exergy analysis reveal that the maximum brake thermal efficiency (BTE) and exergy efficiency are achieved when the engine runs at 2500 rpm for SPG and different blends. Furthermore, the engine emissions of carbon monoxide (CO) are found to be lowest at this engine speed. It is also investigated that the maximum BTE and exergy efficiency are obtained for AG10 and IBAG10 blends. The maximum BTE of AG10 and IBAG10 are 31.23% and 30.82%, respectively, while the maximum exergy efficiency of AG10 and IBAG10 are 24.37% and 23.82%. At 2500 rpm, the blends AG10 and IBAG10 showed a slight reduction in BTE by 1.72% and 3.02%, respectively, compared to SPG. At the same time, the exergy efficiency of the AG10 and IBAG10 blends is reduced by 1.5% and 3.72%, respectively. On the other hand, the IBAG30 blend showed 7% lower emissions of CO and NOx compared to SPG. Among all the blends, EG30 showed the lowest reduction of HC emissions by 14% compared to SPG. Additionally, the sustainability index values decreased by 0.47% and 1.19% for AG10 and IBAG10, respectively, compared to SPG at 2500 rpm.

Polystyrene Nanomicroplastics Aggravate Ammonia-Induced Neurotoxic Effects in Zebrafish Embryos

The highly hazardous chemical ammonia has been proven to be absorbed by nanoparticles, thereby exerting highly toxic effects on aquatic organisms. As a ubiquitous pollutant in aquatic environments, polystyrene nanomicroplastics (PSNPs) have shown strong adsorption capacity due to their large surface area. Therefore, the potential joint effects of ammonia and PSNPs need to be clarified. In this study, zebrafish embryos were exposed to a water solution with ammonia concentrations (0, 0.1, 1, and 10 mg/L) with or without PSNP (100 μg/L) treatment up to 120 hpf. The results showed that combined exposure increased the accumulation of ammonia and obviously reduced the locomotor speed of zebrafish larvae compared with exposure to ammonia alone. Further studies indicated that PSNPs can aggravate ammonia-induced neurotoxicity by altering the cholinergic system, dopaminergic neurons, and the retinal structure in zebrafish larvae. In addition, our results revealed that ammonia caused significant alterations in the expression of genes related to neurodevelopment and retinal development, and PSNPs exacerbated this adverse effect. In conclusion, PSNPs can aggravate ammonia-induced neurotoxicity in the early stage of zebrafish and their associated health risk to aquatic animals should not be underestimated. The main contribution of this article lies in revealing the synergistic neurotoxicity of ammonia and PSNPs in the early stage of zebrafish. Moreover; it emphasizes that the associated health risks to aquatic animals should not be underestimated.

A comprehensive analysis of a dual fuel engine operating on cottonseed oil methyl ester and hydrogen

This study investigates the effects of hydrogen addition on a compression-ignition (CI) engine that operates on cottonseed oil methyl ester (CSOME). Hydrogen was introduced into the engine inlet manifold at flow rates ranging from 5 Liters per minute (LPM) to 20 LPM, with intervals of 5 LPM (designated as C100H5, C100H10, C100H15, and C100H20). The engine was operated on 100 % Cottonseed Oil Methyl Ester (C100) at various load conditions in a constant speed engine. It was observed that under all load situations, the temperature of the exhaust gas increased as the hydrogen flow rate increased. Maximum of 16.66 % increment in exhaust gas temperature was noted with C100H20 than neat diesel operation. Similarly, as hydrogen induction rates increased, the cut-off ratio, effective compression ratio, and volumetric efficiency all dropped. On the other hand, both brake thermal efficiency and second law efficiency were increased by 16.11 and 13.41 % than neat diesel while operating with C100H20 at 100 % load condition. The peak values for in-cylinder pressure and heat release rate were found to be 4.18 %, and 21.85 % higher than neat diesel for C100H20 with maximum load applied. Nitrogen monoxide emissions increased as a result of the increase in hydrogen induction flow rate by maximum of 40.51 % and then diesel. However, emissions of oxides of carbon (CO and CO2), hydrocarbons, and soot decreased significantly with the introduction of hydrogen. The results indicate that use of hydrogen in CI engine along with cotton seed oil shows positive sign in terms of performance and emission with trends in NO emission which can further be reduced by adopting EGR or After gas treatment.

Simulation of Ground Power Unit-3 Stirling Engine With Air as Working Fluid

Abstract The immediate need to mitigate climate change presents a chance to move civilization in the direction of a more sustainable future. A Stirling engine has multifuel capabilities such as biomass, solar thermal, and waste heat and hence can contribute significantly to the energy mix of fuel sources. The most common working fluids for Stirling engines are hydrogen, helium, and air, with air being the least expensive and safest. Studies analyzing Stirling engine performance with 3D CFD are limited, and even fewer use air as the working fluid. This research presents a novel 3D CFD analysis of the Ground Power Unit-3 (GPU-3) Stirling engine with air as the working fluid using ansys fluent. The fluid domain was modeled in SolidWorks and one-eighth of the geometry was used for simulation with realizable enhanced wall treatment (EWT) k–ε as an eddy viscosity model. On average, there was a reduction in power output by 50% when air was used as working fluid against helium as working fluid. Engine's power output decreases as the engine's speed increases. The impinging effect contributes to vortex formation and temperature variation within the engine components was nonsinusoidal, this is in line with similar studies performed on GPU-3 Stirling engine.

Investigation of the Influence of Lubricating Oil Viscosity on the Wear-Reducing Characteristics of Cylinder Liner Surface Texture

Lubricating oil and cylinder liner surface textures can significantly reduce the friction coefficient between the piston ring and the cylinder liner, thereby improving engine performance. However, the friction-diminishing mechanisms between the lubricating oil and surface texture remain unclear. Properly combining lubricating oil and surface texture can achieve better friction reduction effects. This paper, based on a transient thermo-hydrodynamic model developed in MATLAB 2020a, conducted numerous simulation experiments to explore the matching characteristics of textured cylinder liners. The study provides theoretical support for the future selection of lubricating oils for textured cylinder liners. The results show that, within the range of the circular texture parameters used in this study, the texture radius is directly proportional to the reduction in friction mean effective pressure (FMEP), while the texture depth is inversely proportional to the FMEP reduction. At the same rotational speed, as the viscosity of the lubricating oil increases, the friction-reducing effect of the texture on the piston ring–cylinder liner pair decreases. When the texture depth is 2 μm, the engine speed is inversely proportional to the reduction in FMEP. As the texture depth increases from 2 μm to 6 μm, there is a significant change in the friction-reducing effect: for the 2 μm texture, the friction-reducing impact decreases with increasing lubricant viscosity, while for the 6 μm texture, the friction-reducing effect increases with increasing lubricant viscosity.

DC microgrid for EV charging station with EV control by using STSM controllers

Abstract This study explores innovative control strategies for electric vehicle (EV) charging stations in a DC Microgrid powered by solar and wind energy. A new methodology regulates the dc-link voltage through various converters while a modified vector control method enhances the performance of switched reluctance motors (SRMs). The implementation of super twisting sliding mode (STSM) controllers show superior performance compared to traditional PI and Fuzzy controllers. The design of an asymmetrical converter with four battery banks also minimizes charging durations. The real-time test system (RTS) effectively managed power generation within a DC microgrid, demonstrating a stable voltage at the DC bus despite variations in total generation from photovoltaic (PVS) and wind systems. In Case 1, the controller successfully maintained power balance while charging electric vehicles and managing DC loads. During load torque adjustments, the system maintained a steady motor speed of 320 RPM even with a load torque increase from 5 Nm to 50 Nm at 3 s, showcasing its robust vector control strategy. Notably, the system facilitated a reverse operation at 10 km h−1 (80 RPM) by seamlessly adjusting the engine’s reference speed from 80 RPM to −80 RPM at t = 4.0 s. The vector control causes the engine speed heading to be opposite in a natural manner., indicating its innovative capability to handle diverse operational scenarios. The MATLAB/Simulink package serves as the foundation for the proposed model, which is then integrated into OPAL-RT modules to create a Hardware-in-the-Loop (HIL) system for showcasing diverse outcomes. Different outcomes are deliberated with validated justifications of the suggested approach. The research is linked to Sustainable Development Goals 7 (Affordable and clean energy) and 13 (Climate action).

Effect of fuel compositions coupled with engine configuration parameters on a gasoline engine based on sensitivity analysis

ABSTRACT A gasoline engine is determined by many factors, the coupling of them makes it difficult to quantify the influence of each parameter on the gasoline engine. In order to find an effective way to improve the performance of a high-intensification gasoline engine, it is necessary to quantify the sensitivity factors of gasoline engines’ performance. In this paper, engine configuration parameters and fuel compositions were the inputs, and torque was the output. Models were developed by support vector machine for correlation analysis. Then, the models were used as agent models for Sobol sensitivity analysis to quantify the sensitivity factors of the engine performance. All the modeling results showed that the coefficient of determination was more than 0.9, and the mean absolute percentage error was less than 3%, indicating they were viable for sensitivity analysis. Sensitivity analysis results showed that the average influence weight of engine configuration parameters was 84.19%, much higher than that of fuel compositions. The two parameters with the most significant impact on engine performance are ignition timing and intake pressure, with average weights of 53.41% and 21.00%, respectively. With the increase of engine speed, the weight of intake pressure decreased, and the weight of ignition timing increased. Among the fuel compositions, the influence weight of oxygenated components was relatively higher. The effect of fuels with low combustion velocity on engine performance decreased with engine speed increased. In addition, there were interactions between the input parameters investigated in this paper, both ignition timing and intake pressure interacting most significantly with the fuel compositions at the engine speed of 5200rev/min. The second-order interaction accounted for about 90% of total interactions, indicating no need to consider higher-order interactions. In summary, support vector machine coupled Sobol method is feasible for sensitivity analysis in the field of internal combustion engine, which can effectively identify and quantify the role of each parameter itself and the interactions between the parameters under multi-parameter coupling and provide the basis and direction for the optimization of the gasoline engine.

Mixing-controlled compression ignition of ethanol using exhaust rebreathe at a low-load operating condition—Single cylinder experiments in a heavy-duty diesel engine

As pollutant emissions regulations in the heavy-duty sector become further stringent, the energy requirements in this sector continue to increase. Due to the high-power density and operating period requirements within this sector, full electrification is challenging. A viable solution to meet the stringent requirements for criteria pollutant and greenhouse gas (GHG) emissions is the use of low carbon renewable fuels. Low carbon renewable fuels are desirable due to their lower carbon content per unit energy compared to conventional fossil diesel fuel. However, implementing some low carbon renewable fuels in the heavy-duty sector poses challenges due to their low reactivity and the prevalent mixing-controlled compression ignition (MCCI) combustion strategy. Because of this, ignition assistance is needed to ignite low reactive renewable fuels in MCCI. This work investigates the use of a variable valve actuation (VVA) strategy, exhaust rebreathe, as an ignition assistance method to ignite pure fuel grade ethanol (E98) in MCCI. Exhaust rebreathe utilizes the hot combustion products from the previous cycle by reinducing the exhaust back into the cylinder during the intake stroke from a secondary exhaust valve event. The reinduction of exhaust into the cylinder increases the in-cylinder bulk gas temperature aiding in the ignitability of the low reactive fuel. The exhaust rebreathe strategy as an ignition assistance method is investigated in this work by conducting single cylinder engine experiments on a heavy-duty diesel engine fueled with E98. Exhaust pressure is varied for the exhaust rebreathe strategy to achieve combustion characteristics with E98 similar to diesel at a low-load, high engine speed operating condition. Additionally, an elevated intake air temperature strategy is implemented to compare to the exhaust rebreathe strategy as another form of ignition assistance with the objective to induce heat in-cylinder prior to combustion without the presence of diluent. Furthermore, zero-dimensional (0D) constant pressure chemical kinetic simulations are conducted to evaluate the most reactive conditions for ethanol to achieve ignition delay times similar to n-heptane. The experimental results demonstrate that at a high speed, low load condition—the elevated intake air temperature strategy with ethanol requires 120°C intake temperature to yield an ignition delay similar to diesel. When accounting for the energy required to heat the intake air, the brake thermal efficiency is 40% lower than the diesel baseline. On the contrary, the exhaust rebreathe strategy with an exhaust pressure of 1.5 bar-a, is able to achieve the same ignition delay with an MCCI combustion process but maintain a brake thermal efficiency within 5% of the baseline diesel engine.

Experimental investigation of Gyroid recuperator performance integrated with internal combustion engine

The recuperator has the potential to enhance engine performance, reduce fuel consumption, and lower pollutant emissions, making it a promising technology for promoting environmental sustainability. This study investigates the impact of a Gyroid recuperator on the performance of a four-stroke internal combustion engine. Experimental analyses compared engine performance at various set points of rotational speeds before and after recuperator installation. The results validate the effectiveness of the Gyroid recuperator in recovering waste heat, thereby leading to improvements in fuel efficiency. The optimal performance, characterized by an 832.31 J/s increase in recovered combustion heat energy, was observed at 7000 RPM. Additionally, the Gyroid recuperator achieved a maximum overall heat transfer coefficient of 7.9215 W/m2 K at 8000 RPM. The performance of the Gyroid recuperator was further analyzed using the log mean temperature difference method, which yielded a peak value of 114.4 °C at 7000 RPM. The effectiveness-number of transfer units’ method was also employed to assess its effectiveness. These results show that the recuperator can efficiently transmit and recover heat under certain working circumstances. The analysis suggests higher heat energy losses at lower speeds than high speeds, indicating a more efficient energy conversion process at higher engine speeds. The possibilities of the Gyroid recuperator to improve engine performance and its suitability for internal combustion engines are highlighted in this study. This technology offers a promising solution for improving vehicle efficiency and promoting environmental sustainability.

Response Surface Optimization of Vibration Level in Diesel Engine with Biodiesel Usage: A Performance Enhancement Study

In this study, a single-cylinder direct-injection (DI) diesel engine was fueled by biodiesel. The Palm Oil Methyl Ester (POME), blended in amounts up to 20%, is tested at various engine speeds and loads to measure vibration level. Then, mathematical modeling was developed to relate the engine vibration level's responses to variables, including engine speed, load, and biodiesel blending percentage. Finally, all the numerical factors were calibrated using the proposed models. The significance of all factors in this study was demonstrated by the second peak of the engine's vibration, which contains a wealth of information about the excitations. Modeling results had previously shown that the significance of factors could vary according to the corresponding peaks of vibration in the engine. Meanwhile, the adjusted R2 of the developed model for vibration responses were 0.98, 0.87, 0.76, and 0.79, respectively. Further, the optimization results highlighted that utilizing a B20 fuel blend—a mixture of 20% biodiesel and 80% diesel fuel by volume—run at 2160 rpm with no load condition produced the best solution with the highest desirability value to satisfy all the responses. In summary, the study's findings showed that optimization should be considered while developing a new policy for using biofuel in internal combustion engines.