Four-stroke Engine Research Articles

Effects of ozone addition on the kinetics and efficiencies of methane conversion at fuel-rich conditions

Compression–expansion processes have the potential of converting mechanical work to chemical energy at fuel-rich conditions, allowing for the storage of fluctuating renewable energies. In this work, the conversion of methane and natural gas (NG) is investigated for this purpose. A focus is on using ozone as a reaction promoter for the otherwise slow reaction. The kinetics of fuel-rich methane/NG oxidation with ozone addition is investigated experimentally and numerically. To this end, ignition delay times (IDTs) for CH4/O2/O3/Ar and NG/O2/O3/Ar mixtures are measured in a rapid compression machine (RCM). It is shown that a reaction mechanism obtained by simply combining a previously developed mechanism for methane conversion (PolyMech2.0) with an ozone sub-mechanism does not accurately predict IDTs. Sensitivity analyses identify reactions in the methane submechanism that become more important for ignition delay time when ozone is added in comparison to mixtures without O3. The rate coefficients of these reactions are modified within their uncertainty ranges to better match the experimentally obtained IDTs. The resulting kinetic model, named PolyMech 3.0, predicts the IDTs obtained in RCM-experiments well. Analysis reveals a two-fold promoting effect of ozone addition on methane/air ignition: Ozone causes a temperature rise by the reactions associated with its decomposition. Ozone also forms reactive products such as hydrogen and oxygen radicals, which can then promote reactions of the hydrocarbons. Quantitative analysis shows that the latter effect is more pronounced. Using PolyMech 3.0, parametric simulation studies for methane conversion in four-stroke engine cycles are carried out to explore the effects of ozone addition on chemical energy storage and efficiencies of engine-based polygeneration processes. Results show that with ozone addition, methane conversion can take place at high engine speeds, while without ozone, there is nearly zero conversion of fuel rich methane mixtures because of the low reactivity. Therefore, ozone addition allows for reasonable efficiencies across a wider range of operating conditions.

Effective Parameters of a Compression-Ignition Engine Powered by a Mixture Consisting of Ethyl-Tetra-Butyl Ether and Diesel Fuel

The present article presents the results of analytical research on the possibility of using a mixture consisting of diesel oil and ethyl-tertiary-butyl ether in different percentages of EETB to power compression-ignition engines. The calculations were carried out for a four-stroke diesel engine intended for use as a power generator, among other things. In order to illustrate and verify the correctness of the calculations, a mathematical model was built that confirmed the correctness of the calculations. The calculations focused on a thorough analysis of the elemental composition (content of individual elements) of the fuel and, in particular, the carbon content in the fuel. A calculation algorithm was applied for mixing diesel fuel with ethyl-tertiary butyl ether in a share of EETB 5% + 95% ON, 10% EETB + 90% ON, 20% EETB ++80% ON, 30% EETB + 70% ON, 40% EETB + 60% ON. In this study, it determined the parameters of the working medium, the parameters of the environment and residual gases, and the processes (charge filling, compression, combustion, expansion) and effective parameters of the engine. The calculations used in this study led to heat balance, and a summary of the obtained results and their comparison with diesel oil are also described in this study. The results show the feasibility of using a mixture of ethyl-tertiary-butyl ether as a fuel in diesel engines. The results are very similar to those for 100% diesel. The results of our calculations confirming the possibility of using ether for fuel and thus maintaining similar engine operating parameters.

Investigations on performance parameters of carburetted butanol and plastic oil

As fuel prices continue to rise and pollution levels caused by fossil fuels escalate, there is a growing recognition of the importance of alternative fuels. Alcohols and vegetable oils are particularly promising as substitutes for diesel fuel due to their renewable properties. However, both vegetable oils and alcohols have certain drawbacks, such as high viscosity and low volatility for vegetable oils, and low energy content and Cetane number for alcohols. To address these challenges, the use of semi-adiabatic diesel engines (SADE) has been proposed. In this study, the focus was on evaluating the performance characteristics of both a conventional engine (CE) and a semi-adiabatic diesel engine (SADE). The engines were powered by a combination of carbureted butanol and injected plastic oil, leveraging the high energy content of plastic oil and the high volatility of butanol to achieve lower pollution levels. The objective was to assess the effectiveness of these engines in mitigating environmental impact The experimental engines utilized carbureted butanol and injected plastic oil, with variations in injection timing and pressure. The engine used in the study was a water-cooled, single-cylinder, four-stroke engine with a ceramic-coated cylinder head. It had a rated output of 3.68 kW at 1500 rpm. Measurements of various engine parameters, including thermal brake efficiency, brake specific energy consumption, exhaust gas temperature, coolant load, and volumetric efficiency, were conducted under full load conditions. To modify the injection timing, an adjustable sensor was employed, while a variable jet carburetor mounted at the engine's inlet manifold controlled the rate of carbureted butanol. Injection pressure was adjusted using a spout testing instrument, and conventional injection was utilized for the crude plastic oil.

Study on the performance characteristics and failure analysis of exhaust valves

Abstract Exhaust valves are a type of valve that can commonly be found in the top section of the cylinder block in an engine. When failures occur on the exhaust valve, the engine has a high possibility to result engine failure or breakdown. This will affect the user where the user requires to spend a huge amount on repairing costs or engine replacement. Thus, this research aims to investigate the effect of the exhaust valve’s material on its performance and identify the appropriate material which could increase its fatigue life in a four-stroke internal combustion diesel engine. A three-dimension (3D) Computer-aided design model of the exhaust valve was generated by using SOLIDWORKS and undergo static structural analysis as well as thermal analysis. The measure variables are von-mises stress, total deformation, temperature, total heat flux and directional heat flux by using ANSYS Finite Element Analysis. Stainless steel 304 alloy and Aluminium-Silicon Carbide (Al-Sic) materials are the manipulated variable that was applied to the 3D CAD model exhaust valve to undergo all the analyses. Before performing all the analyses, the appropriate mesh method and mesh sizing was identified by referring to the mesh metrics spectrum and performing a mesh independence test. The results from the analysis were collected and tabulated for comparison and discussion purposes. From the analysis, the maximal thermal stress was determined in the valve stem region. By appointing Stainless Steel 304 alloy on the exhaust valve, the durability and the fatigue life are improved as the material can achieve a smaller value of temperature distribution, total heat flux, total deformation, and higher von-mises stress. This research provided a better understanding of the effect of an exhaust valve material on its performance characteristic.

Influence of varying concentrations of TiO2 nanoparticles and engine speed on the performance and emissions of diesel engine operated on waste cooking oil biodiesel blends using response surface methodology

For a few decades now fast depleting fossil fuels has been a major challenge. Fast expanding population and increased rate of urbanization has increased energy demand. This makes the current scenario worse. Fossil fuels' emissions are another challenge. Apart from fossil fuel emissions, the untreated disposal of waste cooking oil presents another environment’s sustainability challenge. The treatment of waste cooking oil as fuel presents a tangible solution to challenge. In this research article, impact of the engine speed and the concentration of titanium dioxide (TiO2) nanoparticles (NPs) in diesel-biodiesel blended fuels on the engine’s performance. The emission characteristics of a single-cylinder four-stroke diesel engine has also been examined. TiO2 NPs were produced by a sol-gel methodology. The diesel-biodiesel combination was fortified with TiO2 NPs at 40, 80 and 120 ppm. These mixtures were used to power the diesel engine, which was then run at 1150, 1400, 1650, 1900 and 2150 RPM. Interaction between engine speeds and nanoparticle concentrations and investigation of their combined effect on engine performance and emissions was done using response surface methodology. The minimum BSFC of 0.33994 kg/kWh and maximum BTE of 25.90% were found for B30 + 120 ppm biodiesel blend at 2150 rpm as compared to all other tested fuels. The emissions including CO and HC emissions were recorded as 25.61486 kg/kWh and 0.05289kg/kWh respectively at 2150 rpm for B30 + 120 ppm biodiesel blend while NOx on the contrary side exhibits a slight escalation with increasing engine speed and nanoparticles concentration. The findings of the experiments demonstrated that adding TiO2 nanoparticles to diesel–biodiesel blends is an effective way to enhance the performance of diesel engines while simultaneously reducing the emissions. It was also discovered that the mathematical model that was built can efficiently estimate the performance of the engine and the emission levels.

Effect of Pilot Injection Strategy on Performance of Diesel Engine under Ethanol/F-T Diesel Dual-Fuel Combustion Mode

To reduce emissions and save energy, alternative fuel and dual-fuel mode have been widely applied in the field of diesel engines. The pilot injection has potential to reduce engine vibration noise and pollutant emissions. The effects of a diesel fuel pilot injection strategy on the performance of an ethanol/F-T diesel dual-fuel engine were experimentally investigated on a four-cylinder four-stroke common rail diesel engine modified with an ethanol injection system. The results indicate that the variation in the combustion characteristic parameters with pilot injection timing is nonlinear and the difference is small, while soot, NOx, and CO tend to decrease, with an increase in pilot injection timing. With the increase in pilot injection amount, pmax, combustion duration, CO and soot increased; pmax phase and CA50 were closer to TDC; HRRmax and the ignition delay period decreased. The BSFC tends to increase with the increase in pilot injection timing and the increase in pilot injection amount, while the BTE shows the opposite trend. The value and the variation range of COVpmax are small. The effect of the pilot injection amount on ethanol/F-T diesel dual-fuel engine is more significant. The research presented in this paper can provide reference directions for the formulation of a fuel injection strategy of ethanol/F-T diesel dual-fuel combustion mode to reduce NOx without worsening the combustion process and presenting an insufficient fuel economy.

Investigations on the performance, emission and combustion characteristics of a dual-fuel diesel engine fueled with induced bamboo leaf gaseous fuel and injected mixed biodiesel-diesel blends

The present paper briefly elaborates upon the combination of waste palm and waste sunflower oil methyl ester as post-mixed biodiesel blends being injected into a four-stroke compression ignition engine, which is also fueled with inducted bamboo leaf generated producer gas (BLP.gas) that includes gaseous components of CO (carbon monoxide), H2 (hydrogen), CH4 (methane), and CxHy (hydrocarbons). The objective of the present research is to evaluate the overall performance, emission, and combustion behavior of a Kirloskar TAF1 modified dual-fuel diesel engine fueled with induced bamboo leaf-derived gaseous fuel at a fixed mass flow rate of 21.69 kg/h and injected mixed biodiesel-diesel blends. Initially, diesel fuel and post-mixed methyl ester were examined in dual-fuel mode with a fixed gas flow rate for different loads. It can be seen from the analysis that brake thermal efficiency got reduced by 4.66% and brake-specific fuel consumption increased by 5.26% for PMOME20 (20% post-mixed oil methyl ester + 80% diesel fuel) + BLP. gas with respect to diesel fuel at extreme loading conditions. Moreover, smoke opacity, carbon monoxide, and unburnt hydrocarbons were reduced by 11.22%, 20.44%, and 10.36%, respectively. On the other hand, oxides of nitrogen were reduced by 19.17% at maximum load for PMOME20 + BLP. gas in dual-fuel operation in contrast to that of petroleum diesel. In light of this, the current research concluded that the use of biodiesel and BLP. gas for dual-operative engines may be regarded as an appropriate option for reducing pollutant environment and petroleum fuel scarcity.

Impact of Diethyl Ether on Performance and Emission Characteristics of a VCR Diesel Engine Fueled by Dual Biodiesel

Biodiesel is widely known as the alternative fuel for the diesel engine, but it comes with its fair share of challenges. To minimize the pertinent drawbacks, fuel additives become an essential tool and help improve renewable fuel’s properties. In this current research, biodiesel is obtained from rice bran oil and cotton seed oil, with diethyl ether as an additive. Diethyl ether is known for good oxygen content, high cetane number, and low viscosity. Experiments were performed on a variable compression ratio engine at a compression ratio of 18:1, and the injection pressure (170 bar, 180 bar, 190 bar and 200 bar) and the injection timing (20, 21, 22 and 23°bTDC) with four different dual biodiesel blends (5%, 10%, 15% and 20% by volume). Different ratios of 1%, 2.5% and 5% of diethyl ether with biodiesel combination were examined in a single-cylinder, four-stroke diesel engine. The engine emission and performance features were discussed at different loads and constant engine speeds. It was observed that using 5% of diethyl ether with biodiesel blends improved brake thermal efficiency, brake-specific fuel consumption and decreased carbon dioxide and oxides of nitrogen emissions. The reduction of oxides of nitrogen emission contributes to biodiesel’s acceptability for the environment’s benefit. This investigation found that diethyl ether, along with dual biodiesel blends, has a better viability in diesel engines.

Newly developed detailed urea decomposition mechanism by marine engine urea-SCR system crystallization test and DFT calculations

The problem of urea crystallization in selective catalytic reduction (SCR) systems has been a concern for a long time, especially in vehicle engine after-treatment. Compared with the vehicle engine SCR system, the layout space of the marine engine SCR system is more spacious, but the impingement of urea-water solution (UWS) on the wall as well as the formation of urea deposits still cannot be avoided in many cases. In this paper, the urea deposits in the SCR systems of 10 MW marine two-stroke and 140 kW marine four-stroke engines are taken as the research objects. The research results showed that the composition of urea deposits is affected by the composition of exhaust gas. Besides biuret, ammelide, cyanuric acid (cya) and its homologues, the urea deposits contain non-urea decomposition by-products such as particulate matter (PM) and sulfate. In addition, most of the existing urea decomposition mechanisms are obtained by inferring the intermediate reaction pathways through thermogravimetric analysis (TGA), which has the disadvantage of kinetic parameters being inaccurate calculation due to oversimplified reactions, and cannot explain the coexistence phenomenon of cya and its homologues in the urea deposits of marine SCR systems. Therefore, based on density functional theory (DFT), a new detailed urea decomposition mechanism is proposed in this paper, including 15 species and 23 reactions. This mechanism introduces homologues of urea, biuret, and triuret, complementing the reaction pathways for forming cya and its homologue, and is more reliable in theory. On this basis, the correctness of the proposed urea decomposition mechanism is validated by using the TGA experimental data of urea deposits and the urea decomposition kinetic model, and machine learning.

Working Performance and Feasibility Evaluation of Four-stroke Compressed Air Engine

ABSTRACT Research on compressed air engine (CAE) is of great value under the background of energy conservation, emission reduction, and environmental protection in recent years. Compared with traditional internal combustion engine (ICE), four-stroke compressed air engine (F-s CAE) has no combustion and explosion process during operation, and the use and emission of working medium is clean air. Here, to deeply discuss the working performance of the F-s CAE, first, we expound a working principle of the F-s CAE. In addition, we analyze the control strategy of the electronic control unit (ECU) system and carry out a calibration test for the CAE. Meanwhile, we further conduct a feasibility analysis to verify its scientificity as the power of means of transport. In the test process, engine speed, supply pressure, port timing (intake advance angle and intake sustain angle) can directly affect the working performance. Results suggest that the overall effective power and single cylinder compressed air consumption increase with increase in the engine speed, while the average effective torque changes oppositely. Kinetic and dynamic characteristics are much better after supply pressure increased. The dynamic performance improves with the decrease in intake advance angle, but subsequently goes down when the intake advance angle decreases from 10°CA to −90°CA, and the intake advance angle as −70°CA is optimal. Overall, an intake sustain angle of 80°CA is more conducive to improving CAE dynamic performance compared to a relatively small intake sustain angle. The research results will be useful for further design and improvement of the F-s CAE.

Alternative Surface-Mounted Permanent Magnet Topology for Reducing Voltage and Torque Harmonics in Shaft Generators

Traditional diesel generators on a merchant ship, composed of a wound rotor synchronous generator and a four-stroke diesel engine, supply electrical power for various loads. Recently, shaft generators for merchant ships have been increasingly replacing diesel generators to reduce CO2 emissions through fuel efficiency improvement. In particular, permanent magnet synchronous generators have replaced induction generators due to their high-efficiency characteristics at light loads. The surface-mounted permanent magnet rotor can be a suitable topology owing to the relatively short constant power range. This generator can also operate as a motor according to the propulsion mode, so minimizing the harmonics of the induced voltage with the torque pulsation being essential. This paper proposes an alternative surface permanent magnet topology. Three magnets comprise one pole, with one bread-loaf magnet and two rectangular magnets. It helps to simplify the magnetization and assembly of the rotor because of the flat bottom shape of the magnet. Due to the low remanence of two rectangular magnets at the pole edge, this rotor structure effectively makes the air-gap magnetic flux density sinusoidal with production costs reduced. The step-skew suppresses higher-order harmonics. The total harmonic distortion comparison of the two-dimensional finite element analysis and the no-load test result shows under 6% difference from the interior permanent magnet prototype machine. A comparison of harmonic characteristics with other rotors shows that the proposed modular pole has sufficient competitiveness compared to the tapered bread-loaf type. It can be applied as a substitute for the tapered bread-loaf magnet in direct-drive ship propulsion systems and is expected to shorten the manufacturing process and time.

Review of Biofuel Effect on Emissions of Various Types of Marine Propulsion and Auxiliary Engines

The International Maritime Organization aims to reduce the maritime industry’s carbon emissions by 40% in the next two decades and has introduced measures to control CO2 emissions. These have significantly increased interest regarding biofuels, which can be used immediately on existing vessels, reducing their carbon footprint. The most common variant is B30, a blend of 70% crude oil and 30% biodiesel. Concerns exist for the potential effect on engine performance and NOx emissions. Scientific works on the subject are limited for two-stroke marine engines, while some studies are available for four-stroke ones, usually auxiliaries. To increase information availability on the subject, in this work, we review the results of testing on multiple marine engine types, two-stroke propulsion and four-stroke auxiliary units using B30 and conventional fuels. The effect on emissions and fuel efficiency is examined and cross-referenced with the available literature. A small increase in specific fuel consumption was observed for B30 use that varied with engine type. The increase was on average 1% for two-stroke and 2.5% for four-stroke engines. The effect of B30 on NOx emissions was low but varied between engines. For low-speed two-stroke engines, NOx increase was on average 4% compared to crude oil, and 2.4% for four-stroke auxiliary units, albeit with higher variance. For some four-stroke units, a decrease in emissions was found. All previous results were in line with other published studies. Overall, it was found that while biofuel effect can vary considerably between applications, 30% biodiesel blends can be used with no concerns regarding emissions and fuel efficiency.

Effect of Variations in Velocity Air Intake Cyclone Dimensions on Motorcycle Torque and Power

The Velocity Air Intake System is an important component in a motor vehicle engine, particularly in a 155cc engine. Its function is to optimize the airflow process to the throttle body or carburetor. However, many users or people tend to overlook the significance of improving engine performance by varying the model or replacing the velocity air intake system itself. One common issue is the diameter and shape of the airflow model, which can affect the power, torque, and exhaust emissions produced. Installing a velocity air intake system is one approach to achieve an efficient air delivery process into the combustion chamber. In our research conducted using a dyno test on a 155cc four-stroke engine, the results showed that using a 46 mm size yielded the highest power of 11.03 Hp and produced a torque of 12.39 N.m. Using a 47 mm size resulted in 11.02 Hp and decreased the torque to 12.28 N.m. With a 48 mm size, there was a decrease in power to 11.00 Hp and an increase in torque to 12.72 N.m, while using a 45 mm size led to a decrease in power to 10.09 Hp and produced a torque of 11.31 N.m.

Synthesis and characterization of calcium oxide nano particles obtained from biowaste and its combustion characteristics in a biodiesel operated compression ignition engine

The goal of this research is to use calcination to make calcium oxide (CaO) nano additives that can be used as fuel additives. Spectrum investigations using X-ray Diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) established the synthesis of nano particles. The fuel is a waste cooking oil bio diesel of B20 blend (20% biodiesel and 80% diesel) mixed with nano Calcium oxide additives in five concentrations: 25, 50, 75, 100 and 125 ppm. The qualities of the fuel are examined in line with the criteria of the American Society for Testing and Materials (ASTM). The combustion investigation of these fuel samples in a four-stroke compression ignition engine coupled to an eddy current dynamo-meter found a 3% improvement in average brake power. All of the fuel samples examined have a combustion efficiency of 90–98%. The CaO nano additions improved the heat release rate (HRR) of the engine. The average cylinder pressures (CP) of the additive blended samples are also higher. Peak pressures of the biodiesel samples investigated in the experiment ranged from 1° to 15° crank angle after top dead centre (aTDC) under all conditions. The mean pressure rise rate (MPRR) for WCOB20 + CaO25ppm is 4.7 bar/degree CA. According to this study, the synthesised micro CaO particles appear to be a viable candidate for usage as additives to improve the combustion characteristics of engines powered by bio-diesel blends. However a complete study on performance, emission along with combustion characteristics is required to evaluate the prominence of this fuel with prepared nano additives. In future, calcium oxide nano catalysts for the production biodiesel may also be an viable alternate.

Fundamentals and Some Results of Numerical Modeling the Cylinder-Piston Group Jet-Oil Supply in a High-speed Four-Stroke Internal Combustion Engine

Fundamentals and Some Results of Numerical Modeling the Cylinder-Piston Group Jet-Oil Supply in a High-speed Four-Stroke Internal Combustion Engine

Classification of transient vibration of passenger cars powertrain

This work is a study on transient vibrational behaviour of a vehicle driveline system during tip-in/released/tip-out throttle. The considered vehicle is a passenger sedan, front-wheel drive, front-engine equipped with a four-stroke four-cylinder SI engine and a 5-speed manual transmission. The engine's model follows the mean value model including the effects both dynamics and combustion parameters including manifold/engine volume, air to fuel ratio, spark advance/retard and RPM on its transient indicator and brake torque behaviour. A primary fourteen-degrees-of-freedom lumped parameter torsional driveline model including, a multi-staged clutch with nonlinear clutch springs model and the gear backlash effect on idle as well as engaged gears is considered. This model is reduced to a six-degrees-of-freedom model. A rigid 2D model and magic formula are used for modelling of vehicle-tyre-road dynamics interaction. Using the overall model, the role of the driving style, the engine dynamics and longitudinal vehicle-road dynamic interaction in creating and intensifying the shuffle, clonk, and shunt, are studied and summarized, as the particular focus of this study. Although the results verify the other related researches on the importance of nonlinear parameters such as nonlinear stiffness, backlash and gear teeth impact, on the intensity of vibro-impact responses, they prove that engine's dynamics/combustion parameters such as engine volume, intake manifold volume and spark advance timing as well as driving style and also tyre-road parameters such as coefficient of friction and road grade have significant role in intensifying the vibro-impact responses. For example, (a) the smaller the engine, the larger amplitude the shuffle; (b) the sport driving style intensifies the both the clonk and the shuffle and (c) the more slippery road in time of the tip-out, the more strengthen the shuffle. The results of the overall driver/engine/driveline/tyre/road model provide more knowledge towards better understanding of vibro-impact response of the driveline.

Analysis of fuel properties in the context of the causes of three marine auxiliary engines failure – A case study

This article presents the effects of a severe failure of three four-stroke auxiliary engines in a container ship’s power plant. The failure included jammed cylinder valves, fuel equipment damage, a fire in one of the engines and an explosion of its turbocharger. An analysis of fuel as a factor that constitutes the source and common cause of failure of each engine is made. Laboratory analysis of the fuel is performed. Auxiliary indicators describing the fuel properties are determined, including the calculated carbon aromaticity index (CCAI) and the calculated ignition index (CII). Laboratory analysis of the fuel ignition properties, including the determination of the equivalent cetane number (FIA CN and ECN) and the delay of self-ignition in test conditions (ID). The possible causes of non-compliance with quality standards by the fuel used to power the damaged engines before and during the failure are consulted. Recommendations that may improve safety are presented.

Study on selected parameters of engine with the active combustion chamber

The present study was focused on the combustion engine with a variable compression ratio (VCR), namely the four-stroke air-cooled engine with the active combustion chamber (ACC). An indicated pressure, torque, power, and specific fuel consumption of that engine were investigated experimentally as a goal of the present study. Experiments were conducted using two versions of an engine. Two parameters particularly influencing the ACC engine performance including the maximum compression ratio CRmax and the indicator γfm determining the correct operation of the ACC system, were described. It was found that the ACC engine allowed avoiding detonation combustion without changing the amount and composition of the combustible mixture, and even without delaying the ignition advance angle. In addition, the possible range of control of the combustion process allowed the ACC engine to operate with different types of hydrocarbon fuels, for example, in the form of petrol with various alcohol admixtures . The very intense flow of the combustible mixture inside the cylinder of the ACC engine allowed describing the combustion in the ACC engine with zero-dimensional mathematical models with the dual Vibe function providing the proper characterization of the heat release process. The use of very high maximum compression ratios allows the ACC engine to operate to a certain extent as a Homogeneous Charge Compression Ignition (HCCI) engine with high lambda coefficients.

Performance improvement and CO and HC emission reduction of variable compression ratio spark-ignition engine using n-pentanol as a fuel additive

This study tests binary and ternary n-pentanol, ethanol, and petrol blends to increase spark-ignition (SI) engine performance and minimize CO and HC emissions. To improve brake thermal efficiency (BTE) and reduce emissions, adding ethanol into gasoline is one of the practices used in Automobiles. But the literature reported some performance limitations and problems with adding a high ethanol concentration to gasoline as phase separation problem occurs in fuel tank due to the hygroscopic nature of ethanol, a higher ethanol concentration may corrode some parts of the fuel supply system. Ethanol has a lower calorific value than gasoline, so a higher ethanol concentration in blends beyond a specific limit reduces BTE. N-pentanol as a fuel additive in gasoline can better solve these problems due to its high caloric value compared to ethanol. Also, when n-pentanol is mixed with gasoline and exposed to moisture, it does not separate in stages as in the ethanol case. Accordingly, this research aims to evaluate n-pentanol's viability as a fuel additive in petrol and ethanol-gasoline blends at different compression ratios. The experiments were carried out on a single-cylinder, four-stroke spark-ignition engine running at a constant speed. Different blends of n-pentanol with gasoline and ethanol were tested, and results were compared against gasoline and E10 (the optimal blend of ethanol-gasoline, 10/90 v/v %). Various parameters were examined, including BTE, brake-specific fuel consumption (BSFC), and different exhaust pollutants. The effects of compression ratio values on these parameters were also recorded. The 1.5 vol% pentanol with E10 (E10P1.5) mix has the best overall characteristics, including low BSFC, high BTE, and low CO and HC emissions compared to petrol and E10 fuels. E10P1.5 shows a maximum enhancement in BTE, low BSFC, CO reduction, and HC reduction by 23.79%, 19.80%, 37.79%, and 19.46%, respectively, over gasoline. Compared to E10, the improvement is 3.64% for BTE, 4.59% for BSFC, 8.88% for CO emission reduction, and 4.13% for HC emission reduction.

Challenges and feasibility of a six-stroke engine using water direct injection

As fuel efficiency and exhaust regulations have become more stringent, many studies have been conducted to improve fuel efficiency. One interesting proposal is to develop a six-stroke engine using water injection. However, there is a lack of research on this concept, and existing studies have only taken a theoretical approach or did not involve comparisons with a four-stroke engine, obscuring the feasibility of a six-stroke engine using water injection. So, in this study, we performed experiments and simulations of a six-stroke engine using water injection and compared the results with those of a four-stroke engine. We optimized the exhaust valve lift profile through simulation for an actual exhaust cam of the six-stroke engine, and modified a four-stroke port fuel injection engine to a six-stroke engine. Then, through experiments and simulations, we evaluated the feasibility and the challenges of building a six-stroke engine using water injection. We used the CONVERGE v2.4 software application and validated the simulation models through the results of experiments. Using these models, we conducted simulations with various injection timings, masses, and water temperatures. The results indicate that the cylinder wall is cooled due to continuous water injection making evaporation unstable and that wall-temperature control is required in order to realize a six-stroke engine using water injection. In a simulation assuming the constant temperature of the wall, as additional strokes are added, the indicated mean effective pressure (IMEP) decreases by about 0.4 bar compared to that of the four-stroke engine, and only about 40% of this loss is recovered through water injection. The wall evaporation ratio is more critical to the feasibility of the six-stroke engine using water injection than other parameters. We show that it is very difficult to achieve a six-stroke engine using water injection unless a significant amount of heat energy for evaporation is brought from sources other than the mixture in the cylinder. The challenges of a six-stroke engine using water injection were cylinder temperature control and latent heat of water. If excessive cooling does not occur, such as in steam injection, IMEP can increase due to an increase in mass. However, this is very ideal case. It is difficult to obtain energy elsewhere for evaporation, and due to the latent heat of water, the mixture is inevitably cooled down making it difficult to realize this concept of six-stroke engine.