Search

This study examines the effects of methanol–diesel blends on the emissions of a diesel engine, concentrating on carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), hydrocarbons (HCs), and particulate matter (PM). Using a single-cylinder four-stroke diesel engine at varying torque settings (2 N m–6 N m), significant reductions in CO, CO2, HC, and PM emissions were observed with increasing methanol content. CO emissions reduced by up to 81.8%, CO2 by up to 64.2%, HC by up to 80.4%, and PM by up to 23.5% with the MD11 blend. NOx emissions initially increased but decreased by up to 20% at higher torques with the same blend. These results highlight the environmental benefits of methanol–diesel blends and the need for effective NOx reduction strategies. [ABSTRACT FROM AUTHOR]

The development of fast and strong microactuators that can be integrated in microdevices is an essential challenge due to a lack of appropriate driving principles. A membrane actuator powered by internal combustion of hydrogen and oxygen in a chamber with a volume of 3.1 nanoliters is demonstrated. The combustion in such a small volume is possible only for an extremely high surface‐to‐volume ratio on the order of 107 m−1. The fuel with this ratio is prepared electrochemically in a special regime that produces only nanobubbles. A cloud of nanobubbles merges, forming a microbubble, which explodes, increasing the volume 500× in 10 µs. The actuator generates an instantaneous force up to 0.5 N and is able to move bodies 11 000× more massive than itself. The natural response time of ≈10 ms is defined by the incubation time needed to produce an exploding bubble. The device demonstrates reliable cyclic actuation at a frequency of 1 Hz restricted by the effect of electrolyte aging. After 40 000 explosions, no significant wear in the chamber is observed. Due to a record‐breaking acceleration and standard microfabrication techniques, the actuator can be used as a universal engine for various microdevices including microelectromechanical systems, microfluidics, microrobotics, wearable and implantable devices. [ABSTRACT FROM AUTHOR]

This study examines the effects of methanol–diesel blends on the emissions of a diesel engine, concentrating on carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), hydrocarbons (HCs), and particulate matter (PM). Using a single-cylinder four-stroke diesel engine at varying torque settings (2 N m–6 N m), significant reductions in CO, CO2, HC, and PM emissions were observed with increasing methanol content. CO emissions reduced by up to 81.8%, CO2 by up to 64.2%, HC by up to 80.4%, and PM by up to 23.5% with the MD11 blend. NOx emissions initially increased but decreased by up to 20% at higher torques with the same blend. These results highlight the environmental benefits of methanol–diesel blends and the need for effective NOx reduction strategies.

The Jerusalem artichoke (Helianthus tuberosus) is a high-yield crop, and a great source of fermentable sugars, which gives the plant the potential to be used as raw material for economical fuel alcohol production. In this article, the authors focus on the technological aspect of the biofuel manufacturing process and its properties. First, the fuel alcohol manufacturing process is described, afterwards assessing its characteristics such as kinematic viscosity, density and octane number. The amount of fuel alcohol obtained from 10 kg of biomass equals to 0.85 L. Afterwards, the mixtures of gasoline and obtained fuel alcohol are prepared and studied. Optimal alcohol and gasoline mixtures are determined to obtain biofuels with octane ratings of 92, 95 and 98. The kinematic viscosity of obtained mixtures does not differ significantly from its values for pure gasoline. The obtained biofuel mixture with 25% alcohol content yielded a decrease of sulfur content by 38%, an increase of vaporized fuel amount by 17.5% at 70 °C and by 10.5% at a temperature of 100 °C, which improves engine startup time and ensures its stable operation in comparison to pure gasoline. The alcohol obtained can be successfully used as a high-octane additive for gasolines. [ABSTRACT FROM AUTHOR]

The tribological performance of internal combustion engines (ICEs) has an important impact on fuel efficiency and power consumption, and the wear of cylinder liner-piston ring (CLPR) system affects the operation reliability. The surface texture of CLPR can significantly improve the tribological performance of ICEs. Aiming at the friction and wear of CLPR, the different textures (dimple, equilateral triangle and square) are generated on the CLPR using laser processing, and the different tests are conducted on the UMT-TriboLab tester. The coefficient of friction, wear topography, surface roughness parameters and profiles are measured. The results show that, compared with the non-textured surface, the dimple texture surface of piston ring or cylinder liner has better tribological performance. If the textures coexist on the cylinder liner and piston ring, the tribological performances are better than single surface texture. Furthermore, the mixed textures can significantly improve the surface lubrication performance and the ability to store abrasive particles, and better surface quality can be obtained at the same operating conditions to enhance the tribological performance. This study can provide guidance for reducing the friction and wear of CLPR system of ICEs, and achieve energy saving and emission reduction of ICEs. [ABSTRACT FROM AUTHOR]

Hydrogen energy has been assessed as the clean and renewable energy source with the highest energy density. At present, 25% of energy demand comes from the transport sector, while 20% of greenhouse gases are produced from the transport sector at the global level. Hydrogen may be utilized in the vehicles as a fuel for fuel cell vehicles or as a hydrogen system in internal combustion engine vehicles. In both cases, hydrogen storage remains a key parameter. Various types of hydrogen storage materials have a wide range of operating conditions in terms of temperature, hydrogen plateau pressure, and hydrogen storage capacity with other relevant hydrogenation characteristics. At present, not a single hydrogen storage material is available to fulfill all the requirements of hydrogen storage for vehicles on the set target of DOE US. MgH2 has high hydrogen storage capacity equivalent to 7 wt%, but desorption temperature is 300°C. The normal vehicles do not operate at such a high temperature. Therefore, in the present communication, combinations of metal hydrides have been studied. The first combination belongs to MgH2 and AB2 system and another belongs to MgH2, NaAlH4, and AB2 system. In the calculation performed, it has been shown that the amount of heat and temperature available in the exhaust gas of a vehicle is enough to liberate the hydrogen from the high‐temperature metal hydride system. The calculated specific capacity on the system basis has been found as 1.13 kWh/kg (0.034 kgH2/kg) and 1.20 kWh/kg (0.036 kgH2/kg) for both combinations, respectively. These values of specific capacity are very much close to the present target of DOE US. [ABSTRACT FROM AUTHOR]

The importance of gas turbine engines to the aviation industry cannot be overemphasized. Being a major part of aircrafts and jets, its reliability must be second to none. They are continuously subjected to extreme conditions during service making them the subject of constant studies. To produce the thrust and torque power required of them, they have to convert the intense heat and pressure inherent in hot combustion gases. To withstand the high combustion gas temperature without thermal failure, specialized materials and cooling are employed. This study numerically investigated the effect of cooling fluid temperature on the structural integrity of a (DS) GTD111 alloy gas turbine stator blade using COMSOL 5.5 software. Air was used as the cooling fluid in this study. The duct passages of the stator blade are significantly affected by the cooling fluid temperature values. Lower values of cooling fluid temperature proved beneficial for keeping the stator blade material below its metallurgical limit and is a positive for its total displacement, it however, negatively affects the yielding of the material. The cooling fluid temperature can be optimally selected to give optimal cooling effects in terms of total displacement and stress development. Based on this study, a cooling fluid (air) temperature of about 660 K will give optimal results. Internal cooling alone is not sufficient to produce the required cooling for turbine stator blades and this is evident in the output of the study, thus, coating and film cooling must be carried out to prevent thermal failure during service.

The Jerusalem artichoke (Helianthus tuberosus) is a high-yield crop, and a great source of fermentable sugars, which gives the plant the potential to be used as raw material for economical fuel alcohol production. In this article, the authors focus on the technological aspect of the biofuel manufacturing process and its properties. First, the fuel alcohol manufacturing process is described, afterwards assessing its characteristics such as kinematic viscosity, density and octane number. The amount of fuel alcohol obtained from 10 kg of biomass equals to 0.85 L. Afterwards, the mixtures of gasoline and obtained fuel alcohol are prepared and studied. Optimal alcohol and gasoline mixtures are determined to obtain biofuels with octane ratings of 92, 95 and 98. The kinematic viscosity of obtained mixtures does not differ significantly from its values for pure gasoline. The obtained biofuel mixture with 25% alcohol content yielded a decrease of sulfur content by 38%, an increase of vaporized fuel amount by 17.5% at 70 °C and by 10.5% at a temperature of 100 °C, which improves engine startup time and ensures its stable operation in comparison to pure gasoline. The alcohol obtained can be successfully used as a high-octane additive for gasolines.

The free piston engine linear generator (FPELG) is a simple structure engine with only two main parts, i.e., the linear generator and a free piston engine, which has less friction, low emission, high thermal efficiency, and multi-fuel engine. However, the pistons move freely; thus, piston motion control (PMC) is a crucial technical challenge that affects both the performance and stability of FPELG. This review addresses different control techniques and operation parameters of FPELG. Through this review, a new taxonomy method is proposed based on two main groups of control strategies, i.e., the linear-FPE and others-FPE control. The linear-FPE control is classified into the PMC, linear electric machine control, switching control, and combined control. According to this taxonomy, a selection of previous studies was thoroughly analyzed to identify new research directions related to FPELG. The statistical analysis and observations demonstrate that very few studies have used advanced control techniques, e.g., fuzzy logic, neural network, and PID with the genetic algorithm controls, for the FPELG. Some operation parameters require further investigation. Therefore, based on this review, researchers can explore new research directions and select a suitable technique to solve PMC issues of FPELG. This review thus constitutes a useful reference for researchers.

The free piston engine linear generator (FPELG) is a simple structure engine with only two main parts, i.e., the linear generator and a free piston engine, which has less friction, low emission, high thermal efficiency, and multi-fuel engine. However, the pistons move freely; thus, piston motion control (PMC) is a crucial technical challenge that affects both the performance and stability of FPELG. This review addresses different control techniques and operation parameters of FPELG. Through this review, a new taxonomy method is proposed based on two main groups of control strategies, i.e., the linear-FPE and others-FPE control. The linear-FPE control is classified into the PMC, linear electric machine control, switching control, and combined control. According to this taxonomy, a selection of previous studies was thoroughly analyzed to identify new research directions related to FPELG. The statistical analysis and observations demonstrate that very few studies have used advanced control techniques, e.g., fuzzy logic, neural network, and PID with the genetic algorithm controls, for the FPELG. Some operation parameters require further investigation. Therefore, based on this review, researchers can explore new research directions and select a suitable technique to solve PMC issues of FPELG. This review thus constitutes a useful reference for researchers. [ABSTRACT FROM AUTHOR]

The paper presents results of SI engine tests, carried on for different gaseous fuels. The analysis carried out made it possible to define the correlation between fuel composition and engine operating parameters. Tests cover various gaseous mixtures: methane with hydrogen and LPG with DME. The first group, considered as low carbon content fuels, can be characterized by low CO2 emissions. The flammability of hydrogen added in those mixtures realizes the function of combustion process activator and improves the energy conversion. The second group of fuels is constituted by LPG and DME mixtures. DME mixes perfectly with LPG and differently than in the case of other hydrocarbon fuels also consisting of oxygen, which makes the stoichiometric mixture less oxygen demanding. In the case of this fuel, improvement in engine volumetric and overall engine efficiency has been noticed, compared to LPG. During the tests, standard CNG/LPG feeding systems have been used, which underlines the utility value of the research.

Each combustion chamber of the Fourier engine is open to multiple cylinders, which have pistons connected to crankshafts that rotate at different rates. The displacements of the individual cylinders and the relative phases of the pistons are selected according to a Fourier approximation of a prescribed time dependence of the volume of the combustion chamber. The parameters are selected so that the duration of the intake and ignition strokes is greater than the duration of the compression and exhaust strokes. As the speed of an engine increases, the power curve initially climbs approximately linearly, but it levels off as intake and ignition become less efficient at high rpm. By increasing the duration of these strokes relative to the duration of the other strokes, it may be possible to allow the power curve to climb higher before leveling off.

Providing high ignition energies to low reactivity (hard-to-ignite) fuels in premixed combustion modes is a challenging task. This is especially true if diluted combustion and high compression ratios are applied which are desirable for achieving high efficiency levels. One promising technology is to decouple the ignition process from the conditions in the main chamber using a prechamber, which is able to ignite the charge in the engine's main combustion chamber using turbulent jets. In this study, experimental results of a prechamber-equipped four-cylinder engine with 2 L displacement are discussed. The engine is designed to provide high efficiency using natural gas as a fuel. The prechamber is able to be fueled externally (called active prechamber mode), e.g. the air–fuel equivalence ratio λ can be decoupled from the λ in the main combustion chamber. Besides of pure methane operation, the engine is operated with the addition of 22.5 mol% (3.5 mass%, 8.0 energy%) hydrogen to methane. The results show that it is beneficial to use auxiliary fueling of the prechamber in pure methane operation mode in order to achieve highest possible efficiency at low NO x levels at λ of around 1.7. When adding hydrogen, λ of around 1.7 still provides highest efficiency but auxiliary fueling of the prechamber is not necessary any more to enable fast and robust combustion. Compared to the active prechamber operation with methane, the 3.5 mass% (8.0 energy%) addition of hydrogen is able to reduce the engine's fuel energy demand by 1.3–3.3% in relevant engine operating points, which leads to tailpipe CO 2 reductions of 9.2–11%. Additionally, hydrogen addition is able to disproportionately lower the engine's unburned hydrocarbon (HC) emissions: The addition of 3.5 mass% hydrogen lowers HC mass emissions by impressive 30–40%. Simultaneously, at the lean conditions considered, CO and NO x emissions are lowered by around 20%. • Hydrogen accelerates combustion and extends the lean limit. • Hydrogen addition reduces tailpipe CO 2 emissions by substituting carbon by hydrogen. • The energy conversion efficiency increases by hydrogen addition. • Small amounts of hydrogen massively reduce hydrocarbon emissions. • Hydrogen addition avoids the need of prechamber fueling for hard-to-ignite mixtures. [ABSTRACT FROM AUTHOR]

This article reviews split-cycle internal combustion engine designs. The review includes historical work, assessment of prototypes and discussion of the most recent designs. There has been an abundance of split-cycle engine designs proposed since the first in 1872. Despite this, very few prototypes exist, and no split-cycle engines are reported to be in series production. The few split-cycle prototypes that have been developed have faced practical challenges contributing to limited performance. These challenges include air flow restrictions into the expansion cylinder, late combustion, thermal management issues, and mechanical challenges with the crossover valve actuation mechanism. The main promoted advantage of split-cycle engines is the increased thermal efficiency compared to conventional internal combustion engines. However, an efficiency improvement has not thus far been demonstrated in published test data. The thermodynamic studies reviewed suggest that split-cycle engines should be more efficient than conventional four-stroke engines. Reasons why increased thermal efficiency is not realised in practice could be due to practical compromises, or due to inherent architectural split-cycle engine design limitations. It was found that the number of split-cycle engine patents has increased significantly over recent years, suggesting an increased commercial interest in the concept since the possibility of increased efficiency becomes more desirable and might outweigh the drawbacks of practical challenges. [ABSTRACT FROM AUTHOR]

An improved thermodynamic open Dual cycle is proposed to simulate the working of internal combustion engines. It covers both spark ignition and Diesel types through a sequential heat release. This study proposes a procedure that includes (i) the composition change caused by internal combustion, (ii) the temperature excursions, (iii) the combustion efficiency, (iv) heat and pressure losses, and (v) the intake valve timing, following well-established methodologies. The result leads to simple analytical expressions, valid for portable models, optimization studies, engine transformations, and teaching. The proposed simplified model also provides the working gas properties and the amount of trapped mass in the cylinder resulting from the exhaust and intake processes. This allows us to yield explicit equations for cycle work and efficiency, as well as exhaust temperature for turbocharging. The model covers Atkinson and Miller cycles as particular cases and can include irreversibilities in compression, expansion, intake, and exhaust. Results are consistent with the real influence of the fuel-air ratio, overcoming limitations of standard air cycles without the complex calculation of fuel-air cycles. It includes Exhaust Gas Recirculation, EGR, external irreversibilities, and contemporary high-efficiency and low-polluting technologies. Correlations for heat ratio γ are given, including renewable fuels.

The paper presents results of SI engine tests, carried on for different gaseous fuels. The analysis carried out made it possible to define the correlation between fuel composition and engine operating parameters. Tests cover various gaseous mixtures: methane with hydrogen and LPG with DME. The first group, considered as low carbon content fuels, can be characterized by low CO2 emissions. The flammability of hydrogen added in those mixtures realizes the function of combustion process activator and improves the energy conversion. The second group of fuels is constituted by LPG and DME mixtures. DME mixes perfectly with LPG and differently than in the case of other hydrocarbon fuels also consisting of oxygen, which makes the stoichiometric mixture less oxygen demanding. In the case of this fuel, improvement in engine volumetric and overall engine efficiency has been noticed, compared to LPG. During the tests, standard CNG/LPG feeding systems have been used, which underlines the utility value of the research. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrotreating of bio-crude improved the distillates recovery and properties. • Hydrotreating of bio-crude led to a higher share of bioblendstock in the final blend. • Distillation enhanced the blending properties of the raw and hydrotreated bio-crude. • A 10 wt% share of bioblend to the reference diesel closely followed EN590. • The optimized blends showed on-par emission results compared to the reference diesel. Hydrothermal liquefaction (HTL) bio-crude is known as a potential alternative to conventional fossil fuels in the existing infrastructure. Although HTL has enormous potential as a process for renewable fuel production, developing economically viable HTL-based value-chains has encountered extensive challenges owing to the contaminants and the complex matrix it possesses. Therefore, devising efficient downstream processing and blending strategies is of high importance. This study evaluates different bio-crude refining scenarios; namely 1) pre-stabilization using partial hydrotreating, 2) fractionation through vacuum distillation and 3) the integration of the former processes, in producing a compliant HTL-derived road diesel blendstock. The combination of the distillation fractions is optimized through a multi-objective optimization method minimizing the deviation from the road diesel standard specifications. The optimized blend fuels are combusted in an optical accessible compression-ignited chamber (OACIC) to assess the exhaust emissions. Partial hydrotreating successfully improves the distillation recovery from 22.7 wt% (raw bio-crude) to 55.6 wt% along with a significant improvement in the physicochemical properties. The hydrotreated bio-crude distillate mixture is an adequate diesel blendstock that complies with the standard specification by at least 5 wt% contribution to the finished fuel. The results also show that with a slight improvement in the desulphurization of bio-crude, the bio-blendstock share can increase up to 10 wt%. With the comparable GHG emission profile to the reference diesel, the hydrotreated bio-crude distillate mixture heralds a promising green blendstock that can significantly contribute to meeting the current road transport diesel fuel demand. [ABSTRACT FROM AUTHOR]

The engine is the heart of any hardware which may relate to various applications like Vehicles, Railway, etc. The rail application is the application where the engine will work as a main unit of the system. Cummins India Limited is the company which provides the diesel engine to various applications. The diesel engine to rail application is one of the new trends in Cummins. The modification to the railway engine and their system may give better facility to the engine. The engine is of a various type depending on their fuel consumption. The engine is classified into two types depending on which fuel is used for the engine, they are gasoline and diesel engine. The engine is further classified into two types depending on the combustion taking place in the engine, they are internal and external combustion engine. In the rail application, the diesel engine is selected because it has some advantages over the gasoline engine, where the diesel engine falls under the internal combustion type of engine. The rail application with the diesel engine further provided with the engine safety parameters will give the better rail application system. The existing system for the railway has some drawbacks which are explained in this paper and what provision necessary to be taken to provide the best system for the rail application is explained here. The existing system for the rail application consists of the display panel, the drawbacks of the existing panel, and need for the new digital display panel is also explain here. [ABSTRACT FROM AUTHOR]