Engine Combustion System Research Articles

Analysis of the combustion engine exhaust system structure in aspect of shaping acoustic energy

The flow of exhaust gases is the source of many physical processes, including thermal, acoustic, mechanical and chemical phenomena with high dynamics of changes. The study analyzes the impact of the entire structure of the exhaust system on the formation of acoustic energy, determining the transmission loss characteristics of its individual components and the entire system. On the example of a structure based on a proprietary solution of an adjustable reactive muffler, the possibilities of shaping the flow of acoustic waves in the process of designing and selecting exhaust systems for internal combustion engines were determined. The study was carried out with the use of the CFD method and a specialized package for advanced simulations AVL AST.

CFD Investigation of an Innovative Additive Manufactured POCS Substrate as Electrical Heated Solution for After-Treatment Systems

In the last decade, additive manufacturing (AM) techniques have been progressively applied to the manufacturing of many mechanical components. Compared to traditional techniques, this technology is characterized by disruptive potential in terms of the complexity of the objects that can be produced. This opens new frontiers in terms of design flexibility, making it possible to create new components with optimized performances in terms of mechanical properties and weight. In this work, the focus is on a specific field of application: the development of novel porous media structures which can be the basis of advanced after-treatment systems for internal combustion engines. In particular, the possibility to design periodic open cellular structures (POCSs) that can be applied as catalytic substrates opens new perspectives in terms of flexibility and integrated functionalities. The present study investigates an innovative solution where the catalytic substrates are located in the pipes of the exhaust manifolds of a high-performance engine. A preliminary characterization of the pressure drop induced by the POCS structure is carried out, with a particular focus on the impact of the backpressure on the engine performances. Moreover, each POCS integrates an electrical circuit which is used to promote the heating of the device, with beneficial effects on the light-off of the catalytic reactions. An advanced CFD model is applied to evaluate the potential of the solution, comparing the pollutant conversion with that of the baseline configuration equipped with a standard after-treatment system solution.

РАСЧЕТ БАРИЧЕСКИХ КОЭФФИЦИЕНТОВ ТЕПЛОПРОВОДНОСТИ СМЕШАННЫХ РАСТВОРОВ ЭЛЕКТРОЛИТОВ

In the paper presents the calculated optimal values of the baric thermal conductivity coefficients corresponding
 to the minimum of the quadratic functional in comparison with the baric dependences of aqueous solutions of
 ethylene glycol and electrolytes in the cooling systems of marine internal combustion engines. For the pressure
 dependences of electrolyte solutions, an equation was obtained that makes it possible to calculate the thermal
 conductivity of mixed solutions at any pressure with an average error of 1.2%. Scientific interest lies in the
 study of the nature of the dependence of the baric coefficients of thermal conductivity of mixed electrolyte
 solutions on temperature when using the latter along with ethylene glycol coolants

Review on Plasma-Assisted Ignition Systems for Internal Combustion Engine Application

Due to the depletion of conventional petroleum-based fuels and increasing environmental concerns, industries have been developing new combustion technologies with acceptable cost ranges and minimum system modifications for consumers. Among many approaches, the utilization of plasma ignition systems is considered as a promising pathway to achieve greener transportation while maintaining conventional internal combustion engine systems. Plasma contains highly reactive radicals, and those have a great potential of enhancing chemical reactions that are beneficial for reducing carbon emissions. The primary objective of this paper is to provide an overview of currently available plasma-assisted combustion systems including recent achievements in research and development, and technical challenges for successfully implementing a new ignition system. This review will introduce various plasma-assisted combustion approaches from worldwide projects, covering non-thermal and thermal plasma systems in internal combustion engines.

Thermodynamic analysis of exhaust heat recovery of marine ice using organic rankine cycle

The use of organic Rankine cycle power systems for waste heat recovery on marine internal combustion engines can help to mitigate the GHG and reduce the fuel consumption of the marine engine. In this paper, the internal combustion engine combined with an organic Rankine cycle system was developed to analyze the performance of waste heat recovery from the exhaust gas of a heavy-duty marine Diesel engine via five selected working fluids with low global warming potential and ozone depletion potential. The net output power and thermal efficiency for each of the selected working fluids were obtained. Results indicate that the working fluids of butane have the best performance among the selected working fluids with the power efficiency of the organic Rankine cycle subsystem of 12.27% under the power load of 100%. For the overall proposed system, the maximum net power output is 1048 kW and the power efficiency is 36.47%. Besides, the total thermal efficiency of the proposed system was 67.94% when considering the recovered waste energy from jacket water.

A review on autonomous electric vehicle communication networks-progress, methods and challenges

Electric vehicles have gained significance owing to its unavoidable supporting factors including environmental impacts and climate features. It has been noticed over last few decades that the increased number of manufacturers have focused on electric propulsion-based technology either pure electric or hybrid form with the support of electric vehicles in the automotive market. The adoption of these electric vehicle has obviously increased its competitive nature while compared to traditional internal combustion engine system. Moreover, the electric vehicles (EVs) possess substantial potential, not only in minimizing carbon emission but also in assisting required energy storage to contribute to the distributed renewable generation. There exist several increases in electric vehicle usage, but their level of massive adoption and existence by automotive consumers is connected with its delivered performance. One such important feature is the autonomous electric vehicle communication networks. This research provides a comprehensive review on overview of the electric vehicles and will discuss various existing works on autonomous driving vehicles. The paper compares existing communication networks and nuances associated in the context of an autonomous electric vehicle. Also, it critiques the existing technology and provides suggestive future work in the field to make communication networks resilient. An extensive review makes it possible to ascertain future research directions in the EV research field, which would result in massive future and instantaneous EV perception in the automotive market.

Macroscopic spray characteristics and internal structure studies of natural gas injection

The macroscopic spray characteristics and internal structure of a highly expanded compressed natural gas (Methane; CH4) spray were experimentally and numerically investigated. The spray jet characteristics were analyzed under various pressure ratios (PR), defined as the ratio of the methane injection pressure to the ambient pressure. The spray characteristics and shockwave structures were investigated using Schlieren imaging. The novelty originates from comparing the methane spray development and shockwave parameters under low PR (4 < PR < 9) conditions. The investigation included an evaluation of the effect of choking phenomena on gas flow at different PRs by changing the methane injection pressure. The results showed that a high injection pressure did not improve the spray tip penetration but increased the choking phenomenon in methane flow in the near-field region. This phenomenon is a key factor that strongly influences the shockwave structure and leads to 3.5% longer injection duration and at least 13% increase in the spray volume and area before entering the fully developed region of the Mach disk. With respect to the Mach disk parameters, a PR change from 6 to 9 enhanced the Mack disk height by at least 13.5% and its width by at least 29%. Increasing the Mach disk width with PR increased the methane near-field angle of the spray by at least 29%, triple-point angle by at least 29%, and spray width at the triple point by at least 29% because of the larger radial gas spray development. Overall, the comparison of the macroscopic spray characteristics and Mach disk parameters showed that the macroscopic spray parameters were almost similar despite the changes in the PRs. In contrast, the Mach disk parameters (height, width, and triple point angle) and variations in the methane spray field were larger than those in the macroscopic spray parameters. In addition, the simulation results were used to analyze the energy conservation and transfer conversion efficiencies of the gaseous injection system. The same increase in PR led to greater energy transfer and conversion efficiencies by 0.05% and 6.7%, respectively, which adversely affects charge mixing in the intake manifold. Strong air turbulence is required to enhance the charge-mixing mechanism and achieve a homogeneous fuel-air mixture. Therefore, the choking phenomenon requires more attention when implementing gaseous injection systems for internal combustion engines.

Combustion Modeling Approach for the Optimization of a Temperature Controlled Reactivity Compression Ignition Engine Fueled with Iso-Octane

In this study, an innovative Low Temperature Combustion (LTC) system named Temperature Controlled Reactivity Compression Ignition (TCRCI) is presented, and a numerical optimization of the hardware and the operating parameters is proposed. The studied combustion system aims to reduce the complexity of the Reaction Controlled Compression Ignition engine (RCCI), replacing the direct injection of high reactivity fuel with a heated injection of low reactivity fuel. The combustion system at the actual state of development is presented, and its characteristics are discussed. Hence, it is clear that the performances are highly limited by the actual diesel-derived hardware, and a dedicated model must be designed to progress in the development of this technology. A Computational Fluid Dynamics (CFD) model suitable for the simulation of this type of combustion is proposed, and it is validated with the available experimental operating conditions. The Particle Swarm Optimization (PSO) algorithm was integrated with the Computational Fluid Dynamic (CFD) software to optimize the engine combustion system by means of computational simulation. The operating condition considered has a relatively high load with a fixed fuel mass and compression ratio. The parameters to optimize are the piston bowl geometry, injection parameters and the boosting pressure. The achieved system configuration is characterized by a wider piston bowl and injection angle, and it is able to increase the net efficiency of 3% and to significantly reduce CO emissions from 0.407 to 0.136 mg.

Potential applications of thermoelectric generators (TEGs) in various waste heat recovery systems

Nowadays the World faces critical issues, such as increasing power costs, environmental impacts of fossil fuel, and global warming. In this respect, scientists are trying to improve the efficiency of the energy harvesting. The enhancement of power generation sectors is focused on the waste heat recovery systems based on thermoelectric generators (TEGs) that have demonstrated the capacity to transfer thermal energy directly into electric energy via the Seebeck effect. TEG uses the available waste heat sources in different applications to produce power, thus it considered as an eco-friendly power source. In the present study, the integration of thermoelectric systems with other technologies for green power production is introduced. This work introduces a background about the common materials used in the fabrication of the TEG. Furthermore, the application of the TEG to harvest waste heat from different sources, i.e., fuel cells, heat exchangers, photovoltaics, internal combustion engine, electric vehicles, and hybrid waste heat recovery systems have been summarized. The characteristics of thermoelectric generators are discussed, considering the different operating and design parameters. Finally, the barriers and challenges facing the applications of the thermoelectric generators for waste heat recovery are also discussed.

Development and experimental assessment of a Low Speed Sliding Rotary Vane Pump for heavy duty engine cooling systems

Sliding Rotary Vane Pumps (SVRPs) are real candidates to replace the conventional centrifugal machines for engine cooling systems. Differently from the centrifugal pumps, SVRP performances are theoretically independent from the operating conditions, preventing in this way a lower efficiency when the machines work far from the design point. To achieve these benefits, however, the SVRP should be properly designed especially in those applications characterized by high flow rate of coolant delivered as in the case of heavy-duty engine cooling systems. A common design approach is the increase of flow rates pushing SVRPs to operate with high speeds of revolution, aiming to minimize the pump dimensions for space and weight constraints on board. Nevertheless, friction power lost is recognized as the main limit of this positive displacement technology and grows with revolution speed. Hence, SVRPs employed in cooling systems of heavy-duty internal combustion engines (ICEs) are particularly critical from this point of view.Considering this aspect, a novel design method is developed based on the reduction of operating revolution speed, increasing the chambers volume, but through a refined optimization of the volumetric, indicated and mechanical efficiencies reached by a model-based approach.Chamber volume enhancement has been performed thanks to a slight increase of the pump radial dimension (+3%) which produces a significant growth (+27 %) of the chamber volume without a significant effect on the overall pump size. This ensures the reduction of revolution speed satisfying the space and weight requirements.Volumetric and indicated efficiencies have been improved adopting a dual intake and exhaust port solution. Mechanical efficiency was investigated and improved via the use of lighter blades (graphite). Attention has been paid to the negative feedback on volumetric efficiency produced by the leakage increase among adjacent chambers.Therefore, a Low-Speed LS SVRP was designed for a Natural Gas 13L engine (IVECO CURSOR 13). A prototype was built and tested for a revolution speed ranging between 250 RPM and 2000 RPM and a pressure rise and flow rate interval equal respectively to 0.05–2 bar and 50–500 L/min. A novel aspect of the experimental campaign is the assessment of pressure variation inside the chambers which provides fundamental information about the fluid-dynamic behavior of the machine. Measurements allowed to characterize volumetric, indicated and mechanical performances. Moreover, data were used to validate a comprehensive model-based platform which was the tool for further design refinement and processes understanding.The experimental analysis shows efficiency values around 60%, well beyond what was achievable with centrifugal pump with an efficiency which keeps significantly higher at off design conditions with respect to a centrifugal pump. Moreover, the LS SVRP was experimentally compared with a SVRP designed with a conventional method observing an efficiency improvement up to 25 %.

Maximizing Lubricant Life for Internal Combustion Engines

Although the lubrication systems for internal combustion engines have been designed to prevent engine wear and friction, their configuration does not contemplate the maximum use of each load of lubricant; because of this limitation, lubricant consumption is currently an environmental and economic problem. In this work, the performance of lubrication systems to form the tribological film that prevents wear is simulated and optimized, through the mass balance of the lubricant precursors contained in the oil and the implementation of optimal control techniques. Optimization results indicate that regulating the flow of lubricant passing through the engine prevents excessive degradation of lubricant precursors, maximizing the life of each lube oil charge, giving the possibility to increase the sustainability of internal combustion engines.

Miscibility of Aviation Turbine Engine Fuels Containing Various Synthetic Components

This article reviews a study of the impact of synthetic biocomponents on the operational properties of aviation turbine engine fuels. The objective of the research was to simulate the functioning of aircraft fuel supply systems during the popularization of synthetic components and to provide a preliminary study of the impact of particles of various synthetic components on processes within aviation turbine engine fuel systems—particularly the aviation turbine engine combustion system. The authors produced Jet A-1 fuel blends with two selected synthetic components A and B, accepted as per the ASTM D4054 procedure. The concentrations of each of the components were selected to simulate fuel compositions in an aircraft tank that could result from supplying fuel with different synthetic components. Such blends were studied using selected laboratory tests, lubricity using the BOCLE rig and an engine test using the MiniJetRig stand. The parameters of the following power functions were adopted as criteria for a comparison of the combustion process involving fuels of various chemical structure: CO = amfn and (T3max − T2)/(T3min − T2) = a11mfn1, where CO—carbon monoxide content in exhaust gas; T3max—maximum combustion chamber temperature; T3min—minimum combustion chamber temperature; T2—temperature upstream the combustion chamber; mf—fuel mass flow rate. The test results for blends containing both synthetic components A and B were compared with change trends of similar parameters in fuels containing single synthetic components. Hard-to-predict and hard-to-define trend line deviations for the blends of both components A and B were observed. The obtained research results indicated a need to study the miscibility of fuels containing various synthetic components and to improve miscibility research methodologies.

Cleaning the lubricant from mechanical impurities using a magnet-cotton filter

This article examines the issues of contamination by mechanical impurities flowing from the environment into the oil of an internal combustion engine or tractor hydraulic system, the intensity of wear of pairs of rubbing surfaces, methods for reducing abrasive wear, destruction of the oil film layer, dispersed component, the ingress of abrasive particles (formed due to friction between pairs of rubbing parts) into the oil sump and hydraulic system tractors. Filtration of internal combustion engine oil or tractor hydraulic system, description of magnetic cotton filter and design features of this filter. After passing through magnetically cotton filtration, the purified oil is pumped to the rubbing surfaces to reduce friction, cool the rubbing surfaces from the heat generated and wash away abrasive particles from the rubbing surfaces.

Water pump filter removal and filter performance study at heavy commercial vehicle engine

Cooling systems are one of the essential systems for internal combustion engines. They prevent damage to engine parts and extend the engine’s life by removing the high heat generated by the combustion from the engine. These systems vary depending on the engine’s volume, combustion pressure, coolant flow, and types and may differ in light commercial and heavy commercial vehicles. These differences are generally observed in the water pump used, type of refrigerant, filter systems, and pump control mechanisms. The most apparent differences are in the water pump and filter systems. Light commercial vehicles do not have a filtration system, while most of the heavy commercial vehicles have a filtration system. There are many studies in the literature focusing on the performance and durability of the filter systems.In this study, the necessity of the filter system in the cooling systems of heavy commercial vehicles, system filtration performance, and whether it is possible to work without a filter were investigated. A water pump performance test setup was used to simulate the real engine condition. The test was performed at 110°C coolant temperature, 1 barg input pressure, and with 53.195gr contamination. Results of the study showed that removing the filter from the coolant system after the first service shortens the life of the water pump.

An Experimental Study of the TEG Performance using Cooling Systems of Waterblock and Heatsink-Fan

Two third of the total energy in the internal combustion engine (ICE) system is lost and turns as waste heat through the exhaust system and coolant circulations. Therefore, it is necessary to have a technology that is able to convert waste heat from ICE into electrical energy using thermal electric generator (TEG). To have the best thermoelectric generator (TEG) performance in terms of higher electricity generation, the temperature on the hot surface should be higher, and the temperature on the cold surface should be as low as feasible. The goal of the study was to study how differences in TEG cooling systems affected the overall performance. Water block and heatsink-fan are two different types of cooling systems that have been used in this experiment. The water flow rate in water block cooling systems varies between 200, 300, 400, 500, and 600 l/h. The TEG module was heated with gas-fired lighters. Arduino-based data loggers were used to record hot and cold temperatures on the TEG surface. A USB multimeter is used to measure TEG performance as electrical voltage. The results showed that 300 l/h was the best water flow rate for TEG cooling. When using a water block cooling system instead of a heat sink, the electrical voltage generated by the TEG module is 12 percent higher. This study found that a cooling system with water blocks is superior to heatsink-fan.

Study on Engine Performance and Combustion System Optimization of a Poppet-Valve Two-Stroke Diesel Engine

Two-stroke engines have higher power density than traditional four-stroke engines, and therefore are suitable for engine downsizing. In this work, a four-stroke single-cylinder diesel engine is modified for two-stroke operation, and the combustion system is designed and optimized using a 3D simulation. Three different combustion chamber profiles and injection spray angles are compared to determine an optimized combustion system. The engine test results show that the two-stroke engine equipped with the newly designed combustion system is able to achieve the same effective power output at a much lower speed than the original four-stroke engine, as well as obtain a better indicated thermal efficiency. This indicates that the poppet-valve two-stroke engine could be an effective technical approach for engine downsizing.

LES-Predicted Flow Patterning in a Newly-Designed Reference Test Sample with Relevance to IC Engine-Related Cooling Channels

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;A test sample configuration with a circular cross-section has been conceptualized to reproduce all geometrically relevant flow-guided elements - straight segments, deflections, bifurcations, impingement regions, confluence - as they can also be found in the cooling systems of realistic Internal Combustion (IC) engines. This newly-designed reference test sample is termed as Water Spider Geometry (WSG), with the shape inspired by the flow guidance around an IC engine cylinder head. Computational investigations are carried out within the framework of a BMWi (German Federal Ministry for Economic Affairs and Energy) project by applying a well-resolved, highly comprehensive Large Eddy Simulation aiming at providing a meaningful assessment of the isothermal flow topology within the WSG. The basis forms a fully-hexahedral, block-structured grid arrangement comprising 290 million cells with the results considered to be a reference solution for further investigations.&lt;/div&gt;&lt;/div&gt;

Simulation of particulate matter structure detachment from surfaces of wall-flow filters applying lattice Boltzmann methods

Wall-flow particulate filters are used for particulate matter removal from exhaust in aftertreatment systems of combustion engines. Inside these filters, the gas flow passes through a porous wall between oppositely arranged inlet and outlet channels. Due to continuously introduced solid material, the filters have to be regenerated resulting in a breakup of continuous layers deposited on the walls into individual fragments. Those can re-arrange and impact operational filter performance significantly.This process is governed by the interaction of hydrodynamic and adhesive forces, which can only be accurately modelled by taking the surfaces of individual layer fragments into account. With surface resolved simulations, those forces can be evaluated and detailed investigations of detachment and rearrangement processes can be performed.The present work, therefore, presents a lattice Boltzmann approach for the simulation of particulate matter structure detachment capable of capturing the time dependent evolution of the flow field during the filter’s regeneration. First, a numerical model of a single wall-flow filter channel is presented and its validity for the particle-free case is substantiated by showing super-linear grid convergence and good agreement with a reference solution. Then, the model’s capability is shown by applying it to the transient simulation of the rearrangement process.

Toward the European 2030 CO2 target with gasoline compression ignition technology and 48 V mild electric hybrid

The pressure to reduce CO2 and criteria pollutants of internal combustion engines (ICE) powered vehicles is higher than ever. The existing gasoline and diesel engine vehicles face a critical challenge to adjust to these stringent demands. By combining a clean fuel like gasoline with a high efficiency thermodynamic cycle (compression ignition), it is possible to create a powertrain that is clean both globally and locally thus breaking the historical trade-off between decreasing CO2 and reducing criteria pollutants. Recent works have demonstrated the potential of higher reactivity gasoline (HRG) fuels to reduce NOX and particulate emissions simultaneously when used in compression ignition (CI) engines. After performing the engine calibration using Design of Experiment (DoE), tests on a roller bench were conducted on a vehicle adapted to be operated with HRG. The results show 7% CO2 reduction using HRG fuel compared to the baseline diesel vehicle while 17% of CO2 benefit compared to the best in class SI car of equivalent size and power. Furthermore, vehicle simulations were used to assess the potential of the GCI vehicle technology when combined with a hybrid electric architecture. From the HEV simulation study, the 2030 CO2 target was reached by using a 48 V 1 kWh battery, P2 architecture, and recalibration the internal combustion engine and after-treatment system (ATS) while fulfilling the expected new EU’s pollutant emission standards.

Modeling of Diesel Engine Fuel Systems Reliability When Operating on Biofuels

One of the main trends in the development of modern engine building is the use of biodiesel fuel, which can lead to a decrease in the reliability of engines that are not adapted to it. However, at present there is no general method for determining the reliability of fuel systems of internal combustion engines. In this paper, a reliability model of engine fuel systems when operating on biofuel has been developed. Comprehensive indicators for assessing the reliability of diesel engine fuel systems are the coefficient of readiness and technical use. The availability factor of the fuel system when operating on biodiesel fuel without the replacement of structural materials was 0.66, while with the replacement it was 0.71, and the coefficient of technical utilization without replacement of materials was 0.36, and with the replacement of 0.4. Recommendations are given to improve the reliability of the engine fuel system components. The resulting model allows for complex comparisons of the effectiveness of various ways to improve the reliability of engines running on biodiesel fuel.