Efficiency Of Internal Combustion Engines Research Articles

Constructing a Skeletal Iso-Propanol–Butanol–Ethanol (IBE)–Diesel Mechanism Using the Decoupling Method

In recent years, biofuels have gained considerable prominence in response to growing concerns about resource scarcity and environmental pollution. Previous investigations have revealed that the appropriate blending of iso-propanol–butanol–ethanol (IBE) into diesel significantly improves both the c combustion efficiency and emission performance of internal combustion engines (ICEs). However, the combustion mechanism of IBE–diesel for the numerical studies of engines has not reached maturity. In this study, a skeletal IBE–diesel multi-component mechanism, comprising 157 species and 603 reactions, was constructed using the decoupling method. It was formulated by amalgamating the reduced fuel-related sub-mechanisms derived from diesel surrogates (n-dodecane, iso-cetane, iso-octane, toluene, and decalin) and n-butanol, along with the detailed core sub-mechanisms of C1, C2, C3, CO, and H2. The constructed mechanism is capable of better matching the physical and chemical properties of actual diesel fuel. Extensive validation, including ignition delay, laminar flame speed, a premixed flame species profile, and engine experimental data, confirms the reliability of the mechanism in engine numerical studies. Subsequent investigations reveal that as the IBE blend ratio and EGR rate increase, the ignition delay exhibits an increase, while the combustion duration experiences a decrease. Blending IBE into diesel, along with a specific EGR rate, proves effective in simultaneously reducing NOx and soot emissions.

Making sense of life cycle assessment results of electrified vehicles

Battery electric vehicles and plug-in hybrid electric vehicles can have life-cycle carbon dioxide emissions that can be close, within 5 % of each other, or very different depending on the efficiencies of the powertrain, relative contributions of battery and combustion engine to the traction power, and source of electricity. Life cycle assessments can provide insight into the variability in carbon dioxide emissions, but they are time consuming. In this work a simplified model that can explain the carbon dioxide emissions during the well-to-wheels portion of the life cycle is developed. The robustness of the simplified model is evaluated by varying parameters and comparing its results with those from the life cycle assessment. Assumptions must be made to conduct the assessment. The assumptions include the efficiencies of the internal combustion engine, the battery, the drivetrain, and regenerative braking, and the relative contribution of the battery to traction power in the plug-in hybrid electric vehicle. Renewable and non-renewable sources of generating electricity are considered. It is concluded that a plug-in hybrid electric vehicle with the same parameters as the battery electric vehicle can potentially be lower emitting only when the emissions factor of the electricity generation and the internal combustion engine efficiency are high. For low carbon intensity electricity generation, the plug-in vehicle emits more carbon dioxide than the battery electric vehicle for the range of internal combustion engine efficiencies considered.

Stress mitigation of a thermal engine head block using the bioinspired BGM-FEM method

Structural optimization plays a pivotal role in the design and development of engine heads, as it directly affects the performance, efficiency, and durability of internal combustion engines. In this paper, we propose a novel approach for the thermo-structural optimization of the internal surfaces of the engine heads, using the Biological Growth Method (BGM). The BGM is a bio-inspired technique that mimics the growth patterns observed in some biological organisms, able to achieve superior structural efficiency thus generating optimal designs. The effectiveness of the BGM methodology, coupled with mesh morphing techniques based on Radial Basis Functions (RBF), is in this work demonstrated for several districts, effectively reducing material usage and enhancing structural performance.

The effects of ammonia addition on the emission and performance characteristics of a diesel engine with variable compression ratio and injection timing

Ammonia, future of the carbonless marine fuel, presents significant potential in achieving zero-emission targets within maritime transportation. In this context, this study explores the use of an ammonia/diesel fuel mixture in a diesel engine, employing both experimental and numerical methods. We focus on the impact of injection timing and compression ratio to optimize the engine while using ammonia/diesel mixture in terms of both engine performance and exhaust emissions. The results show a decrease in engine power with an increasing content of ammonia, reaching the lowest power of 4.53 kW at 60% ammonia content. On the other hand, the increase in compression ratio generally enhances engine power. Thermal efficiency shows an increase up to 40% ammonia content, followed by a decline. CO2 emissions significantly reduce with an increase in ammonia content, reaching the lowest level, especially at 60% ammonia content. NO emissions rise with increasing ammonia content up to 40%. Furthermore, increasing the compression ratio reduces CO2 emissions and contributes to an increase in NOx emissions. These findings have assessed the potential usage of ammonia-diesel fuel mixture with regards to environmental impacts and energy efficiency in internal combustion engines.

On convection vive in mixing-controlled combustion with thermal barrier coatings

Thermal barrier coatings (TBCs) could improve the efficiency of internal combustion engines by reducing heat losses. TBC modeling has demonstrated efficiency gains at all loads in compression ignition, including in gasoline compression ignition (GCI). However, after GCI testing of 13 coated pistons of various materials, thicknesses, and surface preparations in this work, a clear trend was observed: TBCs result in an efficiency gain at 6 bar IMEPn (low load) and an efficiency penalty at 15 bar IMEPn (high load). This can be explained by “convective vive”, which was originally presented by Woschni for engines with TBCs. Convection vive refers to a reduction in the quench distance of a reacting flame when the quenching surface temperature is elevated, resulting in an increased heat transfer coefficient and heat transfer rate despite the lower temperature difference between the gas and the wall. Although this work is unable to provide direct experimental evidence for convection vive, several experiments were performed to rule out alternate theories including differences in heat release rate, radiation heat transfer, combustion chamber deposits, and surface catalytic effects. Experiments also showed that at 6 bar IMEPn, injection pressure did not impact the performance of the TBC compared to the metal baseline, but at 15 bar IMEPn, the efficiency penalty increased with rail pressure. These results provide indirect evidence of convection vive: as the surface temperature of the TBC increases with load past a threshold, the quench distance decreases to the point where exothermic reactions can occur in the boundary layer, which raises the convective heat transfer coefficient. This implies that in mixing controlled combustion systems, the TBC should not be present on combustion chamber surfaces that experience high fuel-wall interaction during combustion.

Efficiency Evaluation of Using Water-Fuel Emulsion as Fuel for Automobiles

Road transport is the main consumer of petroleum fuel as well as a source of toxic substances. Therefore, reducing fuel consumption and emissions of harmful substances in road transport is one of the most important problems facing modern engine construction. One of the ways to solve this problem is through the use of mixed fuels, including water-fuel emulsions. Water-fuel emulsion is a promising alternative fuel that could fulfill such requests in that it can improve the combustion efficiency of internal combustion engines and reduce harmful exhaust emissions, especially nitrogen oxide (NOx) and particulate matter (PM). Up to now, there have been many studies on water-fuel emulsions, especially on performance, emissions and micro-explosion phenomena. Using water-fuel emulsion as fuel for ships worldwide was studied and applied to the 80-ies of the last century, but using it for automobiles is still limited by the emulsion stability and economic difficulties to calibrate engine parameters for a new fuel. This article provides an overview of the mechanism and performance operating cycle of internal combustion engines using water-fuel emulsions and the efficiency, economy, and environmental friendliness of this fuel type for automobiles. Hence, conclusions are drawn about the possibility and effectiveness of using emulsions as fuel for automobiles, especially under conditions in Vietnam.

Swirl-induced motion prediction with physics-guided machine learning utilizing spatiotemporal flow field structure

Purpose Higher energy conversion efficiency of internal combustion engine can be achieved with optimal control of unsteady in-cylinder flow fields inside a direct-injection (DI) engine. However, it remains a daunting task to predict the nonlinear and transient in-cylinder flow motion because they are highly complex which change both in space and time. Recently, machine learning methods have demonstrated great promises to infer relatively simple temporal flow field development. This paper aims to feature a physics-guided machine learning approach to realize high accuracy and generalization prediction for complex swirl-induced flow field motions. Design/methodology/approach To achieve high-fidelity time-series prediction of unsteady engine flow fields, this work features an automated machine learning framework with the following objectives: (1) The spatiotemporal physical constraint of the flow field structure is transferred to machine learning structure. (2) The ML inputs and targets are efficiently designed that ensure high model convergence with limited sets of experiments. (3) The prediction results are optimized by ensemble learning mechanism within the automated machine learning framework. Findings The proposed data-driven framework is proven effective in different time periods and different extent of unsteadiness of the flow dynamics, and the predicted flow fields are highly similar to the target field under various complex flow patterns. Among the described framework designs, the utilization of spatial flow field structure is the featured improvement to the time-series flow field prediction process. Originality/value The proposed flow field prediction framework could be generalized to different crank angle periods, cycles and swirl ratio conditions, which could greatly promote real-time flow control and reduce experiments on in-cylinder flow field measurement and diagnostics.

Checking the Mechanisms of Internal Combustion Engines for the Presence of Parasitic Forces Using a New Methodology

This article presents the results of a study of internal combustion engines equipped with a crank mechanism according to the efficiency criterion using a new method for determining the operating efficiency of machines and engines. The study revealed the presence of parasitic forces in internal combustion engines equipped with a crank mechanism. The occurrence of parasitic forces present in internal combustion engines and the law of their dependence on the movement of the piston have been studied. As well as the negative impact of parasitic forces on engine efficiency. This article presents the main results of the study. As a result of the research, it was revealed that when converting the thermal energy generated in the combustion chamber of internal combustion engines equipped with a crank mechanism into mechanical work, more than 30% of the energy of the pressure force is spent on parasitic forces. The influence of the mechanical friction force (friction of the plain bearings) with the crankshaft on the effective torque was also studied. Thus, the inefficiency of internal combustion engines equipped with a crank mechanism has been theoretically and practically proven. Finally, recommendations are given for eliminating parasitic forces when designing new internal combustion engines. It is proposed to equip new internal combustion engines with mechanisms without parasitic forces. Equipping internal combustion engines with a mechanism that does not contain parasitic forces (that is, equipping them with more efficient mechanisms) significantly increases the possibility of efficient use of the thermal energy of the fuel introduced into the combustion chamber in internal combustion engines. Consequently, this increases the engine efficiency by 130%. or more. For internal combustion engines, a new mechanism is recommended that eliminates the loss of force and allows the use of rolling bearings. This feature of the new mechanism makes it possible to increase the efficiency of internal combustion engines by another 4-6%. From previous studies it is known that the efficiency of a rolling bearing relative to a plain bearing is more than 2-3 times.

Fabrication and characterization of thermal barrier coatings for internal combustion engines via suspension plasma spray with high solid loading

Suspension plasma spraying (SPS) technique producing thermal barrier coatings (TBCs) with high porosity and good thermal shock resistance has great potential to improve the thermal efficiency of internal combustion (IC) engines. However, its wide usage is limited by the immature fabrication technology and low spraying efficiency. Therefore, this study optimized the SPS process with high solid loading and characterized the properties of the coating to obtain TBCs suitable for IC engines. Suspension composition optimization revealed that polyethylenimide (PEI) has the best dispersion effect, and a suspension with high solid loading of 35 wt% was obtained. Furthermore, the effects of the spraying distance, feeding speed and spraying power on the coating microstructure were investigated, and the porosity and thermal shock resistance of the coatings were characterized to determine the optimal spraying process. Thermal shock failure of SPS coatings primarily arises from the propagation of horizontal cracks originating from vertical intercolumn cracks. The SPS coating with a feathery columnar structure has the best thermal shock resistance. By optimizing the spraying process, a coating with porosity up to 24.16 %, bonding strength of 41.69 MPa, and good thermal shock resistance is successfully achieved.

An original nondestructive sampling method to study the effect of gravity on the deposition of micron-sized large particles in exhaust gas recirculation (EGR) cooler fouling

Fouling is one of the barriers to developing more efficient and near-zero emission internal combustion engines. The micron-sized particulate matter is one of the roots of this fouling phenomenon in exhaust gas recirculation (EGR) coolers. This fouling is inadequately evaluated quantitatively, and its deposition mechanism is unknown. To investigate the effect of gravity on the deposition of micron-sized particles, an original nondestructive sampling fouling method and experiment apparatus have been developed to effectively obtain the upper and lower bottom fouling in the cooler in the direction of airflow, and the area proportion, count, and diameter of large particles in the fouling using image processing software. It was found that (i) the area proportion of large particles in the lower bottom fouling was almost 2.5 times higher than the upper bottom fouling; (ii) the count of large particles in the lower bottom fouling was higher, and the maximum diameter was larger, up to 639 μm; (iii) the mass of the lower bottom fouling was 1.5 times higher than the upper bottom fouling; (iv) gravity can significantly promote the deposition of micron-sized particles and should be considered in the design and arrangement of the EGR cooler to prevent fouling.

DESIGN AND CRANK TRAIN DYNAMICS OF VARIOUS APPROACHES TO CYLINDER DEACTIVATION SYSTEM FOR SPARK-IGNITION ENGINES

Due to the fact that emission reduction has become an important topic and due to the upcoming EURO 7 standard, the automotive industry is focusing on reducing the carbon footprint. One of the ways to do so is enhancing the efficiency of internal combustion engines by technologies such as cylinder deactivation. This technology offers fuel economy benefit, therefore, also CO2 emission reduction. However, implementing cylinder deactivation to modern engines with lower cylinder count can be challenging. The implementation requires numerous design modifications and some negative consequences like higher torsional vibration are associated with the technology. This paper focuses on investigating these constraints of cylinder deactivation.

Fullerene Oil Tribology in Compression Piston Rings under Thermal Considerations

To enhance the efficiency of automotive engines, a comprehensive understanding of friction generation within their components is paramount. Moreover, extensive global research efforts have been dedicated to nanoparticles, leading to the emergence of nanolubricants. In this study, an investigation was conducted focused on the piston ring–cylinder tribological interaction using fullerenes as additives. This is a very important issue since the friction forces can be significantly reduced. In order to solve this problem, a 2D CFD approach was implemented, taking into account a roughness model and temperature variations. The obtained results clearly show a friction reduction using fullerenes as additives compared to both synthetic and monograde oils. Furthermore, using fullerene oils, the performance of the compression piston ring system is improved due to friction reduction and the change of the temperature distribution. This study is beyond SOTA, since there is a limited contribution in the field of such nanolubricants in compression piston ring system. It is evident that the friction force is reduced by 42% compared to synthetic oils, showing a perspective on more tribologically efficient internal combustion engines.

Thermal efficiency optimization of a single cylinder gasoline engine based on active jet ignition

Jet ignition is a promising technology for improving the thermal efficiency of internal combustion engines (ICEs). To achieve the highest possible thermal efficiency, the jet ignition strategy was studied on a gasoline engine. Firstly, a combustion process featuring three stages of heat release, based on uniformly distributed jet ignition, was proposed. Next, the geometric structure of an active jet igniter was optimized using numerical simulations. Using the designed jet igniter, the effects of engine operating conditions were explored, including auxiliary fuel injection in the jet igniter, gross excess air ratio, and engine load and speed, with the goal of maximizing thermal efficiency. A highest indicated thermal efficiency of 50.3% was achieved, verifying the effectiveness of the proposed combustion strategy with uniformly distributed jet ignition. This study provides a technical reference for developing high-efficiency gasoline engines using jet ignition.

Exergoeconomic Analysis of a Mechanical Compression Refrigeration Unit Run by an ORC.

To improve the efficiency of a diesel internal combustion engine (ICE), the waste heat carried out by the combustion gases can be recovered with an organic Rankine cycle (ORC) that further drives a vapor compression refrigeration cycle (VCRC). This work offers an exergoeconomic optimization methodology of the VCRC-ORC group. The exergetic analysis highlights the changes that can be made to the system structure to reduce the exergy destruction associated with internal irreversibilities. Thus, the preheating of the ORC fluid with the help of an internal heat exchanger leads to a decrease in the share of exergy destruction in the ORC boiler by 4.19% and, finally, to an increase in the global exergetic yield by 2.03% and, implicitly, in the COP of the ORC-VCRC installation. Exergoeconomic correlations are built for each individual piece of equipment. The mathematical model for calculating the monetary costs for each flow of substance and energy in the system is presented. Following the evolution of the exergoeconomic performance parameters, the optimization strategy is developed to reduce the exergy consumption in the system by choosing larger or higher-performance equipment. When reducing the temperature differences in the system heat exchangers (ORC boiler, condenser, and VCRC evaporator), the unitary cost of the refrigeration drops by 44%. The increase in the isentropic efficiency of the ORC expander and VCRC compressor further reduces the unitary cost of refrigeration by another 15%. Following the optimization procedure, the cost of the cooling unit drops by half. The cost of diesel fuel has a major influence on the unit cost of cooling. A doubling of the cost of diesel fuel leads to an 80% increase in the cost of the cold unit. The original merit of the work is to present a detailed and comprehensive model of optimization based on exergoeconomic principles that can serve as an example for any thermal system optimization.

Potential use of graphene oxide as an engine oil additive for energy savings in a diesel engine

This study investigates the effects of graphene oxide (GO) nanosheets as an engine oil additive in fully synthetic SAE 10W-40 engine oil. GO concentrations in 0.5, 1.0, 1.5, and 2.0 mg/mL were added. The viscosity index (VI) increased by up to 7 % and thermal conductivity by 4–15 %. Tribological tests with a ball-on-disc mechanism showed that 1.5 mg/mL GO nanosheets additive gave the best results in reducing the coefficient of friction (COF) by 17 % and the total wear mass loss by 44 % on average. Based on the engine friction tests on the dynamometer, GO nanosheets reduced motored torque by up to 6 %, which represents the engine frictional losses, and improved mechanical efficiency by up to 2.8 % at certain engine speeds. An average improvement of 2.6 % in brake-specific fuel consumption (bsfc) and 2.7 % in brake thermal efficiency (bte) was observed across all engine speeds. The results of detailed engine tests suggest that the GO nanosheets additive has the potential to enhance the mechanical efficiency of internal combustion engines, leading to energy and fuel savings and indirectly contributing to reducing CO2 emissions.

Flame evolution and pressure dynamics of methane-hydrogen-air explosion in a horizontal rectangular duct

This work is aimed at exploring flame evolution and pressure dynamics of methane-hydrogen-air explosion experimentally and numerically by changing equivalence ratio and hydrogen content. For the flame evolution, the smooth distortion vanishes at equivalence ratio of Ф = 1.4, the prominent cellular structure and distorted tulip flame start to form with increasing hydrogen content. For the pressure dynamics, as the equivalence ratio increases, both maximum explosion overpressure and maximum pressure rise rate increase and then decrease, and both of them continue to increase with increasing hydrogen content. H + O2 = O + OH is the main elementary reaction with positive effect on the laminar burning velocity. The main elementary reactions with negative effects are H + O2(+M) = HO2(+M) and CH3 + H(+M) = CH4(+M). H radical always dominates on the rich side or the lean, stoichiometric side with high hydrogen content. As the hydrogen content increases, the main oxidation pathways of CH4 undergoes the transfer from CH4 → CH2(S) → CH2 → CO to CH4 → CH2(S) → CH2 → CH → CO → CO2. The research results are helpful to improve combustion efficiency of internal combustion engine and ensure process safety of hydrogen doped natural gas pipeline transportation.

Анализ концепции роторно-поршневого двигателя с реализацией цикла газотурбинного двигателя V = const

New conceptual solutions are required to significantly increase the internal combustion engine efficiency. Introducing external spool combustion chamber of constant volume and structural separation of the compression and expansion processes in its design are able to provide multi-fuel capacity, qualitative increase in the efficiency and significantly simplify the gearbox. In order to qualitatively improve characteristics of the internal combustion engine, systematic analysis of the created scientific and technical potential is required, followed by comprehensive implementation. The paper considers a concept of an internal combustion engine with continued expansion and ability to approach the gas turbine engine cycle implementation at constant volume with high efficiency on the example of such a basis using the rotary piston engine (CIAM) with the spool combustion chamber of constant volume (PJSC “UEC-Saturn”). The proposed concept makes it possible to effectively implement promising technologies for nitrogen separation and STIG technologies for further increase in the efficiency.

Influence of water electrolysis products on diesel engine performance in Colombia

Restrictions imposed by regulatory frameworks, the high cost of fuels, environmental impacts and the efficiency of internal combustion engines encourage research into reducing the consumption of fossil fuels. Additionally, to think about the alternative energy sources. In compression ignition engines, researchers around the world have been working for years on the use of biodiesel fuel, in order to reduce emissions and the consumption of diesel fuel. In other investigations, water electrolysis products obtained in an HHO gas generator and supplied to an internal combustion engine allow for improving performance, reducing fuel consumption and emissions. HHO gas is a mixture of hydrogen and oxygen resulting from the electrolysis process of water, with energy supplied by an electric source or accumulator. The main objective of this work is to evaluate the influence of an HHO generator products in a diesel engine that operates with diesel fuel produced in Colombia with 10 % biodiesel. The objective of this study is evaluated the influence of gas HHO on mechanical performance, fuel consumption, and polluting emissions in a single-cylinder diesel engine, performing a comparative analysis when the HHO generator operates with different amperages. The results showed a 25 % average reduction in fuel consumption between 1500 y 2500 engine revolutions when the HHO cell operated with 8 amperes. The breaking power maximum value increased a 10 %, and CO and PM10 emissions were reduced by 14 % and 53 %, respectively, at 1000 rpm. It is possible to conclude that supplying water electrolysis products in the fuel-air mixture increases the mechanical performance of a diesel engine and reduces polluting gas emissions. Additionally, research areas are opened in the development of HHO generators and standards for the application of this technology

Improving the Efficiency of Spark-Ignition Internal Combustion Engine Using a Novel Electromagnetic Actuator and Adapting Increased Compression

This paper presents an empirical study of a spark-ignition internal combustion engine with modifications made to increase its effectiveness. The modification was implemented bi-directionally in terms of changes to the compression ratio and changes to the engine’s valve train. The compression ratio was increased by 2.3 units by design and a hybrid intake valve opening control was used in the engine’s valve train. The hybrid control involved autonomous control of one of the inlet valves with a dedicated electromagnetic actuator. The designed electromagnetic actuator was mounted downstream of the single-cylinder engine’s intake system’s modified camshaft to control the effective compression pressure build-up. Field calculations were carried out for the electromagnetic actuator’s design variants and its current characteristics were determined. The multivariate calculations were carried out in order to find the quasi-optimal geometry of the actuator. The width and height of magnetic field coils and the dimensions of the stator poles were changed, while maintaining the same external dimensions of the actuator to enable its mounting in the cylinder head system. In the next step, the prototype of the actuator was made and placed on the combustion engine in order to conduct the experimental investigations. The work was aimed at improving the internal combustion engine’s efficiency at the low load range, as this is load range in which it has low efficiency despite it being the most often used during normal vehicle operation. The original measurement stand was prepared, and many tests were carried out in order to investigate the influence of the electromagnetic valve on the combustion engine characteristic. This improved the internal combustion engine’s efficiency at its low-load range by up to 25%. Both calculation and measurement results are presented in form of graphs.

Effects of temperature and pressure fluctuations on exergy loss characteristics of hydrogen auto-ignition processes

Intake temperature and pressure fluctuations prior to main ignition are one of the reasons affecting the efficiency of internal combustion engines. In this study, the effects of temperature and pressure fluctuations with varied amplitudes and frequencies on the exergy loss of hydrogen auto-ignition processes were numerically investigated in an adiabatic constant-volume system at engine-relevant conditions. The results revealed that the increase in temperature fluctuation amplitudes primarily decreases the exergy loss due to chemical reactions, and the exergy loss due to incomplete combustion remains unchanged. Specifically, the total exergy loss is reduced by approximately 1.5% with a temperature fluctuation amplitude of 100 K at a frequency of 2 ms−1. Furthermore, with the same temperature fluctuation amplitude, increasing the frequency of temperature fluctuation from 2 ms−1 to 7 ms−1 leads to a 0.7% increase in the total exergy loss. On the other hand, the effects of pressure fluctuation on the exergy loss of hydrogen auto-ignition processes are negligible compared with those of temperature fluctuation. Through chemical kinetic analysis, it is found that temperature fluctuation promotes the consumption pathway of O2 to generate OH, rather than the collision with H to produce HO2. Consequently, the reduced mole fraction of HO2 inhibits the related HO2-consumption reactions, including HO2+HOH + OH and HO2+HO2H2O2+O2. Moreover, with temperature fluctuation, due to the lower fraction of third-body collision molecules, H2O, the reactivity of the third-body reaction, H + O2+M=HO2+M, is decreased. The reduced reaction rates of these reactions lead to decreased total exergy loss, indicating that the fuel energy conversion process may benefit from temperature fluctuation.