Top Dead Center Research Articles

The Role and Impact of Al2O3 Additive on the Performance of the Diesel Engine Operated by JFO Along With Its Measures of Combustion and Emissions

ABSTRACTThe world's biggest problems are global warming and fossil fuel depletion. Most fast‐developing countries are facing problems. Most engines that burn crude oil–based products discharge smoke, carbon monoxide, nitric oxide, unburnt hydrocarbon, and lower‐concentration particulate matter into the environment. In this study, good planning and emissions rules are reducing crude oil use. Juliflora oil biodiesel is derived from Juliflora seeds and tested in a single‐cylinder direct injection diesel engine. If you use biodiesel in your engine without changes, you may encounter gum formation in the cylinder, knocking, and carbon deposits. The blends approach is one of many techniques to change biodiesel's attributes, but our present intention is to employ it. B20 blend outperforms the other sample fuels and is closest to diesel. The produced aluminum oxide was tested for parameters using X‐ray diffractometer and scanning electron microscope. Aluminum oxide was blended with biodiesel using an ultrasonicated to mix 25, 50, and 75 parts per million (PPM) aluminum oxides, designated B20AO25 PPM, B20AO50 PPM, and B20AO75 PPM. For typical engine running and optimal engine operating parameters, biodiesel with aluminum oxide nanoadditives was investigated. Optimized characteristics are 80% diesel and 20% Juliflora seed oil with 75 PPM aluminum oxide nanoadditives (B20AO75 PPM) at 200 bar injection pressure and 21° before top dead center injection time.

Experimental and computational fluid dynamics analysis on the influence of fuel injection pressure on engine's behavior of a gasohol based gasoline direct injection engine

AbstractThis work examines the impact of fuel injection pressure (FIP) on engine's behavior of a multi cylinder gasoline direct injection (GDI) engine using gasohol (85% gasoline+15% ethanol by mass) as fuel. The FIP was varied from 90r to 120 bar at 10 bar intervals with the fuel injection timing 320° before top dead center (BTDC). experiments were performed at variable power at a constant speed of 2500 rpm. Computational fluid dynamics (CFD) simulations were carried out for the above said conditions to understand engine's behavior. Considering the conventional FIP (i.e.90 bar), increasing the FIP showed improvement in engine's brake thermal efficiency (BTE) up to110 bar. The maximum BTE was observed as 33.5% at the engine power output of 21 kW (where as it was 27.2% with the FIP of 90 bar). CFD results confirmed the improvement in the air‐fuel mixing rate and swirl motion due to the increased FIP. The hydrocarbon (HC) and carbon monoxide (CO) emission were reduced with increased FIPs. CFD results on the HC and CO emissions indicated well agreement with the experiments. With the higher injection pressures, oxides of nitrogen (NOx) emissions showed an increase at all loads. The in cylinder pressure was observed to be higher with higher FIPs. It is concluded that increasing the FIP might improve performance and lower HC and CO emissions of a Gasohol based fuel in GDI engine. The optimized FIP of 110 bar could be recommended for the aforementioned engine's greatest performance without any modifications in the engine design while injecting the fuel at 320° BTDC. Increase in NOx emissions at higher injection pressure needs attention. The present study restricted the amount of ethanol as 15% by mass. Higher proportions of ethanol admissions require major modifications in the engine design.

Analysis of energy, exergy, and emissions in a diesel engine powered by cotton silk seed oil biodiesel with varying injection timings.

To mitigate the exhaustion of hydrocarbon fuels and the rise of pollutants, one can use biofuels in diesel engines for power generation. This study examines the possibility of enhancing the performance and reducing the pollutions of a compressed ignition engine using methyl ester made from cotton silk seed oil. This study aimed to assess the energy, energy efficiency, and emissions (3E) of the Kirloskar engine operating at 1800rpm. The test involved changing the injection timings at 21° bTDC, 23° bTDC, 25° bTDC, and 27° bTDC, as well as variable load settings at 25%, 50%, 75%, and 100%. A mix of 20% was used in the test. The results indicate that a 23° bTDC delay in injection timing improves the efficiency, reduces exergy destruction, and decreases emissions when using cotton silk seed oil biodiesel in a diesel engine. The maximum brake thermal efficiency was achieved when the injection timing was set at 23° before top dead center under 100% load conditions. The study found that nearby was a 38.8% decrease in CO emissions and a 19.23% reduction in unburnt hydrocarbon emissions while using the same injection timing. However, there was an average rise of 10.12% in NOX emissions compared to diesel mode. The cotton silk seed oil biodiesel was used as a substitute fuel in the test engine to achieve improved optimal outcomes.

Vibration characteristics of a compression ignition engine fuelled with different biodiesel-diesel blends

Biodiesel has wide application prospects due to its good power performance, fuel economy and emission reduction. Experimental studies have found that the measured engine vibration presents an N-shaped nonlinear trend with the increase of the biodiesel proportion in blends, which cannot be explained solely based on the combustion characteristics of blended fuels. To study the mechanisms for this nonlinear trend of engine vibration, a two-degree-of-freedom nonlinear model of piston–cylinder system was established and verified to analyse the correspondence between in-cylinder combustion behaviour and engine dynamic responses. By correlating simulation results with measured signals, it is found that the root cause of the nonlinear vibration trend is the coupling effect of in-cylinder pressure and piston inertial force. The time integral of piston lateral force in the interval from combustion top dead centre (TDC) to the subsequent piston slap ultimately determines the trend of liner vibrations. These key findings pave the fundamentals for the vibration analysis of engines fuelled with other alternative fuels, which is important for improve engine operation performances including reliability assessment and NVH control.

A study on misfire control using crank angular velocity combustion feedback considering in-cylinder gas properties

Internal combustion engines have been strongly required to improve thermal efficiency and utilize a variety of fuels derived from renewable energy sources to achieve carbon neutrality. In terms of engine development, the stable control of ignition and combustion is the primary challenge in adapting to diverse fuels for the recently emphasized premixed compression ignition combustion and super lean burn. In this study, a misfire index was used as a detector for a premixed type of diesel combustion engine. Combustion feedback control was performed to control the target value of EGR based on the difference between the misfire index and its target value. To apply crank angle velocity to feedback control, this study implemented corrections and limitations to the misfire index based on in-cylinder gas properties. This was made possible because, during misfire events, the in-cylinder pressure at top dead center (TDC) is not influenced by combustion pressure. Additionally, this research enabled model validation of the phenomena for the first time. A novel structure was also established to learn the EGR correction amount from the deviation of the misfire index, marking the first empirical demonstration of its effectiveness. This research not only presents control examples for misfire countermeasures, which are crucial for the development of engines capable of utilizing diverse fuels but also contributed to mass production and practical application.

Self-Learning Method for Shift Hub Position in a Double-Input Shaft Hybrid Gearbox Using Linear Active Disturbance Rejection Control and Nutcracker Optimization Algorithm

<div>Due to manufacturing, assembly, and actuator wear, slight deviations between the actual and logical positions of various gears in a transmission system may accumulate, affecting shift quality, reducing shift accuracy, and causing operational anomalies. To address this issue, a self-learning method based on the top dead center (TDC) and lower dead center (LDC) was proposed, specifically for the hybrid gearbox of an electric torque converter (eTC) module and a double-input shaft gearbox (DIG). The linear active disturbance rejection control (LADRC) method was employed to estimate and manage the nonlinear resistance during the motion of the shifting motor. To simplify the controller parameter problem, the nutcracker optimization algorithm (NOA) was utilized to tune the LADRC parameters, thereby optimizing the position self-learning process. The control strategy was modeled using MATLAB/SIMULINK, and its reasonableness was verified through hardware-in-the-loop (HIL) tests. Based on these tests, the approach was applied to three controllers: the PID controller, LADRC, and NOA_LADRC. Subsequent gearbox bench experiments showed that the self-learning method successfully corrected gear positions during product launch and shifting. Among these controllers, NOA_LADRC effectively addresses nonlinear disturbances, reducing the time required for identifying the shift drum position by 0.06 s and 0.36 s, respectively. It provides critical parameters for the control of the shift actuator, thereby optimizing shift performance and indirectly enhancing overall performance.</div>

Impact of Fuel Injection Pressure and Timing on the Performance and Emissions of a Low Heat Rejection CI Engine with Fish Oil Methyl Ester, DEE and Butanol Blend

This study examines how different fuel injection pressures and timings affect the performance and emissions of a Low Heat Rejection (LHR) engine running on blends of fish oil methyl ester, diethyl ether, and butanol. Results indicate that optimizing the injection pressure up to 230 bar enhances engine performance, fuel efficiency, and emission control. Research supports that increasing fuel injection pressure improves performance and combustion characteristics. For instance, studies have shown that high injection pressures can reduce and soot emissions without compromising fuel economy. The depletion of petroleum resources, rising car use, and environmental concerns have made the demand for alternate fuels more urgent. Fish oil methyl ester, which is made from fish oil and may be made from animal fats and edible and non-edible oils, offers a possible substitute for biodiesel. Diesel engines are prized for their effectiveness, dependability, and longevity; timing and fuel injection pressure have a big impact on emissions and performance. However, higher pressures show diminishing benefits, and fine-tuning the injection timing to 29° before top dead centre further improves efficiency and reduces emissions. This research highlights the crucial role of optimizing injection parameters to maximize engine performance and reduce emissions when using alternative fuels.

Optimization of Injection Timing and Ethyl Hexyl Nitrate Additive Effects on Diesel Engine Characteristics Using Rubber Seed Oil Biodiesel

The use of biodiesel is becoming inevitable due to the depletion of fossil fuel resources. Biodiesel is an attractive alternative fuel derived from natural oils and can be used directly in diesel engines with no major change. However, various biodiesels may exhibit different performance behaviors and emission characteristics, with some performing worse than diesel fuel. The present research work investigates the performance, combustion, and emission behavior of rubber seed biodiesel (RSB)/diesel blends (B20, B30, B40) and B20 + ethyl hexyl nitrate (EHN) at four injection timings (19°, 21°, 25°, and 27° before top dead center [BTDC]) in a single‐cylinder DI diesel engine. Combustion of biodiesel/diesel blends generally resulted in worse performance, except smoke emission. The addition of EHN reduced hydrocarbon (HC) emissions but negatively impacted brake‐specific fuel consumption (BSFC) and brake thermal efficiency (BTE). However, advanced injection timing not only restored the combustion parameters to the B20 level but also brought them closer to those of the diesel engine. Advancing the injection timing to 27° BTDC improved BSFC and BTE by 3% and 4% compared to B20, respectively. Additionally, the HC emission decreased strongly by 80% and 73%, and smoke emission decreased by 15% and 16%, respectively, compared to B20 and diesel fuel values. A slight improvement in NOx emissions (by 2%) was also observed compared to B20. An increase in cylinder pressure from 66.2 to 67.4 bar was observed with advanced injection timing, contributing to improved engine performance. Analysing of combustion characteristics showed that RSB/diesel blends, when doped with EHN, offer better performance at advanced injection timings making them a suitable alternative fuel to replace diesel fuel usage in developing countries like India.

Impact of compression ratio, fuel injection pressure and timing on the behaviour of compression ignition engine operating with ethanol-enriched WCOME blends

Compression ignition engines’ performance, emission and combustion characteristics are studied using ethanol-enriched waste cooking oil methyl ester (WCOME) varying compression ratio, fuel injection pressure and timing under full load conditions. The fuel blend of base fuel (10% WCOME and rest diesel) with 5% ethanol was tested at different compression ratios of 18, 19, 20 and 21; injection pressures of 200, 220, 240 and 260 bar, and injection timing of 21°, 23°, 25° and 27° before top dead centre. The carbon monoxide, hydrocarbon emission and smoke opacity of the blend were 16.3%, 19.6% and 36.8% less respectively than that of diesel at a fuel injection pressure of 240 bar. The lowest brake-specific energy consumption obtained is 1.06% less than that of diesel. Higher brake thermal efficiency, lower brake specific energy consumption, and reduced carbon monoxide and hydrocarbon emissions except nitrogen oxides are obtained for fuel injection timing of 25° before the top dead centre. The peak of cylinder pressure at 65.47 bar is obtained for the fuel blend at 9° after the top dead centre and 240 bar fuel injection pressure.

A Comparative Design and Analysis of Conventional and Variable Connecting Rod of Engines

Geometric compression is one of the primary design parameters for internal combustion engines. It is determined by the maximum volume ratio of the combustion chamber between the bottom dead center (BDC) and the minimum size of the combustion chamber in the position of the top dead center (TDC). In this study, a new motor was designed with a variable compression ratio (VCR) to enhance its performance. The comparison between the conventional engine and the turbo variable compression was analyzed using SolidWorks software. The results showed the advantages of VCR due to the change in performance according to changes in the required torque by varying the connecting rod stroke.

Patterns of lean methane-air mixtures combustion in piston engine

The article is devoted to the study of the patterns of combustion of lean methaneair mixtures in marine internal combustion engine. Literature review shows that the implementation of combustion technology for a homogeneous lean methaneair mixture will increase the compression ratio, reduce fuel consumption and improve the environmental engine performance. However due to an increase in misfires and a decrease in the speed of flame propagation, the combustion of lean methaneair mixtures remains an unresolved problem. The article studies the influence of the excess air coefficient (from 1 to 1.4) on the turbulent combustion regime (assessed by the Karlowitz and Damkoehler criteria), the completeness and rate of fuel combustion. It was revealed that depletion of the air fuel mixture under conditions of intense turbulence leads to an increase in the Karlowitz criterion and a decrease in the Damköhler criterion. This indicates that the rate of chemical reactions in the flame front decreases, as a result of which the combustion process is characterized by stretching and rupture of the flame front. Therefore, to intensify the combustion of lean methaneair mixtures, it is advisable to increase the average speed of the vortex flow, and not the intensity of turbulence. A study of the influence of the excess air coefficient on the completeness and rate of fuel combustion showed that depletion of the mixture leads to a decrease in the completeness of fuel combustion from 93.5 % (at α=1) to 83 % (at α=1.4). The combustion rates also decrease and their maximum values shift from 13° (at α=1) to 24° (at α=1.4) degrees after top dead center. Therefore for efficient engine operation on lean mixtures, it is necessary to increase the fuel combustion rate through additional swirling of the gasair mixture or the use of combustion promoters.

A Novel Friction Mean Effective Pressure Model for a Heavy-Duty Diesel Engine by Neural Network and Its Applications to Heat Release Rate Profile Optimization

<div>The prediction of friction mean effective pressure (FMEP) is important when engine performance is estimated in the model-based development process. The Chen–Flynn model as a function of the maximum in-cylinder pressure (P<sub>max</sub>) and mean piston speed (C<sub>m</sub>) is often used to predict FMEP because of its simplicity to utilize; however, this study inferred from the results of multiple regression analysis between FMEP and factors related to combustion phase and rate of heat release profile (ROHR) that the Chen–Flynn model may be difficult to accurately estimate FMEP in a modern diesel engine with common rail fuel injection system, which allows the control of fuel injection pressure (P<sub>inj</sub>) and combustion phase. In this study, a neural network with machine learning was applied to predict FMEP based on the expectation that the ROHR profile, which allows the reduction of FMEP may be possible to be found. 7666 points experimental results that include FMEP and combustion parameters in the heavy-duty single-cylinder diesel engine were utilized as training and validation data for machine learning. The pre-trained neural network prediction model for FMEP can predict the tendency of FMEP better than the Chen–Flynn model when start of combustion (SOC) and P<sub>inj</sub> were varied. The error between the predicted FMEP results by the pre-trained neural network and the experimental results of FMEP were within 4% of the experimental results when SOC was advanced from top dead center to −7 deg. ATDC. Whereas, the predicted FMEP by Chen-–Flynn model had a maximum error of 15% compare to the experimental results. Furthermore, the predicted FMEP by Chen–Flynn model had a maximum error of 9% compare to the experimental results when P<sub>inj</sub> was varied from 120 MPa to 200 MPa, whereas the error between the predicted FMEP results by the pre-trained neural network and the experimental results of FMEP were within 4% of the experimental results. The pre-trained neural network model was confirmed to be predictive better than the Chen–Flynn under the conditions that the combustion phase and P<sub>inj</sub> are changing. In addition, the parameter study using the pre-trained neural network prediction model for FMEP and a one-dimensional engine performance simulation tool was conducted to find the ideal ROHR profile that improve brake thermal efficiency (BTE). The result of parameter study suggests that the optimum ROHR profile to improve BTE under the same conditions of P<sub>max</sub> and the degree of constant volume combustion is to shorten combustion duration and to retard the peak of ROHR away from top dead center.</div>

Effects of injection timing on combustion and mixture formation of a methanol direct injection engine equipped with a small volume passive pre-chamber

Effects of injection timing on combustion and mixture formation of a methanol direct injection engine equipped with a small volume passive pre-chamber

Numerical investigation on the effect of ignition timing on a low-temperature hydrogen-fueled Wankel rotary engine with passive pre-chamber ignition

Numerical investigation on the effect of ignition timing on a low-temperature hydrogen-fueled Wankel rotary engine with passive pre-chamber ignition

Development of prechamber enabled mixing-controlled combustion strategy for ultra-low methane emissions from lean burn natural gas engines

This numerical study explores the optimization of Prechamber Enabled Mixing-Controlled Combustion (PC-MCC) using natural gas in heavy-duty engines, aiming to enhance combustion efficiency to minimize methane slip and NOx emissions. The approach involves a prechamber ignition system, distinct from conventional spark ignition (SI) systems, to initiate combustion of direct injected natural gas. By leveraging the robust ignition characteristics of the prechamber, the PC-MCC method demonstrates significant potential in achieving efficient combustion akin to diesel engines but with lower greenhouse gas emissions. The research evaluates the effects of various geometric and operational parameters on the combustion process and emissions, including prechamber volume, nozzle diameter, direct injector (DI) geometry, and engine operating strategies. Computational Fluid Dynamics (CFD) simulations are utilized, focusing on a heavy-duty, single-cylinder engine modeled after the Caterpillar C9.3B engine. Key findings indicate that a prechamber volume of 3 cc, coupled with a nozzle diameter of 2.75 mm for two prechamber holes, strikes an optimal balance between combustion efficiency and emissions reduction. This configuration ensures robust combustion across a range of operating conditions while maintaining methane slip within targeted limits. Further investigation into DI geometry shows the significance of the injector umbrella angle and nozzle diameter in shaping the fuel-air mixing and combustion dynamics. An umbrella angle of 130° and a nozzle diameter of 300 microns are identified as optimal, promoting rapid and efficient combustion with minimized methane and NOx emissions. The study also investigates the impact of injection timing and pressure, highlighting their roles in controlling combustion timing and influencing emissions levels. Advanced injection timing is found to be crucial in achieving the desired low methane slip, whereas retarded injection timing assists to reduce NOx emissions while having a slight increase in methane emissions. Operating strategies incorporating various levels of Exhaust Gas Recirculation (EGR) are assessed for their effectiveness in further reducing emissions. The research demonstrates that a judicious combination of internal hot EGR and careful calibration of DI pressure and SOI timing can achieve significant reductions in NOx emissions while keeping methane slip under control. Specifically, an internal EGR level of 15%–25%, combined with DI pressures of 200–300 bar and injection timings at or after top dead center, is recommended. These findings contribute valuable insights into the development of advanced combustion techniques for natural gas engines, offering a viable pathway to reduce methane slip without compromising engine efficiency or performance. The PC-MCC system presents a promising solution for the future of heavy-duty natural gas engine technology to reduce methane emissions.

Experimental study of combustion and emissions characteristics of low blend ratio of 2-methylfuran/ 2-methyltetrahyrofuran with gasoline in a DISI engine

The nearing depletion of fossil fuels and the possible consequences of its emissions on the global climate has prompted a worldwide probe for their alternatives. 2-methylfuran and 2-methyltetrahydrofuran are considered promising alternative fuels for spark ignition engines. In this study, the combustion and emission characteristics of low blending ratio MF20 (2-methylfuran 20 %, gasoline 80 % by volume) and MTHF20 (2-methyltetrahydrofuran 20 %, gasoline 80 % by volume) were first implemented and compared to neat gasoline in a single-cylinder direct injection spark ignition engine. The combustion performance of the test fuels was analyzed across a range of loads from 3.5 to 8.5 bar indicated mean effective pressure and fuel injection timings between 180 and 280 crank angle degrees before top dead center. Meanwhile, the compositions of the hydrocarbon emissions were experimentally investigated using the Fourier Transform Infrared Spectroscopy technique. Results show that MF20 exhibits advanced spark timing flexibility of 8 and 7 crank angle degrees before top dead center compared to the unleaded gasoline and MTHF20 respectively at the peak load. MTHF20 exhibits the highest maximum cylinder pressure at medium load compared to other fuels but drops sharply at peak load accompany with the audible knock. Additionally, MTHF20 exhibits specific fuel consumption advantage over MF20 across the entire load range. The unburned furan of the total hydrocarbon emissions was recorded to be 3 % of total hydrocarbon emissions. The concept of low blending ratio furan-based fuel proposed could provide a solution for the transition period of carbon neutrality.

Effects of Scavenging-Port Semi-Direct Injection Strategy on Mixture Formation for a Two-stroke Spark Ignition Kerosene Piston Engine

Abstract The two-stroke spark ignition (SI) kerosene piston engines (KPE) are commonly utilized in lightweight unmanned aerial vehicles (UAV). The quality of mixture formation is crucial for the engine performance. This paper investigates the mixture quality in a semi-direct injection (SDI) SI KPE. Computational models were established using a 1D simulation tool and a 3D computational platform to analyze the effects of injection pressure, injection timing, and fuel temperature on atomization and mixture formation. The results indicate that increasing injection pressure promotes a more uniform mixture distribution. Higher injection pressures also enhance the formation of fuel film. At the top dead center (TDC), the average equivalence ratio (ER) with an injection pressure of 0.7 MPa is 3.8% higher than that of 0.3 MPa and 1.9% lower than that of 0.5 MPa. Delaying the injection timing increases the pressure difference between the cylinder and scavenging port, weakening fuel penetration and improving the fuel gasification rate. When the injection timing is set to 180 °CA ATDC, the average ER at TDC is 10.4% higher than that at 140 °CA ATDC, with a 6.6% decrease in fuel capture rate. Increasing fuel temperature effectively enhances the fuel gasification rate. However, excessively higher fuel temperatures will not significantly improve mixture quality. At a fuel temperature of 380 K, the average ER at TDC is 2.9% higher than that at 340 K. Response surface analysis reveals that the control parameters affect the average ERs in the following order of influence: injection timing, fuel temperature, and injection pressure. This study provides theoretical support for optimizing control parameters in SDI SI KPEs.

Effect of fuel characteristics coupled with injection parameters on oil–gas mixing and combustion processes in diesel engines

Effect of fuel characteristics coupled with injection parameters on oil–gas mixing and combustion processes in diesel engines

Reductions in GHG and unburned ammonia of the pilot diesel-ignited ammonia engines by diesel injection strategies

Reductions in GHG and unburned ammonia of the pilot diesel-ignited ammonia engines by diesel injection strategies

Multi‐aspect assessment and multi‐objective optimization of preheated tallow biodiesel‐diesel blend as alternate fuel in CI engine

AbstractThis study meticulously examined the impact of preheated tallow biodiesel on the performance and emission characteristics of a diesel engine. Employing a single‐cylinder, water‐cooled diesel engine configured with exhaust gas recirculation in this investigation, exhaust gas temperature (EGT) could be used to preheat the biodiesel, reducing its viscosity and density. This improvement in viscosity and density could enhance the injection process, which is often hindered by the higher density and viscosity of biodiesel compared with diesel fuel. The investigation achieved a peak preheat temperature of 70°C for the biodiesel, leading to notable improvements in brake thermal efficiency and brake power, particularly under high‐load conditions. A significant reduction in emissions was observed, with hydrocarbon and carbon monoxide levels decreasing by 46.87% and 50%, respectively, when using preheated biodiesel. To refine the engine's performance further, this study utilized response surface methodology (RSM) for the optimization of operational parameters, including injection timing, engine load, and biodiesel preheat temperatures. Optimal conditions were identified at an injection timing of 21° before top dead centre, a preheat temperature of 64°C, and an engine load of 45.45% for which output response was 18.68% brake thermal efficiency, 307°C EGT, 0.0247% vol. CO, 15.32 ppm hydrocarbons, and 131.37 ppm nitrogen oxides (NOx). The successful implementation of preheated tallow biodiesel signifies a crucial step forward in the pursuit of a more sustainable and efficient transportation industry. This advancement holds the promise of reducing reliance on traditional fossil fuels, thereby contributing to the global efforts towards achieving a more environmentally friendly energy landscape.