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A direct injection (DI) CNG engine was developed and evaluated under stoichiometric and lean burn conditions, emphasising high compression ratios (CRs). A comparative analysis of PFI gasoline and PFI CNG engines was conducted to provide comprehensive insights. Results showed that the DI CNG engine exhibited a shorter combustion duration, indicating higher combustion speed, and enhanced combustion stability, particularly at low load and speed conditions, with a reduced coefficient of variation of indicated mean effective pressure (COVIMEP) below 1%. The DI CNG engine demonstrated a relative increase in net indicated thermal efficiency by 4–5% compared to the PFI CNG engine. Furthermore, CNG engines operating at a high compression ratio of 16 could run at high loads without encountering knocking issues. Lean burn operation, combined with high compression ratios, improved thermal efficiency while minimising emissions; however, challenges such as combustion instability and increased emissions under lean burn conditions were observed. [ABSTRACT FROM AUTHOR]

One of the suitable solutions for burning natural gas in diesel engines is the use of dual-fuel technology. In this study, the MT440C compression ignition engine has been converted to dual fuel (diesel + CNG) simultaneously combustion of diesel fuel and natural gas, with the least amount of engine changes and using the most amount of natural gas. The ignition of the engine was in the range of the governor. Experiments in stable conditions for the working modes of the engine were performed with pure diesel fuel and mixed gas diesel fuel. The effects of natural gas fuel as the main fuel and diesel fuel as the spark ignition on a 4-cylinder compression ignition engine were investigated on the performance and emissions. According to the engine speed and load, the amount of diesel-fuel injection was adjusted by making mechanical changes in the governor, while the ignition system was not used. These tests were performed at engine speeds of 1,200, 1,400, 1,600, 1,800, and 2,000 rpm, using single diesel fuel and dual fuel (diesel + CNG). These data were collected in the Engine Research Center of Tabriz Motorsazan Company, and experimental runs were repeated three times One of the goals of this research is to reduce the consumption of diesel fuel, and in the current study, compressed natural gas (CNG) is 72% and diesel is 28% of the dual fuel in idling. This study showed that the emission of some pollutants increased and some decreased in the dual-fuel mode. Therefore, more research is needed on modifying the diesel injection system as a spark plug or the CNG injection system to reduce the emission of greenhouse gases.

Most of the vehicles used by Malaysians have engines that only require petrol RON 95 to power the engine. However, many people claimed that utilising RON 100 instead of RON 95 for their vehicles will improve engine performance. Furthermore, many people speculate that using oil with a low octane level in an engine with low performance will affect the engine's performance. The goal of this research is to analyse and compare the engine performance and emissions on a spark ignition engine using gasoline RON 95 and RON 100. In this study, a single-cylinder four-stroke engine running with RON 95 and RON 100 has been tested on an engine dynamometer to evaluate the brake power, torque, specific fuel consumption, and exhaust emissions. The emissions from the engines have been determined using a gas emissions analyser. The outcomes of the experiment have been analysed based on engine torque, braking power, and exhaust emissions. Based on the analysis, torque, brake power, and emissions data obtained from the dynamometer engine, RON 100 has a higher and smoother performance than RON 95. [ABSTRACT FROM AUTHOR]

Since traditional fuels are being phased out, engine conversions to more sustainable fuels are being performed to address local regulations. Due to its potential to reduce CO2 and local pollutants, liquified petroleum gas (LPG) stands out as an alternative fuel for internal combustion engines. LPG chemical structure allows for higher compression ratios (CR) and improved thermal efficiency. However, studies indicated that increasing the CR may lead to knocking combustion. In this investigation, an engine conversion to LPG was analyzed using two LPG formulations, commercial propane (93.91% propane) and autogas (38.42% propane − 60.37% butane). First, using a numerical methodology previously proposed for estimating the event of knock based on the thermochemical characteristics of the fuel. Low-order methods are utilized in combustion simulations to estimate autoignition delay (AID) and laminar flame speed (sL). Second, an experimental validation was performed with a 4-cylinder turbocharged SI engine. It was tested with three different CRs: 12.45:1, 11.05:1, and 9.86:1. Simulation indicates that autogas exhibits a significantly higher tendency to knock compared to commercial propane. Experimental results confirm the occurrence of knocking when using autogas with a CR of 12.45:1, resulting in a 29% reduction in the engine maximum torque compared to commercial propane. Reducing compression to 9.86:1 minimizes the occurrence of undesired knocking. It also leads to a decrease in thermal efficiency by 3.8% for autogas and 4.5% for commercial propane. [ABSTRACT FROM AUTHOR]

In this study, deep learning (DL) model is used to predict brake power (BP) of GX35-OHC 4-stroke, air-cooled, single-cylinder gasoline engine. The engine uses E15 (85% gasoline + 15% ethanol) as a fuel due to its high performance and low emissions. A convolutional neural networks (CNN) model is used on time-series data due to their ability to capture temporal patterns and relationships in sequential data, such as engine BP. While studying the performance of the network, it is found that the root mean squared error (RMSE) is 0.0007, explained variance score (EVS) is 0.9999, and mean absolute percentage error (MAPE) is 0.22%. Compared to traditional machine leaning methods, these metrics demonstrate the high accuracy and reliability of the model, confirming its effectiveness in predicting BP. Various performance curves are plotted such as comparing target and predicted values, regression plots (to indicate the generalization capability), learning curve (to demonstrate the model's effective training progress and convergence), Bland-Altman plot (to show the convergence between the actual and predicted values), histogram and density plot (to show a close fit between predicted and actual values), density plot of actual and predicted outputs, and residual plot (to show randomly distributed errors). This high accuracy and reliability of this DL model help in effective real-time engine performance monitoring, and reducing emission levels, especially for the adoption and use of renewable fuels like E15. [ABSTRACT FROM AUTHOR]

The automotive industry is increasingly challenged to develop cleaner, more efficient solutions to comply with stringent emission standards. Hydrogen (H2)-powered internal combustion engines (ICEs) offer a promising alternative, with the potential to reduce carbon-based emissions and improve efficiency. However, hydrogen combustion presents two main challenges related to the calibration process: emissions control and measurement of the air excess coefficient (λ). Traditional lambda sensors struggle with hydrogen's combustion dynamics, leading to potential inefficiencies and increased pollutant emissions. Consequently, the determination of engine performance could also be compromised. This study explores the feasibility of using machine learning (ML) to replace physical lambda sensors with virtual ones in hydrogen-fueled ICEs. The research was conducted on a single-cylinder spark-ignition (SI) engine, collecting data across a range of air excess coefficients from 1.6 to 3.0. An advanced hybrid model combining long short-term memory (LSTM) networks and convolutional neural networks (CNNs) was developed and fine-tuned to accurately predict the air–fuel ratio; its predictive performance was compared to that obtained with the backpropagation (BP) architecture. The optimal configuration was identified through iterative experimentation, focusing on the neuron count, number of hidden layers, and input variables. The results demonstrate that the LSTM + 1DCNN model successfully converged without overfitting; it also showed better prediction ability in terms of accuracy and robustness when compared with the backpropagation approach. [ABSTRACT FROM AUTHOR]

Ethanol fuel is considered a renewable energy source with a lower global warming potential than gasoline. The purpose of this paper is to analyze the emissions and performance of gasoline-ethanol blends in SI engines under various conditions. A computerized 4s, 1cyl, VCR spark ignition engine is used for the tests to measure the performance of Gasoline-Ethanol (GE) blends in particular E-10 (10% ethanol, 90% gasoline). For measuring exhaust emissions as well as performance, regular gasoline fuel is used for the additional tests. Engine performance using ethanol-gasoline blended fuel has been evaluated at different working conditions: 1200-1800 rpm, AFR 0.9, STs 300, CR10:1. When vehicles running on ethanol-gasoline blend indicated a decrease in the amounts of HC, NOx, and CO exhaust gases while 3.9% increase in CO2 emissions as compared to unleaded gasoline fuel. Furthermore, it has been shown that the brake power, torque, specific fuel consumption increases when a Gasoline-Ethanol (GE) blend is used over regular gasoline fuel. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical evaluation of the pre-chamber induced HCCI combustion concept (PC-HCCI) in terms of engine performance, emissions, and controllability. In this concept, a spark-initiated combustion in the pre-chamber is utilized to trigger the kinetically controlled combustion of an ultra-lean mixture in the main combustion chamber. The experimental measurements were performed on a single-cylinder engine with a custom-made active pre-chamber. A high compression ratio of 17.5 was used, which limits the maximum achievable engine load due to high knocking tendency but enables both standard PCSI combustion (flame propagation) at very high dilution levels and HCCI combustion at reasonable intake temperatures. The analysis of combustion characteristics and the resulting performance is performed at indicated mean effective pressures (IMEPs) of 3.5 and 3.0 bars, and three different intake temperatures of 80 °C, 90 °C, and 100 °C. The variation in engine load was achieved by adjusting the excess air ratio in the main chamber. On each combination of intake temperature and engine load, a spark sweep and an injected PC fuel mass sweep were performed to obtain the highest indicated efficiency while satisfying the restrictions in terms of combustion stability and knock intensity. It was shown that, unlike in a conventional HCCI engine, the combustion phasing can be directly and reliably controlled by adjusting either spark timing or the reactivity of the pre-chamber mixture, ensuring adequate combustion stability and eliminating potential misfires. A similar indicated efficiency as with conventional HCCI combustion was obtained, while the NOx emissions, although slightly elevated, are still insignificant. Compared to PCSI combustion at the same engine load, a 4-percentage-point increase in indicated efficiency and two times lower NOx emissions were achieved. Compared to the most efficient PCSI operating point, it was 1 percentage point lower, indicating that efficiency was achieved, but the specific NOx emissions are reduced by approximately 70%. Most importantly, very similar performance was obtained with significant variations in intake temperature, proving the reliability and adaptability of this combustion concept. [ABSTRACT FROM AUTHOR]

The measurement of in-cylinder heat transfer can be a valuable diagnostic tool for quantifying and improving IC engine performance. Increased heat transfer out of the combustion chamber negatively impacts overall efficiency, while heat transfer from the metal to the charge can increase knock propensity. The heat flux at various locations in an engine cylinder can be measured using heat flux probes consisting of two thermocouples – a surface thermocouple exposed to the changing in-cylinder temperatures, and a far field thermocouple which has a constant temperature at steady state operating conditions. The buildup of carbon deposits on the surface thermocouple can affect the heat flux measurements and lead to errors in the data. Heat flux measurements were performed on a proprietary single-cylinder research engine with instrumented heat flux probes in the cylinder head and cylinder liner. The engine was run rich with a high PMI fuel to expedite the buildup of carbon deposits. A metric was developed based on the output of the surface thermocouple to determine the cleanliness of the heat flux probes non-intrusively. Heat flux calculations were done using the FFT method and validated using the Cook-Felderman method. An uncertainty analysis was conducted on the heat flux data to verify that the negative heat flux observed was not due to errors in the distance between the two thermocouples or the measurement of temperature. Finally, to bolster confidence in the results, heat flux measurements were made for motoring conditions with varying coolant and intake air temperatures to gauge whether the trends in the output were in the expected direction. [ABSTRACT FROM AUTHOR]

This paper deals with the performance improvement of a turbocharged spark ignition (SI) engine redesigned by adopting a refined 1D model and a rule-based (RB) calibration strategy. The new SI engine operates without the throttle valve and combines an early intake valve strategy with a two-stage compression ratio device. The resulting SI unit represents a promising short-term technical solution and it is also suitable as a flexible fuel engine.In a first phase, the engine model is validated with the experiments in the original configuration, and then it is virtually modified to obtain the redesigned solution. In this redesign process, the effects of the variations of engine geometry and valve strategy on combustion and performance are considered by phenomenological in-cylinder sub-models. Afterwards, the RB strategy is implemented into the re-designed engine model and assessed by comparing the results with the ones of an advanced calibration approach, based on an optimization with genetic algorithm performed by coupling the 1D model with an optimizer.The RB method replicates with acceptable accuracy the numerical trends of performance and control parameters of the SI engine coming from the optimizer. Once the capability is verified, the RB strategy is adopted to compute the steady operating map of the redesigned engine, with significantly less effort than an optimization. The map provides noticeable benefits in terms of full load torque, fuel consumption at medium-to-low loads and a slight extension of the minimum fuel consumption region. The combustion stability is maintained at acceptable levels, although it is improvable at very low loads and speeds. The presented methodology has a general validity for conventional SI engines and can be efficiently exploited to support the redesign stage of SI units for improved performance, with reduced computational effort. It also offers a method to rapidly compute the operating map of SI engines for subsequent on-vehicle analyses.

Evaluation of the effects of Gasoline-Methanol (GM) fuel blends on SI engine perfor-mance and emissions analysis was the aim of this research. Engine performance was ana-lyzed using M15 fuel blends at Wide Open Throttle (WOT) and various speed conditions between 1200 to 1800 rpm. A computerized 4s, 1cyl, VCR petrol engine test setup was used for the experimental work. The results found that the BSFC of M15 blends in-creased as much as regular gasoline for all engine speeds at full load. Exhaust emissions, including CO, HC, CO2, and NOx, are found to be minimized while engine torque and brake power (BP) is less than regular gasoline. This research recommends a methanol-gasoline blend can be an effective alternative for gasoline in transportation engines with-out requiring hardware modifications or causing major environmental harm. It found that the M15 fuel blend was appropriate for both increasing engine performance and reducing emissions. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of the dynamic parameters of a compact class passenger car powered by LPG/DME blends. The presented results are part of the research cycle of this vehicle, the purpose of which was to check the possibility of using DME (dimethyl ether) as an additive in the fuel mixture with LPG. In the presented part of the experimental research, the acceleration times of the vehicle under specific conditions were measured. On the basis of the obtained results, the relations between the average acceleration in the tested speed ranges, the fuel composition, and the degree of engine load were developed. The results of the analysis indicate that in the examined range of changes in the DME share in the fuel, comparable or higher acceleration values were obtained for all engine load levels. This confirms the usefulness of DME as a fuel component used to power SI engines. [ABSTRACT FROM AUTHOR]

Oxygen additional system was examined for CO2 capture system in gas fueled engine. In this study, the effect of the oxygen supply on combustion was investigated to increase CO2 concentration of the exhaust gas. As the amount of supplied oxygen increased, the more EGR was required for the higher thermal efficiency. Exhaust temperature increased as the amount of supplied oxygen increased under same G/F condition. The supplied oxygen could increase the CO2 concentration and the temperature of the exhaust gas.

Hydrogen fuel is gaining particular attention in internal combustion engines. In addition to zero-carbon emissions, major advantages relate to its combustion characteristics, which allow a significant increase in thermal efficiency under ultra-lean operation and with very low NOx levels. The ignition system is one of the main technology enablers, as it determines the capability to control ultra-lean operations, avoid backfire phenomena, and/or reduce the risks of abnormal combustions. The latter results from hydrogen's low ignition energy and it is associated with factors like high-temperature residuals, hot spots, and irregular spark plug discharge. The ACIS gen 2-Barrier Discharge Igniter excels in accelerating the initial flame growth speed by the generation of non-equilibrium low-temperature plasma, a strong ignition promoter for the combined action of kinetic and thermal effects. Moreover, its volumetric discharge facilitates combustion initiation on a wide region, in contrast to the localized ignition of traditional spark systems. In this work we present for the first time, to the best of our knowledge, experimental results showing the performance of a hydrogen engine with a low-temperature plasma discharge. Tests were conducted on a single-cylinder research engine, achieving ultra-lean conditions with cycle-to-cycle variability results below 2.5%. The analysis indicates that the H2-BDI combined solution is capable of accelerating the evolution of the flame front compared to traditional spark plugs, leading to a significant reduction in the cycle-to-cycle variability. A meticulous adjustment of the BDI control parameters further enhances igniter performance and contributes to a deeper understanding of the innovative approach proposed in this study. [ABSTRACT FROM AUTHOR]

Currently, conventional spark–ignition engines face challenges in meeting the ever-growing demands of customers and increasingly stringent regulations regarding pollutant emissions. A combination of innovative strategies and carbon-neutral fuels is deemed necessary in order to further reduce fuel consumption and minimize engine emissions. The present work aims to assess the performance of combustion strategies using low-carbon-content fuel, such as methanol M100, ignited by a plasma-assisted igniter (PAI) under ultra-lean conditions. The experimental campaign is conducted on a single-cylinder research engine at 1000 rpm and low loads, moving up to the engine lean stable limits. The specific purpose of this work is to determine the benefits brought by the proposed strategy, referred to as M100–PAI, which compared market gasoline E5 ignited by the PAI system and conventional spark. The synergy between M100 (methanol) and Plasma-Assisted Ignition (PAI) in internal combustion engines yielded notable benefits. This combination significantly improved combustion stability if compared to the other combinations tested, by extending the lean stable limit to λ = 2.0, reducing cycle-to-cycle variability, and facilitating faster flame front acceleration, resulting in enhanced homogeneity. These enhancements, obtained with the combination M100–PAI, contributed to higher fuel efficiency, showing a 10% efficiency gain over the combination E5–gasoline spark ignition. The findings highlight the potential of innovative combustion strategies using low-carbon fuels and advanced ignition systems to meet stringent emissions regulations while improving engine performance. [ABSTRACT FROM AUTHOR]

This study presents an experimental investigation into the impact of blending bioethanol (E100) with conventional gasoline (E0), incrementally increasing biofuel levels up to E10, E50, and E70. The test was carried out in two stages: Stage I assessed the engine's performance under fixed speeds (n = 2000 rpm and n = 2500 rpm) and fixed throttle positions (15%, 20%, and 25%) to measure changes in engine torque, efficiency, and environmental metrics by varying the concentration of bioethanol in the fuel. Stage II aimed to enrich the initial findings by conducting an additional test, running the engine at a fixed speed (n = 2000 rpm) and braking torque (MB = 80 Nm) and varying the ignition timing. Results indicated slight improvements in engine brake torque and thermal efficiency (up to 1.7%) with bioethanol content increased to 70%, and a notable reduction in incomplete combustion byproducts—carbon monoxide and hydrocarbons emissions (up 15% and 43%). Nitrogen oxide emissions were reduced by up to 23%, but carbon dioxide emissions decreased by a mere 1.1%. In order to increase thermal efficiency by adding higher bioethanol blend concentrations, adjusting the ignition timing to counter the longer ignition delay is necessary; however, higher emissions of nitrogen oxides and hydrocarbons are a major drawback of such a strategy. The results of the research are important in determining the optimal concentration of bioethanol in the mixture with gasoline for the energy and environmental sustainability of a spark ignition engine. [ABSTRACT FROM AUTHOR]

This article presents a study that compares the performance and emission characteristics of a four‐stroke, four‐cylinder spark ignition (SI) engine fueled by gasoline and neat hydrogen. The engine was equipped with turbocharging to optimize ignition timing for power boosting and vaporized water–methanol injection to reduce emissions. Engine tests were conducted at speeds ranging from 2000 to 6000 rpm, with a fixed intake pressure and varying quantities of hydrogen and spark advance timings. The study compared the results of non‐turbocharged and turbocharged engines with water–methanol injection in terms of combustion, performance, and emissions. The findings showed that the turbocharged water–methanol hydrogen operation had a higher brake thermal efficiency (BTE) than its counterpart, while the brake power of the hydrogen engine operation increased with turbocharging but slightly decreased with water–methanol injection. Additionally, volumetric efficiency improved by 7% for turbocharged and 4% for water‐injected hydrogen engine operation compared to the counterpart. The cylinder pressure for turbocharging with water–methanol operation yielded 16.32% higher compared with counterpart gasoline engine operation. Finally, nitrogen oxides (NOx) emissions were reduced with turbocharging and water–methanol injection compared to the counterpart non‐turbocharged hydrogen engine operation. [ABSTRACT FROM AUTHOR]

This paper aims to numerically investigate the effects of high compression ratio (CR) on the performance of ammonia-hydrogen engines. In this work, four CRs from 10.7 to 13.7 with scanning spark timing (ST) from 28°CA to 0°CA BTDC were analyzed. The main results are as follows: As the CR increases, there is a trade-off relationship between the dissipation rate of turbulence and the turbulent kinetic energy (TKE). Initially, the TKE rises as the CR increases. As the CR continues to rise, the tendency for an increase in TKE diminishes, while the turbulent dissipation rate consistently rises. Additionally, there is an escalation in heat transfer loss. Therefore, there is a trend of rising and then falling in the flow velocity and turbulence intensity with the increase of the CR. Ammonia-hydrogen flame propagation is susceptible to temperature and flow field, and a high CR can improve ignition stability, shorten combustion duration, minimize cooling loss, and enhance output power. Unfortunately, the emission of NOx gradually rises as the CR increases. At high CR, the combustion performance is optimized by adjusting ST, and the maximum IMEP and ITE are 4 bar and 38.3 %, respectively. The ST for maximum braking torque (MBT) should be gradually delayed toward TDC as the CR increases. • As the compression ratio increases, the flow velocity first rises and then decreases. • The turbulent dissipation rate increases with increasing compression ratio. • A high compression ratio improves ignition stability and combustion velocity. • The NOx gradually increases with the increase of the compression ratio. • A high compression ratio improves the power and economy of NH3-H2 engines. [ABSTRACT FROM AUTHOR]

Current dynamics of world energy supply have driven various innovations by the industry as well as research communities. Fossil fuels, although experiencing a declining interest due to sustainability issues, remain undeniably crucial since they are nearly irreplaceable in some sectors including electricity generation, it is necessary to continuously establish efforts to improve efficiency of those kinds of fuel. In this work, the authors evaluate the potential of locally sourced essential oils, namely citronella, as a fuel additive in a vision of raising the fuel economy of gasoline RON 90. Citronella oil was selected based on a positive hypothesis deduced from its chemical properties, as mentioned in multiple published works. Tests were made on a generator-set powered by gasoline engine using the mixture of RON 90 and citronella oil of various concentrations as the fuels. In addition, a commercial synthetic additive was also tested alongside the essential oil to provide a comparative figure. Meanwhile other investigators suggest a favorable effect of essential oils, our results show that citronella oil additions lead to higher fuel consumption at the same power level. A similar negative effect was also demonstrated by the synthetic additive. The only sector showing positive results is in terms of exhaust temperature where experiments with citronella additives create lower exhaust temperature as compared to pure gasoline and synthetic additives. However, rooms for innovation remain open by exploring other variables such as higher additive concentrations or combining different kinds of essential oils.

This study focuses on the combustion timing control in hydrogen mixed combustion of a spark ignition gas engine. Especially, we examined the effect of hydrogen mixed ratio and air excess ratio on the combustion feature under same engine conditions. The 50% mass fraction burning timing (MFB50T) is within the specified range under MBT condition, independent of hydrogen mixed ratio and air excess ratio. We also examined the combustion phase estimation method using the existing sensor of the engine. The MFB50T can be estimated by the peak timing of angle speed.

In the current study, an onboard dry cell electrolyzer was built to produce an oxyhydrogen (HHO) flow rate of 0.5 L/min by water electrolysis. The objective is to show the impact of oxyhydrogen introduction on engine exhaust gases, combustion characteristics, and engine performance related to gasoline. The experiments were carried out in a petrol engine at a fixed engine speed of 3000 rpm and variable engine loading. When comparing HHO gasoline dual fuel to standard gasoline fuel, the maximum improvements in volumetric efficiency, thermal efficiency and air-fuel ratio were determined as 7.5%, 8% and 11%, respectively. In the case of HHO addition, the highest reductions in specific fuel consumption and exhaust gas temperature were 9% and 6.5%, respectively, compared with conventional gasoline fuel. The highest reduction in CO, HC, NOx, and CO 2 concentrations was observed as 18%, 9%, 15%, and 11%, respectively, for HHO-gasoline dual-fuel mode compared to gasoline fuel. The peak cylinder pressure and HRR improvements were 1.5% and 4.5%, respectively, at 100% engine load. Oxyhydrogen gas is highly recommended as a substitute fuel since it significantly enhances engine performance and combustion characteristics as well as reducing exhaust pollutants. • An on-board dry cell electrolyzer was used with an HHO flow rate of 0.5 L/min. • Experiments were carried out in SI engine at 3000 rpm and variable engine loading. • Maximum improvement in BTE was 8% about the reduction in BSFC was 9%. • HHO-gasoline dual-fuel mode found reduction in CO, HC, NOx, and CO 2 emission. [ABSTRACT FROM AUTHOR]

An ethanol-fueled Atkinson cycle PFI SI engine using exhaust rebreathing (ER) was evaluated under 110 different operating conditions. While ethanol is an important biofuel to reduce greenhouse gas emissions, Atkinson cycle engines have been studied as low-consumption alternatives for hybrid architecture vehicles. The operating conditions were validated with GT-Power® and the resulting combustion and performance parameters were trained by a series of artificial neural network (ANN) structures in order to learn and reproduce the non-linear correlations. The ANN structures were analyzed by number of nodes, hidden layers, and optimization methods. TPA results showed that ER tests had higher indicated thermal efficiency and lower combustion temperatures than both the standard Atkinson cycle and Otto cycle conventional throttled valve strategy with a similar engine setup. The best ANN to accurately predict all six outputs with easy-to-measure operating conditions was a combined ANN-PSO model, with two hidden layers with [30 10] nodes to predict net IMEP, airflow, total mass trapped and burned mass percentage, and a complementary 10-nodes PSO hidden layer, to predict PMEP, and the average exhaust runner temperature. The final model can predict and calibrate an Atkinson cycle PFI SI engine operating with ER with significant accuracy and no need for further TPA simulations. [ABSTRACT FROM AUTHOR]

Considering the gradual reduction of fossil fuel resources and their role in environmental issues, biodiesel-derived products have received much attention as fuel additives to enhance their properties and reduce emissions. The present work reports the engine performance and emission characteristics for a fuel blend consisting of solketal, a derivative of glycerol and gasoline. In this study, 5–10 vol% solketal was mixed with gasoline by ultrasonic processor to prepare a solketal-gasoline fuel blend. The blending of additives will affect the volumetric transport properties as well as the combustion quality of the fuel. Some important properties like thermal conductivity, surface tension, adiabatic compressibility, relative association, and intermolecular free path length were measured at different temperatures by measuring the ultrasonic velocity in the fuel blend. Four-stroke SI engine performance was studied in terms of brake-specific fuel consumption (BSFC) and brake thermal efficiency (BTE). BSFC increases by 15%, and BTE shows a marginal reduction of about 5.39% at 28.13 N·m torque with a 10% solketal-gasoline blend. The exhaust analysis indicates that CO emissions decrease and NOx and CO2 increase compared to pure gasoline as fuel, the brake thermal efficiency indicates a marginal reduction of about 5.39% for 10% solketal. [ABSTRACT FROM AUTHOR]

In the present experimental study hydrogen-assisted ammonia combustion strategy is used in a SI engine with variable ignition timings (18ºCA bTDC to 32ºCA bTDC) and wide-open throttle conditions, CR changes (14–16) at 1400RPM and 1800RPM. This article aims to optimize ignition timing to boost efficiency and power without knocking. It has been established that ammonia/hydrogen fuels are a clean energy source capable of reducing pollution caused by undesirable emissions. The results revealed that increasing the CR from 14 to 16 increased brake power, brake thermal efficiency, NO X , cylinder pressure, and net heat release rate by 36.82%, 25.11%, 30.21%, 10.35%, and 9.53%, respectively. CA10-90 and EGT, on the other hand, are reduced. Increased speed reduces volumetric efficiency by 9.5% at 1800 RPM. In each CR, 28ºCA bTDC ignition timing and 21% hydrogen energy fraction performed well, which can be observed. Hence, the experiment results indicate hydrogen can be used as a combustion promoter, establishing a new standard for developing ammonia-fuelled engines. • Study of dual fuelled ammonia/hydrogen SI engine is very effective. • At 28ºCA bTDC, the addition of H 2 increases the BP and BTE without causing knock. • There are no greenhouse gas emissions, hence there is no impact on global warming. • The influence of thermal NOx and fuel NOx on overall NOx emissions. [ABSTRACT FROM AUTHOR]

Renewable resources are minimal throughout the world and considerable research work has been carried out to develop fossil-based options. Aim of the research work is to evaluate performance and engine exhaust emissions of varying blends at different conditions in engine. The experiments are conducted to analyze the performance of three distinct gasoline-alcohol fuel mixtures EM25 (10 percent ethanol-15 percent methanol-75 percent gasoline) in a computerized 1-cylinder, 4-stroke, VCR SI engine. The additional tests are conducted using regular gasoline fuel to compare performance and engine exhaust emissions. The engine performance using mixed fuel of ethanol-methanol-gasoline (GEM) has been evaluated under the various operating conditions in the range of 1200 to 1800 rpm, Spark Timings (ST's) 100, Air Fuel Ratio 0.9 at constant Compression Ratio (CR) 10:1. When the vehicles operated with ethanol-methanol-gasoline mixtures then it has found that there is the reduction in HC, CO2, CO exhaust gases contents while 14% increments in NOx emission as compared with regular gasoline fuel. It is also observed that the brake power/brake torque is decreased when operated on ethanol-methanol-gasoline fuels as compared to pure gasoline. However, it has been revealed that BSFC is enhanced in comparison to regular gasoline. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical evaluation of the pre-chamber induced HCCI combustion concept (PC-HCCI) in terms of engine performance, emissions, and controllability. In this concept, a spark-initiated combustion in the pre-chamber is utilized to trigger the kinetically controlled combustion of an ultra-lean mixture in the main combustion chamber. The experimental measurements were performed on a single-cylinder engine with a custom-made active pre-chamber. A high compression ratio of 17.5 was used, which limits the maximum achievable engine load due to high knocking tendency but enables both standard PCSI combustion (flame propagation) at very high dilution levels and HCCI combustion at reasonable intake temperatures. The analysis of combustion characteristics and the resulting performance is performed at indicated mean effective pressures (IMEPs) of 3.5 and 3.0 bars, and three different intake temperatures of 80 °C, 90 °C, and 100 °C. The variation in engine load was achieved by adjusting the excess air ratio in the main chamber. On each combination of intake temperature and engine load, a spark sweep and an injected PC fuel mass sweep were performed to obtain the highest indicated efficiency while satisfying the restrictions in terms of combustion stability and knock intensity. It was shown that, unlike in a conventional HCCI engine, the combustion phasing can be directly and reliably controlled by adjusting either spark timing or the reactivity of the pre-chamber mixture, ensuring adequate combustion stability and eliminating potential misfires. A similar indicated efficiency as with conventional HCCI combustion was obtained, while the NOx emissions, although slightly elevated, are still insignificant. Compared to PCSI combustion at the same engine load, a 4-percentage-point increase in indicated efficiency and two times lower NOx emissions were achieved. Compared to the most efficient PCSI operating point, it was 1 percentage point lower, indicating that efficiency was achieved, but the specific NOx emissions are reduced by approximately 70%. Most importantly, very similar performance was obtained with significant variations in intake temperature, proving the reliability and adaptability of this combustion concept.

An engine modelling study was conducted to investigate the relative change in performance and emissions of a 4-stroke, spark-ignition engine using Iraqi Associated Petroleum Gas as fuel. The research was done using a well-verified simulation software Diesel-RK. The data available for Ricardo E6/T variable compression ratio spark-ignition engine was used to conduct this study. The performance of the engine using associated petroleum gas was compared with those for gasoline, natural gas, and the average properties of the natural gas in Europe. The performance parameters studied were engine power, thermal efficiency, oxides of nitrogen, unburned hydrocarbon, and carbon monoxide levels. The study showed that the Iraqi associated petroleum gas could not be used "as is" if the aim is to cut down pollution. The main advantage is the absence of sulfur in the gas, which is present in the gasoline used in Iraq. There is a significant rise in NOx levels, a reduction in UHC, and also a rise in CO levels when using APG fuel. Further, there is an average reduction in engine power of about 10% with the associated gas compared with gasoline. At the same time, the only gain is the reduction in SFC and improvement in thermal efficiency with the new fuel. [ABSTRACT FROM AUTHOR]

The global requirement is shifting to territorial independence of energy sources, and the introduction of alcohols and biofuels are the primary sectors. Recently agriculture products-based ethanol has replaced a larger portion of gasoline. Butanol is another impressive fuel in the same chain, much better than ethanol in many parameters. Butanol has certain limitations, too, such as higher latent heat and low heating value. Therefore, biobutanol/hydrogen is tested experimentally at various compression ratios (CR) in the present study. Brake thermal efficiency was not significantly changed by CR at 90% butanol, while CR is more impressive with increasing hydrogen. The flame development period was reduced by 34%, while the flame propagation phase was reduced by 29% by increasing CR to 15 and hydrogen to 25%. Peak pressure and heat release rate surged by 12.89% and 12.32% and advanced by 6°CA. The coefficient of variations is also reduced by 21% by increasing CR to 15 and hydrogen to 30%. Higher hydrogen faced combustion difficulties due to increasing stratification and heterogeneity during combustion. Unlikely to trend, T max (peak cylinder temperature) and NO x were continuously increased with CR and hydrogen due to increased fuel quantity and larger mass burning before TDC. However, CO and HC emissions were reduced by CR due to increased BTE (brake thermal efficiency) and reduced by hydrogen due to less HC supply. A slight increase in HC and CO was noticed for higher hydrogen due to local heterogeneity and disassociation at high temperatures. • Biobutanol faces less difficulty in combustion at elevated CR. • Biobutanol/Hydrogen at 75/25 combination improves engine performance. • CoV imep was low for all combination, least for 75/25 B/H fuel. • Net carbon emissions reduce with hydrogen induction but NO x increased. • At high CR biobutanol and hydrogen are complementary. [ABSTRACT FROM AUTHOR]

Acetone–gasoline fuel is one potential favorable alternative option to regular gasoline fuel. This work attempts to mitigate pollution while simultaneously improving SI engine performance with acetone (AC) proportion in fuel mixture and varying engine speed. Acetone–gasoline alternative fuel was experimentally prepared by mixing 5–10 vol.% of acetone into ordinary gasoline. The experiments were performed in a spark ignition (SI) single-cylinder, four-stroke at variable engine speed. The engine performance was measured by an eddy current dynamometer (ECD), while the exhaust engine was measured by a gas analyzer connected to the gasoline engine. The proposed strategy, the integrated combined polynomial regression with whale optimization algorithm (WOA), was implemented. The results showed that the acetone blending of 10 % with gasoline (AC10: 10 vol. % acetone + 90 vol. % gasoline) decreases carbon monoxide (CO), unburned hydrocarbon (UHC), and nitrogen oxides (NOx), emissions by 26.3%, 30.3%, and 6.6%, respectively. Furthermore, the AC10 exhibited better engine brake power (BP) than pure gasoline, with an improvement of 4.39%. According to the optimization results, the BP was enhanced by AC10 to record 2.426 kW at 2887 rpm. In addition, engine emissions reduced to the lowest levels of 142.849 ppm, 0.426%, and 1088.178 ppm, in terms of UHC, CO, and NOx, respectively. The experiment results show that the WOA optimizer can accurately predict the optimal point in SI engine performance and emissions.

In this study, the effect of different intake manifold geometries on the performance of a spark-ignited engine is investigated both numerically and experimentally. 1D and 1D-3D simulations are carried out to find the optimal dimensions of different intake manifold designs. The numerical simulations are successfully validated with real data. The results show that the manifold design utilizing two-valve throttle has a better performance. The superior design is constructed and mounted on the engine to compare the output result with the base design. The operation tests are performed at various rotational speeds in the range of 1000-6000 rpm. Regarding the experimental tests, the superior double intake manifold increases the engine brake power and torque by 6.814%.

Bio-n-butanol is widely recognized as a renewable alternative biomass fuel, it is gradually used in internal combustion engines for scientific research to alleviate the energy crisis and environmental pollution. However, due to the difference of physical and chemical properties between n-butanol and gasoline, if n-butanol is directly applied to gasoline engines, it will certainly cause changes in engine performance. Therefore, it is of great significance to explore the optimal energy conservation potential of n-butanol application in gasoline engines. Driven by this fact, an experiment was conducted in a high speed, spark ignition (SI) engine with n-butanol blended ratio of 0% and 35% by volume to gasoline, and simulation model of GT-Power coupling with MATLAB/Simulink is built and calibrated based on the tested data. The synergistic optimization of multiple operating variables with the corresponding genetic algorithms (GA) optimization methodologies is carried out to reveal the optimal energy conservation potential of engine fueled with butanol–gasoline blends. Results show that, when the torque remains the same with respect to that of the original engine, the optimized brake specific energy consumption (BSEC) at the corresponding engine speed under full load are significantly lower than the original BSEC, the average improvement in percentage of BSEC is approximately 7.11%. By adopting the method of multi-objective genetic algorithm (MOGA), the power and economy of the engine fueled with butanol–gasoline blends can be balanced simultaneously. The engine operating parameters can be chosen that the BSEC may be small while the engine is optimally powered. Besides, it is found that the pumping loss is affected by the combined effect of intake timing and exhaust timing. The optimization procedure can be applied to calibrate the universal characteristics of engines, and the findings obtained from this study can provide guidance for better application of alternative energy in traditional thermal machines.

This work shows the results of an experimental campaign carried out in two spark ignition engines, a small optical research engine and its commercial counterpart, using a turbulent ignition system (pre-chamber) specifically designed for small engines. Advanced optical techniques and conventional methods were used to study the combustion process under various operating conditions. The pre-chamber operated actively in the research engine and passively in the commercial engine. Results showed that the pre-chamber configuration resulted in an increase in indicated mean effective pressure (IMEP) and a decrease in the coefficient of variation (CoV) of IMEP. These improvements compensated for challenges such as slow methane combustion rate, poor lean burn capability, and air displacement. In addition, the pre-chamber configuration exhibited lower fuel consumption and specific exhaust emissions compared to the standard ignition system. The novelty of this work lies in the successful implementation of the turbulent ignition system as a retrofit solution for SI engines, showing improved combustion efficiency and lower emissions. The study goes beyond previous efforts by demonstrating the benefits of the pre-chamber configuration in small engines without requiring extensive modifications. The results provide valuable insights into the automotive industry's pursuit of engine optimization and highlight the significance of innovative approaches for spark ignition engines in contributing to sustainable mobility. [ABSTRACT FROM AUTHOR]

The paper presents the results of tests on a SI engine fueled with an LPG/DME blends of various composition. A number of experimental studies and calculations using a mathematical model were carried out to examine the suitability of this fuel. These tests allowed for the analysis of the changes taking place in the combustion process and the assessment of the main operating parameters of the engine. The engine was powered by an LPG/DME fuel mixture with different proportions of components. The share of DME ranged from 0% to 30% of the fuel mass. The obtained results reflect the operation of the engine in the full load range and selected rotational speeds. Measurement series were made for different settings of the ignition advance angle. Based on the obtained results, a corrected map of the ignition advance angle was developed. The obtained results confirm the usefulness of using the LPG/DME mixture to power the SI engine. [ABSTRACT FROM AUTHOR]

Compressed natural gas (CNG) has gained popularity due to its wide availability, higher efficiency, and lower emissions compared to gasoline. However, the lower flame speed characteristics of CNG with conventional port injection reduce the CNG engine volumetric efficiency and power output. CNG's lower gas jet momentum during a low load operation creates a non-uniform air-fuel mixture that affects ignition and combustion quality. Direct injection of CNG with optimum injection timing is expected to improve volumetric efficiency, ignition quality, and combustion process. In this study, a comparative study on the effect of end-of-injection (EOI) timing on volumetric efficiency, thermal efficiency, combustion duration, and emissions was carried out in a single-cylinder port fuel injection (PFI) spark-ignition engine using gasoline and CNG, and direct injection (DI) spark ignition engine using CNG. The experiments were performed at two-part load operations of 20% and 40% throttle at 900 and 1500 rpm. Experimental results indicate that the PFI CNG engine is more influential in EOI timing than gasoline engines. The performance of the PFI CNG engine is improved when the injection occurs during the intake valve open period compared to the closed valve period with higher thermal efficiency, volumetric efficiency, and indicated mean effective power (IMEP). A shorter flame development angle and combustion duration were observed when EOI timing was in the open intake valve condition. DI CNG improved volumetric efficiency at advanced EOI timing compared to the PFI CNG engine. However, the combustion process is critically dependent on injection timing and air-fuel mixing duration. A three-dimensional computational fluid dynamics simulation was conducted to evaluate the effect of advanced and retarded EOI timing on DI CNG engine's in-cylinder turbulent kinetic energy development and in-cylinder equivalence ratio near the ignition point. An excess advanced EOI timing resulted in stratified rich and retarded EOI timing results in loss of turbulence energy, leading to a slightly rich and lean mixture for advanced and retarded EOI timing, respectively. Hence, an optimum EOI timing provides a conducive environment to initiate the combustion and flame front propagation. Further, advanced EOI timing was required at higher throttle opening and engine speed. The emissions in DI CNG were also greatly affected by EOI timing. [ABSTRACT FROM AUTHOR]

A systematic analysis of knocking combustion at the knock limit in a single-cylinder research engine is conducted. Both experimental and numerical methods are used to investigate the physical phenomena involved in knocking combustion. While real gasoline fuel can be used directly in experimental studies, this is not feasible in numerical simulations. Here, surrogate fuels with a reduced number of components defined to match the desired properties, such as knock resistance, are employed. In this work, standard gasoline and three surrogate fuels are considered. Differences in composition complexity are covered by selecting isooctane and two toluene reference fuels (TRF) with ethanol addition, all of which exhibit negative temperature coefficient (NTC) behavior in which auto-ignition delay times increase with increasing temperature. Spark timing sweeps at two engine speeds show that the knock resistance of the fuels correlates with the respective research octane number (RON). Isooctane is found to have higher knock resistance and higher sensitivity to engine speed than standard gasoline. One of the two TRFs studied shows good agreement with gasoline in terms of combustion and knock characteristics. The lower knock resistance of the other TRF indicates a non-linear dependence between mixture composition and knock resistance. A strong relative increase in knock resistance at higher engine speeds suggests a possible influence of NTC behavior at lower engine speeds. In the subsequent model-based analysis, the fuel influence on combustion and auto-ignition is investigated, and the laminar burning velocities are found to correlate well with the observed heat durations. While auto-ignition may be triggered by a cool spot at the lower engine speed and at operating conditions within the NTC regime, auto-ignition at the higher engine speed is assumed to be initiated by hot spots. These different mechanisms for initiating auto-ignition were identified as a potential explanation for the different knock resistances observed. [ABSTRACT FROM AUTHOR]

The transportation sector is the main consumer for liquid fuel in many countries, fuel quality is the main indicator for efficient engine operation. Hence, the current study aims to investigate the utilization of Methyl Tert-Butyl Ether (MTBE) as an octane booster with local low octane gasoline at an addition ratio of 5%, 10%, and 15% on a volume basis in addition to pure local gasoline. The coefficient of variation has been calculated at a constant operation condition of 4000 rpm engine speed and 50% Wide Open Throttle (WOT). The results reveal that the lower engine BP obtained with local gasoline (50.65 kW) and increased with adding MTBE by about 4.3 for GMTBE10 compared to local gasoline and the lower BSFC found to be 267.4 g/kW h for GMTBE5. Accordingly, the higher BTE obtained for MTBE 10 and found to be 32%. A delay of CA50 was observed with local gasoline compared to other fuel samples with MTBE additive. On the other hand, the lower COVIMEP obtained with GMTBE10 indicates the most stable engine operation. Accordingly, GMTBE10 gives better engine performance and stable operation among the tested fuel samples and can be considered as the best ratio for MTBE with local gasoline. [ABSTRACT FROM AUTHOR]

Growing environmental concerns over global warming and depleting fossil fuel reserves are compelling researchers to investigate green fuels such as alcoholic fuels that not only show the concrete decrement in emissions but also enhance engine performance. The current study emphasizes the influence of different alcoholic fuel blends in gasoline on engine performance and emissions for an engine speed ranging from 1200 to 4400 rpm. The obtained performance results demonstrate that the brake power and brake thermal efficiency (BTE) increased with an incrementing blend percentage of ethanol and methanol in gasoline (EM). The minimum brake specific fuel consumption (BSFC) was ascertained using pure gasoline followed by E2 and then E5M5. The NOx and CO2 emissions can be described in the decreasing order of E, EM and gasoline due to same trend of exhaust gas temperature (EGT). CO results were in reverse order of CO2. HC emissions were found in the increasing order of E, EM and pure gasoline. E10 performed better among all blends in terms of less exhaust emissions and engine performance. However, EM blended with gasoline significantly reduced NOx. E5M5 produced 1.9% lower NOx emission compared to E10 owing to 1.2% lower EGT. Moreover, greenhouse gases such as CO2, which is mainly responsible for global warming reducing by 1.1% in case E5M5 as compared to E10. [ABSTRACT FROM AUTHOR]