Mixed Fuels Research Articles

Modeling and Numerical Investigations of Flowing N-Decane Partial Catalytic Steam Reforming at Supercritical Pressure

Steam reforming is an effective method for improving heat sinks of hypersonic aircraft at high flight Mach numbers. However, unlike the industrial process of producing hydrogen with a high water content, the catalytic steam reforming mechanism for the regeneration cooling process of hydrocarbon fuels with a water content below 30% is still unclear. Catalytic steam reforming (CSR) and catalytic thermal cracking (CTC) reactions occur at low temperatures, with the main products being hydrogen and carbon oxides. Thermal cracking (TC) reactions occur at high temperatures, with the main products being alkanes and alkenes. The above reaction exists simultaneously in the regeneration cooling channel, which is referred to as partial catalytic steam reforming (PCSR). Based on the experimental measurement results, an improved neural network correction method was used to establish a four-step global reaction model for the PCSR of n-decane under low water conditions. The reliability of the four-step model was verified by combining the model with a numerical simulation program and comparing it with the experimental results obtained by electric heating hydrocarbon fuels with a pressure of 3 MPa and a water content of 5/10/15%. The experimental and predicted results using the developed kinetic model are consistent with an error of less than 5% in the decane conversion rate. The average absolute error between the fuel outlet temperature and total heat sink is less than 10%. Using the PCSR model to predict the heat transfer characteristics of mixed fuels with different water contents, the convective heat transfer coefficient is basically the same, and the Nu number is affected by the thermal conductivity coefficient, showing different patterns with changes in the water content.

U-Net Semantic Segmentation-Based Calorific Value Estimation of Straw Multifuels for Combined Heat and Power Generation Processes

This paper proposes a system for real-time estimation of the calorific value of mixed straw fuels based on an improved U-Net semantic segmentation model. This system aims to address the uncertainty in heat and power generation per unit time in combined heat and power generation (CHPG) systems caused by fluctuations in the calorific value of straw fuels. The system integrates an industrial camera, moisture detector, and quality sensors to capture images of the multi-fuel straw. It applies the improved U-Net segmentation network for semantic segmentation of the images, accurately calculating the proportion of each type of straw. The improved U-Net network introduces a self-attention mechanism in the skip connections of the final layer of the encoder, replacing traditional convolutions by depthwise separable convolutions, as well as replacing the traditional convolutional bottleneck layers with Transformer encoder. These changes ensure that the model achieves high segmentation accuracy and strong generalization capability while maintaining good real-time performance. The semantic segmentation results of the straw images are used to calculate the proportions of different types of straw and, combined with moisture content and quality data, the calorific value of the mixed fuel is estimated in real time based on the elemental composition of each straw type. Validation using images captured from an actual thermal power plant shows that, under the same conditions, the proposed model has only a 0.2% decrease in accuracy compared to the traditional U-Net segmentation network, while the number of parameters is significantly reduced by 74%, and inference speed is improved 23%.

Unraveling the Nanosheet Zeolite-Catalyzed Combustion of Aluminum Nanoparticles-Doped exo-Tetrahydrodicyclopentadiene (JP-10) Energetic Fuel.

Nanosheet MFI zeolites (Zeolite Socony Mobil, five) have grown in popularity in cracking catalysis considering their tunability in porous topologies, acidic sites, and sheet thickness, thus allowing them to selectively adsorb molecules of specific sizes, shapes, and polarities, resulting in improved cracking performance for a specific fuel. Five different MFI zeolites in the form of a mesoporous nanosheet structure with a controlled concentration of acidic sites denoted as NSMFI(y), where y is Si/Al ratio, have been synthesized. The effects of the relative acidity content of these NSMFI(y) samples on the zeolite-catalyzed combustion of aluminum nanoparticles (AlNPs)-aided exo-tetrahydrodicyclopentadiene (JP-10) mixed energetic fuel droplets levitated in an oxygen-argon atmosphere were investigated using time-resolved imaging (optical and thermal infrared) and spectroscopic techniques (UV-vis and FTIR). The addition of 1.0 wt % of NSMFI(y) zeolites to AlNPs-JP-10 fluid fuel results in critically reduced ignition delays (9 ± 2 ms), elevated ignition temperatures (2800 ± 170 K), and prolonged burning times (60 ± 10 ms) with an enhanced combustion efficiency. The NSMFI(y) zeolites, which possess high acidity and significant mesoporosity, play a crucial role in improving the combustion efficiency by effectively catalyzing the chemical activation of JP-10 and prolonging the burning of the igniting droplet. The NSMFI (60) variant with the highest acidic site content achieved a maximum combustion efficiency of 80 ± 6%. A comprehensive catalytic combustion mechanism has been elucidated based on the detected reactive intermediates such as hydroxyl radical (OH) and aluminum monoxide (AlO). These findings will help to critically advance the development of next-generation, sustainable, and innovative mixed nanofluid fuels.

Investigating the Characteristics of Injecting and Spraying Methanol-Containing Fuel in a Diesel Engine

Introduction. The operation of eco friendly and high-efficiency internal combustion engines is not possible without deep and comprehensive study of using new types of fuels. That is why, forecasting the indicators of injecting and spraying in a diesel engine running on a mixed alcohol-containing fuel, which have a direct effect on the combustion and formation of toxic components and, as a result, on efficiency and eco friendliness, is an urgent scientific task.Aim of the Study. The study is aimed at developing a theoretical basis for calculating the characteristics of injecting and spraying methanol-containing fuel into diesel engine cylinders that allows optimizing its processes.Materials and Methods. There are considered the characteristics of injecting and spraying alcohol-containing fuel in a diesel engine modified to operate on a mixed methanol-containing fuel. There were used the well-known A.S. Lyshevsky dependencies, which fairly reliably reflect the processes of injecting and spraying in diesel engines.Results. The in-depth studies of the basic principles for evaluating the indicators of injecting and spraying standard fuel made it possible to adapt them for fuels of mixed methanol-containing composition and to investigate the dynamics of changes in the duration and speed of injection, the Weber criterion values, the boundaries between the areas of fuel jet forming, droplet size and spraying angle.Discussion and Conclusion. There has been developed a theoretical basis for calcu­lating the characteristics of injecting and spraying methanol-containing fuel that makes it possible to optimize the operation of a diesel engine running on mixed fuel and, as a result, improve its efficiency and eco friendliness. The presented numerically information on the change in the boundaries of the fuel jet forming areas, the size of the droplets and the angle of the spraying cone allows us to reliably determine the basic parameters of spraying of the used mixed methanol-containing fuels, determine the vector of optimization of the mixing processes and gives insight into the promising directions in designing the geometry of combustion chambers, intake ducts, etc.

Research of the processes of ignition and combustion of mixed fuels based on coal and wood under different conditions of thermal influence

The ignition processes of mixed fuels formed on the basis of grade 3B coal from the Maikuben deposit and finely dispersed sawmill and woodworking waste have been studied. An analysis of the processes of ignition and combustion of fuel mixtures with different organization of combustion processes was performed. It has been established that the concentration of the wood component has a significant impact on the processes of the onset of oxidation and combustion of mixed fuels. When the proportion of wood component in the mixture increases to 50%, the ignition delay time decreases by an average of 18% in all cases of the studies performed.

Drivers of variation in fuel choice for cooking: From the selected towns of North Shoa, Oromia Regional State, Ethiopia

This study aimed to examine household fuel choice behaviour and drivers of variation in fuel choice for cooking. It utilizes descriptive statistics, ordered logit model and generalized ordered logit model to analyze the influence of independent variables upon dependent variables. The result shows that, mixed fuels are the dominant sources of energy with 43.75 % followed by unclean fuel with 33.25 % and then clean fuel with 23 %. This confirms ‘households’ Fuel-Stacking behaviour. The result of the ordered logit model suggest that variables like family size, per monthly income, the gender of household head, household ownership of electric meter, ownership of housing unit, marital status, age, occupation, educational levels of household heads, and the number of the adult females are statistically significant at 1 %, 5 %, and 10 % while, place of residence and occupation (self-non agriculture) are statistically insignificant to determine fuel choice. Identifying the fuels which are chosen by households should serve as a guide for government and policymakers in the formulation and implementation of policies and strategies that will guarantee optimal access to clean energy sources. Therefore, the government should improve the supply and distribution of electric meters by subsidizing them.

Fuel mixing and diffusion behind the unswept ramp injector with lobed nozzle at combustor of scramjet engine

-The use of 2-lobe nozzle for efficient fuel mixing behind the ramp injector nozzle is comprehensively investigated in this article. Computational fluid dynamic is applied for the evaluation of the three-dimensional flow behind the strut with annular 2-lobe nozzle at supersonic combustion chamber. In this work, the Mach number of free steam air flow and fuel jet are 2 and 1, respectively. The usage of internal air jet for the fuel mixing improvement is also analyzed to disclose the critical features which improve the fuel diffusion in the combustor. The Mach contour on the horizontal and vertical planes in both injection model is compared to show how induced vortex pair is created and extended behind the strut. The result of computational study shows that the injection of the air jet increases the number of vortex pairs behind the strut and the interaction of the fuel with air jet is increased. However, the circulation strength is decreased by inner air jet. Use of inner jet enhances the fuel mixing more than two times behind the nozzle. Our findings show that the fuel mixing is heightened downstream of strut by coupling inner air jet with annular fuel jet.

Characterization of Waste Biomass Fuel Prepared from Coffee and Tea Production: Its Properties, Combustion, and Emissions

In order to reduce global warming, new energy fuels that use waste biomass to replace traditional coal are rapidly developing. The main purpose of this study is to investigate the feasibility behavior of different biomass materials such as spent coffee grounds (SCGs) and spent tea grounds (STGs) as fuel during combustion and their impact on the environment. This study involves using fuel shaping and co-firing methods to increase the fuel calorific value and reduce the emissions of pollutants, such as NOX and SO2, and greenhouse gas CO2. The produced gas content was analyzed using the HORIBA (PG-250) laboratory combustion apparatus. The results indicate that, among the measured formed particles, SCG:STG = 8:2, 6:4, and 4:6 had the lowest post-combustion pollutant gas emissions. Compared to using only waste coffee grounds as fuel, the NOx emissions were reduced from 166 ppm to 102 ppm, the CO emissions were reduced from 22 ppm to 12 ppm, and the CO2 emissions were reduced from 629 ppm to 323 ppm. In addition, the emission of SO2, the main component of acid rain, was reduced by 20 times compared to the combustion of traditional fuels. The SO2 emission of five different proportions of biomass fuels was 5 ppm, which is much lower than that of traditional coal fuels. Therefore, SCG and STG mixed fuels can replace coal as fuel while reducing harmful gasses.

Experimental Study of Natural Gas and Hydrogen Co-Firing Characteristics Using Different Types of Single Nozzles of F-Class Practical Gas Turbine Combustors

Abstract Recent research on co-firing natural gas and hydrogen, a carbon-free clean fuel, aims to reduce greenhouse gas emissions from aging gas turbine power generation, a key energy issue. This approach can enhance old gas turbines and increase the proportion of combined cycle power plant utilization as coal-fired power plants in Korea gradually shut down. This study seeks optimal operating conditions for mixed fuels without modifying the F-class gas turbine combustor. Experiments were conducted using four different types of fuel nozzles (F-Class DLN combustors) under varying loads and co-firing rates. The test used actual machine operating conditions from 30% to 100% thermal load, with hydrogen co-fired with natural gas up to 70% at each load. OH high-speed imaging and an OH-PLIF technique analyzed flame structure and characteristics. Dynamic pressure was measured to check combustion instability, and exhaust gas emissions were evaluated for combustion characteristics. Key findings include critical co-firing rates for each nozzle based on NOx emission levels and combustion dynamics. As the hydrogen co-firing rate increased, flame length decreased, and NOx levels rose rapidly beyond 30%vol. Dynamic pressure oscillations showed no significant variations compared to natural gas combustion. This study successfully derived a characteristic operation map for a single nozzle based on the hydrogen co-firing rate.

The changing mix of fossil fuels used and the related evolution of CO2 emissions

To limit global climate change, ultimately it will be necessary to minimize the use of all fossil fuels for energy. Because the rate of CO2 emissions per unit of primary energy varies among the fossil fuels, it is useful to focus first on reducing the use of coal, the fuel with the most CO2 per unit of energy used. Although multiple factors are involved in the choice of which fuel will be used for a given purpose, data on CO2 emissions show that over the last 25 years there has been an evolution in the fraction of emissions away from coal and toward natural gas. That is, although total emissions have continued to increase globally, the fraction attributable to coal has been decreasing in many places. This is true for the global sum of emissions, for Annex I countries, and for all regions except Asia Pacific. The fraction of emissions from oil products has varied largely with growth in the contribution of petroleum transportation fuels. Focus on decreasing the sum of all fossil fuels is needed, especially among the major energy users in the Asia Pacific region, but progress in the decreasing relative use of coal is promising.

Experimental and numerical study on the influence of N2/H2 on the laminar combustion characteristics of syngas premixed flames

This paper primarily analyzes the influence of N2 and H2 content on the laminar combustion characteristics of low calorific value syngas, using a constant-volume combustion bomb to measure the laminar combustion velocity (SL) of the fuel and compare it with five commonly used mechanisms. The study reveals that higher N2 content significantly reduces the SL of CO/CH4/CO2 mixed fuels, primarily due to a general decrease in the mole fractions of key intermediates and net reaction rates. Increasing H2 content leads to an increase in the SL of CO/CH4/CO2/N2 mixed fuels. The thermal effect becomes increasingly prominent with the elevation of H2 content, while the proportion of thermal effect initially decreases and subsequently increases as the equivalence ratio rises. With the increase in N2 content, the mole fraction of NO experiences a significant decrease, and the rate of decline in thermal NO production is even faster. Conversely, with the increase in H2 content, the rate of rise in non-thermal NO generation is faster, and the mole fraction of NO tends to increase.

Методологічні основи визначення і контролю витрат біопалив у процесі руху автомобіля

The paper proposes a methodological approach to determine and control fuel consumption (biofuels) of a car that has known design parameters and moves in known conditions at known modes. It is noted that at this stage it is more attractive to use mixed fuels based on gasoline or diesel fuel with the addition of various impurities of biological origin. For gasoline-based fuels, impurities can be methyl or ethyl alcohol, for diesel fuel – vegetable oils, as well as their methyl and ethyl esters of these oils. A structural and logical scheme has been developed, which explains the main provisions of the proposed determining method and controlling the biofuels consumption. In the structural and logical scheme, the following groups of parameters that take place during the car movement are highlighted: parameters of the conditions, the driving mode design. The mutual influence of parameters among themselves and between groups, the influence of the biological component concentration on its consumption, which must be taken into account to determine and control the consumption of biofuels during the movement of the car, was analyzed. It is shown that when switching to the use of biofuel, there is a change in the indicator coefficient of the internal combustion engine, which also affects the change in consumption.It has been proven that in the process of using biofuel, important factors affecting its consumption are density, lower heat of combustion, and the theoretically required amount of air for kg of biofuel combustion, which depends on the volumetric a specific biological component concentration in it. It has been proven that in the biofuel use process, important factors affecting its consumption are density, lower heat of combustion and the theoretically necessary amount of air for combustion in 1 kg of biofuel, which depends on the volumetric a specific biological component concentration. Taking into account the relative indicators of the «main» fuel (lower combustion heat, density and theoretically necessary air amount for the combustion of 1 kg impurities), it was established that the smallest increase in fuel consumption by the car engine during operation occurs when rapeseed oil is added to diesel fuel.

Study on thermal behavior and gas pollutant emission control during the co-combustion of rice straw-modified oily sludge and coal

Oily sludge (OS) is a solid waste generated from oil industry activities that can threaten the ecological environment and human health if not properly treated or disposed of. In this paper, the thermal behavior and emission of gas products during the co-combustion of rice straw (R) modified OS (OS5-R5) and coal (C) were investigated using an automatic calorimeter and model analysis. The effect of combustion atmosphere and additives on the gas products emission during the co-combustion of C, R, OS5-R5, and mixed fuels were investigated. The results show that as the content of OS5-R5 increased in mixed fuels, the performance of mixed fuels worsened gradually. When the mass content of OS5-R5 is 30 %, the lower heating value (LHV) was about 20 MJ/kg, which is about 16 % lower than that of C, but the comprehensive combustion index had no significant decrease. The additives could control the emission of pollutant gases. The increase of heating rate from 5 °C/min to 20 °C/min resulted in an increase of the overall combustion performance of the mixed fuel by 5.07-time. Similarly, increasing the oxygen concentration from 10 % to 100 % led to a 3.09-time increase in the combustion index of the mixed fuel. The adsorption of polar molecules by montmorillonite was conducive to reducing the emission of pollutant gases. BaO and CaO do not affect NO and NO2 emission control but reduce H2S and SO2 emissions because BaO and CaO could react with H2S and SO2 to form sulfate resulting in reduced emission. The research provides a theoretical basis for OS's safe disposal and efficient resource utilization.

The fuel property and application prospect of water-containing biofuel from Clostridium acetobutylicum fermentation products

Biobutanol, a promising green alternative fuel, fermented from Clostridium acetobutylicum, while its high-cost and limited yield constraining its development. ABE (acetone-butanol-ethanol) and IBE (isopropanol-butanol-ethanol) are mixed fermentation products from non-edible biomass raw materials, using them together with water as alternative fuels will reduce industrial production costs and save fossil fuels. Therefore, this study conducted a multifaceted experimental evaluation on ABE/IBE mixed fuels with different water content, demonstrating that it has good water holding capacity when mixed with traditional fossil fuels. Taking ABE (3: 6: 1) as an example, its water holding capacity after mixing with diesel at 10–90 % is 0.37–7.83 % at 20 °C. Meanwhile, the particle size of ABE/IBE mixed fuels is about 2–30 nm, exhibiting a microemulsion with thermodynamic stability. The anhydrous or water-containing mixed fuel with the ratio of ABE (IBE) of 10%–50 % meets the range of the density and kinematic viscosity of diesel engine fuel. The mixed fuel is non-corrosive to copper without water, and a water content of about 3 % or higher will increase the risk of engine corrosion at 20 °C. Despite the addition of biofuel and water, studies on energy combustion performance and pollutant emission performance have found that appropriate addition of biofuel and water can produce higher power output and lower pollutant emissions than traditional fossil fuels, with ABE20W0.5 being the optimal. This study demonstrates the great potential of ABE and IBE as biofuels to achieve carbon neutrality goals, providing novel research direction for green alternative fuels in the future.

Research on the Mechanism and Propagation Characteristics of Combustion and Explosion of Natural Gas/Ammonia/Hydrogen Mixed Gas Fuel.

The addition of ammonia and hydrogen into natural gas fuel is an effective method to reduce carbon emissions. This study aims to investigate the effect of adding ammonia and hydrogen on the mechanism of natural gas combustion and emission characteristics. Based on a self-developed mixed gas deflagrate experimental platform, the deflagrate characteristics, emission characteristics, and chemical reaction kinetics mechanism of mixed gas fuels under different composition ratios (natural gas 0-100%, hydrogen 10-85%, and ammonia 0-100%) were studied. The results indicate that the propagation of the deflagration shock wave can be categorized into an initial stage (L < 3 m) and a development stage (L > 3 m) based on the observed trend of shock wave intensity variation with distance. The intensity of the deflagration shock wave for the mixed gases increases monotonically as the hydrogen content ratio rises. In contrast, the impact of the ammonia content ratio on the shock wave intensity exhibits a distinct pattern that varies with changes in the equivalence ratio and hydrogen content ratio. In terms of carbon emissions per unit of heat value produced by the fuel, adding hydrogen to natural gas proves to be more effective at reducing carbon emissions than adding ammonia. When the ammonia content ratio is 50% and the hydrogen content ratio is 40%, the combustion performance of the mixed gas fuel is similar to that of natural gas, but its carbon emissions are lower than 30% of natural gas, making it a new type of mixed fuel with potential application value; the interaction between reflected pressure waves and flames is the main reason for the fluctuation of deflagrate shock wave pressure; ammonia lowers the temperature of the reaction system by reducing the concentration of OH radicals.

Influence of Incident Shock on Fuel Mixing in Scramjet

During the operation of hypersonic vehicles, a reciprocal coupling effect is manifested between the inlet and the combustion chamber. This results in an unavoidable non-uniformity of conditions at the combustion chamber’s entrance, which, in turn, influences the fuel mixing within the chamber. The present study employed the Reynolds-averaged Navier–Stokes (RANS) equations to perform a numerical simulation of an X-51-like vehicle, with a focus on examining the impact of isolation section length and multi-injection strategies on the fuel mixing characteristics within the combustion chamber under conditions of non-uniform inflow. The findings indicated that a supersonic non-uniform inlet triggers incident shock waves, leading to a non-uniform pressure distribution across the flow section. Moreover, the position of injection was found to be pivotal in regulating penetration depth and mixing efficiency. The incident shock wave, bow shock, and boundary layer separation shock interacted with each other to increase local pressure. The coupling of high and low pressures generated an adverse pressure gradient that led to boundary layer separation, which further enhanced fuel penetration depth.

Environmental Emissions Performance for Energy Transition in Cement Industrial Sector from Natural Gas to Energy Fuel Mix Case Study: Cement Company in Egypt

Environmental Emissions Performance for Energy Transition in Cement Industrial Sector from Natural Gas to Energy Fuel Mix Case Study: Cement Company in Egypt

Boiler Performance with Variations in Fuel Mix Composition Feeding

PKS Kertajaya is a subsidiary of PTPN VIII, which focuses on the palm oil industry. a number of main processing and supporting equipment for this factory. One of the key aspects of the production process is the use of the boiler. This equipment produces steam, which is needed by various palm oil production processes and even factory utility areas. Therefore, the research study focused on the quantity of fuel used in producing the steam. The palm oil industry utilizes the solid waste from fresh fruit bunches, namely fibers and shells. The variable variation is in the percentage of the two fuels. From the estimation results using the direct method, it was found that the feeding conditions of 50:50, 60:40, and 70:30% were able to provide an increase in boiler efficiency values along with decreasing operational fuel costs. However, if you compare it with the quantity of fuel that has been applied by the industry, the percentage of 50:50% is the optimum condition, both in terms of boiler efficiency and economic value, which is one level higher than the current condition. This consideration is viewed from the estimation side as well as the amount of carbon content owned. Apart from that, the palm oil industry continues to maintain performance during routine maintenance of boiler equipment. Ingredients other than carbon are able to make short- to long-term contributions to producing steam. PKS Kertajaya merupakan anak perusahaan PTPN VIII yang berfokus di bidang industri kelapa sawit. Dari sejumlah peralatan utama proses maupun pendukung pabrik ini. Ssalah satu aspek kunci proses produksinya berada pada penggunaan boiler. Peralatan ini menghasilkan uap air yang dibutuhkan ragam proses produksi minyak kelapa sawit bahkan area utilitas pabrik. Oleh karena itu, kajian penelitian difokuskan ke kuantitas bahan bakar yang digunakan dalam memproduksi steam tersebut. Pihak industri kelapa sawit memanfaatkan peran limbah padat dari tandan buah segar, yaitu serabut dan cangkang. Variasi variabel berada pada persentase kedua bahan bakar tersebut. Dari hasil estimasi melalui penggunaan metode langsung didapatkan bahwa kondisi pengumpanan 50:50, 60:40, dan 70:30% mampu memberikan peningkatan nilai efisiensi boiler dengan seiring menurunnya biaya operasional bahan bakar. Akan tetapi, jika membandingkan dengan kuantitas bahan bakar yang telah diterapkan pihak industri maka persentase 50:50% adalah kondisi optimum baik sisi efisiensi boiler dan nilai ekonomi yang lebih tinggi satu tingkat dari kondisi saat ini. Pertimbangan ini ditinjau dari sisi estimasi dan juga jumlah kandungan karbon yang dimiliki. Selain itu, pihak industri kelapa sawit tetap menjaga performa selama terutama pelaksanaan perawatan rutin peralatan boiler. Kandungan selain karbon mampu memberikan kontribusi baik jangka pendek hingga panjang dalam memproduksi uap air.

An experimental study on enhancing performance and reducing emissions of CRDI engine operated on Co-pyrolysis oil using particle swarm optimization

This study explores the use of Artificial Neural Network and Particle Swarm Optimization to improve the performance and emissions of a CRDI engine fuelled by a mixture of co-pyrolyzed oil and diesel. Experimental results show that the mixed fuels perform better than pure diesel in various engine conditions, achieving higher brake thermal efficiency and lower smoke emissions. The blend D90P10 has the highest BTE of 37.4% working at FIT 30°bTDC and FIP 500 bar. However, NO and CO2 emissions were increased for the same condition. A multi-parametric ANN model is created to build a predictive model based on this experimental data, relating inputs (fuel injection pressure, fuel injection timing, and blend percentages) to outputs (Brake Specific Fuel Consumption, NO, smoke, CO2 emissions). The ANN model attains high accuracy with R2 values of 0.99, 0.98, 0.99, and 0.99 for BSFC, NO, Smoke, and CO2 emission predictions, respectively. The results indicate that for optimal performance, the best conditions are a FIT of 29.71ºbTDC, a FIP of 500 bar, and a co-pyrolysis oil blend percentage of 19.61%. On the other hand, to minimize engine emissions, the best conditions are FIT of 20.28ºbTDC, FIP of 300 bars, and a blend percentage of 25.6%. A balanced approach results in an optimal condition of FIT at 29.5ºbTDC, FIP of 500 bars, and a blend percentage of 6.11%. Experimental validation of these optimal predictions shows a maximum error of only 3.18%, highlighting the reliability and accuracy of the model.

Prediction of emission characteristics of diesel/n-hexanol/graphene oxide blended fuels based on fast outlier detection-sparrow search algorithm-bidirectional recurrent neural network

This study aims to utilize deep learning (DL) technology to address the issue of carbon soot emission in traditional internal combustion engines. Spraying and combustion experiments were conducted in a constant volume combustion (CVC) chamber using n-hexanol and graphene oxide nanoparticles as partial substitutes for diesel, with the goal of predicting their emission characteristics based on experimental data. Initially, spray and combustion data under different operating conditions were collected using the CVC experimental setup, and outliers were removed using the fast outlier detection (FOD) algorithm. Subsequently, the learning rate and the number of hidden layer neurons in the Bidirectional Recurrent Neural Network (BiRNN) model were optimized using the Sparrow Search Algorithm (SSA) to enhance the model's accuracy and generalization ability. Unlike previous research methods, the novel FOD-coupled SSA optimization method used in this study ensures the optimal parameter configuration of the speed prediction model while accelerating the convergence speed, which ultimately improves the stability of the model. In addition, the optimal output variables were determined based on the Spearman and Pearson correlation coefficient rules. Finally, the effectiveness of the predictive model was validated using evaluation metrics such as root mean square error (RMSE) and R-squared (R2). The results indicate that the KL coefficient for D80H20GO20 fuel in the CVC device is minimal. The FOD-SSA-BiRNN model achieved R2 values of 0.99409, 0.99529, and 0.99692 for D100, D80H20, and D80H20GO20 fuels, respectively. Therefore, this study provides an effective method for the online accurate prediction of carbon soot emissions in mixed fuels.