Pub Date : 2025-02-19DOI: 10.1016/j.fuel.2025.134719
Amir A. Beige, Amir Mardani
<div><div>Reducing fuel consumption and chemical pollutions is considered as a crucial issue, as many applications still depend on fossil fuels. In this paper, large eddy simulations of a gas turbine model combustor (GTMC) are performed in both normal and diluted/preheated conditions to have a better understanding of MILD combustion in these combustors. For this purpose, the flame structures are studied using the graphical and statistical tools, and the accuracy of the simulations is assessed by comparing the time-averaged results to the available experimental data. To model the turbulent combustion, Eddy Dissipation Concept (EDC) method is used with DRM-22 reduced mechanism in addition to the Wall-Adapting Local Eddy-Viscosity (WALE) turbulence model. To simulate the MILD combustion conditions, about 36 % reduction in fuel flow rate, 32 % dilution of the oxidizer (by EGR), in addition to preheating air to 730 K are used in the investigated diluted/preheated case. It is shown that the dilution/preheating of the incoming air creates stronger vortices (due to higher inlet velocities), faster mixings, and lower rates of H-atom abstraction (also due to lower fuel flow rates) in the upstream parts of the reactant jet, which is shown effective in expanding the radicals of the diluted/preheated flame. Moreover, it is observed that dilution/preheating reduces HO2 formation rates (and consequently weakens H2O2 routes) in upstream parts of the reactant jet, and also increases the rate of both chain branching and recombination reactions. Investigation of negative heat release spots reveals that their strength shows an almost linear relation with Q-criterion in the regions dominated by vorticity and they also appear closer to the positive heat release spots in the diluted/preheated mode. Furthermore, a generalized autoignition index is proposed based on the HO2 kinetics and it is used to illustrate the flame propagation and autoigntion regions for the investigated flames, which shows the spatial expansion of reaction spots in the diluted/preheated combustion mode and small role of auto-ignition spots in overall heat release for both flames. The CH2O dynamics also shows more distributed ignition for the diluted/preheated case in addition to the appearance of intermittent strong CH2O spots for both flames. Furthermore, the statistical analysis reveals less dependence of the ignition process on velocity gradients in the diluted/preheated mode. It is shown that while the rate of kinetically slower elementary reactions drops sharply in high strain regions of the normal combustion case, the rate of these reactions are less affected in the diluted/preheated mode. Consequently, some of the OH producing reactions are inhibited in high strain regions of the conventional combustion case, which causes the flame of this case to be stabilized outside of the high strain zones. Remarkably, while the positive heat release spots of the diluted/preheated flame are observed to
{"title":"Large Eddy simulation of dilution and preheating impacts on chemical aspects of flame stabilization in a gas turbine model combustor","authors":"Amir A. Beige, Amir Mardani","doi":"10.1016/j.fuel.2025.134719","DOIUrl":"10.1016/j.fuel.2025.134719","url":null,"abstract":"<div><div>Reducing fuel consumption and chemical pollutions is considered as a crucial issue, as many applications still depend on fossil fuels. In this paper, large eddy simulations of a gas turbine model combustor (GTMC) are performed in both normal and diluted/preheated conditions to have a better understanding of MILD combustion in these combustors. For this purpose, the flame structures are studied using the graphical and statistical tools, and the accuracy of the simulations is assessed by comparing the time-averaged results to the available experimental data. To model the turbulent combustion, Eddy Dissipation Concept (EDC) method is used with DRM-22 reduced mechanism in addition to the Wall-Adapting Local Eddy-Viscosity (WALE) turbulence model. To simulate the MILD combustion conditions, about 36 % reduction in fuel flow rate, 32 % dilution of the oxidizer (by EGR), in addition to preheating air to 730 K are used in the investigated diluted/preheated case. It is shown that the dilution/preheating of the incoming air creates stronger vortices (due to higher inlet velocities), faster mixings, and lower rates of H-atom abstraction (also due to lower fuel flow rates) in the upstream parts of the reactant jet, which is shown effective in expanding the radicals of the diluted/preheated flame. Moreover, it is observed that dilution/preheating reduces HO2 formation rates (and consequently weakens H2O2 routes) in upstream parts of the reactant jet, and also increases the rate of both chain branching and recombination reactions. Investigation of negative heat release spots reveals that their strength shows an almost linear relation with Q-criterion in the regions dominated by vorticity and they also appear closer to the positive heat release spots in the diluted/preheated mode. Furthermore, a generalized autoignition index is proposed based on the HO2 kinetics and it is used to illustrate the flame propagation and autoigntion regions for the investigated flames, which shows the spatial expansion of reaction spots in the diluted/preheated combustion mode and small role of auto-ignition spots in overall heat release for both flames. The CH2O dynamics also shows more distributed ignition for the diluted/preheated case in addition to the appearance of intermittent strong CH2O spots for both flames. Furthermore, the statistical analysis reveals less dependence of the ignition process on velocity gradients in the diluted/preheated mode. It is shown that while the rate of kinetically slower elementary reactions drops sharply in high strain regions of the normal combustion case, the rate of these reactions are less affected in the diluted/preheated mode. Consequently, some of the OH producing reactions are inhibited in high strain regions of the conventional combustion case, which causes the flame of this case to be stabilized outside of the high strain zones. Remarkably, while the positive heat release spots of the diluted/preheated flame are observed to ","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134719"},"PeriodicalIF":6.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.fuel.2025.134682
Salauddin Al Azad , Meysam Madadi , Ashfaque Rahman , Chihe Sun , Fubao Sun
The conversion of sugarcane bagasse (SCB) into fermentable sugars via pretreatment and enzymatic hydrolysis is a promising pathway for biomass valorization. However, the process’s complexity and variable optimization have limited its efficiency. This study introduces an orthogonal experimental design (OED) combined with machine learning (ML) to optimize NaOH-catalyzed Triton-X 100 pretreatment and enzymatic hydrolysis. The optimal pretreatment conditions identified through rule-based ML modeling (100 g/L solid loading, 45 g/L NaOH, 13.8 pH, 200 mL Triton-X 100, 175 °C, and 45 min) resulted in cellulose and hemicellulose recoveries of 88.5 % and 81.8 %, respectively, and a delignification of 92.3 %. The relative errors from experimental validation were 1.42 %, 0.56 %, and 3.55 % for these metrics, respectively. In the enzymatic hydrolysis (50 g/L substrate loading, 6 FPU/g enzyme loading, and 72 h hydrolysis), glucose and xylose yields reached 84.3 % and 63.3 %, with relative experimental validation errors of 1.11 % and 2.26 %, respectively. Key factors included time (26.2 % contribution to cellulose recovery), temperature (37.5 % to hemicellulose recovery), and solid loading (19.6 % to delignification). Substrate loading contributed 45.7 % to glucose and 37.8 % to xylose yields. This ML-optimized approach is projected to generate an additional US$321.45 million in profits by 2025, increasing to US$494.39 million by 2030, while reducing SCB waste by approximately 45 %. These findings highlight the potential of ML to enhance biomass conversion efficiency and accelerate the industrial adoption of bio-based sugar production systems.
{"title":"Machine learning-driven optimization of pretreatment and enzymatic hydrolysis of sugarcane bagasse: Analytical insights for industrial scale-up","authors":"Salauddin Al Azad , Meysam Madadi , Ashfaque Rahman , Chihe Sun , Fubao Sun","doi":"10.1016/j.fuel.2025.134682","DOIUrl":"10.1016/j.fuel.2025.134682","url":null,"abstract":"<div><div>The conversion of sugarcane bagasse (SCB) into fermentable sugars via pretreatment and enzymatic hydrolysis is a promising pathway for biomass valorization. However, the process’s complexity and variable optimization have limited its efficiency. This study introduces an orthogonal experimental design (OED) combined with machine learning (ML) to optimize NaOH-catalyzed Triton-X 100 pretreatment and enzymatic hydrolysis. The optimal pretreatment conditions identified through rule-based ML modeling (100 g/L solid loading, 45 g/L NaOH, 13.8 pH, 200 mL Triton-X 100, 175 °C, and 45 min) resulted in cellulose and hemicellulose recoveries of 88.5 % and 81.8 %, respectively, and a delignification of 92.3 %. The relative errors from experimental validation were 1.42 %, 0.56 %, and 3.55 % for these metrics, respectively. In the enzymatic hydrolysis (50 g/L substrate loading, 6 FPU/g enzyme loading, and 72 h hydrolysis), glucose and xylose yields reached 84.3 % and 63.3 %, with relative experimental validation errors of 1.11 % and 2.26 %, respectively. Key factors included time (26.2 % contribution to cellulose recovery), temperature (37.5 % to hemicellulose recovery), and solid loading (19.6 % to delignification). Substrate loading contributed 45.7 % to glucose and 37.8 % to xylose yields. This ML-optimized approach is projected to generate an additional US$321.45 million in profits by 2025, increasing to US$494.39 million by 2030, while reducing SCB waste by approximately 45 %. These findings highlight the potential of ML to enhance biomass conversion efficiency and accelerate the industrial adoption of bio-based sugar production systems.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134682"},"PeriodicalIF":6.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.fuel.2025.134669
Amsini Sadiki , Yaquan Sun
Focusing on liquid jet in crossflow (LJICF) systems, two different liquid fuels (Jet A and Gasoline) are examined to analyze the effects of two different crossflow temperatures on a chain of four consecutive physical processes (atomization-evaporation, spray dispersion, turbulence-evaporation interaction, and turbulent mixing). For this purpose, a novel approach that integrates phase change within a seamless coupling of the Volume of Fluid (VOF) method and Lagrangian Particle Tracking (LPT) approach within a Large Eddy Simulation framework is developed and applied. Thereby, Adaptive Mesh Refinement (AMR) is integrated to dynamically refine the liquid–gas interface while allowing for reducing computational costs. The phase change is considered at both the gas–liquid interface in VOF and the dispersed Lagrangian droplets. The atomization process is analyzed in terms of instabilities, breakup modes and penetration length. The atomization-evaporation interaction is pointed out through the impact of temperature on the breakup monitored by means of a breakup regime diagram. The induced turbulence-evaporation interaction is measured by an evaporation Damköler number introduced in this paper. The increasing evaporation Damköhler number with streamwise distance indicates a transition from turbulence-dominated to evaporation-dominated behavior, highlighting improved evaporation rates and mixing efficiency at higher temperatures. Evaporation enhances turbulent kinetic energy and mixing, particularly for Gasoline, while also affecting vortex dynamics. The resulting turbulent mixing is retrieved by appropriate turbulent mixing indices. Comparisons of flow visualization, penetration length, droplet statistics and total liquid mass flux with available experimental data agree well confirming the predictive capability and reliability of the developed approach.
{"title":"Effect chain of fuel disintegration of liquid fuel jet evaporating in hot crossflow","authors":"Amsini Sadiki , Yaquan Sun","doi":"10.1016/j.fuel.2025.134669","DOIUrl":"10.1016/j.fuel.2025.134669","url":null,"abstract":"<div><div>Focusing on liquid jet in crossflow (LJICF) systems, two different liquid fuels (Jet A and Gasoline) are examined to analyze the effects of two different crossflow temperatures on a chain of four consecutive physical processes (atomization-evaporation, spray dispersion, turbulence-evaporation interaction, and turbulent mixing). For this purpose, a novel approach that integrates phase change within a seamless coupling of the Volume of Fluid (VOF) method and Lagrangian Particle Tracking (LPT) approach within a Large Eddy Simulation framework is developed and applied. Thereby, Adaptive Mesh Refinement (AMR) is integrated to dynamically refine the liquid–gas interface while allowing for reducing computational costs. The phase change is considered at both the gas–liquid interface in VOF and the dispersed Lagrangian droplets. The atomization process is analyzed in terms of instabilities, breakup modes and penetration length. The atomization-evaporation interaction is pointed out through the impact of temperature on the breakup monitored by means of a breakup regime diagram. The induced turbulence-evaporation interaction is measured by an evaporation Damköler number introduced in this paper. The increasing evaporation Damköhler number with streamwise distance indicates a transition from turbulence-dominated to evaporation-dominated behavior, highlighting improved evaporation rates and mixing efficiency at higher temperatures. Evaporation enhances turbulent kinetic energy and mixing, particularly for Gasoline, while also affecting vortex dynamics. The resulting turbulent mixing is retrieved by appropriate turbulent mixing indices. Comparisons of flow visualization, penetration length, droplet statistics and total liquid mass flux with available experimental data agree well confirming the predictive capability and reliability of the developed approach.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134669"},"PeriodicalIF":6.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.fuel.2025.134769
Hangwei Wan, Qi Zhang, Yuquan Wen, Cheng Wang
The outward dispersion of solid medium with heat source properties is a common form in explosion accidents. If the liquid fuel leaks to form a cloud, it may explode again when encountering an ignition source. However, the relative motion between the high-temperature source and the combustible cloud makes the explosion process complicated. The 20L cylindrical explosion vessel was used to study the non-premixed and premixed PO cloud explosion by experimental and simulation methods. The relationship between the peak pressure of cloud explosion and mass concentration is an inverted ‘U’ under two ignition modes, and the maximum explosion pressure under non-premixed ignition is higher than that under premixed ignition. The time to reach the peak pressure of non-premixed cloud explosion is obviously advanced at higher temperatures, while it has little effect on the explosion time of premixed cloud. For non-premixed cloud ignition, a liquid fuel can be ignited by a high-temperature source during the dispersion process at a lower spray pressure. The variation range of peak pressure in liquid cloud explosion is more intense than that of initial spray pressure. We hope that this study can provide a basis for the prevention of liquid fuel explosion accidents.
{"title":"Explosion characteristics of non-premixed cloud in relative motion between heat source and flowing cloud","authors":"Hangwei Wan, Qi Zhang, Yuquan Wen, Cheng Wang","doi":"10.1016/j.fuel.2025.134769","DOIUrl":"10.1016/j.fuel.2025.134769","url":null,"abstract":"<div><div>The outward dispersion of solid medium with heat source properties is a common form in explosion accidents. If the liquid fuel leaks to form a cloud, it may explode again when encountering an ignition source. However, the relative motion between the high-temperature source and the combustible cloud makes the explosion process complicated. The 20L cylindrical explosion vessel was used to study the non-premixed and premixed PO cloud explosion by experimental and simulation methods. The relationship between the peak pressure of cloud explosion and mass concentration is an inverted ‘U’ under two ignition modes, and the maximum explosion pressure under non-premixed ignition is higher than that under premixed ignition. The time to reach the peak pressure of non-premixed cloud explosion is obviously advanced at higher temperatures, while it has little effect on the explosion time of premixed cloud. For non-premixed cloud ignition, a liquid fuel can be ignited by a high-temperature source during the dispersion process at a lower spray pressure. The variation range of peak pressure in liquid cloud explosion is more intense than that of initial spray pressure. We hope that this study can provide a basis for the prevention of liquid fuel explosion accidents.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134769"},"PeriodicalIF":6.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.fuel.2025.134725
Usame Demir , Halil Erdi Gülcan , Salih Özer
The vehicles used in the aviation sector are widely employed in both transportation and industrial fields, and the energy requirements of these tools are currently met with fossil-based fuels. Reducing the consumption of these fossil fuels could contribute to mitigating environmental and economic impacts. Nanoparticle additives can be used in fossil-derived fuels to reduce fuel consumption. In this study, the effects of adding different proportions of TiO2 nanoparticles to kerosene (Jet A1) fuel in a jet engine are examined from the perspectives of performance, emissions, energy, exergy, and environmental-economic impacts. The experiments are conducted with three different test fuels (Jet A1, Jet A1+100 ppm TiO2, and Jet A1+200 ppm TiO2) and at nine different engine speeds (from 40 k rpm to 120 k rpm in increments of 10 k rpm). The results demonstrate that the use of TiO2 (200 ppm) in Jet A1 fuel reduced specific fuel consumption by an average of 16 % and decreased HC, CO, and CO2 emissions by average percentages of 18 %, 17 %, and 10 %, respectively. Additionally, the exergy efficiencies of the compressor, combustion chamber, and gas turbine systems were found to increase with TiO2 usage. Moreover, the addition of TiO2 to Jet A1 fuel showed the potential to reduce enviroeconomic impact by up to 10 %. In conclusion, it can be stated that the use of TiO2 in Jet A1 fuel is beneficial for reducing fuel consumption, enhancing exergetic efficiency, and improving enviroeconomic sustainability of jet engines used in both industrial and transportation sectors.
{"title":"The effect of TiO2 nanoadditive on emissions, exergetic performance, and enviro/social/economic indicators in a small UAV jet engine fuelled with kerosene","authors":"Usame Demir , Halil Erdi Gülcan , Salih Özer","doi":"10.1016/j.fuel.2025.134725","DOIUrl":"10.1016/j.fuel.2025.134725","url":null,"abstract":"<div><div>The vehicles used in the aviation sector are widely employed in both transportation and industrial fields, and the energy requirements of these tools are currently met with fossil-based fuels. Reducing the consumption of these fossil fuels could contribute to mitigating environmental and economic impacts. Nanoparticle additives can be used in fossil-derived fuels to reduce fuel consumption. In this study, the effects of adding different proportions of TiO<sub>2</sub> nanoparticles to kerosene (Jet A1) fuel in a jet engine are examined from the perspectives of performance, emissions, energy, exergy, and environmental-economic impacts. The experiments are conducted with three different test fuels (Jet A1, Jet A1+100 ppm TiO<sub>2</sub>, and Jet A1+200 ppm TiO<sub>2</sub>) and at nine different engine speeds (from 40 k rpm to 120 k rpm in increments of 10 k rpm). The results demonstrate that the use of TiO<sub>2</sub> (200 ppm) in Jet A1 fuel reduced specific fuel consumption by an average of 16 % and decreased HC, CO, and CO<sub>2</sub> emissions by average percentages of 18 %, 17 %, and 10 %, respectively. Additionally, the exergy efficiencies of the compressor, combustion chamber, and gas turbine systems were found to increase with TiO<sub>2</sub> usage. Moreover, the addition of TiO<sub>2</sub> to Jet A1 fuel showed the potential to reduce enviroeconomic impact by up to 10 %. In conclusion, it can be stated that the use of TiO<sub>2</sub> in Jet A1 fuel is beneficial for reducing fuel consumption, enhancing exergetic efficiency, and improving enviroeconomic sustainability of jet engines used in both industrial and transportation sectors.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134725"},"PeriodicalIF":6.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.fuel.2025.134765
Sen Tian , Huimin Jia , Zhaolong Ge , Guangjin Wang , Ruyi Bai
With the large-scale exploitation of shale gas resources, there are more and more shale gas wells with pressure exhaustion and even abandonment in low pressure reservoirs. However, these shale gas wells are rich in resources and still have great exploitation potential and utilization value. On this basis, the basic physical parameters of typical shale minerals (montmorillonite, calcite, and illite), such as pore structure, were investigated through carrying out low temperature nitrogen test based on field research and mineral composition tests. Meanwhile, by performing the volumetric method adsorption experiment, the competitive adsorption behavioral characteristics of minerals under the conditions of temperature at 70–130℃, pressure at 0–6 MPa and different gas mixture ratios of CH4/CO2 were studied. In addition, the key influencing factors and rules of the competitive adsorption of typical shale minerals under the high temperature and low pressure conditions were revealed. The results showed that under the experimental conditions, the lower temperature and the higher pressure led to the larger adsorption capacities of three minerals, and the growth rate of adsorption capacity gradually slowed down with the increase in pressure. To be specific, the order of minerals adsorption capacity montmorillonite > calcite > illite, proved that the larger mineral specific surface area resulted in the larger pore volume, the better pore structure development, and the superior adsorption performance. At the optimal adsorption effect (70℃, 6 MPa, 75 %CO2 + 25 %CH4), the adsorption capacity of montmorillonite was 0.381 mmol/g, while that of illite was 0.085 mmol/g, and that of calcite was 0.164 mmol/g. Because carbon dioxide occupied most of the adsorption sites and spaces on the surfaces of the three minerals during their competitive adsorption, carbon dioxide had stronger competitive adsorption performance. The results in this study prove to a certain extent that under the low pressure and high temperature conditions, increasing the carbon dioxide concentration is more conducive to shale gas displacement, so as to improve the shale gas recovery rate.
{"title":"Experimental study on the CH4/CO2 competitive adsorption behaviors of typical shale minerals in low pressure reservoirs","authors":"Sen Tian , Huimin Jia , Zhaolong Ge , Guangjin Wang , Ruyi Bai","doi":"10.1016/j.fuel.2025.134765","DOIUrl":"10.1016/j.fuel.2025.134765","url":null,"abstract":"<div><div>With the large-scale exploitation of shale gas resources, there are more and more shale gas wells with pressure exhaustion and even abandonment in low pressure reservoirs. However, these shale gas wells are rich in resources and still have great exploitation potential and utilization value. On this basis, the basic physical parameters of typical shale minerals (montmorillonite, calcite, and illite), such as pore structure, were investigated through carrying out low temperature nitrogen test based on field research and mineral composition tests. Meanwhile, by performing the volumetric method adsorption experiment, the competitive adsorption behavioral characteristics of minerals under the conditions of temperature at 70–130℃, pressure at 0–6 MPa and different gas mixture ratios of CH<sub>4</sub>/CO<sub>2</sub> were studied. In addition, the key influencing factors and rules of the competitive adsorption of typical shale minerals under the high temperature and low pressure conditions were revealed. The results showed that under the experimental conditions, the lower temperature and the higher pressure led to the larger adsorption capacities of three minerals, and the growth rate of adsorption capacity gradually slowed down with the increase in pressure. To be specific, the order of minerals adsorption capacity montmorillonite > calcite > illite, proved that the larger mineral specific surface area resulted in the larger pore volume, the better pore structure development, and the superior adsorption performance. At the optimal adsorption effect (70℃, 6 MPa, 75 %CO<sub>2</sub> + 25 %CH<sub>4</sub>), the adsorption capacity of montmorillonite was 0.381 mmol/g, while that of illite was 0.085 mmol/g, and that of calcite was 0.164 mmol/g. Because carbon dioxide occupied most of the adsorption sites and spaces on the surfaces of the three minerals during their competitive adsorption, carbon dioxide had stronger competitive adsorption performance. The results in this study prove to a certain extent that under the low pressure and high temperature conditions, increasing the carbon dioxide concentration is more conducive to shale gas displacement, so as to improve the shale gas recovery rate.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134765"},"PeriodicalIF":6.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.fuel.2025.134745
Ruina Li , Dahai Yang , Feifan Liu , Quan Hu , Qingcheng Liu , Hua Yue , Yang Meng , Yidan Mei
The coal liquefaction technology can produce F-T diesel and methanol. In this paper, four-cylinder diesel engine bench tests were carried out under the full load condition at 1800 r/min and 2400 r/min. The combustion characteristics of F-T diesel/methanol dual fuel combustion, with the methanol proportion being 0% (F-T Diesel), 10 % (M10), 20 % (M20), and 30 % (M30), as well as the physical and structural characteristics of soot were analyzed. Chemical reaction kinetics and fluid mechanics were used to analyze the precursors and OH radicals of soot in detail, aiming to explore the influence of methanol atmosphere on the formation mechanism of soot precursors. The results show that the addition of methanol delays the maximum heat release point of combustion, prolongs the ignition delay period, and makes the maximum explosion pressure increase with the increase of the methanol blending ratio. The addition of methanol significantly reduces soot emission. With the increase of the methanol combustion ratio, the particle size decreases and the agglomeration degree increases. The addition of methanol inhibits the formation of aromatic hydrocarbons and slows down the formation rate of aromatic hydrocarbons, and the rate gradually increases with the increase of the number of aromatic hydrocarbons, enhancing the oxidation activity and reducing the formation of soot.
{"title":"Study on in-cylinder soot formation process of F-T diesel/methanol dual-fuel diesel engine","authors":"Ruina Li , Dahai Yang , Feifan Liu , Quan Hu , Qingcheng Liu , Hua Yue , Yang Meng , Yidan Mei","doi":"10.1016/j.fuel.2025.134745","DOIUrl":"10.1016/j.fuel.2025.134745","url":null,"abstract":"<div><div>The coal liquefaction technology can produce F-T diesel and methanol. In this paper, four-cylinder diesel engine bench tests were carried out under the full load condition at 1800 r/min and 2400 r/min. The combustion characteristics of F-T diesel/methanol dual fuel combustion, with the methanol proportion being 0% (F-T Diesel), 10 % (M10), 20 % (M20), and 30 % (M30), as well as the physical and structural characteristics of soot were analyzed. Chemical reaction kinetics and fluid mechanics were used to analyze the precursors and OH radicals of soot in detail, aiming to explore the influence of methanol atmosphere on the formation mechanism of soot precursors. The results show that the addition of methanol delays the maximum heat release point of combustion, prolongs the ignition delay period, and makes the maximum explosion pressure increase with the increase of the methanol blending ratio. The addition of methanol significantly reduces soot emission. With the increase of the methanol combustion ratio, the particle size decreases and the agglomeration degree increases. The addition of methanol inhibits the formation of aromatic hydrocarbons and slows down the formation rate of aromatic hydrocarbons, and the rate gradually increases with the increase of the number of aromatic hydrocarbons, enhancing the oxidation activity and reducing the formation of soot.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134745"},"PeriodicalIF":6.7,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.fuel.2025.134650
Bo Yan , Yingzhu Guo , Shujian Cheng , Liangding Dou , Yun Yang , Xiaoxiao Guo , Yangbo Chen , Weiwei Cai , Yufeng Zhang , Zhe Liu , Zhaohui Meng , Rui Mu , Dai Wang , Xue-ao Zhang
Microbial fuel cells (MFCs) convert chemical energy stored in organic matter into electrical energy through the electrochemical action of microorganisms, making them highly relevant for wastewater treatment. However, the efficiency of generating bioelectricity using nonclassical electroactive bacteria such as Escherichia coli (E. coli), which commonly exist in the waste water, remains rather low. Herein, we improve the performance of MFCs by using graphene aerogel (GA) with dispersed Ag nanowires (AgNWs) as the anode material. Introducing AgNWs into GA lowers the charge-transfer resistance of the electrode and enhance the electrochemical active surface area (ECSA), which improves charge transfer efficiency of MFCs. However, the high release of Ag+ from AgNWs and overactive charge-transfer can inhibit the bacterial activity, which compromises the operation of MFCs. Hence, the GA/AgNWs need to be optimized to minimize charge-transfer resistance while preserving bacterial activity. It is demonstrated that the power density of the MFC using GA with 1 wt% AgNWs reaches 0.98 mW/cm2, which is 60 % higher than the best-reported value of MFCs using carbon–metal composites. The results pave a new avenue for improving MFCs performance.
{"title":"Ag nanowires boost graphene aerogel as anode for charge-transfer in nonclassical electroactive microbial fuel cells","authors":"Bo Yan , Yingzhu Guo , Shujian Cheng , Liangding Dou , Yun Yang , Xiaoxiao Guo , Yangbo Chen , Weiwei Cai , Yufeng Zhang , Zhe Liu , Zhaohui Meng , Rui Mu , Dai Wang , Xue-ao Zhang","doi":"10.1016/j.fuel.2025.134650","DOIUrl":"10.1016/j.fuel.2025.134650","url":null,"abstract":"<div><div>Microbial fuel cells (MFCs) convert chemical energy stored in organic matter into electrical energy through the electrochemical action of microorganisms, making them highly relevant for wastewater treatment. However, the efficiency of generating bioelectricity using nonclassical electroactive bacteria such as <em>Escherichia coli</em> (<em>E. coli</em>), which commonly exist in the waste water, remains rather low. Herein, we improve the performance of MFCs by using graphene aerogel (GA) with dispersed Ag nanowires (AgNWs) as the anode material. Introducing AgNWs into GA lowers the charge-transfer resistance of the electrode and enhance the electrochemical active surface area (ECSA), which improves charge transfer efficiency of MFCs. However, the high release of Ag<sup>+</sup> from AgNWs and overactive charge-transfer can inhibit the bacterial activity, which compromises the operation of MFCs. Hence, the GA/AgNWs need to be optimized to minimize charge-transfer resistance while preserving bacterial activity. It is demonstrated that the power density of the MFC using GA with 1 wt% AgNWs reaches 0.98 mW/cm<sup>2</sup>, which is 60 % higher than the best-reported value of MFCs using carbon–metal composites. The results pave a new avenue for improving MFCs performance.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134650"},"PeriodicalIF":6.7,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.fuel.2025.134756
I Komang Gede Tryas Agameru Putra , Ho Xuan Duy Nguyen , Quang Khai Tran , Ocktaeck Lim
Spray characteristics are among the variables that have a direct impact on both engine performance and engine design, thus significantly affecting the ignition and emission parameters of diesel engines. This study combines experimental methods and computational fluid dynamics simulations to comprehensively investigate spray characteristics. A constant volume chamber replicating diesel engine conditions is utilized to assess the impact of incorporating absolute ethanol in diesel blends. MATLAB image processing techniques are employed to analyze the spray development images captured using a high-speed camera with the shadowgraph optical method. Macroscopic spray features, including spray penetration length, cone angle, and spray area are studied experimentally, while simulations explore microscopic features like Sauter mean diameter. The experimental matrix varies the absolute ethanol content (10%, 20%, 30%) in the blends and the injection strategies. Results reveal that ethanol addition alters the fuel’s physicochemical properties, reducing density, viscosity, and surface tension, leading to shorter penetration and broader cone angle. Blends with lower viscosity and surface tension exhibit larger cone angles, while higher-density blends boost penetration. Increasing ethanol concentration further reduces droplet size, indicating enhanced spray breakup and atomization processes. Moreover, the spray characteristics are also influenced by injection parameters highlighting the importance of an optimized injection strategy in spray development.
{"title":"Optical and computational investigations: Assessing the impact of absolute ethanol mixtures on diesel spray behavior","authors":"I Komang Gede Tryas Agameru Putra , Ho Xuan Duy Nguyen , Quang Khai Tran , Ocktaeck Lim","doi":"10.1016/j.fuel.2025.134756","DOIUrl":"10.1016/j.fuel.2025.134756","url":null,"abstract":"<div><div>Spray characteristics are among the variables that have a direct impact on both engine performance and engine design, thus significantly affecting the ignition and emission parameters of diesel engines. This study combines experimental methods and computational fluid dynamics simulations to comprehensively investigate spray characteristics. A constant volume chamber replicating diesel engine conditions is utilized to assess the impact of incorporating absolute ethanol in diesel blends. MATLAB image processing techniques are employed to analyze the spray development images captured using a high-speed camera with the shadowgraph optical method. Macroscopic spray features, including spray penetration length, cone angle, and spray area are studied experimentally, while simulations explore microscopic features like Sauter mean diameter. The experimental matrix varies the absolute ethanol content (10%, 20%, 30%) in the blends and the injection strategies. Results reveal that ethanol addition alters the fuel’s physicochemical properties, reducing density, viscosity, and surface tension, leading to shorter penetration and broader cone angle. Blends with lower viscosity and surface tension exhibit larger cone angles, while higher-density blends boost penetration. Increasing ethanol concentration further reduces droplet size, indicating enhanced spray breakup and atomization processes. Moreover, the spray characteristics are also influenced by injection parameters highlighting the importance of an optimized injection strategy in spray development.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134756"},"PeriodicalIF":6.7,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.fuel.2025.134749
Wagd Ajeeb , Diogo Melo Gomes , Rui Costa Neto , Patrícia Baptista
Hydrotreated Vegetable Oils (HVOs) have won significant attention worldwide as a viable alternative to fossil diesel in transportation. In the present study, a life cycle analysis (LCA) of the production of HVO is conducted, focused on HVO in the case of Portugal. The production process considered exploits used cooking oils (UCOs), alongside green hydrogen (GH2). SimaPro software is used to analyse the environmental impacts of the entire value chain associated with the production of GH2 and HVO. The resulting environmental impacts are also compared with other conventional scenarios that include using virgin oils and the grid mix electricity. The LCA results demonstrated that the HVO produced using GH2 and UCO has a reduction in environmental impacts by around 0.23 to 0.45 kg CO2 eq./kg HVO compared to the conventional scenarios. The lowest GWP level observed is in the UCO with PV/Wind electricity scenario at 0.304 kg CO2 eq/kg HVO, While the highest GWP is for using Palm Oil with grid mix at 0.748 kg CO2 eq/kg HVO. These findings underscore the significant influence of electricity sources and feedstock type on the GWP values in HVO production.
{"title":"Life cycle analysis of hydrotreated vegetable oils production based on green hydrogen and used cooking oils","authors":"Wagd Ajeeb , Diogo Melo Gomes , Rui Costa Neto , Patrícia Baptista","doi":"10.1016/j.fuel.2025.134749","DOIUrl":"10.1016/j.fuel.2025.134749","url":null,"abstract":"<div><div>Hydrotreated Vegetable Oils (HVOs) have won significant attention worldwide as a viable alternative to fossil diesel in transportation. In the present study, a life cycle analysis (LCA) of the production of HVO is conducted, focused on HVO in the case of Portugal. The production process considered exploits used cooking oils (UCOs), alongside green hydrogen (GH<sub>2</sub>). SimaPro software is used to analyse the environmental impacts of the entire value chain associated with the production of GH<sub>2</sub> and HVO. The resulting environmental impacts are also compared with other conventional scenarios that include using virgin oils and the grid mix electricity. The LCA results demonstrated that the HVO produced using GH<sub>2</sub> and UCO has a reduction in environmental impacts by around 0.23 to 0.45 kg CO<sub>2</sub> eq./kg HVO compared to the conventional scenarios. The lowest GWP level observed is in the UCO with PV/Wind electricity scenario at 0.304 kg CO<sub>2</sub> eq/kg HVO, While the highest GWP is for using Palm Oil with grid mix at 0.748 kg CO<sub>2</sub> eq/kg HVO. These findings underscore the significant influence of electricity sources and feedstock type on the GWP values in HVO production.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"390 ","pages":"Article 134749"},"PeriodicalIF":6.7,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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