Pub Date : 2024-11-06DOI: 10.1016/j.joei.2024.101879
Xinzhe Zhang , Weikang Han , Yuyang Zhang , Dongting Zhan , Zixiao Qi , Juan Wang , Wenlong Dong , Huaqiang Chu
In this study, the detailed mechanism of soot formation under high temperature pyrolysis of 2-methylfuran (2-MF) has been investigated by using Reactive force field molecular dynamics (ReaxFF MD) simulation. The MD analysis shows that 2-MF undergoes ring cleavage and the removal of CO/HCO/CH2CO/CH3CO, which results in the production of the C2-C4 species, promoting the formation of the initial ring molecules. The clustering of hydrocarbons by radical-chain reaction (CHRCR) mechanism plays a significant role in the mass growth of both polycyclic aromatic hydrocarbons (PAHs) and initial soot particles. The main contributors to this process are C2H2 and resonance-stabilized free radicals of C3 and C4. The H-abstraction-C2H2-addition (HACA) mechanism is important for the formation of surface active sites for PAHs and initial soot to some extent. In addition, the soot formation capacity of 2,5-dimethylfuran (25DMF) and 2-MF are compared. Under the same simulation conditions, 25DMF exhibits a higher capacity to form soot. Compared with 2-MF, 25DMF pyrolysis forms more ring-containing species at the initial stage, particularly cyclopentadiene and its derivatives. These compounds have the ability to promote the formation of PAHs, thus providing further support to the experimental-based theory.
{"title":"Formation mechanism of soot in pyrolysis of 2-methylfuran under high temperature based on ReaxFF molecular dynamics simulation","authors":"Xinzhe Zhang , Weikang Han , Yuyang Zhang , Dongting Zhan , Zixiao Qi , Juan Wang , Wenlong Dong , Huaqiang Chu","doi":"10.1016/j.joei.2024.101879","DOIUrl":"10.1016/j.joei.2024.101879","url":null,"abstract":"<div><div>In this study, the detailed mechanism of soot formation under high temperature pyrolysis of 2-methylfuran (2-MF) has been investigated by using Reactive force field molecular dynamics (ReaxFF MD) simulation. The MD analysis shows that 2-MF undergoes ring cleavage and the removal of CO/HCO/CH<sub>2</sub>CO/CH<sub>3</sub>CO, which results in the production of the C<sub>2</sub>-C<sub>4</sub> species, promoting the formation of the initial ring molecules. The clustering of hydrocarbons by radical-chain reaction (CHRCR) mechanism plays a significant role in the mass growth of both polycyclic aromatic hydrocarbons (PAHs) and initial soot particles. The main contributors to this process are C<sub>2</sub>H<sub>2</sub> and resonance-stabilized free radicals of C<sub>3</sub> and C<sub>4</sub>. The H-abstraction-C<sub>2</sub>H<sub>2</sub>-addition (HACA) mechanism is important for the formation of surface active sites for PAHs and initial soot to some extent. In addition, the soot formation capacity of 2,5-dimethylfuran (25DMF) and 2-MF are compared. Under the same simulation conditions, 25DMF exhibits a higher capacity to form soot. Compared with 2-MF, 25DMF pyrolysis forms more ring-containing species at the initial stage, particularly cyclopentadiene and its derivatives. These compounds have the ability to promote the formation of PAHs, thus providing further support to the experimental-based theory.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"118 ","pages":"Article 101879"},"PeriodicalIF":5.6,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142662899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-11-01DOI: 10.1016/j.joei.2024.101872
Huawei Zhang, Hu Chen, Yincui Li, Shengnan Deng, Zizhen Ma, Yan Tan, Ting Liu
The increasing production of waste plastics poses significant environmental and health risks. Low-density polyethylene (LDPE), a major component of plastic waste, is a high-quality feedstock for pyrolysis due to its high carbon and hydrogen content. Traditional pyrolysis methods, such as thermal cracking and one-step catalytic pyrolysis, have limitations in yield and selectivity of valuable products like light olefins. This study introduces a two-stage catalytic pyrolysis (TSCP) process aimed at enhancing the production of light olefins from LDPE. In the first stage, LDPE undergoes pyrolysis with MCM-41 catalyst, yielding a substantial number of liquid products and a minor portion of light olefins. The second stage utilizes Mg-ZSM-5 catalyst to further crack the high-temperature volatile matter into light olefins. The optimal conditions identified were 450 °C in the first stage and 500 °C in the second stage, achieving a maximum light olefin yield of 45.80 wt% and a low reaction temperature, decreasing the energy consumption. Additionally, the MCM-41 catalyst demonstrates excellent regeneration performance, with only a slight decrease in liquid yield after nine cycles. The Mg-ZSM-5 catalyst maintains high stability, with light olefin yield remaining at 83.60 % of the initial yield after 48 h of operation.
{"title":"Boosting light olefin production from pyrolysis of low-density polyethylene: A two-stage catalytic process","authors":"Huawei Zhang, Hu Chen, Yincui Li, Shengnan Deng, Zizhen Ma, Yan Tan, Ting Liu","doi":"10.1016/j.joei.2024.101872","DOIUrl":"10.1016/j.joei.2024.101872","url":null,"abstract":"<div><div>The increasing production of waste plastics poses significant environmental and health risks. Low-density polyethylene (LDPE), a major component of plastic waste, is a high-quality feedstock for pyrolysis due to its high carbon and hydrogen content. Traditional pyrolysis methods, such as thermal cracking and one-step catalytic pyrolysis, have limitations in yield and selectivity of valuable products like light olefins. This study introduces a two-stage catalytic pyrolysis (TSCP) process aimed at enhancing the production of light olefins from LDPE. In the first stage, LDPE undergoes pyrolysis with MCM-41 catalyst, yielding a substantial number of liquid products and a minor portion of light olefins. The second stage utilizes Mg-ZSM-5 catalyst to further crack the high-temperature volatile matter into light olefins. The optimal conditions identified were 450 °C in the first stage and 500 °C in the second stage, achieving a maximum light olefin yield of 45.80 wt% and a low reaction temperature, decreasing the energy consumption. Additionally, the MCM-41 catalyst demonstrates excellent regeneration performance, with only a slight decrease in liquid yield after nine cycles. The Mg-ZSM-5 catalyst maintains high stability, with light olefin yield remaining at 83.60 % of the initial yield after 48 h of operation.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101872"},"PeriodicalIF":5.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effects of carbon dioxide (CO2) addition to ethylene (C2H4)/air inverse diffusion flames (IDFs) to the air stream on soot formation characteristics are investigated with the addition ratio of 0–13.64 %. The planar laser-induced fluorescence (PLIF) and planar laser-induced incandescence (PLII) techniques, in conjunction with CoFlame and Chemkin code simulations were utilized to assess the distributions of Polycyclic Aromatic Hydrocarbons (PAHs) and Soot Volume Fraction (SVF). The findings indicate that increasing CO2 addition results in a gradual decrease in the mole fraction of hydroxyl (OH) radicals and flame temperature, accompanied by a reduction of approximately 15 % in the reaction zone height in experimental observations and 19 % in simulations. The inhibition of soot formation is evident through a consistent decline in the normalized total SVF, a decrease in the peak volume fraction of radial soot distribution, and reduced total SVFs observed across different flame sections at varying heights. In the meanwhile, increasing the CO2 doping ratio significantly reduces the peak signal intensity of PAHs, particularly affecting high molecular weight PAHs (A3-A4, A2-A3) with reductions of up to 75.5 %. Furthermore, reductions are noted in the rates of soot inception and subsequent surface growth, accompanied by an upward displacement of the initial inception and growth location. The condensation of PAHs controls the soot surface growth. The thermal and chemical effects of CO2 were differentiated by employing the virtual substance FCO2. The results suggest that the thermal effect of CO2 lowers flame temperature, reduces combustion intensity, and consequently inhibits soot nucleation. The chemical effect of CO2 competes for H radicals through the reverse reaction of CO + OH ≤> CO2+H. This process suppresses the formation and growth of PAHs, consequently leading to a reduction in soot production.
{"title":"Effects of carbon dioxide addition on soot dynamics in ethylene/air inverse diffusion flames: An experimental and computational analysis","authors":"Xu He , Jingyang Jia , Qi Xiang , Zhiwei Zhang , Dongping Chen","doi":"10.1016/j.joei.2024.101874","DOIUrl":"10.1016/j.joei.2024.101874","url":null,"abstract":"<div><div>The effects of carbon dioxide (CO<sub>2</sub>) addition to ethylene (C<sub>2</sub>H<sub>4</sub>)/air inverse diffusion flames (IDFs) to the air stream on soot formation characteristics are investigated with the addition ratio of 0–13.64 %. The planar laser-induced fluorescence (PLIF) and planar laser-induced incandescence (PLII) techniques, in conjunction with CoFlame and Chemkin code simulations were utilized to assess the distributions of Polycyclic Aromatic Hydrocarbons (PAHs) and Soot Volume Fraction (SVF). The findings indicate that increasing CO<sub>2</sub> addition results in a gradual decrease in the mole fraction of hydroxyl (OH) radicals and flame temperature, accompanied by a reduction of approximately 15 % in the reaction zone height in experimental observations and 19 % in simulations. The inhibition of soot formation is evident through a consistent decline in the normalized total SVF, a decrease in the peak volume fraction of radial soot distribution, and reduced total SVFs observed across different flame sections at varying heights. In the meanwhile, increasing the CO<sub>2</sub> doping ratio significantly reduces the peak signal intensity of PAHs, particularly affecting high molecular weight PAHs (A3-A4, A2-A3) with reductions of up to 75.5 %. Furthermore, reductions are noted in the rates of soot inception and subsequent surface growth, accompanied by an upward displacement of the initial inception and growth location. The condensation of PAHs controls the soot surface growth. The thermal and chemical effects of CO<sub>2</sub> were differentiated by employing the virtual substance FCO<sub>2</sub>. The results suggest that the thermal effect of CO<sub>2</sub> lowers flame temperature, reduces combustion intensity, and consequently inhibits soot nucleation. The chemical effect of CO<sub>2</sub> competes for H radicals through the reverse reaction of CO + OH ≤> CO<sub>2</sub>+H. This process suppresses the formation and growth of PAHs, consequently leading to a reduction in soot production.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101874"},"PeriodicalIF":5.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The study of the combustion characteristics of NH₃/bio-syngas/air under NH₃ partial cracking and elevated initial temperatures can enhance its feasibility as a practical fuel. The effects of NH₃ cracking rates (ζ) and initial temperature (T0) on the laminar burning velocity (SL), instability, and NO emissions of NH₃/bio-syngas/air premixed flames under different equivalence ratios are investigated. The results indicate that increasing ζ and T0 enhances the SL of the premixed flame, with ζ having a more pronounced effect on combustion enhancement. Virtual gas analysis reveals that pre-cracking primarily strengthens combustion through chemical effect. An increase in ζ significantly shifts the peak SL towards the fuel-rich region, while at any T0, the peak SL consistently occurs around Φ = 1.1. Increasing ζ and T0 reduces the critical radius (rc) and the critical Peclet number (Pec) of the premixed fuel, with rc decreasing more rapidly when ζ is below 30 %. The dimensionless growth rate (∑) increases with the rise in ζ and T0, consistently remaining positive, indicating an unstable state. Additionally, ∑ varies more significantly with T0 when T0 is below 450 K. When ζ is below 60 %, the NO mole fraction increases with the increase in ζ. However, at ζ = 80 %, the NO mole fraction is lower than at ζ = 40 %. Increasing T0 continually increases the NO mole fraction. Analysis of the NH3 reaction pathways indicates that NHi (i = 0, 1, 2) is closely related to the NO → N2 reduction reactions.
{"title":"The effects of NH3 pre-cracking and initial temperature on the intrinsic instability and NOx emissions of NH3/bio-syngas/air premixed flames","authors":"Lijuan Wen, Qifeng Zhu, Jingwei Zeng, Haoxin Deng, Guoyan Chen, Xiaoping Wen, Fahui Wang, Qizheng Hao","doi":"10.1016/j.joei.2024.101873","DOIUrl":"10.1016/j.joei.2024.101873","url":null,"abstract":"<div><div>The study of the combustion characteristics of NH₃/bio-syngas/air under NH₃ partial cracking and elevated initial temperatures can enhance its feasibility as a practical fuel. The effects of NH₃ cracking rates (<em>ζ</em>) and initial temperature (<em>T</em><sub><em>0</em></sub>) on the laminar burning velocity (<em>S</em><sub><em>L</em></sub>), instability, and NO emissions of NH₃/bio-syngas/air premixed flames under different equivalence ratios are investigated. The results indicate that increasing <em>ζ</em> and <em>T</em><sub><em>0</em></sub> enhances the <em>S</em><sub><em>L</em></sub> of the premixed flame, with <em>ζ</em> having a more pronounced effect on combustion enhancement. Virtual gas analysis reveals that pre-cracking primarily strengthens combustion through chemical effect. An increase in <em>ζ</em> significantly shifts the peak <em>S</em><sub><em>L</em></sub> towards the fuel-rich region, while at any <em>T</em><sub><em>0</em></sub>, the peak <em>S</em><sub><em>L</em></sub> consistently occurs around Φ = 1.1. Increasing <em>ζ</em> and <em>T</em><sub><em>0</em></sub> reduces the critical radius (<em>r</em><sub><em>c</em></sub>) and the critical Peclet number (<em>Pe</em><sub><em>c</em></sub>) of the premixed fuel, with <em>r</em><sub><em>c</em></sub> decreasing more rapidly when <em>ζ</em> is below 30 %. The dimensionless growth rate (<em>∑</em>) increases with the rise in <em>ζ</em> and <em>T</em><sub><em>0</em></sub>, consistently remaining positive, indicating an unstable state. Additionally, <em>∑</em> varies more significantly with <em>T</em><sub><em>0</em></sub> when <em>T</em><sub><em>0</em></sub> is below 450 K. When <em>ζ</em> is below 60 %, the NO mole fraction increases with the increase in <em>ζ</em>. However, at <em>ζ</em> = 80 %, the NO mole fraction is lower than at <em>ζ</em> = 40 %. Increasing <em>T</em><sub><em>0</em></sub> continually increases the NO mole fraction. Analysis of the NH<sub>3</sub> reaction pathways indicates that NH<sub>i</sub> (i = 0, 1, 2) is closely related to the NO → N<sub>2</sub> reduction reactions.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101873"},"PeriodicalIF":5.6,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-31DOI: 10.1016/j.joei.2024.101865
Rui Li , Tao Yue , Guoliang Li , Jiajia Gao , Yali Tong , Sihong Cheng , Guotao Li , Changjiang Hou , Wei Su
Selective catalytic reduction technology with NH3 as reducing agent (NH3-SCR) has been widely applied to remove NOx from stationary sources and diesel vehicles. In this paper, we conducted a bibliometric analysis to understand the research trends in NH3-SCR fields during 1994–2023. The article number was thriving, especially in China. China and USA were the predominant countries with close collaboration relationship. Chinese Academy of Sciences, Tsinghua University and Zhejiang University made greatest contributions, and Politecnico di Milano had strong academic influence. Li, Junhua was prominent author with publishing most articles and mostly cited articles. The stable core author groups had been developed, whose research focuses were identified. Applied Catalysis B: Environment and Energy was the leading journal. The analysis of most frequently cited articles and most frequently used author keywords found six main research domains, including of the low-temperature catalysts, the transition metal modified zeolites, the V-based catalysts, the deactivation and regeneration, the multi-pollutants removal, the aftertreatment system of diesel vehicles and their mechanism studies. Cu-SSZ-13, DFT, the synergistic effect and the simultaneous removal of NOx and other air pollutants got recent attentions. These findings enriched the understandings in NH3-SCR fields, giving some guidelines for the future research.
{"title":"Global trends on NH3-SCR research for NOx control during 1994–2023: A bibliometric analysis","authors":"Rui Li , Tao Yue , Guoliang Li , Jiajia Gao , Yali Tong , Sihong Cheng , Guotao Li , Changjiang Hou , Wei Su","doi":"10.1016/j.joei.2024.101865","DOIUrl":"10.1016/j.joei.2024.101865","url":null,"abstract":"<div><div>Selective catalytic reduction technology with NH<sub>3</sub> as reducing agent (NH<sub>3</sub>-SCR) has been widely applied to remove NO<sub>x</sub> from stationary sources and diesel vehicles. In this paper, we conducted a bibliometric analysis to understand the research trends in NH<sub>3</sub>-SCR fields during 1994–2023. The article number was thriving, especially in China. China and USA were the predominant countries with close collaboration relationship. Chinese Academy of Sciences, Tsinghua University and Zhejiang University made greatest contributions, and Politecnico di Milano had strong academic influence. Li, Junhua was prominent author with publishing most articles and mostly cited articles. The stable core author groups had been developed, whose research focuses were identified. <em>Applied Catalysis B: Environment and Energy</em> was the leading journal. The analysis of most frequently cited articles and most frequently used author keywords found six main research domains, including of the low-temperature catalysts, the transition metal modified zeolites, the V-based catalysts, the deactivation and regeneration, the multi-pollutants removal, the aftertreatment system of diesel vehicles and their mechanism studies. Cu-SSZ-13, DFT, the synergistic effect and the simultaneous removal of NO<sub>x</sub> and other air pollutants got recent attentions. These findings enriched the understandings in NH<sub>3</sub>-SCR fields, giving some guidelines for the future research.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101865"},"PeriodicalIF":5.6,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-30DOI: 10.1016/j.joei.2024.101868
Yan Wu , Jie Hu , Yi Lin , Peng Chen , Gang Chen , Zhihong Wang
Achieving carbon neutrality necessitates the adoption of zero-carbon fuels in engine applications, with ammonia emerging as an up-and-coming candidate due to its favorable safety profile and advantages in storage and transportation. This study experimentally investigated the feasibility of an ammonia-gasoline dual-fuel (AGDF) engine to achieve comparable power output and satisfactory carbon reduction without changing the main structural parameters of the engine. A four-cylinder, naturally aspirated, spark ignition engine was used to investigate the impact of ammonia energy ratio (AER), engine base torque and engine speed on the engine performance, combustion evolution and emission characteristics. The findings reveal that the brake thermal efficiency (BTE) in AGDF mode is lower than in gasoline-only mode, primarily due to the reduced combustion activity. However, this efficiency decline becomes noticeable only when the AER exceeds 15 %. Additionally, at high AERs and high engine base torques, the delayed effect of ammonia fuel on the main combustion period results in a double-peak pattern, which limits the energy output but presents opportunities for phase optimization. The study also examined three incomplete combustion emissions, each exhibiting distinct behaviors. Except for ammonia slip, adding ammonia fuel does not significantly affect carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions, particularly at AERs below 25 %. Nevertheless, nitrogen oxide (NOx) emissions under AGDF combustion are significantly higher than under gasoline alone in most instances. Crucially, the study demonstrates the carbon reduction potential of ammonia fuel across different engine loads, with a maximum carbon dioxide (CO2) reduction of 46.8 % at a 35 % AER. It is anticipated that further optimization of the combustion phase will improve the capability for carbon reduction.
{"title":"Experimental study of ammonia energy ratio on combustion and emissions from ammonia-gasoline dual-fuel engine at various load conditions","authors":"Yan Wu , Jie Hu , Yi Lin , Peng Chen , Gang Chen , Zhihong Wang","doi":"10.1016/j.joei.2024.101868","DOIUrl":"10.1016/j.joei.2024.101868","url":null,"abstract":"<div><div>Achieving carbon neutrality necessitates the adoption of zero-carbon fuels in engine applications, with ammonia emerging as an up-and-coming candidate due to its favorable safety profile and advantages in storage and transportation. This study experimentally investigated the feasibility of an ammonia-gasoline dual-fuel (AGDF) engine to achieve comparable power output and satisfactory carbon reduction without changing the main structural parameters of the engine. A four-cylinder, naturally aspirated, spark ignition engine was used to investigate the impact of ammonia energy ratio (AER), engine base torque and engine speed on the engine performance, combustion evolution and emission characteristics. The findings reveal that the brake thermal efficiency (BTE) in AGDF mode is lower than in gasoline-only mode, primarily due to the reduced combustion activity. However, this efficiency decline becomes noticeable only when the AER exceeds 15 %. Additionally, at high AERs and high engine base torques, the delayed effect of ammonia fuel on the main combustion period results in a double-peak pattern, which limits the energy output but presents opportunities for phase optimization. The study also examined three incomplete combustion emissions, each exhibiting distinct behaviors. Except for ammonia slip, adding ammonia fuel does not significantly affect carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions, particularly at AERs below 25 %. Nevertheless, nitrogen oxide (NOx) emissions under AGDF combustion are significantly higher than under gasoline alone in most instances. Crucially, the study demonstrates the carbon reduction potential of ammonia fuel across different engine loads, with a maximum carbon dioxide (CO<sub>2</sub>) reduction of 46.8 % at a 35 % AER. It is anticipated that further optimization of the combustion phase will improve the capability for carbon reduction.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101868"},"PeriodicalIF":5.6,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-29DOI: 10.1016/j.joei.2024.101870
Qingsong Zou , Kejiang Li , Xiangyu He , Alberto N. Conejo , Jianliang Zhang , Chunhe Jiang , Zeng Liang , Zonghao Yang
The carbon neutrality strategy presents both challenges and opportunities for the metallurgical industry. Hydrogen, recognized as a green energy source, demonstrates significant potential for application in metallurgy. The negative impact of carbon deposition on catalysts is a significant challenge in the large-scale industrial application of methane dry reforming to produce hydrogen-rich reducing gases for ironmaking. This paper investigates the reaction mechanism through thermodynamic calculations and molecular dynamics simulations, systematically examining the effects of temperature, pressure, and feed ratio on the composition of gas products and the amount of carbon precipitation during the preparation process of hydrogen-rich reduction gas. The optimal conditions to produce high-quality reducing gas are identified to be a CO₂/CH₄ ratio of 0.8 at 1100K and 1 atm. At elevated temperatures, increasing the amount of carbon dioxide can reduce the amount of precipitated carbon, while the opposite is true at lower temperatures. The carbon absorbed by the nickel-based catalyst primarily originates from methane, while hydrogen ions activate carbon dioxide to produce carbon monoxide or carboxyl groups. By elucidating the reaction mechanism and quantifying the carbon precipitation, we provide theoretical guidance for industrial application.
{"title":"Thermodynamic and molecular dynamics study of methane dry reforming","authors":"Qingsong Zou , Kejiang Li , Xiangyu He , Alberto N. Conejo , Jianliang Zhang , Chunhe Jiang , Zeng Liang , Zonghao Yang","doi":"10.1016/j.joei.2024.101870","DOIUrl":"10.1016/j.joei.2024.101870","url":null,"abstract":"<div><div>The carbon neutrality strategy presents both challenges and opportunities for the metallurgical industry. Hydrogen, recognized as a green energy source, demonstrates significant potential for application in metallurgy. The negative impact of carbon deposition on catalysts is a significant challenge in the large-scale industrial application of methane dry reforming to produce hydrogen-rich reducing gases for ironmaking. This paper investigates the reaction mechanism through thermodynamic calculations and molecular dynamics simulations, systematically examining the effects of temperature, pressure, and feed ratio on the composition of gas products and the amount of carbon precipitation during the preparation process of hydrogen-rich reduction gas. The optimal conditions to produce high-quality reducing gas are identified to be a CO₂/CH₄ ratio of 0.8 at 1100K and 1 atm. At elevated temperatures, increasing the amount of carbon dioxide can reduce the amount of precipitated carbon, while the opposite is true at lower temperatures. The carbon absorbed by the nickel-based catalyst primarily originates from methane, while hydrogen ions activate carbon dioxide to produce carbon monoxide or carboxyl groups. By elucidating the reaction mechanism and quantifying the carbon precipitation, we provide theoretical guidance for industrial application.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101870"},"PeriodicalIF":5.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-29DOI: 10.1016/j.joei.2024.101871
Muhammad Nauman , Jianfeng Pan , Qingbo Lu , Yi Zhang , Evans K. Quaye , Feiyang Li , Wenming Yang
This paper presents a numerical investigation of premixed methane/oxygen heterogeneous reaction characteristics in a micro-catalytic combustion chamber under various boundary and wall thermophysical conditions. A 3-D model was simulated using ANSYS Fluent and validated against experimental data, with a maximum difference of only 1.92 % using a pure heterogeneous reaction. This study aims to analyze the wall boundary conditions and thermophysical factors that influence chemically and thermally during heterogeneous reactions. The results show that, with an increase in inlet velocity from 1 m/s to 10 m/s, the maximum heat produced by the reaction increases 52.67 % and the temperature of the channel as well as the outer wall increases accordingly. Using a 2.5 m/s inlet velocity, we found that the maximum external wall temperature uniformity coefficient was 0.1911. Furthermore, it was observed that as the heterogeneous reaction progresses, Platinum's surface coverage and the H(s) site coverage increase; however, the O(s), OH(s), CO(s), and C(s) site coverage decreases. Additionally, low convective heat transfer and wall thermal conductivity increase the efficiency of heterogeneous reactions and methane conversion. As a result of the low wall thermal conductivity, the outer wall temperature uniformity coefficient was 0.2863, while the methane conversion rate was 79.05 %. According to the results, higher thermal resistance increased the methane conversion rate from 68.18 % to 79.05 %, and the combustion process within the micro-catalytic combustor was uniform and controlled, thus enhancing its efficiency. The results of this study provide useful insights for optimizing micro-combustors, paving the way for future improvements in their design and operational efficiency.
{"title":"Effects of thermophysical properties on heterogeneous reaction dynamics of methane/oxygen mixtures in a micro catalytic combustion chamber","authors":"Muhammad Nauman , Jianfeng Pan , Qingbo Lu , Yi Zhang , Evans K. Quaye , Feiyang Li , Wenming Yang","doi":"10.1016/j.joei.2024.101871","DOIUrl":"10.1016/j.joei.2024.101871","url":null,"abstract":"<div><div>This paper presents a numerical investigation of premixed methane/oxygen heterogeneous reaction characteristics in a micro-catalytic combustion chamber under various boundary and wall thermophysical conditions. A 3-D model was simulated using ANSYS Fluent and validated against experimental data, with a maximum difference of only 1.92 % using a pure heterogeneous reaction. This study aims to analyze the wall boundary conditions and thermophysical factors that influence chemically and thermally during heterogeneous reactions. The results show that, with an increase in inlet velocity from 1 m/s to 10 m/s, the maximum heat produced by the reaction increases 52.67 % and the temperature of the channel as well as the outer wall increases accordingly. Using a 2.5 m/s inlet velocity, we found that the maximum external wall temperature uniformity coefficient was 0.1911. Furthermore, it was observed that as the heterogeneous reaction progresses, Platinum's surface coverage and the H<sub>(s)</sub> site coverage increase; however, the O<sub>(s)</sub>, OH<sub>(s)</sub>, CO<sub>(s)</sub>, and C<sub>(s)</sub> site coverage decreases. Additionally, low convective heat transfer and wall thermal conductivity increase the efficiency of heterogeneous reactions and methane conversion. As a result of the low wall thermal conductivity, the outer wall temperature uniformity coefficient was 0.2863, while the methane conversion rate was 79.05 %. According to the results, higher thermal resistance increased the methane conversion rate from 68.18 % to 79.05 %, and the combustion process within the micro-catalytic combustor was uniform and controlled, thus enhancing its efficiency. The results of this study provide useful insights for optimizing micro-combustors, paving the way for future improvements in their design and operational efficiency.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101871"},"PeriodicalIF":5.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-28DOI: 10.1016/j.joei.2024.101867
Yuan Zhuang , Yihan Li , Rui Zhai , Yuhan Huang , Xinyan Wang , Lei Tang , Ke Wang , Shancai Tang , Zhihong Lin
Ammonia/methanol co-combustion is considered an effective liquid-liquid blending strategy to enhance the combustion performance of ammonia. However, both methanol and ammonia have high latent heats of vaporization, which necessitate significant heat absorption during the vaporization process. This often results in excessively low ambient temperatures before the ignition of the mixture, negatively affecting low-temperature ignition and combustion. To improve the combustion characteristics of ammonia/methanol blends, this study proposes the addition of nitromethane, forming a ternary blend of ammonia/methanol/nitromethane to enhance fuel performance. To evaluate the impact of nitromethane on the combustion mechanism of ammonia/methanol blends, this study utilizes synchronous vacuum ultraviolet photoionization mass spectrometry to analyze the oxidation reactions of the ammonia/methanol/nitromethane blends. Based on the Brequigny model, cross-reactions involving C-N bonds and reactions related to nitromethane were incorporated for model modification, resulting in the newly modified model, termed A-M. Pathway and sensitivity analyses, as well as ignition delay time simulations, were conducted to further understand the combustion process. The results indicate that the addition of nitromethane to the ammonia/methanol blend lowers the initial reaction temperature from 860 K to 740 K and increases nitrogen oxide (NOx) concentrations at 1050 K. At 800 K, nitromethane reduces the conversion of NH2 to NH3, thereby enhancing ammonia consumption and altering the NOx consumption pathway. Furthermore, at 1020 K, 98.6 % of H2NO reacts with H to form NH2, which is a crucial species in ammonia regeneration. Additionally, at 1020 K, 90.8 % of nitromethane decomposes through the reaction CH3NO2(+M) = CH3 + NO2(+M), contributing to increased NOx emissions. Moreover, the incorporation of nitromethane significantly reduces the ignition delay time of ammonia/methanol blends, demonstrating its potential to improve the overall combustion performance of these mixtures.
氨/甲醇共燃被认为是一种有效的液-液混合策略，可提高氨的燃烧性能。然而，甲醇和氨的汽化潜热都很高，因此在汽化过程中必须大量吸热。这通常会导致混合物点火前的环境温度过低，从而对低温点火和燃烧产生不利影响。为改善氨/甲醇混合物的燃烧特性，本研究提出添加硝基甲烷，形成氨/甲醇/硝基甲烷三元混合物，以提高燃料性能。为了评估硝基甲烷对氨/甲醇混合物燃烧机理的影响，本研究利用同步真空紫外光离子化质谱仪分析了氨/甲醇/硝基甲烷混合物的氧化反应。在布雷基尼模型的基础上，加入了涉及 C-N 键的交叉反应和与硝基甲烷有关的反应，对模型进行了修改，从而得到了新修改的模型，称为 A-M。为进一步了解燃烧过程，进行了路径和敏感性分析以及点火延迟时间模拟。结果表明，在氨/甲醇混合物中加入硝基甲烷可将初始反应温度从 860 K 降低到 740 K，并增加 1050 K 时的氮氧化物（NOx）浓度。此外，在 1020 K 时，98.6% 的 H2NO 与 H 反应生成 NH2，而 NH2 是氨再生过程中的关键物种。此外，在 1020 K 时，90.8% 的硝基甲烷通过反应 CH3NO2(+M) = CH3 + NO2(+M) 分解，导致氮氧化物排放量增加。此外，硝基甲烷的加入大大缩短了氨/甲醇混合物的点火延迟时间，证明了其改善这些混合物整体燃烧性能的潜力。
{"title":"Research on the impact of nitromethane on the combustion mechanism of ammonia/methanol blends","authors":"Yuan Zhuang , Yihan Li , Rui Zhai , Yuhan Huang , Xinyan Wang , Lei Tang , Ke Wang , Shancai Tang , Zhihong Lin","doi":"10.1016/j.joei.2024.101867","DOIUrl":"10.1016/j.joei.2024.101867","url":null,"abstract":"<div><div>Ammonia/methanol co-combustion is considered an effective liquid-liquid blending strategy to enhance the combustion performance of ammonia. However, both methanol and ammonia have high latent heats of vaporization, which necessitate significant heat absorption during the vaporization process. This often results in excessively low ambient temperatures before the ignition of the mixture, negatively affecting low-temperature ignition and combustion. To improve the combustion characteristics of ammonia/methanol blends, this study proposes the addition of nitromethane, forming a ternary blend of ammonia/methanol/nitromethane to enhance fuel performance. To evaluate the impact of nitromethane on the combustion mechanism of ammonia/methanol blends, this study utilizes synchronous vacuum ultraviolet photoionization mass spectrometry to analyze the oxidation reactions of the ammonia/methanol/nitromethane blends. Based on the Brequigny model, cross-reactions involving C-N bonds and reactions related to nitromethane were incorporated for model modification, resulting in the newly modified model, termed A-M. Pathway and sensitivity analyses, as well as ignition delay time simulations, were conducted to further understand the combustion process. The results indicate that the addition of nitromethane to the ammonia/methanol blend lowers the initial reaction temperature from 860 K to 740 K and increases nitrogen oxide (NO<sub>x</sub>) concentrations at 1050 K. At 800 K, nitromethane reduces the conversion of NH<sub>2</sub> to NH<sub>3</sub>, thereby enhancing ammonia consumption and altering the NO<sub>x</sub> consumption pathway. Furthermore, at 1020 K, 98.6 % of H<sub>2</sub>NO reacts with H to form NH<sub>2</sub>, which is a crucial species in ammonia regeneration. Additionally, at 1020 K, 90.8 % of nitromethane decomposes through the reaction CH<sub>3</sub>NO<sub>2</sub>(+M) = CH<sub>3</sub> + NO<sub>2</sub>(+M), contributing to increased NO<sub>x</sub> emissions. Moreover, the incorporation of nitromethane significantly reduces the ignition delay time of ammonia/methanol blends, demonstrating its potential to improve the overall combustion performance of these mixtures.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101867"},"PeriodicalIF":5.6,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-24DOI: 10.1016/j.joei.2024.101859
Xiangjie Liu , Xin Zhang , Khantaphong Charoenkal , Qiaoxia Yuan , Hongliang Cao
The yield and higher heating value (HHV) of bio-oil products are significant performance parameters for the hydrothermal conversion of high-water and high-lipid biomass. Machine learning (ML) modeling prediction is a fast and convenient means of obtaining performance parameters. An informative dataset with 243 samples was prepared, and two highly adapted ML algorithms were used: Random Forest (RF) and Extreme Gradient Boosting Tree (XGBoost). It is interesting to note that the developed ML models demonstrated great prediction ability; for example, the regression coefficient () of the XGBoost model for yield and HHV prediction was as high as 0.942 and 0.940, respectively. Furthermore, partial dependence plots (PDP) and SHapley Additive exPlanations (SHAP) interpretability methodologies were adopted to address the main contributions of the feature identification and response behavior analysis of the features. The results demonstrated that the biomass composition had the greatest effect on bio-oil yield, with fat contributing up to 40 %. In contrast, the elemental composition had the most significant effect on the HHV of bio-oil. Notably, hydrogen content affected the HHV of up to 4.5 units. The interaction response behavior showed that the interaction of the process parameters with feedstock properties was most common and significant. The information obtained from the response mechanism can be used to enhance the subsequent hydrothermal fuel preparation process for bio-oils.
{"title":"Hydrothermal bio-oil yield and higher heating value of high moisture and lipid biomass: Machine learning modeling and feature response behavior analysis","authors":"Xiangjie Liu , Xin Zhang , Khantaphong Charoenkal , Qiaoxia Yuan , Hongliang Cao","doi":"10.1016/j.joei.2024.101859","DOIUrl":"10.1016/j.joei.2024.101859","url":null,"abstract":"<div><div>The yield and higher heating value (HHV) of bio-oil products are significant performance parameters for the hydrothermal conversion of high-water and high-lipid biomass. Machine learning (ML) modeling prediction is a fast and convenient means of obtaining performance parameters. An informative dataset with 243 samples was prepared, and two highly adapted ML algorithms were used: Random Forest (RF) and Extreme Gradient Boosting Tree (XGBoost). It is interesting to note that the developed ML models demonstrated great prediction ability; for example, the regression coefficient (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup></mrow></math></span>) of the XGBoost model for yield and HHV prediction was as high as 0.942 and 0.940, respectively. Furthermore, partial dependence plots (PDP) and SHapley Additive exPlanations (SHAP) interpretability methodologies were adopted to address the main contributions of the feature identification and response behavior analysis of the features. The results demonstrated that the biomass composition had the greatest effect on bio-oil yield, with fat contributing up to 40 %. In contrast, the elemental composition had the most significant effect on the HHV of bio-oil. Notably, hydrogen content affected the HHV of up to 4.5 units. The interaction response behavior showed that the interaction of the process parameters with feedstock properties was most common and significant. The information obtained from the response mechanism can be used to enhance the subsequent hydrothermal fuel preparation process for bio-oils.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"117 ","pages":"Article 101859"},"PeriodicalIF":5.6,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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