Pub Date : 2025-11-29DOI: 10.1016/j.pecs.2025.101264
Morteza Hosseinpour , Mohammad Fakhroleslam , Mohsen Salimi , Michael Short , Anh N. Phan , Michael T. Timko , Tohid N. Borhani
Wet biomass conversion in hot compressed water (HCW) processes operating at temperatures above 250 °C and pressures above 4 MPa offer a promising pathway towards sustainable production of biofuels. This paper provides a multiscale view of HCW, spanning from molecular-level mechanisms to commercialisation and scale-up challenges of related technologies, emphasising the need for scientific and technological innovations, policy support, and market incentives. Key aspects such as sustainability, environmental impact and economic feasibility are critically discussed. Key deployment challenges include catalyst selection, deactivation, reactor design, and process optimisation. Integration with renewable energy systems, such as solar and geothermal, and carbon capture and utilisation technologies is proposed to tackle the high energy requirements and environmental impact of HCW processes. Current developments in data-driven modelling and mechanistic simulations as useful tools that facilitate process analysis and optimisation are also reviewed. Compact, integrated and intensified HCW processes with energy recovery are central to advancing the bioeconomy. This study aims to advance the current state of HCW technologies and outlines a roadmap for future research and technological development integrated with renewable energy systems in more sustainable ways. In summary, this paper is expected to serve as a reference for researchers and industry professionals, providing a guide for addressing real-world deployment issues in HCW integrated technologies and fostering further progress in a field that often focuses more on fundamental chemistry.
{"title":"Sustainable conversion of wet biomass, algae, and food waste to fuels in hot compressed water: Multi-Scale analysis","authors":"Morteza Hosseinpour , Mohammad Fakhroleslam , Mohsen Salimi , Michael Short , Anh N. Phan , Michael T. Timko , Tohid N. Borhani","doi":"10.1016/j.pecs.2025.101264","DOIUrl":"10.1016/j.pecs.2025.101264","url":null,"abstract":"<div><div>Wet biomass conversion in hot compressed water (HCW) processes operating at temperatures above 250 °C and pressures above 4 MPa offer a promising pathway towards sustainable production of biofuels. This paper provides a multiscale view of HCW, spanning from molecular-level mechanisms to commercialisation and scale-up challenges of related technologies, emphasising the need for scientific and technological innovations, policy support, and market incentives. Key aspects such as sustainability, environmental impact and economic feasibility are critically discussed. Key deployment challenges include catalyst selection, deactivation, reactor design, and process optimisation. Integration with renewable energy systems, such as solar and geothermal, and carbon capture and utilisation technologies is proposed to tackle the high energy requirements and environmental impact of HCW processes. Current developments in data-driven modelling and mechanistic simulations as useful tools that facilitate process analysis and optimisation are also reviewed. Compact, integrated and intensified HCW processes with energy recovery are central to advancing the bioeconomy. This study aims to advance the current state of HCW technologies and outlines a roadmap for future research and technological development integrated with renewable energy systems in more sustainable ways. In summary, this paper is expected to serve as a reference for researchers and industry professionals, providing a guide for addressing real-world deployment issues in HCW integrated technologies and fostering further progress in a field that often focuses more on fundamental chemistry.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"112 ","pages":"Article 101264"},"PeriodicalIF":37.0,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681504","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 : 2025-11-08DOI: 10.1016/j.pecs.2025.101262
Tianbao Gu , Matej Huš , Samuel Simon Araya , Blaž Likozar , Fausto Gallucci , Vincenzo Liso
Transforming ammonia (NH3) synthesis from the energy-intensive, fossil-fuel-dependent conventional Haber-Bosch (HB) process to a flexible, green hydrogen-based process is pivotal for decarbonization and enabling NH3 utilization in the energy sector. The conventional HB process, operating under high temperature and pressure, is incompatible with green hydrogen systems and economically unviable for downscaled NH3 production integrated with intermittent renewable energies . Therefore, developing alternatives capable of synthesizing NH3 under moderate conditions is crucial for achieving green NH3 production. This necessity has driven the development of a range of emerging technologies, including thermocatalytic, electrocatalytic, photocatalytic, and plasma-assisted processes, amongst which thermocatalysis stands out in terms of production rate, technology readiness, and economic feasibility, demonstrating the greatest potential for NH3 synthesis transformation. This review provides a comprehensive overview of advanced thermocatalytic NH3 synthesis beyond conventional HB process and the system integration with renewable sources. It highlights key limitations and advances in implementing new materials and auxiliary techniques, outlining the challenges and mitigation strategies for achieving high NH3 productivity under mild conditions. Alongside multiscale modeling studies, the review covers catalyst development, reactor intensification, process integration, and system evaluation, examining progress and conducting meta-analysis in reaction mechanisms, emerging separation technologies, and system integration. Scientific obstacles, economic analysis, and environmental impacts are thoroughly discussed, offering state-of-the-art insights into mild NH3 synthesis from fundamental research to practical applications. Additionally, recent industrial projects of green NH3 production are summarized, showcasing scalability and commercial viability. Finally, the remaining challenges and opportunities in advanced thermocatalytic NH3 synthesis are outlined, identifying future research frontiers.
{"title":"Thermocatalytic ammonia synthesis beyond conventional Haber-Bosch: Principles, advances, challenges and opportunities","authors":"Tianbao Gu , Matej Huš , Samuel Simon Araya , Blaž Likozar , Fausto Gallucci , Vincenzo Liso","doi":"10.1016/j.pecs.2025.101262","DOIUrl":"10.1016/j.pecs.2025.101262","url":null,"abstract":"<div><div>Transforming ammonia (NH<sub>3</sub>) synthesis from the energy-intensive, fossil-fuel-dependent conventional Haber-Bosch (HB) process to a flexible, green hydrogen-based process is pivotal for decarbonization and enabling NH<sub>3</sub> utilization in the energy sector. The conventional HB process, operating under high temperature and pressure, is incompatible with green hydrogen systems and economically unviable for downscaled NH<sub>3</sub> production integrated with intermittent renewable energies . Therefore, developing alternatives capable of synthesizing NH<sub>3</sub> under moderate conditions is crucial for achieving green NH<sub>3</sub> production. This necessity has driven the development of a range of emerging technologies, including thermocatalytic, electrocatalytic, photocatalytic, and plasma-assisted processes, amongst which thermocatalysis stands out in terms of production rate, technology readiness, and economic feasibility, demonstrating the greatest potential for NH<sub>3</sub> synthesis transformation. This review provides a comprehensive overview of advanced thermocatalytic NH<sub>3</sub> synthesis beyond conventional HB process and the system integration with renewable sources. It highlights key limitations and advances in implementing new materials and auxiliary techniques, outlining the challenges and mitigation strategies for achieving high NH<sub>3</sub> productivity under mild conditions. Alongside multiscale modeling studies, the review covers catalyst development, reactor intensification, process integration, and system evaluation, examining progress and conducting meta-analysis in reaction mechanisms, emerging separation technologies, and system integration. Scientific obstacles, economic analysis, and environmental impacts are thoroughly discussed, offering state-of-the-art insights into mild NH<sub>3</sub> synthesis from fundamental research to practical applications. Additionally, recent industrial projects of green NH<sub>3</sub> production are summarized, showcasing scalability and commercial viability. Finally, the remaining challenges and opportunities in advanced thermocatalytic NH<sub>3</sub> synthesis are outlined, identifying future research frontiers.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"112 ","pages":"Article 101262"},"PeriodicalIF":37.0,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463275","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 : 2025-10-17DOI: 10.1016/j.pecs.2025.101253
Xinke Miao , Denghao Zhu , Jun Deng , Robert Dibble , Guangyu Dong , Liguang Li
For developing next-generation high performance internal combustion engines, the cycle-resolved, real-time in-cylinder combustion information acquisition can be a crucial factor. Ion current detection technology has emerged as a cost-effective diagnostic approach for this purpose. Over the past decades, extensive experimental and numerical studies have been carried out to investigate ion current characteristics. This review highlights recent progress in both the fundamental understanding and practical applications of ion current detection technology. Firstly, the principles of flame ionization, the reaction model development and ion current detection system design are introduced. Then the relationships between ion current signals and combustion behaviors are examined across different setups, ranging from testing combustors to practical engines. Accordingly, the applications of ion current in engine combustion diagnostics and control are then discussed, with emphasis on combustion status identification and optimization. Finally, the key challenges, the potential and the developing tendency of ion current detection technology are also analyzed in this review. The results clearly demonstrate that: Among various in-cylinder combustion diagnostic methods for internal combustion engines, ion current detection technology holds unique advantages in terms of combustion information richness, low cost, and ease of maintenance. Over the past decades, particularly in the last ten years, the shortcomings observed in previous studies—such as the strong influence of near-ion probe flame conditions on the signals, and the weak linear correlation between the signals and specific combustion parameters—have been significantly mitigated through fundamental innovations in detection system design and electronics circuit optimization. In such a context, the high accessibility of ion current signal data, combined with the large-scale data processing capabilities of artificial intelligence models, is expected to make this technology one of the most promising approaches to achieve next-generation intelligence engine combustion control. Overall, by integrating the ion current signal with other information from engine sensing systems, this detection technology is poised to drive profound transformations regarding the engine system design, performance calibration, and cycle-resolved (even intra-cycle) engine combustion control.
{"title":"Advances in ion current detection technology for engine applications","authors":"Xinke Miao , Denghao Zhu , Jun Deng , Robert Dibble , Guangyu Dong , Liguang Li","doi":"10.1016/j.pecs.2025.101253","DOIUrl":"10.1016/j.pecs.2025.101253","url":null,"abstract":"<div><div>For developing next-generation high performance internal combustion engines, the cycle-resolved, real-time in-cylinder combustion information acquisition can be a crucial factor. Ion current detection technology has emerged as a cost-effective diagnostic approach for this purpose. Over the past decades, extensive experimental and numerical studies have been carried out to investigate ion current characteristics. This review highlights recent progress in both the fundamental understanding and practical applications of ion current detection technology. Firstly, the principles of flame ionization, the reaction model development and ion current detection system design are introduced. Then the relationships between ion current signals and combustion behaviors are examined across different setups, ranging from testing combustors to practical engines. Accordingly, the applications of ion current in engine combustion diagnostics and control are then discussed, with emphasis on combustion status identification and optimization. Finally, the key challenges, the potential and the developing tendency of ion current detection technology are also analyzed in this review. The results clearly demonstrate that: Among various in-cylinder combustion diagnostic methods for internal combustion engines, ion current detection technology holds unique advantages in terms of combustion information richness, low cost, and ease of maintenance. Over the past decades, particularly in the last ten years, the shortcomings observed in previous studies—such as the strong influence of near-ion probe flame conditions on the signals, and the weak linear correlation between the signals and specific combustion parameters—have been significantly mitigated through fundamental innovations in detection system design and electronics circuit optimization. In such a context, the high accessibility of ion current signal data, combined with the large-scale data processing capabilities of artificial intelligence models, is expected to make this technology one of the most promising approaches to achieve next-generation intelligence engine combustion control. Overall, by integrating the ion current signal with other information from engine sensing systems, this detection technology is poised to drive profound transformations regarding the engine system design, performance calibration, and cycle-resolved (even intra-cycle) engine combustion control.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"112 ","pages":"Article 101253"},"PeriodicalIF":37.0,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323602","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 : 2025-09-25DOI: 10.1016/j.pecs.2025.101252
Chengming He , Peng Zhang , Chung K. Law
Binary droplet collisions, relevant for various natural phenomena and technological processes, embodies a rich fluid-dynamical platform covering a wide range of physical scales. This review begins with the collision between two identical droplets to reveal the underlying physics of the transition between droplet coalescence, bouncing, and separation. The interplay between the macroscopic droplet motion, the internal flow, and the microscopic interfacial gas film dynamics involving rarefied flow and van der Waals molecular force reflect the essential multi-scale and multi-physics characteristics of the collision dynamics. The review then discusses the collision between unequal-sized droplets, non-Newtonian fluids, dissimilar fluids, and the analogical jet-jet collisions. Fundamental understanding on the basic binary droplet collisions phenomena and its inference on practical processes is emphasized.
{"title":"Dynamics of binary droplet collisions","authors":"Chengming He , Peng Zhang , Chung K. Law","doi":"10.1016/j.pecs.2025.101252","DOIUrl":"10.1016/j.pecs.2025.101252","url":null,"abstract":"<div><div>Binary droplet collisions, relevant for various natural phenomena and technological processes, embodies a rich fluid-dynamical platform covering a wide range of physical scales. This review begins with the collision between two identical droplets to reveal the underlying physics of the transition between droplet coalescence, bouncing, and separation. The interplay between the macroscopic droplet motion, the internal flow, and the microscopic interfacial gas film dynamics involving rarefied flow and van der Waals molecular force reflect the essential multi-scale and multi-physics characteristics of the collision dynamics. The review then discusses the collision between unequal-sized droplets, non-Newtonian fluids, dissimilar fluids, and the analogical jet-jet collisions. Fundamental understanding on the basic binary droplet collisions phenomena and its inference on practical processes is emphasized.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"111 ","pages":"Article 101252"},"PeriodicalIF":37.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157009","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 : 2025-09-25DOI: 10.1016/j.pecs.2025.101251
Yuxuan Ma , Shangqing Tao , Zhengda Guo , Yan Gu , Zhiqiang Zhao , Zhonghua Li , Shiyu Ding , Suk Ho Chung , Osamu Fujita , Longhua Hu
Space exploration is a shared human aspiration that presents significant challenges, with fire being a major threat. The unique low-gravity, reduced-buoyancy environments of spacecraft and extraterrestrial habitats profoundly alter fluid dynamics, chemical reactions, and heat-mass transfer, leading to drastic changes in fire behavior. Understanding the solid material combustion under these conditions is vital for spacecraft fire safety and advances fundamental combustion science. This review synthesizes research on flame spread over solid materials under reduced buoyancy/gravity over the past half-century. It uniquely integrates the studies conducted in micro- and partial-gravities with ground-based experiments designed to mimic these environments. The review begins with the theoretical models defining the flame behavior and examines experimental findings from low gravities. These results reveal the important roles of “smothering” effects and radiative heat loss due to the suppressed natural convection, which drive a transition from two-dimensional to three-dimensional flame structures. Ground-based simulation methodologies, including reduced pressure environments and narrow channel apparatus, are critically examined for their ability to replicate low gravities. Stagnation point low-stretch diffusion flames are also included as a ground-based method to simulate the reduced-buoyancy effects on the spreading flame front from a more microscopic perspective. By comparing actual low-gravity data with simulated environments, the review introduces key similarity laws but also discusses the limitations of these methods in fully capturing low-gravity combustion dynamics. As the first integrated review of this topic, this work provides essential insights for ensuring the fire safety of human space exploration in the decades to come.
{"title":"Flame spread over solid materials under reduced buoyancy/gravity","authors":"Yuxuan Ma , Shangqing Tao , Zhengda Guo , Yan Gu , Zhiqiang Zhao , Zhonghua Li , Shiyu Ding , Suk Ho Chung , Osamu Fujita , Longhua Hu","doi":"10.1016/j.pecs.2025.101251","DOIUrl":"10.1016/j.pecs.2025.101251","url":null,"abstract":"<div><div>Space exploration is a shared human aspiration that presents significant challenges, with fire being a major threat. The unique low-gravity, reduced-buoyancy environments of spacecraft and extraterrestrial habitats profoundly alter fluid dynamics, chemical reactions, and heat-mass transfer, leading to drastic changes in fire behavior. Understanding the solid material combustion under these conditions is vital for spacecraft fire safety and advances fundamental combustion science. This review synthesizes research on flame spread over solid materials under reduced buoyancy/gravity over the past half-century. It uniquely integrates the studies conducted in micro- and partial-gravities with ground-based experiments designed to mimic these environments. The review begins with the theoretical models defining the flame behavior and examines experimental findings from low gravities. These results reveal the important roles of “smothering” effects and radiative heat loss due to the suppressed natural convection, which drive a transition from two-dimensional to three-dimensional flame structures. Ground-based simulation methodologies, including reduced pressure environments and narrow channel apparatus, are critically examined for their ability to replicate low gravities. Stagnation point low-stretch diffusion flames are also included as a ground-based method to simulate the reduced-buoyancy effects on the spreading flame front from a more microscopic perspective. By comparing actual low-gravity data with simulated environments, the review introduces key similarity laws but also discusses the limitations of these methods in fully capturing low-gravity combustion dynamics. As the first integrated review of this topic, this work provides essential insights for ensuring the fire safety of human space exploration in the decades to come.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"111 ","pages":"Article 101251"},"PeriodicalIF":37.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145128256","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 : 2025-06-11DOI: 10.1016/j.pecs.2025.101234
Fengshan Liu , Jérôme Yon , José Morán , Georgios Kelesidis , Felipe Escudero , Andrés Fuentes
The toxicity, climate impact, as well as the physical and chemical properties of ultra-fine soot particles emitted from combustion systems are strongly dependent on their size and morphology. Research attention has been paid in the last three decades to developing more accurate and capable methods to model soot particle coagulation in the presence of inception, surface growth, and oxidation, to predict particle size distribution as well as the detailed aggregate morphology of soot. While soot particle concentrations in hydrocarbon flames are primarily governed by soot kinetics, the morphology of soot particles is controlled by both soot kinetics and particle dynamics. Flame-generated soot particles are fractal aggregates formed by polydisperse and nearly spherical primary particles with a certain degree of overlapping. The properties of fractal aggregates, nanoparticle coagulation, and soot formation chemistry all play important roles in soot formation. This article reviews all these aspects but the focus is on recent progress in macro- and meso-scale modeling of soot particle aggregation in laminar sooting flames to avoid the complexities of turbulence. The reviewed macro-scale methods based on the population balance equation include the commonly used sectional methods and methods of moments. The main features of three recently developed state-of-the-art meso-scale methods, namely the event-driven Discrete Element Method, Monte Carlo Aggregation Code, and detailed stochastic population balance model are reviewed. To highlight the complexities of modeling the particle size distribution and detailed particle morphology without and with surface growth, numerical simulations of three test cases were conducted using the event-driven Discrete Element Method, the Monte Carlo Aggregation Code, and the two macro-scale methods. A detailed analysis of the results was presented to understand how different treatments of particle coagulation and surface growth in the two meso-scale methods affect the predicted particle size and morphology. The remaining challenges in modeling detailed soot particle morphology are outlined.
{"title":"Progress in multi-scale modeling of soot particle aggregation in laminar sooting flames","authors":"Fengshan Liu , Jérôme Yon , José Morán , Georgios Kelesidis , Felipe Escudero , Andrés Fuentes","doi":"10.1016/j.pecs.2025.101234","DOIUrl":"10.1016/j.pecs.2025.101234","url":null,"abstract":"<div><div>The toxicity, climate impact, as well as the physical and chemical properties of ultra-fine soot particles emitted from combustion systems are strongly dependent on their size and morphology. Research attention has been paid in the last three decades to developing more accurate and capable methods to model soot particle coagulation in the presence of inception, surface growth, and oxidation, to predict particle size distribution as well as the detailed aggregate morphology of soot. While soot particle concentrations in hydrocarbon flames are primarily governed by soot kinetics, the morphology of soot particles is controlled by both soot kinetics and particle dynamics. Flame-generated soot particles are fractal aggregates formed by polydisperse and nearly spherical primary particles with a certain degree of overlapping. The properties of fractal aggregates, nanoparticle coagulation, and soot formation chemistry all play important roles in soot formation. This article reviews all these aspects but the focus is on recent progress in macro- and meso-scale modeling of soot particle aggregation in laminar sooting flames to avoid the complexities of turbulence. The reviewed macro-scale methods based on the population balance equation include the commonly used sectional methods and methods of moments. The main features of three recently developed state-of-the-art meso-scale methods, namely the event-driven Discrete Element Method, Monte Carlo Aggregation Code, and detailed stochastic population balance model are reviewed. To highlight the complexities of modeling the particle size distribution and detailed particle morphology without and with surface growth, numerical simulations of three test cases were conducted using the event-driven Discrete Element Method, the Monte Carlo Aggregation Code, and the two macro-scale methods. A detailed analysis of the results was presented to understand how different treatments of particle coagulation and surface growth in the two meso-scale methods affect the predicted particle size and morphology. The remaining challenges in modeling detailed soot particle morphology are outlined.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"110 ","pages":"Article 101234"},"PeriodicalIF":32.0,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144262261","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 : 2025-06-05DOI: 10.1016/j.pecs.2025.101235
Kyle J. Daun , Jennifer P. Spinti
Growing awareness of the environmental and health impacts of unburned and partially pyrolyzed hydrocarbons emitted by flaring establishes a need for instrumentation that can quantify the performance of flares in terms of overall combustion efficiency (CE) as well as the destruction removal efficiency (DRE) of a particular species. Climate modelers and policymakers need CE estimates to calculate the overall contribution of flaring to global methane inventories, so they may understand how flare emissions impact climate change and develop science-informed regulations; regulators need tools for enforcing current and emerging rules governing flare DRE; flare operators need instrumentation to identify problematic operating conditions in real time; and combustion equipment manufacturers need to quantify improvements in CE/DRE realized through new flare tip designs.
This paper reviews the current state-of-the-art in instrumentation and techniques used for quantifying CE and DRE, with a focus on flaring in the oil and gas sector. The paper begins with an overview of flaring, followed by a discussion of the aspects of flaring that make this measurement so difficult to carry out. Techniques for measuring flare CE and DRE are then examined. The paper concludes with an outlook of future challenges and opportunities.
{"title":"Techniques for measuring flare combustion efficiency and destruction removal efficiency: A review","authors":"Kyle J. Daun , Jennifer P. Spinti","doi":"10.1016/j.pecs.2025.101235","DOIUrl":"10.1016/j.pecs.2025.101235","url":null,"abstract":"<div><div>Growing awareness of the environmental and health impacts of unburned and partially pyrolyzed hydrocarbons emitted by flaring establishes a need for instrumentation that can quantify the performance of flares in terms of overall combustion efficiency (CE) as well as the destruction removal efficiency (DRE) of a particular species. Climate modelers and policymakers need CE estimates to calculate the overall contribution of flaring to global methane inventories, so they may understand how flare emissions impact climate change and develop science-informed regulations; regulators need tools for enforcing current and emerging rules governing flare DRE; flare operators need instrumentation to identify problematic operating conditions in real time; and combustion equipment manufacturers need to quantify improvements in CE/DRE realized through new flare tip designs.</div><div>This paper reviews the current state-of-the-art in instrumentation and techniques used for quantifying CE and DRE, with a focus on flaring in the oil and gas sector. The paper begins with an overview of flaring, followed by a discussion of the aspects of flaring that make this measurement so difficult to carry out. Techniques for measuring flare CE and DRE are then examined. The paper concludes with an outlook of future challenges and opportunities.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"110 ","pages":"Article 101235"},"PeriodicalIF":32.0,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144222957","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}
Internal combustion (IC) engines have contributed to global economic development in industrialized societies. Hydrocarbon fuels used for fueling the IC engines need to be replaced by sustainable and eco-friendly origins that do not adversely impact the environment locally and globally. Electro-fuels (or E-fuels) and biofuels are essential to displace fossil fuels. They are primarily produced using renewable electricity and feedstocks, respectively, and represent an emerging class of carbon-neutral drop-in fuels for the transport sector, which are becoming increasingly important with every passing day globally and have an essential role in the ‘net-zero’ future. This paper comprehensively reviews the advancements in IC engines to become more efficient in taking the fuel property advantages of various E-fuels and biofuels in existing engines. The paper focuses on several fuels, among the most studied ones in the open literature in the last decade, since their adoption might depend on factors such as the local economic considerations, cultural contexts and the application itself, storability, power requirement, and government policies. The paper covers these fuels by briefly introducing their production pathways and properties. It then focuses on their engine use to meet the future tailpipe and greenhouse gas emissions norms. Challenges regarding the modelling of engines powered by E- or bio-fuels are also included. E-fuels offer a straightforward advantage even in engine-out emissions and after-exhaust emission control technologies. It represents an opportunity to limit GHG emissions. Moreover, the E−(or Bio-) fuels powered engines can cover the same operating range (or a larger one) with similar efficiency or greater than hydrocarbon fuels. However, using these fuels still remain challenging. Retrofitting existing engines for using E−(or Bio-) fuels depends on the cost of the fuel injection system for injecting the fuel into the combustion chamber. The transition from fossil fuels can be done using liquid fuels such as methanol, ethanol, etc., by blending them with conventional fuels. In the long run, methanol, hydrogen, and ammonia are expected to significantly decarbonize the transport sector globally.
{"title":"Future of internal combustion engines using sustainable, scalable, and storable E-fuels and biofuels for decarbonizing transport and enabling advanced combustion technologies","authors":"Avinash Kumar Agarwal , Christine Mounaïm-Rousselle , Pierre Brequigny , Atul Dhar , Camille Hespel , Chetankumar Patel , Dhananjay Kumar Srivastava , Ganesh Duraisamy , Luis Le Moyne , Nikhil Sharma , Nitin Labhasetwar , Paramvir Singh , Piyali Das , Pradipta Kumar Panigrahi , Pravesh Chandra Shukla , P. Sakthivel , S.Venkata Mohan , Snehasish Panigrahy , Swarnendu Sen , Hardikk Valera","doi":"10.1016/j.pecs.2025.101236","DOIUrl":"10.1016/j.pecs.2025.101236","url":null,"abstract":"<div><div>Internal combustion (IC) engines have contributed to global economic development in industrialized societies. Hydrocarbon fuels used for fueling the IC engines need to be replaced by sustainable and eco-friendly origins that do not adversely impact the environment locally and globally. Electro-fuels (or E-fuels) and biofuels are essential to displace fossil fuels. They are primarily produced using renewable electricity and feedstocks, respectively, and represent an emerging class of carbon-neutral drop-in fuels for the transport sector, which are becoming increasingly important with every passing day globally and have an essential role in the ‘net-zero’ future. This paper comprehensively reviews the advancements in IC engines to become more efficient in taking the fuel property advantages of various E-fuels and biofuels in existing engines. The paper focuses on several fuels, among the most studied ones in the open literature in the last decade, since their adoption might depend on factors such as the local economic considerations, cultural contexts and the application itself, storability, power requirement, and government policies. The paper covers these fuels by briefly introducing their production pathways and properties. It then focuses on their engine use to meet the future tailpipe and greenhouse gas emissions norms. Challenges regarding the modelling of engines powered by E- or bio-fuels are also included. E-fuels offer a straightforward advantage even in engine-out emissions and after-exhaust emission control technologies. It represents an opportunity to limit GHG emissions. Moreover, the E−(or Bio-) fuels powered engines can cover the same operating range (or a larger one) with similar efficiency or greater than hydrocarbon fuels. However, using these fuels still remain challenging. Retrofitting existing engines for using E−(or Bio-) fuels depends on the cost of the fuel injection system for injecting the fuel into the combustion chamber. The transition from fossil fuels can be done using liquid fuels such as methanol, ethanol, etc., by blending them with conventional fuels. In the long run, methanol, hydrogen, and ammonia are expected to significantly decarbonize the transport sector globally.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"110 ","pages":"Article 101236"},"PeriodicalIF":32.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212708","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 : 2025-04-30DOI: 10.1016/j.pecs.2025.101233
Handel A. Martinez–Sarache , Vitor C. Simões , João A.F. Altoé , Juan Jesús Rico , David Patiño , Waldir A. Bizzo
Fixed-bed combustion is the oldest and most flexible method for generating heat from solid fuels with diverse morphological characteristics. This approach consolidates countercurrent fixed-bed burners as the most employed technique for biomass combustion in small- and medium-scale installations. In recent decades, researchers worldwide have generated significant experimental evidence to decipher the complex mechanisms behind reaction front propagation using laboratory-scale burners, which simulate the conditions of fuel in industrial plants. Many experimental results are available in the scientific literature, and the consolidation and discussion of the most relevant data can be useful for better understanding the current state of the art and identifying knowledge gaps on the subject. This paper presents a systematic review of the available literature concerning experimental studies of biomass fixed-bed combustion in laboratory-scale reactors. The central discussion encompasses the definition of the parameters employed to characterize the reaction zone behaviour and their dependence on fuel properties and primary air conditions. The insights gained in this review were addressed to propose criteria for harnessing the abundant availability of agricultural residues as alternative fuels in grate-firing systems.
{"title":"Experimental research on the countercurrent fixed-bed combustion of biomass","authors":"Handel A. Martinez–Sarache , Vitor C. Simões , João A.F. Altoé , Juan Jesús Rico , David Patiño , Waldir A. Bizzo","doi":"10.1016/j.pecs.2025.101233","DOIUrl":"10.1016/j.pecs.2025.101233","url":null,"abstract":"<div><div>Fixed-bed combustion is the oldest and most flexible method for generating heat from solid fuels with diverse morphological characteristics. This approach consolidates countercurrent fixed-bed burners as the most employed technique for biomass combustion in small- and medium-scale installations. In recent decades, researchers worldwide have generated significant experimental evidence to decipher the complex mechanisms behind reaction front propagation using laboratory-scale burners, which simulate the conditions of fuel in industrial plants. Many experimental results are available in the scientific literature, and the consolidation and discussion of the most relevant data can be useful for better understanding the current state of the art and identifying knowledge gaps on the subject. This paper presents a systematic review of the available literature concerning experimental studies of biomass fixed-bed combustion in laboratory-scale reactors. The central discussion encompasses the definition of the parameters employed to characterize the reaction zone behaviour and their dependence on fuel properties and primary air conditions. The insights gained in this review were addressed to propose criteria for harnessing the abundant availability of agricultural residues as alternative fuels in grate-firing systems.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"109 ","pages":"Article 101233"},"PeriodicalIF":32.0,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891922","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 : 2025-03-21DOI: 10.1016/j.pecs.2025.101218
Vishnu Hariharan , Mahesh S , Debi Prasad Mishra
The gaseous Inverse Jet Diffusion Flame (IJDF) is a unique nonpremixed flame that can be established in a simple coaxial burner when central air jet surrounded by annular fuel jet is ignited. The active research on laminar IJDF was initiated in the early 1980's, with a primary focus on its sooting characteristics. The soot formation, evolution and morphology in inverse jet diffusion flame differ fundamentally from that of the normal jet diffusion flame (NJDF) due to its distinct reactant delivery mode and fluid dynamics. The unique feature of the IJDF configuration is its reduced soot formation as compared to the NJDF configuration, particularly at higher air-fuel velocity ratio, even for hydrocarbon fuels. The literature has reported six types of laminar IJDF based on visual appearance and air-fuel velocity ratio. Furthermore, laminar IJDF is mainly utilized as a lab-scale flame by various researchers for the fundamental investigation of soot evolution in nonpremixed flames. Unlike normal jet diffusion flame, which is established with the fuel jet enveloped by an oxidizer jet, the post-flame emissions and the flame stability aspects of turbulent IJDF are relatively less understood. From a global perspective, coherence in the research on inverse jet diffusion flame is lacking and there is a need for an extensive investigation to understand this special type of nonpremixed flame. The present review identifies different emerging areas related to IJDF that the combustion researchers can pursue in the future.
Various aspects of laminar and turbulent IJDF, such as flame structure, soot formation, flame height, flame stability, thermal and emission characteristics are discussed in this review. This review may serve as a reference that contributes to the research perspectives on laminar and turbulent inverse jet diffusion flames for adapting the favourable aspects of this flame configuration in a wide range of industrial and domestic applications.
{"title":"The inverse jet diffusion flames: A systematic review","authors":"Vishnu Hariharan , Mahesh S , Debi Prasad Mishra","doi":"10.1016/j.pecs.2025.101218","DOIUrl":"10.1016/j.pecs.2025.101218","url":null,"abstract":"<div><div>The gaseous Inverse Jet Diffusion Flame (IJDF) is a unique nonpremixed flame that can be established in a simple coaxial burner when central air jet surrounded by annular fuel jet is ignited. The active research on laminar IJDF was initiated in the early 1980's, with a primary focus on its sooting characteristics. The soot formation, evolution and morphology in inverse jet diffusion flame differ fundamentally from that of the normal jet diffusion flame (NJDF) due to its distinct reactant delivery mode and fluid dynamics. The unique feature of the IJDF configuration is its reduced soot formation as compared to the NJDF configuration, particularly at higher air-fuel velocity ratio, even for hydrocarbon fuels. The literature has reported six types of laminar IJDF based on visual appearance and air-fuel velocity ratio. Furthermore, laminar IJDF is mainly utilized as a lab-scale flame by various researchers for the fundamental investigation of soot evolution in nonpremixed flames. Unlike normal jet diffusion flame, which is established with the fuel jet enveloped by an oxidizer jet, the post-flame emissions and the flame stability aspects of turbulent IJDF are relatively less understood. From a global perspective, coherence in the research on inverse jet diffusion flame is lacking and there is a need for an extensive investigation to understand this special type of nonpremixed flame. The present review identifies different emerging areas related to IJDF that the combustion researchers can pursue in the future.</div><div>Various aspects of laminar and turbulent IJDF, such as flame structure, soot formation, flame height, flame stability, thermal and emission characteristics are discussed in this review. This review may serve as a reference that contributes to the research perspectives on laminar and turbulent inverse jet diffusion flames for adapting the favourable aspects of this flame configuration in a wide range of industrial and domestic applications.</div></div>","PeriodicalId":410,"journal":{"name":"Progress in Energy and Combustion Science","volume":"109 ","pages":"Article 101218"},"PeriodicalIF":32.0,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682375","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}
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