Pub Date : 2026-01-07DOI: 10.1016/j.enconman.2025.121021
Mehrdad Raeesi , Amir Ansari Laleh , Mohammad Hassan Shojaeefard , Parinaz Chavoshnia
Electric vehicles are promoted as a sustainable alternative to gasoline-powered vehicles, yet their real-world effectiveness remains a subject of debate. The combined effects of battery aging and varied urban driving patterns on overall vehicle performance are not fully understood, representing a critical knowledge gap. It is hypothesized that battery degradation significantly reduces driving range and thermal stability, while the environmental and economic benefits depend strongly on electricity sources and usage conditions. To test this, a dynamic model was developed to simulate a new (100% state of health) and an aged (80% state of health) battery across four real-world Tehran driving cycles and the Worldwide Harmonized Light Vehicles Test Cycle. Results showed that driving range varied from 329 to 524 km, battery temperature in aged batteries reached 43.5 ℃ during fast charging (pack-average temperature), greenhouse gas emissions were reduced by over 80 percent with clean electricity though fine particle emissions could exceed those of gasoline vehicles with fossil-fuel grids and the per-kilometer cost was up to 25 percent lower despite a higher total cost of ownership. These findings highlight that the full benefits of electric vehicles are only realized when coupled with a clean electricity mix and supportive purchase policies.
{"title":"Quantifying the impact of battery degradation and urban driving dynamics on the life cycle performance of electric vehicles: an energy, thermal, environmental, and economic analysis","authors":"Mehrdad Raeesi , Amir Ansari Laleh , Mohammad Hassan Shojaeefard , Parinaz Chavoshnia","doi":"10.1016/j.enconman.2025.121021","DOIUrl":"10.1016/j.enconman.2025.121021","url":null,"abstract":"<div><div>Electric vehicles are promoted as a sustainable alternative to gasoline-powered vehicles, yet their real-world effectiveness remains a subject of debate. The combined effects of battery aging and varied urban driving patterns on overall vehicle performance are not fully understood, representing a critical knowledge gap. It is hypothesized that battery degradation significantly reduces driving range and thermal stability, while the environmental and economic benefits depend strongly on electricity sources and usage conditions. To test this, a dynamic model was developed to simulate a new (100% state of health) and an aged (80% state of health) battery across four real-world Tehran driving cycles and the Worldwide Harmonized Light Vehicles Test Cycle. Results showed that driving range varied from 329 to 524 km, battery temperature in aged batteries reached 43.5 ℃ during fast charging (pack-average temperature), greenhouse gas emissions were reduced by over 80 percent with clean electricity though fine particle emissions could exceed those of gasoline vehicles with fossil-fuel grids and the per-kilometer cost was up to 25 percent lower despite a higher total cost of ownership. These findings highlight that the full benefits of electric vehicles are only realized when coupled with a clean electricity mix and supportive purchase policies.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121021"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922734","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 : 2026-01-07DOI: 10.1016/j.enconman.2025.120977
Fan Jia , Xiang Yin , Anci Wang , Xu Han , Bin Chen , Feng Cao , Xiaolin Wang
With the rapid adoption of electric vehicles, electric vehicle thermal management systems (EVTMS) face pressing challenges in dynamic battery temperature uniformity control and coupling with the passenger compartment. Based on the vehicle thermal demands, a transient model of the EVTMS that uses refrigerant direct cooling for the battery was developed and validated. The dynamic cooling performance and cell-to-cell temperature uniformity of two system architectures with unequal evaporation pressure (UEP) and equal evaporation pressure (EEP) were compared under different control schemes. The suitability of each architecture and control approach was then analyzed. The performance degradation caused by branch mixing under fixed constraints and the corresponding mechanisms are elucidated. Furthermore, the trade-off between battery cooling and cabin thermal management was characterized, and the extent of the mutual influence was quantified. To address branch mixing-induced performance degradation and the trade-off between battery uniformity and cabin comfort, a novel semi-series direct cooling architecture with a temperature following control strategy is proposed. Simulation results indicate that this approach can reduce the battery’s maximum temperature difference by 60%, lower average power consumption by 3%, and maintain cabin comfort. The findings offer new theoretical and methodological guidance for co-optimizing architecture and control in CO2 direct cooling EVTMS for engineering applications.
{"title":"Dynamic trade-off balancing and energy savings in battery-cabin coupled CO2 EVTMS via semi-series refrigerant direct cooling architecture","authors":"Fan Jia , Xiang Yin , Anci Wang , Xu Han , Bin Chen , Feng Cao , Xiaolin Wang","doi":"10.1016/j.enconman.2025.120977","DOIUrl":"10.1016/j.enconman.2025.120977","url":null,"abstract":"<div><div>With the rapid adoption of electric vehicles, electric vehicle thermal management systems (EVTMS) face pressing challenges in dynamic battery temperature uniformity control and coupling with the passenger compartment. Based on the vehicle thermal demands, a transient model of the EVTMS that uses refrigerant direct cooling for the battery was developed and validated. The dynamic cooling performance and cell-to-cell temperature uniformity of two system architectures with unequal evaporation pressure (UEP) and equal evaporation pressure (EEP) were compared under different control schemes. The suitability of each architecture and control approach was then analyzed. The performance degradation caused by branch mixing under fixed constraints and the corresponding mechanisms are elucidated. Furthermore, the trade-off between battery cooling and cabin thermal management was characterized, and the extent of the mutual influence was quantified. To address branch mixing-induced performance degradation and the trade-off between battery uniformity and cabin comfort, a novel semi-series direct cooling architecture with a temperature following control strategy is proposed. Simulation results indicate that this approach can reduce the battery’s maximum temperature difference by 60%, lower average power consumption by 3%, and maintain cabin comfort. The findings offer new theoretical and methodological guidance for co-optimizing architecture and control in CO<sub>2</sub> direct cooling EVTMS for engineering applications.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 120977"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922692","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 : 2026-01-07DOI: 10.1016/j.enconman.2026.121033
Yuting Huang , Guangcai Gong , Jiaqing Liu , Xiang Chen
Radiant heating and cooling systems integrating active terminals with building envelopes offer high thermal comfort potential; however, the transient complementarity between active radiate terminals and passive building envelopes remains insufficiently quantified. This study aims to clarify how dynamic energy transmission mechanisms between air-carrying energy radiant terminals and building envelopes jointly influence indoor thermal environment and thermal comfort. Dynamic heating and cooling experiments were conducted for three terminal configurations (sidewall, ceiling, and composite walls), and a novel energy transfer decoupling model was developed to separately characterize heat exchange among the building envelope, occupied zone, and energy storage zone, accounting for radiation, convection, conduction, and air diffusion. In addition, a complementary model based on regression analysis and principal component analysis was established to quantify the relative influence of envelope surface temperatures on indoor air temperature and predicted mean vote (PMV). The proposed decoupling model predicts indoor air temperature with high accuracy (error < ±0.5 °C). The composite walls exhibited the fastest response (heating rate: 12.9 °C/h for air and about 16–9 °C/h for envelopes; cooling rate: 7.4 °C/h for air and about 6–8 °C/h for envelopes) with vertical temperature differences ≤ 0.3 °C in summer and ≤ 1.5 °C in winter, achieving thermal neutrality within 25 min. Radiative heat transfer dominated in the ceiling terminal, accounting for 68 % in winter and 50 % in summer. The complementary model further reveals that radiant surface temperatures exert a stronger influence on thermal comfort in heating than in cooling conditions. These findings provide quantitative insights into the synergistic interaction between radiant terminals and building envelopes, offering practical guidance for optimizing terminal design and improving energy efficiency in buildings.
{"title":"Transient energy transmission and thermal comfort complementarity characters between the air conditioning radiate terminal and envelopes","authors":"Yuting Huang , Guangcai Gong , Jiaqing Liu , Xiang Chen","doi":"10.1016/j.enconman.2026.121033","DOIUrl":"10.1016/j.enconman.2026.121033","url":null,"abstract":"<div><div>Radiant heating and cooling systems integrating active terminals with building envelopes offer high thermal comfort potential; however, the transient complementarity between active radiate terminals and passive building envelopes remains insufficiently quantified. This study aims to clarify how dynamic energy transmission mechanisms between air-carrying energy radiant terminals and building envelopes jointly influence indoor thermal environment and thermal comfort. Dynamic heating and cooling experiments were conducted for three terminal configurations (sidewall, ceiling, and composite walls), and a novel energy transfer decoupling model was developed to separately characterize heat exchange among the building envelope, occupied zone, and energy storage zone, accounting for radiation, convection, conduction, and air diffusion. In addition, a complementary model based on regression analysis and principal component analysis was established to quantify the relative influence of envelope surface temperatures on indoor air temperature and predicted mean vote (PMV). The proposed decoupling model predicts indoor air temperature with high accuracy (error < ±0.5 °C). The composite walls exhibited the fastest response (heating rate: 12.9 °C/h for air and about 16–9 °C/h for envelopes; cooling rate: 7.4 °C/h for air and about 6–8 °C/h for envelopes) with vertical temperature differences ≤ 0.3 °C in summer and ≤ 1.5 °C in winter, achieving thermal neutrality within 25 min. Radiative heat transfer dominated in the ceiling terminal, accounting for 68 % in winter and 50 % in summer. The complementary model further reveals that radiant surface temperatures exert a stronger influence on thermal comfort in heating than in cooling conditions. These findings provide quantitative insights into the synergistic interaction between radiant terminals and building envelopes, offering practical guidance for optimizing terminal design and improving energy efficiency in buildings.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121033"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922693","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 : 2026-01-07DOI: 10.1016/j.enconman.2025.121003
Aaron S. Jajjawi , Henrik Wenzel , Freia Harzendorf , Jann M. Weinand , Detlef Stolten , Ralf Peters
Adsorption-based Direct Air Capture (DAC) is crucial for achieving negative emissions but faces significant challenges due to high energy demand and operational costs. While recent research has highlighted that weather conditions significantly affect DAC energy demand and cost, current DAC systems are typically optimized under steady-state conditions, overlooking the impact of ambient weather variability on the optimal operating point. This study addresses that gap by investigating whether dynamically adjusted adsorption and desorption durations based on hourly weather conditions can improve energy efficiency compared to static operation. Therefore, a process model incorporating co-adsorption effects was optimized for real-world weather conditions and the results are utilized as an input for a techno-economic assessment. Dynamic operation of the optimized process model was evaluated using hourly weather data from four possible DAC locations, revealing potential reductions in electrical and thermal energy demands of up to 8.8 % and 0.9 %, respectively. Additional analyses show that simplified day–night and seasonal operating strategies achieve nearly the same energy savings as hourly adaptation, substantially reducing control complexity. Integration of the optimized process model into a techno-economic assessment reveals weather-driven cost variations of up to 72 €/tCO2 and demonstrates strong sensitivity of DAC costs to renewable energy intermittency. By providing detailed data on the optimized process model, including energy consumption and productivity across diverse climatic conditions, the study supports more refined and location-specific future assessments.
{"title":"Weather-dependent direct air capture process modeling for techno-economic assessments","authors":"Aaron S. Jajjawi , Henrik Wenzel , Freia Harzendorf , Jann M. Weinand , Detlef Stolten , Ralf Peters","doi":"10.1016/j.enconman.2025.121003","DOIUrl":"10.1016/j.enconman.2025.121003","url":null,"abstract":"<div><div>Adsorption-based Direct Air Capture (DAC) is crucial for achieving negative emissions but faces significant challenges due to high energy demand and operational costs. While recent research has highlighted that weather conditions significantly affect DAC energy demand and cost, current DAC systems are typically optimized under steady-state conditions, overlooking the impact of ambient weather variability on the optimal operating point. This study addresses that gap by investigating whether dynamically adjusted adsorption and desorption durations based on hourly weather conditions can improve energy efficiency compared to static operation. Therefore, a process model incorporating co-adsorption effects was optimized for real-world weather conditions and the results are utilized as an input for a techno-economic assessment. Dynamic operation of the optimized process model was evaluated using hourly weather data from four possible DAC locations, revealing potential reductions in electrical and thermal energy demands of up to 8.8 % and 0.9 %, respectively. Additional analyses show that simplified day–night and seasonal operating strategies achieve nearly the same energy savings as hourly adaptation, substantially reducing control complexity. Integration of the optimized process model into a techno-economic assessment reveals weather-driven cost variations of up to 72 €/t<sub>CO2</sub> and demonstrates strong sensitivity of DAC costs to renewable energy intermittency. By providing detailed data on the optimized process model, including energy consumption and productivity across diverse climatic conditions, the study supports more refined and location-specific future assessments.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121003"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922801","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}
To address the utilization of environmentally friendly refrigerants and enhance the driving range of electric vehicles, this paper proposes an optimal performance prediction model for CO2 heat pump air conditioning systems in electric vehicles, which is based on the integration of artificial neural networks and genetic algorithms(ANN-GA). Aiming at the long-standing limitations of conventional control strategies under multivariable coupling and highly dynamic operating conditions—particularly the insufficient optimization of energy efficiency and slow dynamic response—this work systematically investigates, through combined experimental and numerical analyses, the influence mechanisms of key operating parameters on system performance and the optimal discharge pressure. By revealing the strong nonlinear relationship between discharge pressure and system coefficient of performance (COP) under varying ambient and load conditions, the control objective of dynamically regulating the discharge pressure to maximize COP is explicitly established. An adaptive control strategy based on ANN-GA is innovatively adopted to realize the online/offline optimization of the optimal discharge pressure,thereby filling the research gap in intelligent, self-adaptive optimization of transcritical CO2 heat pump systems for electric vehicles. The results show that this ANN-GA strategy, compared with the traditional fixed discharge pressure PI control, significantly improves the energy efficiency in both summer and winter dynamic conditions, with energy savings of 17.5 % in refrigeration conditions and 11.17 % in heating conditions. Furthermore, it is demonstrated that the system can quickly achieve the target cabin temperature and accurately control the fluctuation within ±1.0 °C, indicating excellent thermal comfort control performance. This study confirms that the proposed ANN–GA-based strategy provides an efficient, intelligent, and robust solution for improving both the energy efficiency and thermal comfort of CO2 heat pump air-conditioning systems in electric vehicles, and offers a new technical pathway for the intelligent control of next-generation automotive thermal management systems.
{"title":"Research on adaptive control strategy for CO2 heat pump air conditioning system of electric vehicles based on artificial neural network and genetic algorithm","authors":"Zhuo Liu, Haiping Wang, Xiaopeng Wang, Hongli Xu, Bowen Zhang, Qingsong Wang, Hongxia Zhao","doi":"10.1016/j.enconman.2025.121008","DOIUrl":"10.1016/j.enconman.2025.121008","url":null,"abstract":"<div><div>To address the utilization of environmentally friendly refrigerants and enhance the driving range of electric vehicles, this paper proposes an optimal performance prediction model for CO<sub>2</sub> heat pump air conditioning systems in electric vehicles, which is based on the integration of artificial neural networks and genetic algorithms(ANN-GA). Aiming at the long-standing limitations of conventional control strategies under multivariable coupling and highly dynamic operating conditions—particularly the insufficient optimization of energy efficiency and slow dynamic response—this work systematically investigates, through combined experimental and numerical analyses, the influence mechanisms of key operating parameters on system performance and the optimal discharge pressure. By revealing the strong nonlinear relationship between discharge pressure and system coefficient of performance (COP) under varying ambient and load conditions, the control objective of dynamically regulating the discharge pressure to maximize COP is explicitly established. An adaptive control strategy based on ANN-GA is innovatively adopted to realize the online/offline optimization of the optimal discharge pressure,thereby filling the research gap in intelligent, self-adaptive optimization of transcritical CO<sub>2</sub> heat pump systems for electric vehicles. The results show that this ANN-GA strategy, compared with the traditional fixed discharge pressure PI control, significantly improves the energy efficiency in both summer and winter dynamic conditions, with energy savings of 17.5 % in refrigeration conditions and 11.17 % in heating conditions. Furthermore, it is demonstrated that the system can quickly achieve the target cabin temperature and accurately control the fluctuation within ±1.0 °C, indicating excellent thermal comfort control performance. This study confirms that the proposed ANN–GA-based strategy provides an efficient, intelligent, and robust solution for improving both the energy efficiency and thermal comfort of CO<sub>2</sub> heat pump air-conditioning systems in electric vehicles, and offers a new technical pathway for the intelligent control of next-generation automotive thermal management systems.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121008"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922814","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 : 2026-01-07DOI: 10.1016/j.enconman.2026.121032
M.A.M. Ahmed , Muhammad H. Elbassoussi , Syed M. Zubair
This study presents a simplified, dimensionless, and second-law-compliant analytical model for balanced humidification–dehumidification desalination systems. By applying rigorous dimensionless analysis, the proposed model successfully reduces input parameters without compromising thermodynamic accuracy or predictive performance. The developed formulation eliminates nonphysical behavior, such as the emergence of multiple real roots that violate the second law of thermodynamics, through the introduction of explicit constraints and critical thresholds for enthalpy pinch and temperature. A key outcome of the analysis is the identification of a dimensionless dehumidifier slope that governs system behavior and inherently accounts for maximum temperature effects via normalized parameters. The model offers analytical insight into the relationship between air and water temperature profiles, enthalpy pinch, and thermal efficiency, thus simplifying the overall optimization process. The model is validated against the conventional numerical model for critical enthalpy pinch, gain output ratio, optimal mass flowrate ratio, and recovery ratio, achieving close agreement across a wide range of operating conditions. Case study results demonstrate the model’s practical utility, predicting a GOR of 2.27 at minimal thermal input with recovery ratio of 3.60 %. The proposed framework offers a scalable and thermodynamically consistent tool for humidification-dehumidification systems optimization and operational planning.
{"title":"A dimensionless second-law-compliant integrated model for balanced humidification-dehumidification systems","authors":"M.A.M. Ahmed , Muhammad H. Elbassoussi , Syed M. Zubair","doi":"10.1016/j.enconman.2026.121032","DOIUrl":"10.1016/j.enconman.2026.121032","url":null,"abstract":"<div><div>This study presents a simplified, dimensionless, and second-law-compliant analytical model for balanced humidification–dehumidification desalination systems. By applying rigorous dimensionless analysis, the proposed model successfully reduces input parameters without compromising thermodynamic accuracy or predictive performance. The developed formulation eliminates nonphysical behavior, such as the emergence of multiple real roots that violate the second law of thermodynamics, through the introduction of explicit constraints and critical thresholds for enthalpy pinch and temperature. A key outcome of the analysis is the identification of a dimensionless dehumidifier slope that governs system behavior and inherently accounts for maximum temperature effects via normalized parameters. The model offers analytical insight into the relationship between air and water temperature profiles, enthalpy pinch, and thermal efficiency, thus simplifying the overall optimization process. The model is validated against the conventional numerical model for critical enthalpy pinch, gain output ratio, optimal mass flowrate ratio, and recovery ratio, achieving close agreement across a wide range of operating conditions. Case study results demonstrate the model’s practical utility, predicting a GOR of 2.27 at minimal thermal input with recovery ratio of 3.60 %. The proposed framework offers a scalable and thermodynamically consistent tool for humidification-dehumidification systems optimization and operational planning.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121032"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922804","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 : 2026-01-07DOI: 10.1016/j.enconman.2025.121029
Haotian Liu, Hailong Lu
The inflow of boundary methane-undersaturated water can trigger hydrate dissolution by creating a gradient of methane concentration near hydrate surfaces. However, the existing model cannot account for hydrate dissolution and dissociation at the same time on a macroscopic scale. In this study, building on the mass conservation of methane, a one-dimensional radial flow model is derived to simultaneously consider these two mechanisms based on the assumptions of steady-state and isothermal flow. By nondimensionalizing the model, five key decisive dimensionless numbers are identified as governing the dynamic of hydrate decrease. For the South China Sea hydrate reservoir, water flow causes ∼26.7 % of gas hydrate to be consumed through dissolution, yet retards hydrate dissociation through methane compensation. After analyzing the partial derivative of each dimensionless number vs the convergence radius where hydrate dissociation front and dissolution front intersect, a general radius form is derived by integrating dimensionless number-radius trends and determined via nonlinear least-squares regression. These results not only indicate that boundary water plays a pivotal role in hydrate exploitation but also provide a formula to enable rapid quantitative estimation of hydrate breakdown modes during its exploitation, yielding critical insights for environmental applications including CO2 storage via hydrate.
{"title":"Hydrate dissolution induced by methane-undersaturated boundary water in hydrate exploitation: Model derivation and its solution","authors":"Haotian Liu, Hailong Lu","doi":"10.1016/j.enconman.2025.121029","DOIUrl":"10.1016/j.enconman.2025.121029","url":null,"abstract":"<div><div>The inflow of boundary methane-undersaturated water can trigger hydrate dissolution by creating a gradient of methane concentration near hydrate surfaces. However, the existing model cannot account for hydrate dissolution and dissociation at the same time on a macroscopic scale. In this study, building on the mass conservation of methane, a one-dimensional radial flow model is derived to simultaneously consider these two mechanisms based on the assumptions of steady-state and isothermal flow. By nondimensionalizing the model, five key decisive dimensionless numbers are identified as governing the dynamic of hydrate decrease. For the South China Sea hydrate reservoir, water flow causes ∼26.7 % of gas hydrate to be consumed through dissolution, yet retards hydrate dissociation through methane compensation. After analyzing the partial derivative of each dimensionless number <em>vs</em> the convergence radius where hydrate dissociation front and dissolution front intersect, a general radius form is derived by integrating dimensionless number-radius trends and determined <em>via</em> nonlinear least-squares regression. These results not only indicate that boundary water plays a pivotal role in hydrate exploitation but also provide a formula to enable rapid quantitative estimation of hydrate breakdown modes during its exploitation, yielding critical insights for environmental applications including CO<sub>2</sub> storage <em>via</em> hydrate.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121029"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922813","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}
The safe storage of renewable biomass in piles poses a significant challenge. Low-temperature oxidation, water evaporation or condensation, and the metabolic processes of microorganisms occur simultaneously within open-air biomass piles, leading to intense self-heating. Drawing on our knowledge of Computational Fluid Dynamics (CFD) simulation, we successfully integrated the three mechanisms of biomass pile heating in the present work. This study examined moisture migration and temperature changes in a woodchip storage pile over a simulated 3-month period. We focused on enhancing the mathematical model of water migration, developing a method sensitive to environmental humidity, and adding a correction factor to match the experimentally measured water migration rate. Based on the above simulation framework, this study investigated the effects of changes in pile height, particle diameter, ambient humidity, and temperature on self-heating. Finally, a preliminary investigation was conducted on the safety margins that can prevent spontaneous ignition of woodchip storage piles under certain extreme weather conditions. The results indicate that during the self-heating process of a woodchip storage pile, the highest temperature inside the pile differs from the experimental record by only 3 to 4 °C, and the duration of the elevated temperature differs by about 2 days. When the correction factor is 0.5, the moisture migration process within the pile better matches the experimental data. The dry matter loss of the biomass is approximately 11 %, slightly higher than the 9 % in the experimental record. Reducing the pile height, increasing particle size, and maintaining lower ambient temperature and humidity are all beneficial for safe storage. Finally, a safety margin to prevent woodchip pile spontaneous ignition is proposed: when the pile height is 6 m, the particle size should not be less than 3 cm; when the stack height is 3.5 m, the particle size should not be less than 2 cm. This long-term simulation of biomass storage piles provides significant input for the safety of biomass storage, as it accurately predicts temperature variation and moisture migration.
{"title":"Modelling of self-heating in open-air woodchip storage piles: an ambient humidity-sensitive approach to predict moisture migration and temperature dynamics","authors":"Yonghao Wang , Matthias Mandø , Ralf Pecenka , Chungen Yin","doi":"10.1016/j.enconman.2026.121034","DOIUrl":"10.1016/j.enconman.2026.121034","url":null,"abstract":"<div><div>The safe storage of renewable biomass in piles poses a significant challenge. Low-temperature oxidation, water evaporation or condensation, and the metabolic processes of microorganisms occur simultaneously within open-air biomass piles, leading to intense self-heating. Drawing on our knowledge of Computational Fluid Dynamics (CFD) simulation, we successfully integrated the three mechanisms of biomass pile heating in the present work. This study examined moisture migration and temperature changes in a woodchip storage pile over a simulated 3-month period. We focused on enhancing the mathematical model of water migration, developing a method sensitive to environmental humidity, and adding a correction factor to match the experimentally measured water migration rate. Based on the above simulation framework, this study investigated the effects of changes in pile height, particle diameter, ambient humidity, and temperature on self-heating. Finally, a preliminary investigation was conducted on the safety margins that can prevent spontaneous ignition of woodchip storage piles under certain extreme weather conditions. The results indicate that during the self-heating process of a woodchip storage pile, the highest temperature inside the pile differs from the experimental record by only 3 to 4 °C, and the duration of the elevated temperature differs by about 2 days. When the correction factor <span><math><mi>φ</mi></math></span> is 0.5, the moisture migration process within the pile better matches the experimental data. The dry matter loss of the biomass is approximately 11 %, slightly higher than the 9 % in the experimental record. Reducing the pile height, increasing particle size, and maintaining lower ambient temperature and humidity are all beneficial for safe storage. Finally, a safety margin to prevent woodchip pile spontaneous ignition is proposed: when the pile height is 6 m, the particle size should not be less than 3 cm; when the stack height is 3.5 m, the particle size should not be less than 2 cm. This long-term simulation of biomass storage piles provides significant input for the safety of biomass storage, as it accurately predicts temperature variation and moisture migration.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121034"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922689","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 : 2026-01-07DOI: 10.1016/j.enconman.2026.121048
Tiantian Wang , Xuemin Liu , Juan Li , Yang Zhang
In the ironmaking process, replacing coke with hydrogen-enriched gas is an effective approach to reducing carbon emissions and enhancing the energy efficiency of the blast furnace. In the meantime, using the exhaust gas from the blast furnace and coke oven for heating and power generation through gas-fired boilers can further promote energy conservation and emission reduction. Under this circumstance, the present study focused on the effect of variation in fuel components on the environmental and efficiency of gas-fired boilers based on the hydrogen-rich ironmaking process. The variation of blast furnace gas (BFG) components discharged from the blast furnace with the injection of hydrogen-enriched gas, i.e., the mixture of coke oven gas (COG) and green hydrogen, was first discussed. Then, taking a 110 t/h BFG-fired boiler as an example, when respectively using BFG and BFG-COG-H2 (the mixture of BFG, COG, and H2) as fuel to maintain a constant boiler evaporation rate and excess air ratio, the comprehensive boiler performances in terms of thermodynamic characteristics, decarbonization potential, and NOx emissions were investigated by the combined thermodynamic, heat transfer, and chemical reaction network models. The results show that as the H2 content increases by ∼65 % and the CO content decreases by ∼23 % in BFG, the decarbonization potential improves by 19.1 %, the boiler thermal efficiency increases by 1.4 % from 90.93 % to 92.18 %, and NOx emissions also rise by 7.9 % from 23.02 mg/m3 to 24.83 mg/m3. After blending BFG with COG-H2, the decarbonization potential of the boiler will be further improved by over 30 %. As the H2 content increases by ∼66 % and the CO content decreases by ∼28 % in BFG-COG-H2, the decarbonization potential improves by 11.8 %, the boiler thermal efficiency decreases by 0.2 % from 93.57 % to 93.40 %, and NOx emissions also decline by 9.7 % from 40.75 mg/m3 to 36.78 mg/m3. There exists a trade-off between increasing boiler thermal efficiency and decreasing NOx emissions.
{"title":"Environmental and efficiency evaluation of blast furnace gas-fired boiler based on hydrogen-rich ironmaking process","authors":"Tiantian Wang , Xuemin Liu , Juan Li , Yang Zhang","doi":"10.1016/j.enconman.2026.121048","DOIUrl":"10.1016/j.enconman.2026.121048","url":null,"abstract":"<div><div>In the ironmaking process, replacing coke with hydrogen-enriched gas is an effective approach to reducing carbon emissions and enhancing the energy efficiency of the blast furnace. In the meantime, using the exhaust gas from the blast furnace and coke oven for heating and power generation through gas-fired boilers can further promote energy conservation and emission reduction. Under this circumstance, the present study focused on the effect of variation in fuel components on the environmental and efficiency of gas-fired boilers based on the hydrogen-rich ironmaking process. The variation of blast furnace gas (BFG) components discharged from the blast furnace with the injection of hydrogen-enriched gas, <em>i.e.</em>, the mixture of coke oven gas (COG) and green hydrogen, was first discussed. Then, taking a 110 t/h BFG-fired boiler as an example, when respectively using BFG and BFG-COG-H<sub>2</sub> (the mixture of BFG, COG, and H<sub>2</sub>) as fuel to maintain a constant boiler evaporation rate and excess air ratio, the comprehensive boiler performances in terms of thermodynamic characteristics, decarbonization potential, and NOx emissions were investigated by the combined thermodynamic, heat transfer, and chemical reaction network models. The results show that as the H<sub>2</sub> content increases by ∼65 % and the CO content decreases by ∼23 % in BFG, the decarbonization potential improves by 19.1 %, the boiler thermal efficiency increases by 1.4 % from 90.93 % to 92.18 %, and NOx emissions also rise by 7.9 % from 23.02 mg/m<sup>3</sup> to 24.83 mg/m<sup>3</sup>. After blending BFG with COG-H<sub>2</sub>, the decarbonization potential of the boiler will be further improved by over 30 %. As the H<sub>2</sub> content increases by ∼66 % and the CO content decreases by ∼28 % in BFG-COG-H<sub>2</sub>, the decarbonization potential improves by 11.8 %, the boiler thermal efficiency decreases by 0.2 % from 93.57 % to 93.40 %, and NOx emissions also decline by 9.7 % from 40.75 mg/m<sup>3</sup> to 36.78 mg/m<sup>3</sup>. There exists a trade-off between increasing boiler thermal efficiency and decreasing NOx emissions.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121048"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922690","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}
Thermoelectric conversion is a promising clean way to generate electricity. To efficiently utilize the large temperature differences naturally found in plateau regions, it is urgent to develop novel and compatible thermoelectric conversion technologies. Here, a self-adaptive thermoelectric conversion strategy is reported for conditions involving day-night large temperature differences enabled by superior thermal management capacity of phase change brine gels (PCBGs) with high latent heat and high thermal conductivity. The segmental adsorption of cold-storage brine by agar and the porous adsorption by expanded graphite (EG) synergistically enable high brine loading in the gel, yielding enthalpy and enthalpy efficiency values of 261.79 J·g−1 and 93.75 %, respectively. PCBGs also demonstrate excellent leakage resistance and cyclic stability. Surface modification of EG with gallic acid produces an evenly distributed composite of phase change brine and EG, yielding a thermal conductivity of up to 5.212 W·m−1·K−1. PCBG is integrated with thermoelectric panel to form a self-adaptive thermoelectric conversion device. PCBGs take advantage of natural nighttime cooling to store cold, thereby providing a large temperature difference of 42°C for thermoelectric devices operating during the day. The output voltage and power reach 0.33 V and 14 mW, respectively. This work effectively mitigates the temperature impact of the plateau climate on thermoelectric devices, offering new insights into green power generation.
{"title":"Self-adaptive thermoelectric conversion under day-night large temperature differences enabled by superior thermal management capacity of phase change brine gels with high latent heat and high thermal conductivity","authors":"Zhenxiang Wang, Qianyu Zhou, Pengcheng Lin, Ying Chen","doi":"10.1016/j.enconman.2025.121015","DOIUrl":"10.1016/j.enconman.2025.121015","url":null,"abstract":"<div><div>Thermoelectric conversion is a promising clean way to generate electricity. To efficiently utilize the large temperature differences naturally found in plateau regions, it is urgent to develop novel and compatible thermoelectric conversion technologies. Here, a self-adaptive thermoelectric conversion strategy is reported for conditions involving day-night large temperature differences enabled by superior thermal management capacity of phase change brine gels (PCBGs) with high latent heat and high thermal conductivity. The segmental adsorption of cold-storage brine by agar and the porous adsorption by expanded graphite (EG) synergistically enable high brine loading in the gel, yielding enthalpy and enthalpy efficiency values of 261.79 J·g<sup>−1</sup> and 93.75 %, respectively. PCBGs also demonstrate excellent leakage resistance and cyclic stability. Surface modification of EG with gallic acid produces an evenly distributed composite of phase change brine and EG, yielding a thermal conductivity of up to 5.212 W·m<sup>−1</sup>·K<sup>−1</sup>. PCBG is integrated with thermoelectric panel to form a self-adaptive thermoelectric conversion device. PCBGs take advantage of natural nighttime cooling to store cold, thereby providing a large temperature difference of 42°C for thermoelectric devices operating during the day. The output voltage and power reach 0.33 V and 14 mW, respectively. This work effectively mitigates the temperature impact of the plateau climate on thermoelectric devices, offering new insights into green power generation.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121015"},"PeriodicalIF":10.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922728","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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