Pub Date : 2026-02-06DOI: 10.1016/j.energy.2026.140356
Huanbao Fan , Mengxiang Jiang , Lu Dang , Junxiao Feng
This study proposes and evaluates a dual-stage dispersed fuel injection strategy for a novel U-type radiant tube with internal/external flue gas self-recirculation. A comparative analysis was conducted on the flow structure, flame position, heat transfer characteristics, and overall performance of single-stage and dual-stage dispersed fuel injection modes utilizing a validated three-dimensional CFD combustion model. The influence mechanism of the secondary dispersed fuel fraction (χsec-disp, 5%–30%) on tube wall temperature uniformity and NOx emissions was specifically investigated. Results demonstrate that dual-stage dispersed combustion effectively compensates for the axial heat loss along the flow path, significantly elevating the temperature and expanding the high-temperature zone in the second straight tube, despite causing a slight increase in NOx. Increasing the χsec-disp from 5% to 30%, markedly enhanced tube wall temperature uniformity (maximum temperature difference reduced by 21.6%) and suppressed NOx generation and emission (outlet concentration as low as 49.6 mg/m3 @ 8% O2). These improvements stem primarily from the increased proportion of dispersed fuel, which promotes global fuel dispersion, mitigates localized flame concentration, and fosters more uniform combustion within the tube. Therefore, a moderate increase in χsec-disp proves effective in enhancing heating uniformity and reducing NOx emissions, offering pivotal guidance for the design optimization of next-generation radiant tubes.
{"title":"Numerical study on dispersed fuel injection strategies for thermal performance enhancement in a self-flue-recirculating radiant tube","authors":"Huanbao Fan , Mengxiang Jiang , Lu Dang , Junxiao Feng","doi":"10.1016/j.energy.2026.140356","DOIUrl":"10.1016/j.energy.2026.140356","url":null,"abstract":"<div><div>This study proposes and evaluates a dual-stage dispersed fuel injection strategy for a novel U-type radiant tube with internal/external flue gas self-recirculation. A comparative analysis was conducted on the flow structure, flame position, heat transfer characteristics, and overall performance of single-stage and dual-stage dispersed fuel injection modes utilizing a validated three-dimensional CFD combustion model. The influence mechanism of the secondary dispersed fuel fraction (<em>χ</em><sub>sec-disp</sub>, 5%–30%) on tube wall temperature uniformity and NOx emissions was specifically investigated. Results demonstrate that dual-stage dispersed combustion effectively compensates for the axial heat loss along the flow path, significantly elevating the temperature and expanding the high-temperature zone in the second straight tube, despite causing a slight increase in NOx. Increasing the <em>χ</em><sub>sec-disp</sub> from 5% to 30%, markedly enhanced tube wall temperature uniformity (maximum temperature difference reduced by 21.6%) and suppressed NOx generation and emission (outlet concentration as low as 49.6 mg/m<sup>3</sup> @ 8% O<sub>2</sub>). These improvements stem primarily from the increased proportion of dispersed fuel, which promotes global fuel dispersion, mitigates localized flame concentration, and fosters more uniform combustion within the tube. Therefore, a moderate increase in <em>χ</em><sub>sec-disp</sub> proves effective in enhancing heating uniformity and reducing NOx emissions, offering pivotal guidance for the design optimization of next-generation radiant tubes.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140356"},"PeriodicalIF":9.4,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187352","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 : 2026-02-06DOI: 10.1016/j.energy.2026.140147
Nanjiang Dong , Tao Zhang , Rui Wang
The day-ahead scheduling of an integrated energy system, which combines cooling, heating, and power generation alongside wind and photovoltaic energy sources, presents several challenges. These challenges stem from the presence of semi-continuous variables, multiple optimization objectives, nonlinearities, and various constraints. Existing multi-objective evolutionary algorithms, however, are not sufficiently efficient in solving the day-ahead scheduling model, particularly when dealing with semi-continuous variables. To address these issues, this paper proposed a novel multi-objective evolutionary algorithm based on a two-tier fully connected weight network. The model leverages a fully connected network to effectively address the semi-continuous variable problem, offering a unique solution to the complexities of day-ahead operation scheduling. The upper layer of the network employs multi-space dimensionality reduction to enhance global search capabilities, while the lower layer focuses on local search for more targeted solutions. Furthermore, the design of constraint repair operators is influenced by the structure of the algorithm, aiming to satisfy the constraints inherent in day-ahead scheduling and improve the efficiency of the search process. In experimental simulations, the proposed algorithm’s performance was compared with that of the latest constrained multi-objective optimization algorithms. The results demonstrate that the proposed algorithm significantly improves both optimization efficiency and the quality of the scheduling solutions. These findings highlight the effectiveness and superiority of the proposed algorithm in optimizing day-ahead scheduling for integrated energy systems.
{"title":"Multi-objective evolutionary algorithm with two-tier fully-connected weight network for day-ahead scheduling of integrated cooling, heating and power energy systems","authors":"Nanjiang Dong , Tao Zhang , Rui Wang","doi":"10.1016/j.energy.2026.140147","DOIUrl":"10.1016/j.energy.2026.140147","url":null,"abstract":"<div><div>The day-ahead scheduling of an integrated energy system, which combines cooling, heating, and power generation alongside wind and photovoltaic energy sources, presents several challenges. These challenges stem from the presence of semi-continuous variables, multiple optimization objectives, nonlinearities, and various constraints. Existing multi-objective evolutionary algorithms, however, are not sufficiently efficient in solving the day-ahead scheduling model, particularly when dealing with semi-continuous variables. To address these issues, this paper proposed a novel multi-objective evolutionary algorithm based on a two-tier fully connected weight network. The model leverages a fully connected network to effectively address the semi-continuous variable problem, offering a unique solution to the complexities of day-ahead operation scheduling. The upper layer of the network employs multi-space dimensionality reduction to enhance global search capabilities, while the lower layer focuses on local search for more targeted solutions. Furthermore, the design of constraint repair operators is influenced by the structure of the algorithm, aiming to satisfy the constraints inherent in day-ahead scheduling and improve the efficiency of the search process. In experimental simulations, the proposed algorithm’s performance was compared with that of the latest constrained multi-objective optimization algorithms. The results demonstrate that the proposed algorithm significantly improves both optimization efficiency and the quality of the scheduling solutions. These findings highlight the effectiveness and superiority of the proposed algorithm in optimizing day-ahead scheduling for integrated energy systems.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140147"},"PeriodicalIF":9.4,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187517","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 : 2026-02-06DOI: 10.1016/j.energy.2026.140352
Xiaocun Sun , Lingfeng Shi , Wei Lu , Hua Tian , Gequn Shu
CO2 is a promising natural working fluid for the combined cooling and power cycle (CCP) due to its great physical properties. Composition adjustment based on CO2-based zeotropic mixtures can further enhance the performance of CCP in changing external conditions (off-design performance). However, the enhancing effect of composition adjustment on CCP has only been proven effective in theoretical studies. Systematic experimental tests are lacking, and the operating feasibility of composition adjustment remains unrevealed. In this study, the off-design performance of composition-adjustable CCP is investigated. The performance comparison between composition-adjustable CCP and composition-fixed CCP is developed, and the dynamic characteristics of composition-adjustable CCP in off-design conditions are obtained. Experimental results show that composition adjustment can enhance the off-design performance of CCP, and the maximum relative increase can reach 13.7%. During the off-design conditions, the elapsed time of composition balance is significantly smaller than thermal balance, and the consuming time of composition adjustment can be ignored as long as the liquid level in separator is maintained steady. To accelerate the balancing speed of system, a fast regulation strategy based on flow reverse adjustment is proposed, and the elapsed time can be shortened by around half on the premise of maintaining the stabilization of system performance.
{"title":"Experiment on composition-adjustable combined cooling and power cycle with CO2-based zeotropic mixture: An off-design performance investigation","authors":"Xiaocun Sun , Lingfeng Shi , Wei Lu , Hua Tian , Gequn Shu","doi":"10.1016/j.energy.2026.140352","DOIUrl":"10.1016/j.energy.2026.140352","url":null,"abstract":"<div><div>CO<sub>2</sub> is a promising natural working fluid for the combined cooling and power cycle (CCP) due to its great physical properties. Composition adjustment based on CO<sub>2</sub>-based zeotropic mixtures can further enhance the performance of CCP in changing external conditions (off-design performance). However, the enhancing effect of composition adjustment on CCP has only been proven effective in theoretical studies. Systematic experimental tests are lacking, and the operating feasibility of composition adjustment remains unrevealed. In this study, the off-design performance of composition-adjustable CCP is investigated. The performance comparison between composition-adjustable CCP and composition-fixed CCP is developed, and the dynamic characteristics of composition-adjustable CCP in off-design conditions are obtained. Experimental results show that composition adjustment can enhance the off-design performance of CCP, and the maximum relative increase can reach 13.7%. During the off-design conditions, the elapsed time of composition balance is significantly smaller than thermal balance, and the consuming time of composition adjustment can be ignored as long as the liquid level in separator is maintained steady. To accelerate the balancing speed of system, a fast regulation strategy based on flow reverse adjustment is proposed, and the elapsed time can be shortened by around half on the premise of maintaining the stabilization of system performance.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140352"},"PeriodicalIF":9.4,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187591","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 : 2026-02-05DOI: 10.1016/j.energy.2026.140333
Zhi Zhang , Chao Jin , Guofeng Yang , Haifeng Liu , Weide Chang , Zanqiao Shu , Zhiqin Jia , Hui Wang , Tiejian Lin , Hua Zhao , Mingfa Yao
Methanol, a promising carbon-neutral fuel, enables engines operating stoichiometrically with a three-way catalytic converter (TWCC) to achieve high power output while maintaining low emissions. However, engine performance under high-load conditions is limited by knock and maximum in-cylinder pressure (Pmax). Combustion system plays a crucial role, yet research in this field remains scarce. This study performs a numerical investigation of a port-fuel-injection (PFI) heavy-duty spark-ignition (SI) methanol engine, with the objective of guiding combustion system design through enhanced in-cylinder flow, knock mitigation, and thermal efficiency improvement. The results indicate that designing chamber geometry for tumble ratio (TR) enhances turbulent kinetic energy (TKE) more effectively than adjusting swirl or squish flows. The tumble-optimized cylindrical chamber improves indicated thermal efficiency (ITE) by 0.5% over the original chamber. The diameter-depth ratio critically influences flow patterns—larger ratios increase TR during compression but reduce swirl ratio (SR). The high-TR (D86) and high-SR (D70) chambers, featuring large and small diameter-depth ratios respectively, significantly enhance combustion performance, while the medium diameter-depth ratio design (D78) exhibits intermediate performance. Compared to the D78 chamber, the D70 and D86 chambers achieve 0.3% and 0.5% higher ITE, representing improvements of 0.8% and 1.0% over the original chamber, respectively. Furthermore, the diameter-depth ratio significantly affects engine knock characteristics. The knock intensity (KI) initially decreases and then increases with increasing diameter-depth ratio. The D78 chamber exhibits the lowest knock tendency, indicating an optimal diameter-depth ratio near 2.5. This design achieves the highest ITE under both Pmax and knock-limited conditions, reaching 46.92% and 47.21%, respectively.
{"title":"Numerical investigation of combustion system design for knock mitigation and thermal efficiency enhancement in a carbon-neutral methanol engine","authors":"Zhi Zhang , Chao Jin , Guofeng Yang , Haifeng Liu , Weide Chang , Zanqiao Shu , Zhiqin Jia , Hui Wang , Tiejian Lin , Hua Zhao , Mingfa Yao","doi":"10.1016/j.energy.2026.140333","DOIUrl":"10.1016/j.energy.2026.140333","url":null,"abstract":"<div><div>Methanol, a promising carbon-neutral fuel, enables engines operating stoichiometrically with a three-way catalytic converter (TWCC) to achieve high power output while maintaining low emissions. However, engine performance under high-load conditions is limited by knock and maximum in-cylinder pressure (P<sub>max</sub>). Combustion system plays a crucial role, yet research in this field remains scarce. This study performs a numerical investigation of a port-fuel-injection (PFI) heavy-duty spark-ignition (SI) methanol engine, with the objective of guiding combustion system design through enhanced in-cylinder flow, knock mitigation, and thermal efficiency improvement. The results indicate that designing chamber geometry for tumble ratio (TR) enhances turbulent kinetic energy (TKE) more effectively than adjusting swirl or squish flows. The tumble-optimized cylindrical chamber improves indicated thermal efficiency (ITE) by 0.5% over the original chamber. The diameter-depth ratio critically influences flow patterns—larger ratios increase TR during compression but reduce swirl ratio (SR). The high-TR (D86) and high-SR (D70) chambers, featuring large and small diameter-depth ratios respectively, significantly enhance combustion performance, while the medium diameter-depth ratio design (D78) exhibits intermediate performance. Compared to the D78 chamber, the D70 and D86 chambers achieve 0.3% and 0.5% higher ITE, representing improvements of 0.8% and 1.0% over the original chamber, respectively. Furthermore, the diameter-depth ratio significantly affects engine knock characteristics. The knock intensity (KI) initially decreases and then increases with increasing diameter-depth ratio. The D78 chamber exhibits the lowest knock tendency, indicating an optimal diameter-depth ratio near 2.5. This design achieves the highest ITE under both P<sub>max</sub> and knock-limited conditions, reaching 46.92% and 47.21%, respectively.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140333"},"PeriodicalIF":9.4,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187350","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 : 2026-02-05DOI: 10.1016/j.energy.2026.140322
Ching-Wen Lo , Po-Yao Syu , Chen-Kuang Wang , Ya-Yu Chiang
This study investigates the influence of helix structure arrays on saturated pool boiling performance through a systematic parametric evaluation of helix height and density. A total of seven copper-based surfaces, including one flat baseline and six helix-structured configurations, were tested in distilled water under atmospheric pressure. The results demonstrate that appropriately designed helix structures can simultaneously enhance the critical heat flux (CHF) and the heat transfer coefficient (HTC) by up to 78% and 164%, respectively. These enhancements are attributed to the combined effects of shortened bubble residence time, increased bubble departure height, and intensified local convective flow fields. High-speed imaging revealed that taller helix arrays facilitate vapor column detachment and reduce vapor accumulation above the heated surface, while particle image velocimetry (PIV) confirmed the presence of accelerated upward fluid motion induced by vapor ejection and capillary-driven liquid return. These findings underscore the critical role of helix geometry in manipulating interfacial bubble dynamics and promoting liquid–vapor separation, offering promising insights for the thermal design of advanced boiling surfaces.
{"title":"Manipulating bubble departure by varying helix structure heights to enhance pool boiling heat transfer","authors":"Ching-Wen Lo , Po-Yao Syu , Chen-Kuang Wang , Ya-Yu Chiang","doi":"10.1016/j.energy.2026.140322","DOIUrl":"10.1016/j.energy.2026.140322","url":null,"abstract":"<div><div>This study investigates the influence of helix structure arrays on saturated pool boiling performance through a systematic parametric evaluation of helix height and density. A total of seven copper-based surfaces, including one flat baseline and six helix-structured configurations, were tested in distilled water under atmospheric pressure. The results demonstrate that appropriately designed helix structures can simultaneously enhance the critical heat flux (CHF) and the heat transfer coefficient (HTC) by up to 78% and 164%, respectively. These enhancements are attributed to the combined effects of shortened bubble residence time, increased bubble departure height, and intensified local convective flow fields. High-speed imaging revealed that taller helix arrays facilitate vapor column detachment and reduce vapor accumulation above the heated surface, while particle image velocimetry (PIV) confirmed the presence of accelerated upward fluid motion induced by vapor ejection and capillary-driven liquid return. These findings underscore the critical role of helix geometry in manipulating interfacial bubble dynamics and promoting liquid–vapor separation, offering promising insights for the thermal design of advanced boiling surfaces.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140322"},"PeriodicalIF":9.4,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187717","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 : 2026-02-05DOI: 10.1016/j.energy.2026.140328
Xiao-Dong Wang , Xuan Wang , Shao-Dang Hu, Wen-Quan Wang, Yan Yan
The evolving demands of modern power systems impose stricter requirements on the load-following capabilities of hydropower units. Pelton turbines, in response to load adjustments, typically switch the operating nozzles to maintain high hydraulic efficiency. However, the hydrodynamic characteristics during this transitional process remain poorly understood. To address this gap, this study employs a coupled one-dimensional method of characteristics (MOC) and three-dimensional computational fluid dynamics (CFD) method to investigate the transient process during switching of the operating nozzles of Pelton turbine. Specifically, this study investigates the influence of nozzle opening control schemes on flow field, pressure distribution, and external characteristics. The results reveal that, at small nozzle openings, pressure fluctuations in the water supply system become more intense, with a maximum peak-to-peak Cp of 0.065. These fluctuations further induce fluctuations in the torque and radial force of runner, their maximum values are 3.8 and 2.7 times those under steady operating conditions, respectively. Moreover, the dominant frequency of pressure fluctuations on the bucket is 6fn under six-nozzle and four-nozzle operating, whereas with four nozzles, the characteristic frequencies is also including 2fn, and 4fn. Notably, when nozzles are actuated simultaneously in on/off operations, the resulting pressure fluctuations are significantly mitigated, and both the flow rate and torque exhibit a more linear response, which is a recommended nozzle switching mode.
{"title":"Study on the hydrodynamic characteristics of a six-nozzle ultra-large capacity Pelton turbine during the switching of the operating nozzles","authors":"Xiao-Dong Wang , Xuan Wang , Shao-Dang Hu, Wen-Quan Wang, Yan Yan","doi":"10.1016/j.energy.2026.140328","DOIUrl":"10.1016/j.energy.2026.140328","url":null,"abstract":"<div><div>The evolving demands of modern power systems impose stricter requirements on the load-following capabilities of hydropower units. Pelton turbines, in response to load adjustments, typically switch the operating nozzles to maintain high hydraulic efficiency. However, the hydrodynamic characteristics during this transitional process remain poorly understood. To address this gap, this study employs a coupled one-dimensional method of characteristics (MOC) and three-dimensional computational fluid dynamics (CFD) method to investigate the transient process during switching of the operating nozzles of Pelton turbine. Specifically, this study investigates the influence of nozzle opening control schemes on flow field, pressure distribution, and external characteristics. The results reveal that, at small nozzle openings, pressure fluctuations in the water supply system become more intense, with a maximum peak-to-peak <em>C</em><sub><em>p</em></sub> of 0.065. These fluctuations further induce fluctuations in the torque and radial force of runner, their maximum values are 3.8 and 2.7 times those under steady operating conditions, respectively. Moreover, the dominant frequency of pressure fluctuations on the bucket is 6<em>f</em><sub>n</sub> under six-nozzle and four-nozzle operating, whereas with four nozzles, the characteristic frequencies is also including 2<em>f</em><sub>n</sub>, and 4<em>f</em><sub>n</sub>. Notably, when nozzles are actuated simultaneously in on/off operations, the resulting pressure fluctuations are significantly mitigated, and both the flow rate and torque exhibit a more linear response, which is a recommended nozzle switching mode.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140328"},"PeriodicalIF":9.4,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187518","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 : 2026-02-05DOI: 10.1016/j.energy.2026.140263
Qingdong Xuan , Ziyi Chen , Bin Jiang , Bin Zhao , Guiqiang Li , Gang Pei
With the rapid growth of the construction industry, energy consumption and environmental pollution have become critical challenges. Reducing building energy use and advancing renewable energy adoption are key solutions to these problems. To address this issue, a novel asymmetric lens-walled concentrating photovoltaic/daylighting control (LACPC-PV/D) system is proposed in this study, designed for south-facing building walls. The LACPC-PV/D system is mainly derived from the truncation of its core component, i.e., the asymmetric lens-walled compound parabolic concentrator (LACPC) with a truncation length of 20.2 mm, achieving a final geometric concentration ratio of 2.22 × . This system optimizes daylighting performance while maintaining high optical efficiency and electrical output. Ray-tracing simulations and indoor experiments were conducted to investigate the optical, electrical, and daylighting performance of the LACPC-PV/D system. Prototypes of the LACPC-PV/D module (with daylighting) and a reference LACPC-PV module (without daylighting) were fabricated and tested under standard conditions using a solar simulator. Results showed that the LACPC-PV/D module enhanced the short-circuit current, open-circuit voltage, and maximum power by 1.59 × , 4.7%, and 1.78 × , respectively, while the reference LACPC-PV module achieved improvements of 1.66 × , 3.8%, and 1.82 × , respectively. These findings indicate minimal impact on optical concentration performance while achieving a daylighting efficiency of 10% within incidence angles of 0–60°. Additionally, the daylighting performance of the LACPC-PV/D system was compared with conventional semi-transparent PV windows. Ray-tracing simulations demonstrated that, within incidence angles of 15°–85°, the LACPC-PV/D system delivered superior daylighting uniformity, reducing the average coefficient of variation (CV) for illuminance distribution from 4.06 to 2.02. To further evaluate economic performance, the Levelized Cost of Electricity (LCOE) and Simple Payback Period (SPB) were compared between the conventional flat PV system and the LACPC-PV/D system. The LACPC-PV/D system achieves an LCOE of 0.04342 USD/kWh and an SPB of 5.3511 years, compared to 0.04376 USD/kWh and 5.3928 years for the conventional system. Furthermore, its module cost per watt-peak (Wp) is approximately 9.33% lower, demonstrating a comprehensive economic benefit.
{"title":"Experimental and simulation analysis of the optical, electrical, and daylighting performance of the asymmetric concentrating photovoltaic/daylighting system","authors":"Qingdong Xuan , Ziyi Chen , Bin Jiang , Bin Zhao , Guiqiang Li , Gang Pei","doi":"10.1016/j.energy.2026.140263","DOIUrl":"10.1016/j.energy.2026.140263","url":null,"abstract":"<div><div>With the rapid growth of the construction industry, energy consumption and environmental pollution have become critical challenges. Reducing building energy use and advancing renewable energy adoption are key solutions to these problems. To address this issue, a novel asymmetric lens-walled concentrating photovoltaic/daylighting control (LACPC-PV/D) system is proposed in this study, designed for south-facing building walls. The LACPC-PV/D system is mainly derived from the truncation of its core component, i.e., the asymmetric lens-walled compound parabolic concentrator (LACPC) with a truncation length of 20.2 mm, achieving a final geometric concentration ratio of 2.22 × . This system optimizes daylighting performance while maintaining high optical efficiency and electrical output. Ray-tracing simulations and indoor experiments were conducted to investigate the optical, electrical, and daylighting performance of the LACPC-PV/D system. Prototypes of the LACPC-PV/D module (with daylighting) and a reference LACPC-PV module (without daylighting) were fabricated and tested under standard conditions using a solar simulator. Results showed that the LACPC-PV/D module enhanced the short-circuit current, open-circuit voltage, and maximum power by 1.59 × , 4.7%, and 1.78 × , respectively, while the reference LACPC-PV module achieved improvements of 1.66 × , 3.8%, and 1.82 × , respectively. These findings indicate minimal impact on optical concentration performance while achieving a daylighting efficiency of 10% within incidence angles of 0–60°. Additionally, the daylighting performance of the LACPC-PV/D system was compared with conventional semi-transparent PV windows. Ray-tracing simulations demonstrated that, within incidence angles of 15°–85°, the LACPC-PV/D system delivered superior daylighting uniformity, reducing the average coefficient of variation (<em>CV</em>) for illuminance distribution from 4.06 to 2.02. To further evaluate economic performance, the Levelized Cost of Electricity (LCOE) and Simple Payback Period (SPB) were compared between the conventional flat PV system and the LACPC-PV/D system. The LACPC-PV/D system achieves an LCOE of 0.04342 USD/kWh and an SPB of 5.3511 years, compared to 0.04376 USD/kWh and 5.3928 years for the conventional system. Furthermore, its module cost per watt-peak (Wp) is approximately 9.33% lower, demonstrating a comprehensive economic benefit.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140263"},"PeriodicalIF":9.4,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187628","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 : 2026-02-04DOI: 10.1016/j.energy.2026.140216
Zhengyong Li , Youcai Liang , Yan Zhu , Shunchun Yao
High-temperature heat pump technology is promising in the process of electrifying industrial heating. The high temperature characteristics cause limitations of refrigerant, component material, and cycle performance. To this end, this study employs a novel flash tank vapor injection enhanced cycle (NFVI-EEC) to explore the power recovery mechanism of the cycle. It features active dryness regulation, staged expansion, and dual-stage subcooling. In this paper, thermodynamic and economic models of NFVI-EEC are constructed, and the conversion principle and optimization direction of the throttling loss and the heat transfer loss are analyzed in detail. Innovatively, ejector efficiency and vapor injection efficiency, both centered on expansion work recovery capability, are proposed. Under typical operating conditions, using R1224yd(Z)/R1233zd(E) as refrigerant,the vapor injection efficiency of NFVI-EEC is improved by 14.96%-20.73% compared with FVIC; and the ejector efficiency is reduced by 9.99%-18.50% compared with BEEC. R1224yd(Z)/R1233zd(E) achieves the highest COP (3.51) among all refrigerant mixtures evaluated. Therefore, to further enhance the system performance of NFVI-EEC, the ejector efficiency can be used as an optimization target for further improvement. The theoretical framework for expansion process analysis constructed in this study will help guide the optimization of the expansion process in high-temperature heat pumps in the future.
{"title":"Study of power recovery mechanism and system-level thermodynamic optimization of a novel compression high-temperature heat pump","authors":"Zhengyong Li , Youcai Liang , Yan Zhu , Shunchun Yao","doi":"10.1016/j.energy.2026.140216","DOIUrl":"10.1016/j.energy.2026.140216","url":null,"abstract":"<div><div>High-temperature heat pump technology is promising in the process of electrifying industrial heating. The high temperature characteristics cause limitations of refrigerant, component material, and cycle performance. To this end, this study employs a novel flash tank vapor injection enhanced cycle (NFVI-EEC) to explore the power recovery mechanism of the cycle. It features active dryness regulation, staged expansion, and dual-stage subcooling. In this paper, thermodynamic and economic models of NFVI-EEC are constructed, and the conversion principle and optimization direction of the throttling loss and the heat transfer loss are analyzed in detail. Innovatively, ejector efficiency and vapor injection efficiency, both centered on expansion work recovery capability, are proposed. Under typical operating conditions, using R1224yd(Z)/R1233zd(E) as refrigerant,the vapor injection efficiency of NFVI-EEC is improved by 14.96%-20.73% compared with FVIC; and the ejector efficiency is reduced by 9.99%-18.50% compared with BEEC. R1224yd(Z)/R1233zd(E) achieves the highest COP (3.51) among all refrigerant mixtures evaluated. Therefore, to further enhance the system performance of NFVI-EEC, the ejector efficiency can be used as an optimization target for further improvement. The theoretical framework for expansion process analysis constructed in this study will help guide the optimization of the expansion process in high-temperature heat pumps in the future.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140216"},"PeriodicalIF":9.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187247","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 : 2026-02-04DOI: 10.1016/j.energy.2026.140326
Jialiang Dong , Ruikun Wang , Shiteng Tan , Zhenghui Zhao , Qianqian Yin , Jun Cheng , Xuehai Yu , Eric J. Hu , Fuyan Gao
Biochar, with its well-developed pore structure and tunable surface chemistry, has been widely employed for heavy metal adsorption. However, the biochar after adsorption of heavy metals suffers from high risk of secondary pollution and difficulty in resource utilization. This study explores a feasible approach to converting it into an efficient CO2 adsorbent. Heavy metal ions (represented by Ni2+ in this study) are primarily captured via the mesoporous structure of biochar and can be stably anchored to the carbon skeleton after high temperature treatment. This process introduces alkali metal oxide sites on the biochar surface, which were confirmed as chemisorption centers for CO2 by in situ near-ambient pressure X-ray photoelectron spectroscopy (in situ NAP-XPS). Meanwhile, the adsorbed Ni2+ acts as in situ structural template, inducing the evolution of mesopores into narrow micropores, increasing the intermolecular forces between the pore walls and CO2. The synergistic enhancement effect of chemical and physical adsorption significantly improves the CO2 adsorption performance of biochar. The Ni-loaded biochar achieves a CO2 adsorption capacity of 4.49 mmol/g at 25 °C and 1 bar, and a CO2/N2 dynamic separation coefficient of 74.47 in multi-component breakthrough experiments. This study provides a green and sustainable approach that combines heavy metal pollution control with the development of CO2 capture materials, delivering dual energy and environmental benefits.
{"title":"Upgraded utilization of biochar after heavy metal (Ni) adsorption for CO2 capture","authors":"Jialiang Dong , Ruikun Wang , Shiteng Tan , Zhenghui Zhao , Qianqian Yin , Jun Cheng , Xuehai Yu , Eric J. Hu , Fuyan Gao","doi":"10.1016/j.energy.2026.140326","DOIUrl":"10.1016/j.energy.2026.140326","url":null,"abstract":"<div><div>Biochar, with its well-developed pore structure and tunable surface chemistry, has been widely employed for heavy metal adsorption. However, the biochar after adsorption of heavy metals suffers from high risk of secondary pollution and difficulty in resource utilization. This study explores a feasible approach to converting it into an efficient CO<sub>2</sub> adsorbent. Heavy metal ions (represented by Ni<sup>2+</sup> in this study) are primarily captured via the mesoporous structure of biochar and can be stably anchored to the carbon skeleton after high temperature treatment. This process introduces alkali metal oxide sites on the biochar surface, which were confirmed as chemisorption centers for CO<sub>2</sub> by in situ near-ambient pressure X-ray photoelectron spectroscopy (in situ NAP-XPS). Meanwhile, the adsorbed Ni<sup>2+</sup> acts as in situ structural template, inducing the evolution of mesopores into narrow micropores, increasing the intermolecular forces between the pore walls and CO<sub>2</sub>. The synergistic enhancement effect of chemical and physical adsorption significantly improves the CO<sub>2</sub> adsorption performance of biochar. The Ni-loaded biochar achieves a CO<sub>2</sub> adsorption capacity of 4.49 mmol/g at 25 °C and 1 bar, and a CO<sub>2</sub>/N<sub>2</sub> dynamic separation coefficient of 74.47 in multi-component breakthrough experiments. This study provides a green and sustainable approach that combines heavy metal pollution control with the development of CO<sub>2</sub> capture materials, delivering dual energy and environmental benefits.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140326"},"PeriodicalIF":9.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187631","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 : 2026-02-04DOI: 10.1016/j.energy.2026.140327
Zhen Huang , Peng Dai , Jisheng Zhang
Xiushan Island is situated in Zhoushan waters, which harbors abundant tidal current energy resources in China, with complex sub-channels surrounding it. This study employs a high-resolution numerical model of tidal currents in Zhoushan waters to evaluate the tidal energy potential and explore the feasibility of integrated exploration of multi-channels around Xiushan Island. Furthermore, the study investigates the competitive effects of sub-channels and assesses the resulting redistribution of flow rate and velocity. Results show that the theoretical tidal current energy potential in the vicinity of Xiushan Island is approximately 1050 MW. Joint exploration of multiple channels yields an energy increase of 10.11% to 33.92% compared to the independent development of each channel. This phenomenon is induced by the competitive effects of flow dynamics when turbines are installed in the multi - channel zone. Numerical results demonstrate that the flow rate of the parallel channels can be increased by up to 17% during the development of individual channels. This integrated approach enables a more effective and comprehensive extraction of tidal current energy resources within the study area.
{"title":"Joint development of tidal current energy in multi-channels surrounding Xiushan Island, China","authors":"Zhen Huang , Peng Dai , Jisheng Zhang","doi":"10.1016/j.energy.2026.140327","DOIUrl":"10.1016/j.energy.2026.140327","url":null,"abstract":"<div><div>Xiushan Island is situated in Zhoushan waters, which harbors abundant tidal current energy resources in China, with complex sub-channels surrounding it. This study employs a high-resolution numerical model of tidal currents in Zhoushan waters to evaluate the tidal energy potential and explore the feasibility of integrated exploration of multi-channels around Xiushan Island. Furthermore, the study investigates the competitive effects of sub-channels and assesses the resulting redistribution of flow rate and velocity. Results show that the theoretical tidal current energy potential in the vicinity of Xiushan Island is approximately 1050 MW. Joint exploration of multiple channels yields an energy increase of 10.11% to 33.92% compared to the independent development of each channel. This phenomenon is induced by the competitive effects of flow dynamics when turbines are installed in the multi - channel zone. Numerical results demonstrate that the flow rate of the parallel channels can be increased by up to 17% during the development of individual channels. This integrated approach enables a more effective and comprehensive extraction of tidal current energy resources within the study area.</div></div>","PeriodicalId":11647,"journal":{"name":"Energy","volume":"347 ","pages":"Article 140327"},"PeriodicalIF":9.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187624","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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