Pub Date : 2026-01-24DOI: 10.1016/j.enconman.2026.121125
Ze Bai , Yaohua Zhao , Zhenhua Quan , Yiyang Liu , Wanli Chang
Conventional flat-plate photovoltaic/thermal (PVT) modules suffer from low solar energy utilization efficiency and unstable heat supply when used as heat pump evaporators. Additionally, their heat dissipation capabilities are limited when used as condensers. To address these limitations, this study proposes a novel micro heat pipe array-integrated PVT–air evaporator/condenser (MHPA-PVTAE/C), coupled with a dual-source direct expansion heat pump. Seasonal experiments were conducted to characterize its trigeneration performance, and an adaptive heating-mode switching strategy was developed using the coefficient of performance for heating (COP(H)) as the optimization objective based on solar irradiance and ambient temperature. The system achieved a COP(H) of 6.2 (summer) and 4.9 (winter), power generation efficiency of up to 14%, and a COP(C) of 2.7. Throughout continuous multi-day tests, the compressor exhaust temperature remained below 90 °C, and the suction/exhaust pressure variation rates were both below 5%, demonstrating reliable and stable operation when the MHPA-PVTAE/C functioned as the evaporator or condenser. Compared with existing systems, the novel system enhanced the COP(H) by 13.1–68.1% (summer) and 15.3–75.2% (winter), and increased the COP(C) by 5.2–42.4%, providing a validated technical route for building-scale trigeneration system.
{"title":"Research on the performance and mode switching strategy of the photovoltaic/thermal-air dual heat source direct expansion heat pump system based on micro heat pipe arrays","authors":"Ze Bai , Yaohua Zhao , Zhenhua Quan , Yiyang Liu , Wanli Chang","doi":"10.1016/j.enconman.2026.121125","DOIUrl":"10.1016/j.enconman.2026.121125","url":null,"abstract":"<div><div>Conventional flat-plate photovoltaic/thermal (PVT) modules suffer from low solar energy utilization efficiency and unstable heat supply when used as heat pump evaporators. Additionally, their heat dissipation capabilities are limited when used as condensers. To address these limitations, this study proposes a novel micro heat pipe array-integrated PVT–air evaporator/condenser (MHPA-PVTAE/C), coupled with a dual-source direct expansion heat pump. Seasonal experiments were conducted to characterize its trigeneration performance, and an adaptive heating-mode switching strategy was developed using the coefficient of performance for heating (<em>COP(H)</em>) as the optimization objective based on solar irradiance and ambient temperature. The system achieved a <em>COP(H)</em> of 6.2 (summer) and 4.9 (winter), power generation efficiency of up to 14%, and a <em>COP(C)</em> of 2.7. Throughout continuous multi-day tests, the compressor exhaust temperature remained below 90 °C, and the suction/exhaust pressure variation rates were both below 5%, demonstrating reliable and stable operation when the MHPA-PVTAE/C functioned as the evaporator or condenser. Compared with existing systems, the novel system enhanced the <em>COP(H)</em> by 13.1–68.1% (summer) and 15.3–75.2% (winter), and increased the <em>COP(C)</em> by 5.2–42.4%, providing a validated technical route for building-scale trigeneration system.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121125"},"PeriodicalIF":10.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036398","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}
Fault detection in grid-connected photovoltaic (GCPV) systems is critical for ensuring operational safety and efficiency, yet the availability of labeled fault data in real-world deployments is limited. Reliable anomaly detection in GCPV systems is vital for ensuring operational safety, minimizing energy losses, and maintaining efficiency. This study presents a systematic, mode-aware benchmarking of semi-supervised anomaly detection methods for GCPV monitoring under realistic operating conditions. This study evaluates four semi-supervised techniques, Isolation Forest (iForest), Local Outlier Factor (LOF), One-Class SVM (1SVM), and Elliptic Envelope (EE), for fault detection in GCPV systems operating under Intermediate and Maximum Power Point Tracking (IPPT/MPPT) modes. Using the GPVS-Faults dataset, which contains simulated fault scenarios generated from a grid-connected PV system emulator, all models are trained exclusively on fault-free data, following a strictly semi-supervised paradigm, and evaluated across multiple metrics, including accuracy, F1-score, AUC, and false positive rate (FPR). Experimental results show that EE achieves the best average accuracy and AUC with the lowest FPR across both operating modes, reaching an average accuracy of 94.68% under MPPT and 93.54% under IPPT. LOF exhibits the highest sensitivity and F1-score, but at the expense of increased false positives, while iForest provides a balanced trade-off between precision and recall. Beyond detection performance, this work emphasizes reproducibility and interpretability in semi-supervised PV fault detection. To enhance transparency, SHapley Additive exPlanations (SHAP) analysis is used as a post-hoc interpretability layer based on an auxiliary XGBoost model, revealing fault-specific feature contributions aligned with physical system behavior. Overall, the results demonstrate complementary strengths among the evaluated methods and highlight the effectiveness of EE for low-false-alarm fault detection, alongside the value of lightweight, explainable, and mode-aware semi-supervised frameworks in supporting GCPV monitoring.
{"title":"Semi-supervised anomaly detection in photovoltaic systems under power tracking mode","authors":"Fouzi Harrou , Abdelkader Dairi , Abdelhakim Dorbane , Bilal Taghezouit , Ying Sun","doi":"10.1016/j.enconman.2026.121114","DOIUrl":"10.1016/j.enconman.2026.121114","url":null,"abstract":"<div><div>Fault detection in grid-connected photovoltaic (GCPV) systems is critical for ensuring operational safety and efficiency, yet the availability of labeled fault data in real-world deployments is limited. Reliable anomaly detection in GCPV systems is vital for ensuring operational safety, minimizing energy losses, and maintaining efficiency. This study presents a systematic, mode-aware benchmarking of semi-supervised anomaly detection methods for GCPV monitoring under realistic operating conditions. This study evaluates four semi-supervised techniques, Isolation Forest (iForest), Local Outlier Factor (LOF), One-Class SVM (1SVM), and Elliptic Envelope (EE), for fault detection in GCPV systems operating under Intermediate and Maximum Power Point Tracking (IPPT/MPPT) modes. Using the GPVS-Faults dataset, which contains simulated fault scenarios generated from a grid-connected PV system emulator, all models are trained exclusively on fault-free data, following a strictly semi-supervised paradigm, and evaluated across multiple metrics, including accuracy, F1-score, AUC, and false positive rate (FPR). Experimental results show that EE achieves the best average accuracy and AUC with the lowest FPR across both operating modes, reaching an average accuracy of 94.68% under MPPT and 93.54% under IPPT. LOF exhibits the highest sensitivity and F1-score, but at the expense of increased false positives, while iForest provides a balanced trade-off between precision and recall. Beyond detection performance, this work emphasizes reproducibility and interpretability in semi-supervised PV fault detection. To enhance transparency, SHapley Additive exPlanations (SHAP) analysis is used as a post-hoc interpretability layer based on an auxiliary XGBoost model, revealing fault-specific feature contributions aligned with physical system behavior. Overall, the results demonstrate complementary strengths among the evaluated methods and highlight the effectiveness of EE for low-false-alarm fault detection, alongside the value of lightweight, explainable, and mode-aware semi-supervised frameworks in supporting GCPV monitoring.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121114"},"PeriodicalIF":10.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036462","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 : 2026-01-23DOI: 10.1016/j.enconman.2026.121064
Farah Souayfane , Ricardo M. Lima , Asaad Katoua , Omar Knio
Integrating large-scale renewable energy and storage systems is essential for sustainability in hot desert regions. However, resource variability and extreme weather pose operational and economic challenges, emphasizing the need for resilient systems. This study develops a TRNSYS simulation-based multi-objective optimization framework to design a resilient renewable energy system for a community in Saudi Arabia. Its novelty lies in the iterative incorporation of extreme weather derived from 25 years of historical weather data and the leveraging of sector coupling through the operational flexibility of a desalination plant. The optimization identifies optimal capacities for a system combining concentrated solar power, photovoltaic, and wind turbines, coupled with battery and thermal storage. The most economical off-grid configuration yields a life cycle cost of $1.46 billion and a levelized cost of energy of 0.1687 $/kWh with concentrated solar power supplying 96% of the energy (peak load of 86 MW and annual energy consumption of 505 GWh), which avoids 330,900 tonnes of emissions per year. This off-grid system, designed to withstand past extreme low solar radiation and high temperature days, requires additional generation and storage capacity, which increases the cost by 19%. Leveraging the desalination plant’s operational flexibility reduces the system’s cost by 2.7% while further enhancing system resilience. The framework provides a practical and adaptable method for designing resilient renewable energy systems in response to variable extreme weather conditions, highlighting the cost of resilience and demonstrating that power coupling with desalination can help mitigate the cost of achieving resilience.
{"title":"Integrating weather extremes and desalination flexibility to design a resilient concentrated solar power–photovoltaic–wind system with battery and thermal storage using TRNSYS","authors":"Farah Souayfane , Ricardo M. Lima , Asaad Katoua , Omar Knio","doi":"10.1016/j.enconman.2026.121064","DOIUrl":"10.1016/j.enconman.2026.121064","url":null,"abstract":"<div><div>Integrating large-scale renewable energy and storage systems is essential for sustainability in hot desert regions. However, resource variability and extreme weather pose operational and economic challenges, emphasizing the need for resilient systems. This study develops a TRNSYS simulation-based multi-objective optimization framework to design a resilient renewable energy system for a community in Saudi Arabia. Its novelty lies in the iterative incorporation of extreme weather derived from 25 years of historical weather data and the leveraging of sector coupling through the operational flexibility of a desalination plant. The optimization identifies optimal capacities for a system combining concentrated solar power, photovoltaic, and wind turbines, coupled with battery and thermal storage. The most economical off-grid configuration yields a life cycle cost of $1.46 billion and a levelized cost of energy of 0.1687 $/kWh with concentrated solar power supplying 96% of the energy (peak load of 86 MW and annual energy consumption of 505 GWh), which avoids 330,900 tonnes of <span><math><msub><mrow><mi>CO</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> emissions per year. This off-grid system, designed to withstand past extreme low solar radiation and high temperature days, requires additional generation and storage capacity, which increases the cost by 19%. Leveraging the desalination plant’s operational flexibility reduces the system’s cost by 2.7% while further enhancing system resilience. The framework provides a practical and adaptable method for designing resilient renewable energy systems in response to variable extreme weather conditions, highlighting the cost of resilience and demonstrating that power coupling with desalination can help mitigate the cost of achieving resilience.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"351 ","pages":"Article 121064"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023449","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 : 2026-01-23DOI: 10.1016/j.enconman.2026.121105
Oraib Dawaghreh, Sharaf K. Magableh, Caisheng Wang
Hydropower opportunities in many lake-rich regions remain largely unexploited. This is because long horizontal distances and modest elevation differences prohibit the feasibility of traditional pumped storage systems. The need for terrain-adaptive long-duration storage motivates the exploration of multi-stage, cascade-based designs capable of bridging these spatial constraints. This study investigates whether introducing intermediate reservoirs can transform geographically constrained lake systems into practical pumped hydro storage sites. An integrated modeling framework, including hydropower, solar, and wind simulation, geospatial analysis, and multi-objective evolutionary optimization, is applied using real meteorological and electrical load data from Mountain Lake, Michigan to determine optimal reservoir locations, storage capacities, and renewable generation sizing. Three cases were evaluated to assess the impact of different cascade configurations. Among them, the configuration with one intermediate reservoir achieves approximately 99.97 percent reliability with a levelized cost of energy between 0.133 and 0.165 USD per kilowatt-hour, while the two-reservoir arrangement demonstrates even lower cost and higher reliability. These findings demonstrate that a cascade configuration can significantly improve hydraulic performance and economic feasibility in low-slope terrains. The study concludes that multi-stage micro-pumped hydro architectures offer a geographically adaptable pathway for long-duration energy storage and can be deployed in regions where conventional two-reservoir systems are not viable.
{"title":"Cascade-pumped micro-hydro storage systems: A new design framework for efficient energy generation and storage in challenging topographies","authors":"Oraib Dawaghreh, Sharaf K. Magableh, Caisheng Wang","doi":"10.1016/j.enconman.2026.121105","DOIUrl":"10.1016/j.enconman.2026.121105","url":null,"abstract":"<div><div>Hydropower opportunities in many lake-rich regions remain largely unexploited. This is because long horizontal distances and modest elevation differences prohibit the feasibility of traditional pumped storage systems. The need for terrain-adaptive long-duration storage motivates the exploration of multi-stage, cascade-based designs capable of bridging these spatial constraints. This study investigates whether introducing intermediate reservoirs can transform geographically constrained lake systems into practical pumped hydro storage sites. An integrated modeling framework, including hydropower, solar, and wind simulation, geospatial analysis, and multi-objective evolutionary optimization, is applied using real meteorological and electrical load data from Mountain Lake, Michigan to determine optimal reservoir locations, storage capacities, and renewable generation sizing. Three cases were evaluated to assess the impact of different cascade configurations. Among them, the configuration with one intermediate reservoir achieves approximately 99.97 percent reliability with a levelized cost of energy between 0.133 and 0.165 USD per kilowatt-hour, while the two-reservoir arrangement demonstrates even lower cost and higher reliability. These findings demonstrate that a cascade configuration can significantly improve hydraulic performance and economic feasibility in low-slope terrains. The study concludes that multi-stage micro-pumped hydro architectures offer a geographically adaptable pathway for long-duration energy storage and can be deployed in regions where conventional two-reservoir systems are not viable.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121105"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033474","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 : 2026-01-23DOI: 10.1016/j.enconman.2026.121101
Mei Wang , Guoming Wen , Lang Liu , Shuangming Wang
As a strategic alternative to conventional oil and gas resources, tar-rich coal, coupled with its low-carbon in-situ extraction technologies, is rapidly emerging as a pivotal focus for sustainable energy development. This study presents an innovative tower type solar in-situ pyrolysis system for tar-rich coal (TS-IPS/TRC) to significantly reduce energy consumption in tar-rich coal extraction. A transient multiphysics model, integrating solar thermal conversion, nitrogen mediated heat transfer, and pyrolysis reaction kinetics, was constructed to investigate the influence of two critical operating parameters, nitrogen temperature and flow rate, on the dynamic behavior of the system. The results demonstrate that the heating rate during the initial pyrolysis stage is more responsive to variations in flow rate. Spatially, increasing the flow rate significantly enhance the heating effect near the injection well, while the effect gradually diminish in the regions farther away from the injection well. In accordance with system operational requirements, the optimal pyrolysis temperature was ascertained to be 983.15 K under a 24–hour cyclic operation strategy. In light of the temporal variations in solar energy, three operational approaches were subjected to rigorous evaluation. The results reveal that intermittent operation coupled with an elevated inlet temperature and a reduced flow rate of the heat transfer medium significantly enhances techno–economic performance. The intermittent heating mode effectively improves temperature uniformity within the pyrolysis zone. A 12–hour cyclic operation strategy is recommended. Increasing the inlet temperature from 933.15 K to 1033.15 K and decreasing the inlet flow velocity from 5 m/s to 2 m/s substantially increases the gas production rate by 61 %. The TS-IPS/TRC system can reduce power consumption by 61 % and decrease carbon emissions by 2.52 × 108 kg under the pyrolysis condition of 80 % of tar-rich coal. The proposed system demonstrates great potential in terms of energy conservation and emission reduction by pioneering a novel method for sustainable extraction of tar-rich coal in a low-carbon way.
{"title":"Dynamic modelling and characteristics analysis of a novel in situ tar-rich coal pyrolysis mining system driven by solar energy","authors":"Mei Wang , Guoming Wen , Lang Liu , Shuangming Wang","doi":"10.1016/j.enconman.2026.121101","DOIUrl":"10.1016/j.enconman.2026.121101","url":null,"abstract":"<div><div>As a strategic alternative to conventional oil and gas resources, tar-rich coal, coupled with its low-carbon in-situ extraction technologies, is rapidly emerging as a pivotal focus for sustainable energy development. This study presents an innovative tower type solar in-situ pyrolysis system for tar-rich coal (TS-IPS/TRC) to significantly reduce energy consumption in tar-rich coal extraction. A transient multiphysics model, integrating solar thermal conversion, nitrogen mediated heat transfer, and pyrolysis reaction kinetics, was constructed to investigate the influence of two critical operating parameters, nitrogen temperature and flow rate, on the dynamic behavior of the system. The results demonstrate that the heating rate during the initial pyrolysis stage is more responsive to variations in flow rate. Spatially, increasing the flow rate significantly enhance the heating effect near the injection well, while the effect gradually diminish in the regions farther away from the injection well. In accordance with system operational requirements, the optimal pyrolysis temperature was ascertained to be 983.15 K under a 24–hour cyclic operation strategy. In light of the temporal variations in solar energy, three operational approaches were subjected to rigorous evaluation. The results reveal that intermittent operation coupled with an elevated inlet temperature and a reduced flow rate of the heat transfer medium significantly enhances techno–economic performance. The intermittent heating mode effectively improves temperature uniformity within the pyrolysis zone. A 12–hour cyclic operation strategy is recommended. Increasing the inlet temperature from 933.15 K to 1033.15 K and decreasing the inlet flow velocity from 5 m/s to 2 m/s substantially increases the gas production rate by 61 %. The TS-IPS/TRC system can reduce power consumption by 61 % and decrease carbon emissions by 2.52 × 10<sup>8</sup> kg under the pyrolysis condition of 80 % of tar-rich coal. The proposed system demonstrates great potential in terms of energy conservation and emission reduction by pioneering a novel method for sustainable extraction of tar-rich coal in a low-carbon way.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121101"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033472","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 : 2026-01-23DOI: 10.1016/j.enconman.2026.121055
Talie Tohidi Moghadam , Brian Norton , Ken Bruton , Dominic T.J. O’Sullivan
Reducing heating-related energy demand in buildings is a critical step toward decarbonisation. This study investigates the feasibility of using unglazed transpired solar collectors to pre-heat ventilation air. It is hypothesised that such systems can significantly lower energy use and carbon emissions while offering economic benefits. An experimental unglazed transpired solar collectors system was installed in a university building in Cork, Ireland, and its performance was evaluated through real-time measurements and validated against simulations using the “RETScreen Expert” tool. The validated model was then scaled to a full-facade application (163 m2), estimating a 24% reduction in annual heating energy use and a 23.4% decrease in greenhouse gas emissions. The system demonstrated a simple payback period of 10.3 years and an internal rate of return of 12.2% on equity. However, the financial outcomes remain closely linked to future heating fuel price trends, and the exclusion of auxiliary equipment costs (e.g., ducts, fans, filters) reflects a focus on core system performance based on reliably available data. These findings highlight the potential of unglazed transpired solar collectors for energy savings and emissions reduction, while also identifying areas for further research and detailed cost modelling.
{"title":"Performance and viability of transpired solar collectors for pre-heating ventilation air","authors":"Talie Tohidi Moghadam , Brian Norton , Ken Bruton , Dominic T.J. O’Sullivan","doi":"10.1016/j.enconman.2026.121055","DOIUrl":"10.1016/j.enconman.2026.121055","url":null,"abstract":"<div><div>Reducing heating-related energy demand in buildings is a critical step toward decarbonisation. This study investigates the feasibility of using unglazed transpired solar collectors to pre-heat ventilation air. It is hypothesised that such systems can significantly lower energy use and carbon emissions while offering economic benefits. An experimental unglazed transpired solar collectors system was installed in a university building in Cork, Ireland, and its performance was evaluated through real-time measurements and validated against simulations using the “RETScreen Expert” tool. The validated model was then scaled to a full-facade application (163 m<sup>2</sup>), estimating a 24% reduction in annual heating energy use and a 23.4% decrease in greenhouse gas emissions. The system demonstrated a simple payback period of 10.3 years and an internal rate of return of 12.2% on equity. However, the financial outcomes remain closely linked to future heating fuel price trends, and the exclusion of auxiliary equipment costs (e.g., ducts, fans, filters) reflects a focus on core system performance based on reliably available data. These findings highlight the potential of unglazed transpired solar collectors for energy savings and emissions reduction, while also identifying areas for further research and detailed cost modelling.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121055"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033475","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}
As one of the cutting-edge power technologies, the supercritical carbon dioxide (sCO2) Brayton cycle (SCBC) power generation system features broad heat source compatibility. Beyond traditional fossil fuels, it can be coupled with fourth-generation nuclear reactors or concentrating solar thermal systems, demonstrating significant development potential. This study investigates the dynamic behavior of a recompression sCO2 Brayton cycle (RCBC) power system through variations in the mass flow rates of fluids in the heater hot side (HHS) and the pre-cooler cold side (PCS). The results show that when the HHS flow rate changes, the system takes about 300 s to stabilize; while the system stabilizes faster when the PCS flow rate changes, reaching stability in about 200 s. However, the excessive flow rate in the HHS induces severe temperature transients that may lead to thermo-mechanical fatigue in the heater. A reduction in the flow rate in the HHS nonlinearly degrades the turbine performance. When the flow rate drops by 25%, the turbine efficiency only decreases by 0.3%. When the flow rate drops by 75%, the turbine efficiency decreases by 5.5%. The influence of the change in the HHS flow rate on the efficiency of the compressor can be ignored. However, the main compressor is highly sensitive to changes in the flow rate in the PCS. When the flow rate drops by 50%, the efficiency of the main compressor decreases by approximately 0.5%. For every 25% increase in the flow rate, the efficiency of the main compressor rises by nearly 0.3%. Adjusting the flow rate in the PCS can rapidly change total compressor power consumption, and adjusting the flow rate in the HHS can rapidly change the net power of the turbine. This study provides a reference for designing reasonable control strategies when disturbances occur in the HHS or PCS for RCBC systems, aiming to reduce system response time and mitigate detrimental fluctuations.
{"title":"Transient characteristics of recompression supercritical CO2 power system under variable heating and cooling conditions","authors":"Wenxi Jiang, Xin Wang, Yuanyang Zhao, Yunxia Liu, Guangbin Liu, Qichao Yang, Liansheng Li","doi":"10.1016/j.enconman.2026.121117","DOIUrl":"10.1016/j.enconman.2026.121117","url":null,"abstract":"<div><div>As one of the cutting-edge power technologies, the supercritical carbon dioxide (sCO<sub>2</sub>) Brayton cycle (SCBC) power generation system features broad heat source compatibility. Beyond traditional fossil fuels, it can be coupled with fourth-generation nuclear reactors or concentrating solar thermal systems, demonstrating significant development potential. This study investigates the dynamic behavior of a recompression sCO<sub>2</sub> Brayton cycle (RCBC) power system through variations in the mass flow rates of fluids in the heater hot side (HHS) and the pre-cooler cold side (PCS). The results show that when the HHS flow rate changes, the system takes about 300 s to stabilize; while the system stabilizes faster when the PCS flow rate changes, reaching stability in about 200 s. However, the excessive flow rate in the HHS induces severe temperature transients that may lead to thermo-mechanical fatigue in the heater. A reduction in the flow rate in the HHS nonlinearly degrades the turbine performance. When the flow rate drops by 25%, the turbine efficiency only decreases by 0.3%. When the flow rate drops by 75%, the turbine efficiency decreases by 5.5%. The influence of the change in the HHS flow rate on the efficiency of the compressor can be ignored. However, the main compressor is highly sensitive to changes in the flow rate in the PCS. When the flow rate drops by 50%, the efficiency of the main compressor decreases by approximately 0.5%. For every 25% increase in the flow rate, the efficiency of the main compressor rises by nearly 0.3%. Adjusting the flow rate in the PCS can rapidly change total compressor power consumption, and adjusting the flow rate in the HHS can rapidly change the net power of the turbine. This study provides a reference for designing reasonable control strategies when disturbances occur in the HHS or PCS for RCBC systems, aiming to reduce system response time and mitigate detrimental fluctuations.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121117"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033471","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 : 2026-01-23DOI: 10.1016/j.enconman.2026.121090
Mariem Hentati, Ahlem Boussetta, Amal Elleuch, Kamel Halouani
This study presents an advanced thermodynamic assessment of a hybrid SOFC-Gas Turbine system designed to valorize flared gas. Building on previous numerical modeling in ASPEN PLUS V14 and MATLAB softwares, the analysis is extended through exergy-based 3E methodologies namely exergy, exergoeconomic, and exergoenvironmental analyses, with environmental impacts allocated to exergy streams using LCA. The system achieves a first-law efficiency of 63.04%, an exergetic efficiency of 37.5%, and total exergy destruction cost and environmental impact rates of 7655.73 $/h and 777.02 Pts/h, respectively. Results show that the GT-subsystem contributes most to the exergy destruction, cost formation, and environmental burden, while the IR-SOFC-subsystem exhibits superior thermodynamic and economic performance. The SOFC generates electricity at a markedly lower unit cost (0.072 $/MJ) and with a lower specific environmental impact (37.64 mPts/MJ) than the GT equipment (0.42 $/MJ and 51.12 mPts/MJ). The carbon footprint assessment of the proposed hybrid system demonstrates its strong competitiveness, with CO2 emission levels (0.125 t/GJ). Despite being fueled by flared gas, the system exhibits a markedly lower environmental burden compared to conventional fossil-based systems reported in literature, positioning itself closer to sustainable pathways while remaining far from the high-emission profiles of petroleum and coal.
本研究提出了一种先进的sofc -燃气轮机混合系统的热力学评估，该系统设计用于燃烧气体。在先前使用ASPEN PLUS V14和MATLAB软件进行数值模拟的基础上，该分析通过基于火用的3E方法进行扩展，即火用、火用经济和火用环境分析，并使用LCA将环境影响分配给火用流。该系统的第一定律效率为63.04%，火用效率为37.5%，总火用破坏成本和环境影响率分别为7655.73美元/小时和777.02 Pts/小时。结果表明，gt分系统对火用破坏、成本形成和环境负担的贡献最大，而ir - sofc分系统表现出更好的热力学和经济性能。SOFC发电的单位成本（0.072美元/兆焦耳）和特定环境影响（37.64 mPts/兆焦耳）明显低于GT设备（0.42美元/兆焦耳和51.12 mPts/兆焦耳）。碳足迹评估表明，混合动力系统具有较强的竞争力，二氧化碳排放水平为0.125 t/GJ。尽管该系统使用燃烧气体作为燃料，但与文献中报道的传统化石燃料系统相比，该系统的环境负担明显较低，使其更接近可持续发展的道路，同时远离石油和煤炭的高排放特征。
{"title":"Exergy, exergoeconomic, and exergoenvironmental assessment of a flared gas-fuel SOFC-gas turbine hybrid system","authors":"Mariem Hentati, Ahlem Boussetta, Amal Elleuch, Kamel Halouani","doi":"10.1016/j.enconman.2026.121090","DOIUrl":"10.1016/j.enconman.2026.121090","url":null,"abstract":"<div><div>This study presents an advanced thermodynamic assessment of a hybrid SOFC-Gas Turbine system designed to valorize flared gas. Building on previous numerical modeling in ASPEN PLUS V14 and MATLAB softwares, the analysis is extended through exergy-based 3E methodologies namely exergy, exergoeconomic, and exergoenvironmental analyses, with environmental impacts allocated to exergy streams using LCA. The system achieves a first-law efficiency of 63.04%, an exergetic efficiency of 37.5%, and total exergy destruction cost and environmental impact rates of 7655.73 $/h and 777.02 Pts/h, respectively. Results show that the GT-subsystem contributes most to the exergy destruction, cost formation, and environmental burden, while the IR-SOFC-subsystem exhibits superior thermodynamic and economic performance. The SOFC generates electricity at a markedly lower unit cost (0.072 $/MJ) and with a lower specific environmental impact (37.64 mPts/MJ) than the GT equipment (0.42 $/MJ and 51.12 mPts/MJ). The carbon footprint assessment of the proposed hybrid system demonstrates its strong competitiveness, with CO<sub>2</sub> emission levels (0.125 t/GJ). Despite being fueled by flared gas, the system exhibits a markedly lower environmental burden compared to conventional fossil-based systems reported in literature, positioning itself closer to sustainable pathways while remaining far from the high-emission profiles of petroleum and coal.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121090"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036397","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 : 2026-01-23DOI: 10.1016/j.enconman.2026.121112
Yanfei Li, Jian Sun, Jamie Lian, Kashif Nawaz
Heat pumps are effective cooling and heating appliances to save energy in buildings. However, traditional heat pump models are challenging to integrate with building demands in a co-simulation environment because of the nonlinear thermodynamics of refrigerants. Developing digital twin representatives for heat pumps capable of faster calculations with good accuracy is desirable. This study aimed to establish a generic deep learning–based digital twin for heat pumps with a large amount of high-fidelity data. Two refrigerants for two different heat pumps were considered: an air source heat pump with refrigerant R-410A, an air source heat pump with refrigerant CO2, a water source heat pump with refrigerant R-410A, and a water source heat pump with refrigerant CO2. Results showed that the deep learning (long short-term memory) models effectively represented these four heat pumps as a digital twin: (a) accuracy for training and testing showed smaller than 0.02 for heating electricity and heating demands, and (b) the digital twins showed good consistency with original data for heating electricity and heating demands (root mean square errors of less than 0.12 W and 0.19 W, respectively). Therefore, deep learning–based heat pump models can be used in the co-simulation of building mechanical systems.
{"title":"Deep learning–based digital twins for heat pumps","authors":"Yanfei Li, Jian Sun, Jamie Lian, Kashif Nawaz","doi":"10.1016/j.enconman.2026.121112","DOIUrl":"10.1016/j.enconman.2026.121112","url":null,"abstract":"<div><div>Heat pumps are effective cooling and heating appliances to save energy in buildings. However, traditional heat pump models are challenging to integrate with building demands in a co-simulation environment because of the nonlinear thermodynamics of refrigerants. Developing digital twin representatives for heat pumps capable of faster calculations with good accuracy is desirable. This study aimed to establish a generic deep learning–based digital twin for heat pumps with a large amount of high-fidelity data. Two refrigerants for two different heat pumps were considered: an air source heat pump with refrigerant R-410A, an air source heat pump with refrigerant CO<sub>2</sub>, a water source heat pump with refrigerant R-410A, and a water source heat pump with refrigerant CO<sub>2</sub>. Results showed that the deep learning (long short-term memory) models effectively represented these four heat pumps as a digital twin: (a) accuracy for training and testing showed smaller than 0.02 for heating electricity and heating demands, and (b) the digital twins showed good consistency with original data for heating electricity and heating demands (root mean square errors of less than 0.12 W and 0.19 W, respectively). Therefore, deep learning–based heat pump models can be used in the co-simulation of building mechanical systems.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121112"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033470","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 : 2026-01-23DOI: 10.1016/j.enconman.2026.121102
Yihang Jiang , Shuqiang Zhao , Hui Wang , Chutong Wang , Ming Cheng
The rapid transition toward low-carbon energy systems with high shares of renewable energy sources has led to declining power system inertia and heightened risks of frequency and voltage instability. Synchronous condensers have emerged as a proven solution to mitigate these challenges, but existing placement strategies mainly focus on short-circuit ratio enhancement, neglecting their broader stability and operational benefits. To address this limitation, this study explicitly integrates multi-dimensional stability requirements into synchronous condenser placement to improve overall system security while maintaining acceptable economic performance. To guide optimal deployment, three types of linearized stability constraints are developed and incorporated into the optimization model, namely, nodal inertia, frequency, and voltage stability constraints. The nodal inertia constraint is designed to selectively reinforce inertia-weak areas, while the frequency and voltage stability constraints evaluate the operational stability support performance of the synchronous condenser. The proposed model is formulated as a two-stage stochastic programming framework, in which the first stage optimizes the investment decisions and the second stage performs power system production simulation to evaluate the expected operational cost of the placement decisions under uncertainty. Case studies on a modified IEEE RTS-79 system demonstrate that the proposed approach achieves more than 50 % improvements in key stability metrics, at the expense of an approximately 69.7 M USD increase in total annual system cost compared with the baseline without stability constraints, confirming its effectiveness for resource planning under multiple stability requirements. Sensitivity analyses further highlight the practical trade-offs between electric energy system security and economic efficiency.
{"title":"Enhancing security of high-renewable electric power systems via synchronous condenser placement: A stability-constrained optimization approach","authors":"Yihang Jiang , Shuqiang Zhao , Hui Wang , Chutong Wang , Ming Cheng","doi":"10.1016/j.enconman.2026.121102","DOIUrl":"10.1016/j.enconman.2026.121102","url":null,"abstract":"<div><div>The rapid transition toward low-carbon energy systems with high shares of renewable energy sources has led to declining power system inertia and heightened risks of frequency and voltage instability. Synchronous condensers have emerged as a proven solution to mitigate these challenges, but existing placement strategies mainly focus on short-circuit ratio enhancement, neglecting their broader stability and operational benefits. To address this limitation, this study explicitly integrates multi-dimensional stability requirements into synchronous condenser placement to improve overall system security while maintaining acceptable economic performance. To guide optimal deployment, three types of linearized stability constraints are developed and incorporated into the optimization model, namely, nodal inertia, frequency, and voltage stability constraints. The nodal inertia constraint is designed to selectively reinforce inertia-weak areas, while the frequency and voltage stability constraints evaluate the operational stability support performance of the synchronous condenser. The proposed model is formulated as a two-stage stochastic programming framework, in which the first stage optimizes the investment decisions and the second stage performs power system production simulation to evaluate the expected operational cost of the placement decisions under uncertainty. Case studies on a modified IEEE RTS-79 system demonstrate that the proposed approach achieves more than 50 % improvements in key stability metrics, at the expense of an approximately 69.7 M USD increase in total annual system cost compared with the baseline without stability constraints, confirming its effectiveness for resource planning under multiple stability requirements. Sensitivity analyses further highlight the practical trade-offs between electric energy system security and economic efficiency.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"352 ","pages":"Article 121102"},"PeriodicalIF":10.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033473","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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