Pub Date : 2024-11-17DOI: 10.1016/j.apenergy.2024.124939
Wenxing Jiang , Fangfang Wan , Qiqi Wan , Endao Zhang , Zhenying Chen , Yang Zhang , Jianbin Luo , Yingying Liu , Xiaodong Zhuang , Junliang Zhang , Changchun Ke
Direct borohydride fuel cell (DBFC) has garnered significant interest due to its high energy density. However, the power density remains insufficient for commercial applications. Lots of works have been conducted on the kinetics of the anode reaction, while little attention has been devoted to cathode water management which is important issue for direct liquid fuel cell. Herein, a new structure gas diffusion layer (GDL) with hetero-junction double microporous layer (HJD-MPL) is developed. Utilizing the HJD-MPL structure, achieving a peak power density of 688 mW cm−2 at 80 °C, which exceeds the literature reports (453 mW cm−2). With higher porosity, permeability and stronger gradient capillary force, the oxygen transfer resistance is reduced from 75.5 s cm−1 of commercial GDL to 24.4 s cm−1. This study offers new insight into DBFCs, emphasizing cathode engineering to advance more effective and reliable direct liquid fuel cell technologies.
直接硼氢化燃料电池（DBFC）因其能量密度高而备受关注。然而，其功率密度仍不足以满足商业应用的需要。人们对阳极反应动力学进行了大量研究，却很少关注直接液体燃料电池的重要问题--阴极水管理。在此，我们开发了一种具有异质结双微孔层（HJD-MPL）的新结构气体扩散层（GDL）。利用 HJD-MPL 结构，在 80 °C 时达到了 688 mW cm-2 的峰值功率密度，超过了文献报道（453 mW cm-2）。由于具有更高的孔隙率、渗透性和更强的梯度毛细力，氧气传输阻力从商用 GDL 的 75.5 s cm-1 降至 24.4 s cm-1。这项研究为 DBFCs 提供了新的视角，强调了阴极工程，以推进更有效、更可靠的直接液体燃料电池技术。
{"title":"Boosting the power density of direct borohydride fuel cells to >600 mW cm−2 by cathode water management","authors":"Wenxing Jiang , Fangfang Wan , Qiqi Wan , Endao Zhang , Zhenying Chen , Yang Zhang , Jianbin Luo , Yingying Liu , Xiaodong Zhuang , Junliang Zhang , Changchun Ke","doi":"10.1016/j.apenergy.2024.124939","DOIUrl":"10.1016/j.apenergy.2024.124939","url":null,"abstract":"<div><div>Direct borohydride fuel cell (DBFC) has garnered significant interest due to its high energy density. However, the power density remains insufficient for commercial applications. Lots of works have been conducted on the kinetics of the anode reaction, while little attention has been devoted to cathode water management which is important issue for direct liquid fuel cell. Herein, a new structure gas diffusion layer (GDL) with hetero-junction double microporous layer (HJD-MPL) is developed. Utilizing the HJD-MPL structure, achieving a peak power density of 688 mW cm<sup>−2</sup> at 80 °C, which exceeds the literature reports (453 mW cm<sup>−2</sup>). With higher porosity, permeability and stronger gradient capillary force, the oxygen transfer resistance is reduced from 75.5 s cm<sup>−1</sup> of commercial GDL to 24.4 s cm<sup>−1</sup>. This study offers new insight into DBFCs, emphasizing cathode engineering to advance more effective and reliable direct liquid fuel cell technologies.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124939"},"PeriodicalIF":10.1,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653914","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 : 2024-11-16DOI: 10.1016/j.apenergy.2024.124909
Meng Wang , Senming Wu , Ying Chen, Weiling Luan
Lifespan and safety are the most critical issues for the application of lithium-ion batteries (LIBs). During long-term service, the degradation mechanisms and safety evolution of LIBs remain unclear, posing significant obstacles to battery design and management. This study analyzes the electrochemical degradation mechanisms of LIBs under normal temperature cycling (NTC) and high-temperature cycling (HTC) conditions, linking these mechanisms to the evolution of battery safety. The findings reveal that during NTC, there is a “snowball effect” in performance degradation and safety evolution, leading to sudden death of battery and posing serious safety risks. The degradation pattern of LIBs during NTC and HTC is consistently dominated by the increase of internal resistance and the loss of lithium inventory (LLI). In the aging process, electrolyte consumption and the growth of the solid electrolyte interface (SEI) cause localized lithium plating on the anode, resulting in accelerated capacity decay. However, in batteries subjected to NTC, rapid accumulation of localized lithium plating can trigger a snowball effect, causing electrode deformation, internal short-circuit (ISC) and separator melting. These interacting catastrophic events form a vicious cycle, ultimately leading to battery sudden death and pose significant safety hazards. Additionally, thermal safety analysis reveals the correlation between thermal safety parameters and state of health (SOH), quantifying the thermal safety degradation caused by sudden death. Sudden death directly alters the evolution pattern of battery safety, leading to a severe decline in battery safety. These findings offer new insights into potential safety hazards associated with long-term use of LIBs.
{"title":"The snowball effect in electrochemical degradation and safety evolution of lithium-ion batteries during long-term cycling","authors":"Meng Wang , Senming Wu , Ying Chen, Weiling Luan","doi":"10.1016/j.apenergy.2024.124909","DOIUrl":"10.1016/j.apenergy.2024.124909","url":null,"abstract":"<div><div>Lifespan and safety are the most critical issues for the application of lithium-ion batteries (LIBs). During long-term service, the degradation mechanisms and safety evolution of LIBs remain unclear, posing significant obstacles to battery design and management. This study analyzes the electrochemical degradation mechanisms of LIBs under normal temperature cycling (NTC) and high-temperature cycling (HTC) conditions, linking these mechanisms to the evolution of battery safety. The findings reveal that during NTC, there is a “snowball effect” in performance degradation and safety evolution, leading to sudden death of battery and posing serious safety risks. The degradation pattern of LIBs during NTC and HTC is consistently dominated by the increase of internal resistance and the loss of lithium inventory (LLI). In the aging process, electrolyte consumption and the growth of the solid electrolyte interface (SEI) cause localized lithium plating on the anode, resulting in accelerated capacity decay. However, in batteries subjected to NTC, rapid accumulation of localized lithium plating can trigger a snowball effect, causing electrode deformation, internal short-circuit (ISC) and separator melting. These interacting catastrophic events form a vicious cycle, ultimately leading to battery sudden death and pose significant safety hazards. Additionally, thermal safety analysis reveals the correlation between thermal safety parameters and state of health (SOH), quantifying the thermal safety degradation caused by sudden death. Sudden death directly alters the evolution pattern of battery safety, leading to a severe decline in battery safety. These findings offer new insights into potential safety hazards associated with long-term use of LIBs.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124909"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653945","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 : 2024-11-16DOI: 10.1016/j.apenergy.2024.124834
Jingjing Wang , Liangzhong Yao , Jun Liang , Jun Wang , Fan Cheng
The integration of a large number of distributed resources into an active distribution network presents significant challenges, including high control dimensionality, strong output uncertainty, and low utilization of renewable energy. This paper introduces a distributed optimization strategy for networked microgrids based on network partitioning to alleviate the computational burden, reduce operating costs, and enhance the utilization of renewable energy. The active distribution network is partitioned into networked microgrids, and a two-layer distributed optimization model is developed for their management. The first layer focuses on intra-day distributed optimal dispatch, balancing power and load by managing various flexible resources and the exchange power between virtual microgrids. The second layer, real-time distributed power tracking optimization, coordinates flexible resources within virtual microgrids to mitigate photovoltaic power fluctuations and track intra-day dispatch instructions. Simulation results demonstrate that the proposed network partitioning method reduces dispatch costs by 5.3 % and increases the utilization of distributed PV by 3 %, compared to the NP method that only considering modularity. Moreover, calculation times for intra-day dispatch and real-time power tracking are reduced by approximately 26 % and 50 %, respectively, compared to centralized control.
{"title":"Distributed optimization strategy for networked microgrids based on network partitioning","authors":"Jingjing Wang , Liangzhong Yao , Jun Liang , Jun Wang , Fan Cheng","doi":"10.1016/j.apenergy.2024.124834","DOIUrl":"10.1016/j.apenergy.2024.124834","url":null,"abstract":"<div><div>The integration of a large number of distributed resources into an active distribution network presents significant challenges, including high control dimensionality, strong output uncertainty, and low utilization of renewable energy. This paper introduces a distributed optimization strategy for networked microgrids based on network partitioning to alleviate the computational burden, reduce operating costs, and enhance the utilization of renewable energy. The active distribution network is partitioned into networked microgrids, and a two-layer distributed optimization model is developed for their management. The first layer focuses on intra-day distributed optimal dispatch, balancing power and load by managing various flexible resources and the exchange power between virtual microgrids. The second layer, real-time distributed power tracking optimization, coordinates flexible resources within virtual microgrids to mitigate photovoltaic power fluctuations and track intra-day dispatch instructions. Simulation results demonstrate that the proposed network partitioning method reduces dispatch costs by 5.3 % and increases the utilization of distributed PV by 3 %, compared to the NP method that only considering modularity. Moreover, calculation times for intra-day dispatch and real-time power tracking are reduced by approximately 26 % and 50 %, respectively, compared to centralized control.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124834"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653943","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 : 2024-11-16DOI: 10.1016/j.apenergy.2024.124823
Qinru Hu , Simon Hu , Shiyu Shen , Yanfeng Ouyang , Xiqun (Michael) Chen
This paper focuses on optimizing the routing and charging schedules of an autonomous electric taxi (AET) system integrated with mobile charging services. In this system, a fleet of AETs provides on-demand ride services for customers, while mobile charging vehicles (MCVs) are deployed as a flexible complement to fixed charging stations, offering fast charging options for AETs. A dynamic programming model is developed to optimize the joint operations of AETs and MCVs, considering stochastics in customer demand, AET energy consumption, and charging station resources. The objective is to maximize the operator’s overall profit over the entire planning horizon, including revenues from serving customer requests, travel costs, charging costs, and penalties associated with both fleets. To address the stochastic and dynamic nature of the problem, an approximate dynamic programming (ADP) approach, incorporating customized pruning strategies to reduce the state and decision space, is proposed. This approach balances immediate operational gains with future potential profits. A series of numerical experiments have been conducted to evaluate the effectiveness of the proposed model and algorithm. Results show that the ADP-based policy significantly improves system performance compared to classical myopic benchmarks.
本文的重点是优化集成了移动充电服务的自动电动出租车（AET）系统的路线和充电时间表。在该系统中，自动电动出租车队为客户提供按需乘车服务，而移动充电车（MCV）则作为固定充电站的灵活补充部署，为自动电动出租车提供快速充电选择。考虑到客户需求、AET 能源消耗和充电站资源的随机性，我们开发了一个动态编程模型来优化 AET 和 MCV 的联合运营。目标是使运营商在整个规划期限内的整体利润最大化，包括服务客户需求的收入、旅行成本、充电成本以及与两支车队相关的罚款。为解决该问题的随机性和动态性，我们提出了一种近似动态编程（ADP）方法，该方法结合了定制的剪枝策略，以缩小状态和决策空间。这种方法兼顾了眼前的运营收益和未来的潜在利润。为了评估所提出的模型和算法的有效性，我们进行了一系列数值实验。结果表明，与传统的近视基准相比，基于 ADP 的策略大大提高了系统性能。
{"title":"Optimizing autonomous electric taxi operations with integrated mobile charging services: An approximate dynamic programming approach","authors":"Qinru Hu , Simon Hu , Shiyu Shen , Yanfeng Ouyang , Xiqun (Michael) Chen","doi":"10.1016/j.apenergy.2024.124823","DOIUrl":"10.1016/j.apenergy.2024.124823","url":null,"abstract":"<div><div>This paper focuses on optimizing the routing and charging schedules of an autonomous electric taxi (AET) system integrated with mobile charging services. In this system, a fleet of AETs provides on-demand ride services for customers, while mobile charging vehicles (MCVs) are deployed as a flexible complement to fixed charging stations, offering fast charging options for AETs. A dynamic programming model is developed to optimize the joint operations of AETs and MCVs, considering stochastics in customer demand, AET energy consumption, and charging station resources. The objective is to maximize the operator’s overall profit over the entire planning horizon, including revenues from serving customer requests, travel costs, charging costs, and penalties associated with both fleets. To address the stochastic and dynamic nature of the problem, an approximate dynamic programming (ADP) approach, incorporating customized pruning strategies to reduce the state and decision space, is proposed. This approach balances immediate operational gains with future potential profits. A series of numerical experiments have been conducted to evaluate the effectiveness of the proposed model and algorithm. Results show that the ADP-based policy significantly improves system performance compared to classical myopic benchmarks.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124823"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653944","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 : 2024-11-16DOI: 10.1016/j.apenergy.2024.124875
Zhixiang Cheng , Yuanyuan Min , Peng Qin , Yue Zhang , Junyuan Li , Wenxin Mei , Qingsong Wang
The inner pressure that increases due to the complex physical and chemical reactions of batteries plays an important role in thermal runaway early warning and gas injection. However, most of the current thermal-pressure coupling models for batteries cannot accurately describe the gas generation sources and predict the inner pressure increases of multiple jelly rolls. In this work, we propose a thermal-pressure coupling model by combining the gas composition data and the fitting data from the accelerating rate calorimeter experiment. The electrolyte vapor pressure and internal gas composition are obtained under uniform heating conditions. The internal pressure growth source relies on the variation in the gas composition at different temperature ranges to infer. The reaction kinetics equations are then combined with gas generation sources, energy conservation equations and venting process to form a thermal-pressure model, which adopts a distributed structure to adapt to the temperature gradient between jelly rolls. The simulation results indicate that the model can accurately match the reaction gas accumulation phase before the valve venting, as well as the thermal runaway and cooling process temperature after the ejection. The simulation results indicate that when the pressure threshold increases from 0.5 MPa to 0.75 MPa, both the time-to-venting and time-to-peak temperature increase, but the interval between them decreases. Additionally, the explosion concentration range of the mixture gas also increases accordingly. This model revealed the inner pressure increase and thermal runaway process in large-format lithium iron phosphate batteries, offering guidance for early warning and safety design.
{"title":"A distributed thermal-pressure coupling model of large-format lithium iron phosphate battery thermal runaway","authors":"Zhixiang Cheng , Yuanyuan Min , Peng Qin , Yue Zhang , Junyuan Li , Wenxin Mei , Qingsong Wang","doi":"10.1016/j.apenergy.2024.124875","DOIUrl":"10.1016/j.apenergy.2024.124875","url":null,"abstract":"<div><div>The inner pressure that increases due to the complex physical and chemical reactions of batteries plays an important role in thermal runaway early warning and gas injection. However, most of the current thermal-pressure coupling models for batteries cannot accurately describe the gas generation sources and predict the inner pressure increases of multiple jelly rolls. In this work, we propose a thermal-pressure coupling model by combining the gas composition data and the fitting data from the accelerating rate calorimeter experiment. The electrolyte vapor pressure and internal gas composition are obtained under uniform heating conditions. The internal pressure growth source relies on the variation in the gas composition at different temperature ranges to infer. The reaction kinetics equations are then combined with gas generation sources, energy conservation equations and venting process to form a thermal-pressure model, which adopts a distributed structure to adapt to the temperature gradient between jelly rolls. The simulation results indicate that the model can accurately match the reaction gas accumulation phase before the valve venting, as well as the thermal runaway and cooling process temperature after the ejection. The simulation results indicate that when the pressure threshold increases from 0.5 MPa to 0.75 MPa, both the time-to-venting and time-to-peak temperature increase, but the interval between them decreases. Additionally, the explosion concentration range of the mixture gas also increases accordingly. This model revealed the inner pressure increase and thermal runaway process in large-format lithium iron phosphate batteries, offering guidance for early warning and safety design.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124875"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653862","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}
Capacity expansion optimisation is a widely used techno-economic analysis particularly on topics related to climate change mitigation and renewable energy transition. Using optimisation models to investigate capacity expansion in regions that potentially require significant grid infrastructure development requires incorporation of grid expansion problem within the optimisation. This study presents the development of SELARU, a spatially explicit optimisation model that incorporates the economies of scale of grid expansion using contextualized geographical feature to form the model's high-resolution spatial units. The model is used to investigate the case study of Indonesia using various spatial treatments to demonstrate the impact of detailed spatial depiction of grid expansion. Results reveal significant difference in renewable energy deployment trajectory (up to 2272 % increase in new generation capacity) between high-resolution spatial depiction of grid expansion vis-à-vis non spatially explicit energy system optimisation. Due to its high-resolution, SELARU also generates detailed information on the geographical extent of grid expansion requirement, which provides more realistic insights on governance challenges of renewable energy transition. Careful consideration of spatial representation is crucial when optimisation model is used to evaluate scenarios that concern technology selection such as renewable energy deployment or climate change mitigation.
{"title":"Incorporating grid development in capacity expansion optimisation - a case study for Indonesia","authors":"Bintang Yuwono , Lukas Kranzl , Reinhard Haas , Retno Gumilang Dewi , Ucok Welo Risma Siagian , Florian Kraxner , Ping Yowargana","doi":"10.1016/j.apenergy.2024.124837","DOIUrl":"10.1016/j.apenergy.2024.124837","url":null,"abstract":"<div><div>Capacity expansion optimisation is a widely used techno-economic analysis particularly on topics related to climate change mitigation and renewable energy transition. Using optimisation models to investigate capacity expansion in regions that potentially require significant grid infrastructure development requires incorporation of grid expansion problem within the optimisation. This study presents the development of SELARU, a spatially explicit optimisation model that incorporates the economies of scale of grid expansion using contextualized geographical feature to form the model's high-resolution spatial units. The model is used to investigate the case study of Indonesia using various spatial treatments to demonstrate the impact of detailed spatial depiction of grid expansion. Results reveal significant difference in renewable energy deployment trajectory (up to 2272 % increase in new generation capacity) between high-resolution spatial depiction of grid expansion vis-à-vis non spatially explicit energy system optimisation. Due to its high-resolution, SELARU also generates detailed information on the geographical extent of grid expansion requirement, which provides more realistic insights on governance challenges of renewable energy transition. Careful consideration of spatial representation is crucial when optimisation model is used to evaluate scenarios that concern technology selection such as renewable energy deployment or climate change mitigation.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124837"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.apenergy.2024.124848
Xiang Cheng , Jin Lin , Mingjun Zhang , Liandong Sha , Bosen Yang , Feng Liu , Yonghua Song
The ability of the electrolysis system, powered by fluctuating and intermittent renewable sources, to rapidly and accurately track power signals is crucial for energy management in renewable power-to-hydrogen (ReP2H) plants and for providing grid frequency regulation as a virtual power plant (VPP). However, there is a considerable lag (several seconds or even more than 20 s) between the changes of the stack power compared with the stack current, mainly due to the existence of the electric double-layer (EDL) effect. This characteristic hinders the further application of electrolysis systems as flexible loads in power grids. By designing a suitable power controller in the power-electronics interface directly connected to the stack to replace the traditional current controller, it is expected to improve the fast dynamic response of the stack power. This paper proposes a unified electrical equivalent circuit for alkaline water electrolysis (AWE) systems and proton exchange membrane (PEM) electrolysis system with detailed parallel Buck type DC/DC interface, which considers the EDL effect and nonlinear behaviors of electrolysis systems and is suitable for controller design. A power controller design and robust parameter tuning method without excessive current overshoot based on frequency-domain analysis is proposed. The accuracy and effectiveness of the proposed model and method are verified by the experimental test on the 2 N m/h(10 kW) AWE system and the 1 N m/h(5 kW) PEM electrolysis system. With the proposed power controller, the AWE and PEM electrolysis system can change the stack power within 0.266s and 0.21s respectively, meeting the requirements of energy management and frequency regulation. Additionally, the temperature stability and the sensitivity of the proposed method to parameter fluctuations in the stack and DC/DC interface are analyzed.
{"title":"Power controller design for electrolysis systems with DC/DC interface supporting fast dynamic operation: A model-based and experimental study","authors":"Xiang Cheng , Jin Lin , Mingjun Zhang , Liandong Sha , Bosen Yang , Feng Liu , Yonghua Song","doi":"10.1016/j.apenergy.2024.124848","DOIUrl":"10.1016/j.apenergy.2024.124848","url":null,"abstract":"<div><div>The ability of the electrolysis system, powered by fluctuating and intermittent renewable sources, to rapidly and accurately track power signals is crucial for energy management in renewable power-to-hydrogen (ReP2H) plants and for providing grid frequency regulation as a virtual power plant (VPP). However, there is a considerable lag (several seconds or even more than 20 s) between the changes of the stack power compared with the stack current, mainly due to the existence of the electric double-layer (EDL) effect. This characteristic hinders the further application of electrolysis systems as flexible loads in power grids. By designing a suitable power controller in the power-electronics interface directly connected to the stack to replace the traditional current controller, it is expected to improve the fast dynamic response of the stack power. This paper proposes a unified electrical equivalent circuit for alkaline water electrolysis (AWE) systems and proton exchange membrane (PEM) electrolysis system with detailed parallel Buck type DC/DC interface, which considers the EDL effect and nonlinear behaviors of electrolysis systems and is suitable for controller design. A power controller design and robust parameter tuning method without excessive current overshoot based on frequency-domain analysis is proposed. The accuracy and effectiveness of the proposed model and method are verified by the experimental test on the 2 N m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>/h(10 kW) AWE system and the 1 N m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>/h(5 kW) PEM electrolysis system. With the proposed power controller, the AWE and PEM electrolysis system can change the stack power within 0.266s and 0.21s respectively, meeting the requirements of energy management and frequency regulation. Additionally, the temperature stability and the sensitivity of the proposed method to parameter fluctuations in the stack and DC/DC interface are analyzed.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124848"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654009","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 : 2024-11-16DOI: 10.1016/j.apenergy.2024.124874
Yulin Wang , Lixia Qi , Fei Ma , Hua Li , Shuai Ma , Cheng Wang , Wei He , Shixue Wang
The optimal design of platinum (Pt) particles distribution within catalyst layer (CL) favors their utilization and the polymer electrolyte membrane fuel cell (PEMFC) performance. A stochastic algorithm is employed in this study to reconstruct the 2D microstructure of the CL by considering the random distribution of carbon carriers and ionomers and a novel double-gradient distribution of Pt particles. The double-gradient Pt-distributed CLs feature double dividend regions of equal and unequal lengths. Subsequently, the reaction transport process within these double-gradient CLs is numerically investigated by a lattice Boltzmann (LB) method. The numerical results indicate that the reaction transport process within the double-gradient CLs differs greatly from that within conventional CLs. With the total Pt particle number constant, increasing the Pt particle number within the inlet region of the CL initially improves and consequently degrades the oxygen reduce reaction (ORR), whereas a reverse design always leads to a reduced ORR. The optimal CL gradient for double dividend regions of equal length occurs when the ratio of Pt particle number in the inlet region to that in the outlet region (Ptin:Ptout) is 5:1, which leads to a 28.85 % increase in the ORR rate compared with that of the conventional CL. Moreover, for the gradient CL with double dividend regions of unequal length, we find that the optimal ratios of Lin:Lout and Ptin:Ptout are 1:4 and 6:1, respectively; this gradient CL yields a 58.65 % increase in the ORR compared with that of the conventional CL.
{"title":"Optimization of a catalyst layer with a high-utilization gradient Pt distribution for polymer electrolyte membrane fuel cells","authors":"Yulin Wang , Lixia Qi , Fei Ma , Hua Li , Shuai Ma , Cheng Wang , Wei He , Shixue Wang","doi":"10.1016/j.apenergy.2024.124874","DOIUrl":"10.1016/j.apenergy.2024.124874","url":null,"abstract":"<div><div>The optimal design of platinum (Pt) particles distribution within catalyst layer (CL) favors their utilization and the polymer electrolyte membrane fuel cell (PEMFC) performance. A stochastic algorithm is employed in this study to reconstruct the 2D microstructure of the CL by considering the random distribution of carbon carriers and ionomers and a novel double-gradient distribution of Pt particles. The double-gradient Pt-distributed CLs feature double dividend regions of equal and unequal lengths. Subsequently, the reaction transport process within these double-gradient CLs is numerically investigated by a lattice Boltzmann (LB) method. The numerical results indicate that the reaction transport process within the double-gradient CLs differs greatly from that within conventional CLs. With the total Pt particle number constant, increasing the Pt particle number within the inlet region of the CL initially improves and consequently degrades the oxygen reduce reaction (ORR), whereas a reverse design always leads to a reduced ORR. The optimal CL gradient for double dividend regions of equal length occurs when the ratio of Pt particle number in the inlet region to that in the outlet region (Pt<sub>in</sub>:Pt<sub>out</sub>) is 5:1, which leads to a 28.85 % increase in the ORR rate compared with that of the conventional CL. Moreover, for the gradient CL with double dividend regions of unequal length, we find that the optimal ratios of <em>L</em><sub>in</sub>:<em>L</em><sub>out</sub> and Pt<sub>in</sub>:Pt<sub>out</sub> are 1:4 and 6:1, respectively; this gradient CL yields a 58.65 % increase in the ORR compared with that of the conventional CL.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124874"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654010","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 : 2024-11-16DOI: 10.1016/j.apenergy.2024.124921
Shehab Osama , Hamdy Hassan , Mohamed Emam
This study focuses on enhancing the efficiency of vertical axis Savonius Hydrokinetic turbines designed for marine applications, historically characterized by a power coefficient below 0.1. Prior efforts aimed at improving rotor performance have primarily involved modifications to blade designs. In this article, a new approach is introduced, incorporating twisted blades inspired by the Archimedes screw turbine. Utilizing a 3D incompressible flow analysis based on the Navier-Stokes equation, this research explores and compares the turbine's effectiveness with varying screw pitches (0.5, 0.75, 1). The system of equations is solved numerically using ANSYS 2020 R2 fluid fluent. The performance assessment involves contrasting each proposed rotor against a pitchless semi-circle rotor. An innovative aspect of this work involves investigating the impact of asymmetry using two different ratios (2:1 and 3:1). Specifically, the lower half of the optimal pitch screw remains constant, while the upper half varies based on these ratios. To understand performance trends, the study employs visualizations of pressure, velocity contours, and streamlines to grasp the flow field and its underlying principles. Turbulent kinetic energy and eddy viscosity are also visualized. The results reveal an 18.25 % improvement in performance with the proposed rotor featuring a pitch screw of 0.5. Notably, the asymmetric rotor with a 2:1 ratio demonstrates the highest performance. According to the ANN, the optimum pitch screw value is determined to be 0.6, achieving a power coefficient of 0.1938. This investigation employs novel design modifications and asymmetrical configurations, offering valuable insights into significantly enhancing the performance of Savonius turbines for marine applications.
{"title":"Optimization and parametric analysis of a novel design of Savonius hydrokinetic turbine using artificial neural network","authors":"Shehab Osama , Hamdy Hassan , Mohamed Emam","doi":"10.1016/j.apenergy.2024.124921","DOIUrl":"10.1016/j.apenergy.2024.124921","url":null,"abstract":"<div><div>This study focuses on enhancing the efficiency of vertical axis Savonius Hydrokinetic turbines designed for marine applications, historically characterized by a power coefficient below 0.1. Prior efforts aimed at improving rotor performance have primarily involved modifications to blade designs. In this article, a new approach is introduced, incorporating twisted blades inspired by the Archimedes screw turbine. Utilizing a 3D incompressible flow analysis based on the Navier-Stokes equation, this research explores and compares the turbine's effectiveness with varying screw pitches (0.5, 0.75, 1). The system of equations is solved numerically using ANSYS 2020 R2 fluid fluent. The performance assessment involves contrasting each proposed rotor against a pitchless semi-circle rotor. An innovative aspect of this work involves investigating the impact of asymmetry using two different ratios (2:1 and 3:1). Specifically, the lower half of the optimal pitch screw remains constant, while the upper half varies based on these ratios. To understand performance trends, the study employs visualizations of pressure, velocity contours, and streamlines to grasp the flow field and its underlying principles. Turbulent kinetic energy and eddy viscosity are also visualized. The results reveal an 18.25 % improvement in performance with the proposed rotor featuring a pitch screw of 0.5. Notably, the asymmetric rotor with a 2:1 ratio demonstrates the highest performance. According to the ANN, the optimum pitch screw value is determined to be 0.6, achieving a power coefficient of 0.1938. This investigation employs novel design modifications and asymmetrical configurations, offering valuable insights into significantly enhancing the performance of Savonius turbines for marine applications.</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124921"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653912","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 : 2024-11-16DOI: 10.1016/j.apenergy.2024.124905
Yongpan Chen, Jinghan Zhao, Keting Wan, Miao Yu
A microgrid cluster (MGC) is formed by interconnected geographically adjacent microgrids (MGs), which can effectively improve power supply reliability. To fulfill the requirements of coordination between MGs while exerting the autonomy ability of each MG, this paper proposes a hierarchical distributed control method for DC MGCs with MG autonomous-cooperative mode switching. The proposed method can not only realize the proportional current sharing between the MGs and the voltage regulation of the common bus but also allow MGs to operate in autonomous or cooperative mode by establishing and disconnecting the inter-MG communication links. In addition, considering that the delay of inter-MG communication links affects multiple control links of the proposed control method, a delay-dependent stability analysis method based on Padé approximation and eigenvalue spectrum comparison is proposed. By stability analysis, the time delay margin (TDM) is determined, and the key link that determines the TDM is identified as the observer based on the proportional-integral (PI) consensus algorithm. On this basis, the scattering transformation (ST) is introduced to improve the stability of the observer under delay and thus enhance the TDM of DC MGCs, which is confirmed by stability analysis based on a new system model integrating node variables and edge variables. Finally, the performance of the proposed control method and stability analysis results are verified by hardware-in-loop (HIL) tests and MATLAB/Simulink simulations
{"title":"Delay-tolerant hierarchical distributed control for DC microgrid clusters considering microgrid autonomy","authors":"Yongpan Chen, Jinghan Zhao, Keting Wan, Miao Yu","doi":"10.1016/j.apenergy.2024.124905","DOIUrl":"10.1016/j.apenergy.2024.124905","url":null,"abstract":"<div><div>A microgrid cluster (MGC) is formed by interconnected geographically adjacent microgrids (MGs), which can effectively improve power supply reliability. To fulfill the requirements of coordination between MGs while exerting the autonomy ability of each MG, this paper proposes a hierarchical distributed control method for DC MGCs with MG autonomous-cooperative mode switching. The proposed method can not only realize the proportional current sharing between the MGs and the voltage regulation of the common bus but also allow MGs to operate in autonomous or cooperative mode by establishing and disconnecting the inter-MG communication links. In addition, considering that the delay of inter-MG communication links affects multiple control links of the proposed control method, a delay-dependent stability analysis method based on Padé approximation and eigenvalue spectrum comparison is proposed. By stability analysis, the time delay margin (TDM) is determined, and the key link that determines the TDM is identified as the observer based on the proportional-integral (PI) consensus algorithm. On this basis, the scattering transformation (ST) is introduced to improve the stability of the observer under delay and thus enhance the TDM of DC MGCs, which is confirmed by stability analysis based on a new system model integrating node variables and edge variables. Finally, the performance of the proposed control method and stability analysis results are verified by hardware-in-loop (HIL) tests and MATLAB/Simulink simulations</div></div>","PeriodicalId":246,"journal":{"name":"Applied Energy","volume":"378 ","pages":"Article 124905"},"PeriodicalIF":10.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653913","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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