The initial micro-cracks affect the evolution characteristics of macroscopic deformation and failure of rock but are often ignored in theoretical calculation,numerical simulation,and mechanical experiments.In this stu...The initial micro-cracks affect the evolution characteristics of macroscopic deformation and failure of rock but are often ignored in theoretical calculation,numerical simulation,and mechanical experiments.In this study,we propose a quantitative analysis model to investigate the effects of initial micro-cracks on the evolution of marble deformation and failure.The relationship between the micro-crack propagation and the marble failure characteristics was comprehensively studied by combining theoretical analysis with a micro-computed tomography(micro-CT)scanning technique.We found that with the increase of confining pressure,the matrix elastic modulus of the marble first increased and then tended to be stable,while the micro-cracks increased exponentially.The sensitivity ranges of the marble sample matrix elastic modulus and micro-cracks to confining pressure were 0–30 MPa and 30–50 MPa,respectively.The porosity and Poisson’s ratio decreased exponentially.The increasing proportion of internal micro-cracks led to an increase in the sample non-uniformity.The samples presented mainly shear failure under triaxial compression,and the failure angle decreased linearly with the increase of confining pressure.The convergence direction of cracks decreased gradually.This quantitative analysis model could accurately portray the relationship between the overall macroscopic deformation and the deviatoric stress of the samples at the compaction and the linear elastic stages,thus deepening the understanding of the stress–strain behavior of rocks.展开更多
It is anticipated that alkaline water electrolysis(AWE)technology will assume a significant role in the future energy sector,facilitating the integration of renewable energy and hydrogen production.Regrettably,the eff...It is anticipated that alkaline water electrolysis(AWE)technology will assume a significant role in the future energy sector,facilitating the integration of renewable energy and hydrogen production.Regrettably,the effi-ciency of AWE is not yet optimal.In particular,the inefficiency caused by bubbles at increased current density is often overlooked,necessitating a detailed understanding of the intricate relationship between bubble evolution and electrolytic reactions.This paper presents a comprehensive review of the fundamental theory and recent research on bubbles,and outlines the primary challenges and research directions for bubble dynamics in AWE.First,the theory of bubble nucleation,growth,and detachment is reviewed and summarized.Subsequently,the impact of bubbles on the diverse processes occurring during the electrolysis reaction is meticulously delineated and examined.The following section presents a thorough compilation and categorization of the methods employed to remove bubbles,with a detailed analysis of the strategies deployed to mitigate the impact of gas bubble traffic.Additionally,an in-depth exploration of the research methodology employed at each stage of the bubble evolution process is provided.Finally,the review concludes with a summary and outlook on the oppor-tunities and challenges associated with studying bubble dynamics in AWE,offering insights into innovative av-enues for efficient electrolytic hydrogen production.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12272119 and U1965101).
文摘The initial micro-cracks affect the evolution characteristics of macroscopic deformation and failure of rock but are often ignored in theoretical calculation,numerical simulation,and mechanical experiments.In this study,we propose a quantitative analysis model to investigate the effects of initial micro-cracks on the evolution of marble deformation and failure.The relationship between the micro-crack propagation and the marble failure characteristics was comprehensively studied by combining theoretical analysis with a micro-computed tomography(micro-CT)scanning technique.We found that with the increase of confining pressure,the matrix elastic modulus of the marble first increased and then tended to be stable,while the micro-cracks increased exponentially.The sensitivity ranges of the marble sample matrix elastic modulus and micro-cracks to confining pressure were 0–30 MPa and 30–50 MPa,respectively.The porosity and Poisson’s ratio decreased exponentially.The increasing proportion of internal micro-cracks led to an increase in the sample non-uniformity.The samples presented mainly shear failure under triaxial compression,and the failure angle decreased linearly with the increase of confining pressure.The convergence direction of cracks decreased gradually.This quantitative analysis model could accurately portray the relationship between the overall macroscopic deformation and the deviatoric stress of the samples at the compaction and the linear elastic stages,thus deepening the understanding of the stress–strain behavior of rocks.
基金support from National Natural Science Foundation of China,Grant Nos.52241701 and 52307249Shanghai Pujiang Program,Nos.22PJ1413100Fundamental Research Funds for the Central Universities at Tongji University,Nos.PA22120220426.
文摘It is anticipated that alkaline water electrolysis(AWE)technology will assume a significant role in the future energy sector,facilitating the integration of renewable energy and hydrogen production.Regrettably,the effi-ciency of AWE is not yet optimal.In particular,the inefficiency caused by bubbles at increased current density is often overlooked,necessitating a detailed understanding of the intricate relationship between bubble evolution and electrolytic reactions.This paper presents a comprehensive review of the fundamental theory and recent research on bubbles,and outlines the primary challenges and research directions for bubble dynamics in AWE.First,the theory of bubble nucleation,growth,and detachment is reviewed and summarized.Subsequently,the impact of bubbles on the diverse processes occurring during the electrolysis reaction is meticulously delineated and examined.The following section presents a thorough compilation and categorization of the methods employed to remove bubbles,with a detailed analysis of the strategies deployed to mitigate the impact of gas bubble traffic.Additionally,an in-depth exploration of the research methodology employed at each stage of the bubble evolution process is provided.Finally,the review concludes with a summary and outlook on the oppor-tunities and challenges associated with studying bubble dynamics in AWE,offering insights into innovative av-enues for efficient electrolytic hydrogen production.
