This article is aimed to experimentally validate the beneficial effects of boundary layer suction on improving the aerodynamic performance of a compressor cascade with a large camber angle. The flow field of the casca...This article is aimed to experimentally validate the beneficial effects of boundary layer suction on improving the aerodynamic performance of a compressor cascade with a large camber angle. The flow field of the cascade is measured and the ink-trace flow visualization is also presented. The experimental results show that the boundary layer suction reduces losses near the area of rnidspan in the cascade most effectively for all suction cases under test. Losses of the endwall could remarkably decrease only when the suction is at the position where the boundary layer has separated but still not departed far away from the blade surface. It is evidenced that the higher suction flow rate and the suction position closer to the trailing edge result in greater reduction in losses and the maximum reduction in the total pressure loss accounts to 16.5% for all cases. The suction position plays a greater role in affecting the total pressure loss than the suction flow rate does.展开更多
In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex ge...In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex generator with a special configuration and the longitudinal suction slot are adopted. The calculated results show that a reverse flow region, which is considered the main reason for occurring stall at 7.9° incidence, grows and collapses rapidly near the leading edge and leads to two critical points occurring on the end-wall with the increasing incidence in the baseline. As the micro-vortex generator is introduced in the baseline cascade, the corner separation is switched to a trailing edge separation by the thrust from the induced vortex. Meanwhile, the occurrence of failure is delayed due to the mixed low energy fluid and main flow. The synergistic effects between the micro-vortex generator and the boundary layer suction on the performance of the cascade are superior to the baseline at all the incidence conditions before the occurrence of failure, and the sudden deterioration of the cascade occurs at 10.3° incidence. The optimal results show that the farther upstream suction position, the lower total pressure loss of the cascade with vortex generator at the near stall condition. Moreover, the induced vortex with a leg can migrate the accumulated low energy fluid backward to delay the occurrence of stall.展开更多
It is well known that single-atom catalysts(SACs)have become a hot topic in the field of catalysis due to their advantages such as 100%metal atom utilization efficiency,high catalytic activity and selectivity compared...It is well known that single-atom catalysts(SACs)have become a hot topic in the field of catalysis due to their advantages such as 100%metal atom utilization efficiency,high catalytic activity and selectivity compared with conventional catalysts and nanocatalysts.However,the isolated metal atoms on SACs have thermodynamic instability and tend to agglomerate,which limit their catalytic performance.Therefore,it is of great significance to synthesize stable and high-loading single-atom catalysts(HLSACs).In this paper,we review the research progress of HLSACs from two aspects:design and application.Firstly,we comprehensively introduce the synthesis strategies of HLSACs,namely,top-down and bottom-up methods.Secondly,we overview the application status of HLSACs in three fields:electrocatalysis,thermal catalysis and photocatalysis.Finally,we summarize the development prospects and challenges of HLSACs.展开更多
Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loadin...Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loading Fe-SA catalysts by a simple procedure remains challenging.Herein,we report a high-loading(7.5 wt%)Fe-SA/NPC catalyst prepared by carbon-assisted pyrolysis of metal complexes.Both the nitrogen-doped porous carbon(NPC)support with high specific surface area and ο-phenylenediamine(o-PD)play key roles role in the preparation of high-loading Fe-SA/NPC catalysts.The results of X-ray photoelectron spectroscopy,high-angle annular dark-field scanning transmission electron microscopy,and X-ray absorption fine structure spectroscopy experiments show that the Fe atoms are anchored on the carbon carriers in a single-atom site configuration and coordinated with four of the doped nitrogen atoms of the carbon substrates(Fe-N_(4)).The activities of the Fe-SA/NPC catalysts in the oxygen reduction reaction increased with increasing iron loading.The optimized 250Fe-SA/NPC-800 catalyst exhibited an onset potential 0.97 V of and a half-wave potential of 0.85 V.Our study provides a simple approach for the large-scale synthesis of high-loading single-atom catalysts.展开更多
Sulfur utilization improvement and control of dissolved lithium polysulfide(LiPS;Li_(2)S x,2<x≤8)are cru-cial aspects of the development of lithium-sulfur(Li-S)batteries,especially in high-loading sulfur elec-trode...Sulfur utilization improvement and control of dissolved lithium polysulfide(LiPS;Li_(2)S x,2<x≤8)are cru-cial aspects of the development of lithium-sulfur(Li-S)batteries,especially in high-loading sulfur elec-trodes and low electrolyte/sulfur(E/S)ratios.The sluggish reaction in the low E/S ratio induces poor LiPS solubility and unstable Li_(2)S electrodeposition,resulting in limited sulfur utilization,especially under high-loading sulfur electrode.In this study,we report on salt concentration effects that improve sulfur utilization with a high-loading cathode(6 mgs ulfurcm^(-2)),a high sulfur content(80 wt%)and a low E/S ratio(5 m L gs ulfur^(-1)).On the basis of the rapid LiPS dissolving in a low concentration electrolyte,we estab-lished that the quantity of Li_(2)S electrodeposition from a high Li+diffusion coefficient,referring to the reduction of LiPS precipitation,was significantly enhanced by a faster kinetic.These results demonstrate the importance of kinetic factors for the rate capability and cycle life stability of Li-S battery electrolytes through high Li_(2)S deposition under high-loading sulfur electrode.展开更多
An effect of Mg introduction on efficiency of high-loaded nickel catalysts in dehydrogenation of decahydroquinoline(10HQ)was inves-tigated.10HQ dehydrogenation is key process for the liquid organic hydrogen carrier(LO...An effect of Mg introduction on efficiency of high-loaded nickel catalysts in dehydrogenation of decahydroquinoline(10HQ)was inves-tigated.10HQ dehydrogenation is key process for the liquid organic hydrogen carrier(LOHC)storage technology using the quinoline/10HQ pair as H_(2)-lean/H_(2)-rich substrates.An influence of synthesis technique of Ni/Mg/Al catalysts on their properties has been demonstrated.The catalysts were synthesized through coprecipitation of Ni,Mg,Al precursors to obtain layered double hydroxides(LDH)or via syn-thesis of(∼72 wt%)Ni-Al_(2)O_(3) system-also through coprecipitation,followed by modifying with a magnesium-containing precursor.For the catalysts of the first series,the inclusion of magnesium into LDH lattice led to a significant increase in catalytic activity in hydrogen extraction(10HQ dehydrogenation reaction).Despite the decrease in the content of catalytically active nickel,a significant increase in the yield of the dehydrogenation product was observed.This regularity is presumably associated with appearance of basic sites,that accelerates the dehydrogenation reaction.In the case of the second series,activity of pre-reduced(600°C,H_(2))catalysts in dehydrogenation of 10HQ also significantly depends on a MgO content and is maximal at Mg:Ni weight ratio 0.056.Using an in-depth study of structure of the original and reduced catalyst samples(Ni-Al_(2)O_(3) and Ni-MgNiOx-Al_(2)O_(3)),it was shown that this regularity is associated with the increased resistance of catalytically active Ni particles to agglomeration during the reductive activation.Also,using the Ni-MgNiOx-Al_(2)O_(3)catalyst for hydrogen storage process(hydrogenation reaction),the possibility of deep quinoline hydrogenation(up to 10HQ)in a flow-type reactor was demonstrated for the first time.展开更多
As the persistent concerns regarding sluggish reaction kinetics and insufficient conductivities of sulfur cathodes in all-solid-state Li-S batteries(ASSLSBs),numerous carbon additives and solid-state electrolytes(SSEs...As the persistent concerns regarding sluggish reaction kinetics and insufficient conductivities of sulfur cathodes in all-solid-state Li-S batteries(ASSLSBs),numerous carbon additives and solid-state electrolytes(SSEs)have been incorporated into the cathode to facilitate ion/electron pathways around sulfur.However,this has resulted in a reduced capacity and decomposition of SSEs.Therefore,it is worth exploring neotype sulfur hosts with electronic/ionic conductivity in the cathode.Herein,we present a hybrid cathode composed of few-layered S/MoS_(2)/C nanosheets(<5 layers)that exhibits high-loading and long-life performance without the need of additional carbon additives in advanced ASSLSBs.The multifunctional MoS_(2)/C host exposes the abundant surface for intimate contacting sites,in situ-formed LixMoS_(2)during discharging as mixed ion/electron conductive network improves the S/Li2S conversion,and contributes extra capacity for the part of active materials.With a high active material content(S+MoS_(2)/C)of 60 wt%in the S/MoS_(2)/C/Li_(6)PS_(5)Cl cathode composite(the carbon content is only~3.97 wt%),the S/MoS_(2)/C electrode delivers excellent electrochemical performance,with a high reversible discharge capacity of 980.3 mAh g^(-1)(588.2 mAh g^(-1)based on the whole cathode weight)after 100 cycles at 100 mA g^(-1).The stable cycling performance is observed over 3500 cycles with a Coulombic efficiency of 98.5%at 600 mA g^(-1),while a high areal capacity of 10.4 mAh cm^(-2)is achieved with active material loading of 12.8 mg cm^(-2).展开更多
Titanium dioxides have been extensively investigated as promising anodes for Lithium ion batteries(LIBs)because of the high–rate capacity and cyclability,as well as the improved safety over graphite anode(1,2)However...Titanium dioxides have been extensively investigated as promising anodes for Lithium ion batteries(LIBs)because of the high–rate capacity and cyclability,as well as the improved safety over graphite anode(1,2)However,as a typical insertion–type anode,anatase TiO2 exhibits low conductivity(10–12S cm-1 for electron conductivity[3]and 10–17–10–10 cm2 s1 for Li+ion diffusion coefficient[4])and poor specific capacity(only accommodate<0.5 Li per bulk TiO2 unit[5]),severely limiting its practical applications.展开更多
Generally speaking, main flow path of gas turbine is assumed to be perfect for standard 3D computation. But in real engine, the turbine annulus geometry is not completely smooth for the presence of the shroud and asso...Generally speaking, main flow path of gas turbine is assumed to be perfect for standard 3D computation. But in real engine, the turbine annulus geometry is not completely smooth for the presence of the shroud and associated cavity near the end wall. Besides, shroud leakage flow is one of the dominant sources of secondary flow in tur- bomachinery, which not only causes a deterioration of useful work but also a penalty on turbine efficiency. It has been found that neglect shroud leakage flow makes the computed velocity profiles and loss distribution signifi- cantly different to those measured. Even so, the influence of shroud leakage flow is seldom taken into considera- tion during the routine of turbine design due to insufficient understanding of its impact on end wall flows and tur- bine performance. In order to evaluate the impact of tip shroud geometry on turbine performance, a 3D computa- tional investigation for 1.5-stage turbine with shrouded blades was performed in this paper. The following ge- ometry parameters were varied respectively：展开更多
Developing large,soft grippers with high omnidirectional load(above 40 kg)has always been challenging.We address this challenge by developing a powerful soft gripper that can grasp the human body based on a soft-enclo...Developing large,soft grippers with high omnidirectional load(above 40 kg)has always been challenging.We address this challenge by developing a powerful soft gripper that can grasp the human body based on a soft-enclosed grasping structure and a soft-rigid coupling structure.The envelope size of the proposed soft gripper is 611.6 mm×559 mm×490.7 mm,the maximum grasping size is 417 mm,and the payload on the human body is more than 90 kg,which has exceeded most existing soft grippers.Furthermore,the grasping force prediction of the gripper is achieved through theoretical modeling.The primary contribution of this work is to overcome the size and payload limits of current soft grippers and implement a human-grasping experiment based on the soft-grasping method.展开更多
Low-temperature fuel cells(LTFCs)are considered to be one of the most promising power sources for widespread application in sustainable and renew-able energy conversion technologies.Although remarkable advances have b...Low-temperature fuel cells(LTFCs)are considered to be one of the most promising power sources for widespread application in sustainable and renew-able energy conversion technologies.Although remarkable advances have been made in the mass activity of catalysts,mass transport impedance needs to be urgently addressed at a well-designed membrane electrode assembly(MEA)scale.Increasing the loading of electrocatalysts is conducive to prepare thinner and more efficient MEAs owing to the resulting enhanced reactant permeability,better proton diffusion,and lower electrical resistance.Herein,recent progress in high-loading(≥40 wt.%)Pt nanoparticle catalysts(NPCs)and high-loading(≥2 wt.%)single-atom catalysts(SACs)for LTFC applications are reviewed.A summary of various synthetic approaches and support materials for high-loading Pt NPCs and SACs is systematically presented.The influences of high surface area and appropriate surface functionalization for Pt NPCs,as well as coordina-tion environment,spatial confinement effect,and strong metal-support interac-tions(SMSI)for SACs are highlighted.Additionally,this review presents some ideas regarding challenges and future opportunities of high-loading catalysts in the application of LTFCs.展开更多
In this paper, a novel engineering platform for throughflow analysis based on streamline curvature approach is developed for the research of a 5-stage compressor. The method includes several types of improved loss and...In this paper, a novel engineering platform for throughflow analysis based on streamline curvature approach is developed for the research of a 5-stage compressor. The method includes several types of improved loss and deviation angle models, which are combined with the authors' adjustments for the purpose of reflecting the influences of three-dimensional internal flow in high-loaded multistage compressors with higher accuracy. In order to validate the reliability and robustness of the method, a series of test cases, including a subsonic compressor P&W 3S1, a transonic rotor NASA Rotor 1B and especially an advanced high pressure core compressor GE E^3 HPC, are conducted. Then the computation procedure is applied to the research of a 5-stage compressor which is designed for developing an industrial gas turbine. The overall performance and aerodynamic configuration predicted by the procedure, both at design- and part-speed conditions, are analyzed and compared with experimental results, which show a good agreement. Further discussion regarding the universality of the method compared with CFD is made afterwards. The throughflow method is verified as a reliable and convenient tool for aerodynamic design and performance prediction of modern high-loaded compressors. This method is also qualified for use in the further optimization of the 5-stage compressor.展开更多
In the traditional design of the centrifugal compressor,the splitter blade and the main blade always keep the same shape.However,to enable high efficiency of the high-loading centrifugal compressor,the matching of des...In the traditional design of the centrifugal compressor,the splitter blade and the main blade always keep the same shape.However,to enable high efficiency of the high-loading centrifugal compressor,the matching of design parameters of the splitter blade and the main blade needs to be optimized.In this paper,the influence of the load distribution between the main blade and the splitter blade on the aerodynamic performance,the flow field,and the internal vortices of a high-loading centrifugal compressor were studied by means of CFD prediction.Four cases with different values of the variable CR which is defined as the load-ratio of splitter blade to main blade were set up.In each case,the splitter blade and the main blade were shaped according to different laws of circulation distribution(_(r)V_(u))while the average circulation of the splitter blade and the main blade at any meridional position were consistent with that of the prototype.The results showed that a proper reduction of the load-ratio of splitter blade to main blade is beneficial to suppress the leakage vortex of the splitter blade and reduce the scale of the wake in the channel near the suction-side of the splitter blade,which consequently improves the flow uniformity at the impeller outlet and enhances the aerodynamic performance of both the stage and the component.The stage isentropic efficiency of the optimal case was found to be 0.7%higher than that of the prototype and the stage total pressure ratio was also improved.The optimal value of CR,which in this investigation is 94%,is supposed to be the result of the trade-off between the development of the wake and the leakage vortices in adjacent two channels.The optimization of the load distribution between the main blade and the splitter blade provides an opportunity to further improve the high-loading centrifugal compressor performance.展开更多
The importance of the oxygen reduction reaction (ORR) in fuel cells and zinc-air batteries is self-evident, and effective catalysts could significantly improve the catalytic efficiency of ORR. Single-atom catalysts ar...The importance of the oxygen reduction reaction (ORR) in fuel cells and zinc-air batteries is self-evident, and effective catalysts could significantly improve the catalytic efficiency of ORR. Single-atom catalysts are gaining increasing interest due to their high atom efficiency and effective catalytic performance compared to other catalyst types. While the optimal loading of catalytic sites in single-atom catalysts significantly influences their catalytic efficiency. However, creating stable single-atom catalysts with high-loading remains a difficult task. Therefore, we showcase and describe the latest developments in techniques for producing single-atom catalysts with high-loadings. In addition, the performance of noble metal, non-precious metal, and diatomic catalysts in ORR processes is summarized. What’s more, the key difficulties and opportunities in the sector are demonstrated by examining the synthesis techniques and evaluating the performance and structure. This review will help researchers to advance the research process of high-loading single-atom catalysts and accelerate their practical application in the field of ORR research.展开更多
Single-atom catalysts(SACs)attract significant attention owing to their high catalytic activity,high metal atom utilization efficiency,and well-defined and configurable active sites.However,achieving single-atom dispe...Single-atom catalysts(SACs)attract significant attention owing to their high catalytic activity,high metal atom utilization efficiency,and well-defined and configurable active sites.However,achieving single-atom dispersion of active metals at high metal loadings remains challenging,limiting the performance of SACs in many practical applications.Herein,we provide a comprehensive review of recent methods developed for synthesizing high-loading SACs,critically exploring their advantages,limitations,and wider applicability.Additionally,we showcase the benefits of high-loading SACs in the oxygen reduction reaction(ORR),water electrolysis,photocatalytic hydrogen production and CO oxidation.Although great recent progress has been made in the synthesis of high loading SACs,simple and universal routes that allowed the preprogrammed preparation of single metal and multi-metal SACs with specific metal coordination need to be discovered.展开更多
基金National Basic Research Program of China (2007CB210100)National Natural Science Foundation of China (50876023)Chinese Specialized Research Fund for the Doctoral Program of Higher Education (20060213007)
文摘This article is aimed to experimentally validate the beneficial effects of boundary layer suction on improving the aerodynamic performance of a compressor cascade with a large camber angle. The flow field of the cascade is measured and the ink-trace flow visualization is also presented. The experimental results show that the boundary layer suction reduces losses near the area of rnidspan in the cascade most effectively for all suction cases under test. Losses of the endwall could remarkably decrease only when the suction is at the position where the boundary layer has separated but still not departed far away from the blade surface. It is evidenced that the higher suction flow rate and the suction position closer to the trailing edge result in greater reduction in losses and the maximum reduction in the total pressure loss accounts to 16.5% for all cases. The suction position plays a greater role in affecting the total pressure loss than the suction flow rate does.
基金co-supported by the National Natural Science Foundation of China(Grants Nos.51576162 and 51536006)
文摘In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex generator with a special configuration and the longitudinal suction slot are adopted. The calculated results show that a reverse flow region, which is considered the main reason for occurring stall at 7.9° incidence, grows and collapses rapidly near the leading edge and leads to two critical points occurring on the end-wall with the increasing incidence in the baseline. As the micro-vortex generator is introduced in the baseline cascade, the corner separation is switched to a trailing edge separation by the thrust from the induced vortex. Meanwhile, the occurrence of failure is delayed due to the mixed low energy fluid and main flow. The synergistic effects between the micro-vortex generator and the boundary layer suction on the performance of the cascade are superior to the baseline at all the incidence conditions before the occurrence of failure, and the sudden deterioration of the cascade occurs at 10.3° incidence. The optimal results show that the farther upstream suction position, the lower total pressure loss of the cascade with vortex generator at the near stall condition. Moreover, the induced vortex with a leg can migrate the accumulated low energy fluid backward to delay the occurrence of stall.
基金financially supported by Beijing Natural Science Foundation(No.2212018)Beijing Institute of Technology Research Fund Program for Young Scholars(No.2022CX01011)+3 种基金Ningbo 3315 Innovative Teams Program(No.2019A-14-C)the National Natural Science Foundation of China(No.12374390)the Member of Youth Innovation Promotion Association Foundation of CAS,China(No.2023310)the Key Scientific and Technological Special Project of Ningbo City No.(2023Z209)。
文摘It is well known that single-atom catalysts(SACs)have become a hot topic in the field of catalysis due to their advantages such as 100%metal atom utilization efficiency,high catalytic activity and selectivity compared with conventional catalysts and nanocatalysts.However,the isolated metal atoms on SACs have thermodynamic instability and tend to agglomerate,which limit their catalytic performance.Therefore,it is of great significance to synthesize stable and high-loading single-atom catalysts(HLSACs).In this paper,we review the research progress of HLSACs from two aspects:design and application.Firstly,we comprehensively introduce the synthesis strategies of HLSACs,namely,top-down and bottom-up methods.Secondly,we overview the application status of HLSACs in three fields:electrocatalysis,thermal catalysis and photocatalysis.Finally,we summarize the development prospects and challenges of HLSACs.
文摘Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loading Fe-SA catalysts by a simple procedure remains challenging.Herein,we report a high-loading(7.5 wt%)Fe-SA/NPC catalyst prepared by carbon-assisted pyrolysis of metal complexes.Both the nitrogen-doped porous carbon(NPC)support with high specific surface area and ο-phenylenediamine(o-PD)play key roles role in the preparation of high-loading Fe-SA/NPC catalysts.The results of X-ray photoelectron spectroscopy,high-angle annular dark-field scanning transmission electron microscopy,and X-ray absorption fine structure spectroscopy experiments show that the Fe atoms are anchored on the carbon carriers in a single-atom site configuration and coordinated with four of the doped nitrogen atoms of the carbon substrates(Fe-N_(4)).The activities of the Fe-SA/NPC catalysts in the oxygen reduction reaction increased with increasing iron loading.The optimized 250Fe-SA/NPC-800 catalyst exhibited an onset potential 0.97 V of and a half-wave potential of 0.85 V.Our study provides a simple approach for the large-scale synthesis of high-loading single-atom catalysts.
基金supported by a grant from the Korea Evaluation Institute of Industrial Technology(KEIT)funded by the Ministry of Trade,Industry and Energy(MOTIE)(No.20012341)。
文摘Sulfur utilization improvement and control of dissolved lithium polysulfide(LiPS;Li_(2)S x,2<x≤8)are cru-cial aspects of the development of lithium-sulfur(Li-S)batteries,especially in high-loading sulfur elec-trodes and low electrolyte/sulfur(E/S)ratios.The sluggish reaction in the low E/S ratio induces poor LiPS solubility and unstable Li_(2)S electrodeposition,resulting in limited sulfur utilization,especially under high-loading sulfur electrode.In this study,we report on salt concentration effects that improve sulfur utilization with a high-loading cathode(6 mgs ulfurcm^(-2)),a high sulfur content(80 wt%)and a low E/S ratio(5 m L gs ulfur^(-1)).On the basis of the rapid LiPS dissolving in a low concentration electrolyte,we estab-lished that the quantity of Li_(2)S electrodeposition from a high Li+diffusion coefficient,referring to the reduction of LiPS precipitation,was significantly enhanced by a faster kinetic.These results demonstrate the importance of kinetic factors for the rate capability and cycle life stability of Li-S battery electrolytes through high Li_(2)S deposition under high-loading sulfur electrode.
基金supported by the Ministry of Science and Higher Education of the Russian Federation within governmental order for Boreskov Institute of Catalysis SB RAS (projects FWUR-2024–0038, FWUR-2024–0032 and FWUR2024–0039)
文摘An effect of Mg introduction on efficiency of high-loaded nickel catalysts in dehydrogenation of decahydroquinoline(10HQ)was inves-tigated.10HQ dehydrogenation is key process for the liquid organic hydrogen carrier(LOHC)storage technology using the quinoline/10HQ pair as H_(2)-lean/H_(2)-rich substrates.An influence of synthesis technique of Ni/Mg/Al catalysts on their properties has been demonstrated.The catalysts were synthesized through coprecipitation of Ni,Mg,Al precursors to obtain layered double hydroxides(LDH)or via syn-thesis of(∼72 wt%)Ni-Al_(2)O_(3) system-also through coprecipitation,followed by modifying with a magnesium-containing precursor.For the catalysts of the first series,the inclusion of magnesium into LDH lattice led to a significant increase in catalytic activity in hydrogen extraction(10HQ dehydrogenation reaction).Despite the decrease in the content of catalytically active nickel,a significant increase in the yield of the dehydrogenation product was observed.This regularity is presumably associated with appearance of basic sites,that accelerates the dehydrogenation reaction.In the case of the second series,activity of pre-reduced(600°C,H_(2))catalysts in dehydrogenation of 10HQ also significantly depends on a MgO content and is maximal at Mg:Ni weight ratio 0.056.Using an in-depth study of structure of the original and reduced catalyst samples(Ni-Al_(2)O_(3) and Ni-MgNiOx-Al_(2)O_(3)),it was shown that this regularity is associated with the increased resistance of catalytically active Ni particles to agglomeration during the reductive activation.Also,using the Ni-MgNiOx-Al_(2)O_(3)catalyst for hydrogen storage process(hydrogenation reaction),the possibility of deep quinoline hydrogenation(up to 10HQ)in a flow-type reactor was demonstrated for the first time.
基金the financial support from the National Natural Science Foundation of China(T2241003)the National Key Research and Development Program of China(2022YFB4003500)the Key R&D project of Hubei Province,China(2021AAA006)
文摘As the persistent concerns regarding sluggish reaction kinetics and insufficient conductivities of sulfur cathodes in all-solid-state Li-S batteries(ASSLSBs),numerous carbon additives and solid-state electrolytes(SSEs)have been incorporated into the cathode to facilitate ion/electron pathways around sulfur.However,this has resulted in a reduced capacity and decomposition of SSEs.Therefore,it is worth exploring neotype sulfur hosts with electronic/ionic conductivity in the cathode.Herein,we present a hybrid cathode composed of few-layered S/MoS_(2)/C nanosheets(<5 layers)that exhibits high-loading and long-life performance without the need of additional carbon additives in advanced ASSLSBs.The multifunctional MoS_(2)/C host exposes the abundant surface for intimate contacting sites,in situ-formed LixMoS_(2)during discharging as mixed ion/electron conductive network improves the S/Li2S conversion,and contributes extra capacity for the part of active materials.With a high active material content(S+MoS_(2)/C)of 60 wt%in the S/MoS_(2)/C/Li_(6)PS_(5)Cl cathode composite(the carbon content is only~3.97 wt%),the S/MoS_(2)/C electrode delivers excellent electrochemical performance,with a high reversible discharge capacity of 980.3 mAh g^(-1)(588.2 mAh g^(-1)based on the whole cathode weight)after 100 cycles at 100 mA g^(-1).The stable cycling performance is observed over 3500 cycles with a Coulombic efficiency of 98.5%at 600 mA g^(-1),while a high areal capacity of 10.4 mAh cm^(-2)is achieved with active material loading of 12.8 mg cm^(-2).
基金supported by the National Natural Science Foundation of China (51772163)the State Key Laboratory of New Ceramic and Fine Processing Tsinghua University (KF201801)
文摘Titanium dioxides have been extensively investigated as promising anodes for Lithium ion batteries(LIBs)because of the high–rate capacity and cyclability,as well as the improved safety over graphite anode(1,2)However,as a typical insertion–type anode,anatase TiO2 exhibits low conductivity(10–12S cm-1 for electron conductivity[3]and 10–17–10–10 cm2 s1 for Li+ion diffusion coefficient[4])and poor specific capacity(only accommodate<0.5 Li per bulk TiO2 unit[5]),severely limiting its practical applications.
基金Financial support from the Innovation Foundation of BUAA for PhD Graduates(YWF-13-A01-014)
文摘Generally speaking, main flow path of gas turbine is assumed to be perfect for standard 3D computation. But in real engine, the turbine annulus geometry is not completely smooth for the presence of the shroud and associated cavity near the end wall. Besides, shroud leakage flow is one of the dominant sources of secondary flow in tur- bomachinery, which not only causes a deterioration of useful work but also a penalty on turbine efficiency. It has been found that neglect shroud leakage flow makes the computed velocity profiles and loss distribution signifi- cantly different to those measured. Even so, the influence of shroud leakage flow is seldom taken into considera- tion during the routine of turbine design due to insufficient understanding of its impact on end wall flows and tur- bine performance. In order to evaluate the impact of tip shroud geometry on turbine performance, a 3D computa- tional investigation for 1.5-stage turbine with shrouded blades was performed in this paper. The following ge- ometry parameters were varied respectively：
基金supported by the National Natural Science Foundation of China (Grant No.51975505)the Ningbo Natural Science Foundation of China (Grant No.2022J134)the Open Research Project of the State Key Laboratory of Industrial Control Technology,Zhejiang University,China (Grant No.ICT 2022B14)。
文摘Developing large,soft grippers with high omnidirectional load(above 40 kg)has always been challenging.We address this challenge by developing a powerful soft gripper that can grasp the human body based on a soft-enclosed grasping structure and a soft-rigid coupling structure.The envelope size of the proposed soft gripper is 611.6 mm×559 mm×490.7 mm,the maximum grasping size is 417 mm,and the payload on the human body is more than 90 kg,which has exceeded most existing soft grippers.Furthermore,the grasping force prediction of the gripper is achieved through theoretical modeling.The primary contribution of this work is to overcome the size and payload limits of current soft grippers and implement a human-grasping experiment based on the soft-grasping method.
基金ThisworkwasfinanciallysupportedbytheHebeiProvince Natural Science Foundation Innovation Group Project(B2021203016)We acknowledge the National Natural Sci-ence Foundation of China(Grant No.52174281,51802059,21905070 and 22075062)+2 种基金China postdoctoral science foun-dation(Grant No.2018M631938)Heilongjiang Postdoc-toral Fund(LBH-Z18066)Heilongjiang Touyan Team(Grant No.HITTY-20190033).
文摘Low-temperature fuel cells(LTFCs)are considered to be one of the most promising power sources for widespread application in sustainable and renew-able energy conversion technologies.Although remarkable advances have been made in the mass activity of catalysts,mass transport impedance needs to be urgently addressed at a well-designed membrane electrode assembly(MEA)scale.Increasing the loading of electrocatalysts is conducive to prepare thinner and more efficient MEAs owing to the resulting enhanced reactant permeability,better proton diffusion,and lower electrical resistance.Herein,recent progress in high-loading(≥40 wt.%)Pt nanoparticle catalysts(NPCs)and high-loading(≥2 wt.%)single-atom catalysts(SACs)for LTFC applications are reviewed.A summary of various synthetic approaches and support materials for high-loading Pt NPCs and SACs is systematically presented.The influences of high surface area and appropriate surface functionalization for Pt NPCs,as well as coordina-tion environment,spatial confinement effect,and strong metal-support interac-tions(SMSI)for SACs are highlighted.Additionally,this review presents some ideas regarding challenges and future opportunities of high-loading catalysts in the application of LTFCs.
基金supported by SEDRIand the National Natural Science Foundation of China(Grant No.51136003)
文摘In this paper, a novel engineering platform for throughflow analysis based on streamline curvature approach is developed for the research of a 5-stage compressor. The method includes several types of improved loss and deviation angle models, which are combined with the authors' adjustments for the purpose of reflecting the influences of three-dimensional internal flow in high-loaded multistage compressors with higher accuracy. In order to validate the reliability and robustness of the method, a series of test cases, including a subsonic compressor P&W 3S1, a transonic rotor NASA Rotor 1B and especially an advanced high pressure core compressor GE E^3 HPC, are conducted. Then the computation procedure is applied to the research of a 5-stage compressor which is designed for developing an industrial gas turbine. The overall performance and aerodynamic configuration predicted by the procedure, both at design- and part-speed conditions, are analyzed and compared with experimental results, which show a good agreement. Further discussion regarding the universality of the method compared with CFD is made afterwards. The throughflow method is verified as a reliable and convenient tool for aerodynamic design and performance prediction of modern high-loaded compressors. This method is also qualified for use in the further optimization of the 5-stage compressor.
基金financially supported by NationalScience and Technology Major Project(Grant No.2017-Ⅰ-0005-0006 and Grant No.2019-Ⅱ-0020-0041)。
文摘In the traditional design of the centrifugal compressor,the splitter blade and the main blade always keep the same shape.However,to enable high efficiency of the high-loading centrifugal compressor,the matching of design parameters of the splitter blade and the main blade needs to be optimized.In this paper,the influence of the load distribution between the main blade and the splitter blade on the aerodynamic performance,the flow field,and the internal vortices of a high-loading centrifugal compressor were studied by means of CFD prediction.Four cases with different values of the variable CR which is defined as the load-ratio of splitter blade to main blade were set up.In each case,the splitter blade and the main blade were shaped according to different laws of circulation distribution(_(r)V_(u))while the average circulation of the splitter blade and the main blade at any meridional position were consistent with that of the prototype.The results showed that a proper reduction of the load-ratio of splitter blade to main blade is beneficial to suppress the leakage vortex of the splitter blade and reduce the scale of the wake in the channel near the suction-side of the splitter blade,which consequently improves the flow uniformity at the impeller outlet and enhances the aerodynamic performance of both the stage and the component.The stage isentropic efficiency of the optimal case was found to be 0.7%higher than that of the prototype and the stage total pressure ratio was also improved.The optimal value of CR,which in this investigation is 94%,is supposed to be the result of the trade-off between the development of the wake and the leakage vortices in adjacent two channels.The optimization of the load distribution between the main blade and the splitter blade provides an opportunity to further improve the high-loading centrifugal compressor performance.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2021QB150)Research Program of Qilu Institute of Technology(Nos.QIT23TP019,QIT23TP010,and QIT22NK005).
文摘The importance of the oxygen reduction reaction (ORR) in fuel cells and zinc-air batteries is self-evident, and effective catalysts could significantly improve the catalytic efficiency of ORR. Single-atom catalysts are gaining increasing interest due to their high atom efficiency and effective catalytic performance compared to other catalyst types. While the optimal loading of catalytic sites in single-atom catalysts significantly influences their catalytic efficiency. However, creating stable single-atom catalysts with high-loading remains a difficult task. Therefore, we showcase and describe the latest developments in techniques for producing single-atom catalysts with high-loadings. In addition, the performance of noble metal, non-precious metal, and diatomic catalysts in ORR processes is summarized. What’s more, the key difficulties and opportunities in the sector are demonstrated by examining the synthesis techniques and evaluating the performance and structure. This review will help researchers to advance the research process of high-loading single-atom catalysts and accelerate their practical application in the field of ORR research.
基金The work was supported by the National Natural Science Foundation of China(No.92061125,22209186)Beijing Natural Science Foundation(No.Z200012)+1 种基金Jiangxi Natural Science Foundation(No.20212ACB213009,20223BBG74004)Youth Innovation Promotion Association,CAS(No.2023343)。
文摘Single-atom catalysts(SACs)attract significant attention owing to their high catalytic activity,high metal atom utilization efficiency,and well-defined and configurable active sites.However,achieving single-atom dispersion of active metals at high metal loadings remains challenging,limiting the performance of SACs in many practical applications.Herein,we provide a comprehensive review of recent methods developed for synthesizing high-loading SACs,critically exploring their advantages,limitations,and wider applicability.Additionally,we showcase the benefits of high-loading SACs in the oxygen reduction reaction(ORR),water electrolysis,photocatalytic hydrogen production and CO oxidation.Although great recent progress has been made in the synthesis of high loading SACs,simple and universal routes that allowed the preprogrammed preparation of single metal and multi-metal SACs with specific metal coordination need to be discovered.
