以一台50 k W永磁驱动电机为例,根据流体力学和传热学原理,利用有限体积法对电机温度场进行了研究,分析出其温度分布规律。该结果与实验所获数据相吻合,证实了计算方法和计算结果的合理性。但是为了有效地解决由于接线盒所在区域温升过...以一台50 k W永磁驱动电机为例,根据流体力学和传热学原理,利用有限体积法对电机温度场进行了研究,分析出其温度分布规律。该结果与实验所获数据相吻合,证实了计算方法和计算结果的合理性。但是为了有效地解决由于接线盒所在区域温升过高,温度梯度较大的问题,提出4种对接线盒结构的优化方案,对其不同方案下电机整体温度分布及接线盒所对应的电机内部径向区域温度场特性进行了详细地分析,所得结论为永磁驱动电机结构的优化设计提供了理论参考。展开更多
The development of highly efficient and stable Pd-based catalysts is crucial to improve their sluggish oxygen reduction reaction(ORR)kinetics in acid media.To improve ORR activity and utilization efficiency of Pd,an i...The development of highly efficient and stable Pd-based catalysts is crucial to improve their sluggish oxygen reduction reaction(ORR)kinetics in acid media.To improve ORR activity and utilization efficiency of Pd,an ideal catalyst should have ORR-favorable chemical environment,optimized geometric structure,and long periods of operation.In this work,we first synthesize a novel trimetallic Au@PdPb core–shell catalyst consisting of PdPb alloy nano-layers grown on the surface of ultrathin Au nanowires(NWs)by a two-step water-bath method.The Au@PdPb NWs have the merits of anisotropic one-dimensional nanostructure,high utilization efficiency of Pd atoms and doping of Pb atoms.Because of the structural and multiple compositional advantages,Au@PdPb NWs exhibit remarkably enhanced ORR activity with a high haIf-wave potential(0.827 V),much better than those of commercial Pd black(0.788 V)and bimetallic Au@Pd NWs(0.803 V).Moreover,Au@PdPb NWs display better electrocatalytic stability for the ORR than those of Pd black and Au@Pd NWs.This study demonstrates the validity of our approach for deriving highly ORR-active Pd-based catalysts by modifying their structure and composition.展开更多
Ultrathin Pd nanosheets(NSs)have great advantages in catalysis due to their large specific surface area and high percentage of under-coordinated atoms.However,the electrochemical performance still can be improved via ...Ultrathin Pd nanosheets(NSs)have great advantages in catalysis due to their large specific surface area and high percentage of under-coordinated atoms.However,the electrochemical performance still can be improved via composition-controllable growth of their solid solution.Herein,seeded alloying strategy was proposed to synthesize Pd-Cu solid solution from Pd NSs and Pd-Cu nanostructures with tunable molar ratios obtained by changing the amount of Cu precursor.As compared to the pristine Pd NSs,the Pd-Cu solid solution shows significantly enhanced methanol oxidation reaction(MOR)performance over those of Pd NSs and homemade Pd/C as the incorporation of Cu weakens the adsorption of CO intermediate on Pd in the MOR process.The choice of template is pivotal to the growth,as a shape-dependent behavior could be identified in the alloying of Cu with Pd nanosheets enclosed by{111}and{100}facets,Pd nanocubes enclosed by{100}facet,and Pd nano-tetrahedrons enclosed by{111}facet.The Pd-Cu solid solution with tunable composition can only be obtained from Pd NSs and the shape-dependent alloying process is mainly determined by the diffusion barrier and the minimum diffusion depth of the different facets.展开更多
文摘以一台50 k W永磁驱动电机为例,根据流体力学和传热学原理,利用有限体积法对电机温度场进行了研究,分析出其温度分布规律。该结果与实验所获数据相吻合,证实了计算方法和计算结果的合理性。但是为了有效地解决由于接线盒所在区域温升过高,温度梯度较大的问题,提出4种对接线盒结构的优化方案,对其不同方案下电机整体温度分布及接线盒所对应的电机内部径向区域温度场特性进行了详细地分析,所得结论为永磁驱动电机结构的优化设计提供了理论参考。
基金supported by the Academic Research Fund(AcRF)Tier 1 Grant(No.RG105/19)from the Ministry of Education in Singapore,the National Natural Science Foundation of China(No.21875112)and the China Scholarship Council(No.201906090199).
文摘The development of highly efficient and stable Pd-based catalysts is crucial to improve their sluggish oxygen reduction reaction(ORR)kinetics in acid media.To improve ORR activity and utilization efficiency of Pd,an ideal catalyst should have ORR-favorable chemical environment,optimized geometric structure,and long periods of operation.In this work,we first synthesize a novel trimetallic Au@PdPb core–shell catalyst consisting of PdPb alloy nano-layers grown on the surface of ultrathin Au nanowires(NWs)by a two-step water-bath method.The Au@PdPb NWs have the merits of anisotropic one-dimensional nanostructure,high utilization efficiency of Pd atoms and doping of Pb atoms.Because of the structural and multiple compositional advantages,Au@PdPb NWs exhibit remarkably enhanced ORR activity with a high haIf-wave potential(0.827 V),much better than those of commercial Pd black(0.788 V)and bimetallic Au@Pd NWs(0.803 V).Moreover,Au@PdPb NWs display better electrocatalytic stability for the ORR than those of Pd black and Au@Pd NWs.This study demonstrates the validity of our approach for deriving highly ORR-active Pd-based catalysts by modifying their structure and composition.
基金This work was accomplished under the support of National Natural Science Foundation of Tianjin,China(No.22175127)Institute of Energy,Hefei Comprehensive National Science Center(No.19KZS207).
文摘Ultrathin Pd nanosheets(NSs)have great advantages in catalysis due to their large specific surface area and high percentage of under-coordinated atoms.However,the electrochemical performance still can be improved via composition-controllable growth of their solid solution.Herein,seeded alloying strategy was proposed to synthesize Pd-Cu solid solution from Pd NSs and Pd-Cu nanostructures with tunable molar ratios obtained by changing the amount of Cu precursor.As compared to the pristine Pd NSs,the Pd-Cu solid solution shows significantly enhanced methanol oxidation reaction(MOR)performance over those of Pd NSs and homemade Pd/C as the incorporation of Cu weakens the adsorption of CO intermediate on Pd in the MOR process.The choice of template is pivotal to the growth,as a shape-dependent behavior could be identified in the alloying of Cu with Pd nanosheets enclosed by{111}and{100}facets,Pd nanocubes enclosed by{100}facet,and Pd nano-tetrahedrons enclosed by{111}facet.The Pd-Cu solid solution with tunable composition can only be obtained from Pd NSs and the shape-dependent alloying process is mainly determined by the diffusion barrier and the minimum diffusion depth of the different facets.
