The as-prepared Ti-Zr hydride powder is used as dopant to improve hydrogen storage properties of NaAlH4 upon mechanical milling under argon atmosphere. The as-milled sample is investigated by X-ray diffraction(XRD),sc...The as-prepared Ti-Zr hydride powder is used as dopant to improve hydrogen storage properties of NaAlH4 upon mechanical milling under argon atmosphere. The as-milled sample is investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM) and Sievert's technology test. It is observed that Ti-Zr hydride doped NaAlH4 discharges 2.7% and 4.0%(mass fraction) of hydrogen in 40 min and 11 h at 160 ℃,respectively,and keeps its reversible dehydrogenation capacity at 4.0%(mass fraction) after 10 hydrogenation/dehydrogenation cycles. These results show the Ti-Zr hydride doped NaAlH4 has good reversible hydrogen storage capacity and kinetics. XRD and SEM investigations also show that the doped Ti-Zr hydride uniformly distributes in NaAlH4 substrate and keeps stable during the hydrogenation/dehydrogenation cycle,indicating that Ti-Zr hydride plays the main surface-catalytic role on improving reversible hydrogen storage properties of NaAlH4.展开更多
层间距以及管间距不仅影响换热器的传热性能,而且影响换热器的几何结构。本文采用FloEFD软件数值模拟研究了三种不同层间距(4 mm, 7 mm, 10 mm)以及管间距(15 mm, 18 mm, 21 mm)对缠绕管换热器的换热性能的影响。结果表明在不同层间距...层间距以及管间距不仅影响换热器的传热性能,而且影响换热器的几何结构。本文采用FloEFD软件数值模拟研究了三种不同层间距(4 mm, 7 mm, 10 mm)以及管间距(15 mm, 18 mm, 21 mm)对缠绕管换热器的换热性能的影响。结果表明在不同层间距条件下壳程流体出口温度、壳程流体速度以及壳程压降随着层间距的增加而减小;在不同管间距条件下壳程流体出口温度、壳程流体速度随着管间距的增加而减小而壳程压降随着层间距的增加而增大;采用换热器综合性能评价指标(单位壳程压降)来衡量换热器的传热效果,表明层间距以及管间距越小,换热器综合性能指标最好。研究结果对换热器的设计具有一定的指导意义。展开更多
基金Projects(2006AA05Z131 2006AA05Z144) supported by the National High-Tech Research and Development Program of China
文摘The as-prepared Ti-Zr hydride powder is used as dopant to improve hydrogen storage properties of NaAlH4 upon mechanical milling under argon atmosphere. The as-milled sample is investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM) and Sievert's technology test. It is observed that Ti-Zr hydride doped NaAlH4 discharges 2.7% and 4.0%(mass fraction) of hydrogen in 40 min and 11 h at 160 ℃,respectively,and keeps its reversible dehydrogenation capacity at 4.0%(mass fraction) after 10 hydrogenation/dehydrogenation cycles. These results show the Ti-Zr hydride doped NaAlH4 has good reversible hydrogen storage capacity and kinetics. XRD and SEM investigations also show that the doped Ti-Zr hydride uniformly distributes in NaAlH4 substrate and keeps stable during the hydrogenation/dehydrogenation cycle,indicating that Ti-Zr hydride plays the main surface-catalytic role on improving reversible hydrogen storage properties of NaAlH4.
文摘层间距以及管间距不仅影响换热器的传热性能,而且影响换热器的几何结构。本文采用FloEFD软件数值模拟研究了三种不同层间距(4 mm, 7 mm, 10 mm)以及管间距(15 mm, 18 mm, 21 mm)对缠绕管换热器的换热性能的影响。结果表明在不同层间距条件下壳程流体出口温度、壳程流体速度以及壳程压降随着层间距的增加而减小;在不同管间距条件下壳程流体出口温度、壳程流体速度随着管间距的增加而减小而壳程压降随着层间距的增加而增大;采用换热器综合性能评价指标(单位壳程压降)来衡量换热器的传热效果,表明层间距以及管间距越小,换热器综合性能指标最好。研究结果对换热器的设计具有一定的指导意义。
