A new analysis of two phase flow on hydrogen production from water electrolysis

It is clear that the entire world have to research, develop, demonstrate and plan for alternative energy systems for shorter term and also longer term. As a clean energy carrier, hydrogen has become increasingly important. It owes its prestige to the increase within the energy costs as a result of the equivocalness in the future availability. Two phase flow and hydrogen gas flow dynamics effect on performance of water electrolysis. Hydrogen bubbles are recognized to influence energy and mass transfer in gas-evolving electrodes. The movement of hydrogen bubbles on the electrodes in alkaline electrolysis is known to affect the reaction efficiency. Within the scope of this research, a physical modeling for the alkaline electrolysis is determined and the studies about the two-phase flow model are carried out for this model. Internal and external forces acting on the resulting bubbles are also determined. In this research, the analytical solution of two-phase flow analysis of hydrogen in the electrolysis is analyzed.     

Green preparation of vanadium carbide through one-step molten salt electrolysis

Vanadium carbide (VC) as excellent ceramic and functional material is usually prepared by carbothermal reduction of V₂O₅ which must be extracted from a typical V slag by complex processes. Pollutants, such as ammonia-nitrogen wastewater, NH₃ and CO₂ are inevitably discharged. A novel and green method for VC preparation was proposed by one-step co-electrolysis of soluble NaVO₃ and CO₂ in molten salt. It was found that VC with high purity was easily obtained by reducing electrolysis temperature and CO₂ flow rate to 600 °C and 10 mL min⁻¹ at 3.0 V. Besides VC with particles and layered stacking structure in products, a small amount of carbon and oxygen elements existed. The atomic percentage contents of C, V, and O elements in VC were about 50.0%, 44.5% and 3.8%, respectively. During electrolysis, CO₃²⁻ and VO₃⁻ was reduced at about −0.55 V (vs. Ag/AgCl) and −1.38 V (vs. Ag/AgCl), respectively. CO₃²⁻ ions were more easily reduced than VO₃⁻, and was firstly reduced to CO₂²⁻ and then converted to C. Then, VC was prepared by two routes from CO₂ and NaVO₃. One route is that VO₃⁻ ions are firstly electroreduced to VO₂⁻ ions and then are further electroreduced to VC with C. Another route is that VO₃⁻ ions are electroreduced to V which in-situ reacted with C to VC. Both VO₃⁻ and CO₃²⁻ ions are electroreduced by two-step process. In final, VC is in-situ deposited on cathode. It provides a novel and green way to prepare VC and also achieves the high value-added utilization of vanadium slag and CO₂.     

Hydrogen supply scenarios for a climate neutral energy system in Germany

A climate neutral energy system in Germany will most likely require green hydrogen. Two important factors, that determine whether the hydrogen will be imported or produced locally from renewable energy are still uncertain though - the import price for green hydrogen and the upper limit for photovoltaic installations. To investigate the impact of these two factors, the authors calculate cost optimized climate neutral energy systems while varying the import price from 1.25 €/kg to 5 €/kg with unlimited import volume and the photovoltaic limit from 300 GW to unlimited. In all scenarios, hydrogen plays a significant role. At a medium import price of 3.75 €/kg and photovoltaic limits of 300–900 GW the hydrogen supply is around 1200 to 1300 TWh with import shares varying from 60 to 85%. In most scenarios the electrolysis profile is highly correlated with the photovoltaic power, which leads to full load hours of 1870 h–2770 h.     

有色冶金中的离子交换膜电解技术

离子膜电解技术在有色冶金工业中有重要的应用价值 ,膜的选择透过性和不同的电极过程相结合可完成各种冶金过程。综述了离子交换膜电解技术在高纯金属的制备、无机物的电化合成、多价离子氧化状态的控制及金属离子的分离等冶金领域的研究现状 ,分析了该技术的特点 ,并指出了该技术要实现工业化必须解决的主要问题     

Highly stable novel inorganic hydrides from aqueous electrolysis and plasma electrolysis

After 10⁴ h of continuous aqueous electrolysis with K₂CO₃ as the electrolyte, highly stable novel inorganic hydride compounds such as KH KHCO₃ and KH were isolated and identified by time of flight secondary ion mass spectroscopy (ToF-SIMS). The existence of novel hydride ions was determined using X-ray photoelectron spectroscopy (XPS) and solid state magic-angle spinning proton nuclear magnetic resonance spectroscopy (¹H MAS NMR). A novel hydride ion formed by plasma electrolysis of a K₂CO₃, Rb₂CO₃, or Cs₂CO₃ electrolyte was also observed by high resolution visible spectroscopy at 407.0 nm corresponding to its predicted binding energy of 3.05 eV.     

Effects of temperature and current density on the surface hardness and tribological properties of Ti-6Al-4V alloy by molten salt carburization

Surface hardening of Ti-6Al-4V alloy was achieved by carburization in a molten salt bath containing BaCO₃ as the carbon-yielding agent with electrolysis within the temperature range 790–930°C. The hardness of the total carburizing layer (TCD) is influenced by the bath temperature, the applied current density and the carburizing period. The major hardening effect is considered to be the formation of a solid solution of carbon in -Ti. The oxide film wrapping at the outermost surface of cathodically charged specimens, identified to be mainly BaTiO₃, was formed irrespective of the bath temperature during the quenching process and has no effect on the surface hardening. The optimal carburizing parameters obtained in this study for surface hardening are carburizing at 930±10°C (bath temperature) and 0.3 A/Cm² (applied current density) for 90 min (carburizing period), while those for tribological properties improvement are carburizing at 860±5°C and 0.3 A/Cm² for 90 min.     

金属材料电解液体磨料冲刷复合抛光工艺

工件在电镀前抛光是一道费工费时的工序，我们利用电解、液体磨料冲刷复合抛光工艺，可及时去除电解过程中在工作表面产生的钝化膜，提高电解抛光质量和速度，降低劳动强度，此工艺特别适用于批量较大、表面形状较复杂的零件的抛光。     

关于阜康铜渣冶炼工艺的研究和选择

我国独立开发的镍精炼新工艺已在新疆实际应用。经阜康冶炼厂选择性浸出提取后,金属化高冰镍原料中大量铜及贵金属进入了铜渣。在完成了阜康铜渣吹炼粗铜的试验研究任务之后,北京矿冶研究总院又制订了铜渣"焙烧—浸出—电解"方案,并进行了验证试验。证实了该工艺具有铜回收率高、浸出液较为纯净可直接电解、镍能综合回收、浸出渣率低和贵金属富集比高等特点。结合公司和阜康实际,最终推荐了焙烧、浸出方案。该方案已被新疆有关部门采纳,于1999年建成了国内能力最大的采用溶液电积工艺生产电解铜的车间(5000t电解铜/a),投产后经济效益显著。     

半氧化锰矿制取电解金属锰初探

以中部半氧化矿为原料,进行制取电解金属锰的试验,初步探索其对电解金属锰生产的影响程度,查找引起不正常的原因因素,探索工艺参数,对局部工艺参数调整并指导生产。