Design Optimization of a Self-circulated Hydrogen Cooling System for a PM Wind Generator Based on Taguchi Method

With the continuous improvement of permanent magnet(PM)wind generators'capacity and power density,the design of reasonable and efficient cooling structures has become a focus.This paper proposes a fully enclosed self-circulating hydrogen cooling structure for a originally forced-air-cooled direct-drive PM wind generator.The proposed hydrogen cooling system uses the rotor panel supports that hold the rotor core as the radial blades,and the hydrogen flow is driven by the rotating plates to flow through the axial and radial vents to realize the efficient cooling of the generator.According to the structural parameters of the cooling system,the Taguchi method is used to decouple the structural variables.The influence of the size of each cooling structure on the heat dissipation characteristic is analyzed,and the appropriate cooling structure scheme is determined.

Optimization of the Gas Generator in Composite Power System with Tip-Jet Rotor

The key and bottleneck of research on the tip-jet rotor compound helicopter lies in the power system. Computational Fluid Dynamics (CFD) was used to numerically simulate the gas generator and rotor inner passage of the tip-jet rotor composite power system, studying the effects of intake mode, inner cavity structure, propellant components, and injection amount on the characteristics of the composite power system. The results show that when a single high-temperature exhaust gas enters, the gas generator outlet fluid is uneven and asymmetric;when two-way high-temperature exhaust gas enters, the outlet temperature of the gas generator with a tilted inlet is more uniform than that with a vertical inlet;adding an inner cavity improves the temperature and velocity distribution of the gas generator's internal flow field;increasing the energy of the propellant is beneficial for improving the available moment.

Hydrogen generation from polyvinyl alcohol-contaminated wastewater by a process of supercritical water gasification

Gasification of polyvinyl alcohol （PVA）-contaminated wastewater in supercritical water （SCW） was investigated in a continuous flow reactor at 723-873 K, 20-36 MPa and residence time of 20-450 s. The gas and liquid products were analyzed by GC/TCD, and TOC analyzer. The main gas products were H2, CH4, CO and CO2. Pressure change had no significant influence on gasification efficiency. Higher temperature and longer residence time enhanced gasification efficiency, and lower temperature favored the production of H2. The effects of KOH catalyst on gas product composition were studied, and gasification efficiency were analyzed. The TOC removal efficiency （RTOC）, carbon gasification ratio （RCG） and hydrogen gasification ratio （RHG） were up to 96.00%, 95.92% and 126.40% at 873 K and 60 s, respectively, which suggests PVA can be completely gasified in SCW. The results indicate supercritical water gasification for hydrogen generation is a promising process for the treatment ofPVA wastewater.

Hydrogen generation from methanolysis of sodium borohydride over Co/Al_2O_3 catalyst

Co/Al2O3 catalyst is prepared with an impregnation-chemical reduction method and used to catalyze the methanolysis of sodium borohydride （NaBH 4） for hydrogen generation.At solution temperature of 0 C,the methanolysis reaction can be effectively accelerated using Co/Al2O3 catalyst and provide a desirable hydrogen generation rate,which makes it suitable for applications under the circumstance of low environmental temperature.The byproduct of methanolysis reaction is analyzed by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FTIR）.The characterization results indicate that methanol can be easily recovered after methanolysis reaction by hydrolysis of the methanolysis byproduct,NaB（OCH 3） 4.The catalytic activity of Co/Al2O3 towards NaBH 4 methanolysis can be further improved by appropriate calcination treatment.The catalytic methanolysis kinetics and catalyst reusability are also studied over the Co/Al2O3 catalyst calcined at the optimized temperature.

Polyoxometalates-engineered hydrogen generation rate and durability of Pt/CNT catalysts from ammonia borane

Heterogeneously catalyzed hydrolytic dehydrogenation of ammonia borane is a remarkable structure sensitive reaction. In this work, a strategy by using polyoxometalates(POMs) as the ligands is proposed to engineer the surface and electronic properties of Pt/CNT catalysts toward the enhanced hydrogen generation rate and durability. Three kinds of POMs, i.e., silicotungstic acid(STA), phosphotungstic acid(PTA)and molybdophosphoric acid(PMA), are comparatively studied, among which the STA shows positive effects on the catalytic activity and durability. A catalyst structure-performance relationship is established by a combination of kinetic and isotopic analyses with multiple characterization techniques, such as HAADF-STEM, EDS, Raman spectroscopy and XPS. It is shown that the STA compared to the other two POMs can increase the Pt binding energy and thus promote the reaction. The insights demonstrated here could open a new avenue for boosting the reaction by employing the POMs as the ligands to engineer the catalyst electronic properties.

Hydrogen generation via hydrolysis of nanocrystalline MgH_2 and MgH_2-based composites

Nanocrystalline MgH2 and MgH2-based composites with 25%（mass fraction） of Al, Ca, or CaH2 as an individual additive respectively were prepared by ball milling. The crystallite size and morphology of the as-milled powders were characterized and their hydrolysis behaviours were investigated in comparison with commercial polycrystalline MgH2. The results show that the crystallite size of both MgH2 and MgH2-based composites is reduced to less than 13nm after milling for 15h. Due to its enhanced specific surface area and unique nanocrystalline structure, the as-milled MgH2 shows much better hydrolysis kinetics than the commercial polycrystalline MgH2, with the hydrolysed fraction upon hydrolysing for 70min enhances from 7.5% to about 25%. As compared with the as-milled MgH2, the MgH2-based composites with either CaH2 or Ca as an additive present further greatly improved hydrolysis kinetics, with the hydrolysed fraction for 80min achieving about 76% and 62% respectively. However, the addition of Al doesn’t show any positive effect on the improvement of the hydrolysis kinetics of MgH2.

Mesoporous cadmium bismuth niobate(CdBi2Nb2O9)nanospheres for hydrogen generation under visible light

Herein, we report visible light active mesoporous cadmium bismuth niobate（CBN） nanospheres as a photocatalyst for hydrogen（H） generation from copious hydrogen sulfide（HS）. CBN has been synthesized by solid state reaction（SSR） and also using combustion method（CM） at relatively lower temperatures.The as-synthesized materials were characterized using different techniques. X-ray diffraction analysis shows the formation of single phase orthorhombic CBN. Field emission scanning electron microscopy and high resolution-transmission electron microscopy showed the particle size in the range of.5–1 μm for CBN obtained by SSR and 50–70 nm size nanospheres using CM, respectively. Interestingly, nanospheres of size 50–70 nm self assembled with 5–7 nm nanoparticles were observed in case of CBN prepared by CM.The optical properties were studied using UV–visible diffuse reflectance spectroscopy and showed band gap around.0 eV for SSR and 3.1 eV for CM. The slight shift in band gap of CM is due to nanocrystalline nature of material. Considering the band gap in visible region, the photocatalytic activity of CBN for hydrogen production from HS has been performed under visible light. CBN prepared by CM has shown utmost hydrogen evolution i.e. 6912 μmol/h/0.5 g which is much higher than CBN prepared using SSR.The enhanced photocatalytic property can be attributed to the smaller particle size, crystalline nature,high surface area and mesoporous structure of CBN prepared by combustion method. The catalyst was found to be stable, active and can be utilized for water splitting.

Effects of Aluminum Particle Size, Galinstan Content and Reaction Temperature on Hydrogen Generation Rate Using Activated Aluminum and Water

Aluminum, in its normal passive oxidized state, does not react with water. In this work, aluminum activation is carried out using liquid metal eutectics Ga-In-Sn-Zn (60:25:10:5). Subsequently, the reaction with water of activated aluminum to produce hydrogen has been examined. The effects of aluminum particle size, liquid eutectics content, and reaction temperature on hydrogen production rates are investigated. The liquid eutectics interaction with aluminum is discussed and the mechanisms of liquid eutectics penetration within the Al particles have been investigated. The specific surface area of the Al particles, the mass ratio of Al to eutectics content and the reaction temperature were found to determine the hydrogen production rate and yield. It is observed that micro-aluminum particles of ~30 μm size display lower reaction rates and hydrogen yields than ~350 μm size particles.

Integrated Ni-P-S nanosheets array as superior electrocatalysts for hydrogen generation

Searching for efficient and robust non-noble electrocatalysts for hydrogen generation is extremely desirable for future green energy systems.Here, we present the synthesis of integrated Ni-P-S nanosheets array including Ni_2P and NiS on nickel foam by a simple simultaneous phosphorization and sulfurization strategy. The resultant sample with optimal composition exhibits superior electrocatalytic performance for hydrogen evolution reaction(HER) in a wide pH range. In alkaline media, it can generate current densities of 10, 20 and 100 mA cm^(-2) at low overpotentials of only-101.9,-142.0 and-207.8 mV with robust durability. It still exhibits high electrocatalytic activities even in acid or neutral media. Such superior electrocatalytic performances can be mainly attributed to the synergistic enhancement of the hybrid Ni-P-S nanosheets array with integration microstructure. The kind of catalyst gives a new insight on achieving efficient and robust hydrogen generation.

Low-order harmonic generation of hydrogen molecular ion in laser field studied by the two-state model

The low-order harmonic generation of hydrogen molecular ion interacting with a linearly polarized laser field has been investigated theoretically by using a simple two-state model. The validity of the two-state model is carefully examined by comparing the harmonic spectra of hydrogen molecular ion obtained from this model with those from the three-dimensional time-dependent Schr¨odinger equation. When combined with the Morlet transform of quantum time-frequency spectrum,the two-state model can be used to study the dynamical origin of the low-order harmonic generation of hydrogen molecular ion driven by low-frequency pulses. In addition, some interesting structures of the time profiles for low order harmonics are obtained.

Effect of doped Ni-Bi-B alloy on hydrogen generation performance of Al-InCl3

In this work,Ni-Bi-B alloy has been synthesized via chemical synthesis method.A new kind of Al-InCl3-(Ni-Bi-B)composite has been prepared by high energy mechanical ball grinding A1 powder with additives.Results show that the doped Ni-Bi-B alloy can significantly improve the hydrogen generation performance of Al-InCl3 and the catalytic activity is enhanced with the increasing content of Bi in Ni-Bi-B alloy.Under optimal conditions,the hydrogen generation yield and conversion yield of Al-InCl3-(Ni-Bi-B)reached1196.8 mL g^-1 and 100.0%at room temperature,respectively.Mechanism study shows five kinds of active sites,such as the fresh surface/defect of Al particle,Al-AlCl3,Al-In,Al-Bi/B and Al-Ni/B produced during the ball milling process.Their synergistic effect enhances the hydrogen generation performance of AlInCl3-(Ni-Bi-B)remarkably.In general,the proposed Al-InCl3-(Ni-Bi-B)composite is possible to serve as hydrogen generation material for fuel cells.

Thermodynamic Aspects of the Graphene/Graphane/Hydrogen Systems: Relevance to the Hydrogen On-Board Storage Problem

The present analytical review is devoted to the current problem of thermodynamic stability and related thermodynamic characteristics of the following graphene layers systems: 1) double-side hydrogenated graphene of composition CH (theoretical graphane) (Sofo et al. 2007) and experimental graphane (Elias et al. 2009);2) theoretical single-side hydrogenated graphene of composition CH;3) theoretical single-side hydrogenated graphene of composition C2H (graphone);4) experimental hydrogenated epitaxial graphene, bilayer graphene and a few layers of graphene on SiO2 or other substrates;5) experimental and theoretical single-external side hydrogenated single-walled carbon nanotubes, and experimental hydrofullerene C60H36;6) experimental single-internal side hydrogenated (up to C2H or CH composition) graphene nanoblisters with intercalated high pressure H2 gas inside them, formed on a surface of highly oriented pyrolytic graphite or epitaxial graphene under the atomic hydrogen treatment;and 7) experimental hydrogenated graphite nanofibers-multigraphene with intercalated solid H2 nano-regions of high density inside them, relevant to solving the problem of hydrogen on-board storage (Nechaev 2011-2012).

General calculation formulas and recurrence relations of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0

In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.

Comparing of Hydrogen On-Board Storage by the Largest Car Companies, Relevance to Prospects for More Efficient Technologies

It presented a comparative consideration of General Motors long-term activities on the current subject of fuel-cell-powered electric vehicles vs Toyota Mirai recent results, relevant to prospects on more efficient and safe technologies of the hydrogen on-board storage. It also presented a call on the project International cooperation. The main aim of this paper is to attract attention of General Motors, Toyota and/or other large car companies to a real possibility of developing and using, in the nearest future, of the break-through hydrogen on-board storage technology based on the solid H2 intercalation into graphite nanostructures.

Enhancement in solar hydrogen generation efficiency using InGaN photoelectrode after surface roughening treatment with nano-sized Ni mask

A significant enhancement in solar hydrogen generation efficiency has been achieved by inductive coupled etching （ICP） surface roughening treatment using nano-sized nickel mask. As much as 7 times improvement of photocurrent is demonstrated in comparison with a planar one fabricated from the same parent wafer. Under identical illumination conditions in HBr solution, the incident photon conversion efficiency （IPCE） shows an enhancement with a factor of 3, which even exceed 54% at 400 nm wavelength. We believe the enhancement is attributed to several facts including improvement in absorption, reacting area, carder localization and carrier lifetime.

Experimental Study of Plasma Under-liquid Electrolysis in Hydrogen Generation

The application and characteristics of relatively big volume plasma produced with cathodic glow discharges taking place across a gaseous envelope over the cathode which was dipped into electrolyte in hydrogen generation were studied. A critical investigation of the influence of methanol concentration and voltage across the circuit on the composition and power consumption per cubic meter of cathode liberating gas was carried out. The course of plasma under-liquid electrolysis has the typical characteristics of glow discharge electrolysis. The cathode liberating gas was in substantial excess of the Faraday law value. When the voltage across the circuit was equal to 550 V,the volume of cathodic gas with sodium carbonate solution was equal to 16.97 times the Faraday law value. The study showed that methanol molecules are more active than water molecules. The methanol molecules were decomposed at the plasma-catholyte interface by the radicals coming out the plasma mantle. Energy consumption per cubic meter of cathodic gases (WV) decreased while methanol concentration of the electrolytes increased. When methanol concentration equaled 5% (-),WV was 10.381×103 kJ/m3,less than the corresponding theoretic value of conventional water electrolysis method. The cathodic liberating gas was a mixture of hydrogen,carbon dioxide and carbon monoxide with over 95% hydrogen,if methanol concentration was more than 15% (-). The present research work revealed an innovative application of glow discharge and a new highly efficient hydrogen generation method,which depleted less resource and energy than normal electrolysis and is environmentally friendly.

Hydrogen Generation by Splitting H2O Molecule on the Pt6Cu Cluster

Seven reaction paths for hydrogen generation from water molecule with Pt6Cu cluster are identified, based on the density functional theory with exchange-correlation functional in Becke＇s three-parameter form. The complex structures of the reactant H2O@Pt6Cu and the structures of the products H2＋O@Pt6Cu and H＋OH@Pt6Cu on various adsorption sites of Pt6Cu cluster are optimized and the energy stability of the structures is confirmed by frequency analysis. The geometries of the transition states and the intrinsic reaction coordinate are also determined at the same theoretical level. The energy barrier for each reaction is calculated. The results demonstrate that the Pt6Cu cluster can abstract one H atom from H2O molecule with one step reaction by overcoming a moderate energy barrier. These findings can be helpful for understanding the mechanism to produce hydrogen from a water molecule with Pt6Cu cluster.

Surface Modification of Titanium Oxide by Indium for Efficient PhotocatalyticHydrogen Generation

We fabricated indium ion-modified TiO2nanoparticles. The results revealed that indium presents on TiO2surface in the form of fixed ion, by coordinating with hydroxyl groups or terminal oxygen atoms at the surface of TiO2, which resulted in smaller grain size, larger surface area, and mesoporous structure relative to pure titanium dioxide. Compared with pure TiO2, indium ion-modified TiO2showed great enhancement of photocatalytic activity to hydrogen generation. Owing to electronic capture capability of indium, the excited electrons can rapidly transfer from TiO2conduction band to indium, resulting in the separation of electron-hole pairs. The optimal H2 evolution rate was 277.8 mmol·g-1·h-1, which was about 23 times higher than that of Degussa P25.

Parallel Correlative Study of the Heat Balance Test Process for Testing the Efficiency of Turbo-Generators

In order to prolong the life span of a turbo-generator plant and sustain its performance at high efficiency, it is subjected periodically to regular test to monitor the operational profile and efficiency of power conversion from mechanical energy to electrical energy. Analysis of these test data serves as a measure to indicate deviation from normal operation profile and deterioration of plant performance. This present work implemented the heat balance tests process to three turb- generator units in order to assess the harmony, consistency, and accuracy of results to establish parallel correlation for the test process. The test process involves carrying out a heat balance for the turbo-generators at 50%, 75% and 100% load respectively through the determination of the heat losses through the hydrogen coolers, bearing oil, seal oil and radiation and convention to the atmosphere. Some important results were presented in the paper.

Nickel boride alloys as catalysts for successive hydrogen generation from sodium borohydride solution

Nickel boride alloys,Ni-B,were prepared using chemical reduction method by the reaction of metal chloride with sodium borohydride,and heat-treated at various temperatures. The structures of the as-prepared alloys were studied using X-ray diffractometry(XRD),scanning electronic microscopy(SEM) and nitrogen adsorption-desorption analysis. When being adopted as the catalysts for successive hydrogen generation from sodium borohydride solution,the Ni-B alloy treated at 90 ℃ achieves a maximum hydrogen generation rate of 15.4 L/(min·g),and an average hydrogen generation rate of 13.6 L/min,which can give successive hydrogen supply to a 2.2 kW PEMFC at a hydrogen utilization of 100%.