摘要：Hydrogen combustion attracted much attention recently because of the need for a clean alternative energy. For the theoretical/numerical study of hydrogen combustion, there is a need for modeling capabilities for turbulent hydrogen flames. The present work examines the applicability of probability density function (pdf) turbulence models. For the purpose of accurate prediction of turbulent combustion, and algorithm that combines a conventional CFD flow solver with the Monte Carlo simulation of the pdf evolution equation has been developed. The algorithm is validated using experimental data for a heated turbulent plane jet. A study of H_2-F_2 diffusion flames has been carried out using this algorithm. Numerical results show that the pdf method is capable of correctly simulating turbulence effects on hydrogen combustion.
摘要：Unlike the rutile; the anatase phase of TiO_2 has not been extensively employed for fabrication of PEC cells primarily due to the difficully in the synsthesis of a stable anatase structural variant. The present investigation is focused on the synthesis of the anatase phase and its use as a photoelectrode of high efficiency PEC Solar Cells. TiO_2, in the nanostructured form, has been prepared by the hydrolysis of Titanium (IV) isopropoxide solution. The nanostructured TiO_2 (anatase) stable phase has been synthesised by sintering the synthesised film at ～ 500 deg C with a heating rate of 1 deg C/min for a duration of 3 h in argon. The films of nanostructured TiO_2 anatase phase have been used as photoelectrodes in PEC solar cells.
摘要：In a combined p-c and R/Ro-c study of Pd-5 and 9.9 at. Ag-D systems by a gas phase method, a remarkable pressure and resistance hysteresis are observed between 298-323 K. Pressure hysteresis are gradually decreased with increasing the silver content. R/Ro value increases with increasing D/M content up to α_(max) compositions. In the (α+β) two-phase region, R/Ro shows only a small increase. From β_(min), R/Ro increases abruptly with increasing D/M content.
摘要：The aim of the present paper is to evaluate the thermodynamic yields for a direct methane catalytic partial oxidation (CPOX) in a molten carbonate fuel cell (MCFC), operating with or without a cogeneration bottoming cycle. The influence of several operating parameters on the mass and energy balances of a 10 kW power plant has been investigate by using a mathematical model. The temperature, the methane inlet flow, the fuel utilisation coefficient, the electrical power and the useful heat fraction have been found to be relevant parameters to investigate the behaviour of the system.
摘要：In the present paper the steam cycle proposed by Spazzafumo has been again taken into consideration and the effect of the flow variation on the cycle performances has been investigated. The isothermal expansion with increasing flow causes a decrease in cycle efficiency due to the greater condenser losses and, at high superheated temperatures, to the impossibility of full recovering of the available heat at the end of the expansion. However, using part of this heat for preheating the required hydrogen and oxygen, yields a significant increase in efficiency.
摘要：A good correlation has been obtained between the existence of hydrogen reservoirs in solids revealed by a dynamic method of titration and an in-situ X-ray diffraction analysis under H_2. The dynamic method of titration involves hydrogenation at 423 K of 2-methylbuta-1, 3-diene(isoprene) under helium flow in the absence of gaseous hydrogen and permits to reveal and titrate reactive hydrogen species (H) that a solid is able to store. Different compounds, such as a CeNi_(1.5)O_(2.5) mixed oxide and a Cs(1.6)(NH_4)_(2.4)P_(1.7)Mo_(11)V_(1.1)O_(40) polyoxometalate, are found to be hydrogen reservoirs with marked diffusion properties of hydrogen species. The hydrogen reservoir capacity depends on the pretreatment temperature under H_2, which has been shown to correspond to the creation of anionic vacancies in the solid by the loss of H_2O. In the conditions in which the incorporation of hydrogen in the solids occurs, X-ray diffraction analysis under H_2 show shifts depending on the treatment temperature and corresponding to a lattice expansion attributed to the insertion of hydrogen species of hydridic nature in the anionic vacancies.
摘要：This paper deals with the preparation of the amorphous Mg-Ni alloys. By mechanical alloying (MA) the amorphous Mg-Ni alloys with different compositions have been prepared of pure elemental magnesium and nickel powder. The asmilled powder was characterized by X-ray diffraction analysis and transition electron microscope (TEM) observation. The results showed that the 30 < Ni < 70 /100at. composition could be amorphized with a milling time strongly dependent on the starting chemical compositions. The investigation on the early stage of MA showed that the different compositions amorphized by two different paths. On the magnesium rich side of 30-70 at/100. Ni, the as-milled powders first formed the intermetallic compound Mg_2Ni, which sbusequently destabilized into the amorphous phase. For the nickel rich side, the amorphous was obtained directly form the mechanical blend of magnesium and nickel powder by the suppression of the formation of formation of thermodynamic equilibrium phase MgNi_2.
摘要：The oxygen evolution reaction (OER) was investigated at 60 deg C in 15 wt NaOH solution on NiCo_2O_4 electrodes. Nickel-cobalt oxides were obtained by different preparation techniques and they were applied to chemically pickled nickel plates. Fresh and artificially aged electrodes were subjected to electrochemical performances was performed for 21 days. The correlation between the coating preparations and their electrochemical performances was investigated by analysis of the electrochemical data. The efficiency of the NiCo_2O_4 electrodes changed significantly with the changing of the preparation method. Two Tafel slopes for the OER were observed in most cases. This behaviour was interpreted on the basis of a change in the valence state of the oxide. The kinetic parameters obtained on NiCo_2O_4 electrodes were compared and discussed according to the preparation methods.
摘要：Photolysis of silver chloride in aqueous medium resulted in the formation of silver clusters and the evolution of oxygen form water. These silver clusters, when photooxidized in the presence of aqueous potassium iodide solution resulted in hydrogen being evolved form water. Preliminary laser investigations were carried out to confirm the proposed mechanism. The photooxidation process may possibly be applied to recycle silver from exposed photographic film wastes and as a means of converting solar energy, with simultaneous evolution of hydrogen.
摘要：Hydrogen diffusion behavior in Mg_2Ni-type hydrogen storage alloy electrodes was characterized by using both potentiostatic polarization method, based on a spherical diffusion model, and electrochemical impedance spectroscopy (EIS) technique. The values of the diffusion coefficients of hydrogen in Mg_2Ni and Mg_(1.9)V_(0.1)Ni_(0.8)Al_(0.2) are 1.2×10~(11) ～ 1.57×10~(-10) and 3.1 ～ 7.6×10~(-9) cm~2/s, respectively. The values of diffusion coefficients decline notably with the increase in depth of discharge (DOD). The decay rate of diffusion coefficient in Mg_2Ni with DOD is much quicker than that in Mg_(1.9)V_(0.1)Ni_(0.8)Al_(0.2). The experimental results suggested that the substitutions of V and Al for Mg and Ni in Mg_2Ni could significantly improve the hydrogen diffusion performance in this alloy and thus substantially increase discharge capacity of the electrode.
摘要：The Fachhochschule Wiesbaden has developed and operated two decentral energy-systems of hydrogen-technology where the hydrogen serves as storage-medium for solar and wind-energy. The principal economical results are described. It is evident that the hydrogen-price is too high for energy-technology. One of the reasons is the high storage-price for pressurized hydrogen. A price-reduction is possible if also the electrolytical oxygen is used, for instance in a waste-water purification plant. The storage problem can be solved if one lets react the hydrogen with carbon dioxide. The reaction product is methanol, a liquid energy-carrier for which exists the distribution infrastructure. The principles of this energy-technology (to store energy by reaction-products of hydrogen and carbon-dioxide) are known, because nature has applied it for millions of years in plants.
摘要：The effect of the Cu/Ni ratio on CO_2 hydrogenation at 773K and 873K was studied by XRD, TPR, H_2 and CO_2-TPD. There exists strong interaction between Cu and Ni components. At high temperature (773K and 873K), the products are CO, CH_4 and H_2O without CH_3OH formation. The Cu/Ni ratio has a significant effect on the conversion and selectivity. Cu factors CO formation while Ni is of benefit in CH_4 formation.
摘要：This paper discusses the results of an experimental study of a new method of natural gas pyrolysis based on thermal decomposition in a flow of high temperature carrier gas preliminary heated in the regenerative heater matrix. It has been shown that in this case the methane carbon is almost completely converted into black carbon and no pyrocarbon is produced in the reaction volume.
摘要：Photoproduction of hydrogen has been studied as one of the ways to produce a clean, renewable energy source. Here, a combination of cells using Phormidium valderianum, Halobacterium halobium and Escherichia coli was used to produce hydrogen. An immobilized system was far more stable than the free cells and produced hydrogen continuously over 60 days, under on/off light (6h) and dark (18h) cycles. The optimal conditions for maximal production of hydrogen were then standardized.
摘要：Hydrogen production from the wastewater of tofu factory was examined by using anoxygenic phototrophic bacterium Rhodobacter sphaeroides immobilized in agar gels. The maximum rate of hydrogen production observed from the wastewater was 2.1 1 h~(-1) m~2 gel which was even slightly higher than that from a glucose medium (as control). The hydrogen production lasted up to 50h. The yield of hydrogen was 1.9 ml/ml wastewater or 0.24 ml/mg carbohydrates contained in the wastewater. This yield corresponds to 53 or 65 of that from the glucose medium, according to the different expressions of the yield. The TOC (total organic carbon) removal ratio in 85 h reached 41 which was comparable to that from the glucose medium. The immobilization protected the bacterium from the inhibitory effect of ammonium ion.
摘要：Considering energy crises and pollution problems today, investigations have been concentrated on decrasing fuel consumption by using alternative fuels and on lowering the concentration of toxic components in combustion products. In the present work a quasi-dimensional model was developed to study the effect of hydrogen blending on fuel consumption and pollutant concentrations. The results of the study show that the maximum improvement in engine thermal efficiency occurs at 8/100 hydrogen blending. The results also show that 10/100 hydrogen blending reduces CO concentration by 73.8/100 but the NO concentration increases by 100/100. However the problem of increasing NO concentration was solved by operating the engine with lean mixture. Hydrogen blending also reduces the specific fuel consumption until about 6 blending, then the effect becomes marginal.
摘要：Photovoltaic tandem cells, consisting of a gallium indium phosphide (GaInP_2) homojunction grown epitaxially on a gallium arsenide (GaAs) homojunction with a GaAs tunnel diode interconnect, were modified with an additional top p-layer of GaInP_2. These cells were used as electrodes to photoelectrochemically decompose water into hydrogen and oxygen in 1M, 5M, and 1M KOH electrolyte solutions. The hydrogen reaction was catalyzed at the semiconductor surface with a photoelectrochemically deposite thin layer of platinum and rughenium. Gas chromatography and electrochemical experiments demonstrate that the modified tandem cells produce hydrogen and oxygen with a light-to-hydrogen conversion efficiency of up to 6/100. Both the efficiency and the stability of these cells are discussed.
摘要：Oxidative removal of a small quantity of CO from hydrogen atmosphere has been attempted by using catalysts consisting of 3d transition metal oxides. The oxidation of CO takes place in preference to that of H_2 on catalysts containing Co or Mn in a temperature range from 323-423 K. At higher temperatures, the oxidation of H_2 becomes to coincide and then the selectivity to the CO oxidation decreases. Hydrogenation of CO giving methane also occurs over the catalysts containing Ni or Co. Reduction of catalysts at high temperatures might be the reason for the observed change in the catalytic properties. Among the catalysts tested, CoO showed the best performance and was considered to be one of the candidates for the refinement of the hydrogen fuel for the polymer-electrolyte type fuel cells (PEFCs).
摘要：This paper presents the results of an experimental investigation o natural gas pyrolysis at a hot matrix in a high temperature regenerative gas heater. It was demonstrated that formation of pyrocarbon during thermal decomposition of natural gas significantly influences upon the process efficiency. Burn out of the carbon deposits from the matrix during the matrix heating up stage produces components harmful to the environment. To make the pyrolysis process effective and environmentally benign it is necessary to provide special measures to exclude the possibility of pyrocarbon formation during the pyrolysis.
摘要：Deuterium and hydrogen migration and release have been studied in stainless steel, niobium, palladium during accelerated electrons and ~(14)N ions. It was shown that radiation stimulates the intensive release of electrolytically introduced deuterium from stainless steel, Pd and Nb. The mechanism release of deuterium from metals under the influence of radiation released with accumulative properties of internal D(H) atmosphere and influence of ionizing radiation on potential surface barrier preventing formation of D_2 (H_2), molecules and its desorption in gas phase.