International Association For Hydrogen Energy Research Articles

A prediction study of the effect of hydrogen blending on the performance and pollutants emission of a four stroke spark ignition engine

Considering energy crises and pollution problems today, investigations have been concentrated on decreasing 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% hydrogen blending. The results also show that 10%hydrogen blending reduces CO concentration by 73.8% but the NO concentration increases by100%. However the problem of increasing NO con- centration 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. 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

Hydrogen production from tofu wastewater by Rhodobacter sphaeroides immobilized in agar gels

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 l h −1 m 2 gel which was even slightly higher than that from a glucose medium (as control). The hydrogen production lasted up to 50 h. The yield of hydrogen was 1.9 ml⧸mlwastewater or 0.24 ml⧸mg carbohydrates contained in the wastewater. This yield corresponds to53% 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. © 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

Hydrogen and oxygen evolution from water using Ag and AgCl colloids

Photolysis of silver chloride in aqueous medium resulted in the formation of silver clusters and the evolution of oxygen from water. These silver clusters, when photooxidized in the presence of aqueous potassium iodide solution resulted in hydrogen being evolved from 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.©1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

Probability density function method for turbulent hydrogen flames

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, an 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. © 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

Catalytic partial oxidation of methane in a molten carbonate fuel cell

The aim of the present paper is to evaluate the thermodynamic yields for a direct internal 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 investigated 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. The examination of the results shows that the highest generated electrical power corresponds to a fuel utilisation coefficient of 80%, with a very appreciable methane conversion. The electrical efficiency obtained for the examined system is lower than that from a direct methane steam reforming monocell (DIR MCFC), but the exhaust gas composition seems to be usefully adoptable for the production of organic compounds. The overall system efficiency strongly improves if the thermal energy available is fully or partially recovered. In these cases, the theoretical energy efficiency ranges from 100% to 54.9%. All the evidence indicates that this system appears very flexible for applications in plants for the production of syngas for CH3 OH or NH3 sintesys where the electricity is a by-product. These interesting opportunities require a further investigation on some detrimental aspects that could affect the methane CPOX fuelled MCFC. 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

Electrochemical study of hydrogen diffusion behavior in Mg 2Ni-TYPE hydrogen storage alloy electrodes

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 1.9V 0.1Ni 0.8Al 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 1.9V 0.1Ni 0.8Al 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. © 1998 International Association for Hydrogen Energy

Hysteresis of pressure-composition and electrical resistance-composition isotherms of palladium-silver alloys-deuterium system

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 amax 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. On desorbtion, R/Ro value decreases with decreasing D/M contents down to bmin and then remains almost constant in the (α+β) two-phase region. From α max(des), R/Ro sharply decreases to a minimum value. Finally, a large resistance hysteresis is observed in the (α+β) two-phase region. Such R/Ro-c hysteresis indicates that the creation of lattice strain deformations accompanied of dislocations for the β deuteride formation are not fully annihilated during the decomposition of β deuteride. The hysteresis is decreased with increasing temperature and silver content. For the Pd-5 at.% Ag-D system, no resistance hysteresis is observed between 348-398 K. In this case, R/Ro value is increased abruptly up to amax composition. (D/M)α max is appeared after a long holding. In the (α+β) region, R/Ro remains almost constant but decreases with increasing temperature. In this region, the dislocation densities for the a tb transformations behave as equal in quantity and R/Ro is insensitive to small change in dislocations. The sharp increment of R/Ro values up to (D/M)α max seems to be related to the Gorsky effect. The absence of resistance hysteresis indicates that the plastic deformations created due to the b deuteride formation are fully annihilated during its decomposition. Presently observed p-c and (R/Ro)-c behaviours are analogous to that found previously for Pd-H(D) and Pd-5 and 9.9 at.% Ag-H systems. 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

On the preparation of amorphous Mg–Ni alloys by mechanical alloying

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 as-milled powder was characterized by X-ray diffraction analysis and transition electron microscope (TEM) observation. The results showed that the 30 < Ni < 70 at.% 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.% Ni, the as-milled powders first formed the intermetallic compound Mg 2Ni, which subsequently destabilized into the amorphous phase. For the nickel rich side, the amorphous was obtained directly from the mechanical blend of magnesium and nickel powder by the suppression of the formation of thermodynamic equilibrium phase MgNi 2. © 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

Production of hydrogen and methanol from natural gas with reduced CO 2 emission

The thermal decomposition of natural gas forms the basis for the production of hydrogen with reduced CO 2 emission. The hydrogen can be used to reduce CO 2 from coal-fired power plants to produce methanol which can be used as an efficient automotive fuel. The kinetics of methane decomposition is studied in a one inch diameter tubular reactor at temperatures between 700 and 900 °C and at pressures between 28 and 56 atm. The Arrhenius activation energy is found to be 31.3kcal/mol of CH 4. The rate increases with higher pressures and appears to be catalyzed by the presence of carbon particles formed. The conversion increases with temperature and is equilibrium limited. A thermodynamic study indicates that hydrogen produced by methane decomposition while sequestering the carbon produced requires the least amount of process energy with zero CO 2 emission. Application to methanol synthesis by reacting the hydrogen with CO 2 recovered from coal burning power plant stack gases can significantly reduce CO 2 from both the utility and transportation sectors. Published by Elsevier Science Ltd on behalf of the International Association for Hydrogen Energy.

98/01324 Voltage regulation algorithm for a bi-phase distribution system feeding residential customers using a Beta p.d.f. load model: Herman, R. and Maritz, J. S. Electric Power Systems Research, 1997, 43, (2), 77–80

The aim of the present paper is to evaluate the thermodynamic yields for a direct internal 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 investigated 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.The examination of the results shows that the highest generated electrical power corresponds to a fuel utilisation coefficient of 80%, with a very appreciable methane conversion. The electrical efficiency obtained for the examined system is lower than that from a direct methane steam reforming monocell (DIR MCFC), but the exhaust gas composition seems to be usefully adoptable for the production of organic compounds. The overall system efficiency strongly improves if the thermal energy available is fully or partially recovered. In these cases, the theoretical energy efficiency ranges from 100% to 54.9%. All the evidence indicates that this system appears very flexible for applications in plants for the production of syngas for CH3 OH or NH3 sintesys where the electricity is a by-product. These interesting opportunities require a further investigation on some detrimental aspects that could affect the methane CPOX fuelled MCFC. 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

97/04603 Hydrogen production from fossil fuels and other regionally available feedstocks: Timpe, R. C. et al. Hydrogen Energy Prog. XI, Proc. World Hydrogen Energy Conf., 11th, 1996, 1, 489–498. Edited by Veziroglo, T. N. International Association for Hydrogen Energy, Coral Gables, FL

97/04603 Hydrogen production from fossil fuels and other regionally available feedstocks: Timpe, R. C. et al. Hydrogen Energy Prog. XI, Proc. World Hydrogen Energy Conf., 11th, 1996, 1, 489–498. Edited by Veziroglo, T. N. International Association for Hydrogen Energy, Coral Gables, FL

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International Association for Hydrogen Energy

International association for hydrogen energy

International association for hydrogen energy

International association for hydrogen energy

International association for hydrogen energy

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