Three dimensional heat and mass transfer in a metal-hydrogen reactor are numerically studied using the control-volume-based finite element method (CVFEM).The distributions of the temperature and the hydride density on the hydriding process is presented and discussed. The effects of dimensions reactor, imposed hydrogen pressure, inlet temperature and hydride thermal conductivity in the reaction ...

In order to find out the optimal composition of novel Nd-Mg-Ni alloys for hydrogen storage, the isothermal section of Nd-Mg-Ni system at 400 °C is established by examining the equilibrated alloys. A new ternary compound Nd4Mg80Ni8 is discovered in the Mg-rich corner. It has the crystal structure of space group I41/amd with lattice parameters of a = b = 11.2743(1) Å and c = 15.9170(2) Å, charact...

The hydriding kinetics of MINi, before and after activation were studied experimentally and discussed in terms of the models presented in Part I. The parameters in the kinetic equations previously obtained were determined. The experimental data were in excellent agreement with the equations. The results indicate that the first hydrogenation process is a phase transformation process, in which th...

the hydrogenation characterizations of the hydrogen storage alloy mmni4.22co0.48mn0.15al0.15 (mm= mischmetal), and the effect of hydrogenation/dehydrogenation (h/d) cycling on its structural and morphological properties are investigated. the results indicate that after several h/d cycles the alloy was pulverized into fine particles, but it kept its hexagonal cacu5-type structure. the pressure-c...

Using a new indirect nanoplasmonic sensing method with subsecond resolution, we have studied hydriding and dehydriding kinetics of Pd nanoparticles in the size range 1.8-5.4 nm. Strong particle-size effects are observed. The scaling of the hydriding and dehydriding time scales satisfies power and power-exponential laws. The former (with an exponent of 2.9) is in perfect agreement with Monte Car...

This two-part study explores the development and thermal performance of a coiled-tube heat exchanger for hydrogen fuel cell storage systems utilizing High-Pressure Metal Hydride (HPMH). The primary purpose of this heat exchanger is to tackle the large amounts of heat released from the exothermic hydriding reaction that occurs when the hydrogen is charged into the storage vessel and is absorbed ...

A mathematical model f or the electrochemical impedance spectroscopy of a metal-hydride electrode was developed. The model was used to study the effect of various parameters on predicted kinetic behavior. The simulations obtained using the model show that the first arc appearing in the higher frequency range is due to a charge-transfer reaction, the second arc in the middle frequency range repr...

The present study deals with the experimental and theoretical approaches of LaNi5 hydrogen storage alloy. The structural, morphological and hydrogenation characterization of this sample which is synthesized by the arc melting technique were carried out by X-ray diffraction, scanning electron microscopy and a homemade Sievert's type apparatus, respectively. The results showed that after several ...

The hydriding kinetics of hydrogen storage materials in the two-phase regions have been studied. It is believed that the hydriding process is best classified into three steps: dissolution of hydrogen into the alloy or its hydride; diffusion of hydrogen atoms through the alloy or its hydride phase; and nucleation and growth of B-hydride (hydride depositing from supersaturated a-solid solution). ...

Magnesium hydrides are considered as the potential hydrogen storage materials. However, high work temperature, slow reaction kinetics and hard activation process limit the practical application of Mg-based hydrides system. Recently, the reaction ball milling (RBM) technique has been successfully introduced to prepare hydrogen storage materials [1, 2]. It combines the courses of sample preparati...