Thermodynamical analysis of a hydrogen fueling station via dynamic simulation

This article describes the thermodynamical analysis of a hydrogen (${\text{H}}_2$) fueling station (HFS) with cryopump technology. A dynamic, object-oriented computer model of the HFS is developed in Matlab-Simulink. This model calculates, amongst other thermodynamic properties, the temporal and spatial variation of the ${\text{H}}_2$ temperature and the component temperatures within the HFS. The validation of the computer model with data from a series of measurements at a testing facility confirms a good accuracy of the model. The most important model object is the high pressure pipe through which the ${\text{H}}_2$ flows. The pipe is modeled and validated in different configurations. The thick-walled pipe material is discretized in radial and axial direction. In comparison to measurements the simulations show acceptable accuracy with an radial discretization length of $s<0.0026\text{m}$. In axial direction a discretization length of $l<1.18\text{m}$ is found to deliver acceptable accuracy of the simulations compared to measurements. Based on the simulation results a new method of controlling the ${\text{H}}_2$ temperature by mixing two ${\text{H}}_2$ mass flows with different temperatures is assessed as practicable. The electrical power requirement of the electric heat exchanger in this HFS design is determined. Depending on the load cases it varies between $0.13{\text{kWh}}_{\text{el}}/\left(\text{kg}{\text{H}}_2\right)$ and $0.40{\text{kWh}}_{\text{el}}/\left(\text{kg}{\text{H}}_2\right).$     

Path integral study on C15-type Laves TiCr2 hydride

The path integral method has been applied for the $C15$-type Laves alloy hydride, ${\text{TiCr}}_2{\text{H}}_{1.3}$, to treat quantum mechanical effects on atomic nuclei. The atomic interaction is simulated by the machine learning potential which reproduces well the results of density functional calculations. The canonical ensemble is sampled using the hybrid Monte Carlo method at 300 K. The predicted heat of solution, $-19\text{kJ}/\text{mol}{\text{H}}_2$, agrees well with the available experimental data. Hydrogen atoms dominantly occupy the $96g$ sites which form the closed hexagonal rings (HRs). Two H diffusion paths, the intra- and inter-HR paths, are identified, for which the activation barriers are evaluated to be 63 and 155 meV, respectively. They most likely correspond to different two H hopping modes assigned in the nuclear magnetic resonance experiment.     

Cobalt–copper–boron nanoparticles as catalysts for the efficient hydrolysis of alkaline sodium borohydride solution

Developing non-precious metal catalysts with high activity is crucial for the extensive applications of the proton exchange membrane fuel cell (PEMFC). Herein, we have prepared cobalt–copper–boron (Co–Cu–B) nanoparticles by a modified chemical reduction route where Ni foam was used as an initiation medium for the efficient hydrolysis of alkaline sodium borohydride (NaBH₄) solution. The influence of the synthetic condition (such as Cu²⁺ concentration, pH value and the concentration of reducing agent) on the catalytic activities has been explored. The catalytic hydrolytic tests reveal that the as-obtained Co–Cu–B nanoparticles with hollow spherical structure shows highly efficient catalytic activity, affording a hydrogen generation rate (HGR) of 3554.2 ${\text{mL}}_{{\text{H}}_2}·{\text{g}}_{\text{catal}.}^{-1}·{\text{min}}^{-1}$ under room temperature, and a lower activation energy of 52.0 kJ· mol⁻¹, which overtakes the activities of previous reported most non-precious metal catalysts, even some precious catalysts. The kinetics results show that the catalytic hydrolysis process of alkaline NaBH₄ solution is a zero-order reaction in view of the amount of Co–Cu–B catalyst, meaning that the reaction rate is independent of the catalyst amount. This study offers us a promising non-precious metal catalyst toward dehydrogenation from the hydrolysis of NaBH₄ to further speed up the application steps.