Journal of Hydrogen, Fuel Cell and Energy Storage
Volume:1 Issue: 1, Winter 2014

A palladium composite membrane was prepared by electroless plating on oxidized porous stainless steel support (ox-PSS). Hydrogen permeation flux through this composite membrane was measured in the temperature range of 574-674K and the pressure difference of two sides of membrane up to 90kPa. A simplified resistance model was employed to analyze the permeation behavior of hydrogen through Pd/ox-PSS membrane for calculating the contribution of each layer in resistance against the hydrogen transport. The amount of enthalpy of hydrogen dissolution of palladium membrane is -9.4kJ/mol. Considering a complete detailed model, this value was used for discussing the effect of interaction of metal- support on hydrogen exiting from the palladium layer at the downstream side. Several composite membranes which differ in support material has been compared with each other. It was confirmed that the metal-support interaction, plays an effective role in exiting activation energy. In Pd/ox-PSS composite membrane, the metal-support interaction decreases hydrogen exiting rate from Pd membrane’s downstream side.

The preparation of air–fuel mixture is considerably dependent on fluid flow dynamics to achieve improved performance, efficiency, and engine combustion in the appearance of flow. In this study, the effects of mixtures of hydrogen and compressed natural gas (CNG) on a spark ignition engine are numerically considered. This article presents the results of a direct-injection engine using methane–hydrogen mixtures containing H2 between 0% and 15% by volume. The result shows that the percentage of hydrogen in the CNG increases the burning velocity of CNG and reduces the optimal ignition timing to obtain the maximum peak pressure of an engine running with a blend of hydrogen and CNG. With hydrogen addition to natural gas, the peak heat release rates increase. For 15% hydrogen, the maximum values at crank angles (CAs) for in-cylinder temperature and heat release rate are achieved at 8° CA, and the maximum temperature is approximately 150 K. Port injection gasoline is converted into direct injection by CNG fuel in this engine.

In the present study، Mn - Cr spinel powder was synthesized through a solid state reaction. In the next step، the electrophoretic deposition (EPD) method was used to apply the MnCr2O4 spinel، as an oxidation-resistant layer، on SUS 430 stainless steel in a potential of 300 V/cm. The coated and uncoated samples were then pre-sintered in air at 900 °C for 3 h followed by cyclic oxidation at 800 °C for 500 h. In order to study the effect of reducing pre-sintering atmosphere on oxidation resistance، the coated specimen was pre-sintered in 5% H2 / Ar at 900 °C for 3 h followed by cyclic oxidation at 800 °C for 500 h. The investigation of the oxidation resistance of the samples revealed that the MnCr2O4 spinel coating improved the oxidation resistance of the uncoated sample and also، the oxidation rate constant (Kp) for pre-sintered coating in 5% H2 / Ar was nearly 14 times smaller than that of the one pre-sintered in air.

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 hydrogenation/dehydrogenation cycles, disproportionation occur in LaNi5. The hydriding kinetic measurements under different applied pressure show that the hydrogen storage capacity (Cwt.%) increases with pressure. However, kinetic analysis at different temperatures under constant initial pressure, which is fitted to two models such as Jander diffusion model and Johnson-Mehl-Avarmi, revealed that Cwt.% and hydriding reaction rate are decreased and increased by increasing of temperature, respectively. The theoretical study using full potential linearized augmented plane wave plus local orbitals method was also performed to investigate the structural, energetic and electronic properties of LaNi5 and its saturated hydride (LaNi5H7). From the two possible space groups for LaNi5H7, P63mc was found as the most favorable one. A volume expansion of ~%26 was found for its hydride. Other calculated results including the equilibrium atomic positions, bulk modulus and the enthalpy of formation were in good agreement with other theoretical and experimental results. The band structure calculations showed that the valence bands were mainly derived from Ni-3d states, and the bandwidth of the occupied Ni-3d bands in hydride phase was narrower than that of the parent compound due to the filling of Ni-3d bands as a result of hydrogen absorption and volume expansion.

In this paper the role of super paramagnetic iron oxide nanoparticles (SPI) on Platinum nanoclusters on activated carbon (Pt/C) for electrocatalytic oxygen reduction reaction was considered. Four composites of Pt/C and super paramagnetic iron oxide nanoparticles were prepared with the same total composites weight and different loading of Pt/C (1.2, 0.6, 0.4 and 0.3 mg). The composite attached on a glassy carbon electrode via a thin layer of Nafion, that was made by Nafion solution. The electrochemical tests were carried out by using conventional three electrode system in sulfuric acid electrolyte at room temperature. Cyclic voltammetry, linear sweep voltammetry, rotating disk electrode configuration and chronoamperometry results showed that by decreasing the Pt/C loading, Electroactive surface area and oxygen diffusion coefficient decreased. Also by increasing the Fe3O4 nanoparticles in catalyst composite 2-electron pathway for ORR surpass from 4- electron pathway. Our results showed that in electrode with the same ratio of Pt/C and SPI has the best utilization of Pt for oxygen reduction reaction.

The CO preferential oxidation (PrOx) is one of the critical steps in hydrogen production and purification for Polymer Electrolyte Membrane Fuel Cell (PEMFC). This reaction was investigated in the presence of excess hydrogen over Cu/CeO2, Pt/CeO2 and Cu-Pt/CeO2 catalysts. The ceria supports was prepared via precipitation method and Cu-Pt/CeO2 catalyst was synthesized by sequential impregnation on ceria. The catalysts were characterized by XRD. Comparison of ceria supported copper and platinum showed that copper catalysts activity was higher than platinum in PrOx process. Effect of platinum addition on ceria supported copper was investigated and results showed that Pt promoter have positive effect on CO conversion in low temperature (<110ᵒC). Promotion of Cu with Pt increases the CO conversion 30% in comparison with unpromoted Cu catalyst. It is mentioned that the platinum addition to copper only promote the Cu catalyst at low temperature. In higher temperature reverse WGS reaction occurs and decreases the CO conversion.

In this paper, Plug-in Fuel Cell Electric Vehicle (PFCEV) is considered with dual power sources including Fuel Cell (FC) and battery Energy Storage. In order to respond to a transient power demand, usually supercapacitor energy storage device is combined with fuel cell to create a hybrid system with high energy density of fuel cell and the high power density of battery. In order to simulate the PEV model, dynamic state space models of bidirectional DCDCconverter and grid connected voltage source converter are considered to connect the PFCEVto the main grid. In order to stabilize the DC-link power and distribute the power between dualenergy storage sources in PEV during normal and disturbance conditions on the grid voltage, afuzzy control strategy has been developed. For tuning the parameters of fuzzy logic controller, the PSO (particle swarm optimization) algorithm has been used. This controller determines the super capacitor and fuel cell powers that should be generated according to the amount of available energy in DC-link. Moreover, a robust sliding mode control strategy for three phase power electronic converter based on positive and negative symmetrical components is presented to investigate the voltage disturbance ride-through capability.