Fuel cells

Modelling of chemically induced stresses in tubular membranes with mixed oxygen-ionic and electronic conductivity

By the example of tubular oxygen-permeable membrane of mixed-conducting LaGa0.65Mg0.15Ni0.20O3-Δ operating under oxygen chemical potential gradients in the regime of hydrocarbon oxidation, modeling of chemically induced strains in the dense ceramic material has been carried out. The membranes with various radii in different reactor configurations were simulated. Analysis of the distributions of oxygen chemical activity and chemically induced stresses showed that, for minimization of mechanical stresses, the most advantageous basic configuration involves supplying atmospheric air inside a tubular membrane and opposite directions of the gas flows. The maximum stresses are observed in the region of reducing gas mixture injection, where a zone with an essentially constant oxygen chemical potential on the membrane surface may exist for many reactor configurations. The size of such zones formed due to specific features of the gaseous phase component distribution and/or ceramic reactor configurations, has a significant effect on the mechanical stress distribution.

Oxyge electro-reduction in an acidic electrolyte on the gold nanoparticles–carbon carrier system

The synthesis of catalysts 20 Au/C with different degree of dispersion. These systems were investigated for activity in the oxygen electroreduction reaction with methods of the cyclic voltammograms and polarization curves. The increase of rate and depth of process (the number of electrons increases from 2 to 3.5) in the transition from compact to gold nanoparticles.

Electrical conductivity and thermal expansion materials on the basis of Pr2-ySryNi1-xCuxO4 (x = 0/1: y = 0/0.15) for cathode of medium temperature electrochemical devices

The phase composition, thermal coefficient of linear expansion and electrical conductivity of r1.85Sr0.15Ni1-xCuxO4 (0.0; 0.1; 0.5; 0.9 и 1), Pr2NiO4 and Pr2CuO4 are investigated at air in the temperature range 100-1000°C.
The thermal coefficient of linear expansion are in range of ((11.2–16.6)·10-6 deg-1. The TCLE of some composition close to TCLE of solid electrolyte La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM) и Ce0.9Gd0.1O2-Δ (CGO). Pr1.85Sr0.15Ni0.1Cu0.9O4 has the highest conductivity at temperatures above 350°C.

Operation life of hydrogen-oxygen fuel cell with alkaline matrix electrolyte

The paper presents the performance of domestic PHOTON hydrogen-oxygen alkaline fuel cells. The issues of FC operation life is discussed, and reasons for reversible and irreversible voltage degradation are identified. The input of FC components into irreversible part of performance degradation is estimated.

A stability study of platinized carbon black and carbon nanotubes nanocomposite as a fuel cell electrocatalyst

By cyclic voltammetry and rotating disk electrode investigated the stability of the composite catalyst Pt/C–CNT from electrochemical action through multiple changes of the electrode potential from –150 to 1000 mV vs. silver chloride reference electrode. Investigated: the dynamics of the electrochemically active surface area of platinum and electrode in whole, change of amount of quinone groups, change in density of the kinetic current reduction of air oxygen on the surface of the catalyst. With the use of the method of differential thermal analysis studied the oxidation processes and the mechanisms of change of the physicochemical properties of the material under electrochemical action.

The influence off different factors on the temperature distribution in the battery solid oxide fuel cells

The thermal model of the power plant based on the solid oxide fuel cells (SOFC) fed with methane is developed. The power plant includes three heat-generating zones: a fuel-cell stack, a reactor of partial oxidation (RPO), and an afterburner. It is shown that temperature distribution along the battery depends on three factors: a methane consumption, a methane to air relation in the flow fed to the RPO, and a battery current. Results of modeling well correlate with the experimental data received on the power plant prototype with the SOFC stack consisted on 16 tubular cells.

Investigation of the high-temperature proton-exchange membrane fuel cell and calculation of the efficiency of the electrochemical power installations on its basis

A high-temperature solid polymer electrolyte fuel cell using H 3 PO 4 -doped polybenzimidazole (PBI) as proton-exchange membrane has been developed and tested. The influences of temperature (in a range between 130 and 170°C), pressure (in a range between 1 and 3 bars) and air flow rate onto fuel cell performances have been studied. A maximum output power density of 200 mW·cm-2 has been obtained. The existence of an optimum air flow rate (expressed in oxygen stoichiometric ratio) has been put into evidence. It allows an increase of the fuel cell voltage from 250 mV up to ca. 400 mV at 0.4 A·cm-2. The results of the calculation of efficiency of PBI-based electrochemical power plant using the products of natural gas conversion as a fuel are presented.

Heat balance analysis of solid oxide fuel cell battery

The paper analyzes the energy balance of the solid oxide fuel cell (SOFC) battery. The existence of three temperature points satisfying the equation of SOFC battery energy balance is found out. The first point is trivial and corresponds to the cooled state of the battery. The second temperature point corresponds to an unstable state of the battery and finally, the third point is stable and corresponds to the normal operating state of the battery. The difference between the third and second point defines the temperature interval within the battery is able to self-heating. Analogy with the Semenov diagram for chemical reactors is noted.

Long-term testing of hydrogen-oxygen alkaline matrix fuel multicell stacks

The paper generalizes a many years' experience in manufacturing and testing of multicell PHOTON stacks based on hydrogen-oxygen alkaline matrix fuel cells. Inter-cell processes effecting the stack lifetime are concerned, the main of which is the current flow between cells along a thin electrolyte film in gas collectors. This process is accompanied by electrolyte redistribution among elements resulting in their polarity reversal, and electrochemical corrosion in metal gas collectors of stacks.

Carbon nanotubes supported core–shell catalysts Pt-Ru/Ni, Pt-Ru/Pb and Pt-Ru/Ni for methanol oxidation reaction in fuel cell

The core-shell type catalysts were obtained by spontaneous surface substitution of electrodeposited Pb, Ni and Cu by platinum metals Pt-Ru. The surface layer of obtained catalysts was tested by EDAX; the amount of platinum was determined by ICP-AES. The catalytic activity of obtained catalysts was examined in methanol oxidation reaction. The stationary state currents were referred to EAS, determined from hydrogen adsorption. For all investigated systems the catalytic effect was registered thus confirming the activity of core–shell catalyst.