Specific features of operation of a membrane-electrode assembly of an air-hydrogen fuel cell

Specific features of the operation of the membrane-electrode assembly with high catalytic activity that are a part of the simplified design of a low-temperature air-hydrogen fuel cell under conditions of forced and natural convection of air on the cathode are studied. The governing effect of water balance on the specific power of the fuel cell in the stationary mode (～1 h) is shown, and the range of the operating conditions of the cell with self-control is determined. The power of the fuel cell at an efficiency of ～50% and the surface density of platinum on a cathode of ≈0.2 mg/cm² is 200–250 and 100 mW/cm² in the forced and natural air-convection modes, respectively, which is comparable with the advanced results.     

Humidity-independent portable air-hydrogen fuel cells with slotted silicon based gas-distributing plates

We have studied the characteristics of small-scale air-hydrogen fuel cells (FCs) operating in a free-breathing cathode regime. The cells are provided with a new gas-distributing element on the cathode side, which is based on a silicon plate with narrow through slots (slotted Si plate). It is shown that the use of a slotted Si plate significantly weakens the dependence of the FC characteristics on the humidity of environment in a broad temperature range. Indeed, at a fixed temperature, the FC power only changed within 10% when the relative humidity of the ambient air varied between 50 and 98%.     

The psychopathology of a depressive somato-autonomic symptom complex

The investigation is based on the hypothesis about psychopathological heterogeneity of the somatovegetative (biological) symptom complex of depression. To testify this statement the results of the analysis of the somatovegetative component of depressive syndrome in randomized selection (20 adult patients) were presented. Somatovegetative symptoms (disorders of sleep and appetite mainly) defined the pattern of debut and preceded manifestations of other signs of affective disorder in this group. Psychopathological qualification of disorders belonging to such symptom complex was presented as the phenomena of alienation of the most deep vital psychic functions, exactly somato-vegetative drives. The main psychopathological statements were argued by the data about dynamics of such states, which were followed by transformation into typical vital depressions. The results obtained were interpreted in accordance with traditional K. Schneider's conception of "depression without depression".     

Optimization of polyelectrolyte-based membrane-electrode assemblies for fuel cells

Dependence of the specific power of a hydrogen fuel cell (FC) on various factors involved in the fabrication of membrane-electrode assemblies (MEAs) based on polyelectrolyte membranes has been studied. The MEA technology has been optimized with respect to the following parameters determining the FC structure and characteristics: weight fractions of the Pt/C catalyst powder and carbon nanotubes (CNTs), content of polymer solution, and polymer type (Nafion 212, MF4-SK). MEAs with specific powers above 210 mW/cm² are obtained for air-hydrogen FCs operating at room temperature and nearly atmospheric hydrogen pressure.     

Investigation of catalytic activity of hydrides in the desulphurisation reactions of liquid hydrocarbon fuels

The sulphur content of liquid hydrocarbon fuels is an important index if their quality. The hydrides of Ni-Zr alloys are prospective catalysts for oil-product hydrodesulphurisation. They allow a higher degree of fuel purification from sulphur and they increase the equipment productivity.Test samples of the catalysts capsulate contacts are received and a method is developed for this process. Their catalytic activity both using the example of the demercaptanization reaction and the extraction of total sulphur from the kerosene fraction is studied. The processes occurring on Ni-Zr alloys due to the interaction with hydrogen are investigated by electron microscopy.     

Portable power source based on air-hydrogen fuel cells with free-breathing cathodes

Portable power source based on air-hydrogen fuel cells (FCs) operating in a free-breathing cathode regime has been developed. At a volume of 100 cm³, the source has a power capacity of 8.5 W h and generates a power of 2 W that is independent of the temperature within 5–40°C and the relative humidity of the ambient air within 40–98%. With respect to the specific energy characteristics, the proposed PTI type device exceeds other air-hydrogen FCs and in some respects is even superior to power sources based on air-methanol FCs.     

Melt texturing and properties control of Nd1+yBa2-yCu3Ox bulk materials

Melt textured NdBaCuO samples with T_c = 94 K and j_c(0 T, 77 K) = 46 kA/cm² have been prepared on an isothermal route. The thermodynamic background of this procedure which aims at the production of a Ba rich Nd-123 is pointed out.     

Modeling of corrosion product migration in the secondary circuit of nuclear power plants with WWER-1200

Models of corrosion and mass transfer of corrosion products in the pipes of the condensate-feeding and steam paths of the secondary circuit of NPPs with WWER-1200 are presented. The mass transfer and distribution of corrosion products over the currents of the working medium of the secondary circuit were calculated using the physicochemical model of mass transfer of corrosion products in which the secondary circuit is regarded as a cyclic system consisting of a number of interrelated elements. The circuit was divided into calculated regions in which the change in the parameters (flow rate, temperature, and pressure) was traced and the rates of corrosion and corrosion products entrainment, high-temperature рН, and iron concentration were calculated. The models were verified according to the results of chemical analyses at Kalinin NPP and iron corrosion product concentrations in the feed water at different NPPs depending on рН at 25°С (рН₂₅) for service times τ ≥ 5000 h. The calculated рН values at a coolant temperature t (рН_t) in the secondary circuit of NPPs with WWER-1200 were presented. The calculation of the distribution of рН_t and ethanolamine and ammonia concentrations over the condensate feed (CFC) and steam circuits is given. The models are designed for developing the calculation codes. The project solutions of ATOMPROEKT satisfy the safety and reliability requirements for power plants with WWER-1200. The calculated corrosion and corrosion product mass transfer parameters showed that the model allows the designer to choose between the increase of the correcting reagent concentration, the use of steel with higher chromium contents, and intermittent washing of the steam generator from sediments as the best solution for definite regions of the circuit.