The Effect of H2S on the Performance of SOFCs using Methane Containing Fuel

In recent years, the interest for using biogas derived from biomass as fuel in solid oxide fuel cells (SOFCs) has increased. To maximise the biogas to electrical energy output, it is important to study the effects of the main biogas components (CH₄ and CO₂), minor ones and traces (e.g. H₂S) on performance and durability of the SOFC. Single anode‐supported SOFCs with Ni–Yttria‐Stabilised‐Zirconia (YSZ) anodes, YSZ electrolytes and lanthanum‐strontium‐manganite (LSM)–YSZ cathodes have been tested with a CH₄–H₂O–H₂ fuel mixture at open circuit voltage (OCV) and 1 A cm^–2 current load (850 °C). The cell performance was monitored with electric measurements and impedance spectroscopy. At OCV 2–24 ppm H₂S were added to the fuel in 24 h intervals. The reforming activity of the Ni‐containing anode decreased rapidly when H₂S was added to the fuel. This ultimately resulted in a lower production of fuel (H₂ and CO) from CH₄. Applying 1 A cm^–2 current load, a maximum concentration of 7 ppm H₂S was acceptable for a 24 h period.     

Metal Matrix Composites Deposition in Twin Wire Arc Spraying Utilizing an External Powder Injection Composition

The powder injection parameters, the location of the injection port, as well as the metal matrix composites are important features, which determine the deposition efficiency and embedding behavior of hard materials in the surrounding matrix of the twin wire arc-spraying process. This study investigates the applicability of external powder injection and aims to determine whether the powder injection parameters, the location, and the material combination (composition of the matrix as well as hard material) need to be specifically tailored. Therefore, the position of the injection port in relation to the arc zone was altered along the spraying axis and perpendicular to the arc. The axial position of the injection port determines the thermal activation of the injected powder. An injection behind the arc, close to the nozzle outlet, seems to enhance the thermal activation. The optimal injection positions of different hard materials in combination with zinc-, nickel- and iron-based matrices were found to be closer to the arc zone utilizing a high-speed camera system. The powder size, the mass of the particle, the carrier gas flow, and the electric insulation of the hard material affect the perpendicular position of the radial injection port. These findings show that the local powder injection, the wetting behavior of particles in the realm of the molten pool as well as the atomization behavior of the molten pool all affect the embedding behavior of the hard material in the surrounded metallic matrix. Hardness measurement by means of nanoindentation and EDX analysis along transition zones were utilized to estimate the bonding strength. The observation of a diffusion zone indicates a strong metallurgical bonding for boron carbides embedded in steel matrix.     

Study of Internal and External Leaks in Tests of Anode‐Supported SOFCs

A planar anode‐supported solid oxide fuel cell (SOFC) has been tested to investigate gas tightness of the electrolyte and the applied seals. Gas leaks reduce the efficiency of the SOFC and it is thus important to determine and minimise them. Probe gases (He and Ar) and a Quadrupole Mass Spectrometer were used to detect both internal (through electrolyte) and external (through seals) gas leaks. The internal gas leak through the electrolyte was quantified under different conditions, as was the external leak from the surroundings to the anode. The internal gas leak did not depend on the pressure difference between the anode and the cathode gas compartment, and can thus be described as diffusion driven. External leaks between the surroundings and the anode, but not the cathode gas compartment was observed. They were influenced by the pressure difference and are thus driven by both concentration and pressure gradients. The measured gas leaks deduced from the probe gas experiments and the total leak calculated from the deviation between the Emf defined by the gases and the cell OCV (which contains all gas leaks as well as effects of electronic leaks) were compared. Good agreement between the two measures was observed.     

Katalysatorcharakterisierung mit O2‐TPD,N2‐ und Kr‐Gassorption sowie REM am Beispiel der Epoxidierung von 1,3‐Butadien

The temperature‐programmed O₂ desorption (O₂‐TPD), the N₂‐ and Kr‐ sorption as well as the scanning‐electron microscope (SEM) are important analysis methods in catalysis chemistry. By the example of a corundum and of a calcium hexaaluminate substrate the methods are used and the potential regarding to the surface properties and the activity of the assigned catalysts thereby pointed. Which of the two catalyst systems for the Ag‐catalyzed epoxidation of 1,3‐butadiene to 3,4‐epoxy‐1‐butene is more favorable is tested in a tubular reactor.     

RHEOLOGICAL BEHAVIOR OF CONCENTRATED INULIN SOLUTION: INFLUENCE OF SOLUBLE SOLIDS CONCENTRATION AND TEMPERATURE

Inulin is a storage polysaccharide present in more than 30,000 vegetable products, including chicory roots, that are considered suitable for industrial application. The objective of this work was to evaluate the influence of temperature and the soluble solids concentration on the rheological behavior of a concentrated inulin solution obtained from a centrifugation process from chicory roots, after freezing at − 24C. For all the evaluated soluble solids concentrations, inulin solutions showed a rheological behavior of a highly pseudoplastic fluid, with high resistance to flow at low strain rates followed by a breakdown of the structure when the shear rate increased. The effect of temperature on the apparent viscosity of inulin solutions can be represented by the Arrhenius equation. The rheological behavior of inulin solutions can be represented by the Herschel–Bulkley, Casson, Cross and Power Law equations, where the consistency index increases as temperature rises and the soluble solids concentration as well.

PRACTICAL APPLICATIONS

The main objective of this work was to analyze the rheological behavior of a concentrated inulin solution obtained from chicory roots, to check the possibility of its application to obtain powder inulin.
The concentrated inulin solution was obtained by diffusion in hot water, followed by concentration by evaporation and phase separation conducted by lowering the temperature (−24C) and centrifugation at a velocity of 10,000 rpm for a time interval of 15 min. However, this solution is still going to be processed. Therefore, it is important to know its rheological behavior.
The influence of temperature and the soluble solids concentration on the rheological behavior of the concentrated inulin solution was also studied.     

Commercial aircraft engine emissions characterization of in-use aircraft at Hartsfield-Jackson Atlanta International Airport

The emissions from in-use commercial aircraft engines have been analyzed for selected gas-phase species and particulate characteristics using continuous extractive sampling 1-2 min downwind from operational taxi- and runways at Hartsfield-Jackson Atlanta International Airport. Using the aircraft tail numbers, 376 plumes were associated with specific engine models. In general, for takeoff plumes, the measured NOx emission index is lower (approximately 18%) than that predicted by engine certification data corrected for ambient conditions. These results are an in-service observation of the practice of "reduced thrust takeoff". The CO emission index observed in ground idle plumes was greater (up to 100%) than predicted by engine certification data for the 7% thrust condition. Significant differences are observed in the emissions of black carbon and particle number among different engine models/technologies. The presence of a mode at approximately 65 nm (mobility diameter) associated with takeoff plumes and a smaller mode at approximately 25 nm associated with idle plumes has been observed. An anticorrelation between particle mass loading and particle number concentration is observed.     

CALCOFLUOR AS A FLUORESCENT PROBE TO DETECT BIOFILMS OF FOODBORNE PATHOGENS

Biofilms enable foodborne pathogens to resist removal from surfaces, survive disinfection and elude detection. This study evaluated the use of Calcofluor, which binds to polysaccharides containing β-D-glucans, to detect biofilms produced by Salmonella enterica serovar Berta and Salmonella enterica serovar Typhimurium DT104 (St DT104), Escherichia coli, Aeromonas hydrophila, Vibrio cholerae O139 and Hyphomonas adhaerens. Biofilms produced by St DT104, S. berta and V. cholerae on five types of surfaces (glass, polypropylene, Teflon™, stainless steel and aluminum) were detected by Calcofluor. Results suggest the potential use of Calcofluor as probes of foodborne pathogens in biofilms.     

Airborne high‐resolution images for grape classification: changes in correlation between technological and late maturity in a Sangiovese vineyard in Central Italy

Background and Aims: The goal of this study was to investigate the relationships between NDVI values at different phenological stages and measurements of grape parameters at two different harvest dates. Methods and Results: The research was done on a Sangiovese vineyard in Central Italy. Over four seasons, airborne NDVI measurements acquired between June and August were related to grape parameters (yield per vine, pH, °Brix, anthocyanins and polyphenols) at technological harvest (H1) and two weeks later (H2). Correlations were higher at H1 and decreased at H2 with a different rate depending on the parameter. °Brix and pH correlations showed a moderate rate of variation between H1 and H2; bigger differences and a different inter‐annual dynamic were observed in anthocyanins and polyphenols between H1 and H2. Conclusions: The ability of NDVI to discriminate different grape classes was confirmed, but its efficacy substantially varies depending on the harvest date. These results suggest the existence, within the same vineyard, of different grape populations having specific timing and shape of ripening curve; as a consequence, distinct vigour zones of the vineyard show a different evolution of the content of grape parameters between the two harvests thus influencing the degree of correlation between grape quality and NDVI measurements. Significance of the Study: This is the first study in which harvest date has been considered for its influence on the predictive skill of RS. It therefore highlights not only the importance of spatial variation within the single vineyard, but also the importance of ripening dynamics.