A new approach to understand liquid injection into atmospheric plasma jets

Infrared images are used to characterize the atmospheric plasma and the influence of liquid injection into it. In the infrared spectral range low energies of rotational vibrational transitions can be captured which are emitted by hot liquid vapors. These vapor streams enable the qualification of the injection depth. High speed shadowgraphy is used to prove the correlations between vapor cloud and drop atomization behavior. In addition the combustion of organic liquids like ethanol and pentanol can be seen directly with an increase of emitted radiation. A direct correlation between vapor cone and liquid properties can be made. Lower Ohnesorge numbers lead to more focused vapor beams

Recent Progress in Intermediate Temperature SOFCs (ITSOFCs) Development at DLR

Metal-supported ITSOFCs having NiO or NiO+YDC 15 anode, yttria stabilized ceria electrolyte (YDC 15) and LSCF or LSCF+CGO composite cathodes were fabricated via plasma spraying for operation in the temperature range of 600-700°C. Highest performance was recorded with NiO+YDC 15 / YDC 15 / LSCF+CGO cells. In the next step it is planned to optimize fabrication parameters in order to attain crack free and thinner electrolytes and more porous composite cathode which will lead to double cell performance

Improving stochiometery and processing of LSCF oxygen electrode for SOFC

New stochiometries of La1-xSrxCo0.2Fe0.8O3-ä (LSCF) for the oxygen electrode of SOFC were developed. The functional layers were manufactured by atmospheric plasma spraying (APS) using TriplexPro gun. Processing of LSCF was optimized for high gas permeability and low decomposition of the powder with focus on high production rates. Studies on microstructure using optical microscopy, scanning electron microscopy (SEM) and x-ray diffraction (XRD) were linked to plasma spray parameters. As a critical factor for decomposition the dwell time of the particles inside the plasma was identified. Functional layers had an improved porosity of about 20 vol%. At 800°C, power densities of above 640 mW/cm² at 0.7 V were recorded with H2/ai

Thermal Plasma Spraying Applied on Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs), attractive for diverse applications in a broad range from small portable and auxiliary power units, up to central power systems, are conventionally produced by sintering methods. However, plasma spraying promises some advantages particularly for cells with metal support. In the present paper, research activities conducted in recent years at DLR as well as latest developments on plasma sprayed functional layers for SOFC as cathodes, electrolytes, and anodes are reported. Power densities of more than 800 mW/cm2 were achieved for plasma sprayed single cells of 12.56 cm2 size, and 300 mW/cm2, respectively, with a 250 W stack made of 10 cells. These values were attained at 0.7 V and 800 °�C, with H2:N2 = 1:1 as fuel gas and air as oxidizing gas. Furthermore, continuous operation of more than 5000 h was attained with a plasma sprayed metal-supported SOFC stack which could also withstand more than 30 redox and thermal cycles

Impedance Behavior of LSCF/YDC/LSCF Symmetrical Half Cell Prepared by Plasma Spray

Impedance studies of electrolyte supported symmetrical half cells La0,6Sr0,4Co0,2Fe0,8O3- /Ce0,85Y0,15O2-/La0,6Sr0,4Co0,2Fe0,8O3- with electrodes deposited by atmospheric plasma spraying (APS) show that the applied technique influences reversibly the substrate properties, introducing additional contribution to the interface substrate/electrode. After thermal treatment in temperature range 100-800oC during the impedance measurements, an annealing effect is observed. It eliminates the additional increase of the electrolyte resistivity and increases slightly the polarization resistance. The observed effect could be related to thermally and/or mechanically induced local microstructure defects, caused by the APS procedure. The obtained results show that for stabilization of the cell’s performance, annealing should be performed after the APS deposition. It can be supposed that an appropriate annealing atmosphere may prevent the electrodes deactivation