Zbigniew Magonski

A ceramic mini system for the detection of hydrocarbon radicals

This paper presents two components of a ceramic analytical system—a capillary column and a flame ionization detector designed and produced using photoimageable thick-film dielectric Fodel QM44F combined with a low temperature cofired ceramic tape. The microfluidic components are integrated onto a single piece of alumina substrate, dimensions 65 × 50 mm2, and have incorporated into them thick-film platinum heaters which ensure temperature control. The ceramic analytical minisystem is intended to detect—on the basis of ion current measurements—the presence of hydrocarbons in the analyte being passed through the capillary column and burned in the combustion cavity of the flame ionization detector. Ionic current in the range of nA was detected after introducing the analytes into the separation column.

Stack of Planar Double-Sided Solid Oxide Fuel Cells

A new design of a small power SOFC battery is presented. The battery consists of an array of flat double-sided fuel cells assembled with only two screws. Fuel cells are made with the application of commercially available HTCC green tapes. Eight layers of 180μm thick anode tape (YSZ+NiO) constitute the anode base structure of the double-sided fuel cell. Within the anode base structure, the separate areas serve as: the functional anode, the anode current collector, and the support for the anode functional layer. Also a network of fine micro channels is embedded within the anode base structure. The individual double-sided fuel cell is completed by deposition of the following layers, which constitute the electrolyte, the cathode, and the cathode current collector These layers are deposited on both sides of the anode base structure by means of screen-printing. Each double-sided fuel cell is provided with the own separate fuel distributor and combustion product collector. That beneficial feature enables complet...

Stack of solid oxide fuel cells

Purpose – The paper aims to present the innovative design of a planar multilayered high temperature solid oxide fuel cell (SOFC), which is easy to manufacture, and features high resistance to rapid temperature changes. Temperature resistance was accomplished thanks to easy to heat, thin flat ceramic structure of the cell and elimination of metallic interconnections. Design/methodology/approach – The ceramic fuel cell consists of the anode core made of six to eight layers of nickel/yttria-stabilized zirconia tapes (Ni/YSZ) isostatically pressed into a laminate. Two networks of fuel distribution microchannels are engraved on both sides of the anode laminate. The microchannels are subsequently covered with a thin layer of the functional anode tape made of Ni/YSZ and a solid electrolyte tape made of YSZ. Findings – The single planar double-sided ceramic SOFC of dimensions 19 × 60 × 1.2 mm3 provides 3.2 Watts of electric power. The prototype of the battery which consists of four SOFCs provides an output power ...

Photoimageable Thick-Film Components for a Ceramic Analytical Microsystem

This paper presents ceramic microfluidic components—a meander capillary column and a flame ionization detector—which have been designed and fabricated using photoimageable thick-film dielectric Fodel QM44F combined with low-temperature cofired ceramic tape. The components are integrated on a single piece of alumina substrate of dimensions 65 × 50 mm and have incorporated thick-film platinum heaters to ensure their temperature control. Details of the technological process as well as the application set-up for the tested components are presented. The samples of analyte were detected by a flame ionization detector after passage through a capillary column.

New proposal to the electrical representation of a solid oxide fuel cell

Purpose The aim of this paper is to find the electrical representation of a solid oxide fuel cell (SOFC) that enables the application of typical exploitation characteristics of fuel cells for estimation of fuel cell parameters (for example, exchange current) and easy analysis of phenomena occurred during the fuel cell operation. Design/methodology/approach Three-layer structure of an SOFC, where a thin semi-conducting layer of electrolyte separates the anode from the cathode, shows a strong similarity to typical semiconductor devices built on the basis of P-N junctions, like diodes or transistors. Current–voltage (I-V) characteristics of a fuel cell can be described by the same mathematical functions as I-V plots of semiconductor devices. On the basis of this similarity and analysis of impedance spectra of a real fuel cell, two electrical representations of the SOFC have been created. Findings The simplified electrical representation of SOFC consists of a voltage source connected in series with a diode, which symbolizes a voltage drop on a cell cathode, and two resistors. This model is based on the similarity of Butler-Volmer to Shockley equation. The advanced representation comprises a voltage source connected in series with a bipolar transistor in close to saturation mode and two resistors. The base-emitter junction of the transistor represents voltage drop on the cell cathode, and the base-collector junction represents voltage drop on the cell anode. This model is based on the similarity of Butler-Volmer equation to Ebers-Moll equation. Originality/value The proposed approach based on the Shockley and Ebers-Moll formulas enables the more accurate estimation of the ion exchange current and other fuel cell parameters than the approach based on the Butler-Volmer and Tafel formulas. The usability of semiconductor models for analysis of SOFC operation was proved. The models were successively applied in a new design of a planar ceramic fuel cell, which features by reduced thermal capacity, short start-up time and limited number of metal components and which has become the basis for the SOFC stack design.

New approach to the electrical representation of SOFC

Three layer structure of Solid Oxide Fuel Cell (SOFC), where a thin semi-conducting layer of electrolyte separates the anode from the cathode, shows a strong similarity to typical semiconductor devices built on the basis of P-N junctions, like diodes or transistors. On the basis of this similarity, the attempt of application of Shockley’s formula for the expression of a current-voltage relation of SOFC is presented. The proposed approach enables a more accurate estimation of the ion exchange current, than the approach based on the Tafel’s formula.

Embossing in fuel cell fabrication

Purpose – The purpose of this paper is to present the embossing as a replication technique for structuring fuel channels in the anode-supported solid oxide fuel cells (SOFCs). Design/methodology/approach – The anode laminate, which was exposed to embossing, consisted of eight layers of isostatic pressed Ni-yttria-stabilized zirconia tapes (Ni-YSZ). Preheating the mould and soaking the laminate in the plasticizer was applied before structuring of the channels to soften the laminate. Compressing tests were carried out to investigate the embossing ability of the Ni-YSZ laminate and to find the optimal processing parameters. Embossing was carried out with a testing machine, and the samples were exposed to embossing forces in the range up 20 kN with a certain speed of compression and a dwell time. Findings – The embossing parameters (force of compression, speed of compression and dwell time) suitable for proper fuel channels formation were established. Shapes, profiles and dimensions of the embossed channels w...