개질기용 예혼합 버너의 화염형태 및 안정성 특성

이필형(Pil Hyong Lee),박봉일(Bong Il Park),조순혜(Soon Hye Jo),황상순(Sang Soon Hwang) 한국연소학회 2010 한국연소학회지 Vol.15 No.3

Fuel processing systems which convert fuel into rich gas (such as stream reforming, partial oxidation, autothermal reforming) need high temperature environment (600~1,000℃). Generally, anode-off gas or mixture of anode-off gas and LNG is used as input gas of fuel reformer. In order to make efficient and low emission burner system for fuel reformer, it is necessary to elucidate the combustion and emission characteristic of fuel reformer burner. The purpose of this study is to develop a porous premixed flat ceramic burner that can be used for 1~5 ㎾ fuel cell reformer. Ceramic burner experiments using natural gas, hydrogen gas, anode off gas, mixture of natural gas & anode off gas were carried out respectively to investigate the flame characteristics by heating capacity and equivalence ratio. Results show that the stable flat flames can be established for natural gas, hydrogen gas, anode off gas and mixture of natural gas & anode off gas as reformer fuel in the porous ceramic burner. For all of fuels, their burning velocities become smaller as the equivalence ratio goes to the lean mixture ratio, and a lift-off occurs at lean limit. Flame length in hydrogen and anode off gas became longer with increasing the heat capacity. In particular, the blue surface flame is found to be very stable at a very lean equivalence ratio at heat capacity and different fuels. The exhausted NOx and CO measurement shows that the blue surface flame represents the lowest NOx and CO emissions since it remains very stable at a lean equivalence ratio.

In Situ Surface Modification of Ni-YSZ with BaZrO₃ for Enhancing the Sulfur Tolerance of Ni-YSZ Anode

Kwon, Ohhun,Sengodan, Sivaprakash,Lim, Chaehyun,Jeong, Hu Young,Shin, Jeeyoung,Ju, Young-Wan,Kim, Guntae The Electrochemical Society 2016 Journal of the Electrochemical Society Vol.163 No.9

<P>In this work, we report on a BaZrO3 (BZO) modified NiO-YSZ anode fabricated by co-sintering of NiO-YSZ and BaCO3 for SOFCs. The BZO modified Ni-YSZ anode shows stable electrochemical performance in H-2 fuel containing a high level of 100 ppm sulfur for more than 100 hours. On the other hand, an unmodified Ni-YSZ anode degrades significantly in 100 ppm sulfur containing H-2 fuel. The obtained results demonstrate that the BZO in the Ni-YSZ is an excellent catalyst for enhancing the sulfur tolerance of the conventional Ni-YSZ anode. Moreover, the surface modification strategy is simple and cost-effective, and thereby can promote commercialization of Ni-YSZ anode supported cells. (C) 2016 The Electrochemical Society. All rights reserved.</P>

Ni-(Ce_0.8-xTi_x)Sm_0.2O_2-δ anode for low temperature solid oxide fuel cells running on dry methane fuel

Han, Bing,Zhao, Kai,Hou, Xiaoxue,Kim, Dong-Jin,Kim, Bok-Hee,Ha, Su,Norton, M. Grant,Xu, Qing,Ahn, Byung-Guk Elsevier 2017 Journal of Power Sources Vol.338 No.-

<P><B>Abstract</B></P> <P>A titanium-doped Ce<SUB>0.8</SUB>Sm<SUB>0.2</SUB>O<SUB>1.9</SUB> composite is developed as an anode component of low temperature solid oxide fuel cells running on methane fuel. Crystallographic parameters of (Ce<SUB>0.8-x</SUB>Ti<SUB>x</SUB>)Sm<SUB>0.2</SUB>O<SUB>2-δ</SUB> (0.00 < x < 0.10) are investigated with respect to the amount of titanium. The composites show a single cubic phase with the titanium amount being in the range of 0.00–0.07, while the lattice parameters decrease with increasing titanium content. The (Ce<SUB>0.8-x</SUB>Ti<SUB>x</SUB>)Sm<SUB>0.2</SUB>O<SUB>2-δ</SUB> composites are applied to an anode-supported single cell consisting of Ni-(Ce<SUB>0.8-x</SUB>Ti<SUB>x</SUB>)Sm<SUB>0.2</SUB>O<SUB>2-δ</SUB> anode/Ce<SUB>0.8</SUB>Sm<SUB>0.2</SUB>O<SUB>1.9</SUB> electrolyte/La<SUB>0.6</SUB>Sr<SUB>0.4</SUB>Co<SUB>0.2</SUB>Fe<SUB>0.8</SUB>O<SUB>3-δ</SUB> cathode. Catalytic properties of Ni-(Ce<SUB>0.8-x</SUB>Ti<SUB>x</SUB>)Sm<SUB>0.2</SUB>O<SUB>2-δ</SUB> are inspected with the electrochemical performance and performance stability of the cells in dry methane fuel. The cell with Ni-(Ce<SUB>0.73</SUB>Ti<SUB>0.07</SUB>)Sm<SUB>0.2</SUB>O<SUB>2-δ</SUB> (x = 0.07) anode displays a low polarization resistance and an optimum maximum power density (679 mW cm<SUP>−2</SUP> at 600 °C). A performance stability investigation indicates that the cell exhibits a fairly low degradation rate of 3 mV h<SUP>−1</SUP> during a 31 h operation in dry methane. These findings suggest the application potential of the titanium doped Ce<SUB>0.8</SUB>Sm<SUB>0.2</SUB>O<SUB>1.9</SUB> for the anode of solid oxide fuel cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ti doped Ce<SUB>0.8</SUB>Sm<SUB>0.2</SUB>O<SUB>1.9</SUB> is found to be a potential anode material. </LI> <LI> Ni-(Ce<SUB>0.8-x</SUB>Ti<SUB>x</SUB>)Sm<SUB>0.2</SUB>O<SUB>2-δ</SUB> shows excellent electrochemical performance in methane. </LI> <LI> Good performance stability demonstrates application feasibility of the anode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Simultaneous A- and B- site substituted double perovskite (AA’B₂O_5+<i>δ</i>) as a new high-performance and redox-stable anode material for solid oxide fuel cells

Lee, Daae,Kim, Dongyoung,Son, Seung Jae,Kwon, Young-il,Lee, Younki,Ahn, Jou-Hyeon,Joo, Jong Hoon Elsevier 2019 Journal of Power Sources Vol.434 No.-

<P><B>Abstract</B></P> <P>In this study, a novel PrBa<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Fe<SUB>2-x</SUB>Ge<SUB>x</SUB>O<SUB>5+δ</SUB> (PBSFG) double perovskite is first introduced by the co-substitution of Sr for A-sites and Ge for B-sites as a high-performance and redox-stable anode material for solid oxide fuel cells. The modification of the A-sites of PrBaFe<SUB>2</SUB>O<SUB>5+<I>δ</I> </SUB> by Sr-doping (PBSF) significantly enhances electrical conductivity of PBSF under a reducing atmosphere by several orders of magnitude at 800 °C. Subsequently, Ge-doping on B-sites leads to meaningful increases in oxygen ion conductivity of PBSFG, and is owing to increases in the oxygen vacancy concentration. The electrochemical performances of PBSFG-Ce<SUB>0.9</SUB>Gd<SUB>0.1</SUB>O<SUB>2-δ</SUB> (GDC) are evaluated using a composite anode with a GDC|Zr<SUB>0.79</SUB>Sc<SUB>0.2</SUB>Ce<SUB>0.01</SUB>O<SUB>2-δ</SUB> (ScSZ)|GDC electrolyte (~100 μm) and a La<SUB>0.6</SUB>Sr<SUB>0.4</SUB>Co<SUB>0.2</SUB>Fe<SUB>0.8</SUB>O<SUB>3-<I>δ</I> </SUB> (LSCF) cathode. The cell shows critical improvement in the maximum power density (838.4 mW cm<SUP>−2</SUP> at 800 °C) relative to the PrBaFe<SUB>2</SUB>O<SUB>5+<I>δ</I> </SUB> composite (497.6 mW cm<SUP>−2</SUP>). Moreover, it shows good redox-cycle stability from fuel to air under a current load.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Simultaneous A- and B-site doped double perovskite is proposed as a new SOFC anode. </LI> <LI> Electrical conductivity is enhanced by A-site modification by Sr doping. </LI> <LI> Oxygen diffusivity is meaningfully improved by B-site modification by Ge doping. </LI> <LI> The anode shows high performance and excellent redox cycle stability. </LI> </UL> </P>

Analysis of Peel Strength of Consisting of an Aluminum Sheet, Anodic Aluminum Oxide and a Copper Foil Laminate Composite

신형원,이효수,정승부 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.1

Laminate composites consisting of an aluminum sheet, anodic aluminum oxide, and copper foil have been used as heat-spreader materials for high-power light-emitting diodes (LEDs). These composites are comparable to the conventional structure comprising an aluminum sheet, epoxy adhesives, and copper foil. The peel strength between the copper foil and anodic aluminum oxide should be more than 1.0 kgf/cm in order to be applied in high-power LED products. We investigated the effect of the anodic aluminum oxide morphology and heattreatment conditions on the peel strength of the composites. We formed an anodic aluminum oxide layer on a 99.999% pure aluminum sheet using electrochemical anodization. A Ti/Cu seed layer was formed using the sputtering direct bonding copper process in order to form a copper circuit layer on the anodic aluminum oxide layer by electroplating. The developed heat spreader, composed of an aluminum layer, anodic aluminum oxide, and a copper circuit layer, showed peel strengths ranging from 1.05 to 3.45 kgf/cm, which is very suitable for high-power LED applications.

Metal PCB에 있어서 양극산화법으로 제작한 Al₂O₃ 절연막의 방열특성

조재승(Jae-Seung Jo),김정호(Jeong-Ho Kim),고상원(Sang-Won Ko),임실묵(Sil-Mook Lim) 한국표면공학회 2015 한국표면공학회지 Vol.48 No.2

High efficiency LED device is being concerned due to its high heat loss, and such heat loss will cause a shorter lifespan and lower efficiency. Since there is a demand for the materials that can release heat quickly into the external air, the organic insulating layer was required to be replaced with high thermal conductive materials such as metal or ceramics. Through anodizing the upper layer of Al, the Breakdown Voltage of 3kV was obtained by using an uniform thickness of 60 μm aluminum oxide(Al₂O₃) and was carried out to determine the optimum process conditions when thermal cracking does not occur. Two Ni layers were formed above the layer of Al₂O₃ by sputtering deposition and electroplating process, and saccharin was added for the purpose of minimizing the remain stress in electroplating process. The results presented that the 3-layer film including the Ni layer has an adhesive force of 10N and the thermal conductivity for heat dissipation is achieved by 150W/mK level, and leads to improvement about 7 times or above in thermal conductivity, as opposed to the organic insulation layer.

Fabrication of Plasma Electrolytic Oxidation Coatings on Magnesium AZ91D Casting Alloys

Sung-Hyung Lee,Hitoshi Yashiro,Song-Zhu Kure-Chu 한국표면공학회 2017 한국표면공학회지 Vol.50 No.6

AZ91D casting alloy requires an advanced plasma anodizing processing because large amount of defects are liable to generate during anodization. In this study, plasma electrolytic oxidation (PEO) of AZ91D Mg alloy was conducted by the application of either constant voltage or current using a pulse mode and its effects on pore formation, surface roughness and corrosion resistance were investigated. The PEO films showed a three-layer structure. The PEO film thickness was found to increase linearly with voltage. The surface roughness, Ra, ranged between 0.2 μm and 0.3 μm. The corrosion resistance increased from RN 3.5 to 9.5 by the PEO treatment when evaluated according to the 72 hour salt spray test. The PEO-treated surface exhibited higher pitting potential than the raw material

Anode processes on Pt and ceramic anodes in chloride and oxide-chloride melts

A.R. Mullabaev,V.A. Kovrov,A.S. Kholkina,Yu.P. Zaikov 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3

Platinum anodes are widely used for metal oxides reduction in LiCleLi2O, however high-cost and lowcorrosionresistance hinder their implementation. NiOeLi2O ceramics is an alternative corrosion resistantanode material. Anode processes on platinum and NiOeLi2O ceramics were studied in (80 mol.%)LiCl-(20mol.%)KCl and (80 mol.%)LiCl-(20 mol.%)KCleLi2O melts by cyclic voltammetry, potentiostatic andgalvanostatic electrolysis. Experiments performed in the LiCleKCl melt without Li2O illustrate that a Ptanode dissolution causes the Pt2þ ions formation at 3.14 V and 550 С and at 3.04 V and 650оС. A twostagePt oxidation was observed in the melts with the Li2O at 2.40 ÷ 2.43 V, which resulted in theLi2PtO3 formation. Oxygen current efficiency of the Pt anode at 2.8 V and 650 С reached about 96%. Theanode process on the NiOeLi2O electrode in the LiCleKCl melt without Li2O proceeds at the potentialsmore positive than 3.1 V and results in the electrochemical decomposition of ceramic electrode to NiOand O2. Oxygen current efficiency on NiOeLi2O is close to 100%. The NiOeLi2O ceramic anode demonstratedgood electrochemical characteristics during the galvanostatic electrolysis at 0.25 A/cm2 for 35 hand may be successfully used for pyrochemical treating of spent nuclear fuel.

Catalytic Effects of Barium Carbonate on the Anodic Performance of Solid Oxide Fuel Cells

Yoon, Sung-Eun,Ahn, Jae-Yeong,Park, Jong-Sung The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.5

To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

Fabrication of NiO-Y:BaZrO₃ Composite Anode for Thin Film-Protonic Ceramic Fuel Cells using Tape-Casting

Bae, Kiho,Noh, Ho-Sung,Jang, Dong Young,Kim, Manjin,Kim, Hyun Joong,Hong, Jongsup,Lee, Jong-Ho,Kim, Byung-Kook,Son, Ji-Won,Shim, Joon Hyung The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.5

Optimization of the fabrication process of NiO-yttrium doped barium zirconate (BZY) composite anode substrates using tape-casting for high performance thin-film protonic ceramic fuel cells (PCFCs) is investigated. The anode substrate is composed of a tens of microns-thick anode functional layer laminated over a porous anode substrate. The macro-pore structure of the anode support is induced by micron-scale polymethyl methacrylate (PMMA) pore formers. Thermal gravity analysis (TGA) and a dilatometer are used to determine the polymeric additive burn-out and sintering temperatures. Crystallinity and microstructure of the tape-cast NiO-BZY anode are analyzed after the sintering.