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Bai Y.,South China University of Technology | Liu Y.,South China University of Technology | Tang Y.,South China University of Technology | Xie Y.,South China University of Technology | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2011

Tubular cone-shaped Ni-based anode-supported solid oxide fuel cells (SOFCs), with yttria-stabilized zirconia (YSZ) electrolyte and La 0.8Sr 0.2MnO 3 (LSM) cathode, were investigated with Fe catalyst-loaded activated carbon directly filled in as fuel. Three identical single cells were operated at different current and it turned out that larger current resulted in shorter operation life and smaller carbon utilization. A 3-cell-stack, with the segmented cone-shaped cells connected in series, was assembled and tested. A peak power density of 465 mW cm -2 and a volumetric power density of 710 mW cm -3 were achieved at 850 °C. The degradation performance was analyzed according to the electrochemical characterization and SEM-EDX measurement. Based on the experimental results, the potential of developing such direct carbon SOFC into a high performance battery was proposed. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Zhang G.,Beijing University of Technology | Liu Z.,Key Laboratory of Enhanced Heat Transfer and Energy Conservation | Liu Z.,Beijing University of Technology | Wang C.,Beijing University of Technology
International Journal of Heat and Mass Transfer | Year: 2014

A visualization study of boiling and condensation co-existing phase change heat transfer in a small confined space is conducted with de-ionized water as the working medium. The confined space is a closed chamber that consists of a heating copper rod (40 mm in diameter) whose top end is used as boiling surface, a cooling copper block whose bottom end (40 mm in diameter) is used as condensing surface and a circular quartz glass tube. The spacing between the boiling and the condensation surface is 33 mm, water layer thickness in the chamber is set at 9 mm, 12 mm, 15 mm, 18 mm, 21 mm and 24 mm, respectively. Experimental observation and results show that, at the covered heat flux region (4.6 × 104 W/m2-9.7 × 104 W/m 2) in this paper, the boiling and condensation processes have strong interactions over each other and there always exist an optimum liquid level at which both boiling and condensation heat transfer coefficients acquired their maximum values. Typical images and possible explanations for the heat transfer characteristics of different water layer thicknesses are presented and it is disclosed that the heat transfer performance is strongly related to the interaction between boiling and condensation. Some peculiar phenomena are reported of the bubble behavior and boiling-condensation interactions. © 2014 Elsevier Ltd. All rights reserved. Source


Liu Y.,South China University of Technology | Bai Y.,South China University of Technology | Liu J.,South China University of Technology | Liu J.,Key Laboratory of Enhanced Heat Transfer and Energy Conservation | Liu J.,Key Laboratory of New Energy Technology for Guangdong Universities
Journal of Power Sources | Year: 2011

(Ni 0.75Fe 0.25-xMgO)/YSZ samples - with a varying weight percentage x (0, 5%, 10%) of MgO with respect to Ni 0.75Fe 0.25 - were prepared and studied as anodes for intermediate temperature solid oxide fuel cells (SOFCs) operated on humidified methane (3% H 2O). Among the cells with different anode compositions, it was found that the cell with the (Ni 0.75Fe 0.25-5%MgO)/YSZ anode showed the highest power density, giving 648 mW cm -2 at 800 °C. The cells with MgO-doped anodes were able to operate stably for 20 h under a current density of 0.53 A cm -2 at 700 °C without observed degradation, while the cells without MgO degraded rapidly. The mechanisms responsible for the superior performance and duration of the (Ni 0.75Fe 0.25-5%MgO)/YSZ anode were analyzed. © 2011 Elsevier B.V. All rights reserved. Source


Huang W.,South China University of Technology | Zhou X.,South China University of Technology | Xia Q.,Key Laboratory of Enhanced Heat Transfer and Energy Conservation | Peng J.,South China University of Technology | And 2 more authors.
Industrial and Engineering Chemistry Research | Year: 2014

Composites (GrO@Cu-BTC) based on Cu-BTC and graphene oxide were synthesized by a solvothermal method for the separation of CO2/CH4 binary mixtures. The as-synthesized composites were then characterized. The isotherms of CO2 and CH4 on the as-synthesized materials were measured by the volumetric method. The isotherms and adsorption selectivities of CO2/CH4 binary mixtures were estimated on the basis of ideal adsorbed solution theory (IAST). The results showed that the composite 1GrO@Cu-BTC had a higher BET surface area and pore volume compared to the parent Cu-BTC. More importantly, its adsorption capacity for CO2 improved significantly in comparison with that of Cu-BTC, which was up to 8.19 mmol/g at 1 bar and 273 K. The dual-site Langmuir-Freundlich (DSLF) model was applied favorably for fitting experimental isotherm data of CO2 and CH4 adsorption on the samples. The predicted isotherms of the binary mixture based on IAST showed that CO2 was more favorably adsorbed than CH4 on the sample 1GrO@Cu-BTC. TPD showed that the desorption activation energy of CO2 on 1GrO@Cu-BTC was higher than that on Cu-BTC, indicating a stronger interaction between CO2 molecules and 1GrO@Cu-BTC. Thus, the CO2/CH4 adsorption selectivity of the composite 1GrO@Cu-BTC was significantly higher than that of Cu-BTC, namely, 14 at 1 bar, or 2.6 times that of Cu-BTC. © 2014 American Chemical Society. Source


Wang H.,South China University of Technology | Liu J.,South China University of Technology | Liu J.,Key Laboratory of Enhanced Heat Transfer and Energy Conservation | Liu J.,Key Laboratory of Fuel Cell Technology of Guangdong Province
International Journal of Hydrogen Energy | Year: 2012

Anode-supported cone-shaped tubular solid oxide fuel cells (SOFCs) are successfully fabricated by a phase inversion method. During processing, the two opposite sides of each cone-shaped anode tube are in different conditions - one side is in contact with coagulant (the corresponding surface is named as "W-surface"), while the other is isolated from coagulate (I-surface). Single SOFCs are made with YSZ electrolyte membrane coated on either W-surface or I-surface. Compared to the cell with YSZ membrane on W-surface, the cell on I-surface exhibits better performance, giving a maximum power density of 350 mW cm-2 at 800°C, using wet hydrogen as fuel and ambient air as oxidant. AC impedance test results are consistent with the performance. The sectional and surface structures of the SOFCs were examined by SEM and the relationship between SOFC performance and anode structure is analyzed. Structure of anodes fabricated at different phase inversion temperature is also investigated. Copyright © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

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