2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 9: Molten Salts and Ionic Liquids, Energy Production
| Editors: | Kongoli F, Gaune-Escard M, Turna T, Mauntz M, Dodds H.L. |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 390 pages |
| ISBN: | 978-1-987820-24-9 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Wettability of Molten Carbonate Fuel Cell Materials
Liangjuan Gao1; Robert Selman2; Philip Nash3;1ILLINOIS INSTITUTE OF TECHNOLOGY, Chicago, United States; 2, Chicago, United States; 3IIT, Chicago, United States;
Type of Paper: Regular
Id Paper: 181
Topic: 13
Abstract:
The wettability of molten carbonate fuel cell materials by molten carbonate mixtures under MCFC operating conditions was studied by means of the sessile drop method using an optical instrumental system. Observations were made of the melting and spreading of a solid carbonate pellet upon controlled temperature increase, under either a reducing atmosphere (80%H2/20%CO2 humidified at 45oC) or pure CO2. The mass of the carbonate pellet was found to have an effect on the development of the contact angle on dense and smooth Ni foil (purity 99.5%) under a reducing atmosphere. The contact angle showed a significant decrease (suggesting increased wettability) when the mass of the carbonate decreased below a certain weight. This appeared to be correlated with the generation of gas bubbles at the interface which decreased the effective contact of solid Ni surface with the liquid carbonate. It was observed that large bubbles were generated under reducing atmosphere, which disappeared quickly when the gas atmosphere was changed to the pure CO2 atmosphere. On the contrary, small bubbles were generated but disappeared quickly and spontaneously during the melting and wetting of the carbonate on a solid smooth Ni surface under pure CO2 atmosphere, while large bubbles reappeared at the interface of the solid Ni surface and liquid carbonate after switching to the reducing gas. We infer from this that the water gas shift equilibrium CO2+H2=CO+H2O (1)
is established very rapidly at the scale of individual droplets or films of molten carbonate on nickel, and leads to gas bubble formation due to the very different levels of solubility of H2, CO, and CO2 in molten carbonate. To determine the effect of porosity of the anode on the wetting by molten carbonate, spreading and absorption of carbonate by potential Ni-Al alloy anode substrate with porosity of 25-35% was tested using carbonate pellets of various mass.
Keywords:
Wettability;Molten carbonate; Contact angle;Interface;References:
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