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Item type:Publication, Access status: with files , Functionalization of carbon electrodes with nanotitania by atomic layer deposition(Hindawi Publishing Corporation, 2022-10-12); ; ; ; Carbon fibers are materials with a very high surface area and are interesting for applications such as filters, fire-resistant heat insulation, photocatalysis, and capacitor electrodes. Moreover, thermal burnout can easily remove these fibers, making them ideal templates for high-precision coatings or keeping them within the coated structure, generating nanostructured composites. In this work, two different substrates, carbon felt and bacterial nanocellulose were coated by TiO2 with atomic layer deposition (ALD). After deposition, the templates were pyrolyzed or further removed by burnout in the air. The microstructure evolution of the 3D interlocked-fibers structures was characterized by scanning electron microscopy and nitrogen adsorption surface area after each step. Stable anatase was present as a single TiO2 phase even after heat treatment at 800°C. Moreover, electrochemical impedance spectroscopy and constant current charge-discharge were employed to investigate the electrochemical properties of the samples. Our results show that all samples display a uniform layer after ALD and that the surface area decreases with an increasing number of ALD cycles. After burnout, the 3D structures presented a straw-like appearance to the shells. Nonetheless, both samples presented a power density comparable to a porous NiO/C, with the pyrolyzed bacterial nanocellulose sample displaying a higher pseudocapacitance performance than the carbon-felt samples.Publicationtype: Journal Article60 104 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Evaluation of permeability of ceramic wick structures for two phase heat transfer devicesThis work reports on different approaches to predict the pressure drop in capillary structures for two phase heat transfer devices (TPHTD). For this purpose, several porous wick structures were produced by slip casting and characterized concerning their porosity, critical pore diameter, capillary pressure and permeability. The wick structures exhibited porosity in the range of 48-58%, pore diameter ranging from 1 μm to 4 μm, with capillary pressure of 80 and 22 kPa, respectively. Two expressions were developed to simulate the pressure drop permeabilities as a function of the heat load applied to the TPHTD evaporator. The prime target of this work is to evaluate the differences in predicting pressure drop just by using the Darcyan constant, k1, and both by using Darcyan and non-Darcyan constant, k1 and k2. When k1 was used only it was considered as Darcyan approach and when both constants were taken into account it was considered as Forchheimer approach. Additionally, ceramic wick structures have been tested as capillary evaporator in a TPHTD. The startup was successful after 20 min the inlet and outlet evaporator temperatures remain constant. It confirms that all applied heat load was transported to the condenser.Publicationtype: Journal Article6