| 1. |
- Wang, Nan, 1988, et al.
(författare)
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Tailoring the Thermal and Mechanical Properties of Graphene Film by Structural Engineering
- 2018
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 14:29
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Tidskriftsartikel (refereegranskat)abstract
- Due to substantial phonon scattering induced by various structural defects, the in-plane thermal conductivity (K) of graphene films (GFs) is still inferior to the commercial pyrolytic graphite sheet (PGS). Here, the problem is solved by engineering the structures of GFs in the aspects of grain size, film alignment, and thickness, and interlayer binding energy. The maximum K of GFs reaches to 3200 W m−1K−1and outperforms PGS by 60%. The superior K of GFs is strongly related to its large and intact grains, which are over four times larger than the best PGS. The large smooth features about 11 µm and good layer alignment of GFs also benefit on reducing phonon scattering induced by wrinkles/defects. In addition, the presence of substantial turbostratic-stacking graphene is found up to 37% in thin GFs. The lacking of order in turbostratic-stacking graphene leads to very weak interlayer binding energy, which can significantly decrease the phonon interfacial scattering. The GFs also demonstrate excellent flexibility and high tensile strength, which is about three times higher than PGS. Therefore, GFs with optimized structures and properties show great potentials in thermal management of form-factor-driven electronics and other high-power-driven systems.
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| 2. |
- Li, Mengjun, et al.
(författare)
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Selecting and Testing of Cement-Bonded Magnetite and Chalcopyrite as Oxygen Carrier for Chemical-Looping Combustion
- 2022
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 15:14
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Tidskriftsartikel (refereegranskat)abstract
- Combining iron and copper ores can generate an oxygen carrier that has a synergic effect of high temperature resistance and high reactivity. In this work, typical cements available in the market were studied as binders to bind magnetite and chalcopyrite to develop a suitable oxygen carrier for chemical-looping combustion (CLC). A first selection step suggested that an aluminate cement, namely CA70, could favor the generation of oxygen carrier particles having good crushing strength, good particle yield, and high reactivity. The CA70-bonded oxygen carrier was then subjected to cyclic tests with CH4, CO, and H-2 in reduction and in air oxidation at temperatures of 850, 900, and 950 degrees C with gas concentrations of 5, 10, 15, and 20% in a batch-fluidized bed reactor. The increase in temperature promoted the fuel conversion. At 950 degrees C, the conversions of CH4 and CO reached up to 80.4% and 99.2%, respectively. During more than 30 cycles, the oxygen carrier kept a similar reactivity to the fresh carrier and maintained its composition and physical properties. The oxygen transport capacity was maintained at 21-23%, and the phases were CuO, Fe2O3, Al2O3, and minor CaS. In the used sample, some grains were observed, but the morphology was not greatly changed. Agglomeration was absent during all the cycles, except for the deep reduction with H-2.
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| 3. |
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| 4. |
- Zheng, Teng, et al.
(författare)
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Effect of H2S presence on chemical looping reforming (CLR) of biogas with a firebrick supported NiO oxygen carrier
- 2022
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 226
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Tidskriftsartikel (refereegranskat)abstract
- Biogas containing CH4 and CO2 can be used in CLR for H-2 generation, while the H2S presence may affect oxygen carrier activity and reforming property. In this study, a 2000 ppm H2S was mixed with modelled biogas (CH4/CO2 = 3/2) to explore its effects on the CLR process. Experiments were conducted in a batch fluidized bed using a firebrick supported NiO oxygen carrier. The presence of 2000 ppm H2S decreased the oxygen carrier activity, thus resulting in a significant lower gas yield from the biogas as compared to the cases without H2S. Increase of temperature slightly alleviated the interaction between H2S and the oxygen carrier, hence a slightly higher gas (H-2 and CO) yield was achieved at 950 degrees C than 750 and 850 degrees C. In reforming, H2S was mainly converted to CS2, while COS and SO2 were minors. After several cycles without H2S, the material restored its original activity. Sulfur element and NiS2 crystalline were found in the reduced oxygen carrier according to XRD, XPS, SEM-EDX, HRTEM-EDX and ICP-OES analyses.
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