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In this study, a planar solid oxide fuel cells (SOFCs) apparatus with a 6 cm × 6 cm anode supported single cell based on a modified button cell was designed for operation in both regular cell and button cell configurations. The apparatus was assembled with a regular cell with an active area of 5 cm × 5 cm and with a button cell with an active area of 2.54 cm2. They consist of fuel and oxidant chambers that allow heat conversion and thus increase the temperatures of the fuel inlet and oxidant inlet streams. The chambers reduced the cooling effect, thereby improved the cell performance. In addition, a wire–in–tube–type heat exchanger was designed and fabricated. This device was installed in front of the fuel inlet of the SOFC apparatus to improve heat transfer to better increase the temperature of the fuel inlet stream. Results indicate that the fuel outlet temperature of the system with heat exchanger is much higher than that of the system without heat exchanger. Thus, the performance of system with heat exchanger is largely improved. This improvement means that the wire–in–tube type heat exchanger is proved to be effectively increases the hydrogen inlet temperature by enhancing heat transfer.

The development of suitable sealants for high-temperature solid oxide fuel cells (SOFC) is a major challenge, as such sealants must withstand harsh conditions. They must be inert at the high temperatures used in SOFC operation (i.e., resistant to environments composed of oxidative and reducing gases), as well as thermo-chemically and thermo-mechanically compatible with the materials with which they are in contact. This paper presents a post-experimental analysis of variously sealants—mica paper, flexible mica paper, and thermiculite 866—used in high-temperature SOFC operation. The sealants are exposed to air or hydrogen at 600 °C–1000 °C for 100 h. The goal of this work is to investigate the thermal expansion properties (thickness expansion, coefficients of thermal expansion CTE and porosity), mechanical stability, and leakage during midterm operation. After the sealants fired at 1000 °C, their relative thicknesses increased to around 0.98, 1.01, and 0.568 mm, respectively. The coefficients of thermal expansion CTEs (600–1000 °C) for mica paper and flexible mica paper were calculated to be from 8.0 × 10−4 K−1 to 10.0 × 10−4 K−1, the CTEs of thermiculite 866 were around 1.0 × 10−4 K−1. The relative porosity of thermiculite 866, as determined through the density method, changed from 15.4% to 28.7% for temperatures from 600 °C to 1000 °C, respectively. Scanning electron microscopy is used to investigate the structure of thermiculite 866. It is tested for leakage using hydrogen from 500 to 3000 cc min−1 at 25 °C and 800 °C. The leakage rates at 3000 cc min−1 are 4.06% and 8.4% at 25 °C and 800 °C, respectively, showing that thermiculite 866 is a suitable sealant for SOFC applications.

This study reports the manufacturing of its core device–hydrogen electrode supported cell of reversible solid oxide fuel cell (RSOFC) with use of different oxygen electrode (La 0.8 Sr 0.2 MnO 3−δ = LSM, La 0.8 Sr 0.2 MnO 3 /yttria stabilized zirconia = LSM/YSZ) and its operation under solid oxide fuel cell (SOFC) and solid oxide electrolyzer cell (SOEC) mode. In order to lower difficulties during cell assembly, acceptable curvature of hydrogen electrode supported cell is accomplished with improvement of manufacturing process. Also reported are the resulting performances, both in SOEC and SOFC modes, as a function of its operating parameters such as temperature. We found that the RSOFC performance improved with increasing temperature for all oxygen electrodes–LSM, LSM + YSZ. SOFC performance with oxygen electrode–LSM is a better option while SOFC/SOEC recycling with oxygen electrode-LSM/YSZ is more durable. Identical material composition and no obvious weak connection between oxygen electrode-LSM/YSZ and electrolyte after SOFC/SOEC cycling tests are the main reasons leading to minor performance drops compared to that with electrode – LSM.

Anode-supported cells are prepared by a sequence of hot pressing and co-sintering processes for solid oxide fuel cell (SOFC) applications. Commercially available porous anode tape (NiO/YSZ = 50 wt %/50 wt %), anode tape (NiO/YSZ = 30 wt %/70 wt %), and YSZ are used as the anode substrate, anode functional layer, and electrolyte layer, respectively. After hot pressing, the stacked layers are then sintered at different temperatures (1250 °C, 1350 °C, 1400 °C and 1450 °C) for 5 h in air. Different compressive loads are applied during the sintering process. An (La,Sr)MnO3 (LSM) paste is coated on the post-sintered anode-supported electrolyte surface as the cathode, and sintered at different temperatures (1100 °C, 1150 °C, 1200 °C and 1250 °C) for 2 h in air to generate anode-supported cells with dimensions of 60 × 60 mm2 (active reaction area of 50 × 50 mm2). SEM is used to investigate the anode structure of the anode-supported cells. In addition, confocal laser scanning microscopy is used to investigate the roughness of the cathode surfaces. At sintering temperatures of 1400 °C and 1450 °C, there is significant grain growth in the anode. Furthermore, the surface of the cathode is smoother at a firing temperature of 1200 °C. It is also found that the optimal compressive load of 1742 Pa led to a flatness of 168 µm/6 cm and a deformation of 0.72%. The open circuit voltage and power density of the anode-supported cell at 750 °C were 1.0 V and 178 mW·cm−2, respectively.

Heat and mass transfer characteristics of fin-and-tube heat exchangers with and without hydrophilic coating were reported in this study. The test exchangers consisted of three different louvre fin patterns and their corresponding plain fin counterpart. For completely dry test conditions, the enhancement level for the enhanced fin pattern decreases with increase of fin pitch. The Gray and Webb correlation considerably under-predicts the present 7.0 and 9.5 mm tube diameter plain fin samples. For dehumidifying test conditions, the effect of hydrophilic coating on the sensible heat transfer coefficients is negligible, and there are no detectable changes of the sensible heat transfer coefficients with change of inlet relative humidity. However, the pressure drops for the hydrophilic coated surfaces are sensitive to the inlet relative humidity.