Abudula Abuliti

Imaging of Single Phase Flow in Porous Media by High Resolution MRI

This paper presents the single flow in porous media to investigate CO2 flow velocity in porous media.We used high resolution MRI to visualize the fluid flow distribution and measure axial mean velocity in porous media.In the experiment, the porous media sample was packed with glass beads, with a porosity of around 0.4. Based the traditional spin echo sequence, we modified the sequence with flow encoding gradients in the flow direction .The sample was saturated. The water flow rates were 1ml/min、2ml/min、3ml/min and 5ml/min,respectively. First, the sequence was calibrated by pipe flow without porous media. As expected, the experimental images show parabolic velocity distribution. The velocity in the centre is high. Then the sample was measured with the same sequence. The images show that the velocity distribution is homogeneous in the porous media. In the boundary of the sample, the velocities are low because of wall-effect. Moreover, the mean velocities calculated from MRI images agree with the real velocities.These errors between calculated velocities and real velocities are small. It may be reduced by changing the experiment conditions.MRI is a useful technology for measuring flow in porous media.

Cotton-Fibers Used as Pore Former for the Anode with High Porosity and Long Cylindrical Pores of Solid Oxide Fuel Cells

The anode microstructure is crucial for the performance of solid oxide fuel cell(SOFC). The porous anode with high porosity and long cylindrical pores was prepared by using cotton-fiber as pore-former. With Ni-yttria stabilized zirconia (YSZ) as anode, La0.85Sr0.15MnO3-YSZ as cathode, YSZ electrolyte-supported cell was fabricated by slurry coating method. For a comparison, the unit cell with the conventional flour as anode pore former was prepared. All the as-prepared cells were measured in hydrogen at 650 to 800 °C. The microstructure of tested cells was observed by scanning electron microscopy (SEM). The SEM shows that the long cylindrical pores produced by cotton-fibers were beneficial to provide continuous gas pathways for rapid diffusion of fuel and reaction products in the anode. Compared the flour of 373.74 mW·cm-2at 800 °C, the maximum density of unit-cell prepared by cotton-fibers was higher than 900 mW·cm-2, which was attribute to an enlarger active reaction sites created by cotton-fibers for hydrogen oxidation.