Flow in micro porous silicon carbide

Flow in porous Silicon Carbide (SiC) has been investigated in order to increase the understanding of the determining parameters. Porous SiC is used in the fabrication of ceramic membranes, for use in cross-flow and dead-end filtration. Therefore, a description of the flow would help to design more efficient filtration modules, and to improve the use of the existing modules. The investigation performed in this study consisted of preliminary calculations using the Navier-Stokes equation, and the linear Darcy’s law, together with experiments. The experiments were conducted on simple SiC-components such as plugs in tubes, and porous pipes. It was found, that the flow in porous SiC can be described with the linear Darcy’s law for pore sizes around 10 μm with porosity of 45%. However, Darcy’s law was found not to be applicable in the present case for porous pipes with a pore size of 10 μm and Re ≈ 10−4−10−2 based on mean particle diameter. The relationship between flow rate and applied pressure was found to be above proportional, which resembles the flow behavior of a pre-Darcy region. The reason for the pre-Darcy flow is argued to be trapped air bubbles in the porous SiC, which was argued to be very dependent on the structure of the solid matrix and on the particle size distribution. A hysteresis loop was discovered during the experiments with the porous pipe. This might verify the theory of lack of saturation, as this may be explained by the contact angle hysteresis between the air and the water due to rough surfaces of the SiC particles. Several suggestions of recommended further experiments are stated, as the experiments conducted has been concluded to be insufficient to give a fully qualitative description of the flow in porous SiC.