Hi y'all,
I was trying to meausre the pressure drop under a constant flow rate. For the porous media like titanium fiber felt and sintered titanium, when I use deionized water OR alcohol,the pressure drop kept increasing over time under a constant flow rate. This phenomenon only happened when I used liquid, for nitrogen, the pressre drop could keep constant.
I tried 3 houres of deionized water, the pressure drop increased from 1 kPa to 4 kPa and increasing, when I took it out and dried it, the initial pressre drop could go back to 1 kPa, also increasing, but with a smaller increase rate.
Does anyone know why? Looking for your answer.
Jiahua Li
1. In a liquid, the external pressure is equal to the sum of the kinetic and internal pressure of the liquid. If the external pressure (pressure differential) increases, the kinetic or internal pressure of the fluid therefore increases.
2. Porous materials are the same as semi-permeable membranes. During filtration, the interaction of water with the surface of titanium threads may increase with the formation of a gel layer of titanium hydroxide. It blocks the pores and an increase in pressure is necessary to overcome the obstacle.
The two reasons presented are interrelated. Experiments are needed to elucidate the detailed process.
Pressure drop may be increased due to pores occupied with fine particles. You can measure present bed height and compare with initial bed height. The height must be decreases.
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