Comparison of theory with experiment for single bubbles in charged fluidized particles

• Experimental bubbles in two beds with different levels of charging are compared.
• Single bubbles are smaller and more elongated in a bed with higher charge density.
• Instability of bubble roofs for particles of high-charge density was also observed.
• Numerical and experimental studies are in agreement in lower part of the column.
• Charge density distribution is important for comparison of theory and experiment.

Previous numerical studies, focused on single bubbles, predicted that electrostatics can cause bubble elongation in gas-fluidized beds. However, there was a lack of experimental evidence to test the numerical predictions. This study compares experimental bubble size and shape in beds with two levels of charging. The results indicate that single bubbles are smaller and more elongated in a bed with higher charge density. Instability of bubble roofs for particles of high electrostatic charge density was also observed.The experimental results are in agreement with the previous simulation results, with uniform particle charge density in the lower part of the bed and differences in the upper part. New simulations allowing for spatial variation of charge density show that bubble shape and stability are functions of the particle charge density distribution. Differences between simulation and experimental results are likely due to non-uniform distribution of charge on particles.

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