Document Type : Regular Article


University of Tehran



The effect of adding isopropanol (ISP) to nitrogen as the fluidizing gas on the hydrodynamics of fluidization of hydrophilic titanium nanoparticles was studied. It was shown by the pressure drop method that adding ISP reduces the minimum fluidization velocity. Wavelet transform of pressure fluctuations of the bed was employed to identify the hydrodynamic structures. Energy of hydrodynamic structures was evaluated in each fluidization mode. It was shown that ISP reduces the inter-particle attraction forces by replacing the hydroxyl group of the hydrophilic nanoparticles with an alkyl group. Energy and recurrence analysis were used to define the characteristics of fluidization when adding ISP to nitrogen gas. The energy of macro structures increased when using ISP, indicated a decrease in the number of bubbles and an increase in the bubble size due to the reduction of attraction inter-particle forces. The increase of white local areas in the recurrence plots also showed the increase of bubble size. Recurrence quantification analysis showed the increase of the larger-scale phenomena (i.e. bubbles) in the bed.


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