(654b) Enhanced Nanofluidization by Alternating Electric Fields

Experimental results are shown on a proposed technique to enhance the fluidization behavior of nanoparticle fluidized beds. This technique consists of the application of an alternating electric field to the nanofluidized bed. Nanoparticle agglomerates are naturally charged by contact and tribo-charming mechanisms and are therefore agitated by the action of the externally applied field. This agitation contributes to the increased drag on the agglomerates, and thus enhances gas-solid mixing. Three different electric field configurations have been tested: co-flow field, cross-flow field, and variable field configurations. According to our observations, the best results are obtained for the variable field configuration. In this arrangement, the electric field strength is higher at the bottom of the fluidized bed. The larger agglomerates, which usually sink to the bottom during fluidization due to stratification, become the most agitated. In addition, the weaker electric field at the top of the fluidized bed causes the smaller agglomerates near the free surface to be weakly excited. Consequently, fluidization is greatly enhanced while excessive elutriation is avoided. It is demonstrated that this technique is even suitable to achieve expanded fluidization states of unsieved nanopwder samples even though the fluidization state returns to be heterogeneous after the electric field is turned off.