Electric Nusselt Number in a Suspension of Spherical Hematite (α-Fe_2O_3) Particles

概要

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An experiment has been devised to evaluate the electric Nusselt number in a suspension of spherical hematite particles (hematite in distilled water). The experiment was conducted using a single platinum wire (diameter=0.025 rum) mounted along the axis of a copper cylinder (diameter=53 mm). The Nusselt number was evaluated for various experimental parameters such as time, electric field, frequency, orientation, charge and concentration of the colloidal particles. An increase in Nusselt number was observed in an ac field, and the increase was extremely sharp for pH values largely different from the isoelectric point (i.e.p.). A similar effect was also noted in a dc field at a very weak field strength. An increase in concentration of the colloidal particles increased the Nusselt number and a similar effect was also noted when the cylinder was moved from the horizontal to the vertical position. An attempt was made to evaluate the efficiency of convection using an empirical relationship and the results for ac and dc fields are presented.
社団法人応用物理学会の論文
1995-08-15