Free convective mass transfer at down-pointing truncated cones

Free convective mass transfer at down-pointing truncated cones was experimentally studied using the electrochemical limiting diffusion current technique. The total mass transfer coefficient has the same dependence on height as that of a conical surface; however, the values are higher because of the high mass transfer at the up-facing horizontal surface. The flow development after sudden switch on of the limiting current potential was observed. The flow begins as a ring of fluid rising from the upper cone periphery followed by necking of the plume and a steady-state situation arises in which there is a complex flow structure consisting of a multiplicity of close spaced interacting convection streams. The experimental total mass transfer data were correlated using a method which includes an interference factor taking account of the fact that the conical and up-facing horizontal surfaces of the truncated cones are exposed to fluid which has already been depleted in cupric ions as it flows up from the down-facing horizontal surface.