FREE-CONVECTION MASS-TRANSFER BEHAVIOR OF A FIXED-BED OF RASCHIG RINGS

Natural convection mass transfer at a fixed bed of copper Raschig ring (aspect ratio = 1) has been studied experimentally using an electroch emical technique which involved measuring the limiting current of the cathodic deposition of copper from acidified copper sulfate solution. Variables studied were ring diameter, bed height, and physical propert ies of the solution. The data were correlated for the condition 1810 < Sc < 2532, 10.6 x 10(6) < ScGr < 21 x 10(7), and 0.17 < d/h < 1 by th e equation Sh = 0.15(ScGr)(0.32). A comparison between the present dat a and previous data at other packing geometry shows that the rate of n atural convection mass transfer at Raschig rings is less than that at spheres and cylinders. The importance of the results to electrochemica l reactor design is highlighted.