MIXED CONVECTION MASS-TRANSFER STUDIES OF OPPOSING AND AIDING FLOW INA PARALLEL-PLATE ELECTROCHEMICAL FLOW CELL

Studies of combined natural and forced convection in a vertical parall el plate electrochemical cell in laminar conditions in cases of opposi ng and aiding flow are reported. In an ongoing project it was necessar y to identify conditions in which natural convection had no significan t influence on mass transfer rates at the cell walls so that data coul d be validly compared with purely laminar flow computational models. F or the different electrode lengths investigated, natural convection do minated at low Reynolds number and there was no Reynolds number depend ence. At high Reynolds number the data approached the laminar flow sol ution. At intermediate Reynolds number, however, there existed a disti nct region where free and forced convection were significant. At high electrolyte concentrations data did not merge with laminar flow equati ons until Re = 1000 and low electrolyte concentration data for the lar ge plate could not be compared with numerical predictions below Re of 250. An attempt was made to compare the data with those of other worke rs on combined forced and natural convection heat and mass transfer.