Experimental study of electrochemical mass transfer in an annular duct with the electrolyte nanofluid

Mass transfer processes during the forced transitional and turbulent flow of the nano-electrolyte through the horizontal annular channel were investigated. The fully developed hydrodynamic profile was considered. Mass transfer coefficients at the cathode attached to the inner surface of the channel were measured. The experiment was performed with the Reynolds numbers ranging from 2080 to 10430. Bulk ion concentrations in the electrolyte were measured experimentally during each test which minimized errors resulting from ion concentration decomposition. There occurred changes in the mass transfer coefficients depending both on nanoparticle concentration and the Reynolds number. With an increase in nanoparticle fraction, mass transfer was reduced. Measurements for the transitional and turbulent regime indicated that the mass transfer coefficients achieved their lowest values at the largest value of nanoparticle fraction. However, the reduction in mass transfer was not proportional to an increase in particle fraction. The maximum reduction of about 12% was observed for the largest Re numbers and the maximum particle fraction.