Electrokinetic energy conversion of power-law fluids in a slit nanochannel beyond Debye-Huckel linearization

Electrokinetic energy conversion of power-law fluids is analyzed in a slit nanochannel. Electrical potential distribution is considered without Debye-Huckel linear approximation. The general analytical expressions of flow velocity and streaming potential are obtained for arbitrary power-law behavior indexes. Due to the strongly nonlinear constitutive relation of power-law fluids, the energy conversion efficiency is analyzed numerically. Results show that the electrokinetic energy conversion efficiency can be underestimated for the same physics parameters, when the Debye-Huckel linear approximation is applied. The conversion efficiency of pseudoplastic fluids is larger than that of dilatant and Newtonian fluids. The maximum in conversion efficiency of pseudoplastic fluids (n = 0.8) is about 5% and it is more than 78% than that of dilatant fluids (n = 1.2). Finally, the optimal flow parameters exist and such optimal values can be used to design an energy converter with high conversion efficiency. (c) 2022 Elsevier Ltd. All rights reserved.