Generalized power and Metzner constant Ks correlations for both combined helical-ribbon-anchor and helical-ribbon impellers in highly viscous Newtonian and non-Newtonian fluids and operating in the laminar regine are presented on the basis of regressive analysis of experimental data from this work as well as those from the literature. For combined helical-ribbon-anchor impellers the correlation is where for helical-ribbon impellers Moreover

it was confirmed from the results that power consumption for heli cal ribbon impellers is not directly proportional to the length of the impel-ler.