Power consumption of helical ribbon mixers in viscous newtonian and non-newtonian fluids

Using CFD and Ultrasonic velocimetry to Study the Mixing of Pseudoplastic Fluids with a Helical Ribbon Impeller

“…A K s value of 23 obtained by Curran et al [19] for a similar mixing system was used in the apparent Reynolds number calculations. This value is within the range of K s values (23-35.8) reported in literature [6,19,[40][41][42][43]. For Re a < 40, the slope is ≈-1 indicating that the flow is laminar for the range of impeller speeds considered.…”

“…A number of reasons have been postulated for the efficiency of these impellers. These include a large diameter that is just less than the vessel diameter [6] and spiral rotating elements [7], which on agitation produce a high secondary rotation in the tank giving rise to good liquid mixing in the entire mixing region regardless of fluid viscosity. This ensures the homogeneity of properties such as viscosity, temperature, and composition across the bulk fluid, leading to enhanced product quality [6].…”

Effect of rheological properties on power consumption with helical ribbon agitators

“…Also included in the same table are the calculated value of Kp using the semi-analytical methods due to Chavan and Ulbrecht (1973), Yap et al (1979) and the empirical correlation proposed by Shamlou and Edwards (1985). While the agreement between the predicted and experimental values of Kp is seen to be moderately good for the models proposed by Chavan and Ulbrecht (1973) and by Yap et al (1979), the correspondence with the results of Shamlou and Edwards (1985) is rather poor. Further examination of this table shows that the value of Kp increases with the decreasing agitator pitch and with the increasing blade width, albeit the latter is a rather small effect.…”

An analytical model for the prediction of power consumption for shear-thinning fluids with helical ribbon and helical screw ribbon impellers

“…However, for helical ribbon impellers with or without a screw, considerable confusion exists in the literature regarding the dependence of the constant K s on the fluid rheology (Chhabra, 2003). For instance, Hall and Godfrey (1970), Nagata et al (1971), Rieger and Novak (1973), Takahashi et al (1984) and Shamlou and Edwards (1985) have all concluded that K s is only a function of the mixer geometry and it is independent of the fluid rheology. On the other hand, the works of Yap et al (1979, 1992, 1997, 1998, Leuliet et al (1991Leuliet et al ( , 1992, Carreau et al (1993), Netusil and Rieger (1993), Cheng and Carreau (1994) and Cheng et al (1995) clearly suggest that the value of K s increases with the flow behaviour index of pseudoplastic fluids.…”