Residence time distribution of particles during two-phase non-Newtonian flow in conventional as compared with helical holding tubes

The residence times of multiple particles during the flow of a non-Newtonian suspension through a conventional holding tube assembly were compared with that in a helical holding tube assembly of identical length and tube diameter. The residence times were measured for different combinations of process parameters (viscosity, flow rate of fluid, size and concentration of particles). The effects of these parameters on Residence Time Distribution (RTD) of particles was determined and dimensionless equations were developed to predict the mean, minimum and standard deviation of residence times. The RTDs in the helical holding tube were found to be narrower than in the conventional holding tube. The RTD of particles at all combinations of process parameters were normally distributed. The ratio of mean to minimum residence time was within 1.05 to 1.11 in the helical holding tube and 1.06 to 1.16 in the conventional holding tube for the range of parameters studied.