Experimental analysis on fluid flow and mass transfer characteristics of CMC solutions in wavy-walled tubes for steady and pulsating flow by PIV

Abstract This paper reports experimental results for fluid flow and mass transfer of sodium carboxymethyl cellulose (CMC) solution in wavy-walled tubes under both steady and pulsating flows where the PIV technique is employed. The rheological properties of the solution are revealed from the present experiment, and it is found that CMC solutions are featured with a shear- thinning behavior when the concentration is above 500 ppm regardless of temperature. The findings demonstrate that the increasing concentration makes the mass transfer performance degradation of CMC solutions. However, the mass transfer rate could be improved with the increasing amplitude of wavy-walled tubes in pulsating flow. The presence of reverse flow promotes the mass transfer and they are mostly distributed in the deceleration regime in one pulsating cycle. An optimal oscillatory fraction corresponding to the highest mass transfer enhancement is obtained. Furthermore, the phase shift phenomenon is observed in pulsating flow and the phase difference increases with the Strouhal number and amplitude of tube, but it is unaffected by the wavelength of the tube, the polymer concentration and the oscillatory fraction of the flow rate.