Augmentation of heat transport in laminar flow of polystyrene suspensions. I. Experiments and results

The effective thermal conductivity of suspensions of 50− and 100-μ-diam polystyrene spheres in aqueous sodium chloride or glycerine, flowing in laminar motion, has been shown to be a function of the state of the motion (unlike single-phase fluids) and has been seen to be as much as 3 times the thermal conductivity of stationary suspensions. Detailed experiments have indicated its dependence upon the particle concentration, particle size, shear rate, kinematic viscosity, and thermal diffusivity of the suspending liquid, and tube diameter and length. The Graetz solution corresponding to uniform wall temperature was used to determine the value of thermal conductivity in an apparatus calibrated with tap water. The over-all accuracy of the results is within 10%.