HEAT-TRANSFER AND FRICTIONAL PRESSURE-DROP CHARACTERISTICS OF MODEL NYLON FIBER SUSPENSIONS

Flowing wood pulp fibre suspensions exhibit drag reduction (frictional loss of the suspension less than that of the suspending fluid) at hig h flow rates. For flocculating suspensions, this region of drag reduct ion corresponds to a region of heat transfer reduction. These effects have now been studied for suspensions of nonflocculating nylon fibres in water Heat transfer and frictional pressure drop were measured for a wide range of bulk velocities (1 < u < 10 m/s), fibre concentrations (0 < C < 5 mass %), and length-to-diameter (aspect) ratios (20 < L/D < 120). The occurrence and magnitude of the measured drag reduction an d heat transfer reduction were strongly dependent on all three variabl es. The pressure drop results for the nylon fibres and the wood pulp f ibres were similar The trends in heat transfer ratio data were also qu ite similar however the reduction in heat transfer at high velocities was less for the nylon fibres.