Pressure drop and heat transfer for cocurrent upflow of dilute gas-coal particle suspensions in a circular tube

Pressure drop and heat transfer for dilute gas-coal particle suspensions fl owing cocurrently upward in a 0.498-in.-i.d. tube were measured and compare d to previously published results for cocurrent downflow. A 4ft-long electr ically heated test section followed a 26-ft-long pressure-drop test section . Room air was employed as the carrier gas for 300-mum (average screen size ) suspensions of coal particles. The gas Reynolds number was varied from 10 ,000 to 30 000 , with solids loading ratios up to 15 lb of solids/lb of gas . Frictional pressure drop for upflow was found to be greater than that for cocurrent downflow. The wall Nusselt number was slightly less than that fo r air alone but somewhat higher than that for cocurrent downflow. Particle Nusselt numbers were found to depend on the gas Reynolds number and the sol ids loading ratio and were almost identical with those for cocurrent downfl ow.