A STUDY ON THE PRESSURE LOSS, HEAT-TRANSFER ENHANCEMENT AND FOULING CONTROL IN A VERTICAL PARTICULATE FLOW

In this study, the pressure loss, the heat transfer rate and the fouli ng characteristics of a particulate flow were investigated. Particles used were the glass beads of 3.0 mm diameter with 2.54 specific gravit y. The particles augmented the heat transfer at the flow velocities lo wer than 1.0 m/s. In this range, the heat transfer coefficient slighly increased as the particle volume fraction increased, and was almost i ndependent of the flow velocity. The particles also increased the pres sure loss at the flow velocities lower than 1.0 m/s. Above 1.0 m/s, ho wever, the heat transfer coefficient and the pressure loss were essent ially the same as those of flow with pure water. Through the flow visu alization study, the collision frequency on the wall by particles is s hown to be closely related with the heat transfer enhancement. The par ticles effectively controlled fouling. Fouling tests using ferric oxid e revealed that the particles effectively removed the pre-exsisting de posit as well as they prevented the deposit buildup.