HEAT TRANSFER ENHANCEMENT DUE TO TURBULENCE INDUCED BY PARTICLE MOTION IN GAS-SOLID FLUIDIZED BEDS

Heat transfer augmentation due to turbulence in the gaseous flow of a gas-solid fluidized bed is analyzed. Since the heat transfer in such beds is enhanced by various mechanisms, each mechanism's contribution can only be separately evaluated using special means. Therefore, we employed a new mass transfer measurement technique to measure the contribution of the turbulence induced by particle motion on the total heat transfer occurring around a horizontal test cylinder immersed in a fluidized bed. Results indicate that the mass transfer, i.e., analogous to convective heat transfer to or from the gaseous flow, is enhanced by the turbulence produced from particle motion on the front side of the cylinder surface, but that other heat transfer mechanisms besides turbulence contribute to the heat transfer augmentation taking place on the cylinder side walls and back-side surface.