TURBULENT AUGMENTED HEAT TRANSFER FROM THE SURFACE OF AN IMMERSED TUBE IN A MAGNETOFLUIDIZED BED

Abstract

Heat transfer from horizontal heater heat-transfer probes submerged in a fluidized bed of iron particles exposed to a uniform magnetic field collinear with air flow is investigated experimentally at ambient conditions. Two heater heat-transfer probes have been designed, one for the measurement of total heat-transfer rates and the other for the measurement of local heat-transfer rates at different angular positions on the horizontal cylindrical heat-transfer surface. Measured total heat transfer rates have high values, and differences in the values for fixed and stabilized regimes from those in the fluidized regime are small. This is interpreted as implying that major heat transfer occurs by gas convection and it is shown that turbulence augments the gas convective heat transfer. This is also confirmed by direct measurements with a strip heater cylindrical heat-transfer probe at different angular positions. The mechanistic theory of heat transfer based on the concept of turbulent boundary layer on the heat transfer surface developed by the authors is found to successfully predict the measured heat-transfer rates from surfaces immersed in magnetofluidized beds.