The Effect Of Pulsed Flow On The Heat Transfer Coefficient Of A Vertical Tube Suspended In A Fast Fluidized Bed
Date of Award
Master of Science (MS)
An experimental study was conducted to determine the effects of pulsing the fluidizing air on the heat transfer of a small vertical cylindrical heater suspended along the axis of a 101.9 mm diameter fast bed. Spherical aluminum metal power with a density of 2700 kg/m3 and dp50 of 107 μm was used in this investigation. Experiments were first conducted without pulsing the air supply. Solids fractions were observed as high as .0154 with superficial velocities from 1.98 m/s to 4.04 m/s and recirculation rates up to 27.6 kg/m2 s. The maximum heat transfer observed was 74.1 W/m2 K at a solids fraction of .0152 and solids recirculation rate of 25.3 kg/m2 s and at a superficial velocity of 2.80 m/s. Heat transfer was found to increase with increasing solids fractions and solids recirculation rates and decreasing velocity. A diaphragm valve was used to pulse the air supplied at regular periodic frequencies up to 12 Hz. Pulsed operation increased the observed heat transfer for frequencies between 1 and 2 Hz. A maximum increase of 32.7% in heat transfer was observed at 1.5 Hz. High pressure drops across the distributor plate were found to negate the effect of pulsation on heat transfer. A correlation was prosed to estimate heat transfer for non-pulsed tests based on suspension density. A correction factor was developed to predict pulsed flow results for cases with low pressure drop across the distributor plate.
Curran, Tyler, "The Effect Of Pulsed Flow On The Heat Transfer Coefficient Of A Vertical Tube Suspended In A Fast Fluidized Bed" (2016). Theses and Dissertations. 1885.