Abstract
In order to improve the performance (specially pressure drop) of a fluidized bed heat exchanger, low density particles (polystyrene balloon ; mean densities ρ p of 322 and 742 kg/m3, mean diameters of 1.0 and 1.5 mm) were employed. The tests were conducted with cylindrical tubes of 10 mm diameter by varying the location of the tubes Lh, static bed height Lo, tube pitches P and air velocities from 0.08 to 2.0 m/s. Mean heat transfer coefficients were evaluated in relation to pressure drop. The results show that (1) Lo/Lh≥1, and mean heat transfer coefficients are independent of both Lo and Lh. (2) As the change of the local velocity in the flow region between the tubes become large as the tube pitch decreases, the mean heat transfer coefficient decreases, because the particules can not float stably around the tubes. (3) On the contrary, the pressure drop of the tubes hardly increases. Therefore, as a dense arrangement of tubes can be designed, the thermal performance is considerably improved.
