Abstract
Using the low density particles (Porithrene balloons) described in the 1st report, mean heat transfer coefficients from single row horizontal cylindrical tubes immersed in floating particles were measured from the standpoint of aiming to reduce the pressure drop of a fluidized bed heat exchanger. In this study, futhermore, in order to make particles stably float around tubes, rectangular tubes (aspect ratio : 30/3) were used because the change of the flow area between the tubes is small ; that is, the change of the flow velocity between the tubes is small compared with cylindrical tubes. The results show that (1)Lo/Lh≥1, and that mean heat transfer coefficients are independent of both Lo and Lh the same as the case for cylindrical tubes. (2) Mean heat transfer coefficients, decrease slightly more than those of cylindrical tubes. (3) But, as rectangular tubes are able to be arranged more densely than cylindrical tubes, the thermal performance under equal pumping powes is improved about three times for that of cylindrical tubes.
