Experimental study on flow and thermal transport characteristics of moving packed bed through a channel featuring single column of inline cylindrical pins

Abstract

An experimental study is conducted to understand the fundamental flow and thermal transport characteristics of moving packed bed (MPB) through closely spaced parallel plates. An enhanced heat transfer concept based on cylindrical pins is experimentally investigated in this study. A simplified geometry involving two parallel plates as baseline configuration is considered, where the pin fin configuration involved a series of pin fins arranged in a single column, joining the two parallel plates. Steady-state heat transfer experiments have been conducted with particles of diameter ∼400μm and for three parallel plate spacings (3–7 mm) as well as three pin heights (3–7 mm). The heat transfer experiments involved parallel plates subjected to uniform heat flux with particles supplied at room temperature. The optical flow experiments were conducted to determine high spatio-temporal resolution near-wall flow-field of moving packed bed of particles. The experiments reveal that the separation between the parallel plates have a dominant effect on convective heat transfer, with lowest plate spacing yielding the highest heat transfer. Further, addition of pin fins results in local enhancement in flow velocities around the pin, while also resulting in a dead zone of stagnant or very slowly moving packed bed in the region upstream of the pins, and a void zone just downstream of the pin which does not feature particles. Pin fins also provide increased wetted surface area along with facilitating the conjugate heat transfer by transferring energy between the walls and the moving heat transfer media (HTM: particles). As a result of these complex mechanisms at play, the pin fin configurations had superior heat transfer performance compared to the baseline configurations.