Heat transfer and flow pattern in vertical liquid–solids flow

Abstract

Wall-to-bed heat transfer in hydraulic transport of spherical glass particles of diameter 1.20, 1.94 and 2.98 mm and in single-phase flow regime was studied. Experiments were performed by transporting the spherical glass particles with water in a 25.4 mm I.D. copper tube equipped with a steam jacket. In the runs without particles, the tube Reynolds number varied between 2280 and 21,300, while in hydraulic transport runs, the tube Reynolds number varied between 3300 and 20,150. The loading ratio ( G p/ G f) was between 0.07 and 0.328, and the fluid superficial velocity was between 0.29· U t and 2.86· U t, where U t represents the single particle terminal velocity. For these ratios, the voidage ranged from 0.715 to 0.895. The data for the heat transfer factor ( j H) in single-phase flow are correlated using a general form j H= f( Re). The data for wall-to-bed heat transfer in the hydraulic transport of particles show that an analogy between heat and momentum transfer exists. The data were correlated by treating the flowing fluid–particle suspension as a pseudofluid, by introducing a modified suspension–wall friction coefficient ( f w) and a modified Reynolds number ( Re m).