An experimental study on solid‐liquid flow through rectangular ducts

Reduction in energy consumption has been the main concern of the workers in the field of solid‐liquid flow. Investigators have tried to achieve this objective in various ways. Two of the well‐known methods are: the addition of polymer solutions to the solid‐liquid mixture and the fitting of helical ribs inside regular circular pipes. In the latter case, the reduction is considerable, but it results in a very low rate of transportation. Chiu and Seman have reported considerable reduction of head loss in a square duct when compared to the flow through a circular pipe. In the present work, an experimental study has been underaken to compare the head loss for solid‐liquid flow in a circular pipe, with that for rectangular ducts of four different aspects ratios (width/height ratios), keeping the cross‐sectional area of each one of them to be the same. When the perforance of a circular pipe is compared with that of the other rectangular ducts, it seems that the square duct shows a better performance in the low operating range of velocity, whereas the rectangular duct of aspect ratio 1.5 presents a still better performance, from the energy requirement point of view, for practically the entire velocity‐range within which the experiment was conducted.