Influence of converging and diverging geometry on the pressure drop distribution in randomly packed beds

Abstract

Packed beds with diverging geometry find applications in packed bed reactors and converging geometry are used in the ethanol fermentation process. Experimental studies are conducted on pressure drop characteristics of converging and diverging packed beds with spheres of same diameter, spheres of different diameters, cylindrical inserts and mixing of spherical and cylindrical particles. The packing material spheres used is made up of stainless steel (SS304) having particle diameters 2.38 and 5 mm and cylinders of copper having 2 mm diameter and 4.6 mm height. The pressure drop is measured for a Reynolds number (based on particle diameter) range of 20–1200 with water as the working fluid. In this work, the effects of various converging and diverging angles of test section on the pressure drop in packed beds are studied. The pressure drop in packed beds with cylindrical inserts is higher as compared to pressure drop with packing of 2.38 and 5 mm spherical particles. The deviation in pressure drop for converging and diverging ducts at similar range of particle Reynolds number is less than 15% for majority of the cases. The pressure drop behavior for mixed packing of spheres and cylinders in converging and diverging channels are also explored in this work. The feasibility of using cylindrical packed bed correlation for very small differential elements of converging and diverging channels is examined in this study. The method used to calculate the pressure drop by using straight channel correlation is found to be applicable for both the converging and diverging channel packed beds.