Prediction of Pressure Drop in Non-Woven Filter Media Using a Hagen-Poiseuille Model

Abstract

An accurate estimation of the pressure drop across filter media is not an easy task considering the randomness of pore size and shape, and complexity in geometry of flow paths, particularly for non-woven depth filters. The pioneering work of Darcy laid the foundation of pressure flow characteristics through sand beds. This was followed by the work of Kozeny who proposed a theory to determine the pore size using porosity as a parameter. Carman modified the porosity-permeability relationship further to suit experimental results more closely. The pressure drop relationship using this expression is known as Kozeny-Carman equation. In the present work, the prediction results of Kozeny and Kozeny-Carman equations have been compared with those obtained from the Hagen-Poiseuille model which include the effect of tortuosity. The results indicate that the introduction of tortuosity effect alone can improve the prediction based on the Hagen-Poiseuille model over the Kozeny model, which underestimates the pressure drop across the filter media.