Contribution to the modelling of industrial pleated filtersclogging by solid particles.
J.C Laborde, L. Del Fabro, V. Mocho, L. Ricciardi, workshop on particle loading and filtration kinetics in fibrous aerosols filters, 28-30/06/2002, University Karlruhe.
The communication presents some experimental and numerical results related to the clogging of industrial pleated filters, specially High Efficiency Particulate Air (HEPA) filters, by solid particles.
We propose to describe the clogging of pleated filters in three phases : first an in-depth filtration, as for flat filtering medium, which modifies rather the filter pressure drop; the second phase corresponds to a filtration on the surface of the filtering medium, along the pleats, and the last phase to a reduction of the filtering area which generates a significant increase in the pressure drop.
In a first part of the paper, are summarized some significant results of experiments which are committed according to the principle of the statistical design of experiments in order to study the influence of various factors; a factorial plan 24 is carried out. The factors considered are the filtration velocity vf (ranging between 1 and 10 cm/s), the height of pleats h (ranging between 27 and 48 mm), the distance between two pleats p (ranging between 2 and 3.5 mm), and the mass median aerodynamic diameter of the particles damm (ranging between 0.2 and 8 µm).
The second part concerns different contributions to the modelling of clogging. One results from a dimensionless approach based on the application of the theorem of Vashy-Buckingham and used previously to elaborate a semi-empirical model of initial pressure drop DP0 valid for different clean pleated filters; other derives from the Kozeny-Carman and Novick models in which a term of filtration area reduction is introduced.