Donor cell-finite element descriptions of wire-duct precipitator fields, charges, and efficiencies

Computations of electric field and charge density structures and resultant efficiencies in wire-duct electrostatic precipitators are described. The computational method is based upon the finite-element method as a means for computing the potential and electric field for a known charge distribution and a donor cell method that imposes conservation of charge in integral form as a means for computing charge densities for a known field structure, with iterative convergence to self-consistent solutions. The solution region is discretized by the Delaunay algorithm. This division simultaneously provides the triangles needed for the finite-element method and the Voronoi polygons over which charge conservation is imposed. Thus, a natural geometric interface is established between the finite-element method and the donor cell description. Results are shown in models that include the time-averaged effect of turbulence through a diffusivity coefficient, bipolar ionic species modeling back ionization, and the effects of particulate and ionic space charge