Design optimization of heater grid plates

Compact electrical heating and heat dissipating units are designed for several industrial applications where durability and stability of the unit under dynamic conditions have high priority. This paper initially investigates numerically the thermal characteristics of a custom build compact heater plate which can provide a geometrically optimized electrical resistance in application to heating or eliminating unwanted currents. The electrical resistance varies with the geometry and the locations of the cutouts (holes) in the plate. This analysis will significantly contribute to overall optimization of heating units that utilize these plates. The flow and thermal regimes between two adjacent ribbed plates with cutout holes were evaluated numerically by a finite difference code. This results in estimated local heat transfer coefficients which are used in the next phase of study. The second phase relates the heat transport to the temperature distribution on the plate by using a 3D finite element model. In the F.E. model, heat is generated due to non-uniform current through properly divided plate segments. Using this model the electrical resistance was evaluated as a function of hole geometry. Finally the geometry and location of ribs and holes were determined using a simple optimization technique in order to render the uniformity of surface temperature as desired for prevention of warping or excessive stresses.