| OCR Text |
Show Computer simulations of glass furnaces are becoming a very good economic tool for evaluating the design and control strategies to improve energy efficiency, process stability, and emissions control. Current state-of-the-art technology is capable of mathematically formulating the physical phenomena important to the glass manufacturing process, such as, melting, convective flow, combustion, soot generation, radiation, and N O x emissions. 2.0 MATHEMATICAL MODELING An accurate and useful model of combustion zone behavior inside the furnace must include the effects of radiation, conduction, convection, mass flows, enthalpy changes, flame energy release rate and soot generanon. To this end, the governing transport equations for the mean fluid motion, species, and enthalpy are solved in the combustion space using the commercial computational fluid dynamics package F L U E N T 5.0. The mean fluid motion represented as the time averaged equations for the conservation of momentum is written as: d ( PUjUi + pSg-U du, f dUj 2 dUk dx> dxi 3 dXk d - P gt+-(pujur) = 0 OXi (D where u, is the velocity component in the direction of coordinate Xj, p is the fluid density, g, is the magnitude of the gravitational acceleration in the i-direcrion, p is the pressure, ji is the laminar viscosity, and the operator 5jj is unity for i=j and zero when i*j. The last term (Reynolds stresses) is modeled using the "two-equation" k-e model: -(PUJUT)= M, dut +duj 2duk dxj dxi Sdxk (2) where \it is the turbulent viscosity that m ay be related to k and e by: iu, = c,k2/s (3) where c^ is a constant of the model. For closure, the following differential equations for k and e are also needed to be solved: |
