Heat transfer in industrial furnaces. Annual report (Apr 90 - Mar 91)

A complete mathematical model of the combustion space of a direct fired furnace has been developed. The model is capable of predicting velocity distributions, flame shape, radiant heat fluxes, and convective heat transfer under steady operating conditions. The model is based on the solution of the governing differential equations for mass conservation, momentum, energy, chemical species, turbulence, and radiation. The furnace space model has been exercised parametrically and a sampling of the generated results is presented in this report along with a detailed description of the model itself. With regard to indirectly fired furnaces, the development of a batch furnace model has been completed and parametric studies of furnace performance have been conducted by exercising this model. Significant accomplishment in modeling indirectly fired furnaces has been the coupling of a previously developed radiant tube model with the furnace space model. This combined model represents a complete and consistent description of an entire indirectly fired batch reheating furnace. For a given furnace geometry, it is now possible to specify the firing rates in individual tubes and predict the resulting temperature-time history of a batch load while also predicting the exhaust temperature from each tube.