Regenerative furnaces, which are widely used in industry, are among the most modern furnaces. These furnaces use burners with a thermal efficiency higher than the conventional ones. Aluminum, glass, ceramic and steel industries can use this technology and greatly reduce their fuel consumption. In this project, the functioning of these burners is studied. Regenerative burners are also called High Temperature Furnaces. Modeling of half-working-cycle of such furnaces by four active burners is studied in this project. Many different methods are selected to reach a successful model. Though all the results are in good agreement with experimental data, however complete numerical convergence is not achieved. At the end, the final results are presented as furnace and slab temperature curves. Moreover, temperature, velocity, and species concentration contours are other part of the results. Controlling the furnace pressure in desirable range is also considered. This pressure control will retain furnace pressure at atmospheric limit leading to lower heat losses from the hot gases exhausted from the furnace. A moment closure method with an assumed ? probability function for mixture fraction is used in the present work to model the turbulent non-premixed combustion process in the furnace. Two radiation models are used to calculate the radiation transfer source terms in the energy equation. The P1 and DO radiation models are compared in this project. There were no difference between the two selected models in the final results, but DO method reaches convergence faster than P1. The suitable negative pressure at the outlets of the furnace was calculated to be 1300 Pa with no regard to head losses caused by regenerators. The reason of non-convergence in this project to solve combustion equations with Fluent software. All of the effects such as geometry, quantity and quality of computational grids and numerical solution progress, with defining variety of under-relaxation coefficients for all the equations, were completely studied. Keywords Regenerative Furnace, Regenerator, Heat Recovery, Industrial Combustion Modeling, Mixture Fraction, Reheat Furnace.