Design, Modeling, and Thermal Validation of an Electric Resistance Furnace for High-Temperature Applications

Design, Modeling, & Thermal Validation of an Electric Resistance Furnace

Abstract

This paper describes the design, analytical modeling, and numerical thermal analysis of an electric resistance furnace intended to reach 1200°C. The geometry of a hexagonal heating chamber was used because it provides the highest level of effective heating volume and allows the use of commercially available lightweight refractory bricks. The one-dimensional steady-state analytical heat-transfer model and Finite Element Thermal Analysis (FEA) were performed with ANSYS APDL and ANSYS Workbench. The prediction by the analytical model showed an external wall temperature of about 404 K in the uninsulated furnace, which was too high, indicating excessive heat loss and that minute operating temperature conditions were not safe; the numerical results indicated the same temperature of 395 K with an error of 2.22%. This was counteracted by adding a 40 mm thick insulation layer in the form of ceramic fibers, which led to a reduction in the predicted analytical and numerical results of the external surface temperatures to 356 K and 326 K, respectively, and a standard deviation of 8.42. The insulated design exhibited a decreased amount of heat loss by about 45% and greatly enhanced the retention of heat in the heating chamber. The furnace was expected to reach a temperature of 1200°C in the furnace body in a period of one hour in operation, while keeping the exterior body of the furnace close to ambient temperature. The analytical and numerical results are very close and justify the proposed furnace design and prove the effectiveness of ceramic fiber insulation use in the high-temperature electric furnace.