Estudo teórico de um forno intermitente a gás natural, para a indústria cerâmica: modelagem e análise térmica transiente.

Abstract

Drying and firing of ceramic products are processes that require high energy consumption. Making these processes more efficient can improve product quality, reduce energy consumption and processing time and, consequently, promote economic and environmental gains. In this sense, this work aims to theoretically quantify the heat transfer that occur in an intermittent ceramic kiln operating with natural gas during the heating and cooling stages, with and without thermal insulation. All proposed mathematical formulation is based on the principles of energy conservation (first law of thermodynamics and Fourier law). All the study is done via mathematical procedures implemented in Excel software and experimental design. Results of heat losses, temperature distribution in the thermal insulation and energy gain are presented and analyzed. It was verified that the greatest heat loss occurs by radiation in the sidewalls of the equipment, and that a considerable amount of energy is required to heat the sidewalls, base and ceiling of the kiln. The fiberglass, acting as thermal insulation, is the material that provides a greater reduction in the maximum external surface temperature and a greater energetic gain, when compared to the kiln without thermal insulation. From the factorial experimental design method, it was possible to obtain predictive mathematical models that quantify the influence of the thickness and other thermophysical properties of the insulation material on the energy gain and the maximum external surface temperature of the kiln.