APPLYING DIFFERENT HEAT FLUX INTENSITIES TO ESTIMATE TEMPERATURE-DEPENDENT THERMAL PROPERTIES OF METALS
Luís Felipe dos Santos Carollo1; Ana Lúcia Fernandes de Lima E Silva1; Sandro Metrevelle Marcondes de Lima E Silva1
1 Universidade Federal de Itajubá - UNIFEI
doi:10.20906/CPS/COB-2015-0269
Resumo
This work presents a method for the simultaneous estimation of temperature-dependent thermal conductivity, λ, and volumetric heat capacity, ρcp, in samples of AISI 1045 steel. In this method, these properties are estimated simultaneously using the same experiment. Due to the initial temperature variation, the assembly is placed inside an oven. This model uses a constant heat flux on the upper surface of the sample and insulation condition on the bottom surface and the temperature is measured on the bottom surface by using type T thermocouple. Thus, the estimation of the properties is based on the analysis of the sensitivity coefficients. Based on this analysis, two different heat flux intensities are used. To estimate these properties, an objective function is minimized by applying the optimization technique BFGS. This function is defined by the square difference between the numerical and experimental temperatures plus the square of the systematic error caused by the thermal contact resistance. The numerical temperature is obtained by the solution of the proposed thermal model by using the Finite Difference method with an implicit formulation. Besides, uncertainty analyses are performed in order to ensure the quality of the obtained results. The estimated properties and the uncertainty are in good agreement with literature.
Palavras-chave: thermal properties; heat conduction; optimization; sensitivity coefficients; uncertainty analysis