A Different Approach to Estimate Temperature-Dependent Thermal Properties of Metallic Materials

Abstract

Thermal conductivity, λ, and volumetric heat capacity, ρcp, variables that depend on temperature were simultaneously estimated in a diverse technique applied to AISI 1045 and AISI 304 samples. Two distinctive intensities of heat flux were imposed to provide a more accurate simultaneous estimation in the same experiment. A constant heat flux was imposed on the upper surface of the sample while the temperature was measured on the opposite insulated surface. The sensitivity coefficients were analyzed to provide the thermal property estimation. The Broydon-Fletcher-Goldfarb-Shanno (BFGS) optimization technique was applied to minimize an objective function. The squared difference objective function of the numerical and experimental temperatures was defined considering the error generated by the contact resistance. The temperature was numerically calculated by using the finite difference method. In addition, the reliability of the results was assured by an uncertainty analysis. Results showing a difference lower than 7% were obtained for λ and ρcp, and the uncertainty values were above 5%.

Finite Element Method and Cut Bar Method-Based Comparison Under 150°, 175° and 310 °C for an Aluminium Bar

“…A correlation can be inferred for the contribution of uncertainty. According to [32,33], the simulations by FEM performed, where the gradients are more significant, and strictly the heat leaks in the numerical model are not being considered, which could be taken as a reference to calculate heat losses and add a correction in the final uncertainty value [34]. On the other hand, the prediction of the temperature values that the CENAM cut-off bar equipment reaches when the heater operates maximum temperature makes it possible for an adequate selection of material for the fibreglass surface, because the area with higher temperature can reach up to 386 • C according to the error obtained in this work [35].…”

Special Issue: Thermal Analysis of Materials

“…Another set of papers deals with the development of new or application-specific approaches, namely laser interferometry techniques for high precision measurements on non-standard samples, such as composite truss structures [ 5 ]; measurements of high temperature compressive creep in spark plasma sintering apparatuses [ 6 ]; measurements of the density of liquid oxides with aero-acoustic levitators [ 7 ]; and the simultaneous estimation of thermal conductivity and heat capacity in metal alloys [ 8 ].The range of materials covered includes polymers [ 9 , 10 ]; natural complex inorganic materials, such as natural sorbents [ 1 ] and industrial-grade thermal insulation [ 4 ]; single phase ceramic materials, such as spinel MgAl 2 O 4 [ 11 ], rare earth sesquioxides [ 12 ], and double perovskite cobaltites [ 13 ]; metals, alloys, and intermetallic compounds [ 8 , 14 , 15 , 16 ].…”