Applying different heat flux intensities to simultaneously estimate the thermal properties of metallic materials

Abstract

This paper presents a different method for simultaneously estimating the thermal conductivity and the volumetric heat capacity of metallic samples. The contribution of this work consists in how it obtains the optimal conditions to produce such estimates. This method uses different intensities of heat flux in the same experiment, all in accordance with the analyses of the sensitivity coefficients. These analyses were performed along with an objective function to find both the best points to be analyzed and the best experimental configuration for estimating these properties. The method consists in positioning a uniform heat flux on the top surface and insulation on the bottom surface where a thermocouple is placed. The thermal properties were obtained by solving the heat diffusion equation for the one-dimensional model. The estimated values of the thermal properties for all materials present a difference lower than 2%, and an uncertainty analysis presented a result lower than 4% for all materials.

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

“…The experiment lasted 80 s each, following these conditions: 0–10 s with heat flux of 7709 Wm −2 ; 10–70 s with 1854 Wm −2 , and 70–80 s without heat flux. These conditions provide the best estimation of the thermal properties [17] and respect the hypotheses of constant thermal properties for each initial condition, since the difference between the initial and final temperature must be lower than 5 K. Lastly, the temperature was monitored in a time interval of 0.1 s so as to have more data.…”

“…To ensure the best region and the ideal condition to determine the thermal properties, two analyses were done: The first analysis corresponded to the sensitivity and objective function and the second concerned the best condition and design for the experiments [17].…”

“…The uncertainty propagation was considered to perform this analysis, as described in Carollo et al [17] and Taylor [24], and it is important to assure the reliability of the estimated results.…”

“…Additionally, the uncertainty analysis presented in this work considers the influence of the numerical and experimental temperature errors and contact resistance. This work presents the betterments carried out concerning Carollo et al [17].…”

Time Traveling Regularization for Inverse Heat Transfer Problems

“…The data acquisition system read temperature at a time interval of 0.2 s totalizing 1250 temperature points. The thermal diffusivity α = 3.77 × 10 −6 m 2 /s and thermal conductivity λ = 14.7 W/m.K of AISI 304 were obtained from Carollo et al [28]. The adopted values for heat flux and heating time were chosen in order to ensure a temperature difference lower than 7 • C. Therefore, the thermal properties may be considered constant in this temperature interval.…”