OLIVEIRA, J. R. F.; http://lattes.cnpq.br/9962416898282222; OLIVEIRA, José Ricardo Ferreira.
Résumé:
Thermophysical characterization of materials used in engineering is very important for
realization of projects in the most diverse areas of knowledge where the phenomena
related to the process of heat transfer play an important role. Thermal diffusivity is a
very important thermal property on the analysis of problems of diffusion of thermal
energy. This work proposes the determination of this property using a periodic
temperature field. For this, an experimental device was built with principle of operation
in Angstrom’s method, which makes use of a periodic heat flow from a controlled
source, thereby generating a periodic temperature field in the test sample.
Thermocouples were installed on the samples for capture of signals generated by the
periodic heat flow. Amplitude and phase of these signals were obtained by means of
graphic analysis software. The thermocouple closest to the heat source was adopted
as reference, and the ratio and phase lag, between the thermal signals registered by
other thermocouples in relation to that registered by that thermocouple, were
calculated. These results were utilized in mathematical models to determine the
thermal diffusivity, whose identification can be performed either through the amplitude
ratio or through the phase lag between the temperature profiles. Samples utilized in
this work were stainless steel AISI 304, stainless steel AISI 316 and a shape memory
alloy of nickel-titanium. Identified values of thermal diffusivity of these materials, when
compared whit values available in literature obtained a good agreement, considering
the range of uncertainty presented.
