Several methods have been used to determine thermal conductivity and thermal diffusivity. Among these, the Hot Wire Method is widely used because it is a transient heat transfer method which allows the determination of these properties simultaneously and quickly. In this work, a reduced dimension metallic probe is used to obtain these properties for Polyvinyl Chloride (PVC) and Polyamide samples by using the Hot Wire Method. This method consists in passing a current through a resistance wire to generate heat, which increases the temperature of a probe inserted in a sample. From the heat dissipation it is possible to calculate the thermal conductivity. To determine the thermal diffusivity, optimization techniques are used to minimize an error function, defined by the square of the difference between the experimental and numerical temperatures. The numerical temperature is obtained by the solution of a one-dimensional diffusion equation in cylindrical coordinates, by using the Finite Difference Method with explicit formulation. The advantage of this study is the use of a small dimension probe allowing the use of samples with reduced dimensions. In addition it presents a new device to fasten the components into the probe. The estimated properties were in good agreement with the literature.
Thermal conductivity; thermal diffusivity; simultaneous estimation; heat conduction and optimization
