Measurement and Prediction of the Thermal and Electrical Conductivity of Al-Zr Overhead Line Conductors at Elevated Temperatures

In the present work, the thermal conductivity and electrical resistivity of the Al-0.25 Zr (wt.%) alloy have been investigated from 300 K to 600 K. The variations of thermal conductivity (K_total) with temperature were measured by using a radial heat flow furnace. The electrical resistivity (ρ) measurements of the alloy depending on the temperature were performed using the standard four-point probe method. The electrical conductivity (σ) was obtained by using the measured electrical resistivity. The thermal conductivity and the electrical resistivity coefficients were determined from the graphs of thermal and electrical resistivity versus temperature for the alloy. The electronic thermal conductivity (K_e) values were obtained from the Wiedemann-Franz and Smith-Palmer equations, and the values of K_L were obtained by subtracting K_e fromthe measured values (K_total). K_total is dominated by Ke, and K_e varies between 208-198 W/mK. The K_L decreases from 7.99 to 1.77 W/m K, and σ varies between 1.41x10⁷-2.80x10⁷ Ω^-1m^-1 in the range of temperature 373-600 K. The enthalpy of fusion (ΔH) and the specific heat capacity (C_p) during the transformation were determined. Thermal diffusivity (α) changes were calculated as a function of temperature from these obtained thermal data.

Keywords:
Electrical resistivity; Electrical conductivity; Total thermal conductivity; Lattice thermal conductivity; Electronic thermal conductivity; Al-Zr Alloy