Thermal conductivity of aqueous solutions of $\mathrm{KCl}$–$\mathrm{NaCl}$–$\mathrm{CaCl}_2$ system at high temperatures and pressures

The experimental data are obtained on the thermal conductivity of mixed aqueous solutions of $\mathrm{KCl}$, $\mathrm{NaCl}$, and $\mathrm{CaCl}_2$ salts in a temperature range of $20$–$300^\circ$C, at a pressure of $5$–$50$ MPa, and a concentration of $3$–$20$ wt $\%$. The experiments are carried out on a setup realizing the relative method of coaxial cylinders. The error of the experimental data is $\pm(1.3–1.8)\%$. An empirical formula is presented which correlates the thermal conductivity of the solution with the densities of the solvent and solution, as well as with the thermal conductivity of water. This formula enables one to calculate the thermal conductivity of aqueous solutions of salts at high temperatures. The error of calculation by this formula corresponds to the experimental error. As an example, the values of the thermal conductivity of the $\mathrm{H}_2\mathrm{O}$–$\mathrm{KCl}$–$\mathrm{CaCl}_2$ system are calculated in a temperature range of $20$–$80^\circ$C. The maximal discrepancy between the experimental and theoretical data is $1.4\%$.