Semi-empirical predictive calculation of the thermal-physical properties of potassium-sodium melts based on their component data

Use of liquid-metal coolants in nuclear power plants has been the cause of unfailing interest in thermal-physical properties of metals and their alloys from both experimentalists and theorists. Power polynomials are used by experimentalists to approximate temperature changes in heat capacity, the coefficient of thermal linear (volume) expansion and other quantities. These polynomials have different form in different temperature intervals and need to be joined at the interval ends. This approach creates a number of difficulties in developing a unified methodology for calculating not only the thermal functions of metals, but also for predicting the behavior of their melts and alloys. The following was used in the paper to solve the problem at hand: the author's model of a two-phase local-equilibrium region (with different order parameters) and the modified rule of component mixing, taking into account the coordinated arrays of experimental data on the initial metals for calculating predictively the thermal-physical performance of potassium and sodium melts. It has been shown that using the model of a two-phase local-equilibrium region, new approximating functions and empirical formulas lead to a sufficiently adequate estimation of heat capacities, thermal linear expansion coefficients, densities, thermal conductivities and thermal diffusivities of melts. A discrepancy has been found between the mathematical description of the thermal conductivity of the K₅₆Na₄₄ melt and its experimental values.