FUNDAMENTAL EQUATION OF STATE OF ARGON, SATISFYING THE SCALING HYPOTHESIS AND WORKING IN THE REGION OF HIGH TEMPERATURES AND PRESSURES

This paper discusses the problem of describing thermodynamic properties of a substance at high temperatures and pressures on the basis of the fundamental equation of state (FEoS). This FEoS has the following characteristics: it transforms into the virial equation of state in the region of low densities; it is converted into the Berestov equation in the vicinity of the critical point. FEoS testing has been carried out on known thermodynamic properties of argon and has allowed establishing its workspace: by the pressure up to 1000 MPa; by the temperature from the temperature of the triple point to 1200 K. It has been shown that our FEoS can qualitatively correctly describe the thermal surface of argon up to 17 000 K. A comparison of FEoS has been made with some well-known equations of state. When developing FEoS of argon, we have used elements of the similarity theory, which has allowed reducing the number of individual parameters of this FEoS.