теплоаккумулирующие материалы

Melts based on lithium salts are applied in various branches of engineering and scientific research [1]. It requires improved methods to search lor low-melting compounds and data on phase equilibrium in systems ot"three or more components. We have proposed a settlement- graphic way to select the salt compositions by two properties (temperature and specific enthalpy of melting) in the case studies the five-component system Li // F, Br, VO₃, MoO₄, SO₄.

In modem technological processes increase used molten multicomponent solt mixtures. Determination of the composition and melting temperature are important in application of the compositions, identification of patterns processes occurring during melting and solidification of alloys, as well as the phases in equilibrium at a given thermodynamic conditions, possibly in the study of phase diagrams. In this paper we propose a graphical method of calculation and choice of salt composition on the basis of the study five-component reciprocal system Li,K||F,Cl,VO₃,MoO₄ for use as electrolytes and heat storage materials.

An important feature when using low-melting mixtures of halides of s-elements as a refiner of electrolytes for chemical power sources and thermal storage materials in thermal batteries is the amount of volume increase in the melting process which can be calculated by the formula [1]:
ΔV = ((Vк – Vж) / Vк)·100% = (ΔV/Vк)·100%,(1)
where Vк – the volume of a solid substance (or mixture) at the melting temperature; Vж – the volume of liquid at the melting temperature (substance or mixture); ΔV – volume difference in the liquid and solid states of the substance.
Identification of ΔV is necessary because all the halides increase their volume, therefore melting increases the mixture of halides volume. So, when filling chemical power sources and storage heaters by mixtures it is necessary to keep a share of the free volume not only for expansion of the mixture in the solid (including the transition from one crystal structure to another) and liquid state, but also for increasing of the melting compounds volume. But, in the literature [2,3] provides data on the increase volume in the melting is not for everyone halides s-elements (table 1).