Phase Diagram Predictive Model for a Ternary Mixture of Calcium, Sodium, and Potassium Nitrate

The development of low-melting mixtures is crucial for the diffusion of sustainable and green alternative energy sources, namely, CSP. Ternary mixtures containing sodium, potassium, and calcium are extremely promising as thermal fluids due to their good thermophysical properties, low toxicity and cost. Most literature studies on ternary mQ4ixtures refer to a particular commercial composition and there are few data regarding ternary phase diagrams. Thus, for improving the current understanding on this topic, further theoretical and experimental investigation on ternary mixtures is of utmost interest. An experimental campaign was conducted to study the binary subsystems of the ternary mixtures and develop a regular solution model for simulating the ternary phase diagram. To validate the model, several data were determined using an innovative experimental rheometric method. The results showed that a ternary contribution in the regular solution model is necessary and an empirical expression for this ternary parameter was proposed and validated.