4. Molten salts

4.1 Main heat transfer fluids. Physico-chemical properties

The most common molten salts are formed from sodium nitrite (NaNO ₂ ), sodium nitrate (NaNO ₃ ) and potassium nitrate (KNO ₃ ). Their main advantages are that they can operate at atmospheric pressure for temperatures between 150 and 550°C. Taken separately, these salts are only liquid above 300°C, but eutectics with significantly lower melting points can be produced.

The most common eutectics are in mass composition:

• a mixture of 40% sodium nitrite, 53% potassium nitrate and 7% sodium nitrate. This mixture, known as HTS1...