Thermophysical properties and application of LiNO3–H2O working fluid

• The systematic thermophysical data of LiNO3–H2O binary system were measured.
• Research shows that the corrosivity of LiNO3 solution is lower than LiBr solution.
• The performance of the absorption heat pump cycle is analyzed and compared.
• The cycle with LiNO3–H2O achieves higher COP than that with LiBr–H2O.
• The cycle with LiNO3–H2O needs lower temperature for driving heat source.

Vapor pressure (293.15 K-423.15 K, 50%–70%), specific heat capacity (303.15 K-373.15 K, 45%–60%) and specific enthalpy (303.15 K −373.15 K, 45%–60%) of LiNO3–H2O working fluid were measured. Dissolution heat of LiNO3 at 294.15 K was also determined. The corrosion behaviors of carbon steel, stainless steel 304 in LiBr and LiNO3 solutions were investigated at the temperature of 453.15 K, and the corrosivity of LiNO3 solution was obviously less severe than that of LiBr solution. Based on the measured data, performances of an absorption heat pump cycle based on LiNO3–H2O has been investigated and compared with the LiBr–H2O heat pump cycle under the same conditions. The results show that the cycle based on LiNO3–H2O has an advantage of 6.3 °C in the temperature grade of driving heat source against that based on LiBr–H2O, while the COP based on LiNO3–H2O is slightly higher than that based on LiBr–H2O.

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