Thermal Conductivity of Aqueous Mg(NO3)2, Ca(NO3)2, and Ba(NO3)2 Solutions at High Temperatures and High Pressures

Abstract

Thermal conductivity of four aqueous Mg(NO3)2 solutions of molality (0.7507, 1.689, 2.895, and 4.5040) mol·kg-1, four aqueous Ca(NO3)2 solutions of molality (0.6771, 1.5235, 2.598, and 4.063) mol·kg-1, and Ba(NO3)2 (0.0781, 0.1594, 0.2442, and 0.3327) mol·kg-1 have been measured with a concentric-cylinder (steady-state) technique. Measurements were made at five isobars (0.1, 10. 20, 30, and 40) MPa for H2O + Mg(NO3)2, H2O + Ca(NO3)2, and H2O + Ba(NO3)2 solutions. The range of temperature was (293.15 to 591.06) K. The total uncertainty of thermal conductivity, pressure, temperature, and molality measurements was estimated to be less than 2 %, 0.05 %, 30 mK, and 0.02 %, respectively. The measured values of thermal conductivity were compared with data and correlations reported in the literature. The reliability and accuracy of the experimental method was confirmed with measurements on pure water, toluene, and H2O + NaCl with well-known thermal conductivity values. The experimental and calculated values of thermal conductivity for pure water from IAPWS formulation show excellent agreement within their experimental uncertainties (AAD within 0.44 %) in the temperature range from (308.4 to 704.2) K and at pressures up to 60 MPa. Correlation equations for thermal conductivity of the solutions studied were obtained as a function of temperature, pressure, and composition by a least-squares method from the experimental data. The AAD between measured and calculated values from this correlation equation for the thermal conductivity was (0 to 0.7) %.