In this work, a consolidated experimental apparatus for measuring the density of liquids, such as high pressure and metastable states, based on the isochoric method, was exploited to measure thermal properties of seawater. Density of standard seawater was measured in a wide range of temperature and pressure, specifically from (261.15 to 313.15) K and up to 110 MPa. All terms contributing to the uncertainty in determining the volume and the mass of the specimen were evaluated, obtaining a relative expanded uncertainty of seawater density around 0.03% ($k=2$). Experimental results were fitted by using a 8-parameters function of specific volume as a function of temperature and pressure. Using the obtained expression, density, isobaric thermal expansion, and isothermal compressibility of seawater were calculated from (263.15 to 313.15) K and for pressures between (1 and 105) MPa. A comparison with the predictions obtained by the Thermodynamic Equation of Seawater - 2010 (TEOS-10) shows a general good agreement that worsens when metastable states are considered.

在这项工作中，基于等容法测量液体密度（如高压和亚稳态）的综合实验装置被用于测量海水的热特性。标准海水的密度在很宽的温度和压力范围内测量，特别是从 (261.15 到 313.15) K 和高达 110 MPa。对确定样品的体积和质量的不确定度有贡献的所有项都进行了评估，获得了大约 0.03% 的海水密度的相对扩展不确定度（$克=2$）。通过使用作为温度和压力函数的比体积的 8 参数函数拟合实验结果。使用获得的表达式，海水的密度、等压热膨胀和等温压缩率由 (263.15 到 313.15) K 和压力在 (1 到 105) MPa 之间计算。与通过海水热力学方程 - 2010 (TEOS-10) 获得的预测进行比较，表明普遍良好的一致性在考虑亚稳态时会恶化。