The Thermal Conductivity of Water to 250°C and 350 MPa

An apparatus is described to measure the thermal conductivity of aqueous and polar fluids at high pressures. The pulse heated wire method is used with a modification to permit AC heating and measurement. Experiments were performed with water from 30°C to 250°C and from 0.1 MPa to 350 MPa. With a pressure increase from saturation pressure to 350 MPa, the thermal conductivity increases at 30°C from 0.610 to 0.757 and at 250°C from 0.617 to 0.849 Wm −1 K −1 . Isobars have maxima at 130°C for saturation pressure and at 200°C for 350 MPa. The accuracy of the present results is estimated to be ±0.8%. Isochors have no maxima. The thermal conductivity increases with temperature and density. A comparison with all previous high pressure data for water and with high pressure data for methanol, toluene and n‐heptane is made. The thermal conductivity of supercooled water at high pressures is discussed.