Thermal Conductivity of Carbon Dioxide and Steam in the Supercritical Region

The thermal conductivity of carbon dioxide and steam has been measured as a function of temperature and density using a concentric cylinder method. Earlier measurements of the thermal conductivity of CO2, obtained with a parallel plate method, covered a range of temperatures from 25 °C to 75 °C and revealed the existence of an anomalous thermal conductivity in the critical region. In this paper the experimental temperature range for the thermal conductivity of CO2 is extended to 700°C. The high temperature data enable us to determine a “background” thermal conductivity needed for a quantitative analysis of the anomalous thermal conductivity in the critical region. In addition, we provide experimental evidence that the thermal conductivity of steam exhibits an anomalous increase in the critical region similar to the behavior observed for the thermal conductivity of CO2.