Thermal Conductivity of Gases. II. Thermal Conductivity of Carbon Dioxide Near the Critical Point

The thermal conductivity of CO2 has been measured in a coaxial cylinder cell as a function of pressure over a range of temperatures from 3.66 to 75.26 °C. Particular attention was given to the measurements from 1 to 9 deg C above the critical temperature at pressures closely spaced to include the critical density. The thermal conductivity of CO2(g) near the critical point is very large compared to one atmosphere values around room temperature. At 1 deg C above the critical point the thermal conductivity reaches a maximum at the critical density. This maximum is greater than the maxima at higher temperatures. At 75.26 °C, 44 deg C above the critical temperature, little unusual increase at the critical density was observed. The rate of heat transport by convection in the critical region is also very large. This problem was studied carefully in order that the temperature differences used were restricted to the region of laminar flow, and that appropriate extrapolation procedures were used to find the rate of heat transfer by thermal conduction alone. Also, at densities and temperatures away from the critical region, new thermal conductivity values were obtained.