Thermal Conductivity Of Carbon Dioxide Research Articles

Thermal conductivity of carbon dioxide in the temperature range 300–348 K and pressures up to 25 MPa

The thermal conductivity of carbon dioxide gas has been measured using a transient hot-wire apparatus at temperatures of 302, 316 and 348 K and at pressures up to 5.42, 24.38 and 24.56 MPa, respectively. The results at 316 K show a marked critical enhancement. The use of apparatus of this type near the critical point is discussed briefly and the results are compared with the expression for the critical enhancement in thermal conductivity given by Hanley, Sengers and Ely.

Thermal conductivity and effective diffusion coefficient for vibrational energy: carbon dioxide (350-2000K)

The thermal conductivity of carbon dioxide is measured from continuum heat transfer measurements in a carefully designed column in the temperature range 350 to 2000K and with an estimated maximum uncertainty of about 2%. The data are correlated with the following cubic polynomial in temperature, T: k(T)=-10.280+0.0942T-0.1937*10-4T2+0.2619 *10-8T3. Here k is in mW m-1K-1 and T in K. The conductivity values are compared with the other available data and with the predictions of various theories developed for polyatomic gas systems. The conductivity data are also employed in conjunction with theory to compute the effective diffusion coefficient for the transport of vibrational energy as a function of temperature.

Thermal Conductivity of Carbon Dioxide and Steam in the Supercritical Region

AbstractThe 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.

Thermal conductivity of carbon dioxide in the temperature range 100°C to 1075°C

The thermal conductivity, k, of carbon dioxide is measured by adopting the conductivity column method in the temperature range 100°c to 1075°c. The measurements are taken at various pressures between 12·5 and 50·5 cm of mercury where the k values are found to be independent of gas pressure. The estimated accuracy of k values is ±2 per cent and these are correlated within an average absolute deviation of 0·5 per cent by the following quadratic polynomial in temperature (T): Here k is in cal cm-1 s-1deg-1 and T in degrees Kelvin. The present measurements agree well with the existing data. However, the latter have a large scatter and consequently the present work helps in resolving some of the controversies faced by correlators of k data. The theoretically calculated k values are appreciably smaller than the experimental results and this disagreement is attributed to a different value for the diffusion coefficient characterizing the transport of internal energy in comparison to the more familiar one associated with the diffusion coefficient measured in a tracer experiment.

The thermal conductivity of carbon dioxide in the critical region: II. Measurements and conclusions

Experimental data for the thermal conductivity coefficient of CO 2 at elevated densities including the critical region are presented. It is shown that the thermal conductivity coefficient exhibits a pronounced maximum in the critical region. The behaviour of the thermal conductivity is compared with that of the specific heat and the viscosity.

The thermal conductivity of carbon dioxide in the critical region: III. Verification of the absence of convection

In the preceding paper an anomalous increase of the thermal conductivity of CO 2 in the critical region was reported. To ascertain that this increase is not a result of convection, in the present paper the origin and contribution of convection during experimental measurements of the thermal conductivity is studied with special attention to the parallel plate method used. The conditions are derived which this parallel plate method must satisfy. It is shown that in the actual experiments published in the previous paper convection is negligible and the increase of the heat transfer observed in the critical region results from an increase of the thermal conductivity only.

Thermal conductivity of gases. II. Thermal conductivity of carbon dioxide near critical point

[The thermal conductivity of C0 2 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 C0 2(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.