The thermal conductivity values (k) of adsorbents are one of the major factors that decide the pumping performance of cryo-adsorption vacuum pumps. There is limited data available in the literature that characterizes the ‘k’ values of adsorbents in cryogenic temperatures, due to the complexities in measurement methods. Most of the measurement techniques use the I D Fourier heat conduction equation, which involves measuring the temperature differences (?T) created with a known heat source, over a specific length of a test sample (?x), which is thermally isolated from its surroundings. Adsorbents in the powdered form cannot be held between the heat source and sink for the process, without using binders or by sintering it into test sections, which can alter its real ‘k’ value. A holder-based test method is described in the study which can test samples in their powdered form, in varying densities, and without using any additives. This method maps experimentally obtained the ‘?T’ value for heat conduction through the adsorbent loaded sample holder, against a calibration chart for thermal conductivity ‘k’, prepared from a simulated model of the setup. The COMSOL-based simulation model of the setup used to prepare the calibration chart, plots ‘?T’ values for all possible ‘k’ values in the predicted range for the material. This method can account for heat conduction in all directions, conduction of heat through the sample holder, and test the sample in its original form, even though it is powdered in varying densities.
Nazer et al. (Sun,) studied this question.