GAS-CHROMATOGRAPHY STUDY OF THE ADSORPTION OF REFRIGERATING FLUIDS ONMICROPOROUS SOLID ADSORBENTS

Adsorption isotherms for microporous solids have been determined by el ution gas chromatography. Adsorbents are of 'molecular sieves' type; t heir utilization in affinity thermal machines is envisaged. These mach ines work in a relatively high domain of pressure for the adsorbate, s o the chromatographic technique is generally inadequate for their stud y. The possibility of increasing the maximal pressures reached by chro matography has been investigated in relation with: the carrier gas flo w rate, the length and width of columns, the injected adsorbate mass. This study has been made for different solid adsorbents (zeolite 4A an d 13X, silica gel), in different shapes (small stick, pellet, powder), and with different adsorbates (water, methanol, ethanol). In the most favorable conditions that have been derived, the qualities of the chr omatographic method, rapidity, simplicity and large range of measures, appear well fitted to the search of this kind of isotherms which does not require a great accuracy. (C) 1998 Published by Elsevier Science B.V.