Modeling water vapor adsorption/desorption cycles
Hefti, Max ; Mazzotti, Marco
In: Adsorption, 2014, vol. 20, no. 2-3, p. 359-371
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- This modeling work deals with the adsorption of water vapor on different porous materials where it undergoes capillary condensation and its adsorption/desorption isotherms exhibit hysteresis. The focus is on the description of the so called scanning curves, i.e. the adsorption/desorption isotherms observed when such an adsorbent is repeatedly loaded and unloaded in a range of conditions where hysteresis is observed, and on the simulation of fixed bed adsorption/desorption cycles. We use an approach originally developed by Štěpánek et al. (Chem Eng Sci 55(2):431-440, 2000), and expand it so as to include more general isotherms (not only the Dubinin-Radushkevich and Dubinin-Astakhov model, but also the Guggenheim-Anderson-de Boer model and the Do and Do model) and to allow for less than infinitely fast heat transfer, so as to consider non-isothermal situations. From a modeling point of view the results are satisfactory and highlight the need for better experimental data on water vapor adsorption, which need to be measured in enhanced experimental set-ups, capable to tightly control the relative humidity of the gas phase.