Effect of noncondensable gases on the adsorption properties of adsorbent porous media

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Bayman O. A., ÇAĞLAR A.

JOURNAL OF THE FACULTY OF ENGINEERING AND ARCHITECTURE OF GAZI UNIVERSITY, cilt.40, sa.4, 2025 (SCI-Expanded, Scopus, TRDizin)

Özet

Noncondensable gases, such as air, can infiltrate adsorption systems operating at negative gauge pressures, significantly affecting their performance. This study investigates the impact of air on the adsorption and desorption behaviors of silica gel-water and Zeolite 13X-water pairs. Controlled amounts of air were introduced into an experimental setup comprising an adsorbent bed and an evaporator/condenser, with experiments conducted at varying temperatures. Adsorption and desorption processes were initiated by modulating the adsorbent temperature while maintaining constant evaporator/condenser conditions. The effects of air were assessed based on changes in adsorption and desorption capacities, pressure variations, gas and adsorbent temperatures, and adsorption/desorption hysteresis. Results reveal significant reductions in adsorption and desorption capacities with increasing air content, with desorption processes being more affected. Adsorption capacity decay exhibited an exponential trend for silica gel and a parabolic trend for Zeolite 13X. Higher evaporator/condenser temperatures mitigated performance losses, while systems with smaller desorption-adsorption temperature differences were more adversely affected. The findings emphasize the critical importance of preventing air leakage in adsorption systems. Even trace amounts of air, constituting only about 0.3-0.9% of atmospheric pressure, can significantly reduce system efficiency.