Adsorption characteristics evaluation of R134A and R404A on different adsorbents

Abstract

In order to design adsorption employed cooling or refrigeration system, it is inevitably required the knowledge of the adsorption isotherms and the isosteric adsorption heat for the assorted adsorbent/adsorbate pair. The physical adsorption phenomena occurs mainly within the pores and on the surface of the adsorbent. Since, the characteristics of each adsorbent-adsorbate pair is different than others. The knowledge of adsorption characteristics with the variation of temperature and pressure is necessary for the evaluation. However, these data are usually unavailable from the manufacturers of adsorbents. The objective of this study is to evaluate adsorption characteristics of R134A (HFC-134A) and R404A (HFC-404A) on different adsorbents experimentally by a constant volume variable pressure method at different adsorption temperatures ranging from 20 to 50 C and for pressures up to 5 bar. The forms of the isotherms obtained from the experimental measurements are similar in all cases and comparable to those reported in the literature for commercially available different adsorbents. Adsorption parameters are evaluated from the isotherms using the Dubinin-Astakhov (DA) equation. The concentration dependence of the isosteric enthalpies of adsorption is extracted from the obtained data. Further, the enthalpy of adsorption data are extracted, and correlations are provided for the different specimens investigated. These data are essential for the design of a thermally driven adsorption chiller employed the assorted pair.