Dynamics study of ethanol adsorption on microporous activated carbon for adsorptive cooling applications

The present paper reports the experimental characterization of dynamic performance of three Ad-HEx configurations based on the activated carbon/ethanol working pair. The kinetic behavior of ethanol adsorption onto activated carbon was studied by the LTJ (Large Temperature Jump) method that reproduces the real conditions of isobaric stages of adsorptive cooling cycles. The study consists of two main parts: the first one is related to the adsorption kinetics of the Flat Adsorbent Bed configuration, composed of loose adsorbent grains placed on the metal support. While the second one describes the performance evaluation of finned flat - tube HEx configurations loaded with adsorbent grains. The effects of the grain size, the ratio S/m of heat transfer surface to the adsorbent mass and the Ad-HEx geometry are explored in detail in order to find the main factors affecting the adsorption dynamics. On the base of the main findings obtained, the practical recommendations on optimization of the Ad-HEx unit are formulated in order to enhance the specific cooling power of an adsorptive chiller. Furthermore, a comparison of the adsorption characteristic times between the activated carbon and a properly synthesized porous composite, composed of LiBr inside a silica gel host matrix is shown.