Characterization of diethyl ether adsorption on activated carbon using a novel adsorption refrigerator

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2010-08, Vol.162 (1), p.234-241
• Main Authors: Al-Ghouti, Mohammad A., Yousef, Ibrahim, Ahmad, Rafat, Ghrair, Ayoup M., Al-Maaitah, Ayman A.
• Format: Article
• Language: English
• Subjects: Activated carbon; Adsorbents; Adsorption; Adsorption refrigeration; Applied sciences; Chemical engineering; Diethyl ether; Entropy; Exact sciences and technology; Heat and mass transfer. Packings, plates; Kinetic; Mathematical models; Refrigeration; Surface chemistry
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2010.05.035

In order to remove the limitations originating from inefficient heat and mass transfer in adsorption refrigeration/heat pump, an innovative arrangement design was proposed. It was equipped with meshed multi-tubular involving activated carbon in a sealed cylindrical adsorber. Related aspects of adsorption refrigeration key parameters were addressed. Working pair, activated carbon–diethyl ether, is used in the above system in order to determine the optimum adsorption refrigeration parameters. In order to estimate the adsorption characteristics and the adsorption capacity of the adsorbent, the adsorption isotherms of that adsorbent, with a specific adsorbate, are carried out. The measured adsorption data were adequately described by the Langmuir equation. The adsorption capacity of the diethyl ether on activated carbon at 26, 35, and 50 °C were 0.0159, 0.0220, and 0.0188 mmol/g, respectively. Two kinetic adsorption models namely pseudo-first and second order kinetic models were investigated. The thermodynamic parameters, Δ H°, entropy, Δ S°, and Gibbs free energy, Δ G°, of the adsorption process were also obtained from the gas adsorption experiments at various temperatures. These values were −45.84 kJ/mol, −88.87 J/(mol K), and −19.27 kJ/mol, respectively. The pseudo-first order model was not applicable in this adsorption system, suggesting that the adsorption process and the rate-limiting step was the pseudo-second order reaction. Therefore, the dominant mechanism might be a chemisorption process between the diethyl ether molecules and the activated carbon surface. The k 2, however, decreased as the initial diethyl ether pressure increased.