Experimental and numerical study of adsorptive chiller dynamics: Loose grains configuration

Improvement of the dynamics of adsorptive chillers (ACs) is the main target for making them more competitive with absorption and compression machines. This paper addresses recent advances in understanding and optimizing the AC dynamics. This analysis is generally based on the dynamic experiments performed in a small "adsorbent-heat exchanger" (Ad-HEx) unit which closely imitates the conditions of isobaric stages of AC. All results concern configuration of Ad-HEx unit with n layers of loose adsorbent grains (n = 1, 2 and 4). The main experimental findings are discussed and practical recommendations on improving the AC dynamics are made. The Fickian diffusion model of coupled heat and mass transfer at isobaric stages of AC cycle is used to describe the experimental data and study the evolution of water concentration in vapour and adsorbed phases inside the grain as well as the effect of the adsorption isobar shape. These experimental and numerical studies have revealed that the AC dynamics can be significantly improved by a proper management of Ad-HEx design, durations of the isobaric phases of AC cycle, and the shape of adsorption isobar. (C) 2013 Elsevier Ltd. All rights reserved.