Frequency response measurement of mass transfer in adsorbent particles and analysis of adsorption refrigeration

Modern design of adsorption systems requires both the modeling of adsorption cycles and the determination of the characteristics of adsorbents. This work considers both a simple apparatus for the gathering of both adsorption equilibrium and kinetic data and a model of an adsorption refrigeration cycle.; The first portion of this work involves the development of an apparatus for the measurement of adsorption equilibrium and kinetic data. A flow system has been constructed utilizing computer controlled mass flow controllers, pressure controllers and mass flow meters to allow both equilibrium and dynamic studies. The flow system and corresponding mathematical models are used to determine experimentally both equilibrium and kinetic parameters for various adsorbate/adsorbent systems. Both isothermal and non-isothermal models have been developed for both surface diffusion and linear driving force kinetics. These models have been applied to experimental data for carbon dioxide adsorbing on activated carbon and the adsorption of oxygen and nitrogen on a commercial carbon molecular sieve.; Both the equilibrium and kinetic data obtained agree well with published values. The adsorption of carbon dioxide on BPL activated carbon was found to follow a pore or surface diffusion type of behavior. It was also found that the resistance was independent of bulk particle diameter, indicating that the controlling resistance was within the micropores of the carbon. The adsorption of the gases on the carbon molecular sieve was found to follow a linear driving force model.; The second part of this work is the examination of a model of an adsorption refrigeration cycle, analyzing the effects of varying system parameters on the theoretical performance of the modeled system. The model simulates a “thermal wave” adsorption refrigeration cycle by utilizing equilibrium theory to determine the asymptotic “best case” performance of the cycle.; The predicted performance of the cycles is good. For the base cycle considered a coefficient of performance of 1.24 was obtained. Reducing the temperature of the heat source and raising the condenser temperature were found to reduce performance, as should be expected. Division of the adsorbent bed into sections to restrict flow was found to have little effect on performance for the conditions examined.; Two unexpected results were found. First, areas of the bed experienced loading increases during the desorption step and corresponding loading decreases during the adsorption step. Second, the sectioned beds did not reach operating pressure sequentially. Instead, the section of bed where the majority of the temperature wave was located became pressurized first.