A theoretical study of discrete air phase migration contaminated with a volatile organic

Abstract

A theoretical study of discrete air phase migration contaminated with a volatile organic is developed in order to study air bubble migration through granular porous media in air sparging technology. The experiment is performed in a homogeneous, isotropic, and stationary porous medium presented by a fully saturated cylindrical column filled with 0.4-cm glass beads in an orthorhombic packing order. This study consists of two parts. The first part of the study describes the air bubble motion through saturated porous media, while the second part presents volatile contaminant transport in bubbly air flow. The first part of the study is developed in order to determine bubble rise velocity in four flow regimes i.e., steady state, quasi-steady state, unsteady state with the local term of the total acceleration only, and unsteady state, including the convective component of the total acceleration. The bubble rise velocity for each state is derived from the momentum balance equation for corresponding flow. Since in the quasi-steady state bubble rise velocity reaches the steady state over the short distance and in the unsteady state, with the local term of the total acceleration only it reaches the steady state over the short time, it may be considered that bubble's motion in a porous medium is in a steady state. The steady state solution shows that bubble rise velocity is dependent on the bubble size. In order to study the impacts of liquid and structural medium properties on bubble rise velocity, the Peeble and Garber's analyses of four types of bubble's motion in liquids are applied on the porous medium. Dimensional analyses show that motion of an air bubble rise in water is in the region IV, in which fluid flow is in a steady state. Moreover in this region, fluid flow can be assumed to be inviscid because of the large Reynolds numbers i.e., greater than 1400. The second part of the study is elaborated in Order to estimate the con contaminant ma s quantity accumulated in the air Phase 'mass transfer model between inimobile water and mobile gas Phase is al presented by advective-diffusion volatile contaminant transport equation in bubbly air flow Presented by Of this equation demonstrate that gas mass co,, contaminant. The results the bubble reaches the equilibrium concentrate concentration accumulated inside the number of bubbles on with liquid Phase instantly. injection. is larger in the continuous type than in the air