| The horizontal tube absorber is one of the most popular types of absorbers; however, fundamental two or multi-dimensional studies on this type of absorber are relatively limited. Two geometries of current interest are considered: a single horizontal tube and a coiled tube of zero pitch. It is shown that the flow and heat and mass transfer on the single horizontal tube is inherently unsteady locally because the gravity vector varies with position on the tube. A steady solution for the flow on a single coil is derived for the coiled tube geometry.;Analytical solutions for the fluid velocity, temperature and mass fraction are obtained for a wide range of parameters. Only, the rate of mass absorbed is required to be calculated numerically as the solution of a nonlinear integral equation. Results for the rate of mass absorption, temperature and mass fraction distribution over the liquid film, mass fraction on both sides of liquid-vapor interface, average temperature and mass fraction and heat and mass transfer coefficients are presented for various heat and mass transfer parameter ranges. Heat and mass transfer coefficients are also calculated analytically. The coolant side is also incorporated into the analysis, and the necessity to specify the temperature distribution on the tube wall may be eliminated in the resulted solution for the mass absorption rate.;The major results obtained in this work are as follows: (1) In the parameter ranges considered for the volatile vapor, vapor mass transfer need not be calculated directly. (2) Absorption is stronger at the top of the horizontal tube than that at the bottom since the film is thinner there. This means that low mass fraction fluid drops to the tube below.;The case of a single-component vapor is also considered for the case of a LiBr-water mixture have been compared qualitatively with a single data set obtained by Miller (1995). Despite the fact that the influence of multiple tubes and droplet formation is not accounted for, the results for the mass absorbed are in reasonable agreement with the experimental data. |
