DOI: 10.1615/ICHMT.2008.CHT
ISBN Print: 978-1-56700-253-9
ISSN: 2578-5486
COUPLED HEAT AND MASS TRANSFER DURING ABSORPTION OF WATER VAPOUR INTO LiBr-H2O SOLUTION FAN SHEETS
ABSTRACT
This work characterises both numerically and analytically the heat and mass transfer in a fan-shaped liquid sheet of LiBr-H2O solution that absorbs the surrounding water vapour inside an adiabatic absorber for absorption chillers. A model for the simultaneous heat and mass transfer into the fan-shaped liquid sheet is presented together with the assumptions and simplifications that yield to an affordable problem. The increasing of the mass flow rate in the sheet due to the absorption of vapour is included in the model, thus resulting in a nonlinear system of equations. The coupled temperature and water mass fraction flow fields in the sheet are numerically solved. Additionally an approximate analytical solution of the problem is obtained in form of a series solution.
Profiles of normalized temperature and mass fraction in main flow and transverse directions are presented. The radial distribution of local and mean Sherwood number is also evaluated. The results show the existence of temperature and mass fraction regions in the fan sheet, which are analogous to the regions present in non-expanding sheets. Good agreement between the fully nonlinear equations and the analytical approximation is found downstream of the boundary layer region. Result comparison for different sheet aperture angles is performed, confirming a significant reduction of the saturation length with the increase of the aperture angle.