EXPERIMENTAL INVESTIGATION ON A HORIZONTAL TUBES FALLING FILM ABSORBER WITH WATER-LITHIUM BROMIDE

摘要

The absorber is the most important component in absorption cooling systems and its performance has great influence on the overall efficiency. Falling film configuration is suitable for water-lithium bromide absorbers due to its associated low pressure drop and its great potential for removing large amount of absorption heat. Experimental study of the absorption process in a horizontal 19.05 mm tubes falling film absorber with water-lithium-bromide has been carried at operating conditions of interest for absorption chillers. The absorber is made up of twelve horizontal cooper smooth tubes forming one column. A sensitivity study of the solution mass flow rate on the absorber efficiency parameters is presented. The absorber efficiency parameters considered are: the absorption mass flux, the solution side heat transfer coefficient, the absorber thermal load, and the sub-cooling of the solution leaving the absorber. Moreover, the moving-window approach is employed for identifying steady-state regions from the recorded data. Results show that both mass absorption flux and absorber thermal load increase with solution mass flow rate. The increase of the solution mass flow rate significantly improves the tubes wetability, increasing heat and mass transfer rates. The degree of subcooling of the solution leaving the absorber ranges between 9 and 13 K, which means that the absorber is somewhat oversized.