Effect of advanced surfaces on the ammonia absorption process with NH 3/LiNO3 in a tubular bubble absorber

Identifier:  imarina:5127739

Handle: https://hdl.handle.net/20.500.11797/imarina5127739

Authors:  Amaris, C; Bourouis, M; Vallès, M

Abstract:
An experimental study was conducted to investigate the effect of advanced surfaces on the ammonia absorption process in tubular bubble absorbers using NH3/LiNO3 as a working pair at operating conditions of interest for absorption chillers. The tubular bubble absorber is a vertical double-pipe heat exchanger in which absorption takes place in the inner tube. In order to compare the effect of surface enhancement, a smooth tube and an internally micro-finned tube were tested. The inner tube of the absorber is made of aluminium and has an outer diameter of 8.0 mm and the micro-finned tube has internal helical micro-fins measuring 0.3 mm in length. The effect of tube length on absorption was also studied using two tube lengths (1 and 3 m) and two tube diameters (8 and 9.5 mm). Our results show that the absorption rate achieved with the micro-finned tube is up to 1.7 times higher than with the smooth tube at a solution mass flow rate of 40 kg h−1. We also found that absorption mass flux increases when tube diameter is reduced and decreases when tube length is increased.