Effect of rhombus mesh on 3D falling film flow characteristics over microchannel flat tube for LiBr (Lithium bromide) absorber

Conventional circular tube and flat plate falling film flow absorbers are widely used in refrigeration sys-tems for high efficiency and small pressure drop. However, they suffer from poor wettability and large volume. This study proposed a novel falling film flow absorber, which is composed of the microchan-nel flat tube and rhombus mesh. The effect of rhombus mesh on falling film flow characteristics over microchannel flat tube absorber was studied numerically and experimentally. The results of the 3D VOF numerical simulations and experiments are in good agreement. The results show that the liquid film spreads horizontally after being blocked by the mesh edges and then converges toward the mesh cen-ter, resulting in increased coverage ratio. The liquid film thickness decreases as it goes over the rhombus mesh edges and increases as it converges the mesh inner region, leading that the fluctuation degree of liquid film thickness for the rhombus mesh microchannel flat tube is higher than that of smooth flat tube. Moreover, the liquid on the mesh edge flows perpendicular to the wall, leading to recirculation re-gion and stronger internal mixing. The results of this study would provide guidance for novel falling film heat exchangers in the field of refrigeration and chemical industry.(c) 2023 Elsevier Ltd. All rights reserved.