Effect of structure and operation parameters on heat and mass transfer coefficients of single-bubble absorption for lithium bromide solution

Bubble absorption has an efficient performance in absorption units, and lithium bromide (LiBr)-H2O is the most popular working medium in absorption system due to its safety and environmental protection. Limited to the vacuum operation, the researches of bubble absorption for LiBr solution are less reported and the bubble absorption characteristic for LiBr solution is still not clear. In this study, a single-bubble heat and mass transfer model is established to investigate the heat and mass transfer coefficients of bub-ble absorption for LiBr solution under vacuum condition. A visible experimental platform is established to validate the feasibility of vacuum operation and the model accuracy. The experimental results showed the relative deviation is less than 11.9%. Base on the current model, the effects of structure and operation parameters are comprehensively analyzed to explore the appropriate configuration. The results indicate that the heat and mass transfer coefficients increase significantly with the increase of the orifice diam-eter and the bubble velocity, while they reduce with the increase of solution concentration. It can be explained that large orifice diameter expands the contact area, and high velocity strengthens the convec-tion, which promote the absorption. Dilute solution concentration reduces the viscous force and surface tension, thereby enhancing the heat transfer. It is expected to provide guidance for the heat and mass transfer mechanisms and contribute to advance the structure and configuration of absorption system.(c) 2022 Elsevier Ltd. All rights reserved.