Absorption of steam bubbles in lithium bromide solution

• An experimental bubble absorption column is constructed and operated.
• The absorption of steam bubbles in a hotter lithium bromide solution is tracked.
• A simple ordinary differential equation model is developed to describe the collapse.
• The model is demonstrated to explain 96% of the observed experimental variance.
• Parametric studies are conducted examining factors influencing the rate of absorption.

Absorption heat transformers are thermodynamic cycles that are capable of recycling waste heat energy by increasing its temperature. One of the most important unit operations in a heat transformer is the exothermic absorption of water vapour into a solution of choice at a higher temperature. Bubble columns are potentially an efficient means of achieving this. An experimental analysis is conducted which examines the absorption of single steam bubbles into a concentrated aqueous lithium bromide solution. The bubbles are tracked using a high speed camera, and their rate of absorption is modelled using a simple ordinary differential equation model. Accurate model predictions are obtained when oscillating bubble Nusselt and the Sherwood number correlations are utilised. The proposed model is capable of describing 96% of the observed experimental variability. Very large mass transfer coefficients of approximately 0.0012 m/s are obtained, which is higher than any previously reported values used in heat transformer absorber design.