Gas absorption in a hydraulic air compressor. Part I: Simultaneous hydrodynamic and mass transfer bubbly flow model

The formulation of a one-dimensional model for the simultaneous evaluation of hydrodynamics and mass transfer in bubbly flow is presented in detail. The mass transfer due to the solubility kinetics and psychrometric aspects of the process is evaluated while accounting for the effects of process temperature and salinity of the liquid phase. While developed for downward co-current bubbly flow, the predictions of the model show good agreement with experimental data found in the literature for co-current upward bubble column. Using the model, the predicted profiles of pressure, temperature, liquid velocity, slip velocity, species' gas-phase molar flow rate along the axis of the pilot HAC downcomer under selected scenarios are presented. Modelling of the pilot and demonstrator scale HAC downcomers suggest that the psychrometric aspects of the compression process will be the determining factor for selecting HAC operating temperatures. Modelling of gas absorption in aqueous electrolyte solutions suggest that an intent to reduce gas solubility may be defeated due to the reduction of bubble size and the resulting increase in interfacial area. Initialisation of liquid phase concentrations of gas species are discussed with simulations showing the diminishing absorption rate with repeated cycles of gas compression when no gas is removed. The potential impacts on the applications of compressed air production and carbon capture are also discussed. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study presents a one-dimensional model for evaluating the hydrodynamics and mass transfer in bubbly flow. The model considers the effects of temperature and salinity on mass transfer due to solubility kinetics and psychrometric aspects. The predictions of the model are validated with experimental data and the potential impacts on compressed air production and carbon capture are discussed.