Intensifying CO2 condensation in the flue gas through the supersonic separators by hydrogen enriching: A computational study

The presence of carbon dioxide in combustion products is one of the main reasons for global warming. Supersonic separation is a modern, eco-friendly, and cost-efficient technology for capturing carbon dioxide. In this study, the physics of CO2 condensation through a supersonic separator nozzle for purifying the flue gas mixture is modeled using a numerical programming method based on the finite volume AUSM scheme. A limiting maximum for condensation efficiency relative to the CO2 content in the flue gas was demonstrated for fixed inlet conditions. The idea of enhancing the carrier gas heat capacity by hydrogen enriching for promoting droplet formation and condensation of CO2 in the mixture is being studied for further increasing condensation efficiency. The analysis uses the Peng-Robinson equation of state formulation, the multi-diameter growth model appropriate for the Eulerian-Eulerian problem, and the nucleation model suitable for high-speed mixture flows. The results show that adding about 48 % molar fraction of hydrogen increases the growth of droplet and condensation efficiency about 1.3 and 1.5 times, respectively. This technique can significantly increase the separation efficiency in supersonic separators.