Numerical study on carbon dioxide capture in flue gas by converging-diverging nozzle

To combat global warming, reducing the emission of CO2 greenhouse gas which mainly comes from the flue gas produced by the burning of fossil fuels remains a top priority. In order to study the possibility of convergingdiverging nozzle capturing CO2 in flue gas, a mathematical model of N2-CO2 condensation flow (the main component of flue gas after desulfurization, denitration and drying) is established, in which N2 is carrier gas and CO2 is condensable gas. By adding transport equations and source terms to describe the relationship between gas and liquid phase, the complex heat and mass transfer process in supersonic compressible condensation flow can be accurately predicted. In order to investigate the influence of non-equilibrium condensation on the flow behavior, the single-phase flow is compared with the condensation flow. The results show that the single-phase flow model overestimates the gas expansion characteristics. Weak condensation shock occurs in the nonequilibrium condensation process, which leads to the decrease of the cooling performance of nozzle. In addition, the distribution characteristics of condensation parameters in non-equilibrium state are clarified. It is found that supersonic technology is a possible carbon capture method. The reliability of condensation flow model is proved by theoretical analysis and experimental validation.