Numerical and experimental investigation on water vapor condensation in turbulent flue gas

Abstract

Because the identical gradient is only in the immediate vicinity of condensation interface, there is the restriction of grids refinement in previous models for computational fluid dynamics (CFD) simulations of turbulent flue gas condensation. To overcome this limitation, this paper proposed a condensation model expanded by the law-of-the-wall for species based on y*. The model employed a mass sink at wall-adjacent gaseous cells and an energy source at opposite wall-adjacent coolant cells. The numerical results were in good agreement with the measurements acquired form the laboratory scale tests of flue gas condensation using staggered tube bundle heat exchangers. In addition, the comparisons with previous condensation models were performed under the same mesh. The results showed a serious degradation in the prediction accuracy compared to present model, e.g. the maximum errors of the predicted condensate mass rate increased from 5.5% to 25.3% and 23.3%. It is completely acceptable to ignore the effect of Stefan flow in simulations of flue gas condensation with the water vapor volume fraction below 16%.