MODELING OF MULTICOMPONENT DIFFUSION IN HIGH-TEMPERATURE FLOWS

Three methods for computing diffusive mass transfer in non-reactive hi gh temperature flows are compared. Results show that the widely used e ffective binary approximation may lead to large errors (up to 70%) in the evaluation of the mass fluxes, reflecting, therefore, on the solut ion of the species conservation equations. Two other approaches, the c onsistent effective binary diffusion due to Ramshaw, hereafter called the Ramshaw's approximation, and the linearized method are shown to re produce accurately the mass transfer obtained with the exact formulati on for multicomponent high temperature hows in isotherm conditions. Wh en temperature gradients are imposed, the linear approximation leads t o important errors (up to 40%) on the mass flux calculation. (C) 1997 Elsevier Science Ltd.