Impinging jets confined by a conical wall - high Schmidt mass transfer predictions in laminar flow

Mass transfer from a soluble plate to an impinging liquid jet confined by a conical wall is investigated. The nozzle-to-plate distance is very short, less than one nozzle diameter, the flow regime is laminar, Re < 1600, and the Schmidt number ranges from 960 to 50000. Navier-Stokes and solute transport equations are solved by a finite difference scheme. Numerical predictions of the average mass transfer coefficient are compared with data obtained by measuring the dissolution rate of benzoic acid in water and in aqueous solutions of glycerol. A correlation is presented between stagnation Sherwood number, jet Reynolds number and Schmidt number, Sh(gt)/Sc-1/3 = 1.77(1/2). The effects on the mass transfer coefficients of the velocity profile at the nozzle exit and of an insoluble starting length are analyzed. The onset of laminar-to-turbulent transition is identified using mass transfer data. The mass transfer coefficients in the conical cell are compared with those in a radial cell confined by parallel plates. (C) 2001 Elsevier Science Ltd. All rights reserved.