6533b825fe1ef96bd12829c6

RESEARCH PRODUCT

Mass transfer in ducts with transpiring walls

M F La CervaLuigi GurreriM. Di LibertoGiorgio MicaleMichele CiofaloL. Scelsi

subject

Fluid Flow and Transfer ProcessesSettore ING-IND/26 - Teoria Dello Sviluppo Dei Processi Chimicibusiness.industryMechanical EngineeringSchmidt numberFlow (psychology)02 engineering and technologyMechanicsComputational fluid dynamics021001 nanoscience & nanotechnologyCondensed Matter Physics01 natural sciencesSherwood number010305 fluids & plasmasMass transfer Transpiring wall Sherwood number Computational fluid dynamics Parallel flowMass transfer0103 physical sciencesDiffusion (business)0210 nano-technologybusinessSaturation (chemistry)Settore ING-IND/19 - Impianti NucleariDimensionless quantityMathematics

description

Abstract The problem of mass transfer in ducts with transpiring walls is analysed: the concepts of “solvent” and “solute” fluxes are introduced, all possible sign combinations for these fluxes are considered, and relevant examples from membrane processes such as electrodialysis, reverse osmosis and filtration are identified. Besides the dimensionless numbers commonly defined in studying flow and mass transfer problems, new dimensionless quantities appropriate to transpiration problems are introduced, and their limiting values, associated with “drying”, “desalting” and “saturation” conditions, are identified. A simple model predicting the Sherwood number Sh under all possible flux sign combinations is derived from the single simplifying assumption that concentration profiles remain self-similar (so that the Sherwood number based on diffusion only remains unchanged) also under transpiration conditions. The simple model provides not only local values of Sh, but also its axial profiles. Predictions are validated against fully predictive CFD results, not based on the above simplifying assumption, and a good agreement is demonstrated provided the transpiration rate complies with certain limitations, depending on the Schmidt number.

yearjournalcountryeditionlanguage
2019-04-01International Journal of Heat and Mass Transfer
https://doi.org/10.1016/j.ijheatmasstransfer.2018.12.059