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.
Ciofalo, M., Di Liberto, M., Gurreri, L., La Cerva, M., Scelsi, L., Micale, G. (2019). Mass transfer in ducts with transpiring walls. INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, 132, 1074-1086 [10.1016/j.ijheatmasstransfer.2018.12.059].
Mass transfer in ducts with transpiring walls
Ciofalo, M.
;Di Liberto, M.;Gurreri, L.;La Cerva, M.;Scelsi, L.;Micale, G.
2019-01-01
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.File | Dimensione | Formato | |
---|---|---|---|
Ciofalo et al. - 2019 - Mass transfer in ducts with transpiring walls.pdf
Solo gestori archvio
Descrizione: published paper
Tipologia:
Versione Editoriale
Dimensione
2.75 MB
Formato
Adobe PDF
|
2.75 MB | Adobe PDF | Visualizza/Apri Richiedi una copia |
self-archived_versionIJHMT2019_Ciofalo_et_al.pdf
accesso aperto
Descrizione: self-archived version of the paper
Tipologia:
Pre-print
Dimensione
2.21 MB
Formato
Adobe PDF
|
2.21 MB | Adobe PDF | Visualizza/Apri |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.