Work

Cleaning of a soluble soil layer by flow over a flat surface: an example of a Stefan-Graetz problem

Year: 2025

Type: article

Abstract: The cleaning of a soluble soil layer by the flow of solvent is an important example of a moving boundary problem coupled with a non-linear flux distribution. Removal of a model dissolving soil, a soluble coffee extract, from flat stainless steel plates by the passage of cold water was investigated experimentally in two geometries: ( i ) a long rectangular duct where the flow is turbulent and well developed, and ( ii ) a radial flow cell with Reynolds numbers < 1000, where the flow is laminar and steady (but not simple). Cleaning was quantified as the time to remove the soil and was found to be strongly location dependent, owing to the moving front, which was compounded further in ( ii ) owing to the non-uniform mass flux profile in this geometry. Cleaning in the rectangular duct featured striations associated with periodic turbulence patterns, while two cleaning fronts were observed in the radial flow cell owing to the presence of recirculation zones. A framework for computing the local cleaning time is presented which shows that neglecting the moving boundary nature of the problem can result in large overpredictions of cleaning times. Detailed simulations of mass transport were used to estimate local cleaning behaviour, with velocity fields calculated by CFD and diffusion coefficients obtained from separate experiments. The results showed good agreement with the experimental values.

Source: Chemical Engineering Science

DOI: 10.1016/j.ces.2025.122829

Authors: K.P. Deshmukh, A.T. Bagdziunas, R.S. Cant, D. Arlov, D.I. Wilson

Institutions: University of Cambridge, Tetra Pak (Sweden)

Language: English

Topic: Heat and Mass Transfer in Porous Media

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

SDG: Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $4,050