University of Oulu

JOHNSEN, S.G., PÄÄKKÖNEN, T.M., JOHANSEN, S.T., KEISKI, R.L. and WITTGENS, B., 2017. Implementation, demonstration and validation of a user-defined wall function for direct precipitation fouling in ansys fluent, J.E. OLSEN and S.T. JOHANSEN, eds. In: International Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries 2017, SINTEF Proceedings, pp. 717-725.

Implementation, demonstration and validation of a user-defined wall function for direct precipitation fouling in ANSYS fluent

Saved in:
Author: Johnsen, Sverre G.1; Pääkkönen, Tiina M.2; Johansen, Stein T.1,3;
Organizations: 1SINTEF Materials and Chemistry, NO-7465 Trondheim, NORWAY
2University of Oulu, Environmental and Chemical Engineering, FI-90014 Oulu, FINLAND
3NTNU, Dept. of Energy and Process Engineering, NO-7491 Trondheim, NORWAY
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.7 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe201706016966
Language: English
Published: SINTEF Academic Press, 2017
Publish Date: 2017-06-01
Description:

Abstract

In a previous paper (Johnsen et al., 2015) and presentation (Johnsen et al., 2016), we developed and demonstrated a generic modelling framework for the modelling of direct precipitation fouling from multi-component fluid mixtures that become super-saturated at the wall. The modelling concept involves the 1-dimensional transport of the fluid species through the turbulent boundary layer close to the wall. The governing equations include the Reynolds-averaged (RANS) advection-diffusion equations for each fluid species, and the axial momentum and energy equations for the fluid mixture.The driving force for the diffusive transport is the local gradient in the species’ chemical potential. Adsorption mechanisms are not modelled per se, but the time-scale of adsorption is reflected in the choice of Dirichlet boundary conditions for the depositing species, at the fluid-solid interface.

In this paper, the modelling framework is implemented as a user-defined function (UDF) for the CFD software ANSYS Fluent, to act as a wall boundary condition for mass-transfer to the wall. The subgrid, 1-dimensional formulation of the model reduces the computational cost associated with resolving the fine length-scales at which the boundary-layer mass transfer is determined, and allows for efficient modelling of industry-scale heat exchangers suffering from fouling.

The current paper describes the modelling framework, and demonstrates and validates its applicability in a simplified 2D heat exchanger geometry (experimental and detailed CFD modelling data by Pääkkönen et al. (2012, 2016)). By tuning the diffusivity, only, good agreement with the experimental data and the detailed CFD model was obtained, in terms of area-averaged deposition rates.

see all

Series: SINTEF proceedings
ISSN: 2387-4295
ISSN-E: 2387-4295
ISSN-L: 2387-4295
ISBN: 978-82-536-1544-8
Issue: 2
Pages: 717 - 725
Host publication: Progress in Applied CFD – CFD2017 Proceedings of the 12thInternational Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries
Host publication editor: Olsen, Jan Erik
Johansen, Stein Tore
Conference: International Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries
Type of Publication: A4 Article in conference proceedings
Field of Science: 215 Chemical engineering
Subjects:
CFD
UDF
Funding: This work was funded by the Research Council of Norway and The Norwegian Ferroalloy Producers Research Association, through the SCORE project (Wittgens, 2013).
Copyright information: Published in this repository with the kind permission of the publisher.