Modelling turbulence and thermophoresis in plate heat exchanger with high solid content

CATEGORY: HEAT EXCHANGERS
Proceedings of International Conference on Heat Exchanger Fouling and Cleaning, June 9-14, 2013, Budapest, Hungary
Modelling turbulence and thermophoresis in plate heat exchanger with high solid content
U. Ojaniemi (1), M. Manninen (1), T. Pattikangas1 and M. Riihimaki (2)
1 VTT Technical Research Centre of Finland, VTT, Finland
2 Mass and Heat Transfer Process Laboratory, Dept. of Process and Environmental Engineering, University of Oulu, Oulu, Finland
Abstract
Particulate fouling of plate heat exchangers is studied using a multiphase computational fluid dynamics (CFD) approach based on the algebraic slip mixture model.
Particulate fouling is a serial process of transport of particles into a vicinity of the surface than adherence on the surface. Turbulence is generally considered to be the main reason for resuspension of the adhered particles. The suitability of different turbulence models for describing the shear forces at wall when modelling fouling is investigated. CFD simulations of a test heat exchanger were performed with standard κ-ε turbulence model with enhanced wall treatment (EWT) in 2D and 3D. Large Eddy Simulations 9LES) in 3D were performed and compared to the κ-ε model results. The calculated results were compared with the experimental data for deposition rate of colloidal calcium carbonate particles and with the results simulated with the CFD model for particulate fouling presented earlier by Ojaniemi et al. The earlier model incorporated the drag and diffusion forces affecting on the particl transport in the near-wall region into the wall function approach. Here the model has been further developed to include the effect of thermophoresis.  Several models presented in literature for the Sore coefficient are compared.
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