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Proceedings of an International Conference on Mitigation of Heat Exchanger Fouling and Its Economic and Environmental Implications

ISBN Imprimer:
1-56700-172-6

THEORETICAL STUDY OF PARTICLE DEPOSITION ONTO A CYLINDER IN CROSS-FLOW

A. K. Temu
Department of Chemical and Process Engineering, University of Dar Es Salaam, P. O. Box 35131, Dar Es Salaam, Tanzania

Erling Naess
Department of Energy and Process Engineering, Norwegian University of Science and Technology, N-7491 Trondheim, Norway

Otto K. Sonju
Department of Energy and Process Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway

Résumé

A two-dimensional computational scheme for simulating particle dispersion and deposition onto a cylinder in cross-flow was developed. RNG k-ε model was used to simulate the mean turbulent flow fields. The computational model predictions for particle deposition velocity between parallel plates showed good agreement with an empirical correlation befitting such geometry. Qualitative comparison showed that thermophoretic effect is more pronounced in duct flow than in cross-flow. For Stokes number, Stkc > 0.1 simulation results for a cylinder, rectangle and trapezoid in cross-flow are in good agreement. For Stkc < 0.1 geometry of the obstacle and turbulence effect play significant role in the net deposition. Simulations with constant particle size showed all the three deposition regimes by just varying the fluid velocity. Diffusion and residence time of the particle might explain this. Comparison of the results with some experimental results, for the similar geometry, is discussed in a companion paper.