Oblique fluid flow and heat transfer across a hollow fiber membrane bank under uniform temperature conditions

• Oblique flow and heat transfer across a hollow fiber membrane bank is studied.
• Impinging angles change from 0 to 90°.
• Correlations for friction and Nusselt numbers are proposed with varying angles.
• Performance for skewed flow is in the middle between cross flow and parallel flow.

Hollow fiber membrane banks have been extensively used in various energy and environmental technologies. Fluid flow and heat and mass transfer in the tube bank have been a focus of study. Previous researches have been focused on either pure parallel flow or pure cross flow. However they are only very ideal flow conditions. This study addresses a more common condition: oblique flow, in which shell side flow impinges the fiber tubes with a skew angle. By solving the fluid flow and heat transfer equations in the shell side, convective coefficients are obtained for impinging angles from 0° to 90°. It is found that the oblique angle influences the heat transfer properties seriously. Heat transfer rates for oblique flows are higher than those for parallel flows but lower than those values for cross flows. Correlations are proposed for the prediction of friction factors and Nusselt numbers at various oblique angles, both for aligned and staggered arrays with various geometrical parameters. Then mass transfer coefficients can be obtained from the calculated Nusselt numbers with heat-mass analogy.

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