EFFECT OF MICRO-FIN GEOMETRY ON LIQUID HEAT TRANSFER RATE AND PRESSURE DROP

The conventional method of increasing heat transfer rate in liquid flow is to use extended surfaces or fins. Current practice for water-based systems is to use small trapezoidal micro-fins (< 0.5 mm tall) on heat exchange surfaces. Although the use of fins are beneficial for thermal performance, the added weight of material leads to higher costs for bulk commercial products and the increased pressure drop adds to the products operational cost. The fin changes the local surface area, local flow patterns, and local heat transfer coefficient in a complex manner. Current practice is to ignore the influence of fin shape on surface performance. The current study investigates the influence of design parameters such as fin geometry and angle to flow direction on heat transfer performance with a constant fin volume. A coupled numerical simulation of the flow and solid domains with periodic boundaries were setup in ANSYS Fluent software. Performance was mapped for a constant fin cross sectional area for four different fin geometries (rectangular, trapezoidal, triangular, and parabolic). A total of nine (one smooth duct and eight micro-fin ducts) scenarios were considered in which turbulent flow was dominant and Reynolds number was about 15,400. Results show the maximum heat transfer and minimum pressure drop along the fin belongs to a transverse rectangular micro-fin to flow direction. Total fin performance can increase to 15 % from the worst to the best design by changing design parameters.