Effect of symmetry of branching on leaf-like flow channel

• Main Author: Huang, Zhiwei
• Other Authors: Ooi Kim Tiow
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/71527
• Institution: Nanyang Technological University

Microchannel heat sinks are effective for heat dissipation, however, it comes with high fabrication cost. For this experiment, the microchannel effect is created by superimposing macro geometries, which can be manufactured using readily available machining methods at a much lower cost. While the heat enhancement is superior in the microchannel, the pressure drop is undesirable. In an attempt to reduce the change in pressure, leaf venation designs inspired by naturally existing flow systems are considered for the experiment. This study aims to examine the effect of symmetry of branching in a leaf-like network on pressure drop and heat transfer performance. Experiments are carried out for single-phase steady state forced convection heat transfer with distilled water as the working liquid for Renyolds number of 1400 to 4600. Results suggest that local effects caused by surface profiles are insignificant to the heat transfer performance of the inserts. Maximum percentage difference in terms of Nu for the same Re is 12.2% across all the enhanced microchannels while the experimental uncertainty is 12.8%. It is also revealed that at the same pumping power, although all inserts with leaf-like flow channels are able to remove more heat than the plain one, different surface profiles of the inserts feature different hydrodynamic performance. Enhanced microchannel profiles with smaller branching angles produce a 15.91% higher pressure drop while symmetric Leaf designs incur lower pressure drop of 32.73% as compared to asymmetric designs. At maximum Reynolds number of 4000, Leaf65 has a pressure drop value of 2.58 bars as compared to the ALeaf65 insert with a value of 2.98 bar.