Investigation Of Heat Transfer Enhancement From Straight-fin Heat Sink Under Natural Convection

The heat sink is very common in electronic devices. Straight fin heat sinks are widely used because of the advantages of light weight, low cost, high heat transfer efficiency and easy extrusion molding etc. Natural convection of the straight fin heat sinks was studied in this article. The main contents are as follows:(1) A test bench was built to measure the thermal performance of heat under sink natural convection state. It was found that the experimental method of measuring the temperature at a given power has higher reliability, through the comparative analysis of the initial test, and chose it as the experimental method for the follow-up experiments.(2) Experimental and numerically investigation were carried out to study the thermal performance of heat sink under the influence of the installation angles. The thermal performance reaches the worst in the installation angle of 15°, while the best at 90°. The reason is that heat exchange between the air and fin surfaces occurs as the air enters the heat sink and flows along the fins. The air temperature gradually increased so that the temperature difference between the air and the fin surfaces is smaller as the air flows out the heat sink, which will form the heat transfer dead zone, reducing the effective heat dissipation area of the heat sink. The heat transfer dead zone occupies the largest proportion in the installation angle of 15°, that is, the effective heat dissipation area of heat sink is the smallest, and the thermal performance is the worst.(3) In order to verify the heat transfer dead zone and enhance the heat transfer, the corner portion of the heat sink was cut. It is found that appropriate chamfer size contributes to the heat dissipation of heat sink, but the chamfer size cannot be too large.(4) A slit in the middle of the heat sink under different installation angle can enhance the heat dissipation of heat sink, but its width cannot be too large. The thermal performance of the slotted heat sink reaches the best in the installation angle of 0°, regardless of the slit width. The effect that slotting strengthens the thermal performance of heat sink at a certain installation angle is gradually reduced, with the slit width increases. And it will weaken the heat transfer when the slit width is lager than 12 mm and the installation angle is lager than 30°.(5) As the slit width is 5mm, the number of slits affectes the thermal performance of split heat sink signicantly, and the thermal performance of every split heat sink reaches the best in the installation angle of 0°. As the slit number is 1, the thermal performance reaches the worst in the installation angle of 15° while it reaches the worst at 90° with the other slit numbers. The trend of thermal performance with the slit numbers changing is different at different installation angle. In the case that the installation angle is less than 45°, the thermal performance of split heat sink reaches the best in the slit number of 7. However, as the installation angle is lager than 45°, it will reach the best at 9.