Thermal performance investigation of a plate fin heat sink equipped with twisted tape and perforated twisted tape

The concept of heat transfer enhancement in a plate fin heat sink (PFHS) using twisted tape is presented. The airflow behavior in the flow channel and heat sink performance are investigated at the Reynolds numbers between 2000 and 5000. The twisted tape and perforated twisted tape with twist ratio between 2.5 and 3.5 are equipped between the fins of the PFHS. For perforated twisted tape, the holes are drilled along the twisted tape length with the ratio of perforation diameter to twisted taped width (d/W) between 0.2 and 0.6. The heat transfer coefficient and pressure drop are enhanced by decreasing the twist ratio and increasing the Reynolds number and the d/W ratio between 0.2 and 0.4. However, they are dropped when the d/W ratio higher than 0.4. The highest thermal performance factors of the plate fin heat sink equipped with twisted tape (PFHSTT) and the plate fin heat sink equipped with perforated twisted tape (PFHSPTT) are 1.28 and 1.33, respectively. The correlations of the Nusselt number and friction factor related to twist ratio and d/W ratio are generated and proposed for designing and selecting in the future. between perforation thermal performance. the impact of the plate the performance of a PFHS. the air bypass the of a good a of the performance of PFHS with different fin forms of sinks. The a frontal a test section and releasing to the ambient air. The wind tunnel was made from a 5-mm thick acrylic plate. The rectangular flow channel had a width of 27 mm, a height of 25 mm, and a length of 1.0 m. A 4.5-inch axial fan, which was controlled with an inverter, was installed at the tunnel entrance. The honeycomb (straightener) was used to eliminate the twisted airflow from the entrance before entering the PFHS. The hot wire anemometer monitored the airflow velocity inside the wind tunnel. To simulate the actual working conditions, the heat sink base was placed on the plate heater surface, which was used as a heat source. Silicone thermal grease was coated on the heater surface to reduce thermal contact resistance. The variable voltage transformer adjusted the supplied heat flux from a 100 W plate heater. The heater was embedded in a Bakelite rectangular rod with a 65-mm width, 65-mm height, and 120-mm length, and the wind tunnel was covered by 10 mm of insulation. To read the temperature of airflow at the PFHS’s entrance and exit, five T-type thermocouples were installed at the center of the flow channel. Two thermocouples were placed before the heat sink at distances of 20 and 40 mm. Similarly, three thermocouples were located after the heat sink at distances of 20, 40, and 60 mm. Four thermocouples were positioned at 1 mm below the base surface to measure the average surface temperature. The distance between thermocouples along the heat sink length was 15 mm. The data logger connected to the computer recorded all temperatures obtained from the thermocouples. A digital manometer logged the pressure difference across the heat sink. To ensure precision and reliability, the instruments were calibrated, and the experimental data was collected under steady-state conditions. performance