Thermal and hydraulic behavior of plate fin and strip fin heat sinks under varying bypass conditions

Tests have been conducted in a wind tunnel with nine heat sinks of three different types including plate fin heat sinks and strip fin heat sinks arranged in both in-line and staggered arrays. For each type, tests were run with fin heights (H) of 10, 20 and 30 mm while the heat sink width (B) was kept constant and equal to 52.8 mm. The width of the wind tunnel duct (CB) was varied in such a way that results were obtained for B/CB = 0.84, 0.67, and 0.33. The wind tunnel height (CH) was varied similarly, and data were recorded for H/CH = 1, 0.67, and 0.33 while the duct Reynolds number was varied between 2000 through 14000. An empirical bypass correlation has been fitted to the experimental data. Generally, the agreement between experimental data and correlation is within +/- 10 % for the thermal resistance, and within +/- 20 % for the pressure drop. From the experimental data, the fraction of the total airflow passing through the heat sink have been estimated and are compared to a simple physical bypass model.