Effects of passage divider and packed brass beads on heat transfer characteristic of the pin-fin heat sink by water cooling

In this study, a design of an aluminum alloy pin-fin heat sink with the passage divider and the packed brass beads was proposed. The effects of the passage divider and packed brass beads on the overall heat transfer performance of the pin-fin heat sink under forced convection with water cooling was investigated experimentally. The heat sink is made of an aluminum alloy square cavity with the in-line square pin fins as the basic configuration. Among them, the number of pin fins (4 × 4, 3 × 3, 2 × 2, 0 × 0) and the height of pin fins (H = 5, 10, 20 mm) are variables. The filled brass beads have three particle sizes (d = 4, 6 and 8 mm), and the passage divider designs are divided into 2 types, namely, left-and-right S-shape divider and up-and-down S-shape divider. The results indicate that for the heat sink with the passage divider but no filled with brass beads, the passage divider has a significant heat transfer enhancement for the 4 × 4 and 3 × 3 pin-fin heat sink. Especially for the 3 × 3 pin-fin heat sink added with the up-and-down S-shape divider, the heat transfer enhancement is up to 60%. For the heat sink with the passage divider and filled with brass beads, when adding the same passage divider, compared with the test case without filled with the brass beads, the filling of brass beads (d = 4 mm) has a significant heat transfer enhancement for the heat sink with H = 5 and 10 mm. It increases the heat transfer by an average of about 14%. Therefore, in the test case, the 3 × 3 pin-fin heat sink (H = 10 mm) added with the up-and-down S-shape divider and filled with brass beads (d = 4 mm) has the most significant heat transfer enhancement, and the overall Nusselt number increases by about 65% compared with the heat sink without the passage divider and brass beads.