Conjugate Heat Transfer Study of Innovative Pin-Fin Cooling Configuration

The study involves experimental and numerical heat transfer analyses of four pin-fin cooling configurations in a rectangular channel. Two design concepts were studied with two separate pin-fin (cylindrical and triangular) geometries. The first design includes a single-walled pin-fin (D = 1.5mm) configuration (PF and TF) where the coolant flows through an array of full length (H/D = 1.33) cylindrical and triangular pin-fins. The second configuration involves a double-walled pin-fin-jet configuration (PFC jet and TFC jet) where the coolant jet impinges on the target wall, then flows through the array of partial length (G/D = 0:4) pin-fins. Infrared (IR) thermography was used to measure the wall temperature of the target surface to estimate the overall cooling effectiveness (phi). A transient heat transfer experiment was conducted to evaluate the internal heat transfer coefficient from the transient wall temperature. It is found that the double-walled pin-fin-jet configuration shows higher cooling effectiveness compared to the single-walled pin-fin design. The triangular pin-fin (TF) showed a higher heat transfer augmentation compared to the cylindrical pin-fin (PF) design. Numerical study later confirmed that the triangular pin-fin creates a pair of streamwise vortices that augments the local heat transfer. The presence of the pin-fin in the double-walled configuration prevents the development of a strong crossflow that negatively affects the heat transfer of the impinging jet. In addition, the triangular pin-fin not only prevent the strong crossflow, but redirects the coolant in the lateral direction that eventually contributes to the formation of a counter rotating vortex pair (CRVP) in the streamwise direction thus augments local heat transfer and improves overall cooling effectiveness. Pressure drop measurement showed that the full length triangular pin-fin has a higher pressure loss but the partial length pin-fin can lower the pressure loss considerably without compromising additional cooling performance.