Experimental and Numerical Study Upon Uniformity of Impingement Cooling With Pin-Fin Heat Sink

Abstract

In this paper, the impingement cooling performance on pin-fin heat sinks is experimentally and numerically investigated with different outlet arrangements and pin-fin layouts. Compared with one-way opening arrangement, results show that the two-way opening arrangement can offer a much lower pressure loss ( $\Delta p$ ) due to shorter flow distance of airflow from outer jets. Meanwhile, it is surprising that the two-way opening arrangement still offers appreciable improvements on effective heat transfer coefficient ( $h_{\mathrm {eff}}$ ). This is because the fountain may shift toward the outer jets more rapidly with one-way opening arrangement. Yet the implementation of staggered pin-fin layout has minor improvement on $h_{\mathrm {eff}}$ . However, $\Delta p$ can be obviously reduced by 11.1% due to the more effective spreading of impinging airflow in radial direction. The $h_{\mathrm {eff}}$ value can be further increased by 8.8% when a smaller jet-to-target distance is applied. With priority consideration of hot spots in electronic cooling, the nonuniformity of local Nusselt number ( ${S}$ ) is further studied through the computational fluid dynamics (CFD) method. ${S}$ approaches 18.5% when the airflow directly impinges on a flat surface with optimized jet array. Implementing pin-fin heat sinks can reduce the nonuniformity of Nusselt number distribution to fall below 8.0%. The nonuniformity of local Nusselt number can be further reduced to 1.8% by applying four-way opening arrangement and larger central jet at the same time.