The novel efficient protrusion-rib configuration for increasing the temperature uniformity in multiple jet microchannel heat sink

Abstract

Multiple jets in microchannel heatsinks were introduced as a high-rate cooling methods. While temperature non-uniformity is a challenge in this method. The synergistic effects of the simultaneous presence of rib and protrusion on the performance of multiple jets in a micro channel heatsink are investigated. In order to increase the temperature uniformity and heat transfer rate, the protrusions are created on the target wall and in order to control the cross flows, the ribs are created on the jet wall. Therefore, Four configurations of microchannel are studied including: without rib and without protrusion (Case-a), only with rib (Case-b), only with protrusion (Case-c) and with rib and with protrusion (Case-d). A 3D numerical model is created to study the microchannel heatsink thermal performance for incompressible, steady-state, and turbulent regime. Thermal and hydraulic performance are evaluated by comparing Nusselt number, pressure drop and temperature uniformity for Reynolds numbers from 3000 to 7900. The study reveals that rib and protrusion effects, such as reducing the detrimental effects of cross flows, reducing jet flow deviation, creating the re-impinging jet phenomenon, and mixing more of the fluid, can improve jet-cooling performance. Case-d decreases the target wall temperature by 10.9 % compared to Case-a. At a Reynolds number of 5200, the Nusselt number of Case-d increases by 25.3 % compared to Case-a, 19.4 % compared to Case-b, and 7.3 % compared to Case-c. The simultaneous presence of rib and protrusion in Case-d has the best temperature uniformity. The study limits the device's surface temperature to 65 °C. The simultaneous presence of ribs and protrusions reduce the surface temperature from 61.7 °C to 56.2 °C from Case-a to Case-d. Additionally, the effect of different rib orientation angles is investigated. Reducing the rib angle from 90° to 45° increases the Nusselt number by 4 % and decreases the pressure drop by 11 %. The rib-45° enhances heat transfer rate and minimizes pressure loss. The performance evaluation criteria of the rib-45° is higher than the rib-60° and rib-90°.Finally, obtained outcomes reveals that the presence of rib-protrusion in multi-jet microchannel heatsink can improve the temperature uniformity significantly.