Low flow-rate required thermal management of dual chips with large heat flux

Abstract

Microchannel heat sinks with the advantages of impingement jet and pin-fins (MCHS-Js) have been proposed for cooling dual hotspots with high heat flux (heat power of 30 W and heat flux of 200 W/cm² for each), which is the basic unit of compact electronic equipment with discrete hotspots. Based on numerical simulation, the thermo-hydraulic performance and heat transfer mechanisms of MCHS-Js under extremely low flow rates (3 L/h-8 L/h) are conducted. Compared with rectangular fin microchannel (MCHS), MCHS-Js can reduce the maximum temperature of the hotspots by 14.8 K and 8.3 K at the flow rate of 3 L/h and 8 L/h, respectively. MCHS-Js with the jet holes arranged in diamond shape can keep the maximum temperature difference of dual chips within 5.6 K when the flow rate is 8 L/h, which is 21 % lower than that of MCHS. And MCHS-Js can achieve lower thermal resistance with lower flow rates, which contributes to the energy saving of cooling system. Then a comparison with the previously published microchannel heat sinks highlights the advantages of MCHS-Js in low flow-rate conditions, and the energy consumption ratio is only 0.2 %. The mechanism analysis shows that for the same mixing chamber connected to the outlet, the channel width of the hotspot far from the inlet should be larger to reach the best temperature uniformity, generating more intense impingement jet to the hotspot. Meanwhile, the heat transfer capacity of target surface can be weakened by cross flow deflection, while the heat transfer efficiency of pin-fins can be improved by longitudinal vortices. These rules are of great significance for the design of compact heat sinks.