Thermo-fluids performance analysis and experimental verification of topologically optimized mini-channel heat sinks integrated with impact jet

Abstract

Mini/micro-channel heat sinks with integrated impact jet offer significant potential for enhanced heat transfer performance. In this work, jet structures are integrated with four-inlet-two-outlet horizontal-flow heat sinks and the thermo-fluids performance is discussed. At first, four horizontal-flow heat sinks with diverse distributions of inlets and outlets locations are designed, using variable density topology optimization method with the minimization of average temperature and pressure drop as optimization objective. Among them, three are symmetric structures and one is asymmetric. Numerical simulations are conducted on the thermo-fluids performance of these four designs across six channel heights $H_m$. The designs of MHS-A and MHS-B exhibit the highest cooling efficiency factor $j_c$ and best flow performance, respectively. In addition, the comprehensive performance evaluation of the asymmetric structure MHS-D is not the worst. Subsequently, a jet structure was integrated above the original horizontal flow path so that the vertically oriented fluid impinges on the horizontal flow path, forming the new cross-flow radiators IJMHS-A and IJMHS-B. Numerical results indicate that at a volume flow rate of 1152 ml/min and a jet ratio of 20 %, the average temperatures, maximum temperatures and temperature differences of IJMHS-A and IJMHS-B are reduced by 4.8 K, 6.8 K, 3.7K and 7.6 K, 10.8 K, 7.3K, respectively. A slight pressure drop loss is observed only for $H_m\ge 3mm$. The jet's gain of thermal performance decreases with increasing volume flow rate, displaying boundary effects. As the jet flow ratio rises, thermal performance initially improves, then declines, while the pressure drop increases at an accelerated rate. Optimal interval of the jet flow ratio is structure-dependent. For IJMHS-A and IJMHS-B, the best performance occurs with a jet flow ratio between 10 % and 30 %, combining benefits of both horizontal-flow topology and jet-flow structures. As the jet ratio continues to rise, the flow shifts from horizontal to jet characteristics, rapidly degrading heat transfer and flow performance. Numerical simulations are verified, aligning well with experimental results.