Development and optimization of jet impingement on dimpled plate for maximizing cooling performance of an inverter

A need to develop a cooling method with high cooling performance like jet impingement is increased as high power of an inverter is required. Jet Impingement on the dimpled plate would increase thermal performance than that of flat plate. Many previous researchers have dealt with the multi jet impingement on flat plate and some results of the study on dimpled plate evaluate the effect on heat transfer coefficients on several limited cases, making it difficult to apply them to inverter designs. Therefore, in this paper, heat transfer performance, pressure drop, and robustness at micro-scale of jet impingement on the dimpled plate were investigated in detail and the correlations of each performance were proposed. Finally, the optimal design was presented. The cooling performance was influenced by the jet array and the effect of depth and width of the dimples. The former can be expressed in terms of the Reynolds number, the ratio of height to nozzle diameter(H/D), the ratio of pitch to diameter(S/D). The latter can be expressed in terms of the ratio of dimple depth to dimple diameter(t/Dd) and the ratio of dimple width to pitch(SD/S). Although the heat transfer coefficient of the shallow dimple is larger than that of the deep dimple, the heat transfer coefficient decreases when the width of the dimple becomes too wide. The correlations were proposed and presented to the characteristics of heat transfer depending on jet array and the dimple. Uncertainty was introduced to evaluate the robustness. The optimal design was derived by swinging variables based on the correlations and considering the robustness of performance maximizing heat transfer under pressure drop below 300mbar. Compared to the base design, the thermal resistance of optimum design was improved by 6.0% from 0.2350K/W to 0.2210K/W. The correction-based optimization results were consistent with the 3D CFD results.