Abstract
Power electronic devices like Insulated Gate Bipolar Transistors (IGBTs) and diodes are often characterized by power densities and dimensions that could result in very high heat flux densities. In order to guarantee the expected performance and lifetime for these components, dedicated active cooling devices are usually adopted. In the present paper, the comparison between two different cooling strategies for power electronics is presented: fractal-channel design and submerged impinging jets. Each cooling strategy is tested on two different geometrical configurations. Water is used as coolant in all cases. Assessment of the considered cooling methods is done through application of the selected configuration in a simplified system composed by a rectangular chip (heat source) separated from the coolant by a solid block.Three-dimensional conjugated heat transfer simulations are performed by using RANS solver implemented in OpenFOAM and two-equations turbulence models, resolving also the viscous sublayer. Numerical results allow to compare the cooling strategies in terms of maximum chip temperature, overall chip-to-coolant thermal resistance, and pumping power required. In summary, the fractal-channel design shows limitations in guaranteeing low chip temperatures at an affordable pumping power. The submerged impinging jets approach shows very high local heat transfer coefficient by which it is possible to tailor the cooling effect on specific hot spots.
Highlights
Heat removal from power electronic devices is a technical problem common to many industrial fields, including the recent application of power electronics to hybrid traction systems
Power electronic devices like Insulated Gate Bipolar Transistors (IGBTs) and diodes are often characterized by power densities and dimensions that could result in very high heat flux densities
This study investigates and compares two single-phase liquid cooling devices for a single chip: the first one employs a network of fractal channels while the second one uses an array of submerged impinging jets
Summary
Heat removal from power electronic devices is a technical problem common to many industrial fields, including the recent application of power electronics to hybrid traction systems. [1], it is demonstrated that a tree-shaped structure increases its heat transfer capabilities and decreases its pumping power request for larger number of fractal levels. Results show the improvements of tree-shaped structures in heat transfer efficiency and pressure drop reduction. [3], tree-shaped nets on a square chip are investigated and compared to straight and serpentine networks . Parallel channels having a constant cross section show better cooling efficiency than fractal ones. From this brief literature survey, it appears clearly that tree-shaped channels have a good potential but their performance can depend strongly on the specific application. In the present paper the crucial importance of the ratio between wet surface and heat transfer area in tree-shaped channels is discussed
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