Comparison of technologies and preliminary feasibility study for the optimal thermal management of a power electronics module

The increasing integration of power electronics in aerospace and defence applications presents significant challenges in terms of thermal management, due to the high power densities and stringent reliability requirements. The rise in power densities and the use of compact, high-performance components necessitate cooling systems that can effectively dissipate generated heat while ensuring reliability, a lightweight design, and compliance with the strict dimensional and operational constraints typical of these applications. This thesis presents a comparative analysis and a preliminary feasibility study of two advanced cooling technologies aimed at optimizing the thermal performance of power electronics modules. The work is structured in two main phases. Initially, a thorough review of the scientific and industrial state of the art was conducted, including direct and indirect contact cooling strategies and heat spreaders such as heat pipes and vapour chambers. This review led to the identification of two promising configurations for further development in the case study: liquid minichannel and liquid Triply Periodic Minimal Surfaces (TPMS) based cooling systems. The second phase starts with the development of the minichannel cooling system. Using Solid Edge, detailed CAD models of the module were created and simulated in Simcenter FLOEFD to assess both thermal and hydraulic performance. Three different methodologies were followed to determine the geometric properties of the minichannels cold plate. Firstly, an analytical process based on thermodynamic principles was applied. Secondly, an objective function was used, specifically created for this purpose. Furthermore, a multi-objective optimization was applied using MATLAB, specifically the Multi-Objective Genetic Algorithm-II (MOGA-II) algorithm, to explore multi-objective trade-offs. The TPMS cooling system was designed similarly to the minichannels. TPMS geometries were created using Altair Inspire, accurately representing their complex lattice structures through implicit modelling. The structure analysed was the TPMS Gyroid, and its geometric characteristics were determined following indications found in the literature. Once the TPMS unit cells were created, an evaluation of their thermal and hydraulic properties was conducted using Simcenter FLOEFD. These properties were then used in the porous media tool of Simcenter FLOEFD to extend them to the full porous medium structure, not just the unit cell. The results show the strong potential of the minichannel system to achieve efficient dissipation, with the best performing configuration obtained via MOGA-II, achieving an average temperature reduction of 23% compared to the reference setup. Other configurations, using analytical and objective function methods, also showed significant improvements, around 18 and 19%, confirming the strength of the approach. All minichannel designs led to a notable increase in hydraulic resistance, although pressure drops remained within acceptable design limits. Furthermore, the minichannels exhibited excellent temperature uniformity throughout the module. The TPMS-based solution achieved a comparable 19% temperature reduction with significantly lower impact on hydraulic performance, making it a promising solution where pressure drop constraints are stricter. Although the study is preliminary, it lays the groundwork for more in-depth research and has already attracted positive attention within the industrial context in which it was developed.