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The carbon-free energy systems such as nuclear can benefit from compact and highly efficient heat exchanger technologies. The plate-type compact heat exchangers such as the printed circuit heat exchanger (PCHE) holds promise to fulfill these requirements. This work presents the thermal-hydraulic and structural analysis of PCHE for molten salt applications with thermal energy storage. In this study, three distinct types of geometry are chosen for the analysis, i.e., the zigzag channel type, the airfoil fin type, and the slotted fin type. For the working fluid, FLiBe (Li2BeF4) and solar salt (60% NaNO3 and 40% KNO3) are chosen for hot side and cold side, respectively. Titanium grade 5 is chosen as the structural material. The study is conducted by computational fluid dynamics (CFD) and finite element method (FEM) analysis. The thermomechanical behavior including pressure drop, fluid temperature, velocity profile, stress, and deformation of the flow channel were considered in this work. From the results, the zigzag channel geometry gives the best thermal hydraulic performance in terms of heat transfer and pressure drop. The structural analysis shows that the stress intensity has an exponential growth with power generation level with zigzag channel geometry being the highest out of three geometries. Overall, the zigzag channel PCHE is still the most suitable geometry for this application. Zigzag channel geometry should be substituted with an alternative geometry at a high-power application having both airfoil-fin and slotted-fin geometry at relatively identical stress intensity.

Multi-objective topology optimization (TO) has been adopted recently in the thermal-fluidic problem, resulting in cooling devices with non-intuitive and complex flow paths, yet revealing a significant improvement in the thermal performance. Although previous works utilized the multi-objective TO to design a cooling plate for the Battery Thermal Management Systems (BTMS), the effect of the heat loads from different charge/discharge rates on the optimized flow paths has not been fully assessed. Therefore, the present study implemented the two-step numerical framework coupling battery heat generation model with the multi-objective TO. We found that the lumped battery model could provide a reasonable estimation of the heat generation, especially at the C-rates between 1C and 3C, where the maximum deviation between numerical prediction and experiment was <2 %. In addition, the optimized cooling plate was affected greatly by the choices of heat loads and weighted objective functions. A higher heat load led to a more complex channel and narrower flow paths. In addition, by comparing with the benchmark model of the straight channels, the optimized model could reduce the pressure drop by 20–40 %. Furthermore, the hot spots in the system became more alleviated thanks to the optimized flow channels. The maximum temperature in the optimized model could be lower than that of the benchmark by up to 14 K at the charge rate of 3C. Additionally, by performing a cross-verification, the optimized plate under a high C-rate could reduce the maximum temperature to be lower than the allowable temperature of 323.15 K even when it was used under other charge rate conditions. Thus, the optimized plate under a high charge rate was found to be suitable for other C-rates as well. In summary, the present work established and validated the effective numerical framework which could be used to design a high-performance BTMS.