SUMMARY

This thesis presents a dual-loop single-phase thermosiphon-transformer assembly for power electronics cooling. The thermosiphon is incorporated into a grounded compact dynamic phase angle regulator (GCD-PAR) that will facilitate power routing and reduce line losses on the power grid. The power router utilizes power electronics that reject heat to a planar area, or cold plate, which must be cooled by an entirely passive system to comply with the minimum 30 year mean time between failures consistent with grid reliability requirements. This design will include a secondary-loop cooling path that utilizes the cooling oil already present in the transformer to also cool the power router. An analytical multi-physics thermosiphon model is developed that couples existing fluid dynamic and heat transfer correlations to create a description of the steady state operation of a specific dual-loop thermosiphon design. The model is validated experimentally and found to solve for steady state baseplate temperatures under maximum load within 2°C. The model is then used to validate the design for an assembly augmenting a three phase 1 MVA transformer with thermosiphon loops.