Computational Design Approach for Microchannel Cold Plate cooled with Supercritical Carbon Dioxide
Open Access
- Author:
- Ostasz, Mateusz
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 17, 2022
- Committee Members:
- Robert Kunz, Professor in Charge/Director of Graduate Studies
Alexander S Rattner, Thesis Advisor/Co-Advisor
Bladimir Ramos Alvarado, Committee Member - Keywords:
- Carbon Dioxide
Cold Plate
Optimization
Heat Transfer
Thermal Management - Abstract:
- Supercritical fluids have attracted increased attention over the past couple decades due to their unique heat transfer properties compared to conventional fluids at near-critical conditions. Such properties may be advantageous for high heat flux thermal management as this aspect becomes more demanding as technology progresses and requires sufficient cooling to sustain operation. This Thesis seeks to assess whether supercritical carbon dioxide (sCO_2) can outperform water for high flux thermal management via a mini/microchannel cold plate. To address this question, supercritical fluid channel flow heat transfer correlations were first assessed and downselected to permit performance comparison with conventional liquid coolants. Correlations were assessed using published Large Eddy Simulation (LES) and new Reynolds Averaged Navier Stokes (RANS) datasets. Next, parametric studies were conducted to identify microchannel geometries and operating regimes in which sCO_2 could outperform water in terms of pump work per cooled device area. Specifically, 2D conjugate heat transfer studies were performed to optimize channel geometry and minimize specific pump work given cooling requirements. Using the optimized channel geometry, a CFD-based topology and geometry optimization method was developed to optimize the flow distributer (header) design, seeking to balance flow distribution and pressure loss objectives. Based on the correlation assessment using established LES and RANS CFD datasets, Li et al [1] was evaluated to be the most appropriate correlation to model the heat transfer coefficient for the mini/microchannel cold plate. In the conjugate heat transfer studies, sCO_2 performed best with narrow channels with high aspect ratios at lower temperatures compared to water. It was superior to water at lower temperature limits of 70°C or lower for the entire range of pump work requirements. At higher temperatures, it is superior only at low pump works. For the header optimization, the headers contain elongated vanes that most optimally facilitate uniform flow and minimized pressure losses compared to conventional uniformly spaced vanes. Overall, there was significant improvement in the flow distribution from an open header to one with vanes; however, it resulted in a large increase in pressure drop. This was true for both 6 and 8 vane configurations.