Heat Transfer Performance of Supercritical CO2 Under Variable Gravity

This study investigates the influence of gravitational force on the heat-transfer behavior of supercritical carbon dioxide (sCO₂) in compact heat-exchange systems. Understanding sCO₂ performance under changing gravitational force (g-force) is essential for thermal management technologies designed for extreme or rapidly varying environments, where compactness, high efficiency, and robust operation are required. Although sCO₂ is widely recognized for its advantageous thermophysical properties, the effect of dynamic g-forces on its heat-transfer characteristics remains insufficiently understood. To address this gap, an experimental campaign was developed using a rotating platform to generate controlled g-forces on flowing sCO₂. A secondary objective of this work is to evaluate the reliability of mass-flow measurement devices exposed to dynamic g-forces, as accurate mass-flow determination is critical for heat-transfer correlations and system design. Preliminary experiments comparing a Coriolis mass-flow meter with a Cox turbine volumetric flow meter show that the Coriolis device maintains accurate mass-flow readings even under dynamic g-forces, indicating its suitability for dynamic g-force applications. The findings from this work will support improved modeling of sCO₂ thermal behavior and provide a foundation for extending these insights to sCO₂-based zeotropic mixtures and designing next-generation heat-transfer systems intended for high-load, extreme-environment operation. Preliminary results have already suggest significant deviations from established heat transfer correlations for sCO₂ under normal gravity, and as the full experimental matrix is completed, the resulting data will further clarify how gravitational effects influence buoyancy driven convective heat transfer, flow stability, and system performance in supercritical CO₂ and sCO₂-based zeotropic-mixture thermal management systems.