Supercritical CO~2~ (sCO~­2~) can be utilized as a working fluid in various systems including high scale power cycle, portable power production unit, centralized coolant system and standalone cooling device. However, lack of accurate predication tools such as heat transfer coefficient correlations and insufficient knowledge about the mechanisms controlling heat transfer processes are hindering its practical realization in key energy and cooling systems. Available heat transfer correlations present large discrepancies and inconsistencies. Most of these correlations are empirical and are based on adaptation of constant properties correlations, such as the Dittus-Boelter or Gnilienski correlations.

 

The overall objective of the proposed study is to extend fundamental knowledge about heat transfer and fluid flow processes in conduits pertinent to sCO~2~ with an emphasis on length effects. The proposed effort seeks to change this state-of-affairs through an in-depth experimental study, supported by some modeling. The internal flow will have length scales from 2 mm to 20 mm, inlet Reynolds numbers from \~ 2×10^4^ to 25×10^4^ and heat fluxes from 0.1 kW/m^2^ 20 kW/m^2^. For such values of internal dimensions and test conditions effects of buoyancy on heat transfer can be influential. The designed test apparatus will be validated with high pressure air experiments. The results from all these measurements with supplemental data/correlations from the literature are then evaluated, consolidated, and broken down to separate heat transfer modes. They are reconstructed to develop transition criteria and mechanistic correlations that are independently validated


Study of Buoyancy Effects on Supercritical CO2 Heat Transfer in Circular Pipes

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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