科研之友
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摘要
Supercritical carbon dioxide (SCO2) has been extensively adopted in heat-transfer experiments due to its low critical point compared to supercritical water (SCW). While it helps to largely reduce the technical difficulty and cost, the experimental results need to be extrapolated to SCW using a set of reliable and well-validated fluid-to-fluid scaling criteria. In the present paper, a criterion for scaling the mass flux in normal and enhanced heat transfer regimes was achieved by using Computational Fluid Dynamic (CFD) approaches. This criterion as well as the available scaling laws were assessed based on a wide range of the experimental data. It was found that Prandtl number shows a significant and nonmonotone effect on the scaling of mass flux (and consequently Nusselt number). Similar exponents of the Prandtl number were obtained using different approaches, but a constant exponent failed to capture the nonmonotone effect, especially when the bulk temperature surpasses the pseudo-critical temperature where large variations in the thermophysical properties appear. A modified scaling criterion, which is applicable to the heat transfer deterioration occurred at low mass fluxes, was proposed for the Nusselt number. The deviation from the experimental data was significantly reduced after Grashof number was incorporated into the criterion.
- 出版日期2018-11
- 单位华北电力大学
