Abstract Supercritical H2O/CO2 mixtures are the working fluids in a novel power generation system with coal gasified in supercritical water, but their heat transfer behaviors have received less attention compared with those of the supercritical water. Here, we experimentally investigated the heat transfer to these important mixtures. First, a stable and accurate apparatus was designed and established to measure the forced convection heat transfer coefficients (HTCs) of supercritical H2O/CO2 mixtures. The measurement uncertainty of this apparatus is lower than those reported in literature attributed to the well controls of the pressure and the component mass fraction throughout the apparatus. Then HTCs were measured for the H2O/CO2 mixtures that flow in a vertically upward smooth tube with the fluid pressure of 24 MPa, temperatures from 400 to 460 °C, CO2 mass fractions up to 20.1% and mass velocities up to 1270 kg m−2 s−1. Results show that the supercritical mixtures have similar convection heat transfer behavior to supercritical pure fluids, and that the forced convection heat transfer coefficients of these mixtures can be well predicted using the correlation developed for supercritical pure fluids. These results lay the foundation for designing heat transfer devices with supercritical mixtures as heat transfer fluids.

中文翻译：

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超临界区向 H2O/CO2 混合物传热的实验研究

摘要 超临界H2O/CO2混合物是煤在超临界水中气化的新型发电系统的工作流体，但与超临界水相比，其传热行为较少受到关注。在这里，我们通过实验研究了这些重要混合物的传热。首先，设计并建立了一种稳定且准确的装置来测量超临界 H2O/CO2 混合物的强制对流传热系数 (HTC)。该设备的测量不确定度低于文献中报告的那些，这归因于整个设备的压力和组分质量分数的井控制。然后测量在垂直向上的光滑管中流动的 H2O/CO2 混合物的 HTC，流体压力为 24 MPa，温度从 400 到 460 °C，CO2 质量分数高达 20.1%，质量速度高达 1270 kg m-2 s-1。结果表明，超临界混合物具有与超临界纯流体相似的对流传热行为，并且可以使用为超临界纯流体开发的相关性很好地预测这些混合物的强制对流传热系数。这些结果为设计以超临界混合物作为传热流体的传热装置奠定了基础。并且使用为超临界纯流体开发的相关性可以很好地预测这些混合物的强制对流传热系数。这些结果为设计以超临界混合物作为传热流体的传热装置奠定了基础。并且使用为超临界纯流体开发的相关性可以很好地预测这些混合物的强制对流传热系数。这些结果为设计以超临界混合物作为传热流体的传热装置奠定了基础。