With the growing demand of higher power density, at the expense of lesser environmental encroachment, use of supercritical carbon dioxide in miniature systems is becoming increasingly lucrative. However, concerned literature, particularly for horizontal geometry under heating condition, is relatively thin. Presently work, therefore, focuses on the numerical characterization of thermalhydraulics of supercritical carbon dioxide flowing through horizontal circular channel having diameter of 2 mm, with specific emphasis on the effect of local buoyancy. Three-dimensional turbulent simulations are performed over reasonably wide range of system pressure, heat flux and mass flux. Buoyancy-induced local recirculation, originating from density stratification, is found to have substantial influence on both azimuthal and axial profiles. Average heat transfer coefficient over the bottom half surface is noticeably higher than the same over top half surface because of thermal asymmetry, allowing delayed heat transfer deterioration there. Such disparity is amplified at higher heat fluxes, but reduces with increased pressure. The maxima in average heat transfer coefficient corresponds to the pseudocritical temperature. Larger mass flux augments heat transfer, with the peak moving downstream. Finally a buoyancy parameter is defined following literature on macrochannel, which is able characterize the loop performance satisfactorily.

随着对更高功率密度的日益增长的需求，以更少的环境侵害为代价，在微型系统中使用超临界二氧化碳变得越来越有利可图。但是，有关文献，特别是关于加热条件下的水平几何结构的文献相对较薄。因此，目前的工作集中在流经直径为2mm的水平圆形通道的超临界二氧化碳的热工流体的数值表征上，特别着重于局部浮力的影响。在相当大的系统压力，热通量和质量通量范围内进行了三维湍流模拟。发现由浮力分层引起的浮力引起的局部再循环对方位角和轴向剖面都具有实质性影响。由于热不对称，在下半表面上的平均传热系数明显高于在上半表面上的平均传热系数，从而使那里的延迟传热恶化。这种差异在较高的热通量下会放大，但会随着压力的增加而减小。平均传热系数的最大值对应于伪临界温度。较大的质量通量会增加热量传递，使峰向下游移动。最后，根据有关宏通道的文献定义了浮力参数，该参数能够令人满意地表征环路性能。但随着压力的增加而降低。平均传热系数的最大值对应于伪临界温度。较大的质量通量会增加热量传递，使峰向下游移动。最后，根据有关宏通道的文献定义了浮力参数，该参数能够令人满意地表征环路性能。但随着压力的增加而降低。平均传热系数的最大值对应于伪临界温度。较大的质量通量会增加热量传递，使峰向下游移动。最后，根据有关宏通道的文献定义了浮力参数，该参数能够令人满意地表征环路性能。