An experimental study has been conducted to investigate the heat transfer characteristics of supercritical carbon dioxide (sCO₂) uniformly heated in the horizontal circular smooth tube. The results illustrated that there was a significant difference in heat transfer between the top wall and bottom wall due to the buoyancy. Bulk flow acceleration cannot be negligible in the high heat flux region, which leads to heat transfer deterioration. A new heat transfer correlation is proposed, in which the buoyancy parameter and bulk flow acceleration have been taken into account. The new correlation and six classic correlations for sCO₂ are examined in horizontal tubes. The comparison indicates that the new correlation has a better performance for sCO₂ flowing through a horizontal heating tube under natural circulation conditions. For example, 94.9% of the calculated results using the new heat transfer correlation were within ±30% of the experimental results while only 87.9% of that using the Jackson correlation (the best of the six) were within the same error bands.

对超临界二氧化碳（sCO ₂）在水平圆形光滑管内均匀加热的传热特性进行了实验研究。结果表明，由于浮力，顶壁和底壁之间的传热存在显着差异。在高热通量区域，体流加速不可忽略，这会导致传热恶化。提出了一种新的传热关联式，其中考虑了浮力参数和体积流动加速度。在水平管中检查sCO ₂的新相关性和六个经典相关性。比较表明新的相关性对 sCO _{2有更好的性能}在自然循环条件下流过水平加热管。例如，94.9% 的使用新传热相关性的计算结果在实验结果的 ±30% 范围内，而使用杰克逊相关性（六个中最好的）的只有 87.9% 在相同的误差范围内。