This study investigates experimentally the pressure drop characteristics of supercritical carbon dioxide uniformly heated in horizontal circular smooth tubes. The results illustrate that channel pressure drop would be enlarged with increases in mass flux and inlet fluid temperature, while it would decrease with increases in outlet pressure and tube diameter. Frictional pressure drop is the most dominant contributor (51%–85%) for total pressure drop, while accelerational pressure drop, up to 28%, and form loss, up to 24%, would contribute substantially with the increase of tube diameter due to significant reduction of fluid density at the channel outlet. Several classic correlations for turbulent flow and non-isothermal correlations for supercritical fluids are examined in smooth tubes. In overall, the existing empirical correlations could reasonably predict the frictional pressure drop within a relative error of about 30% against the present data set under uniform heating conditions.

本研究实验研究了在水平圆形光滑管中均匀加热的超临界二氧化碳的压降特性。结果表明，通道压降将随着质量通量和入口流体温度的增加而增大，而随着出口压力和管径的增加而减小。摩擦压降是总压降的最主要贡献者（51％–85％），而加速压降（高达28％）和形式损失（高达24％）将随着管径的增加而做出重大贡献。大大降低了通道出口处的流体密度。在光滑管中检查了几种典型的湍流相关性和超临界流体的非等温相关性。总体而言，