Experimental investigation in the pressure drop characteristics of supercritical carbon dioxide in the uniformly heated horizontal miniature tubes

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.