Experimental investigation on pressure drop of supercritical water in an annular channel

This paper presents an experimental investigation of the pressure drop and friction factor of supercritical water in an annular channel. The gap and the full length of the annulus are 4 mm and 1400 mm, respectively. The experimental pressure ranges from 23 to 28 MPa, mass flux ranges from 700 to 1500 kg/(m(2)s), and heat flux on the inner wall ranges from 200 to 1000 kW/m(2). Results showed that the frictional pressure-drop increases significantly with increasing mass flux, particularly when the bulk enthalpy surpasses the pseudo-critical enthalpy. A local hump in the friction factor was observed corresponding to the pseudo-critical enthalpy, which becomes stronger with the decrease of mass flux or pressure. The assessment of correlations demonstrated that constant-property-based correlations fail to predict the friction factor of supercritical water. Hence, an improved correlation was proposed which captures 82.6% of the experimental data within 25% error band.