Numerical study on the hydraulic and thermal performance of internally ribbed tubes in supercritical pressure and sub-critical two-phase flows

摘要

This paper numerically investigates the hydraulic and thermal performances of internally ribbed tubes under both sub-critical and supercritical water flows. A real case has been adopted to compare and validate the results with the experimental data. Heat transfer behavior and pressure drop characteristics have been analyzed under different fluid enthalpies. 15 and 25 MPa pressures are used to simulate the water flow inside the ribbed tube. Results indicate that computational method can provide a reliable framework which is capable of predicting the ribbed tubes performance. In sub-critical two-phase flow, vapor volume fraction increases continuously along the tube. It has been observed that the tube maintains the liquid near the wall region and delay the critical heat flux to the post dry-out condition. In supercritical flow, the spiral flow has been captured inside the tube. In addition, the heat transfer enhancement due to the pseudocritical thennophysical properties of the water is resolved.