Experimental study of CHF in a vertical spirally internally ribbed tube under the condition of high pressures

Abstract

In the present paper, experiments of CHF were, respectively, conducted in a smooth tube and a four-head spirally internally ribbed tube. The smooth tube has an average inner diameter of 11.69 mm (∅18×3 mm). The four-head spirally internally ribbed tube has an average inner diameter of 11.26 mm (∅22×5.5 mm). The test section was vertically installed in the test loop and was uniformly heated by electricity. The working fluid was water, which entered into the test tube upward with an inlet subcooled temperature of 40–50 °C. The test pressure ranged from 10 to 21 MPa. The mass flux ranged from 400 to 1600 kg·m −2·s −1. The effects of various parameters such as mass flux and pressure on CHF are presented. The experimental results in the smooth tube and the four-head spirally internally ribbed tube are compared with each other. It shows that CHF can be enhanced by the four-head spirally internally ribbed tube in the test range. The experimental data in the smooth tube are used to evaluate a precise CHF correlation available in the literature. Good agreements are obtained.