Specifics of Deteriorated Heat Transfer in SuperCritical Water (Liquid-Like State) Flowing Upward in a Short Bare Tube

Abstract

Water at SuperCritical Pressures (SCPs) is used in modern advanced coal-fired power plants around the world that are able to reach thermal efficiencies up to 55%, operating at 25-38 MPa pressures and 540-625°C turbine inlet temperatures. However, the current nuclear plants are not able to obtain such high thermal efficiencies (typically, 30-36%), due to the conventional Rankine cycles operating at conditions that are significantly below the supercritical ones, eventually, using only saturated primary steam within the pressure range of 4.7-7 MPa. The main focus of the paper is an investigation on specifics of Deteriorated Heat Transfer (DHT) in SuperCritical Water (SCW) (liquid-like state) flowing upward in a short bare tube, using data from I. Sikorsky Kiev Polytechnic Institute (KPI). Analysis of the experimental data showed an existence of three HT regimes: 1) Normal HT; 2) Improved HT; and 3) Deteriorated HT. Starting and developing of the deteriorated HT regime is also discussed. The experimental data along with preliminary calculations were provided by KPI while the analysis and report were carried out by the authors from UOIT.