HEAT TRANSFER TO SUPERCRITICAL PRESSURE WATER IN A CIRCULAR AND SQUARE ANNULAR FLOW GEOMETRY

摘要

Heat transfer experiments were performed at similar conditions for both circle and square annular flow in the University of Wisconsin supercritical water (SCW) heat transfer facility. The circular annular test section geometry consists of a 1.07cm diameter heater rod within a 4.29cm diameter flow channel. The square annular test section geometry consists of the same 1.07cm diameter heater rod within a 2.88cm square cross section flow channel. This paper analyzes a subset of the experiments performed at a bulk temperature of 300°C, pressure of 25 MPa, relatively low mass velocities ranging from 350-700kg/m<'2>s, and heat flux values ranging from 125-650kW/m<'2>. These operating conditions produce wall temperatures ranging from 325 to 600°C, leading to normal and deteriorated heat transfer effects. Geometrical differences in heat transfer were seen when deterioration was present and increased as a function of heat flux. Under normal heat transfer conditions, Jackson's Nusselt correlation was found to capture experimental data within +20% to-10%. Watts Nusselt correlation showed a similar trend but under predicted measurements by 10%. In the deterioration region significant deviation from the correlation was found.