Numerical Analysis of Heat Transfer Test of Supercritical Water in a Tube Using the Three-Dimensional Two-Fluid Model Code

Abstract

The three-dimensional two-fluid model analysis code ACE-3D is developed in Japan Atomic Energy Agency for the thermal design procedure on two-phase flow thermal-hydraulics of light water-cooled reactors. In order to perform thermal hydraulic analysis of SCWR, ACE-3D is enhanced to supercritical pressure region. As a result, it is confirmed that transient change in subcritical and supercritical pressure region can be simulated smoothly using ACE-3D, that ACE-3D can predict the results of the past heat transfer experiment in the supercritical pressure condition, and that introduction of thermal conductivity effect of the wall restrains fluctuation of wall.

Supercritical-Pressure Light Water Cooled Reactors

“…Therefore, the applicable range of the conventional two-fluid model which is distinguished by the void fraction based on the liquid and gas phase must be improved (Misawa et al 2009a). Therefore, the applicable range of the conventional two-fluid model which is distinguished by the void fraction based on the liquid and gas phase must be improved (Misawa et al 2009a).…”

“…In Fig. 3.61 Region division of water in the JSME Steam Table (Misawa et al 2009a) The liquid and vapor properties in Eqs. In the critical region up to the critical pressure of 22.064 MPa, the void fraction represents from 0 to 1.…”

“…3.65. 3.64 Axial velocity, temperature and void fraction distributions (Misawa et al 2009a) This underestimation comes from the improper estimation of the turbulent heat flux near the wall, where the variance of thermal properties is large.…”

Assessment of Applicability of Two-Fluid Model Code ACE-3D to Heat Transfer Test of Supercritical Water Flowing in an Annular Channel

“…Therefore, the saturation curve defined only in the subcritical pressure region is extrapolated to the supercritical pressure region, so that the void fraction can be virtually defined even in the supercritical pressure region. 6) ACE-3D adopts a two-phase flow turbulent model based on a standard k-" model with a wall function. However, it was clarified by our previous study 6) that the standard k-" model underestimates the temperature of the heated wall because the utilization of the wall function causes the overestimation of the turbulent eddy diffusivity of the computational cell adjacent to the wall boundary.…”

“…6) ACE-3D adopts a two-phase flow turbulent model based on a standard k-" model with a wall function. However, it was clarified by our previous study 6) that the standard k-" model underestimates the temperature of the heated wall because the utilization of the wall function causes the overestimation of the turbulent eddy diffusivity of the computational cell adjacent to the wall boundary. This means that the wall treatment of the standard k-" model has a problem for the estimation of the turbulent heat flux on the wall boun- Assessment of Applicability of Two-Fluid Model Code ACE-3D to Heat Transfer Test of Supercritical Water Flowing dary.…”