Study of Heat Transfer in Circular Tubes with Supercritical Fluid by the STAR-CCM+ CFD Code

ABSTRACT

Supercritical Cooled-Water Reactor (SCWR) which is planned to be deployed by 2030

derives its concept from Light Water Reactors (Boiling Water Reactor (BWR), Pressurized

Water Reactor (PWR) and Fossil Fired Coal Plant but with a simpler design. Due to the

strong variations of density at supercritical pressure, the SCWR is likely to inherit some of

the issues related to the LWR’s in terms of heat transfer (e.g. thermal crisis). This research

was undertaken in order to better understand the phenomena of heat transfer as applied to

SCWR and also to test the applicability of Reynolds-Average Navier-Stokes (STARCCM+

CFD code). Kim’s et al., (2005) data which employs supercritical CO2 as a simulant

of water at 8 MPa was used to test the applicability. The computational simulation by

STAR-CCM+ on the prediction of a 2-D axisymmetric heat transfer of carbon dioxide at

supercritical pressure flowing upward through heated cross-section of a circular tube was

performed with six (6) low-Reynolds number models;  -epsilon AKN, EB, standard low-

Re and V2F with two  -ω turbulence models; SST and standard Wilcox with low y+ wall

treatment. The results of heat fluxes of 20, 23, 30 and 40 kW/m2 and mass flux of 314

kg/m2s were compared to the experimental data of Kim et al., (2005). The Standard low-

Reynolds turbulence models were seen to have better capabilities to predict the heat

transfer behaviour of supercritical CO2 as observed in the experiment. The  -ω models

did not perform favourably in the prediction of heat transfer deterioration. The V2F

turbulence model performed better than the other models quantitatively when compared to

the experimental data. The results of the simulation has been found to be able to reproduce

the general features exhibited in the experimental data even though they over predicted the

observed heat transfer deterioration both quantitatively and qualitatively.