Accurate knowledge and understanding of heat transfer characteristics near and above
critical conditions is crucial to the successful design of the SCWR. Many studies, both
numerical and experimental assessments have been conducted on bare tubes and simple
geometries like annuli. However, heat transfer performance studies of the fuel assemblies
for SCWR are scarce. Thus, there is still a lack of understanding of heat transfer
performance in the fuel assembly designs for SCWR. Moreover, the importance of this
study cannot be over-emphasized as it will broaden and better the understanding of the
concept of heat transfer in the rod bundle geometry by providing more numerical data.
In this study a 3D CFD code STAR CCM+ was used in assessing the performance of heat
transfer in the square fuel assembly of a High Performance Light Water Reactor (HPLWR).
Utilizing the computational environment and the flexibility of STAR CCM+ code, test
analysis was conducted using the four turbulence models, namely AKN low-Re, Standard
Lien’s low-Re, Standard Wilcox κ-ω and SST κ-ω to choose a suitable turbulence model
yielding satisfying prediction (capabilities) in describing the heat transfer and flow of
supercritical water in the fuel assembly “near”, at and after the pseudo-critical region. The
analysis was carried out at 25 MPa system operating pressure, mass flow rate of 0.167 kg/s
(601.2 kg/h), 300 °C inlet temperature with uniform heat flux of 650 kW/m2
sensitivity analysis was performed and SST κ-ω model was selected based on its simplicity
and superiority to others especially with regard to numerical stability. Moreover, SST κ-ω
model also does not involve damping functions, but allows simple Dirichlet specified
Furthermore, using the SST κ-ω with low y+ wall treatment the selected heat transfer
correlations were assessed. Overall, the Cheng et al. correlation provided the most
satisfying prediction for the wall temperatures in all the sub-channels and captured closely
Wataa’s Numerical data. This was followed by the McAdams correlation, but the
Dyadyakin and Popov and the Petukhov correlations also yielded acceptable results.
Test analysis results of the heat transfer correlation also confirmed the occurrence of heat
transfer enhancement and heat transfer deterioration at the pseudo-critical point and after
or beyond respectively. The maximum wall temperature was obtained in sub-channel 9,
the hottest sub-channel and exceeded the design limit of 620 °C by 60 °C for the Cheng
correlation while for the other correlations it was more. The difference in temperature
between the hottest and coldest sub-channels was approximately 80 °C.
Finally, parametric analysis was conducted in sub-channels 4 and 9 by varying mass flow
rates 0.1670 kg/s (601.2 kg/h) and 0.1559 kg/s (561.2 kg/h), pressure 23 MPa and 25 MPa
and with or without gravity. Results from this test analysis showed that mass flow rate,
pressure and gravity have significant influence. It was observed that at low mass flow rate
with varying pressure (23 MPa and 25 MPa), the temperatures significantly increased in
the heat transfer deterioration region. Nevertheless, experimental investigations involving
rod bundles adopted in this study should be conducted to validate the results obtained
numerically and address the inconsistence of the conclusions drawn, “when compared with
similar studies”. These experimental studies would also be helpful in validating similar
numerical studies in future.
Edu, F (2021). Heat Transfer Analysis of A Proposed Fuel Assembly For Supercritical Water Reactors Under Star CCM + CFD Code. Afribary.com: Retrieved April 10, 2021, from https://afribary.com/works/heat-transfer-analysis-of-a-proposed-fuel-assembly-for-supercritical-water-reactors-under-star-ccm-cfd-code
Frontiers, Edu. "Heat Transfer Analysis of A Proposed Fuel Assembly For Supercritical Water Reactors Under Star CCM + CFD Code" Afribary.com. Afribary.com, 06 Apr. 2021, https://afribary.com/works/heat-transfer-analysis-of-a-proposed-fuel-assembly-for-supercritical-water-reactors-under-star-ccm-cfd-code . Accessed 10 Apr. 2021.
Frontiers, Edu. "Heat Transfer Analysis of A Proposed Fuel Assembly For Supercritical Water Reactors Under Star CCM + CFD Code". Afribary.com, Afribary.com, 06 Apr. 2021. Web. 10 Apr. 2021. < https://afribary.com/works/heat-transfer-analysis-of-a-proposed-fuel-assembly-for-supercritical-water-reactors-under-star-ccm-cfd-code >.
Frontiers, Edu. "Heat Transfer Analysis of A Proposed Fuel Assembly For Supercritical Water Reactors Under Star CCM + CFD Code" Afribary.com (2021). Accessed April 10, 2021. https://afribary.com/works/heat-transfer-analysis-of-a-proposed-fuel-assembly-for-supercritical-water-reactors-under-star-ccm-cfd-code