TY - JOUR
T1 - Numerical prediction of slug flow boiling heat transfer in the core-catcher cooling channel for severe accident mitigation in nuclear power plant
AU - Addad, Yacine
AU - Amidu, Muritala Alade
N1 - Funding Information:
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Muritala A. Amidu reports financial support was provided by Emirates Nuclear Energy Corporation. Muritala A. Amidu reports financial support was provided by Federal Authority for Nuclear Regulation.
Funding Information:
This research was fully funded by the Emirates Nuclear Technology Center (ENTC) co-sponsored by Khalifa University of Science and Technology (KU), the Emirates Nuclear Energy Company (ENEC), and the Federal Authority of Nuclear Regulation (FANR), United Arab Emirates.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/7
Y1 - 2022/7
N2 - This paper presents the steps followed to implement and validate a hybrid multiphase flow model in the open-source code, OpenFOAM. The modeling approach couples the interface capturing model with the dispersed flow model. The resulting multiphase model can be used to predict the slug flow boiling regime. The flow regime in question occurs during the external cooling of a core-catcher and in-vessel retention (IVR) which are severe accident mitigation strategies. A distinctive key feature of this multiphase-type flow is the co-existence of large-scale slug vapor bubbles with both dispersed vapor bubbles and the carrying liquid phase. The slug vapor bubbles are generated from the coalescence of the smaller dispersed bubbles. Also, due to the tilted orientation of the core-catcher and reactor vessel lower head (for the IVR option), these large-scale bubbles remain in the vicinity of the heated surface, while being transported by the flow. This is due to the buoyancy force acting upward in these two design configurations. The latter phenomenon engenders the fact that a liquid film is occupying a thin layer separating the large bubbles from the heated surface. Under such flow conditions, the existing wall boiling model, commonly known as the (Rensselaer Polytechnic Institute) RPI model, has been demonstrated to be inadequate for the determination of the boiling heat transfer characteristics. Therefore, an extended near-wall boiling model accounting for the conduction heat flux across the liquid film (trapped underneath the slug bubbles) is formulated and implemented in this study. Using this enhanced model, the simulation of a slug flow boiling on a downward-facing heated surface produces a better prediction of the wall superheat than the original model. In addition, the morphologies of the vapor slug coexisting with dispersed bubbles are adequately captured and compared fairly well with experimental visualizations. This new multiphase model is then used to simulate a prototypical core-catcher cooling channel. Once again, a fair representation of the wall heat transfer is predicted in good agreement with measurements. Finally, it has been also successfully proven that under subcooled nucleate flow boiling conditions, the present model can reproduce the RPI model predictions.
AB - This paper presents the steps followed to implement and validate a hybrid multiphase flow model in the open-source code, OpenFOAM. The modeling approach couples the interface capturing model with the dispersed flow model. The resulting multiphase model can be used to predict the slug flow boiling regime. The flow regime in question occurs during the external cooling of a core-catcher and in-vessel retention (IVR) which are severe accident mitigation strategies. A distinctive key feature of this multiphase-type flow is the co-existence of large-scale slug vapor bubbles with both dispersed vapor bubbles and the carrying liquid phase. The slug vapor bubbles are generated from the coalescence of the smaller dispersed bubbles. Also, due to the tilted orientation of the core-catcher and reactor vessel lower head (for the IVR option), these large-scale bubbles remain in the vicinity of the heated surface, while being transported by the flow. This is due to the buoyancy force acting upward in these two design configurations. The latter phenomenon engenders the fact that a liquid film is occupying a thin layer separating the large bubbles from the heated surface. Under such flow conditions, the existing wall boiling model, commonly known as the (Rensselaer Polytechnic Institute) RPI model, has been demonstrated to be inadequate for the determination of the boiling heat transfer characteristics. Therefore, an extended near-wall boiling model accounting for the conduction heat flux across the liquid film (trapped underneath the slug bubbles) is formulated and implemented in this study. Using this enhanced model, the simulation of a slug flow boiling on a downward-facing heated surface produces a better prediction of the wall superheat than the original model. In addition, the morphologies of the vapor slug coexisting with dispersed bubbles are adequately captured and compared fairly well with experimental visualizations. This new multiphase model is then used to simulate a prototypical core-catcher cooling channel. Once again, a fair representation of the wall heat transfer is predicted in good agreement with measurements. Finally, it has been also successfully proven that under subcooled nucleate flow boiling conditions, the present model can reproduce the RPI model predictions.
UR - http://www.scopus.com/inward/record.url?scp=85129765821&partnerID=8YFLogxK
U2 - 10.1016/j.nucengdes.2022.111796
DO - 10.1016/j.nucengdes.2022.111796
M3 - Article
AN - SCOPUS:85129765821
SN - 0029-5493
VL - 393
JO - Nuclear Engineering and Design
JF - Nuclear Engineering and Design
M1 - 111796
ER -