Journal
COMPUTERS & MATHEMATICS WITH APPLICATIONS
Volume 81, Issue -, Pages 562-572Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.camwa.2019.10.011
Keywords
Supercritical water; Roughness; Drag coefficient; Surface enlargement coefficient; Efficiency factor; Surface-average Nusselt number
Categories
Funding
- Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China [51888103]
- National Natural Science Foundation of China [51922086]
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The numerical simulation of supercritical water flow past a single rough sphere particle reveals that surface roughness affects the generation of separation bubbles but has little impact on the drag coefficient. Furthermore, the surface-average Nusselt number decreases with an increase in roughness.
Supercritical water fluidized bed is a novel gasification reactor which can achieve efficient and clean utilization of coal. The rough surface of particle produced during grinding and thermochemical conversion processing will deeply affect supercritical water-particle two-phase flow and heat transfer characteristics. In this paper, fully resolved numerical simulation of supercritical water flow past single rough sphere particle with the Reynolds number ranging from 10 to 200 was carried out to investigate the effect of surface roughness. The simulation results show that as roughness increases, the separation bubbles generated in the dimple enhance the flow separation but has no significant effect on the drag coefficient. Particle surface-average Nusselt number decreases with an increase of roughness and surface enlargement coefficient due to the isolation effect at low Re and local separation bubbles in the dimple at high Re. Furthermore, the effect of surface enlargement coefficient on heat transfer efficiency factor for supercritical water near the critical point is greater than that under constant property condition and has a higher dependence on Re. (C) 2019 Elsevier Ltd. All rights reserved.
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