Numerical investigation of the thermal-hydraulic performance of horizontal supercritical CO2 flows with half-wall heat-flux conditions

Jiangfeng Guo*, Jian Song*, Surya Narayan, Konstantin S. Pervunin, Christos N. Markides

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Thermo-hydraulic characteristics of supercritical CO2 (SCO2) flows in horizontal tubes with half-wall heat-flux conditions are investigated numerically, which is a common practice such as applications in solar parabolic trough collectors, while the heat transfer performance and the underlying mechanisms have not been fully understood. In heated flows, buoyancy acts to inhibit heat transfer when the top half of the tube wall is heated, however, when the bottom half of the tube wall is heated, this inhibition is alleviated, and the synergy between the temperature gradient and velocity fields improves thanks to the secondary flow in the near-wall region at the bottom wall. As a result, the heat transfer coefficient is ∼95% higher (on average) than in the case when the top half of the tube wall is heated. When the bottom half of the tube wall is cooled, buoyancy is expected to enhance heat transfer, while the synergy between the temperature gradient and velocity fields is supressed by the secondary flow in the near-wall region at the bottom of the tube. Conversely, when the top half of the tube wall is cooled, the buoyancy effect inhibits heat transfer, while the synergy between the temperature gradient and velocity fields is improved by the secondary flow in the near-wall region at the top of the tube, which eventually leads to an increase of ∼21% (on average) in the heat transfer coefficient relative to the case when the bottom half of the tube wall is cooled. Finally, the heat transfer discrepancy due to different heat flux conditions revealed in this study are employed in a heat exchanger model, indicating that the thermal performance of this device can be increased by ∼6% through an appropriate arrangement of the hot and cold flows without additional costs.

Original languageEnglish
Article number125845
Number of pages13
JournalEnergy
Volume264
Early online date28 Nov 2022
DOIs
Publication statusPublished - 1 Feb 2023

Bibliographical note

Funding Information:
This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. [ 882628 ]. The research was also supported by the Ministry of Science and Higher Education of the Russian Federation (‘Megagrant’ project no. 075-15-2019-1888 ), and the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-043 ). Data supporting this publication can be obtained on request from cep-lab@imperial.ac.uk . For the purpose of Open Access, the authors have applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission.

Publisher Copyright:
© 2022 Elsevier Ltd

Keywords

  • Buoyancy effect
  • Entropy generation
  • Field synergy principle
  • Heat exchanger
  • Heat transfer
  • Numerical simulation
  • Supercritical CO (SCO)

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Modelling and Simulation
  • Renewable Energy, Sustainability and the Environment
  • Building and Construction
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Pollution
  • Mechanical Engineering
  • General Energy
  • Management, Monitoring, Policy and Law
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

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