Thermo-hydraulic performance of heated vertical flows of supercritical CO2

Jiangfeng Guo; Jian Song; Yao Zhao; Konstantin S. Pervunin; Christos N. Markides

doi:10.1016/j.ijheatmasstransfer.2022.123437

Thermo-hydraulic performance of heated vertical flows of supercritical CO₂

Jiangfeng Guo^*, Jian Song, Yao Zhao, Konstantin S. Pervunin, Christos N. Markides

^*Corresponding author for this work

Chemical Engineering

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

The thermo-hydraulic characteristics of heated supercritical CO₂ (SCO₂) flows are investigated numerically in a vertical pipe from first- and second-law perspectives, and the influence of the flow direction, mass flux and heat flux (both distribution and average value) are evaluated. Two mass flux (254 kg/(m²∙s) and 400 kg/(m²∙s)) and three average heat flux (30 kW/m², 50 kW/m² and 70 kW/m²) conditions are simulated at an inlet temperature of 288 K and a pressure of 8.0 MPa (corresponding pseudo-critical temperature of 308 K) in a 4-mm diameter pipe. The simulation results reveal that the heat transfer is enhanced and the irreversibility is reduced in downward flows relative to flows without gravity, whereas the heat transfer deteriorates and the irreversibility is increased in upward flows. Both higher heat fluxes and lower mass fluxes also further hinder heat transfer in the upward flows, and multiple peaks are observed in the axial wall temperature profile. Moreover, it is found that the heat-flux distribution has a significant effect on the heat transfer performance of upward flows; the heat transfer further deteriorates and the irreversibility is further increased when a linearly decreasing heat-flux distribution is applied to the wall, while the heat transfer deterioration is alleviated when a linearly increasing heat-flux distribution is used. An analysis of the heat transfer mechanism indicates that the turbulence production in the core region of the supercritical flow is suppressed, and the accumulation of gas-like fluid in the near-wall region is promoted by the buoyancy effect in upward flows, leading to severe heat transfer deterioration and a sharp increase in the wall temperature, which is similar to the critical heat-flux phenomenon in subcritical boiling. The present study provides insights into the heat transfer characteristics of SCO₂ flows, as well as practical guidance on the design and optimisation of relevant components and equipment.

Original language	English
Article number	123437
Number of pages	17
Journal	International Journal of Heat and Mass Transfer
Volume	199
Early online date	18 Sept 2022
DOIs	https://doi.org/10.1016/j.ijheatmasstransfer.2022.123437
Publication status	Published - 15 Dec 2022

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). 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
Heat exchanger
Heat transfer
Numerical simulation
Supercritical CO

ASJC Scopus subject areas

Condensed Matter Physics
Mechanical Engineering
Fluid Flow and Transfer Processes

Access to Document

10.1016/j.ijheatmasstransfer.2022.123437Licence: None: All rights reserved

Cite this

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title = "Thermo-hydraulic performance of heated vertical flows of supercritical CO2",

abstract = "The thermo-hydraulic characteristics of heated supercritical CO2 (SCO2) flows are investigated numerically in a vertical pipe from first- and second-law perspectives, and the influence of the flow direction, mass flux and heat flux (both distribution and average value) are evaluated. Two mass flux (254 kg/(m2∙s) and 400 kg/(m2∙s)) and three average heat flux (30 kW/m2, 50 kW/m2 and 70 kW/m2) conditions are simulated at an inlet temperature of 288 K and a pressure of 8.0 MPa (corresponding pseudo-critical temperature of 308 K) in a 4-mm diameter pipe. The simulation results reveal that the heat transfer is enhanced and the irreversibility is reduced in downward flows relative to flows without gravity, whereas the heat transfer deteriorates and the irreversibility is increased in upward flows. Both higher heat fluxes and lower mass fluxes also further hinder heat transfer in the upward flows, and multiple peaks are observed in the axial wall temperature profile. Moreover, it is found that the heat-flux distribution has a significant effect on the heat transfer performance of upward flows; the heat transfer further deteriorates and the irreversibility is further increased when a linearly decreasing heat-flux distribution is applied to the wall, while the heat transfer deterioration is alleviated when a linearly increasing heat-flux distribution is used. An analysis of the heat transfer mechanism indicates that the turbulence production in the core region of the supercritical flow is suppressed, and the accumulation of gas-like fluid in the near-wall region is promoted by the buoyancy effect in upward flows, leading to severe heat transfer deterioration and a sharp increase in the wall temperature, which is similar to the critical heat-flux phenomenon in subcritical boiling. The present study provides insights into the heat transfer characteristics of SCO2 flows, as well as practical guidance on the design and optimisation of relevant components and equipment.",

keywords = "Buoyancy effect, Entropy generation, Heat exchanger, Heat transfer, Numerical simulation, Supercritical CO",

author = "Jiangfeng Guo and Jian Song and Yao Zhao and Pervunin, {Konstantin S.} and Markides, {Christos N.}",

note = "Funding Information: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska-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). 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: {\textcopyright} 2022 Elsevier Ltd",

year = "2022",

month = dec,

day = "15",

doi = "10.1016/j.ijheatmasstransfer.2022.123437",

language = "English",

volume = "199",

journal = "International Journal of Heat and Mass Transfer",

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AU - Guo, Jiangfeng

AU - Song, Jian

AU - Zhao, Yao

AU - Pervunin, Konstantin S.

AU - Markides, Christos N.

N1 - 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). 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

PY - 2022/12/15

Y1 - 2022/12/15

N2 - The thermo-hydraulic characteristics of heated supercritical CO2 (SCO2) flows are investigated numerically in a vertical pipe from first- and second-law perspectives, and the influence of the flow direction, mass flux and heat flux (both distribution and average value) are evaluated. Two mass flux (254 kg/(m2∙s) and 400 kg/(m2∙s)) and three average heat flux (30 kW/m2, 50 kW/m2 and 70 kW/m2) conditions are simulated at an inlet temperature of 288 K and a pressure of 8.0 MPa (corresponding pseudo-critical temperature of 308 K) in a 4-mm diameter pipe. The simulation results reveal that the heat transfer is enhanced and the irreversibility is reduced in downward flows relative to flows without gravity, whereas the heat transfer deteriorates and the irreversibility is increased in upward flows. Both higher heat fluxes and lower mass fluxes also further hinder heat transfer in the upward flows, and multiple peaks are observed in the axial wall temperature profile. Moreover, it is found that the heat-flux distribution has a significant effect on the heat transfer performance of upward flows; the heat transfer further deteriorates and the irreversibility is further increased when a linearly decreasing heat-flux distribution is applied to the wall, while the heat transfer deterioration is alleviated when a linearly increasing heat-flux distribution is used. An analysis of the heat transfer mechanism indicates that the turbulence production in the core region of the supercritical flow is suppressed, and the accumulation of gas-like fluid in the near-wall region is promoted by the buoyancy effect in upward flows, leading to severe heat transfer deterioration and a sharp increase in the wall temperature, which is similar to the critical heat-flux phenomenon in subcritical boiling. The present study provides insights into the heat transfer characteristics of SCO2 flows, as well as practical guidance on the design and optimisation of relevant components and equipment.

AB - The thermo-hydraulic characteristics of heated supercritical CO2 (SCO2) flows are investigated numerically in a vertical pipe from first- and second-law perspectives, and the influence of the flow direction, mass flux and heat flux (both distribution and average value) are evaluated. Two mass flux (254 kg/(m2∙s) and 400 kg/(m2∙s)) and three average heat flux (30 kW/m2, 50 kW/m2 and 70 kW/m2) conditions are simulated at an inlet temperature of 288 K and a pressure of 8.0 MPa (corresponding pseudo-critical temperature of 308 K) in a 4-mm diameter pipe. The simulation results reveal that the heat transfer is enhanced and the irreversibility is reduced in downward flows relative to flows without gravity, whereas the heat transfer deteriorates and the irreversibility is increased in upward flows. Both higher heat fluxes and lower mass fluxes also further hinder heat transfer in the upward flows, and multiple peaks are observed in the axial wall temperature profile. Moreover, it is found that the heat-flux distribution has a significant effect on the heat transfer performance of upward flows; the heat transfer further deteriorates and the irreversibility is further increased when a linearly decreasing heat-flux distribution is applied to the wall, while the heat transfer deterioration is alleviated when a linearly increasing heat-flux distribution is used. An analysis of the heat transfer mechanism indicates that the turbulence production in the core region of the supercritical flow is suppressed, and the accumulation of gas-like fluid in the near-wall region is promoted by the buoyancy effect in upward flows, leading to severe heat transfer deterioration and a sharp increase in the wall temperature, which is similar to the critical heat-flux phenomenon in subcritical boiling. The present study provides insights into the heat transfer characteristics of SCO2 flows, as well as practical guidance on the design and optimisation of relevant components and equipment.

KW - Buoyancy effect

KW - Entropy generation

KW - Heat exchanger

KW - Heat transfer

KW - Numerical simulation

KW - Supercritical CO

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