- Access by Xinjiang University
Characteristics of turbulent heat transfer in an annulus at supercritical pressure
Phys. Rev. Fluids 2, 024602 – Published 2 February, 2017
DOI: https://doi.org/10.1103/PhysRevFluids.2.024602
Abstract
Heat transfer to fluids at supercritical pressure is different from heat transfer at lower pressures due to strong variations of the thermophysical properties with the temperature. We present and analyze results of direct numerical simulations of heat transfer to turbulent at 8 MPa in an annulus. Periodic streamwise conditions are imposed so that mean streamwise acceleration due to variations in the density does not occur. The inner wall of the annulus is kept at a temperature of 323 K, while the outer wall is kept at a temperature of 303 K. The pseudocritical temperature K, which is the temperature where the thermophysical properties vary the most, can be found close to the inner wall. This work is a continuation of an earlier study, in which turbulence attenuation due to the variable thermophysical properties of a fluid at supercritical pressure was studied. In the current work, the direct effects of variations in the specific heat capacity, thermal diffusivity, density, and the molecular Prandtl number on heat transfer are investigated using different techniques. Variations in the specific heat capacity cause significant differences between the mean nondimensionalized temperature and enthalpy profiles. Compared to the enthalpy fluctuations, temperature fluctuations are enhanced in regions with low specific heat capacity and diminished in regions with a large specific heat capacity. The thermal diffusivity causes local changes to the mean enthalpy gradient, which in turn affects molecular conduction of thermal energy. The turbulent heat flux is directly affected by the density, but it is also affected by the mean molecular Prandtl number and attenuated or enhanced turbulent motions. In general, enthalpy fluctuations are enhanced in regions with a large mean molecular Prandtl number, which enhances the turbulent heat flux. While analyzing the Nusselt numbers under different conditions it is found that heat transfer deterioration or enhancement can occur without streamwise acceleration or mixed convection conditions. Finally, through a combination of a relation between the Nusselt number and the radial heat fluxes, a quadrant analysis of the turbulent heat flux, and conditional averaging of the heat flux quadrants, it is shown that heat transfer from a heated surface depends on the density and the molecular Prandtl number of both hot fluid moving away from a heated surface as well as the thermophysical properties of relatively cold fluid moving towards it.
Physics Subject Headings (PhySH)
Article Text
References (21)
- M. Sharabi and W. Ambrosini, Discussion of heat transfer phenomena in fluids at supercritical pressure with the aid of CFD models, Ann. Nuclear Energy 36, 60 (2009).
- I. L. Pioro, H. F. Khartabil, and R. B. Duffey, Heat transfer to supercritical fluids flowing in channels: Empirical correlations (survey), Nucl. Eng. Des. 230, 69 (2004).
- W. B. Hall and J. D. Jackson, Laminarization of a turbulent pipe flow by buoyancy forces, in 11th ASME-AIChE National Heat Transfer Conference, Minneapolis, MN, ASME paper 69-HT-55, 1969.
- J. D. Jackson, Fluid flow and convective heat transfer to fluids at supercritical pressure, Nucl. Eng. Des. 264, 24 (2013).
- J. Y. Yoo, The turbulent flows of supercritical fluids with heat transfer, Annu. Rev. Fluid Mech. 45, 495, (2013).
- J. W. R. Peeters, R. Pecnik, M. Rohde, T. H. J. J. van der Hagen, and B. J. Boersma, Turbulence attenuation in simultaneously heated and cooled annular flows at supercritical pressure, J. Fluid Mech. 799, 505 (2016).
- O. Kunz, W. Wagner R. Klimeck, and M. Jaeschke, The GERG-2004 wide-range equation of state for natural gases and other mixtures, Technical report, GERG Technical Monograph 15, Fortschritt-Berichte VDI, VDI-Verlag, Düsseldorf (2007).
- A. Fenghour, W. A. Wakeham, and V. Vesovic, The viscosity of carbon dioxide, J. Phys. Chem. Ref. Data 27, 31 (1998).
- H. Kawamura, K. Ohsaka, H. Abe, and K. Yamamoto, DNS of turbulent heat transfer in channel flow with low to medium-high Prandtl number fluid, Intl. J. Heat Fluid Flow 19, 482 (1998).
- N. Kasagi and N. Shikazono, Contribution of direct numerical simulation to understanding and modeling turbulent transport, Proc. R. Soc. London A 451, 257 (1995).
- H. Kong, H. Choi, and J. S. Lee, Direct numerical simulation of turbulent thermal boundary layers, Phys. Fluids 12, 2555 (2000).
- S. Y. Chung and H. J. Sung, Direct numerical simulation of turbulent concentric annular pipe flow. Part II: Heat transfer, Int. J. Heat Fluid Flow 24, 399 (2003).
- M. Ould-Rouiss, L. Redjem-Saad, and G. Lauriat, Direct numerical simulation of turbulent heat transfer in annuli: Effect of heat flux ratio, Intl. J. Heat Fluid Flow 30, 579 (2009).
- L. Redjem-Saad, M. Ould-Rouiss, and G. Lauriat, Direct numerical simulation of turbulent heat transfer in pipe flows: Effect of Prandtl number, Intl. J. Heat Fluid Flow 28, 847 (2007).
- H. S. Dol, K. Hanjalic, and T. A. M. Versteegh, A DNS-based thermal second-moment closure for buoyancy convection at vertical walls, J. Fluid Mech. 391, 211 (1999).
- H. Abe, R. A. Antonia, and H. Kawamura, Correlation between small-scale velocity and scalar fluctuations in a turbulent flow, J. Fluid Mech. 627, 1 (2009).
- K. Fukugata, K. Iwamoto, and N. Kasagi, Novel turbulence control strategy for simultaneously achieving friction drag reduction and heat transfer augmentation, in Proceedings of the 4th International Symposium on Turbulence and Shear Flow Phenomena, Williamsburg, Virginia, June 27–29, 2005, pp. 307–312.
- J. M. Wallace, Quadrant analysis in turbulence research: History and evolution, Annu. Rev. Fluid Mech. 48, 131 (2016).
- W. W. Willmarth and S. S. Lu, Structure of the Reynolds stress near the wall, J. Fluid Mech. 55, 65 (1972).
- H. Kawamura, H. Abe, and Y. Matsuo, DNS of turbulent heat transfer in channel flow with respect to Reynolds and Prandtl number effects, Intl. J. Heat Fluid Flow 20, 196 (1999).
- B. Zappoli, D. Beysens, and Y. Garrabos, Heat Transfers and Related Effects in Supercritical Fluids (Springer, New York, 2015).