A Novel Model of Turbulent Convective Heat Transfer in Round Tubes at Supercritical Pressures

Abstract

In the present study, a novel model was established to investigate the enhanced heat transfer to turbulent pipe flow of supercritical pressure fluids. The governing equations for the steady turbulent compressible pipe flow were simplified into the one-dimensional nondimensionalized forms based on the boundary layer theory. A conventional mixing length turbulence model for constant-property pipe flows was modified by introducing the effect of density fluctuations into the equations of turbulent transport, and the modified turbulence model was applicable to both constant-property and variable-property pipe flows. With the suggested model, which was a combination of the nondimensional governing equations and the modified turbulence model, the numerical calculations were carried out for the turbulent convective heat transfer of water in round tubes at supercritical pressures. The results showed that the present model can provide a relatively precise prediction about the effect of pressure, mass flux, and wall heat flux on heat transfer for supercritical fluid flows and greatly reduce the calculation workload. The modified turbulence model showed a much better agreement with the experimental results than the original turbulence model.

Acknowledgments

This work was financially supported by the National Natural Science Foundation of China for Creative Research Groups (grant 50821604).

Yu-Fei Mao is a Ph.D. student in the School of Energy and Power Engineering, Xi’an Jiaotong University. He is now working with the State Key Laboratory of Multiphase Flow in Power Engineering, and his current research interest is in the experimental and numerical study of heat transfer in straight and helical pipes at high and supercritical pressures.

Bo-Feng Bai is a professor in the School of Energy and Power Engineering, Xi’an Jiaotong University. He was granted the Ph.D. in thermal engineering from Xi’an Jiaotong University in 1999. He is now the deputy director of the State Key Laboratory of Multiphase Flow in Power Engineering. His main research interests include nonlinear boiling heat transfer and multiphase flow dynamics.

Lie-Jin Guo is a professor in the School of Energy and Power Engineering, Xi’an Jiaotong University. He was granted a Ph.D. in thermal engineering from Xi’an Jiaotong University in 1989. He is now the director of the State Key Laboratory of Multiphase Flow in Power Engineering and dean of the School of Energy and Power Engineering. His main research interests include hydrogen production by biomass gasification in supercritical water and from solar energy, high-pressure steam–water two-phase flow and boiling heat transfer, and multiphase flow in petroleum engineering.