Numerical Investigation of Heat Transfer to Supercritical Water in Vertical Tube under Semicircular Heating Condition

Abstract

In-depth understanding and analysis of turbulent convection heat transfer of supercritical water under semicircular heating conditions play a major role in system design and security. The inaccurate numerical results on simulating the buoyancy effect under deterioration heat transfer cases are partly attributed to the invalidity of the turbulent model. An improved turbulence model, which is validated suitable to three-dimensional model, is adopted in the present paper to numerical simulated flow and heat transfer in a vertical tube under semicircular heating condition. Heat transfer deterioration phenomenon occurs under semicircular heating condition, while the degree of deterioration is weakened due to the influence of variable physical properties and buoyancy effect. The velocity profile is distorted into “M-shape” in the heating side and present parabolic distribution in the adiabatic side, leading to different deterioration mechanisms under semicircular heating condition compared with uniform heating. The larger density difference between the heating side and the adiabatic side increases the shear stress production of turbulent kinetic energy; turbulent development is much faster recovery than the phenomenon in uniform heating condition. The results show that the semicircular heating condition can effectively alleviate the degree of heat transfer deterioration in a vertical tube.

Study on Convective Heat Transfer of Supercritical Nitrogen in a Vertical Tube for Liquid Air Energy Storage

“…where u i u j and u i T are the turbulent stress tensor and turbulent heat flux vector, respectively [11].…”

“…Over the past few decades, a considerable amount of efforts have been made to investigate the heat transfer behaviors of different supercritical fluids [10]. Wang et al [11] performed The detailed temperature distributions inside the test tube were numerically visualized and are displayed in Figure 8, for two cases with different values of heat flux at p = 3.8 MPa and G = 385 kg/m 2 •s. As indicated in the figure, in both cases, the N 2 temperature increased from less than pc to more than T pc , while the location of T pc moved from the tube wall and the tube centreline along a parabolic curve in the flow direction.…”

“…Over the past few decades, a considerable amount of efforts have been made to investigate the heat transfer behaviors of different supercritical fluids [10]. Wang et al [11] performed numerical simulations to explore heat transfer characteristics of supercritical water flowing upward in a circular tube with a semi-circular heating condition based on an improved turbulence model. They stated that heat transfer degradation might be mitigated via properly tuning the heating condition of the semi-circular profile.…”

Heat Transfer Limitations in Supercritical Water Gasification

“…Many research works, mainly performed numerically, have been published on this phenomenon, known as heat transfer deterioration (HTD) [41][42][43][44][45][46][47]. Recently, Wang et al [48] obtained, by simulation, that semicircular heating decreased the degree of HTD due to the greater turbulence produced by the greater density difference between the heating side and the adiabatic side.…”

Heat Transfer Analysis in Supercritical Hydrogen of Decoupled Poisoned Hydrogen Moderator with Non-Uniform Heat Source of Chinese Spallation Neutron Source

“…The heat transfer characteristics of supercritical fluid have been investigated extensively, especially the investigation of in tubes have become a focal point of research content [8][9][10][11]. Considering the influence of different factors on heat transfer, Wang et al [12] found that the buoyancy effect under the non-uniform heat source can effectively alleviate the degree of Heat Transfer Deterioration (HTD). Meanwhile, a modified turbulent model, which can accurately predict the influence of semicircular heating condition on the flow and heat transfer, was also proposed.…”