Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube
Abstract
A number of computational works have been performed so far for the simulation of heat transfer in a supercritical fluid. The simulations, however, faced a lot of difficulties when heat transfer deteriorates due either to buoyancy or by acceleration. When the bulk temperature approaches the pseudocritical temperature the fluid experiences a severe axial density gradient on top of a severe radial one. Earlier numerical calculations showed, without exception, unrealistic overpredictions, as soon as the bulk temperature exceeded the pseudocritical temperature. The overpredictions might have been resulted from an inapplicability of widelyused turbulence models. One of the major causes for the difficulties may probably be an assumption of a constant turbulent Prandtl number. Recent research, both numerical and experimental, indicates that the turbulent Prandtl number is never a constant when the gradient of physical properties is significant. This paper describes the applicability of a variable turbulent Prandtl number to the numerical simulation of heat transfer in supercritical fluids flowing in narrow vertical tubes. (authors)
 Authors:
 Korea Atomic Energy Research Inst., 1045 Daedeokdaero, Daejeon (Korea, Republic of)
 Publication Date:
 Research Org.:
 American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
 OSTI Identifier:
 22105945
 Resource Type:
 Conference
 Resource Relation:
 Conference: ICAPP '12: 2012 International Congress on Advances in Nuclear Power Plants, Chicago, IL (United States), 2428 Jun 2012; Other Information: Country of input: France; 37 refs.; Related Information: In: Proceedings of the 2012 International Congress on Advances in Nuclear Power Plants  ICAPP '12 2799 p.
 Country of Publication:
 United States
 Language:
 English
 Subject:
 42 ENGINEERING; 22 GENERAL STUDIES OF NUCLEAR REACTORS; COMPUTERIZED SIMULATION; CRITICAL TEMPERATURE; DENSITY; FLUIDS; HEAT TRANSFER; PRANDTL NUMBER; TUBES; TURBULENT FLOW
Citation Formats
Bae, Y. Y., Hong, S. D., and Kim, Y. W.. Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube. United States: N. p., 2012.
Web.
Bae, Y. Y., Hong, S. D., & Kim, Y. W.. Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube. United States.
Bae, Y. Y., Hong, S. D., and Kim, Y. W.. 2012.
"Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube". United States.
doi:.
@article{osti_22105945,
title = {Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube},
author = {Bae, Y. Y. and Hong, S. D. and Kim, Y. W.},
abstractNote = {A number of computational works have been performed so far for the simulation of heat transfer in a supercritical fluid. The simulations, however, faced a lot of difficulties when heat transfer deteriorates due either to buoyancy or by acceleration. When the bulk temperature approaches the pseudocritical temperature the fluid experiences a severe axial density gradient on top of a severe radial one. Earlier numerical calculations showed, without exception, unrealistic overpredictions, as soon as the bulk temperature exceeded the pseudocritical temperature. The overpredictions might have been resulted from an inapplicability of widelyused turbulence models. One of the major causes for the difficulties may probably be an assumption of a constant turbulent Prandtl number. Recent research, both numerical and experimental, indicates that the turbulent Prandtl number is never a constant when the gradient of physical properties is significant. This paper describes the applicability of a variable turbulent Prandtl number to the numerical simulation of heat transfer in supercritical fluids flowing in narrow vertical tubes. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2012,
month = 7
}

The vertical upward flow of water in a heated tube at supercritical pressure is numerically simulated by a commercially available computational fluid dynamics code. The IAPWS95 formulation is used to obtain the water properties, which vary substantially at supercritical condition. To match the simulation with the experiment performed by Yamagata et al. (Int. J. Heat Mass Transfer, Vol. 15, 1972), the mass velocity is set to be 1260 kg/m{sup 2}xs and the wall heat fluxes 233, 465, 698, and 930 kW/m{sup 2}. To examine the reliability of the turbulence model at the supercritical flow, a series of simulations are performedmore »

Largeeddy simulation of turbulent flow with heat transfer in a heated vertical tube.
No abstract prepared. 
Convection heat transfer of CO{sub 2} at supercritical pressures in a vertical mini tube at relatively low reynolds numbers
Convection heat transfer of CO{sub 2} at supercritical pressures in a 0.27 mm diameter vertical mini tube was investigated experimentally and numerically for upward and downward flows at relatively low inlet Reynolds numbers (2900 and 1900). The effects of inlet temperature, pressure, mass flow rate, heat flux, flow direction, buoyancy and flow acceleration on the convection heat transfer were investigated. For inlet Reynolds numbers less than 2.9 x 10{sup 3}, the local wall temperature varies nonlinearly for both flow directions at high heat fluxes (113 kW/m{sup 2}). For the mini tube used in the current study, the buoyancy effect ismore » 
Experimental investigation of convection heat transfer of CO{sub 2} at supercritical pressures in a vertical circular tube
The convection heat transfer characteristics of supercritical CO{sub 2} in a vertical circular tube of 2 mm inner diameter were investigated experimentally for pressures ranging from 78 to 95 bar, inlet temperatures from 25 to 40 C, and inlet Reynolds numbers from 3800 to 20,000. The effects of the heat flux, thermophysical properties, buoyancy and thermal acceleration on the convection heat transfer were analyzed. The experimental results show that for high inlet Reynolds numbers (e.g. Re = 9000) and high heat fluxes, a significant local deterioration and recovery of the heat transfer was found for upward flows but not formore » 
Experimental investigation on heat transfer and frictional characteristics of vertical upward rifled tube in supercritical CFB boiler
Water wall design is a key issue for supercritical Circulating Fluidized Bed (CFB) boiler. On account of the good heat transfer performance, rifled tube is applied in the water wall design of a 600 MW supercritical CFB boiler in China. In order to investigate the heat transfer and frictional characteristics of the rifled tube with vertical upward flow, an indepth experiment was conducted in the range of pressure from 12 to 30 MPa, mass flux from 230 to 1200 kg/(m{sup 2} s), and inner wall heat flux from 130 to 720 kW/m{sup 2}. The wall temperature distribution and pressure dropmore »