Influence of fluid-property variation on turbulent convective heat transfer in vertical annular channel flows.
Conference
·
OSTI ID:911126
Influence of strongly-varying properties of supercritical-pressure fluids on turbulent convective heat transfer is investigated using direct numerical simulation. We consider thermally-developing upward flows in a vertical annular channel where the inner wall is heated with a constant heat flux and the outer wall is insulated. CO2 is chosen as the working fluid at a pressure to 8 Mpa, and the inlet Reynolds number based on the channel hydraulic diameter and the bulk velocity is Re0 = 8900. It is shown that turbulent convective heat transfer characteristics of supercritical flow are significantly different from those of constant-property flow mainly due to spatial and temporal variations of fluid density. Non-uniform density distribution causes fluid particles to be accelerated either by expansion or buoyancy force near the heated wall, while temporal density fluctuations change the transport characteristics of turbulent heat and momentum via the buoyancy production terms arising from the correlations such as p1u1x, p1u1r and p1h1. Among various turbulence statistics, the streamwise turbulent heat flux shows a very peculiar transitional behavior due to the buoyancy effect, changing both in sign and magnitude. Consequently, a non-monotonic temperature distribution is developed in the flow direction, causing severe impairment of heat transfer in supercritical flows.
- Research Organization:
- Idaho National Laboratory (INL)
- Sponsoring Organization:
- DOE - NE
- DOE Contract Number:
- AC07-99ID13727;
- OSTI ID:
- 911126
- Report Number(s):
- INL/CON-05-00568
- Conference Information:
- NuReTH-11,Avignon, France,10/02/2005,10/06/2005
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
buoyancy effect
direct numerical simulation
DISTRIBUTION
FLUCTUATIONS
HEAT FLUX
HEAT TRANSFER
HYDRAULICS
PRODUCTION
REYNOLDS NUMBER
SIMULATION
STATISTICS
supercritical fluid
TEMPERATURE DISTRIBUTION
TRANSPORT
TURBULENCE
TURBULENT FLOW
VELOCITY
WORKING FLUIDS
buoyancy effect
direct numerical simulation
DISTRIBUTION
FLUCTUATIONS
HEAT FLUX
HEAT TRANSFER
HYDRAULICS
PRODUCTION
REYNOLDS NUMBER
SIMULATION
STATISTICS
supercritical fluid
TEMPERATURE DISTRIBUTION
TRANSPORT
TURBULENCE
TURBULENT FLOW
VELOCITY
WORKING FLUIDS