Combined natural convection and radiation in a volumetrically heated fluid layer

Journal Article · Fri Feb 01 04:00:00 EST 1980 · J. Heat Transfer; (United States)

DOI:https://doi.org/10.1115/1.3244253· OSTI ID:5232396

Chawla, T C; Chan, S H; Cheung, F B; Cho, D H

The effect of radiation in combination with turbulent natural convection on the rates of heat transfer in volumetrically heated fluid layers characterized by high temperatures has been considered in this study. It is demonstrated that even at high Rayleigh numbers the radiation mode is as effective as the turbulent natural convection mode in removing the heat from the upper surface of the molten pools with adiabatic lower boundary. As a result of this improved heat transfer, it is shown that considerably thicker molten pools with internal heat generation can be supported without boiling inception. The total Nusselt number at a moderate but fixed value of conduction-radiation parameter, can be represented as a function of Rayleigh number in a simple power-law form. As a consequence of this relationship it is shown that maximum nonboiling pool thicknesses vary approximately inversely as the 0.9% power of internal heat generation rate. A comparison between exact analysis using the integral formulation of radiation flux and Rosseland approximation shows that the latter approximation bears out very adequately for optically thick pools with conduction-radiation parameters greater than or equal to 0.4 inspite of the fact that individual components of Nusselt number due to radiation and convection, respectively, are grossly in error. These errors in component heat fluxes are compensating due to the total heat balance constraint. However, the comparison between Rosseland approximation and exact formulation gets poorer as the value of conduction-radiation parameters decreases. This increase in error is principally incurred due to the error in estimating wall temperature differences.

• Research Organization: Argonne National Lab., IL
• OSTI ID: 5232396
• Journal Information: J. Heat Transfer; (United States), Journal Name: J. Heat Transfer; (United States) Vol. 102:1; ISSN JHTRA
• Country of Publication: United States
• Language: English

Related Subjects

640410* -- Fluid Physics-- General Fluid Dynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BOUNDARY CONDITIONS
CONVECTION
DATA
DIMENSIONS
ELECTROMAGNETIC RADIATION
ENERGY TRANSFER
FLUID FLOW
FLUIDS
FUELS
HEAT FLUX
HEAT TRANSFER
INFORMATION
LAYERS
LIQUID FUELS
NATURAL CONVECTION
NUMERICAL DATA
NUMERICAL SOLUTION
NUSSELT NUMBER
RADIATION FLUX
RADIATION TRANSPORT
RADIATIONS
ROSSELAND APPROXIMATION
THEORETICAL DATA
THERMAL RADIATION
THICKNESS
TURBULENT FLOW
VERY HIGH TEMPERATURE
WALLS