The Temperature Distribution of a Sphere Placed in a Directed Uniform Heat Flux

1981 ◽  
Vol 103 (2) ◽  
pp. 399-401 ◽  
Author(s):  
K. A. Werley ◽  
J. G. Gilligan
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Uniform Heat Flux ◽  
Uniform Heat

The Temperature Distribution Within a Sphere Placed in a Directed Uniform Heat Flux and Allowed to Radiatively Cool

1985 ◽  
Vol 107 (1) ◽  
pp. 28-32 ◽  
Author(s):  
D. Duffy
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Analytic Solution ◽  
Blackbody Radiation ◽  
Heat Fluxes ◽  
Uniform Heat Flux ◽  
Transform Methods ◽  
Uniform Heat ◽  
Large Heat

The temperature field within a sphere is found when the sphere is heated by a directed heat flux and cooled by blackbody radiation. For small heat fluxes, the analytic solution is obtained by transform methods. For large heat fluxes, the solution is computed numerically.

Numerical Investigation of Supercritical Water Flow in a 2x2 Rod Bundle Under Non-Uniform Heat Flux

2016 ◽  
Author(s):  
Marcin Rowinski ◽  
Yeng Ch. Soh ◽  
Timothy J. White ◽  
Ching Ch. Chieng ◽  
Jiyun Zhao
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Supercritical Water ◽  
Wall Temperature ◽  
Working Fluid ◽  
Uniform Heat Flux ◽  
Fuel Channel ◽  
Fuel Rod ◽  
Uniform Heat

Generation III/III+ nuclear reactors operate with working fluid under subcritical conditions (Tc = 647K, pc = 22.115MPa). The efficiency, limited by the ratio of source and sink temperatures, is restricted by operating below the critical temperature. The supercritical water reactors (SCWRs) are able to rise efficiency limit while operating at the supercritical conditions. The amount of energy carried by working fluid is higher leading to potential efficiency improvement of nearly 30% above current nuclear stations. Therefore, rendering nuclear energy as one of the most efficient decarbonized electrical energy sources with efficiency of 45% and capacity factor of ca. 90%. Typical capacity factors of competing wind turbines and solar PV cells reaches 45% and 15% while the efficiencies 50% and 45%, respectively. In a subcritical reactor a uniform heat flux is generated due to relatively constant fuel moderation. However, due to a change of density during transition from sub- to supercritical conditions, the fuel moderation is uneven along the fuel rod and results in a non-uniform heat generation. The literature on SCWR neutronics suggests higher heat generation at the fuel channel entrance. In this paper we simulated for the first time such non-uniform heat flux generated in a SCWR, we analyze the impacts of such flux on the working medium flow and suggest ways to mitigate negative impacts of non-uniform heat flux. The study was conducted with use of Computational Fluid Dynamics (CFD) software. Obtained results show that the shape of heat flux curve along the channel highly influences the wall temperature distribution along the fuel channel. The differences in maximum wall temperatures can be up to 200K for different curve’s shape. Moreover, the maximum wall temperature is always higher than in default case i.e. when uniform heat flux is applied. It is possible to control the wall temperature distribution by adjusting the shape of heat flux along the axis. Such adjustment can be made by using different enrichment levels along the fuel rod axis, unfortunately any change in power distribution caused rapid temperature increase at the upstream location.

A Nondimensional Analysis of Boiling Dry a Vertical Channel with a Uniform Heat Flux

1981 ◽  
Vol 103 (4) ◽  
pp. 667-672 ◽  
Author(s):  
K. H. Sun ◽  
R. B. Duffey ◽  
C. Lin
Keyword(s):  
Heat Flux ◽  
Nuclear Power ◽  
Closed Form Solution ◽  
Vertical Channel ◽  
Form Solution ◽  
Uniform Heat Flux ◽  
Two Phase ◽  
Drift Flux ◽  
Rod Bundle ◽  
Uniform Heat

A thermal-hydraulic model has been developed for describing the phenomenon of hydrodynamically-controlled dryout, or the boil-off phenomenon, in a vertical channel with a spatially-averaged or uniform heat flux. The use of the drift flux correlation for the void fraction profile, along with mass and energy balances for the system, leads to a dimensionless closed-form solution for the predictions of two-phase mixture levels and collapsed liquid levels. The physical significance of the governing dimensionless parameters are discussed. Comparisons with data from single-tube experiments, a 3 × 3 rod bundle experiment, and the Three Mile Island nuclear power plant show good agreement.

scholarly journals Class of dilute granular Couette flows with uniform heat flux

2011 ◽  
Vol 83 (2) ◽  
Author(s):  
Francisco Vega Reyes ◽  
Vicente Garzó ◽  
Andrés Santos
Keyword(s):  
Heat Flux ◽  
Uniform Heat Flux ◽  
Uniform Heat
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