Simultaneous Estimation of Properties in a Combined Mode Conduction-Radiation Heat Transfer in a Porous Medium

2015 ◽  
Vol 45 (8) ◽  
pp. 699-713 ◽  
Author(s):  
Vijay K. Mishra ◽  
Subhash C. Mishra ◽  
Dipankar N. Basu
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Radiation Heat Transfer ◽  
Simultaneous Estimation ◽  
Radiation Heat ◽  
Combined Mode

scholarly journals Evaluation of radiation heat transfer in porous medial: Application for a pebble bed modular reactor cooled by CO2 gas

2013 ◽  
Vol 28 (2) ◽  
pp. 118-127
Author(s):  
Kamel Sidi-Ali ◽  
Khaled Oukil ◽  
Tinhinane Hassani ◽  
Yasmina Amri ◽  
Abdelmoumane Alem
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Free Convection ◽  
Radiation Heat Transfer ◽  
Convection Heat Transfer ◽  
Emergency Situation ◽  
System Of Equations ◽  
Radiation Heat ◽  
Pebble Bed ◽  
Free Convection Heat

This work analyses the contribution of radiation heat transfer in the cooling of a pebble bed modular reactor. The mathematical model, developed for a porous medium, is based on a set of equations applied to an annular geometry. Previous major works dealing with the subject have considered the forced convection mode and often did not take into account the radiation heat transfer. In this work, only free convection and radiation heat transfer are considered. This can occur during the removal of residual heat after shutdown or during an emergency situation. In order to derive the governing equations of radiation heat transfer, a steady-state in an isotropic and emissive porous medium (CO2) is considered. The obtained system of equations is written in a dimensionless form and then solved. In order to evaluate the effect of radiation heat transfer on the total heat removed, an analytical method for solving the system of equations is used. The results allow quantifying both radiation and free convection heat transfer. For the studied situation, they show that, in a pebble bed modular reactor, more than 70% of heat is removed by radiation heat transfer when CO2 is used as the coolant gas.

Natural Convection/Radiation Heat Transfer From Highly Populated Pin Fin Arrays

1985 ◽  
Vol 107 (1) ◽  
pp. 190-197 ◽  
Author(s):  
E. M. Sparrow ◽  
S. B. Vemuri
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Radiation Heat Transfer ◽  
Heat Transfer Characteristics ◽  
Radiation Heat ◽  
Pin Fin ◽  
Pin Fins ◽  
Pin Fin Arrays ◽  
Fin Length ◽  
Combined Mode

Experiments were performed to determine the combined-mode natural convection/radiation heat transfer characteristics of highly populated arrays of rodlike cylindrical fins (i.e., pin fins). The fins were oriented with their axes horizontal and were attached to a vertical heated baseplate. The investigated parameters included the number of fins in the array, the fin length and diameter, the baseplate-to-ambient temperature difference, and the presence or absence of adjacent shrouding surfaces. Finning was found to be highly enhancing (up to a sixfold increase in heat transfer), and even the longest fins were highly efficient. When the number of fins was increased for fixed values of the other parameters, the heat transfer increased at first, attained a maximum, and then decreased. Arrays having different diameter fins yielded about the same performance when the surface area of the fin-baseplate assembly was held fixed. Shrouding surfaces positioned close to the array decreased the rate of heat transfer. Calculations showed that the contribution of radiation was substantial and was greatest for more populous arrays, for longer fins, and at small temperature differences.

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