scholarly journals Numerical Analysis on the Radiation-Convection Coupled Heat Transfer in an Open-Cell Foam Filled Annulus

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2713 ◽  
Author(s):  
Xue Chen ◽  
Chuang Sun ◽  
Xinlin Xia ◽  
Rongqiang Liu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Pore Diameter ◽  
Radiation Heat Transfer ◽  
Radiation Heat ◽  
Open Cell ◽  
Coupled Heat Transfer ◽  
Open Cell Foam ◽  
Cell Foam

Forced flow and radiation-convection coupled heat transfer in an annulus filled with open-cell foam was numerically investigated at high temperatures. The Darcy-Brinkman-Forchheimer model was utilized to represent the fluid transport. The two-energy equation model was applied for the non-equilibrium heat exchange between the fluid and solid phases, while the radiation heat transfer within the foam material was solved using the P1 approximation. Two different cases of thermal boundary conditions were studied and discussed in detail, namely the inner wall with a constant heat flux while the outer wall was adiabatic (case I) and vice versa (case II). The effects of pertinent factors on the heat transfer characteristics were examined, such as the foam structural parameters and the radii ratio of the annulus. The temperature, local and average Nusselt number were predicted. The results indicate that neglecting the thermal radiation causes a large deviation in predicting the thermal performance of such foam-fluid systems. Increasing the porosity and pore diameter both promote the radiation heat transfer, while it is weakened by increasing the radii ratio. The average Nusselt number decreases as the porosity increases, while it exhibits a non-monotonic change with the pore diameter and radii ratio. Besides, case I shows a higher average Nusselt number than case II and presents an improved thermal performance.

Effect of Foam Properties on Heat Transfer in High Temperature Open-Cell Foam Inserts

2012 ◽  
Vol 95 (6) ◽  
pp. 2015-2021 ◽  
Author(s):  
Charles C. Tseng ◽  
Ruth L. Sikorski ◽  
Raymond Viskanta ◽  
Ming Y. Chen
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Open Cell ◽  
Open Cell Foam ◽  
Foam Properties ◽  
Cell Foam

INVESTIGATION OF HYDRODYNAMICS AND CONVECTIVE HEAT TRANSFER IN THE OPEN CELL FOAM MODELS OF VARIOUS GEOMETRY

2019 ◽  
Vol 57 (4) ◽  
pp. 109-121
Author(s):  
O.V. Soloveva ◽  
◽  
N.D. Yakimov ◽  
N.D. Chichirova ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Open Cell ◽  
Open Cell Foam ◽  
Cell Foam

scholarly journals Numerical Study of Entropy Generation due to Coupled Laminar and Turbulent Mixed Convection and Thermal Radiation in an Enclosure Filled with a Semitransparent Medium

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
M. Goodarzi ◽  
M. R. Safaei ◽  
Hakan F. Oztop ◽  
A. Karimipour ◽  
E. Sadeghinezhad ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Turbulent Flow ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Numerical Study ◽  
Radiation Heat Transfer ◽  
Radiation Heat ◽  
Semitransparent Medium

The effect of radiation on laminar and turbulent mixed convection heat transfer of a semitransparent medium in a square enclosure was studied numerically using the Finite Volume Method. A structured mesh and the SIMPLE algorithm were utilized to model the governing equations. Turbulence and radiation were modeled with the RNGk-εmodel and Discrete Ordinates (DO) model, respectively. For Richardson numbers ranging from 0.1 to 10, simulations were performed for Rayleigh numbers in laminar flow (104) and turbulent flow (108). The model predictions were validated against previous numerical studies and good agreement was observed. The simulated results indicate that for laminar and turbulent motion states, computing the radiation heat transfer significantly enhanced the Nusselt number (Nu) as well as the heat transfer coefficient. Higher Richardson numbers did not noticeably affect the average Nusselt number and corresponding heat transfer rate. Besides, as expected, the heat transfer rate for the turbulent flow regime surpassed that in the laminar regime. The simulations additionally demonstrated that for a constant Richardson number, computing the radiation heat transfer majorly affected the heat transfer structure in the enclosure; however, its impact on the fluid flow structure was negligible.

An Update on Heat Transfer in a Porous Insulation Medium in a Subsea Bundled Pipeline

2001 ◽  
Vol 123 (4) ◽  
pp. 285-290 ◽  
Author(s):  
Gary Zheng ◽  
Allen Verret ◽  
Nancy Burke ◽  
Neal Prescott ◽  
Dennis Cai ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pipe Wall ◽  
Effective Conductivity ◽  
Nitrogen Pressure ◽  
Heat Losses ◽  
Foam Material ◽  
Open Cell ◽  
Open Cell Foam ◽  
Energy Equations ◽  
Cell Foam

At the Multiphase ’99 Conference in Cannes, France, the authors presented a simple, yet general, formulation for effective conductivity of a porous insulation medium under pipeline application using fundamental continuity, momentum, and energy equations Zheng et al., 1999, “Heat Transfer in a Porous Insulation Medium in a Subsea Bundled Pipeline,” Paper No. 48 presented at Multiphase ’99, Cannes, France, ©BRH Group 1999. The effective conductivity was shown as a function of Darcy-modified Raleigh number only. The coefficients in the equation were then obtained from a set of tests for a simple pipe-in-pipe bundle with half-shell pieces of foam fitted around the inner pipe. Dramatic heat losses as experienced in some of field applications were recorded when the porous insulation foam is under high nitrogen pressure. All the heat losses were attributed to the increased heat convection within the porous insulation medium. Recognizing loose spaces between half-shells may contribute to the dramatic heat losses, the authors from R. J. Brown Deepwater conducted a new set of tests that used the same open-cell foam material, but with foamed-in-place application on the inner pipe wall. The new test data are used in this paper to derive an updated set of coefficients for the effective conductivity formulation. It is shown that such a foamed-in-place open-cell foam system maintains insulation effectiveness, even under high application pressures.

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