Heat Transfer Characteristics of Porous Radiant Burners

1991 ◽  
Vol 113 (2) ◽  
pp. 423-428 ◽  
Author(s):  
T. W. Tong ◽  
S. B. Sathe
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Heat Generation ◽  
Numerical Study ◽  
Radiant Energy ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
High Heat Transfer ◽  
Energy Equations ◽  
Radiant Burners

This paper reports a numerical study of the heat transfer characteristics of porous radiant burners, which have significant advantages over conventional burners. The heat transfer characteristics are investigated using a one-dimensional conduction, convection, and radiation model. The combustion phenomenon is modeled as spatially dependent heat generation. Nonlocal thermal equilibrium between the gas and solid phases is accounted for by using separate energy equations for the two phases. The solid matrix is assumed to emit, absorb, and scatter radiant energy. The spherical harmonics approximation is used to solve the radiative transfer equation. The coupled energy equations and the radiative transfer equations are solved using a numerical iterative procedure. The effects of the various factors on the performance of porous radiant burners are determined. It is revealed that for a given rate of heat generation, large optical thicknesses and high heat transfer coefficients between the solid and gas phases are desirable for maximizing radiant output. Also, low solid thermal conductivities, scattering albedos and flow velocities, and high inlet environment reflectivities produced high radiant output.

Numerical Study of Heat Transfer Characteristics in Narrow Channel with Staggered Dimples

2014 ◽  
Vol 535 ◽  
pp. 71-74
Author(s):  
Hui Yong Chen ◽  
Shuai Guo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Numerical Study ◽  
Narrow Channel ◽  
High Heat ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
High Heat Transfer ◽  
Calculation Results

In this paper, numerical simulations were conducted to investigate the flow and heat transfer characteristics of dimple channels. To contrast with the channel with dimples, a numerical study on a smooth plate channel was also made. The results show that in dimple channel, flow separation occurred near dimple windward edge, low heat transfer rate was observed in these regions and dimple wake region owned high heat transfer rate. The calculation results show that the mean Nusselt numbers of dimple channel were 27.58 and the amplification is 15.2%. The friction factor of dimple channel is 0.018 and decrease by 5.26%, the thermal performance parameter TP is 1.18. It can be seen that the heat transfer in the channel is enhanced markedly with the staggered dimples.

Heat transfer characteristics of nanofluids from a sinusoidal corrugated cylinder placed in a square cavity

2021 ◽  
pp. 095440622110272
Author(s):  
Salaika Parvin ◽  
Nepal Chandra Roy ◽  
Litan Kumar Saha ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Average Nusselt Number ◽  
Numerical Study ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Transfer Characteristics ◽  
Wide Range

A numerical study is performed to investigate nanofluids' flow field and heat transfer characteristics between the domain bounded by a square and a wavy cylinder. The left and right walls of the cavity are at constant low temperature while its other adjacent walls are insulated. The convective phenomena take place due to the higher temperature of the inner corrugated surface. Super elliptic functions are used to transform the governing equations of the classical rectangular enclosure into a system of equations valid for concentric cylinders. The resulting equations are solved iteratively with the implicit finite difference method. Parametric results are presented in terms of streamlines, isotherms, local and average Nusselt numbers for a wide range of scaled parameters such as nanoparticles concentration, Rayleigh number, and aspect ratio. Several correlations have been deduced at the inner and outer surface of the cylinders for the average Nusselt number, which gives a good agreement when compared against the numerical results. The strength of the streamlines increases significantly due to an increase in the aspect ratio of the inner cylinder and the Rayleigh number. As the concentration of nanoparticles increases, the average Nusselt number at the internal and external cylinders becomes stronger. In addition, the average Nusselt number for the entire Rayleigh number range gets enhanced when plotted against the volume fraction of the nanofluid.

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