Radiation Configuration Factors

Howell, J. R. A Catalog of Radiation Configuration Factors (McGraw-Hill, New York, 1982)... 

M. H. N. Naraghi, Radiation Configuration Factors between Disks and Axisymmetric Bodies, M.S. Thesis, Department of Mechanical Engineering, University of Akron, 1981. 

Fn = view factor or geometric configuration factor E = emissive power of emitting surface 2 = incident radiation-receiving surface... 

The emission coefficient was taken to be a constant value close to unity. The configuration factor, F, was calculated in a conventional way, treating the center of each strip as a point. Once the downward flame spread started the radiation from the wall flames and the pyrolysing lining material behind the flames was added to the smoke layer radiation. The heat flux to the walls was then calculated from the expression... 

F 12 is radiation view (configuration) factor between the target and the flame (0 < < 1)... 

Other names for the radiation shape factor are view factor, angle factor, and configuration factor. The energy leaving surface 1 and arriving at surface 2 is... 

Evaluate the configuration factors. The furnace can be sketched as in Fig. 7.3. Each of its six faces has a roman numeral and (for convenience later in the problem) the temperature of that face is shown. Since heat radiated from each face will impinge on every other face, there are 6(6 — 1) = 30 configuration factors to be determined. However, because of the reciprocity property and symmetry, fewer calculation steps will be needed. 

Related Calculations. If the six surfaces are not black but gray (in the radiation sense), it is nominally necessary to set up and solve six simultaneous equations in six unknowns. In practice, however, the network can be simplified by combining two or more surfaces (the two smaller end walls, for instance) into one node. Once this is done and the configuration factors are calculated, the next step is to construct a radiosity network (since each surface is assumed diffuse, all energy leaving it is equally distributed directionally and can therefore be taken as the radiosity of the surface rather than its emissive power). Then, using standard mathematical network-solution techniques, create and solve an equivalent network with direct connections between nodes representing the surfaces. For details, see Oppenheim [8],... 

To account for the effects of orientation on radiation heat transfer between two surfaces, we define a new parameter called the vieu factor, which is a purely geometric quantity and is independent of the surface properties and temperature. It is also called the shape factor, configuration factor, and angle factor. The view factor based on the assumption that the surfaces are diffuse emitters and diffuse reflectors is called the diffitse view factor, and the view factor based on the assumption that the surfaces are diffuse emitters but specular reflectors is called the specular view factor. In lliis book, we consider radiation exchange between diffuse surfaces only, and ihu.s the term view factor simply means diffuse view factor. 

D. C. Hamilton and W. R. Morgan. Radiation Interchange Configuration Factors. National Advisory Committee for Aeronautics, Technical Note 2836, 1952. 

The calculation of radiative exchange between two surfaces requires a quantity that describes the influence of their position and orientation. This is the view factor, which is also known by the terms configuration factor or angle factor. The view factor indicates to what extent one surface can be seen by another, or more exactly, what proportion of the radiation from surface 1 falls on surface 2. 

Czeslaw Buraczewski, Contribution to Radiation Theory Configuration Factors for Rotary Combustion Chambers, Pol. Akad. Nauk Pr. Inst. Masz Przeplyw, 74, pp. 47-73 (in Polish), 1977. 

A. Feingold and K. G. Gupta, New Analytical Approach to the Evaluation of Configuration Factors in Radiation from Spheres and Infinitely Long Cylinders, J. Heat Transfer, 92(1), pp. 69-76, February, 1970. 

Factors for finding radiation per unit area of the smaller surface, Sj. The arrangement (or configuration) factor, Fa, for all the above is 1.0. For other sh e factors, see reference 74. 

A very important aspect of radiative heat transfer is the system geometry. This is accounted for by using radiation shape factors, also called view factors, angle factors, or configuration factors and defined as follows... 

Radiative heat exchange between opaque solid surfaces through a nonparticipating fluid can be accounted for under the assumption of gray-diffusive surface radiation. Computation of the configuration factors (view factors) with account for the shadowing effect is described in detail in [41]. The total radiative flux incoming to the elementary surface element i(i = 1, N, where Ne is the total number of elementary surfaces on the boundary) is... 

Since radiation arriving at a black surface is completely absorbed, no problems arise from multiple reflections. Radiation is emitted from a diffuse surface in all directions and therefore only a proportion of the radiation leaving a surface arrives at any other given surface. This proportion depends on the relative geometry of the surfaces and this may be taken into account by the view factor, shape factor or configuration F, which is normally written as F, for radiation arriving at surface j from surface i. In this way, F,y, which is, of course, completely independent of the surface temperature, is the fraction of radiation leaving i which is directly intercepted by j. 

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