Heat Transfer Engineering

8.8. Radiation view factor and its determination

From the preceding discussion, it is clear that for the i^th surface in the enclosure, the net radiative flux depends on J_i and G_i. One can easily intuit that the orientations of the surface with respect to each other will play a critical part in the determination of G_i, J_i, and hence q_i. To be able to quantify this, we again take recourse to solid geometry and introduce a key quantity called the view factor or shape factor.

The view factor F_ij between two surface areas A_i and A_j is the fraction of radiation leaving the surface i that is intercepted by the surface j. From the foregoing discussion, the following points are evident.

1. 1. The view factor is dimensionless.
2. 2. The value of the view factor ...