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D 13- Q4 (20 pts): Shown here is an enclosure that has 3 surfaces. Al and A3 are two coaxial parallel disks separated by a distance H=0.15 m; they sit at the top and bottom of a cylindrical furnace, respectively. De = 0.1m, D3 = 0.15m, and D2 = 0.3m. Use the equation in Table 13.2 to determine the view factor F13 and verify your result by comparing it with the value read from Fig. 13.5, calculate the other 8 view factors as well. A2 1 H A1 D:
71/2 2 In TABLE 13.2 View factors for three-dimensional geometries. Geometry Relation Aligned Parallel X = XL, Y = YIL Rectangles (Figure 13.4) [(1 + 2/(1+731 дXY 1 + x2 + 72 x + X(1 + 2)/2 tan (1 + Y3312 +7(1 + 2)2 tan Y (1 + 2)/2 Coaxial Parallel Disks R = r/L, R = r,/L (Figure 13.5) 1+R S = 1 + R F {S - [52 - 4(r/n)2112) х tan' - tany •>] = 515 - ? – Perpendicular Rectangles with a Common Edge (Figure 13.6) Z H = ZIX, W = Y/X 1 F W tan! 1 + H tan. лу W H 1 -(H + W21/2 tan! (H + W212 (1 + W2X1 + H) w?(1 + W2 + H) +-In 4 1 + 2 + H (I + W/(W2 + H) HP(1+H +W) (1 + H (H + W2) X + 1}}
1.0 8 8 6 6 0.8 5 4 0.6 3 IL = 2 1.5 0.4 1.25 1.0 0.8 0.2 0.6 0.4 0.3 0 0.1 0.2 2 4 0.4 0.6 0.8 1 Ur 6 8 10 FIGURE 13.5 View factor for coaxial parallel disks. .