Abstracted from ASHRAE (1989), with permission
The effective emittance is E-1 = 1/e1 + 1/e2 - 1 where e1 and e2 are the airspace boundary surface emittancesPosition of airspace |
Direction of heat flow |
Airspace |
38 mm airspace |
89 mm airspace |
|||||||||
Effective emittance E | Effective emittance E | ||||||||||||
Mean temp., °C |
Temp. diff., °C |
0.03 |
0.05 |
0.2 |
0.5 |
0.82 |
0.03 |
0.05 |
0.2 |
0.5 |
0.82 |
||
Horizontal |
Up |
32 |
6 |
0.45 |
0.42 |
0.30 |
0.19 |
0.14 |
0.50 |
0.47 |
0.32 |
0.20 |
0.14 |
10 |
17 |
0.33 |
0.32 |
0.26 |
0.18 |
0.14 |
0.37 |
0.35 |
0.28 |
0.19 |
0.15 |
||
10 |
6 |
0.44 |
0.42 |
0.32 |
0.21 |
0.16 |
0.49 |
0.47 |
0.34 |
0.23 |
0.16 |
||
-18 |
11 |
0.35 |
0.34 |
0.29 |
0.22 |
0.17 |
0.40 |
0.38 |
0.32 |
0.23 |
0.18 |
||
-18 |
6 |
0.43 |
0.41 |
0.33 |
0.24 |
0.19 |
0.48 |
0.46 |
0.36 |
0.26 |
0.20 |
||
-46 |
11 |
0.34 |
0.34 |
0.30 |
0.24 |
0.20 |
0.39 |
0.38 |
0.33 |
0.26 |
0.21 |
||
-46 |
6 |
0.42 |
0.41 |
0.35 |
0.27 |
0.22 |
0.47 |
0.45 |
0.38 |
0.29 |
0.23 |
||
Down |
32 |
6 |
1.07 |
0.94 |
0.49 |
0.25 |
0.17 |
1.77 |
1.44 |
0.60 |
0.28 |
0.18 |
|
10 |
17 |
1.10 |
0.99 |
0.56 |
0.30 |
0.20 |
1.69 |
1.44 |
0.68 |
0.33 |
0.21 |
||
66 |
6 |
1.16 |
1.04 |
0.58 |
0.30 |
0.20 |
1.96 |
1.63 |
0.72 |
0.34 |
0.22 |
||
-18 |
11 |
1.24 |
1.13 |
0.69 |
0.39 |
0.26 |
1.92 |
1.68 |
0.86 |
0.43 |
0.29 |
||
-18 |
6 |
1.29 |
1.17 |
0.70 |
0.39 |
0.27 |
2.11 |
1.82 |
0.89 |
0.44 |
0.29 |
||
-46 |
11 |
1.36 |
1.27 |
0.84 |
0.50 |
0.35 |
2.05 |
1.85 |
1.06 |
0.57 |
0.38 |
||
-46 |
6 |
1.42 |
1.32 |
0.86 |
0.51 |
0.35 |
2.29 |
2.04 |
1.12 |
0.59 |
0.39 |
||
Position of airspace |
Direction of heat flow |
Airspace |
38 mm airspace |
89 mm airspace |
|||||||||
Effective emittance E | Effective emittance E | ||||||||||||
Mean temp., °C |
Temp. diff., °C |
0.03 |
0.05 |
0.2 |
0.5 |
0.82 |
0.03 |
0.05 |
0.2 |
0.5 |
0.82 |
||
45° slope |
Up |
32 |
6 |
0.51 |
0.48 |
0.33 |
0.20 |
0.14 |
0.56 |
0.52 |
0.35 |
0.21 |
0.14 |
10 |
17 |
0.38 |
0.36 |
0.28 |
0.20 |
0.15 |
0.40 |
0.38 |
0.29 |
0.20 |
0.15 |
||
10 |
6 |
0.51 |
0.48 |
0.35 |
0.23 |
0.17 |
0.55 |
0.52 |
0.37 |
0.24 |
0.17 |
||
-18 |
11 |
0.41 |
0.39 |
0.32 |
0.24 |
0.18 |
0.43 |
0.41 |
0.33 |
0.24 |
0.19 |
||
-18 |
6 |
0.49 |
0.47 |
0.37 |
0.26 |
0.20 |
0.52 |
0.51 |
0.39 |
0.27 |
0.20 |
||
-46 |
11 |
0.39 |
0.38 |
0.33 |
0.26 |
0.21 |
0.41 |
0.40 |
0.35 |
0.27 |
0.22 |
||
-46 |
6 |
0.48 |
0.46 |
0.39 |
0.30 |
0.24 |
0.51 |
0.49 |
0.41 |
0.31 |
0.24 |
||
Down |
32 |
6 |
0.89 |
0.80 |
0.45 |
0.24 |
0.16 |
0.85 |
0.76 |
0.44 |
0.24 |
0.16 |
|
10 |
17 |
0.63 |
0.59 |
0.41 |
0.25 |
0.18 |
0.62 |
0.58 |
0.40 |
0.25 |
0.18 |
||
10 |
6 |
0.90 |
0.82 |
0.50 |
0.28 |
0.19 |
0.83 |
0.77 |
0.48 |
0.28 |
0.19 |
||
-18 |
11 |
0.68 |
0.64 |
0.47 |
0.31 |
0.22 |
0.67 |
0.64 |
0.47 |
0.31 |
0.22 |
||
-18 |
6 |
0.87 |
0.81 |
0.56 |
0.34 |
0.24 |
0.81 |
0.76 |
0.53 |
0.33 |
0.24 |
||
-46 |
11 |
0.64 |
0.62 |
0.49 |
0.35 |
0.27 |
0.66 |
0.64 |
0.51 |
0.36 |
0.28 |
||
-46 |
6 |
0.82 |
0.79 |
0.60 |
0.40 |
0.30 |
0.79 |
0.76 |
0.58 |
0.40 |
0.30 |
||
Position of airspace |
Direction of heat flow |
Airspace |
38 mm airspace |
89 mm airspace |
|||||||||
Effective emittance E | Effective emittance E | ||||||||||||
Mean temp., °C |
Temp. diff., °C |
0.03 |
0.05 |
0.2 |
0.5 |
0.82 |
0.03 |
0.05 |
0.2 |
0.5 |
0.82 |
||
Vertical |
Horizontal |
32 |
6 |
0.70 |
0.64 |
0.40 |
0.22 |
0.15 |
0.65 |
0.60 |
0.38 |
0.22 |
0.15 |
10 |
17 |
0.45 |
0.43 |
0.32 |
0.22 |
0.16 |
0.47 |
0.45 |
0.33 |
0.22 |
0.16 |
||
10 |
6 |
0.67 |
0.63 |
0.42 |
0.26 |
0.18 |
0.64 |
0.60 |
0.41 |
0.25 |
0.18 |
||
-18 |
11 |
0.49 |
0.47 |
0.37 |
0.26 |
0.20 |
0.51 |
0.49 |
0.38 |
0.27 |
0.20 |
||
-18 |
6 |
0.62 |
0.59 |
0.44 |
0.29 |
0.22 |
0.61 |
0.59 |
0.44 |
0.29 |
0.22 |
||
-46 |
11 |
0.46 |
0.45 |
0.38 |
0.29 |
0.23 |
0.50 |
0.48 |
0.41 |
0.30 |
0.24 |
||
-46 |
6 |
0.58 |
0.57 |
0.46 |
0.34 |
0.26 |
0.60 |
0.58 |
0.47 |
0.34 |
0.26 |