RADIANT HEATING WITH INFRARED - Watlow

Percentage
Percentage
12
100
90
80
70
60
50
40
30
20
10
Figure 12 shows that polyethylene has absorption peaks in the 3.2 to 3.7 and
6.8 to 7.5 micron range. For maximum efficiency the peak energy wavelength
of the heater should be about 3.5 microns. Use Wien’s displacement law or
see Figure 4 to determine heater temperature:
Heater Temperature = 5269 microns - 460°
Peak Energy Wavelength
Heater Temperature = 5269 - 460
3.5
Heater Temperature = 1045°F
A heater operating at about 1045°F will have a peak energy wavelength of 3.5
microns. This matches the peak absorption range of polyethlene (Figure 12).
Radiant Rnergy Ratios For Several Blackbody Temperatures (Fig. 13)
Radiant Energy Ratios For Several Blackbody Temperatures (Fig. 13)
Percentage of radiant energy
that is at shorter wavelengths
than a specific value wavelength,
for heaters of a given blackbody
temperature
0
0.5 0.6 0.7 0.8 0.9 1.5 2 2.5 3 3.5 4 5 6 7 8 9 15 20
Source Temperatures (˚F) For The
Peak Radiation Band's Wavelength
(Wien's Displacement Law)
4760 ˚F
4000 ˚F
3000 ˚F
2000 ˚F
1800 ˚F
1600 ˚F
1400 ˚F
1200 ˚F
1000 ˚F
1.0 Wavelength (microns)
10
800 ˚F
600 ˚F
4760˚F 3017˚F 2150˚F 1275˚F 845˚F 410˚F 192˚F