Defog/defrost heater on window 1

[dsjon10]

I am working on an upgrade to an optical system that requires adding a defogger/defroster. I have been researching adhering a flexible silicone rubber heater to the surface of the window. Does anyone know the min temperature setting that will be required to reduce fog and frost? I am basing this off a rear window defroster on a car. Does anyone know how hot those systems usually get before shutdown?

 

[Latexman]

The temperature must be raised above the "dew point".

Good luck,
Latexman

 

[IRstuff]

It depends on the operating conditions, obviously. A defog/deice for 400 mph -40°C is quite different than one for 10mph -10°C. Note also, silicone rubber is not exactly optical quality material, and the net effect might be no improvement over just plain fogging. The traditional reference for this type of work as far as the thermodynamics is SAE AIR 1168/4 Ice, Rain, Fog, and Frost Protection, specifically Table 3F-3 Heat Requirements at Various Cruise Speeds

TTFN

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