Effect of emitted light on heat loss calculation.

[davidgcook]

I am doing a heat loss calculation for the avionics in the cabin of an aircraft. One of the LRUs is a backlight LCD. We are having a discussion on how to treat the light energy emitted from the display. One opinion is that the light energy should be subtracted from the system, the other is that the light energy will eventually be radiated back into the system as heat and therefore it should be left in. Has anyone on this forum worked on a similar problem, and how what the light handled.

 

[sathanasiou]

I believe you should include it in your calculations. I always take into account ligth energy- especially in areas with electronic equipment.

 

[MintJulep]

My gut feel is that the energy loss associated with light leaving the screen will be much smaller than the uncertainties in your calculation associated with radiated and convective heat transfer to the surroundings, so don't worry too much about it either way.

I mean, do you actually know what the convection coefficient will be in a "typical" installation? Ditto for emissivity of the stuff around your device?