The power density of an incandescent can be ten times that which is why they get too hot to touch whereas my LED lamps are barely above ambient.
Regarding LED SSFL, the concern on hand is the power density or the heat that must be removed at the device.
If you're looking at 80% efficiency 800W output magnetron, you have 1,000W going into the device. 800w that leaves as radiated energy.
What matters when it comes to heat issue is what didn't leave as radiated energy, the temperature it can withstand and which parts you can cover up.
So we only have 200W of heat to be dealt with at the back door despite it being a 1,000W device and a magnetron vacuum tube can handle a fair bit higher temperature than LED SSFL. This is what you think you understand but you don't.
The greater the temperature difference between an object and the ambient, the more thermal transfer by conduction and convection.
The same is true for radiant too but its not a fixed relationship with the same delta T.
100C surface surrounded by 50C surface can radiate 500W per sq per MetRE
150C into 100w surface for comparison sake can do 700w sq.m
150 into 50 can radiate 1200w sq.m. This being the case of HIDs that can operate the outer bulb to well beyond 150C and the ballast which can withstand 150C or higher. This is far beyond the temperature range power semiconductors can normally tolerate.
LEDs have to keep the hottest internal junction around 100C or less to get good life which probably limits fixture surface to 85C or so. The guts don't run hot enough to be able to get the lens running at 100C which limits heat rejection out the front. Heat comes from the LED ballast, LED thermal rejection, as well as conversion loss from phosphor blend in contact with the chip that is transferred back to the LED. So a 200W input power high bay LED excited solid state fluorescent luminaire that has to reject 120w through the heatsink in 55C ambient while keeping the heatsink at 85C or so explains why they have to be a whale. Letting it just run up to a higher temperature where it can easily radiate away 120W is not doable without frying the delicate LEDs.
So maybe, just maybe, you should give up trying to tell me what you think I don't understand.
ugh. All you've given us is . This what I do, therefore I understand and y'all are to believe it. Your discussion in this thread doesn't show you understand the realistic side. I believed others like kwired and Romex Jockey gets what you're just not getting.
LED SSFL is a seriously misunderstood technology with rather significant misinformation about them even in professional publications.
"Although SSL doesn't generate heat as a byproduct of generating light, the drivers and ballasts do. LEDs are sensitive to temperature fluctuation in the fixture."
http://www.facilitiesnet.com/lighti...Facilities-Management-Lighting-Feature--12236
Truth: LED solid state fluorescent lamp and regular FL ballasts are anywhere from 80-95% efficient. NEMA Premium ballasts are generally in the 90-95% range. Essentially all of the heat in solid state fluorescent lamp fixtures are generated from low quantum efficiency of the LED and conversion losses from the phosphor blend. Additional thermal management challenge exists for LEDs as they can't naturally disperse lamp element heat evenly through the entire lamp surface like other lighting technology.
"thermal management" is a way of saying engineering measures are needed to prevent LEDs from going south, because it is thermally delicate like computer chips unlike other lighting technologies.
