h a l f b a k e r yYeah, I wish it made more sense too.
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One of the big problem with white LEDs is that if they get too hot, the phosphor(s) loses efficiency, and your typical blue led with yellow phosphor shifts from warm (yellowish) to cool (bluish).
In a LED light bulb, where you've got several LEDs together, plus their electronics, plus a decorative
but heat retaining glass shell, designed to screw into a common Edison lamp socket, the problem is exacerbated.
Suppose there were a cylindrical piece of thermoelectric material just inside the bulb's screw base. With a bit of DC voltage applied to it, it could act as a heat pump, forcibly moving heat from the inside of the bulb (where the electronics and LEDs are), into the metal screw base.
Once the heat is forced into the screw base, it would be conducted into the lamp socket, and from there it could dissipate into the air.
This would allow LED lamps to be made with more and higher wattage LEDs, allowing them to replace higher wattage incandescent lamps.
The drawback of course is that the cooling system consumes energy, and makes the lamp more complicated.
On the other hand, some bright LED lamps have large heatsinks on the outside, detracting from the bulb's aesthetics, so there's something to say for *not* using passive cooling.
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I've seen 2 watt LED lamps which were designed to replace 40 watt incandescents. |
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As long as the active cooling system doesn't draw so many watts that it consumes as much energy as an incandescent, it's not a serious problem. |
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In Peltier Cooling the heat is only transported away, and would still have to be dissipated somewhere -> passive cooling fins. |
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"The drawback of course is that the cooling system consumes energy, and makes the lamp more complicated."
You're also dumping the heat where many table lamps have their power switch. |
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lamp sockets are insulated in most cases, lamps being the rare exception. |
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//In Peltier Cooling the heat is only transported away//
...to power the energy recovery Stirling engine, obviously. |
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If there were a magic heat disapation device in lamp bases it would be better to use a phase change liquid to get the heat there. As there isn't, as many are ceramic and design specifically to NOT conduct heat, this is an expensive drive down a dead end road. (-) |
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//30 watts of heat is added by I2R losses"//
So, invent higher voltage Peltiers. |
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