I'm playing around with workplace illumination and have developed a 20 V –> 38 V PWM'able constant current source to drive my power LEDs (max power about 64W). So far, so good. However, I've nearly thermally killed one LED by fixing it on a significantly undersized heat sink ("luckily", the wire contacts unsoldered themselves just in time, stopping the process).
Now, I'm considering cooling options. Wanting to avoid active cooling (i.e. the humming of a fan), I was considering the "lazy" way out (dimension far from final, I don't have a heatsink candidate yet):
I'd like to mount the 19 x 19 mm LED directly onto an aluminum bar or profile. Now, I'm already playing around with thermal simulation software, but that seems over the top (and so far, it mostly crashes, plus I have a lot of theory to catch up on). So:
- Is there a well-known analytic model for heat distribution when attaching a constant-power heat source to a piece of metal?
- if not, is there a go-to simulation software? So far, I'm playing with Elmer.
- Is simulation the way to go here, at all, or is passive cooling damned for 60W LEDs?
Data (from LED datasheet):
- Junction-Case Thermal Resistance 0.8 K/W
- 19x19 mm
- max rated power 64.2 W
- continuous power I'm planning to use: 36.6 V · 0.72 A = 26.352 W