heat transfer in mechanica

[tonz1984]

Hi,

I am running a thermal analysis on an LED fitting that consists of several LEDs attached to a finned aluminium heat sink.

I've applied a heat load to the surface of the LED which represents the power/heat output from the LED. Once the analysis is run the Max Temperature shows what temperature the LED is operating at and how effective the heatsink is at conducting heat.

Consistently results from the analysis of the LED temp are correct (i.e. the temperature is the same as the actual measured temperature from an experiment) but the temperature of the rest of the heatsink is around 15-20 degree's cooler than measured in the experiment.

Would anyone have an idea of why one part of the simulation is correct but not the other? If the temperature of the heatsink was higher, then surely the temperature of the LED would also be higher.

e.g.

LED TEMP (simulation) - 95degrees
LED TEMP (experiment) - 95degrees

HEATSINK TEMP (simulation) - 43degrees
HEATSINK TEMP (experiment) - 65degrees

 

[Nettuno]

Hi tonz1984,

How about the boundary conditions?
If I understand good your heat sink should exchange heat with the boundary (open air or cooling system), and the Thermal Analysis ends when it gets a heat balance.
As far as I know in order to perform a Thermal Analysis you have to provide a load set (heat load) and a constraint set (Prescribe Temperature, Convection Condition), what constraint did you apply to your model?
Understanding how the model has been set would help to understand why the simulation results are different from the experimental data.

BR
Nettuno