Transient heat transfer analysis

[juan.j.alfonzo]

Hello, 

I am trying to compare two heat sinks for an LED lighting fixture. For the first part I did a Steady State tranfer analysis getting results pretty close to a real physical test (max temp. 76 C). Now that I am setting up a Transient analysis the results are not what I was expecting, after letting it run for 4800 secs (max. temperature reaches just 34 C).

I used the same temperature coeficient curve that is used in AUTODESK MODULE 5 TRANSIENT HEAT TRANFER ANALYSIS.

The total LED power is 25 Watts. 

Thermal Conductivity factor and Specific heat for PCB were taken from specs sheets for Clad laminate Sheet. (Aluminum base).

TCF= 3.1955 J/smmC

SHC= 896 J/kgC

Could someone help me verifying if both analysis are correctly set up? 

Thanks a lot.

Juan Alfonzo