4 Replies Latest reply on Apr 28, 2016 8:28 AM by Amit Katz

problem with simplified electronics thermal model

Richard Miner Apr 27, 2016 3:46 PM

Hi All,

New user here both with Solidworks Flow Simulation (2016) and this forum. I've modeled a simple resistor in flow simulation as follows:

1. materials for three components - conductor (Nichrome); conductor package material (Alumina); heatsink (aluminum)

2. Heat Source applied to the conductor (1 Watt)

3. Contact resistance between components - no resistance

3. Goal - Global Goal Max Temperature

4. Mesh - Global Mesh (moved level of initial mesh to 4); Local Mesh (Regional cuboid, refining cells at 3 for all three choices, all 3 advanced refinements are set at 2)

My issue deals with 'verification'. I want to see if Flow Simulation is at least 'ball park'. I've run the model several times using different mesh refinements, different materials, with and without contact resistances, etc. In all cases my max temperature is 73C +/- 3C on the heat sink. In the lab I applied exactly 1 watt to the resistor and waited for steady state. Then I used a very good (and well calibrated) thermal camera to measure the max temp of the heatsink...which was 53C. As you can see my results aren't even close.

Not sure where to go from here. Any suggestions would be welcome.

Thanks,

rich

resistor_04-27-16.zip 395.5 KB

Re: problem with simplified electronics thermal model

Amit Katz Apr 27, 2016 1:48 PM (in response to Richard Miner)

If you want to repeat your results from the lab, you need to set up your simulation likewise. I'm assuming the heatsink in your lab isn't floating in air, correct? Make sure you replicate your experimental conditions, including the temperature of the ambient air. Also when simulating natural convection you must make sure that your enable gravity in your calculations, it's in the "general settings" menu.
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- Re: problem with simplified electronics thermal model
  
  Richard Miner Apr 27, 2016 3:15 PM (in response to Amit Katz)
  
  Hi Amit,
  Thanks for the response. yes, the resistor is suspended in air and the ambient temp is 25C, also I did invoke gravity in the -y direction with the wizard upon set-up. I would be happy to 'pack and go' and send you the model for a quick review.
  
  Thanks!
  
  rich
  
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  - Re: problem with simplified electronics thermal model
    
    Richard Miner Apr 27, 2016 3:47 PM (in response to Richard Miner)
    
    Hi Amit,
    I edited my first post to include a zipped pack-and-go file.
    
    thanks,
    
    rich
    
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Re: problem with simplified electronics thermal model

Amit Katz Apr 28, 2016 8:28 AM (in response to Richard Miner)

I see, well that is odd behavior. How does the temperature of the hot cylinder compare with your lab data? Are the temperatures at the tips away from the heat sink comparable? Are they close to the 87C you see in the simulation? This is a fairly simple model so I'm not sure where the error could be coming from, other than maybe in the lab you weren't running at 1 W.
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