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Heat Power Transient analysis disagrees with hand calcs

Question asked by Wanfang Wu on Sep 12, 2016
Latest reply on Sep 13, 2016 by Wanfang Wu

Hey!

edit: Solved:

My error. simulation was correct. Bill McEachern is correct. I didn't set the material property under the SWX tree to 1060 aluminum so the mass evaluation tool used water to calculate mass which made my hand calc, Q=mcT, incorrect, disagreeing with the simulation.

 

 

I have 25 Watts total entering the interior faces of my 1060 Aluminum piece, initially 20C. My transient simulation with time increment of 0.05s showed temperatures of 23.7C after 1 sec. However, I calculated a 9C temperature change using Q= mCT. Q = 25J, m = 2.9g, C = 900J/kg*K. No convection or radiation effects were modeled. What did I do wrong?

Below are pictures of my settings. I have attached my the assembly file wherein I did my simulations.

Many thanks!

W

 

Settings:

23.7C after 1 sec with step size 0.1 (2 sec of simulation):

transientPowerResults.PNG

Heat Power Setting:

transientPowerSettingTurnedOff.PNG

Initial Temperature Setting:

00initialTemp.PNG

 

Confirmed 25W into system:

25WattIn.PNG

 

Mass properties:

edit: this shows incorrect mass b/c tool assumed material as water for calculating mass since i didn't define material under SWX tree

00heatingElement.PNG

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