# Temperature and heat flux wall boundary condition

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 February 1, 2014, 03:32 Temperature and heat flux wall boundary condition #1 Member   Hamid Join Date: Dec 2010 Location: Iran Posts: 30 Rep Power: 15 Dear All, In my model, I have a coil which transfers the heat flux 5000 w/m2 to gasoline. I set the wall of coil boundary condition by this heat flux. After convergence the model, I checked the surface temperature of the coil. It was 1000 K. But In real, the surface temperature of the coils shouldn't exceed 400 K. How can I control the temperature and heat flux of the coil? Any help would be appreciated Hamid

 February 1, 2014, 13:00 #2 Senior Member   Hamid Zoka Join Date: Nov 2009 Posts: 282 Rep Power: 18 where does the 5000 w/m2 come from? It seems that heat flux is highly over predicted. could you give an image of your computation domain plus boundaries defined?

February 2, 2014, 00:05
#3
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Hamid
Join Date: Dec 2010
Location: Iran
Posts: 30
Rep Power: 15
Quote:
 Originally Posted by Hamidzoka where does the 5000 w/m2 come from? It seems that heat flux is highly over predicted. could you give an image of your computation domain plus boundaries defined?

Dear Hamidzoka,

I have a gasoline tank with 46 m diameter and 13 m height. two row of coils are located near the bottom of the tank. the initial temperature of gasoline is -5 C. By this Coils it should be heated to 9 C. the coils flux is come from steam which is flows through the inner side of the coils. the coils length is 200 m with spiral shape. the coils diameter is 115 mm.

in fact the gasoline is heated by free convection. the flow regime is turbulent. (Ra > 10^9) I have set fixed temperature of ambient for B.C of the tank walls (side walls, bottom wall and top wall).

Sincerely
Hamid

 February 22, 2014, 21:10 Value of Q #4 Member   Abhijeet Shrawage Join Date: Feb 2012 Posts: 31 Rep Power: 14 As the previous poster suggested...maybe try recalculating the value of the heat flux applied. you have dT of 14C. You know the surface area of the heat source (heating coil). Use the simple formula. q=*Cp*T If Cp is varying, then substitute Cp with dH; the change in enthalpy of gasoline at -5C and 14C. If again you get the same answer, then try double checking if you have put the right thermophysical properties of Gasoline in your FLUENT material database. Things like low Cp or high thermal conductivity can be the cause of this as well. Best of Luck. Abhijeet