 # Heat transfer coefficient in Solid domain

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• Last Post 26 September 2018
hamda posted this 25 September 2018

Hi there,

In my problem, I have defined 2 domains; solid domain (spheres) and fluid domain (the space between them).
In sub domain in solid domain  I have defined heat source. Indeed each sphere is a fuel element. Now I have a problem with boundary condition in solid domain (fuel domain).  As you can see in the following picture there are several spheres (fuel elements)  and in boundary conditions in Heat Transfer section, I don't know which option is the best  to my problem. I selected "heat transfer coefficient " but there is a problem to define "coefficient" and  outside temperature.  I have the value of power density so I can calculate the energy for each sphere and also for all spheres. My problem is in order to calculate "heat transfer coefficient" should I consider all spheres? or I should consider each sphere and calculate its thermal resistance? Attached Files

abenhadj posted this 25 September 2018

Does it look if you have totally submerged spheres in your fluids but some fractions of sphere pointing to the outer? The walls of the outer can be set to Robin B.C with ambient temperature and HTC from standard engineering book if the spheres are suspended in air (5-20 W/m^2K). But I think that you have in reality spheres submerged in your moderator and that you are simplifying the geometry: is this true? What about applying symmetry or periodic conditions? What about building up the simplified model with only fluid outer walls bounding a certain number of spheres? Perhaps other community member might chime in here.

Best regards, Amine

hamda posted this 26 September 2018  