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Radiant Cooling CFD (Different Substrates)

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03/13/2018 7:06 AM

Hi all,

I've seen the recent thread regarding simulating the effects of radiant cooling and heating in a room, but I have a different set of studies i'd like to model. Essentially i'm trying to understand the interactions of different materials with an aluminum radiant panel used for heating and cooling (top layer of image below). The things i'd like to understand is heat transfer through various substrates (plywood, gypsum, etc) directly below a radiant panel located in the ceiling of a room. I'm guessing the initial heat transfer is through conduction until steady-state is achieved, and then by radiation towards the ambient air interior condition. Another condition i'd like to model is the  radiant panel with various thicknesses of air gaps below the panel, and a textile finish suspended below this (with various transmissivity and emissivity values). My intuition tells me this may affect the natural convection that occurs in the space as well.



Design 1
Created a volume and assigned it an air material (with variable setting on for natural convection). I then applied the aluminum material to the top face, and a glass wool material to sides and bottom. For BC's I applied a temperature BC to top aluminum face at 40deg Fahrenheit, and a film coefficient to the sides and bottom (3.5 BTU/ft2/h/R, 85 Fahrenheit).

Design 2
For this version I modeled a 1/8" plane and placed it underneath the top surface. All sides of the main volume have a film coefficient applied to them and are glass wool materials. The volume is unchanged as an air material. I then applied aluminum to the 1/8" plane and gave it a temperature boundary condition on all faces of 40 Fahrenheit. The result is the image below.


Screenshot_1.pngRadiant PanelDesign 1 - Radiant Panel Top Air.pngDesign 1Design 2 - Radiant Panel Top Individual.pngDesign 2

 Which one of these approaches represents the model i'm looking for? I'd like to know this before adding additional finishes below and doing the transmissivity tests. I've attached my file for those interested in taking a peek.



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Re: Radiant Cooling CFD (Different Substrates)

03/14/2018 12:53 AM

Just realized I posted the .cfdst instead of the .cfz 

Attached is the correct file - any help is appreciated!

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