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Simulation of a sollar collector

Posted Nov 24, 2012, 7:05 a.m. EST Fluid & Heat, Heat Transfer & Phase Change, Parameters, Variables, & Functions, Results & Visualization Version 4.3 3 Replies

Vincent Gig
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Hi everyone

I'm a French engineering student and I need to simulate a solar collector in COMSOL multiphysics.
I build the panel with glass, air gap, copper, water and insulation but I have a problem with the simulation.
When I start the simulation there is a problem because the temperature of water does not increase.
In fact, the temperature increase only on the airgap.

Who can help me please?

Vincent
3 Replies Last Post Nov 24, 2012, 12:56 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 24, 2012, 8:20 a.m. EST
Hi

you havce a multifluid solid + radiation heat transfer I understand, bt you need to tell us a bit more how you consider these fluids, static, equation flow ... And if you do not get a heat transfer from one state to the other it is probably because you have not defined the interfaces fully. In such a model you need to consider each pysics and on each domain anc chack that all required BC and physics couplings are there.

To start somewhere: are you modelling the air flow by convection ? or only by conduction ?

--
Good luck
Ivar
Hi you havce a multifluid solid + radiation heat transfer I understand, bt you need to tell us a bit more how you consider these fluids, static, equation flow ... And if you do not get a heat transfer from one state to the other it is probably because you have not defined the interfaces fully. In such a model you need to consider each pysics and on each domain anc chack that all required BC and physics couplings are there. To start somewhere: are you modelling the air flow by convection ? or only by conduction ? -- Good luck Ivar
Vincent Gig
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Posted: 1 decade ago Nov 24, 2012, 11:41 a.m. EST
I decided to model my collector in static
I put a glass on top, next I draw the air gap and I take the properties of the air in cosmos materials. And I draw the model as you can see in the document attached.
I decided to model my collector in static I put a glass on top, next I draw the air gap and I take the properties of the air in cosmos materials. And I draw the model as you can see in the document attached.

Attachments:

Jonathan Proud'hom
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Posted: 1 decade ago Nov 24, 2012, 12:56 p.m. EST
Hi Ivar and everyone else,

I am Jonathan and I work with Vincent on this project. The picture Vincent has just added (pdf document) sums up perfectly our system.
Air and water were defined as fluids.
We started a stationary study. We noticed that the temperature of the water does not increase. In fact the temperature stops increasing in the middle of the air gap.
I guess that this problem is due to interfaces. We do not know what conditions we need to impose on these one (We have not imposed anything in fact). In the air gap it is supposed to have radiant heating due to multiple reflections of sun rays. There should be convection and conduction I suppose.

Do we have to use different physics? For the moment we have just used “Conjugate heat transfer” in the case of “Laminar flow”.

Thanking you in advance

Jonathan
Hi Ivar and everyone else, I am Jonathan and I work with Vincent on this project. The picture Vincent has just added (pdf document) sums up perfectly our system. Air and water were defined as fluids. We started a stationary study. We noticed that the temperature of the water does not increase. In fact the temperature stops increasing in the middle of the air gap. I guess that this problem is due to interfaces. We do not know what conditions we need to impose on these one (We have not imposed anything in fact). In the air gap it is supposed to have radiant heating due to multiple reflections of sun rays. There should be convection and conduction I suppose. Do we have to use different physics? For the moment we have just used “Conjugate heat transfer” in the case of “Laminar flow”. Thanking you in advance Jonathan

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