heat transfer in solar air heater

arunachalam.siva · January 27, 2010, 03:02

Hi friends
I am a new user of cfd forum.
I want to analysis solar air heater in fluent.
I designed solar air heater with fins in gambit.
I apply heat flux in underside of the absorber plate.
I split the solid from fluid volume in gambit.
I analysed this problem in fluent and i got a result.
But when i increase a inlet velocity the base temperature reduced at the same time outlet temerature also reduced.
Our aim is increase outlet temperature with increse in inlet velocity.
Anybody help me for tactle this problem.

tony00 · March 1, 2010, 14:20

Hi,
I would do an energy balance of your system: Energy in = Energy out.
Energy in:
1) Your heat flux times area
2) total enthalpy of the incoming air

Energy out:
1) total enthalpy of the heated air

You will see that your results are consistent: for a higher flow rate (you specified higher velocity) you get lower temperature out.

To optimise your solar collector I would recommend you use natural convection model ( you can either use boussinesq or define a temperature dependent air density, first option is best).

Regards

arunachalam.siva · March 3, 2010, 03:07

Thank u for ur reply
I have another doubt
I apply heat flux in base side of the plate
Our sir told apply heat flux in base the temperature of the base only reduce but the temperature of the air does not increase.
Is it right please explain me?

ram_call · April 17, 2013, 15:43

of course as u increase inlet velo, temp will fall in outlet

January 27, 2010, 03:02	heat transfer in solar air heater	#1
arunachalam.siva New Member A.Siva Arunachalam Join Date: Aug 2009 Posts: 3 Rep Power: 17	Hi friends I am a new user of cfd forum. I want to analysis solar air heater in fluent. I designed solar air heater with fins in gambit. I apply heat flux in underside of the absorber plate. I split the solid from fluid volume in gambit. I analysed this problem in fluent and i got a result. But when i increase a inlet velocity the base temperature reduced at the same time outlet temerature also reduced. Our aim is increase outlet temperature with increse in inlet velocity. Anybody help me for tactle this problem.

March 1, 2010, 14:20	Energy balance previous to CFD	#2
tony00 New Member Join Date: Nov 2009 Posts: 22 Rep Power: 17	Hi, I would do an energy balance of your system: Energy in = Energy out. Energy in: 1) Your heat flux times area 2) total enthalpy of the incoming air Energy out: 1) total enthalpy of the heated air You will see that your results are consistent: for a higher flow rate (you specified higher velocity) you get lower temperature out. To optimise your solar collector I would recommend you use natural convection model ( you can either use boussinesq or define a temperature dependent air density, first option is best). Regards

March 3, 2010, 03:07	Thank u	#3
arunachalam.siva New Member A.Siva Arunachalam Join Date: Aug 2009 Posts: 3 Rep Power: 17	Thank u for ur reply I have another doubt I apply heat flux in base side of the plate Our sir told apply heat flux in base the temperature of the base only reduce but the temperature of the air does not increase. Is it right please explain me?

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April 17, 2013, 15:43		#4
ram_call Member ram Join Date: Apr 2013 Posts: 37 Rep Power: 13	of course as u increase inlet velo, temp will fall in outlet