Energy Balance problem

masud · May 9, 2012, 08:37

Hi everyone
After ive finished running my simulation I did some checking, and found out that the Energy is not balanced even if the simulation converged.

Im simulating a asphalt solar collector and the model made of four parts. There are thre layers of asphalt(0.5mx0.25m) and a pipe where water flows inn it in the centre the asphalt layer in the middle.

The solar flux is coming inn at the top og the first layer of asfalt.
Any ideas?

Thanks for your answer

ping · May 23, 2012, 10:15

sounds like you are only looking at residuals - you should always be monitoring some reports of key measurements like temperature and energy balance in a heat transfer case to ensure convergence. if your model has solids then set the solid energy under-relaxation to a very high number - the default is 0.99, but you should use 0.9999 or above and 1.0 works in many cases - this speeds convergence by many times.

May 9, 2012, 08:37	Energy Balance problem	#1
masud New Member Join Date: Apr 2012 Posts: 3 Rep Power: 13	Hi everyone After ive finished running my simulation I did some checking, and found out that the Energy is not balanced even if the simulation converged. Im simulating a asphalt solar collector and the model made of four parts. There are thre layers of asphalt(0.5mx0.25m) and a pipe where water flows inn it in the centre the asphalt layer in the middle. The solar flux is coming inn at the top og the first layer of asfalt. Any ideas? Thanks for your answer

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May 23, 2012, 10:15		#2
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	sounds like you are only looking at residuals - you should always be monitoring some reports of key measurements like temperature and energy balance in a heat transfer case to ensure convergence. if your model has solids then set the solid energy under-relaxation to a very high number - the default is 0.99, but you should use 0.9999 or above and 1.0 works in many cases - this speeds convergence by many times.