Jozsef

Dear FEFLOW users,

I have read the posts on this forum trying to get some ideas with respect to the reference temperature. I am comparing the FEFLOW results for a pure conductive scenario with the SBM model which originally uses Eskilson and Claesson analytical solution. So for such scenario the results should be the same or at least pretty similar, but this is not the case.

Basically the problem is that I do not know how to assign the same energy extraction rates or equivalent ones in both models.  In order to assign the same load patterns I just followed Dr. Rühaak suggestion (previous post) using zero as a reference temperature. By doing this, I get the same input rate as in SBM, however, FEFLOW results are much more lower, around 2 K, than those form SBM. In addition, the input and output temp are pretty differents. (I am modelling a field with 25 BHE equally distributed)

Until now, it is not clear to me what exactly the reference temperature is. I have read Eskilson and Claesson paper and the FEFLOW white paper 5 and I can not find the physical interpretation of this parameter. In the SBM code the initial inlet pipe temperature is calculated by the code itself using kind of an optimization approach and not by a prescribed BC. Have somebody else already compared the FEFLOW BHE tool with the SBM code? What is the subsequent calculation for the heat extraction rates mentioned previously in this post? Is there a reference of this calculation on the corresponding white paper?

I have not tried the IFM plug in, I just sent an email some minutes ago to WASY, maybe with this I could get rid of this problem or understand how the BHE tool really works.

Thanks in advance

Jozsef