Influence of BHE on subsurface temperature

Hi everyone,

I am simulating the operation of a deep borehole heat exchanger (BHE) with FEFLOW 7.2. I have run two different scenarios where the [u]only[/u] changed parameter is the circulation rate of the BHE. Now, looking at cross sections of the temperature field, it looks as if the disturbance of the temperature near the BHE is [u]greater[/u] in the scenario with the lower circulation rate (please see attached picture). This is not what I expected. Shouldn't a higher circulation rate extract more heat from the subsurface, i.e. cause a larger decrease in temperature near the BHE?

I would be very happy if you could give me any advice on where my understanding might be wrong or what may cause this effect in the model.

Thanks,
wiko

Hi again,

The issue is resolved. The root cause must've been a suboptimal temporal discretization. I've set a maximum growth for the time-steps, lowered the error criterion and reduced the number of iterations to 1. Since then, the results are more like what I expected.

Thanks,
wiko