Comparison between 2D and 3D simulations

Hallo,

I'm Daniele. I'm dealing with an interesting question about the difference between a 2D and 3D model. I simulated a Borehole Heat Exchanger. I started with the 2D and than I created the 3D from this one, the difference is the quantity of energy that I keep out. To calculate this one I multiply the quantity of the 2D (2,5 milions J/d/m) for the depth of the Heat exchanger (2,5 x 10 m). I expected to have similar results but temperature in the Heat exchanger 3D is really higher.

If someone has already worked on such simulations and has any suggests I would be really gratefull

Thanks

Daniele