Comparison of 2D Conduction Models for Vertical Ground Coupled Heat Exchangers

A. Priarone[1], and S. Lazzari[2]
[1]DIPTEM-TEC, Università di Genova, Genova, Italia; Corresponding Author: a.priarone@unige.it
[2]DIENCA, Università di Bologna, Bologna, Italia
Published in 2011

The effect of the infinite length approximation on evaluating the temperature of the surface of Borehole Heat Exchangers is determined by means of COMSOL Multiphysics. In detail, two 2D models of a BHE are compared: in the first model, the domain is represented by a cross-section of the geometry, while in the second model, it is represented by an axial-section of the geometry and, thus, the BHE length is considered.

In both cases, the BHE is replaced by a hole subjected to a constant heat flux. The discrepancies in Tb due to these two models are investigated as a function of time and a dimensionless correlation is proposed to estimate the error made by neglecting the BHE length.

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