The effect of the infinite length approximation on evaluating the temperature Tb of the external surface of Borehole Heat Exchangers (BHEs) is determined by means of COMSOL Multiphysics (© COMSOL AB.). In detail, two 2D models of a BHE are compared: in the first model, the computational domain is represented by a cross-section of the geometry, where the BHE is replaced by a hole subjected to a constant heat flux. In the second model, the computational domain is represented by an axial-section of the geometry and, thus, the actual length of the BHE is considered. Also in this case, the internal structure of the BHE is not modeled and a constant heat flux on its surface is prescribed. 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.
Comparison of 2D Conduction Models for Vertical Ground Coupled Heat Exchangers / A. Priarone; S. Lazzari. - ELETTRONICO. - (2011), pp. 1-5. (Intervento presentato al convegno COMSOL Conference 2011 Stuttgart tenutosi a Stuttgart, Germany nel October 26-28, 2011).
Comparison of 2D Conduction Models for Vertical Ground Coupled Heat Exchangers
LAZZARI, STEFANO
2011
Abstract
The effect of the infinite length approximation on evaluating the temperature Tb of the external surface of Borehole Heat Exchangers (BHEs) is determined by means of COMSOL Multiphysics (© COMSOL AB.). In detail, two 2D models of a BHE are compared: in the first model, the computational domain is represented by a cross-section of the geometry, where the BHE is replaced by a hole subjected to a constant heat flux. In the second model, the computational domain is represented by an axial-section of the geometry and, thus, the actual length of the BHE is considered. Also in this case, the internal structure of the BHE is not modeled and a constant heat flux on its surface is prescribed. 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
