Formulation of a 1D finite element of heat exchanger for accurate modelling of the grouting behaviour: Application to cyclic thermal loading
Formulation of a 1D finite element of heat exchanger for accurate modelling of the grouting behaviour: Application to cyclic thermal loading
This paper presents a comprehensive formulation of a finite element for the modelling of borehole heat exchangers. This work focuses on the accurate modelling of the grouting and the field of temperature near a single borehole. Therefore the grouting of the BHE is explicitly modelled. The purpose of this work is to provide tools necessary to the further modelling of thermo-mechanical couplings. The finite element discretises the classical governing equation of advection-diffusion of heat within a 1D pipe connected to ground nodes. Petrov-Galerkin weighting functions are used to avoid numerical disturbances. The formulation is able to capture highly transient and steady-state phenomena. The proposed finite element is validated with respect to analytical solutions. An example consisting of a 100 m depth U-pipe is finally simulated. A first continuous heating simulation highlights the nonsymmetric distribution of temperature inside and near the borehole. An estimation of the error on the results as a function of the resolution parameters is also carried out. Finally simulations of cyclic thermal loading exhibit the need to take into account all daily variations if the grouting behaviour must be modelled. This is true especially in case of freeze-thaw damaging risk.
Borehold heat exchanger, Ground source heat pump, Finite element, Short-time step, Numerical modelling
65-79
Cerfontaine, Benjamin
0730daf4-9d6b-4f2d-a848-a3fc54505a02
Radioti, Georgia
f8886b45-0737-4bf4-8332-f3fe4a4f060e
Collin, Frédéric
27fa6a2d-f8e2-473f-a3b2-070eca6a9c3a
Charlier, Robert
3bba8221-b05d-431a-8a41-40f1b5dcc7e8
October 2016
Cerfontaine, Benjamin
0730daf4-9d6b-4f2d-a848-a3fc54505a02
Radioti, Georgia
f8886b45-0737-4bf4-8332-f3fe4a4f060e
Collin, Frédéric
27fa6a2d-f8e2-473f-a3b2-070eca6a9c3a
Charlier, Robert
3bba8221-b05d-431a-8a41-40f1b5dcc7e8
Cerfontaine, Benjamin, Radioti, Georgia, Collin, Frédéric and Charlier, Robert
(2016)
Formulation of a 1D finite element of heat exchanger for accurate modelling of the grouting behaviour: Application to cyclic thermal loading.
Renewable Energy, 96 (Part A), .
(doi:10.1016/j.renene.2016.04.034).
Abstract
This paper presents a comprehensive formulation of a finite element for the modelling of borehole heat exchangers. This work focuses on the accurate modelling of the grouting and the field of temperature near a single borehole. Therefore the grouting of the BHE is explicitly modelled. The purpose of this work is to provide tools necessary to the further modelling of thermo-mechanical couplings. The finite element discretises the classical governing equation of advection-diffusion of heat within a 1D pipe connected to ground nodes. Petrov-Galerkin weighting functions are used to avoid numerical disturbances. The formulation is able to capture highly transient and steady-state phenomena. The proposed finite element is validated with respect to analytical solutions. An example consisting of a 100 m depth U-pipe is finally simulated. A first continuous heating simulation highlights the nonsymmetric distribution of temperature inside and near the borehole. An estimation of the error on the results as a function of the resolution parameters is also carried out. Finally simulations of cyclic thermal loading exhibit the need to take into account all daily variations if the grouting behaviour must be modelled. This is true especially in case of freeze-thaw damaging risk.
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More information
Accepted/In Press date: 19 April 2016
e-pub ahead of print date: 3 May 2016
Published date: October 2016
Keywords:
Borehold heat exchanger, Ground source heat pump, Finite element, Short-time step, Numerical modelling
Identifiers
Local EPrints ID: 444201
URI: http://eprints.soton.ac.uk/id/eprint/444201
ISSN: 0960-1481
PURE UUID: 0034e20a-1b86-4ad8-9b3c-559fbaaa4e3b
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Date deposited: 01 Oct 2020 16:34
Last modified: 17 Mar 2024 04:02
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Contributors
Author:
Georgia Radioti
Author:
Frédéric Collin
Author:
Robert Charlier
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