Designing coaxial ground heat exchangers with a thermally enhanced outer pipe.

Raymond, Jasmin, Mercier, Serge et Nguyen, Luc (2015). Designing coaxial ground heat exchangers with a thermally enhanced outer pipe. Geothermal Energy , vol. 3 , nº 1. p. 1-14. DOI: 10.1186/s40517-015-0027-3.

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Résumé

Background

Ground heat exchangers installed in boreholes are an expensive component of a ground-coupled heat pump system, where minimizing the borehole length with appropriate materials and configuration can reduce the overall cost of the system.

Methods

Design calculations performed analytically indicate that the coaxial pipe configuration can be more advantageous than the single U-pipe configuration to reduce the total borehole length of a system.

Results

A decrease of the borehole thermal resistance and an increase of the thermal mass of water contained in the coaxial exchanger helped to reduce borehole length by up to 23% for a synthetic building load profile dominated by cooling. The decrease of the borehole thermal resistance was achieved with an outer pipe made of thermally enhanced high-density polyethylene, where the thermal conductivity is 0.7 W m⁻¹ K⁻¹.

Conclusions

The coaxial configuration requires further investigations of the technical barriers related to the installation of ground heat exchangers in the field.

Type de document:	Article
Mots-clés libres:	geothermal; heat pump; ground heat exchanger; borehole; coaxial; concentric; pipe; thermally enhanced
Centre:	Centre Eau Terre Environnement
Date de dépôt:	23 avr. 2018 19:14
Dernière modification:	27 nov. 2019 15:03
URI:	https://espace.inrs.ca/id/eprint/3923

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