Performance Evaluation of Ground Coupled Heat Pump System Using Heat Injection Test Analysis

N Jaziri

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: GROUNDWATER AND HYDROGEOLOGY - I Groundwater Hydraulics

ABSTRACT: Geothermal heat pump systems provide a better energy efficiency and a lower operating cost compared to conventional heating and cooling systems. Such a closed loop geothermal system was installed at the Carignan-Salières school to the south shore of Montreal to heat and cool the building in operation since October 2013. The system encloses 31 vertical ground heat exchangers having an approximate depth of 152 m. The boreholes were backfilled with synthetic olivine sand instead of a geothermal grout as specified in the design plans because the fine grout particles were washout by groundwater flow. These changes in filling material and the variable groundwater flow setting can have an impact on the long-term performance of the system. A study was realized, using a model calibrated with a heat injection test conduct on the whole borehole field, to predict the performance of the ground heat exchangers and simulate numerically the water temperature entering the heat pumps for twenty years according to different scenarios, depending essentially on the thermal conductivities of the subsurface and the filling material. The simulation results have shown that the effective thermal conductivity of the subsurface affected by groundwater flow has a more important impact on the ground heat exchanger performance than the thermal conductivity of the filling material.

RÉSUMÉ: Les systèmes de pompes à chaleur géothermique offrent une meilleure efficacité énergétique et un faible coût -Salières sur la Rive Sud de Montréal, un système géothermique à boucle fermée a été installé pour assurer le chauffage et la e souterraine pourraient avoir uprédire la performance des échangeurs de chaleur pompes à chaleur sur une période de vingt ans selon différents scénarios qui dépendent essentiellement des conductivités thermiques du sous-sol et des matériaux de remplissage. Les résultats ont montré que la conductivité thermique effective du sous-échangeurs de chaleur que la conductivité thermique des matériaux de remplissage.

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