Stockage thermique saisonnier dans un champ de puits geothermiques verticaux en boucle fermee

A new closed-loop vertical geothermal heat exchanger model is proposed for use within the TRNSYS environment. Two main features distinguish this model from other models. It allows the study of borefields where the spatial position of each borehole is defined by the user and where two independent borehole networks can be modeled (one working in charge mode while the other one is in discharge mode, for example). The proposed model relies on the finite-line source method coupled with spatial and temporal superposition techniques to represent the unsteady heat transfert process occuring in the ground. The proposed model is successfully validated by comparison with seven experimental cases. In addition, its results are compared to those of the DST model.;Practical applications with the proposed model and with the modified DST model are presented as part of complex heating and cooling systems of buildings using thermal storage in the ground with solar recharging. The proposed model is also used to model the four pipes forming the two U-tubes inside a single borehole where each U-tube is part of an independent network.;This study demonstrates that the proposed model correctly simulates the evolution of the fluid temperature at the outlet of a geothermal heat exchanger. Thus, it is recommended to use the proposed model instead of the DST model, especially when the boreholes to be modeled are not uniformly distributed around the center axis of the storage volume.;In another part of this study, the calculation methods from a reference model, the DST model, are brought to light. The limitations of the DST model are demonstrated by comparison to the proposed model. The DST model is inappropriate when the boreholes to be modeled are not uniformly placed around the center axis of the storage volume. In addition, a problem of discontinuity in the evolution of the calculated fluid outlet temperature from the DST model is also shown. A brief section explains how the DST model source code has been modified to consider configurations with two independent networks of U-tubes where each borehole contains one U-tube from each network. This modification enables to study the behavior of low temperature storage and improved thermal storage operation.