Modeling the thermal interaction of geothermal boreholes with aquifers using asymptotic expansion techniques

To design an optimally-sized geothermal heat exchanger it is crucial to accurately forecast its thermal response over the whole lifetime of the building. Since the presence of aquifers highly affects the heat exchange between geothermal boreholes and the ground, both heat transfer mechanisms, conduction and convection, must be taken into account in the ground. In the present work the existence of large disparities in time and length scales in the problem is exploited using asymptotic expansion techniques to develop a theoretical model capable of taking into account both aforementioned heat transfer mechanisms for any Peclet number of the groundwater flow.