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Bd. 1 (2023): GeoTHERM Journal

Fast Calculation Method for Borehole Heat Exchanger Fields in Groundwater Flow

Oktober 3, 2023


One class of methods for the design of borehole heat exchanger fields is the use of analytical, non-dimensional thermal step responses, such a g-functions. A main simplification and restriction of most existing analytical tools for BHE design is the neglection of groundwater advection. The theory and concept of moving line sources can, in principle, be used to calculate the thermal behaviour of BHEs in groundwater flow.

However, application of the moving line source to grouted boreholes needs a correction for the disturbance of the groundwater flow field and the lower heat transfer rates in the borehole region. Based on such a correction developed and published earlier, the applicability of the infinite moving line source model on whole borehole fields is shown in this paper by comparison with numerical simulation. Together witch spatial superposition of the long-term temperature responses and influences, fields of arbitrarily placed borehole heat exchangers can be calculated. This yields an analytical, simple and fast calculation methods for borehole heat exchanger fields, when sufficient the groundwater flow is present over the hole depth of the boreholes.

A design example is presented, in which one of three borehole heat exchangers can be saved when a significant groundwater flow is present and taken into account.