Thermal performance assessment of closed-loop geothermal heat exchangers with vertical, inclined, and curved boreholes

M. Hermanns, J. Rico, S.E. Ibáñez, Y. Goitia

1st Geothermal Research and Innovation Network Conference - Geo-RIN, Huesca (Spain). 02-06 June 2025

Summary:

Accurate sizing of closed-loop geothermal heat exchangers is crucial to ensuring the energy efficiency and cost-effectiveness of shallow geothermal HVAC systems. One common design limitation is the restricted surface area available for borehole drilling. To address this constraint, inclined and curved borehole configurations offer an alternative to conventional vertical ones, allowing a greater underground exchange volume without increasing the ground footprint. However, inclined —and especially curved—boreholes involve higher drilling costs, raising the question of whether thermal performance justifies the investment. This study assesses the thermal behavior of closed-loop geothermal heat exchangers with vertical, inclined, and curved borehole configurations. Results show that inclined configurations represent the best balance between thermal efficiency and economic feasibility among the three.

Spanish layman's summary:

El estudio compara intercambiadores geotérmicos con perforaciones verticales, inclinadas y curvas. Concluye que las inclinadas ofrecen el mejor equilibrio entre eficiencia térmica y costo, optimizando el uso del terreno sin incrementar demasiado la inversión.

English layman's summary:

This study compares vertical, inclined, and curved geothermal boreholes. Results show that inclined designs achieve the best balance between thermal efficiency and drilling cost, maximizing underground heat exchange without requiring extra surface area.

Keywords: geotermia somera, pozos inclinados, pozos curvos, rendimiento térmico

Published in: Geo-Temas, vol. 21, pp: 27-30, ISSN: 1576-5172

Publication date: 06-Jun-2025.

Citation:
M. Hermanns, J. Rico, S.E. Ibáñez, Y. Goitia, "Thermal performance assessment of closed-loop geothermal heat exchangers with vertical, inclined, and curved boreholes", presented at 1st Geothermal Research and Innovation Network Conference - Geo-RIN, Huesca, Spain, 02-06 June 2025. In: Geo-Temas, vol. 21, pp. 27-30

IIT-25-298C