Coaxial steel energy piles

摘要

A decisive part of the energy transition is the heat transition in the building sector. Heat pumps are a key element here. They need a heat source from which they can extract energy to transform it to a higher temperature level. This heat source can be, for example, the ground, whose heat can be extracted of geothermal probes. In this paper, coaxial probes integrated in steel piles are compared with the state of the art in ground probes of the same diameter regarding their thermal performance. In addition to heat extraction, steel energy piles offer further advantages, as they can also assume a static function and can be dismantled without leaving any residues. Analytical and numerical calculations are presented to compare the thermal potentials of both systems. In addition, a test setup is shown in which steel energy piles in two different lengths can be compared with existing common borehole heat exchangers. The calculations show a significant thermal surplus of between 26 and 148 of the steel energy piles compared to the state of the art, depending on the soil. The measurement results show an additional thermal yield of over 100 . This means that a significant length of borehole heat exchanger can be saved. It should be noted that this reduces the thermally utilized area of the ground, which makes thermal regeneration and/or the long-term behavior of the ground more important.