Detail publikace

Performance of vacuum-insulated central pipes for deep borehole heat exchangers in geothermal systems

KUBAČKA, J. KARAYIANNIS, T.

Originální název

Performance of vacuum-insulated central pipes for deep borehole heat exchangers in geothermal systems

Typ

článek v časopise ve Web of Science, Jimp

Jazyk

angličtina

Originální abstrakt

Geothermal energy is considered a promising future energy prospect, with the geothermal well outlet temperature being one of the important parameters affecting possible utilization options. For ground source heat pump applications or direct district heating, using lower temperatures can be acceptable. However, efficient electricity production requires a higher enthalpy gradient, which cannot be achieved without high temperature at the wellhead. The selection of the dry co-axial close-loop deep borehole systems (DBHE) may be, in some cases, very beneficial. The operating performance of co-axial DBHE can be optimized if the undesired heat transfer between the central pipe and annular fluid zones is minimized. Therefore, the operational performance of such a system depends strongly on the high thermal resistance of the central pipe. The most common option would be a low thermal conductivity material, such as high-density polyethylene (HDPE). In addition, vacuum-insulated tubing (VIT) used as the central pipe could be considered. The article presents results from the study aimed at the comparison of the homogeneous central pipe made of HDPE material and the gap-insulated central pipe. In the study, various air pressure levels as well as variations of surface emissivity were examined to reveal the effect on the heat transfer between the fluid channels. The simulation has been performed using a new purposely developed WellTH simulation software. A coaxial heat exchanger system using a VIT outperforms significantly the heat exchanger with an HDPE for deep geothermal wells. However, this advantage diminishes for shallow wells and therefore this tendency should be considered in the design stage.

Klíčová slova

geothermal energyco-axial heat exchangerclosed-loop systemvacuum-insulated central pipe

Autoři

KUBAČKA, J.; KARAYIANNIS, T.

Vydáno

6. 9. 2024

Nakladatel

Oxford University Press

Místo

Oxford, GB

ISSN

1748-1317

Periodikum

International Journal of Low Carbon Technologies

Ročník

19

Číslo

1

Stát

Spojené království Velké Británie a Severního Irska

Strany od

2068

Strany do

2085

Strany počet

18

URL

https://academic.oup.com/ijlct/article/doi/10.1093/ijlct/ctae132/7750401

Plný text v Digitální knihovně

http://hdl.handle.net/11012/250697

BibTex

@article{BUT197379,
  author="Ján {Kubačka} and Tassos G. {Karayiannis}",
  title="Performance of vacuum-insulated central pipes for deep borehole heat exchangers in geothermal systems",
  journal="International Journal of Low Carbon Technologies",
  year="2024",
  volume="19",
  number="1",
  pages="2068--2085",
  doi="10.1093/ijlct/ctae132",
  issn="1748-1317",
  url="https://academic.oup.com/ijlct/article/doi/10.1093/ijlct/ctae132/7750401"
}