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

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216305%3A26210%2F24%3APU156126" target="_blank" >RIV/00216305:26210/24:PU156126 - isvavai.cz</a>

Result on the web

<a href="https://academic.oup.com/ijlct/article/doi/10.1093/ijlct/ctae132/7750401" target="_blank" >https://academic.oup.com/ijlct/article/doi/10.1093/ijlct/ctae132/7750401</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/ijlct/ctae132" target="_blank" >10.1093/ijlct/ctae132</a>

Result language

angličtina

Original language name

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

Original language description

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.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

20303 - Thermodynamics

Project

—

Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

International Journal of Low Carbon Technologies

ISSN

1748-1317

e-ISSN

—

Volume of the periodical

19

Issue of the periodical within the volume

1

Country of publishing house

GB - UNITED KINGDOM

Number of pages

18

Pages from-to

2068-2085

UT code for WoS article

001306644200001

EID of the result in the Scopus database

2-s2.0-85203627557