Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Värmeöverföring i bergvärmesystem: En numerisk analys av den ringformade koaxiala borrhålsvärmeväxlaren
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2012 (Swedish)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesisAlternative title
Heat transfer in ground source heat pump systems : A numerical analysis of the annular coaxial borehole heat exchanger (English)
Abstract [en]

The borehole heat exchangers of today suffer from poor thermal and hydrodynamic performance. The purpose of this thesis is to improve the performance of ground source heat pump systems and thermal energy storages by increasing the energy efficiency of the borehole heat exchangers. For this reason, the annular coaxial borehole heat exchanger (CBHE) has been analyzed. This type of heat exchanger is interesting in terms of both thermal and hydrodynamic performance. A model has been set up in the program Comsol Multiphysics in order to investigate the heat transfer characteristics along the borehole. A literature survey that summarizes the analytical calculation methods developed in earlier Swedish research is presented in the report. Different geometries with or without insulation of the central pipe have been analyzed and the effective borehole resistance for each geometry has been calculated based on the simulation results. The model has been validated against a recently performed thermal response test, and shows very good correlation with reality. The results from the simulations show that by using the annular CBHE an increase of 2-3 °C in the evaporator of the heat pump can be achieved. Calculations show that the pump work (head loss) can be reduced to 1/6 of the corresponding case with a single U-pipe. There arises a vertical temperature gradient in the bedrock when recharging and extracting heat with the annular CBHE. This means that the annular CBHE acts like a counter-flow heat exchanger which is thermally optimal. In total, the simulation result shows that the annular CBHE geometry in this thesis can increase a system's seasonal performance factor (SPF) with 10-19 % in comparison with a U-pipe BHE. This is equivalent to 10-19 % lower electrical power consumption every year.

Place, publisher, year, edition, pages
2012. , 92 p.
Series
UPTEC ES, ISSN 1650-8300 ; 12016
Keyword [en]
annular coaxial borehole heat exchanger, ground source heat pump, BHE, CBHE, thermal borehole resistance
Keyword [sv]
Koaxial borrhålsvärmeväxlare, borrhålsmotstånd, värmepump, bergvärme, bergkyla, termisk prestanda
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:uu:diva-176915OAI: oai:DiVA.org:uu-176915DiVA: diva2:537799
Educational program
Master Programme in Energy Systems Engineering
Uppsok
Technology
Supervisors
Examiners
Available from: 2012-08-08 Created: 2012-06-27 Last updated: 2012-08-08Bibliographically approved

Open Access in DiVA

fulltext(4405 kB)697 downloads
File information
File name FULLTEXT01.pdfFile size 4405 kBChecksum SHA-512
157cc743ec2c87a9774d120addbf80fa2a22fcea8a29543266e8f63c7803f98778ef2ddcc42fef49f1e743752e53ef59bca4907fe722b767ed33d65becac8ed8
Type fulltextMimetype application/pdf

By organisation
Electricity
Energy Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 697 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 961 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf