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Analysis of an Existing Solar Thermal DHW System of a Multifamily House in Germany
Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
2015 (English)Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

This study was conducted to investigate operational problems of a larger solar thermal plant (> 100m²) supporting

domestic hot water (DHW) preparation. Already at the beginning of the 15 years of operation effective solar gains

fell beyond the T-SOL pre-simulated figures. In addition to that collectors were found leaking after 10 years. The

aim of the study was also to determine the causes for damaged collectors and to deliver improvement suggestions

if applicable. The solution was approached by a set of different methods. Literature review and analysis of plans,

notes and documents of the plant were accompanied by measurements and (re)-calculations and site visits.

Problems in different sectors of the plant were found. In the secondary circuit, the pump action of the heat

exchange station was permanent instead of a recommended on demand action. In terms of the DHW preparation

the lower DHW store sensor was placed in DHW circulation pipe instead of inside the store. In the primary circuit

the size of the expansion vessel was designed to small. The conception of the solar circuit and the application of

safety valving were not appropriate in terms of a partial evaporation system. Essential temperature differences

among collector cases could be attributed to incorrect assigned sensor characteristics in the system control panel.

Therefore the solar pump was not regulated well, which led to stagnation and overheating. The boiling of solar

fluid caused the safety valves to blow off and might have led to a loss of the fluids frost protection characteristics.

During the study, it was asserted that the system design as much as its implementation and maintenance (regularity

and intensity) were insufficient and led to irreversible plant damage. Different system improvements depending on

effort can be concluded from that. One example would be the adaption of layout of the existing system to the

requirements of a partial evaporation system whereas the number of collectors remains the same. Amongst others

the complete replacement of the plant is discussed.

Place, publisher, year, edition, pages
2015.
National Category
Environmental Engineering
Identifiers
URN: urn:nbn:se:du-17006OAI: oai:DiVA.org:du-17006DiVA: diva2:790283
Available from: 2015-02-24 Created: 2015-02-24

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CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • 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