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Temperaturzoner för lagring av värmeenergi i cirkulärt borrhålsfält
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
2013 (Swedish)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Temperature stratification of borehole thermal energy storages (English)
Abstract [en]

The thermal response of a borehole field is often described by non‐dimensional response factors called gfunctions.The g‐function was firstly generated as a numerical solution based on SBM (Superposition BoreholeModel). An analytical approach, the FLS (Finite Line Source), is also accepted for generating the g‐function. In thiswork the potential to numerically produce g‐functions is studied for circular borehole fields using the commercialsoftware COMSOL. The numerical method is flexible and allows the generation of g‐functions for any boreholefield geometry. The approach is partially validated by comparing the solution for a square borehole field containing36 boreholes (6x6) with g‐functions generated with the FLS approach and with the program EED (Earth EnergyDesigner). The latter is based on Eskilsons SBM, one of the first documents where the concept of g‐functions wasintroduced. Once the approach is validated, the square COMSOL model is compared with a circular geometryborehole field developed by the same method, consisting of 3 concentric rings having 6, 12, and 18 boreholes.Finally the influence on the circular geometry g‐function is studied when connecting the boreholes in radial zoneswith different thermal loads.

Abstract [sv]

Den termiska responsen för ett borrhålsfält beskrivs ofta med den dimensionslösa responsfunktionen kallad gfunktion.Responsfunktionen togs först fram som en numerisk lösning med SBM (Superposition Borehole Model).En analytisk metod, FLS (Finite Line Source) är också accepterad för framtagandet av g‐funktioner. I det här arbetetundersöks förutsättningarna att numeriskt ta fram g‐funktioner för cirkulära borrhålsfält genom att använda detkommersiella simuleringsprogrammet COMSOL Multiphysics. Den numeriska metoden är flexibel och kananvändas för alla typer av borrhålsgeometrier. Metoden att använda COMSOL valideras delvis genom att jämföraresultatet för ett kvadratiskt borrhålsfält innehållande 36 borrhål (6x6) med lösningar framtagna med FLS och meddimensioneringsprogrammet EED (Earth Energy Designer). Det senare har sin grund i Eskilsons SBM, ett av deförsta arbeten där begreppet g‐funktion introducerades. När metoden att använda COMSOL verifierats, jämförsden kvadratiska borrhålsmodellen med en cirkulär borrhålskonfiguration, upprättad med samma metod,innehållande 3 koncentriska ringar om vardera 6, 12, 18 borrhål. Slutligen undersöks hur den termiska responsenpåverkas då borrhålen i ett cirkulärt borrhålsfält kopplas samman och grupperas i radiella zoner med olika termiskalaster.

Place, publisher, year, edition, pages
2013. , 31 p.
Keyword [en]
g-function, bore hole, thermal energy storage, EED, Earth Energy Designer, FLS, Finite Line Source, COMSOL, borehole thermal energy storage, ground source heat pumps, borehole heat exchanger
Keyword [sv]
g-funktion, geoeneri, borrhål, bergvärme, SEEC, COMSOL, EED, FLS, borrhålslager, Earth Energy Designer, berggrund
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-128951OAI: oai:DiVA.org:kth-128951DiVA: diva2:649067
Subject / course
Energy Technology
Educational program
Master of Science in Engineering - Mechanical Engineering
Presentation
2013-06-27, Energi biblioteket, Brinellvägen 68, Stockholm, 13:00 (English)
Supervisors
Examiners
Projects
SEEC Scandinavian Energy Efficiency Co.
Available from: 2013-09-23 Created: 2013-09-17 Last updated: 2013-09-23Bibliographically approved

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  • apa
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