Design and Monitoring of borehole heat exchangers using distributed

temperature measurements

KTH Royal Institute of TechnologyJosé Acuña

www.svepinfo.sewww.pemtec.se

Fiber inne i borrhålen

TnTn‐1

T1 T2        T3 T4 ……….

Distributed Temperature Sensing

DTS Instrument

DTS Instrument

Measurement example: U-pipe BHEs

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Djup

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Temperatur [C]

0,5 l/s0,4 l/s0,2 l/s0,14 l/s

Dep

th[m

]

time[°C] 0

260

Measurement example: DTRT

Example of results from DTRT

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2.5 3 3.5Djup

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λberg [W/mK]

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Värmelednings förmåga [ W/mK] 

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Dju

p [

m]

Temperatur [°C]

Stockholms University

130 boreholes230 m deep

Winter: 1400 kW2,5 / 6,0 ºC

Summer: 2500 kW31 / 25 ºC

Hesselmannskastiftelsen

How to include DTS in design and monitoring of large bore fields ?

Installationsite

Optical fiber cables outside the BHE pipes

Some g-functions in zone 12

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g‐functio

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ln (9FoH)

Single borehole

Two boreholes

Manifold 12

Whole Installation

Theory and practice

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Temperatur [C]

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m]

Temperatur [°C]

Measured data vs.models byPatricia Monzóand Alberto Lazzarotto

First DTRT: Frescati

Preliminary results

KTH team: FRESCATI PROJECT

KTH energiteknikKTH byggnadsteknik

KTHs team:Patricia Monzó, doktorandDavide Rolando, researcherAlberto Lazarotto, doktorand (PhD tomorrow !!)José Acuña, researcherProf. Björn PalmProf. Folke Björk

An example from USA

Borehole Thermal Energy Storage (BTES)

• Albany, GA• BTES• 306 boreholes• About 64 m deep

DTS at the BTES

DTS

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Monitoring borehole, splice box

First DTS measurement (raw data)

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rature [ºC]

Signal strength

Measured length [m]

Stokes

anti‐Stokes

temperature (°C)

DTRT0

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Depth [m

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Temperature [ºC]

A DTRT has been recentlycarried out in order to get a better insight about the geology

TACK!

Contact:

José Acuña, PhDKTH Royal Institute of Technology, Sweden

Mob: 076 232 00 08Email: josea@kth.se

www.energy.kth.se/energibrunnar