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TRT: how to get the right number - Groenholland

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TRT:howto get the right number
HEcurent9obalclimatedis@$ion
hat
{imulatedenormous
int€rcstin energy
savingiand9reenho!se9as
emisson9.
red!cingtechnologis.Oneof these
lech.oloqie5,.nd
o.e rhatis.apidly
-a
Thermal
response
testing
forborehole
heatexchangers
validation
ofassumptions
byDrHJLWitteofGroenholland
BV
spaiial
5cle!p rohundrcdi
ofmeret.AI ofrhere
theneasuenentasanadditiofalthemal rcsina^(.
gainin9marketinterest
stheqround'sourceh€attempohandspatias.aesneedto beconsidefed ForrhellTthe infinitel.e!oufce i5defineda3
pumpforheat
nqandcoonqhousesand
offcet
duin9thedes9npb.e!s,
gn€dq@und'sourceheat
Witha poperlydes
In,ummary,
lhedsignolthebo€hoe heat'
pumpsystem,
pimaryenelgy
and.arbon
emis5ion5ex(han9er
sysenhinges
onthre pl ncipal
.rsocatedwithspace
heating
and(ooingcanbe
redlced
by30%or
more.
qv VolumenowcnGhtionmedum
Mor@verthepopulaiityof I Whatisrh€energy
loadonlhegiound?
( rculation
these$atems
i! notdletoene€yetriciencyalone. 2 Which
heatexdangeiand
borchole
r
mdium
oensily
Otherchara.te
5ticofthe5e
3ystems,5uch
a5ther
construdion
ischosen?
.
Neat.apa(rycnulaionmediun
JrLk9(
r0burtne$,
lowmalntenance
p.op€rties
costandverylon9
3 Whaiarethethemal
ottheqround? I.. Retom
remperaturc.ifcu
al onhedium 'c
liferpan
areoftensufiic
enrrca5onsinrhenown
ight.
l.
inje.lion
tempeoluec @l.tionmedium .(
Thevenical
bo@ho
€ heanexchaiger(BHE),
used Inefi6tquenion
i5derlved
fromthephy5ica
li
AveEqetempecture(i@lationmedum .C
.C
asa $ehal.source
o.therma5iik offe6ma.y
bli dingpropedes,
buldingus€andlocation,TheIq Farieldlgrcund)lempeEture
advafta9Bfortheheatpumpoveroths media
di!rnal.
Fahnalandyearyloadpofile,aswellas I
Gouodlhermalcondudivty
iuchas9rcundwater
orairTorhermally
activate
the thepeak<ap.chies,
arcneeded.The
canbe
second
paEmetets
a heatex.hanqer,
!s!allycon3isting
ofa
eigineeEd,
baedontherequned
and
slound,
nurnberoihighitrength
PEl00oopsfsertedI
holes
isneeded.
qlrestion
dnlhdto deplh5of50l50m,
Thethnd
willbeverydilli(ultto e5tiilate
pbvides
TheBHE
theinledace
g€ne.al
p.i.ciplesor r
berwenthehear withsufficientaccudcyfrom
Borehole
d ametef
pumpand
theground,
andthatc whercgood
fromavailab
e 9eo109kal
dataalone.Th€
rherma
k Coelli(entotthe.egreir
onT,wrh
design
L needed
arth€functioiing
oftheground- properties
ofthe9ro!ndarerhethemalcapacit,
ogarilhm
ctimeft)
(VC,wheeCi! themal
eneqystoG,
6i w€la5therotalconoftheryn€fr, lheundinurbed
tempeEt(epolil€andtherh€rmal d ftemald fiv5ivity
dependsto
a largee{entonrheBHE.Ihecav€at
is
conductivity.
Wilhrcspe(to thel.ner,it .eed5to be
.apaoryr
thattheene,gyfow
intheground
isreativetslow reasedthalit s a$lmed$at thema. processof
Thisallowslhe
grcurdlo b€usedd5.naccumu
ator heattransportiscond!clivity(a.d
not,forin(ance,
Thi,form!lair validwhen:
ofthemalenelq,butal5o
limitsthe
inrtantaneou, matsrnnspon
dueloco.vectionoradvedion)
(apaci9(duetothedalbuild!parou.dthehear
u5ually,
b!t(€ftalnly
nora way5,thii
wil betheca5e.
erchangerjand
mayinoeare
boreho
e ntedercnce Final
themiualrhermalconducr
v ty
restablshing
(d!etothermalboild'lp
inthenorehtelfover
ofa sp<ilicdepthpofilesquitedifficu
taerhe
Therherma
frcm
condu.rivitycan
beenimat€d
peiodt. r al5omean3lhatthehear va ationwithinvinually
lo.gertime
similar3oil/sedimenvrcck
eKhanqscannot
besized
oncapac
tya one.
typesisverylarg€
duetorheeffectr
ofwaier
-G.,6
r \\
ground
porespacinq
Let!fi6t like a c ose.lookathowthe
content,
andpacklnq
de.sty,fEctlre
queuion
parcrns
$o€ functions
a.dwhanhedesiqn
k.
andotherphenomena
influen(inq
heat
p6Gmeterlkl
conduction.
unar€ly,
U.aoft
a 96lo9icatomation,
WheEthe
equalirherlopeof
a
HOWTHEGROUNDSTOREWORKS
evenatthedefined
levelofa
typeocalty,
isnotvery nearreqression
oftempef
dlurewilhlogarthm.
Thetheimd
oadisarcsuhofthe
heatgaineand homogeneouseven
inthebeitofc rcumnances. time.When
/ ha5beenenlmated,
thebo.ehole
heatlo$esolrh€
genecltherewll bea
building.l.
rciistance(Rb)can
becakllat€d
usingthellne
denandforheatinthewint€rand
d demand
forcoo THERMAT
RESPONSETEST
inslmme(Duingthewinterth€
grcufdwlll.oo
(TFT)is
Thelhermalrcspofsetest
based
onthe
Inl995,thetwofirstrea
i s tu r€spon5etens
premi5elhat
downasheatisextEcred,whilein
therummer
rhe
th€temp€Gru.e
Esponse
ofa mare.ial, (typeI re(t weredeveloped
intheU5(Austin,
I998
grolndt€mpeGture
(torcibly
incrcase5d
heati5reje.led
whena thermaenerqyflux
heatinq
o,
andSwede.
I996).rhesetenelse
lEkldi&Gehlin,
ntoth€ground,
Depefding
onthebalance
between coolngrhefiateia ala ce.tainocation)isapp
ed
dn*t h€atn9ofafluldpumped
throughihe
heaun9
and.ooing,thereisnotonlya5easonal,
but i5proportional
rorherhermal
cond!ctvityofthe
bo€hoe heatexdanqffai
a the.maforcing.
alsoa temp€larurc
t€ndov€rtheyeaB,
mateial.fti,reration
L expretsed
byFourie*lawof Withlhismehodsomeploblemswe.eforcseen,
Thetemperatu.es
o(culnn9
intheground
arc
powerl!r
ruchasthatofnainiainii9
a con5tant
lmportantforfte
function
n9ofthesynem,
borhin
andcon-vection
eff€<E
duetowater
heatn9ln
thesho(a.dth€lonqtem,arthepedomancand
theborehole.A
usesheating,the
so,asthere$
capacityoithe
heatpumpd€p€nd5
toa laqeextent
exp! mentcondition5
arcobviourly
notconparabr€
onthe9round
tempeGturc5,
i, :Thedralconductivtylwm()
toa h€at-pump
sFtemope€tingn heatextd(on
Gouice)
Forevery
K ntemperaturc
change
thecoellicent VI :T€mperaueg6di€nt(Kl
(vanGeldereral
ofrheperfoman.e
oftheheatpumpwill.hangeby
Inl99ZGrcenholhnd
1999.
about3%.lheEfore,
itisprcferable
tochoosethe
Kelvin's
p@senred
Using
in€source,
a merhodcanbe
wrreetal2002)
thefid tesrGpabeof
(typelltest).This
snalle5t
storcthatdelver'
devised
llowenincost)9rcund
to measure
thecondu.t
onofamate.alby bothheating
and.ooling
ten
pobe{va.Haneqhem,l98l),
withinrheaccepted
tenpe.at!re
bandwidth
dudng a needle
machine
whercthe
useda reveuibleheatpump
togenerate
iheopeBtional
po@r,a.d employ€d
lifespan
ofthesynem.ln
thiswat
needle
isinsened
ina marerialand
heated.Tne
theheating
orcoolinq
.n
performance
theloig iem, aveGgedesign
(usingathree-wayva
oflhe
temperaturechanqeoithe
needecii bemear(ed aclivecontro
syn€m
vernd
heatpumpinltalationi5wa@nt€d.
pump)tomainta
anduredtocaclrlate
thethermal
conductivlty
ofthe IfeqLrency
contrcled
n rhe
Temperatul€,
intheBHE
varyara rcsuh
ofheatmateal Tnismethod
it usedinth€laboElory
but
rcqui€dene.gyfluxtoa
highp.ecision.Al3o
1r
pumpcycllng
andpo$ibe diu.nal
loading
alsoi.a9(hu6lsrldie5rodeteh necondu.tivity includedfull
telemetryto
both(ontrcland
monro.
(limeframe
ofm nutesto
hou6;rpat
alscaleof
centimet€ts
todecimet€u).
Onthis5cale,
rhe
ln 1983,
Mogeson
wa5thefi6troproposesuch
a
Io benerrhequanriteffed5
orEoundwate,
capacityotihe
borehole
heatexchange.
it impoft
ant, t€5tforthein'situmeasulement
ofg.ound
th€mal
flow'andotherpb.esFsaffecting
h€altdnspo^(rirnescaleoldayrconductivity
asa rcsuhoithe5€asona
loading
a borehole
heatexchanq€.
using
n this the9round,lh
5restwa5s!bseque.tly
er€nded
(boteho
to months;spatialscalesofnellet
andasa resut oi
casethe5pat
inroa mlhi puseten{typell ten)6 f9 a i€quei..
aldim€ns
onofrheheedle
e
$eyeadybalance
p!lsesatseveralenergy
{iime(alebeinqtensoty€a6j hearex.hang€r)cannot
beiqnored
andi5reflectedln olhealinq
andcoolinq
I o-e;-r4,firl,) ra ,,Dt_,.
30 GeoDriltino
Intematloial
April2009
eveh(Wine& vanGeld€r,2006).Obviouily,
such
ten results
cannolbeanalysed
usingrh€slmpe
ineso!rcemodebutar€evalatedusinq
nve6e.umei.a modeln9with parameter
l0
Innrientborehole
28
24
h the.la$icaltypertest,thetenperature
o
GspoNeofrheq@u.dan bepan[ oned,asseen
in fgure I Thefl6tpan oftheten reflect5
the
nansent borehoe rcsponseand
!notused.The
P.v
juirpfrcm the undnurbedtemperalureto
re5irtan(e
Borehole
the 5ta(
in(GaieBa
olthesreadyiatetemp€Gturc
Ero
measure
of the boEholeihermalrc!iiance Thi5
P-.
a readyimples,1|om
thata
the lnesourceiorm!la,
't4
vefygoodmenufemenrof rhe ufdi5tubedgroufd
rempe.atueismpoftant.Thefinalpan,rhesready
tarfeldlemperature
nale remp€6rurcin(rca5€,
acluallymea5ures
l2
qroundthermalconductivity.
'10
A numberotmporianrissues.re:
30
20
I selectnq a healfluxthatislargeenoughto
good
Time(hour)
suffcentlyforc theg@undlachiev€
5i9naro no serario)dndalsoal ow 5uffcient
measuremenr
PRII{CIPAI.
with owerheatcondudivry leadingto an
rime(norioorapidthermal
ASSUMPTIONS
OFTHE
saruEtion).
Typ(al raiesare30'l00Wm.
INFINITE
LINESOURCETEST
u . d e r c r t i m aoriet h e f o r m aotn j p e cf c . o n o , : 1 . ' ,
lobtain nqa sufic entlyaccurate
soi-tempeGlure IThebor€hole
heat
exchanger
lested.an
be
F o rt h e a r g e ' da m e t e r € n e f glyepsc o m p . : : : :
con5ider€d
ar an in,i.ite linesource
c o n < r ew
r ei t ha h , q hh e a t c a p a cai tnydd e n r : , " .
I Ensuriiqa good.quaityborehol€heat€r.hange, Thefi6tassumptiof
themal5to6geefle(.annot ben€gecrec to belestedis ifth€ borchoe
generalthBwillaga'n
l€adto anovercsr
heater(hanger<anbe(onsid€Fdto co.srhur€a
o::.:
Moreover
dependin9
on wherherana..urat€as
lnesource,n qenera,aborehol€
heatexchanqer
t h e r m ac o n d u . t v r tFy o f t h e 5ge
p05sibe menurement
of so thermalcondud vityor hada engthof 80 l50manda diameterof
0,l5-0.20m anayti(a sout ois havebeendele opedlBar::, "
yc ose
a chara.rerisation
iBta ation
Thesedimensions
ar,2008).
ofa 5pecificborehole
canbetlken asreasonab
a5installed
i5req!ned,thefolowingmayapply:
toan intinte rnesourceas
a i i o no t r h €m l n i m u -- : : :
theedgeeffecBat thetop
5 of a Li o a . t u a ci a l c u
parameie6to
I Seledi.qte5r
esembeactual
andbottomofrhehearexchangercan
be ig.ored.
D , L , b e t w e e n r h € d ' a m e r e r ( D ) a n dLl e: n-g-r. h
p anl opeGrionldifierentextadon/lnjecuon
: or€c
Also,theeflecBofih€ s zeofthe borehole
andpipe
borehoeheaterhan9erhasbeenprop
a(ura.y.
eves,cy. n9 etc)or in.rea3e
aranqemenr
wilhinlhem canbeiqnoredafterthe
5 e e m s r e a s o n a b e r o a $ ! m e , h o w e v e r ,-t h a i a :
lDes 9n borehoe aid €rps mentpa,amete6for
fi6t iew hou6oftheien havepdsed,andthe bore
<0 005isacceptable
Foia loom-deep8HEs. :
lowenbor€hoe resisiance
or besrresemblance hol€'vall(anberakenarrhesour.€ofthe heatllux. diam€r€rof0.2m,lhe
A t!D1Lisabout0.002.
(an be
to e.9ineeredborehole
d6 9n.
Ho'leverorheftypesolheat€xchan9e6
b o r e h o l e e x c h a n g ehrawvi e
l a D / L o I a b o u: t: :r
preiabicatedloundaton p ler
tened.Erample5are
Ai energypll€wi haveaD/L>0.0125.
prevols y erp a ned, or n 5iiu(onnructediouidationpi-4s.The
Thetens,in the n<amarions
fnn da$
havebeenii useforovera decadenow with
lThe conductivityof the soili5hot.opic
usualy conrn oisquare,con.rete.on5tru.t
onsin
grear5u.ce$.overl0rendpparatusaenowin
This5,e5pecially
n 5edmentary(!nconsold:r.:
useworldwderoutinelyand
de iverimpoftant
typesof96 09, hadlyevertheca5e.Th€fo.r:::informationtodesigne6on5oi
lhermal
.omallycoB nsof a sequen.eofd fteent
conductivlty,
soi-hearcapacity'
s!b5!dace
matefalslsands,clay5,9rave
s,pearetc)with
profiesandgeothemalhearflux d
temperarure
variousthi.knerse5,
whereeach
maieia hasr! :,'_
p.operti€s.
wellasborehole
hedr'erchanqef
themal resistan(e.
Forinstanc€,
d!ero pickln9,the,?-:,
p.eierence,similirrowh.ris
ic-':
Howev€rastheTRTevolvesfromatoo
usedby
bea diiectional
5pe(iaistswitha fundamental
undeEtanding
olrhe
wirhhyd6u (conductvity.Moreover,
ofteno. .
processes
partotthecompetevedca p@flewi bevrai.invovedto more3tandard
meaturement
methodoogy,the standard
evalario. m€thodsfa
ari :
saturated.
other siruauons
oftenencountered
shoft.Mainly,
the b65icasumption5tharrhetest
ofhardrc.k,wearf:..:
9eoogi.a protilecon5i5ling
make5,
andthe limnarions
on confgrarioni where
rockorconsol
datedmateialtwith anovelbu,.:therestmaybeused,are
not slffc endyaialysed
or
of ooseorsedime.tarymater
als,oftenwithea:.p pd de
co.s deredin the standard
evaluaton method.
whkh a numberofpolyethylene
bear n9 aye6or seepage.
l lomogeneoG
9s oq ::
lntegrated
durin9mdnufadurln9
These.ondd6s s p@rlesarenormayrhe excepton.
f of theTqTdndmeasurementoithethema
IIMITATIONS
eitheraugeEd
orexcavaredloundation
elements
of
TheTRT
i5a nea3u€mentpro.ee5,which,
ikeany
la|gerdiamer€6.A
numbsofpolyethyenep pe5
condlciivity,thevaiationisnotagrcatprcb€tr'
preckion
measu.ementi
hd5a certainaccuracya.d
ar€fxedrothe rcbarbeforerhe
concrete5poured
rhespecficthermacoidu.t vityofthe profie !
thatcanb€natistcallydefined
Thedefinition
of
i n . l n b o t h c a s e s , r h e l € n g r h o f r h ei p
mi il teei d
5 a n d needed.
Forthedes9n ofa bofehokheat
seisoreror sfaniystraightfoMadandstateof
@ m m o nl e n g r hrsa f q eb e t w e eIn0 . 2 5 m . h t h e . a s e exchanqer
therefofe,
whenrhetesrheateKhang€,
the'a.ttesteq!ipmentachieves
theoretical
accu.acy otthe injnu piles,oftenthediameterisquite
arge
5 instaledto a s m hr depthastheprod!.t o.
lly eldv.lue5otcond!.r v{J
ollhesoilthemal(onductivitymeasuEmentof
a5v/e| (1.3m).IhercIore,
rher 9
bo.ehol€,theTRIw
linesour.€
betterthanl0%.Howevef,
the.€arenany p.oce$es b€con5idered
equivalent
toan inUnire
thatcanbeusedd recdyin the designsoftwac rl
affecting
besdes
theaccuacyof $e measurement
andthe effe(tsat the top a.d bottomoflhe
th s G notthecaseca.eshoud betaken.
lf,Ior nnaice,thedeeps pa^oflhe prof e 5
e emeit,atwellasthe largedameterandlarge
Thedscu$iofoi alliour.8 oi ercr in aTFTis
if terfal h€.r capacity,cdnnot
beiqf ored,
composed
oia layerofmarkedly
diliercnt
(onducti!irya.d rhef .al borchoe heatexchan_oa
paper,burrh€validityol
beyondthe5copeotthii
one(an ina9inetharrheaddedeffecroi
evena perfed(erortrc€)TRTexper
mentdepends downwardhear$anspo(atrh€endofa relarively
depthisl€nglh€ned
5i9nficantyGpe€ renrkr ons
o n a n u m b e r o f f u n d a m eanBt a! f i p t o n s t h a t
sho( hearexcha.qerwllladd
a v rtua engthto the
on sire)thi5mayre5urinan undendesi9n
a5ihe
&e madeconcemnglhe prc(es!ofheattnnspoft
borehoe heatex.hanger
andtherefo.eeadtoan
s p e cf i cc o n d u c ttl yv v au eu s e dw i b e t o o h q h
ithesea$umptionrdo nothold,thelestresulrs
overertimare
of theio I thefma .ondudivity.0n the
Conve6ely,
fa ten is psfomed on a rhon
(o!:,
maybe ina.curate,
fof instance,
a peatyorclayey
bias€dor evencompleiely
otherhand,neartheslda(ea reativelylaqefpart
borchole{wirh,
layeforwsaturared
t
ofthe heatexchanqsmaybe in unsatuared
soil
soilp@fileon rop),and
onthe
"Depending
balance
between
heatingandcooling,
thereis notonlya
seasonal,
but alsoa
temperature
trendover
years
Ine
t
subsequentlyrhedepth
ofrheheatexchanger
is
incleased,an
overiesiqn
hayRsult
Foranlihomoqeneous
soiprclile,
itispo$ibleto
derve.ondudiv
tyvalues
fo.indlviduallay€u
thro!9haddtionaltemperat!G
measuremenB
at
thesedepths.Thesecan
inditrerent
beobtained
eayt tuchasfiberoptictemperature
measuleme.G
inrheheat.exchangerpipe!.
Nowever,
a thoughit i5
po$lbleto m€a5ure
thedlffere.t
tempeEtule
rcsponsesi
ir i, u5ually
nota:easyro
mea5urethe
E t.t
(andtherefore
pow{ Eiet
temperai!lediffercn.er
attho5edifferentdepths.lt istherefore
fanly
tt6ighdokadlo measurc
beMeen
dilfeences
ho zons,
bulnotroealytoacclratelyquantify
lPoce$otheatt6nsp.nh by.ondlction
only
Tlisisakeyassumption
asthelinesouKetheory
whkh.lowsu romea5urc
condudvity
withthe
0
20
40
60
80
100
(hou|')
TFT,
aswellas
theactuarcsuhobtained,
depends
Data
indoded
p|oce$ej
onit.N€xitoconduct
on,rheheat
transport
tharoccur
aredueto mass
nansport
orradiation. Fiquk 2:.onstdn y af .ond!.rivity eninate uting thelineso! ke appbo.h in ondpe ne ht with ohd||ithout
FadiationoccL6
atthe3udaceand
canaddeneqy
totheryst€m
dueroin.oming
radiarion
fiomlhe
5un,whileene€yis
beinglostdu ngrhenighrdue
Apantromsubs!rface
flow,olhe.possibilitiej Atlhatmomentthe
dal6trcmthetestc.nnot
b€
tolong'waveEdiauon
Onlheumescaeofthe
ruchasrainwat€r
runofi(on
o.inan
u3ed
hil5ide5
rocalcu
aterheborehole
resistanc€
or
experment,theetrect5oiGdlation
on norftaly
nadequately
backfi
ledborehole),
orev€npumping conducri!ityand
a ce(ainamouitoftirnehasto
pasrbeiore
frcma wellofeKavat
onordriiingdo*torh€ten
accurate
ca. beobtained.
esrimat€s
(cuB thrc!9h
Ma$t.anrpon
inrhe9round
rile,needlo beconside€d.
Orhereff*rs rhat<a.occu.arc:lnfih.aronof
goundwaler
flowWe.andistinguCh
lr isnoreasyroquanrifyrheamounrof
grcundwatefGinwater
thouqhthetopoftheboEhole,
of a
9rc!ndwaler
porou!m€dia, flowlomthetenEsult,bulGroenholland
flowinpo.ourorfnctued
media.ln
hd !5ed siphon
etf€<t
betw€en
differcnt
laye6.
Bothmay
allh€atexchangeE
inanarea
w ll experience
morc puls€
r€5ulr
tenstoadiveat
slcha quantification
ot
ininfinite
conductivity
andze.oborehole
groundwaterflow,
or es!the5ame
andthegro!nd grouidwaterfl
owetrecs.
VeryhighIlowlar€s
will
r€eistance,
andaGcaused
by mpropersealing
of
waterflowisfanlyconna.t
inthelayerwhe.e
t
18!hinaninffnite.onductivity
asthet€hperatue th€boEhoe.A50,th€boehoe maybeunrtableo'
&.uu {alihoughmark€ddifierences
betweenlayere Bpons€oftheboreholeheatexchangeri5connanr
collapre
llingord€r€io6tion
dueto imprcp€r
backfi
awayimmediately).
hlrheart6neponed
LateEl
lloworadvecrion,
occuAa5
Anolher
effect
ofqrcundwar€r
€sped.lly
inthe
ThiiwilldGmatGllyaffecrthe
rceul$a5the
Eoundwater
pre$ure
qEde.t.Theamounr
a resultoid
ofwarer borehole,
heatexchanqerpipet
naybeconvedioi
o(udng duerothe
maybecome
exposed
and
thalcanflowthrough
azoned€pend5
onthe
atefaltenperatwe
Even
nl(o'convection actveborehole
length
changes.A
so,h 9h9Gdlent,
prc$!.edifference
andhyd.aulic
conductivit,
ce15intheboehoe porespa.eswillEduce
.esninceborcholeswilly
eldpoortestl€suhras
exPre5s€d
i^ Ddcy3law:
borehole
theterttimein(ea3e9and
esinan.eand,
ona laqerrolegound
a lalgetemperaruE
dift€€nceis
needed
heatfluxrothe
rogeneEtea
Obviou4y,
l€ttin9theborehole
re$and
9round.
(urebetweef
nh
Q: Darcyvelocity
thedil ingwotuandinitalation
K: Hydraul
c .onductivity m/s
oflheloopand
thena.toftheexpe.iment
is
vP: PresluEgGdient
neacrualvelociiyand
leng$ofpathtGvelled
alsod€pend
ontheporosity,
TheOarcyqrcundwater
llie €neqylluxk con{anr
fiowdivided
givesrisetotheeffective
bytheporclity
Although
il
thisisanassumption
oftheten method,
groundwaref
f o* Forfra.tuedmedia,
rhe
s moEchaEdef
isricottheteltequipmentand
not
qroundwaterflovris
cku arionof
muchmore
ofthegound.Nevedhel€15,
itisaveryimponani
(omplex.
groundwater
Fora large
volume
theavedge
a$umptionofrhe
linesouice
merhod.Th€
rypeI
flowinf,aduGd
medhGn becakuiated
lsingan
Gnsrhatdepend
5ol€ly
onelectncalhe.rer
eqlivale porosityte.m.
Forabo€holeheat
el€mencand
haveno.ctive<ontrcloverrheeneqy
exchanger
howevei
it i5mLrch
y fromthi5pbblen,
mor€€l€vanr
fit
the.m6conductivitywi
hlgherIna heatin9 inputs!tre.espe.la
appear
'h tr'afEctur€
powefwil
ornot,whchlsa malterofa
experim€nt
thls€ffe.tii morepronounced
Fluctuationr
in9id orgenentor
a5ih€
probabil
tyrhatd€p€ndson
thefracturc
densityand change!
invi(osityanddensityworkwith
change$epowerinpu
intotheborehole
the
heat
(onvetionforce,
spatial
infte soilvolume.
dB$bution
whileina cooling
epeimentthe exdanger
andaffect
thesechanqe5
rh€testresuks.
(sudden
fte efi(t of goundwaterflowonaInI canbe
highervGcoiity
atlowsrempehtues
adsasa
c.n bestepped
change
in9 d powe,)o,
madevisible
bycalc!laling
theconnan.y
ofthe
bnkeonconvection.'Tlerefore,thedilferences
mo€gEdualand6ayexhibitcydi<behav
ouL
€se$ onsolution
a5moredata
sadded(figurc
2). foundinborchole
rc5istance
andconductivlty
Examplesof
cusesofchanq€s
ine edft al
phase
lfthesoutionintheheating
powercaf
ofthe
between
h€arinjection
bechan9es
inambienttemp€|ature
andheatextraction
(affect
experm€ntdoe5
notco.lergeto a stableenihat-. expeme.BontheFmeboreholeareprobablydue
nggeneGtof
f ightcyclk
outpuo,day
ofq.ound
themalcondudivity,
butcontinles
to
dema.do.theqd,o.lower
demand
o. thegid
5e,thi5
i5ac earindi<aiio.
ofgroundwaterllow
lBorcholercsistance
h,afteraninilialtransient
Themainwayold€alin9
whhnon<onscnr
powerinputisthrclgh
Theexp
analion
fofths isthattheamount
of
theu5eofinveuenum€ca
heattGnderedtothewaterd€pend
onthe
Theborehole
modelling
aff€cts
$e ten ina nlmberolway'
ordeconvolution
t*hniques.
parameteiis€d
tempeGtlR
diffeGn(e
belwenthegrclndwarer Theborehole
isnomally
asa
andthefluidintheboGhole
heatexdanger
and
resttancetem (borehole
esistance).
blt whenthe
coNctustoNs
thkditfelence
increases
heats
provideinvaluable
asthefluid
up
frcntofa temperatuG
tieldpropagates
through
the TnTrdeveloped
inthe 199os,
duingtheexp€ment,soappdentconductivity borcho
e{whkhhapp€ns
ateachchang€
inheat
infomationiof the de5i9nof 9rou.d 3oulce,
prc9re$ive
y higher
becomes
flux)thercsistance
5notneady-state
butt.ansient. clo5ed.oop,
heat'pumpsystems.
Fromrhedill n9 t
"Testsarenowbeing
perfolmed
routinely
worldwide
and
becoming
anintegral
partof thegroundsource
heat-pump
designer!
toolkit"
32 C&0illin9 InterMtional
April2OO9
oftherdalboEho
eandtheinstalation
oftheloop,
pGcrical
intoffiation
sucha!d lllngcondiiont
qrouodwater
soilnlaignphyand
lelelcanbe
Inrhere$ thesubsurfa.e
emp€Gtuepofile
andborehole
rcsistance
soilthernalconductivity
aremeasurcd
whieaneimateotthsmalapacity
thingshappen.
fied wheedanyun€xpected
Inaddnion
tothefundamental
assumption!,
orhertoures oferor al5oneedto beconsider€d.
Ina recentinvenrorv.
identifieddt
Grce.holland
"Thevalidityofthetest
onwhether
depends
made
theassumptions
actuallyhold"
Mode.n
rerts,
likethemulti-pul5e
test,developed
anduse
andpat€nted
byGroenholland,
aleveBatile
accurare
ten prccedures
rhatyi€ldderaild.
poc$
add(onalinfomafonontheheat-tGntfer
goundwater
inthe9round,
adv<tion
least11differcntsourcerof
ero.,fromsensol
includin9
erorandheat-tEnsferfl
Lrid
chaEctennics
to
tyofthetestd€pend
on
erc6 anderclsinthemethodology
However,
thevalid
natistical
yhold.
whether
thea$umptiof
s madeact!al
m€nt,
Iti5therefoGimportanttote5ttheseasslmptions
n p.actcehowever,
ina wel pla.n€dexpe
andcalibEted
o. a rcurnebasisa5thetesti5notperfomedin
andusingpope/lyprcpared
conrtoll€dlabocrcrycondition!,butin rnu i. the
equipmen!ate5tLilurcofa le5ti5very.areindeed
eto'fr€ak
andalmosta
waysattiburab
evensl|\.
andpumping
nearthera
u.forer€nexcavation
site lnu{ally h€aly6insor.in very.a.ecaiei,
innrumentfailule-Ofren,
byueingaoaltemative
evaloation
method,posibtincombination
with
extendingth€tentime,
uleable
EsulBcan
nil b€
pedofmed
Te5ts
arcnowbeingroutinely
panofrhe
anintegral
woddwideand
becoming
gound{ource
heal-pump
d$iqner's
tookit.
we hop€that,withthit paper,wehavemadeclear
rhatwhibTnTsarcbecomiog
a moreoutinetype
of masurenedr,thequalitya6du3ablllry
of the
te(depend5on
a goodunde6tandh9
and
evaluatlon
oltheten method,
assumptions
and
Without
lhere!ullra.e
suchunder5tanding,
justanumber
a wrcngnumber
and,tooofren,
REFESEI{CEsI
Aottih,WA,|9.Develapneh!afonln-SnusyttenfotMeasutingGrcundThenalPtupettks.llttthetis,AkhhanostoteUnivetsity,15.164pp.
in rhemolResponse
r4ts.
Bondat,fv,MontdaA,Ganzile.tL hidrc,tM Petez,
J,Fthdnde.E,FqndndudeCAdoba,
JF,2008.5eothqnolVettlcalEffpcts
e Urchueguio,
Enqiheuing,Stonford
Cdlifanh.
Ihng-fhndwatushap
on6eothqnolReteNoi
Unive\iry,stunfod,
eonsubtunneHeotStongeih fhearyand
of dElntemotlanalConfeftn
Moqson,e 1983.
FluidtoDu.two HeotiansfetinDuct'ystenHedt'tahg&tuoceedings
Pradice.sw?dish
C@nilkt EujhingR6@t6.
t8, pp.
ofwageningen,
VonHonegheh,
tA,t%1.Ed niet otionone
noaknetho.L(wnte1eletulinq,
wottuEcaprcitet.6tocMeetttand).Ihesit,lkiveuity
lot ThetnolRetponalests,Motte/tth6k l9& 198E,
LukoUniv5itt ofle.hnoloy Sweden.
Ekl6tCordGehlin,5,
1996fED- Anobileequipnent
desUntetgrunds
dutchwatne.n'ug. tN:Hiniget,
vanGeldet,
AandWenn?|es,
BGA,
199.ln1,itu
Messungu
detkemit heLbenschaften
N, Wifte,Hu.ltilho, S,Shijde6,
I (Ed):
oPEfSeninatEtdgekoppelte
Wilmepunpen
zun helrenundKlinotisiercn
vonsebatden:109pp,
tonsodiontvolume,08,No,L
Wtte,HJLlan Geldet,
N ondSpltlet,
lD,2@2,lnsluneasutenent
ofEoundthenolcondudivir/:The,uxh pecpectiv.ASHRAE
quanttfying
gaundwotet
eflecttonheol
andcaolingpohes:
Witte,HJLand
von6eldet,
N,2M,Geothqnol rctponse
tettsuing @nhled nukiAa||a leveiheoting
heotxhongeLE 6tork 2M.
xonspon
oaundo barehole
34GeoDllinsInreharional
Apr 200e
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