ecovat thermal analysis 0. ob
TRANSCRIPT
Assessmen
0. Ob
Thethermodyn
Spe
Q2:depend on
Q3:argued scielonger hold
As expected tassessmenstage.
1. Bri
Seahot/cold wcool buildin
Hownumber of plants have2006 till 20Yet, large sbetween 1storage woduring sumSTES can bsummer timof electricaheat pump
In gand chemsubstancesare therefothermal coexpansion
ntreportco
bjectives
e objective namic quest
ecifically:
The claime the density
The claimeentifically (ads.
indicated into be carriet, due to th
iefstate‐
sonal thermweather to bngs.
wever, the large solar e been insta012. In Densolar therm10% and 25ould be necmmertime dube seen as me and exceal energy insps or under c
general, theical mechas that experore density onductivity coefficient,
orrespondin
to be covetions arisen
ed 93% effiy of the insu
ed stratificaalso on long
n UPC offeed out by he strong re
of‐the‐ar
mal energy sbe used in th
number of thermal syalled worldwmark, only
mal systems 5%. To increcessary. Thue to a largea solution ess of heat stead of solcertain circu
ermal energnisms. Senrience a chaand specifand diffustability, re
ngtoSUBU
ECOVAT
ered by thduring the
iciency needulation.
ation of theger time sca
er, this repothe use of
estriction in
rtinseaso
storage (STEhe next sea
installationstems (> 50wide in thein 2013 9 pwithout seease the sois is especie solar fieldto bridge demand duar thermal umstances d
y storage cnsible heat ange in intefic heat. Othsivity, vapoesistance to
UPC2014V0
TTherma
is report isKIC Review
ds to be ar
e water layales, like mo
ort correspf simplifiedtime that n
onalther
ES) technoloson. The st
ns with seas00 m2) is rise period 198plants have asonal storolar fractionally true wd capacity tothe gap beuring the winenergy and direct electr
an be classstorage isrnal energyher importaour pressu thermal cy
0.1ENGsub
alAnalysi
s to give a Committee
rgued bette
yers with dionths); if no
onds to thd models annot allows t
rmalener
ogy enablestored energ
sonal storagsing expone85‐2012; obeen instalrage can onn of these swhen it como cover heatetween the nter. Ecovatits conversrical heating
ified by stos based ony. The main ant propertre, compatcling, and c
bcontracting
is
detailed se on the Pro
r with calcu
ifferent temot the funct
e proposednd bibliogrto deal with
rgystora
the producgy can then
ge is still limentially, e.g.f which 138led with a tly produce systems, th
mes to avoidting demanexcess of t storage syion to thermg.
orage mechan the chanproperties ties are: optibility amoost.
1
gfromVITO
scientific anoject 067‐EC
ulations. Th
mperatures tioning of th
d Phase 1 oaphic/knowh CFD simul
age
ction of heabe recovere
mited [GUA1 244 large s8 in the lasttotal area oa limited se use of lad overheatid in winter.heat produ
ystem introdmal energy
anism in sege of temof the mateerational teong materi
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nswer to thCOVAT.
his will sure
needs to bhe system n
of the worwledge baseations at th
t/cool durined to heat o
13] while thsolar thermt period sincof 81,000 molar fractioarge seasoning problem In this sensuction durinduces the usby the use o
nsible, latenperatures oerial selecteemperatureials, therm
he
ely
be no
rk, ed his
ng or
he al ce 2. n, al ms se, ng se of
nt of ed es, al
Latetransition) usually use(PCM). Latelower thanthe use of phase or thdischarge.
Chesolar‐drivefuels that cuse of solaand recycliwaste and
All based on sthe Ecovat
Am(UTES) comones. Exten
BTEor horizontand water space betwgrouting mits high iniFurthermolong time r
In Awell to wgroundwatextracted creversed dquality is nthe temperbe installed
1.1
Wat(comparedAmong theexpects to
Wat
ent heat stor heat of ed. The subent phase cn in equivalethese matehe degree o
emical heat n thermochcan be storr energy foing of wastof secondar
these mechsensible (liqstorage tan
ong sensiblmprising aqunsive review
ES technologtal tubes. This used as thween the pmaterial in otial cost dure, it has arequired bef
ATES technoork [PIN11ter is extraccold water uring wintenecessary forature of thd to provide
Large wat
ter is consi with other e STES usinguse water a
ter tank/pit
torage is bavaporizatio
bstances suhange heat ent sensibleerials difficuof degradat
storage is ahemical proed and tranr processingte materialsry raw mate
hanisms canuid or solidnks.
le heat stouifer technows of these t
gy uses grouhe insertedhe transfer pipes and trder to enhue to the exlso to be cofore achievi
ology wells ,XU14]. Duted from atabsorbs theer. The heator them to whe groundwae additional
ter tanks an
dered one sensible heg water as mas storage m
t storages a
ased on laton (liquid–vitable for s is high, so te heat units.ult such as tion they ma
a wide concocesses are nsported, sug energy‐ints: use of soerials.
n be used, d or a comb
rages, wateology (ATEStechnologie
und/soil as T tubes servfluid. To prthe borehohance heat txpense of bonsidered ting a quasi‐s
are used touring summt least one ce heat and t capacity owork propeater is not sheat.
nd pit‐stor
of the besteat storage media can bemedium as w
are artificia
tent heat ovapour transsolid‐liquid the size and. However, he low theray suffer aft
cept that caclassified auch as hydrtensive, higolar energy
in principlebination of b
er tanks, w) and borehes can be fo
TES. The gre as heat exovide good ole wall is transfer. Onborehole hethe low thesteady state
o carry watemer when ccold well. Inis injected of aquifers ierly [SCH03]sufficient en
rages
t media formedia) ande found largwell.
l structures
of phase chsition). Thetransition ad cost of thethere are a rmal conduter a certai
an be underas: i) converrogen; ii) prgh temperatfor detoxif
e, in STES, both) heat s
water pits ahole thermaund in [NOV
round is excxchangers, thermal cousually fillene of the meat exchangrmal capace (about 3‐4
er to/from tcold water n the procesin separates around 30]. It should nough to he
r energy sto, in general,ge water sto
s usually ma
hange: heate solid–liquiare called Pe TES devicenumber of ctivity of mn number o
rstood in difrsion of solrocessing ofture materiafication and
but the mostorage, as
and undergral storage (BV10, PIN11,
cavated andthe free sointact with ted with higain drawbagers and coity, around 4 years) [SCH
the aquifer.is needed
ss of coolinge warm wel0‐40 kWh/mbe pointed eat a buildin
orage due t, its high voorage tanks
ade of stain
1
t of fusion d transitionPhase Chanes would, inf issues thatmost of PCMof periods o
fferent wayar energy if chemical cals and iii) dd recycling o
ost used onselected at
round therBTES) are thXU14].
d drilled to iil is the storthe surroungh thermal cks of this tmplex exca15‐30 kWhH03].
. At least it d for cooling down the l nearby. Thm³ and acceout that in
ng so a heat
to its high olumetric enand pit sto
nless steel o
14/12/2014
(solid–liqun is the monge Materia principle, bt would makMs in the solof charge an
ys. In [RIC10nto chemiccommoditiedetoxificatioof hazardou
nes are thos this stage
mal storagehe most use
nsert verticrage mediunding soil, thconductivittechnology avation worh/m³ and th
requires onng buildingbuilding, thhis process eptable waten some caset pump migh
specific henergy densitrages. Ecova
or reinforce
id st als be ke id nd
0], cal es: on us
se in
es ed
cal m he ty is rk. he
ne gs, he is er es, ht
at ty. at
ed
concrete suvolume is both mater
Theexcavationsummaries[NOV10] ansimilar to aexchangers
Theeconomic aincreases whigher the
In gand the tothermal enOn the othsurface but
Regcostly onesthe costs o
1.2
Thedifference increases tcooling sysexergetic ebeen studiCON04, HAfactors assmixing proambient ththermal br
Usuprofiles unmeasurempossible imparametersthe literatu
Aman equivalemixing and
urrounded bfilled with rials.
ese tanks as. Top ands of the diffend in Pavlova mantle hes and not by
e constructioaspects. Fowith the sizthermal eff
general, gravop can be unergy than aher hand, wt results mo
garding the s are those f those syst
Thermal s
ermal stratifin density, the thermastems withefficiency ofied intensivAL10]. Howesociated witoduced by through the idges along
ually, the stnder differeents of the mprovemens to quantifure.
ong the diffent loss of d conductio
by a thick insome filler
are built und lateral werent projecv & Olesen[at exchangey direct inje
on of such r instance, e of the deficiency.
vel‐pit storaused part oa water tanwater tank ore expensiv
cost of theinvolving wtems tend to
stratificatio
fication, theis one thel efficiencyh heat storf the TES [Rvely and difever, stratifth the loss he inlet strtank envethe tank w
tratification ent thermalevel of temts in the ofy the degr
ferent studicapacity (on during th
nsulation. Amaterial (u
ndergroundwalls have cts involving[PAV11]. Ecoer heated taction of hot
large strucconsidering
evice, the la
ages reduceof the residk design (dutechnology
ve due to th
se systems,water tanks o decrease
on
e natural sepe most desiy of systemage) but aROS01]. Thfferent metfication is chof stratificareams durinelope; the halls; among
of a therml, fluid dynmperature sptimisationee of therm
es can be cr equivalenhe course o
A variation ousually rock
(pits) or cto be insug these largovat tanks aank, as the t water.
tures must g that the rarger the vo
e the cost odential areaue to the loy does not he tank cons
, it was shoand water as the size o
paration of irable prop where thelso reducehe researchthods for itharacterisedation in a tng the load heat condugst other cau
mal storage namic and stratification process ofmal stratific
ited that of nt loss of taof a cycle (c
of the later ks) being th
close to thulated to age structureare a variatiheat is tran
consider thratio of theolume the l
of the uppera but needsower volumeneed exca
struction an
own by Pavlpits. Howevof the stora
fluid layers erty in a Te TES is inss the heat on thermats quantificad by its extrthermal liquor withdra
uction fromuses.
is represengeometric n appear tof these devation have
f Bahnflet annk height) charging an
is the gravehe storage m
he ground avoid heat es so far canion of this osferred thro
he optimizae volume toower the h
r part of thes more voluetric capaciavation opend the struct
ov and Olever, the studge is increa
of differenES. Thermastalled (i.e. t losses andal stratificatation have reme weaknuid storage awn phases the hot la
nted by theconditions.o be an attrvices. In thebeen defin
nd Musser [evaluating d dischargi
1
el‐pit storagmedia a co
surface to losses. Co
n be found ioption in a cough wall m
ation of heao the heat theat losses
e storage, aume to stoty of the filerations or ture is quite
nsen [PAV1dy also poinsed.
t temperatual stratificatsolar thermd increasestion within been propness. Amoncan be me; the heat ayers to th
e transient However, active tool e last decaed and can
[BAN98], whthe capacitng). The los
14/12/2014
ge, where thmbination o
avoid costmprehensivin Novo et aconfiguratiomounted hea
at losses antransfer areand thus th
as it is burieore the samler materiasuch a large visible.
11] that monted out th
ure due to ition not onmal systems the overathe tank ha
posed [CRI0g the severentioned: thlosses to the cold one
temperaturquantitativfor reportinde, differenn be found
ho calculatey lost due tst capacity
he of
tly ve al. on at
nd ea he
ed me l). ge
ost at
ts nly ms, all as 3, ral he he es;
re ve ng nt in
ed to is
defined as They also udistributionthe tank w
Davlevel of tesimilar to ais calculateideally fullyanalytical mbalance in the fully str
Varcompare ddifferent leanalysis caThermodynprocess of consequenthis degradexample ofconsideringthe exergy temperatustratificatioafter a cotransient n
A qfound in [H
Addthermal str
1.3
Theknowledgeassociated and design
Deson global mand‐error atransfer co
Themore effici
the capacitused the then inside thehich contain
vidson et almperature an energeticed as a funcy stratified models. Ththe tank, wratified situ
ious worksifferent temevels of temnnot accounamics provloss of strace, a degradation, quaf this kind og both char of the discre stratificon the highmplete cycature of the
uite compleHAN09].
ditional comratification a
Modelling
e design ae of the thwith the bers.
signs are vemass and enanalysis usinefficient in
e importancient in term
ty that cannermocline the tanks. The ns a therma
. [DAV94] astratificatioc momentution of the tank and ce complete
whereas the ation.
in the litemperature dmperature, unt for the vides an atification (dadation of tantifying itsof analysis. rging and dicharge procation in ther the valucle of charge process
ete review a
mments on are introduc
g of therma
and optimishermal andbehaviour of
ry often basnergy balancng prototypconvection,
ce of one‐dms of CPU t
not be remohickness as thermoclin
al transition
and Adams on by weighm). The dimlargest andcompletely ely mixed tplug flow m
erature repdistributioneven if thedegradationlternative wdue to fluid the energy s quality. TIn his workscharging pcess to the che performue of the eging and d
about the d
the particuced in the r
al storage t
sation of td fluid dynf these dev
sed on simpces or one‐dpes to provi, pressure lo
imensional ime cost an
oved from aan illustrati
ne thicknesslayer betwe
and Davidshting the emensionless smallest vamixed tanktank situatiomodel is use
port that ans. Energy aese tanks hn of the enway to evamixing, envstored. ExeThe works cks, he has dprocesses. Echarge procmance of xergy efficiischarging
different wa
ularities of esults sectio
tanks
thermal stnamic phenvices, make
ple mathemdimensionalide the necoss coefficie
models relnd suitable
a tank due tive paramets is defined een warm a
son [ADA93nergy storeenergetic malues of thek). These idon is obtaied to predic
n energy analysis cannhave equivaergy storedaluate the qvironment lorgy analysiscarried outefined exerExergy efficicess. This pthe storagency. Howeof the stor
ays of quant
Ecovat regaon.
ratified stonomena invoptimised
matical model models), aessary inforent, mixing
ays in the for use into
o an outlet ter to charaas the vertiand cool wa
3] proposeded by its vemomentum energetic mdeal situationed by mect tank temp
analysis counot distingualent energyd. In this sequality of tosses, etc.) s can be tht by Rosen rgy efficiencency is thenarameter she tank. Thever, this pre, being d
tifying therm
arding the
orage tanksvolved. Thedesign a ch
els (analyticnd/or expermation forparameters
fact that tho overall en
1
temperatuacterize the ical region oter volumes
d a way to ertical locat defined as momentumons are evaeans of a gperature dis
uld not be uish betweey quantitiesense, the Sethe stored creates enten a tool fo[ROS99,RO
cy over a clon defined ahows the imhe higher parameter isdifficult to
mal stratific
exergy ana
s requires e complex hallenge for
cal methodonsive experr these mods, etc. ).
hey are comnergy‐system
14/12/2014
re limitatiotemperaturof fluid insids.
measure thion (which MIX numbe (considerinaluated usinglobal energstribution fo
sufficient ten tanks wits, i.e. energecond Law oenergy. Thtropy and, bor evaluatinOS01] are aosed systems the ratio omportance othe storags only usefconsider th
cation can b
lysis and th
a profounphenomen
r researche
ologies baserimental triadels (i.e. hea
mputationalm simulatio
n. re de
he is er ng ng gy or
to th gy of he by ng an m, of of ge ful he
be
he
nd na rs
ed al‐at
lly on
programs wthe focus stratificatio[KLE93], belevels. Othproposed inecessity oresults dep
On Stokes andbehaviour fluid dynamof these syand in spitare still veFurthermostorage tanthe transie[CON04, RO
2. De
Thestudy addre
i) ii)
In oreasonableconcept is
To cthe storagrequired fodimensionaproblem un
which allowof attentioon have beeing the deher kind of in the literaof empiricalpends on the
the other hd energy eof storage mics and heystems. Howe of the usery costly. re, due to tnks, CFD&Hent heat tranOD09, ROD0
finitiono
e present stesses the qu
RegardiRegardi
order to ade simplificathere used.
carry out the will be cor performinal modellinnder study.
The mo[KLE93]dividedthis app
The fludifferenhere neconduct
w long‐termn of many en developgree of straone‐dimen
ature (e.g. l‐based infoe accuracy o
hand, detailequations stanks. In theat transfer wever, detae of paralleYet, there the lack of eT have beensfer proce09b, PAP09,
ofthecas
tudy focuseuestions po
ing the efficing the strat
dress the mtions but w
he performacarried out.ng a thoroug of the stThe main h
odel used f. As aforem into differeproach, it is
id in the tnces are coeglected. Ation betwe
m simulationresearcher
ped. Some atification dnsional app[ZUR88,NEormation toof the exper
ed models should be he last deca(CFD&HT) cailed numeel computerare some
empirical inen also usedss inside su, ROD13].
sesofstu
es on the thosed by the
ciency of thetification of
main issues which allows
ance analys. However, gh study oftore and a hypotheses c
for simulatimentioned, tent levels oconsidered
ank has a onsidered wlthough theeen the dif
ns. For this rs. A great of these mdetermined proaches toL99]). The o evaluate mrimental coe
based on thcapable ofades, detailecodes have rical simulars and efficiworks whformation ad in order touch equipme
dy.Aima
hermal and Kic Review C
e device, whf the storage
raised by ts estimating
is, a study oconsiderin
f the prototyseries of hconsidered
ing the behthis is a oneof temperatd that the vo
one‐dimenwhereas rade multi‐nodfferent lev
reason, onnumber of
models are by the cho
o account fmain problmixing at thefficients an
he multi‐dimf describinged numericemerged asations demaient parallehich take aabout the ho obtain coent. Among
andscope
exergetic sCommittee
hich is claime.
the Kic Revg the long‐
of the chargng the limitype, the scohypotheses are:
haviour of e‐dimensiontures which olume of ea
sional behadial and azimde model oels of tem
ne‐dimensiof simplified based in thoice of the for mixing em of suchhe inlets. Thnd their suit
mensional rg the thermal simulatios a powerfuand large cl algorithmsdvantage oheat transferrelations cg of these w
e
study of thewhich are s
med to be of
view Comm‐term perfo
ging, idle antations of tope of this sin order t
the tank isnal model w can be or ch tempera
aviour, i.e. muthal temriginally did
mperatures,
1
onal modellimodels to
he multi‐nonumber of at the inleh kind of mhus, the vatability for s
resolution omal and flons using coul tool for thomputations, long termof CFD&HT r coefficienapable of cworks can b
e ECOVAT cspecifically:
f 93%
ittee a modormance of
nd dischargithe computstudy is limito simplify
s the multi‐where the tanot of the ature level is
only axial mperature vd not consithe prese
14/12/2014
ing has beeo account foode approactemperaturt have beemodels is thlidity of sucsuch models
of the Navieuid dynamomputationhe predictional resourcem simulationsimulation
nts in thermcharacterisinbe mentione
concept. Th
del based othe ECOVA
ing phases otational timted to a onthe comple
‐node modank volume same size. s the same.
temperaturvariations ader the axient approac
en or ch re en he ch s.
er‐mic al on es ns ns. al ng ed
his
on AT
of me e‐ex
el is In
re re ial ch
Regto eCFDcancauby impresu
2.1
A mmain chara
ECObelow the outer concand dischamodules odifferent si
considetank wa
Even ththat whimply alayers dto the obtainethe othterm bea foreca
As the neglectallow tevaluattherma
The heataking aconvecttransferthermathe wat
Heat trthe tem
For theimpose
garding the sevaluate proD&HT mode only considse of de‐strmodifying tpact of an inults, a qualit
Descriptio
more detaileacteristics d
OVAT concesizes of eacrete walls. Aarging the of heat exczes of the E
ers axial conalls and the
hough the then a high high level due to advetank walls. ed numericaer hand, wehaviour of ast of the av
number oed, among he quantifited, multi‐dl behaviour
at exchangea uniform tative thermar correlationl resistanceter surface.
ansfer coefmperature d
e heat lossed.
second issuoperly the delisations shder axial coratification the water tncreased cotative analy
on of the EC
ed descriptiimensions a
pt is proposch of them aAnother intstorage mechangers. TECOVAT con
nduction befluid.
ank is dividnumber of of accuracyection, nor tIn this kindally does nohat this kinthe systemverage perfo
of temperatother simpcation of tdimensionar of the stora
ers at the tank side temal resistancns and variae due to theThe heat lo
fficient betwifference, a
es at the di
e, the scopedegree of sthould be caonduction ain storage dthermal cononductive hysis of the st
COVAT con
on of the Eand working
sed in 4 maiare given. Thernal wall wedium. Thehis modulancept (Table
tween the d
ded into N ttemperatu
y, as the mothe laminar d of approaot always red of model. Thus, the oormance du
ture levels plifications, he stratificl models cage should
tank walls amperature fces on bothable thermae concrete losses to the
ween the tare taken fro
ifferent tan
e of this sturatification rried out. Itnd the mixdevices. As nductivity cheat betweetratification
ncept
ECOVAT cong conditions
in dimensiohe main conwith embedse inner warity is whae 1).
different lay
temperaturere layers aodel used caor turbulenach, the inseproduce thling provideoutcomes ouring a perio
is imposed1D modelsation in thconsidering be used ins
are considerfor each Ecoh fluids (byal propertiesayer existinenvironme
ank walls anom literatur
nk walls an
udy cannot geither ad hot is importaing it produwill be obsecan be donen layers. In issue is giv
ncept can bs are briefly
ons dubbed ncept consisded heat ex
walls are coat allows e
yers and the
e layers it hre imposedannot consint boundarystantaneoushe actual bees is a fair aof such modod of time.
d and adves such as te tank. If tthe detai
tead.
red with anovat layer. Ty applying s on both sing betweennt are not c
nd the fluidre available
overall hea
give a concloc experimeant to remauces, whicherved later,ne to evaluan the correen.
be found in summarize
ECOVAT S,Msts of a cylinxchangers isnstructed beasily const
1
e heat trans
has to be bod it does noder the mixy layers devs behaviourehaviour of agreement wdels should b
ection mecthose used this propertled fluid d
n adapted εThe model claminar+tuides) and th the serpenconsidered i
, although vcorrelation
at transfer
usive answeental set‐upark that theh is not by f only sensitate the de‐esponding s
[BER14]. Hed.
M, L and XLndrical buris the meansby assemblructing and
14/12/2014
sfer betwee
orne in minot necessarixing betweeveloped closr of the flothe tank. Owith the lonbe devised a
chanisms ahere do noty has to bdynamic an
ε‐NTU modeconsiders thrbulent heahe conductivntine coil anin the mode
variable wits.
coefficient
er as in ordeps or detailee model usefar the majotivity analys‐stratificatioection in th
ereafter, th
L. In the tabed tank, wits for chargining differend assemblin
en
nd ily en se ow On ng as
re ot be nd
el, he at ve nd el.
th
is
er ed ed or sis on he
he
ble th ng nt ng
Giveand heat trin the table
Tab
ECOVA
S
M
L
In tresistance foam glassdynamicalland the flu
Takdirection, iindependework and bpoint of vilayers at dito be detethese devicbetween thnear the w
en the dimeransfer areae as the pre
ble 2: Geome
AT model
this study, of the diffes, EPS, sany evaluatedid as a func
ing advanta.e. the totantly and /obe charged/iew. Howevifferent temrmined by uces. In this he tempera
walls, therma
ensions of tas are givensent study i
etric estima
Volume [m
1520.53
4071.50
19113.45
the walls erent layersnd‐water, d within thection of the t
age of ECOl height of tr at differen/dischargedver, the levmperatures dusing detailstudy, onlyature levelsal bridges ca
Table 1: Dim
ECOVAT mo
S
M
L
XL
he differentn in the Tablis carried ou
ation of the
m3] Totatrans[m2]
742.9
1413
4349
are consids composingsoilmix cone code evalutemperatur
OVAT moduthe tank is snt temperatd at differenvel of mixinduring the cled models y a rough ess can be givaused by th
mensions of
odel He
t ECOVAT mle 2. Notice ut for the fir
volumes an
l heasfer are
99
3.72
9.54
ered as layg the laterancrete, etcuating also tre of the sto
larity, thessegmented itures. This dnt temperatng (loss of scharging/disor ad‐hoc estimation oven. Mixing he walls of t
f the ECOVA
eight[m]
16
16
16
16
models, a gethat the ECrst three pro
nd heat tran
at a
Lateral [m2]
552.92
904.78
1960.35
yers of difal walls are c.). Overall the heat traorage mediu
e models ainto 5 levelsdistributiontures might stratificatioscharging phexperimentof the mixindue to devhe heat exc
AT models
Diameter[
11
18
39
58
eometric estCOVAT XL coototypes.
nsfer areas o
surface
5
fferent mattaken intoheat loss
ansfer coeffum.
are also segs, which cann into differebe interestn) that wohases and aation for thg due to thveloped turchangers, co
1
[m]
timation of oncept was
of the proto
Top/bottomsurfaces [m
95.03
254.47
1194.59
terials, i.e. account (es coefficienficient betw
gmented inn be chargeent segmenting from a uld be prodalso in the idhe working che axial hearbulent bouonvective p
14/12/2014
their volumnot include
otypes
m m2]
the therme.g. concretnts are theween the wa
n the verticd/dischargents which castratificatioduced withdle phase haconditions oat conductioundary layelumes due t
me ed
al e, en all
cal ed an on in as of on rs to
temperatuthe boundcannot be c
2.2
Theplatform (ssystem or storage tanusing this m
The
i)
ii)
iii)
In tbottom waelement omodelling constrains,node modesuch as thocan be axiacan receiveconsidereddetermined
At econditions as the bousystem of convergencFor more d
2.3
In ocarried out
Tes
re gradientsary layers considered
Methodol
e implementsee [DAM11configuratink for concmethodolog
e main adva
any basic ere‐used in othe elemeconditions,1D approaremains unEach elemewithout an
he present all, embeddf the storathe storage in the presel), but theose used inal 2D or fulle a special d). Furthermd boundary
each time sfrom the lin
undary condequations ce is attainedetails abou
Descriptio
order to studt. The defini
st1:Cool‐d
s or eventudescendingwith the lev
logy used
tation of th1]) which aon. This plaentrated sogy can be fo
ntages of a
element proother systemnts which , being solvch by a 3Dnchanged anent of a givy need of re
implementaded heat‐eage more te medium, sent study te present mn [ROD09] bly 3D. This itreatment
more, eachconditions,
step, the gonked elemeditions for iis a Gaus
ed. Then, aft the genera
on of the te
dy the thermition of the
downofth
al thermal ig along the vel of mode
e storage taallows the liatform has olar power und in [ROD
modular ob
ogrammed ims; form a deed indepen
D approach)nd, ven system e‐writing an
ation the stexchanger lthan one mdifferent l
the storage methodologby substituts one of the from the h of these , which can
overning eqents whereats neighbouss‐Seidel likfter updatinal algorithm
ests.
mal behaviotests is give
hestorage
inversion, flwalls and
ellisation use
ank methodinking betwbeen prevtanks with D13].
bject‐orient
n a general
etermined ndently whic while the
can be solvny part of th
orage tank ateral wallsmodel apprevels of mmedium is y can reading the obje advantagephysical poelements be obtained
quations ofas at the samurs. The alke algorithmng the variam the reader
our of the Een hereafter
e. In this tes
ow entrainirrupting ined in the pr
dology has bween differeiously usedgood resul
ed tool are
l way can be
system intech allows threst of the
ved using ahe code.
is consideres, top wallroach can bodellisationtreated witily be exteect “multi‐nes of a modoint of view(objects) id from the
f each objeme time, thegorithm usm, in whichbles, the algr is referred
ECOVAT storr.
st, the tank
ments due tnto a layer resent study
been made ent elemend for modelts. Validatio
e used in a
eracts onlyhe change oe elements
a different
ed as the sul, storage mbe considen can be coth a one‐dimnded to munode” by a ular methow (i.e. diffeis capable neighbourin
ct are solvee outputs oed for the h iterationsgorithm goed to [DAM11
rage, four d
is initially a
1
to jets effecat similar
y.
within the ets to perfolling the beon and resu
given confi
y through iof a given mwhich form
parallelizati
um of differemedium, ered. For eonsidered. mensional multi‐dimensCFD&HT mdology, as erent hypotof solving ng elements
ed taking tf each elemresolution os are carries to the ne1].
different tes
t a tempera
14/12/2014
cts caused btemperatu
existing NESrm a specifehaviour of ults obtaine
iguration an
its boundamodel (e.g.m the syste
ion paradig
ent parts e.tc. For eacexample, foDue to timmodel (multional modemodule whiceach elemenhesis can bitself give
s (objects).
he boundament are useof the whoed out untext time ste
sts have bee
ature of 90º
by re
ST fic a
ed
nd
ry a m
m
g. ch or me ti‐els ch nt be en
ry ed ole til p.
en
ºC
and is submdays, accorstudy has bare shown
Tesconstant teThe chargin12ºC. The exchangersexchangersheat exchamaximum thuge time the HTF. Ofluid circulaThe next fprocess is 2
Aftetest consistWith theseflow rates these phas
Theworking cothis is not to the systedetail in th
Tesconcept. Inlevel reachis still beingcirculating at constant
Tesconnectio
mitted to hrding to [BEbeen carriefor ECOVAT
st 2: Fullemperatureng process dcharging is s in the wals operating anger, up untemperaturwould be rence the firsating now tluid layers 2000h.
er that, the ts of dischae three phashave been es are taken
ECOVAT model
S
L
e charging/donditions of the only poem in whiche results se
st 3: full cn fact, this thes an 80% og charged. through tht rate at the
st 4: heaton As the re
heat losses ER14], from d out for ET M.
cycle of ce and mass duration is 2accomplishl. The load oat differen
ntil the temre differencequired in ot (topmost hrough the are charged
tank is subrging the tases a compadapted fron from [BER
Volumethrough
discharging the tank. O
ossible operh it is instalction.
cycle chargtest is similof the maxiIn this case,e lateral hee same time
t exchangesults of Tes
to the enviwhich perfCOVAT S, M
charging/dflow rate th2000 hours,hed by circuof the tank nt heights, tperature in e (75ºC levorder to raislevel is charsecond levd in a simil
bmitted to aank at constlete chargeom conversR14] (all sum
Table 3: In
etric flow ra 1 layer [m3
6.50
23.64
of this testOf course, drating modeled should b
ge/discharlar to test 2imum differ, as the folleat exchange.
ger influests 2 and 3
ronment (sformance inM and L but
discharginghrough the , and the iniulating the htakes placethe hot fluid the core ofel in the rase the temprged), the nel whereas ar form as
a cool‐downtant tempe/discharge ations withmmarised in
nlet conditio
ate 3/h]
Char
t have beenue to the pes for this cbe found fo
rge. This is 2, but in thrence, the nowing levelers increase
ence on toutlined th
soil) at 12ºCndicators in t for compa
g. In this teheat exchaitial tank unhot heat trae from top td is first cirf the tank ange 12‐80ºCperature in tnext heat exthrough thethe topmo
n process orature and cycle is acc Ecovat comn the Table
ons for tests
rge inlet tem[ºC]
80
80
n designed sossibilities toncept, butor each case
another pois case, oncnext level stls are beinges as more
the chargehe importan
C during a lKIC questioarison with
est, the tanangers embeniform tempansfer fluid o bottom. Arculated thrt the topmoC). Otherwithe tank at txchanger laye other leveost one. The
of 180 days.mass flow romplished. mpany, whi3).
s 2 and 3
mperature
so as to mithe modulat the optime. This aspec
ossible opece the temptarts being c charged, thlevels are b
e/dischargnce of the c
1
ong‐term pons where o[BER14] de
nk is initialledded in thperature is c(HTF) thro
As the tank rough the tost level is 9ise, it is supthe inlet temyer is activaels no fluid e whole du
. The third rates duringThe detailsle temperat
Dischatempe
mic one of ar heat exchum which bct has been
rating modperature in charged buthe total mabeing charg
ge operatcharge/disch
14/12/2014
period of 18obtained. Thtailed resul
y charged ahe tank wallconsidered augh the heahas five heaopmost lev92.6 % of thpposed thatmperature oted, with this circulatinration of th
phase of thg 2000 hours of the mature levels o
arge inlet rature[ºC]
12
12
f the possibhangers offebetter adapn explained
e of ECOVAthe topmot the top onss flow rateed in parall
tion; serieharge contr
80 he ts
at ls. at at at vel he a of he g. he
his rs. ss of
ble er, pts in
AT ost ne ed el
esol
in terms ofto bottom most adeqstudy has bby the 1D minlet at 80ºbottom lay
Theindicated exchanger.(flow rate dsize).
3. Re
3.1
Thestorage is performanECOVAT Mnegative exstore was apointed oulayers whein current sefficiency o
F
Beinend of the
f energy/exe(charge) anuate to obtbeen done multimode)ºC to buffeyer inlet at 1
e developmsome impo. Those condependence
sults
Test 1 res
e average tegiven in Fce indicato. As expectexponential wabout 80ºCut that in [Bre simplifiestudy), resuof the device
igure 1 ‐ EC
ng the thercool‐down
ergy managnd bottom ttain the ouby using the. The situatr at 12ºC) i12ºC to buff
ent of the ortant conclusions aree, importan
ults
emperatureFigure 1 forors cited byed the averwith time. A. This valueBER14] heatd (only oneulting in a sle.
OVAT Test 1process. (r
mal efficienprocess to t
gement, theto top (disctlet water te heat exchtion has beemmediatelyfer at final c
heat exchaclusions one highlightence of concr
e variation ar Ecovat S,y KIC questiage temperAt the end o is a tad lowt losses thre layer of 30ight differe
1 results. (leright) Cumu
ncy of the dthat contain
case of thecharge) has temperaturhanger moden simplifiedy followed bconditions o
anger modn its perfoed in these rete distanc
and cumula, M and L.ions whererature in theof the cool‐wer than though the to00 mm insulnce in the o
eft) Averageulative heat
device definned at the b
e heat exchabeen analy
res closest tel in a five d to one chaby an equivof the charge
el and its ormance acharge+disce between
ative heat lo For comp obtained) e store duri‐down procehat obtainedop of the dation considoverall heat
e temperatulosses per u
ed as the rabeginning of
angers connysed becausto the tank layer‐five earge of 200valent dische period).
testing agand the intcharge resuserpentine
osses durinparison withthese resung the cooless the aved by [BER14evice were dered vs. tht losses and
ure variationunit volume
atio of the f it,
1
nected in sese it is knowlimit temp
exchanger a0h (serpentharge period
ainst a one ter‐relationults on the wand water
ng the cool‐h [BER14] ults are plo‐down procrage tempe4]. However neglected he multilayea slightly lo
n along the e.
energy cont
14/12/2014
ries from town to be thperature. Thpproach (notine top layed (serpentin
buffer laye buffer‐heawhole Ecovasurface, tan
‐down of th(from whertted also focess followserature in thr, it has to band the waer considereower therm
cool‐down
tained at th
op he his ot er ne
er at at nk
he re or s a he be all ed al
he
The
NotThese diffetop are nelayers whicespecially volumetric
Anowalls of the
ECOVAT
S
M
L
Whthat even warea), the rwalls is nenegligible. thereof maaspect woubetween th
As aEcovat walconductivit
e energy effi
Table
ECOVAT concept
S
M
L
tice that theerences caneglected andch form thfor those o energy loss
other issue e tank. In th
Qlos
[MJ
90.4
174.1
540.9
en it comeswhen the laratio by squarly the samHowever, aakes energyuld be consihe extra cos
a final commllparts has ty of 0.034
iciency of th
4: Cool‐dow
Qloss [M
e efficiency be attributd ii) here the compositof larger vses are lowe
to be consihe following
Table
ss
]
47 6
18 1
97 2
s to the disarger deviceuare meter me and theanalysing thy losses by hidered as anst of the bot
ment, the inbeen analyW/mK. Alt
1
he ECOVAT
wn test. Ene
MJ]
90.47
174.18
540.97
of ECOVATted to two hermal reste wall. Noolumes, in er.
idered is thg table, thes
e 5: Cool‐do
Qloss latera
[MJ] [
68.03
112.29
243.31
tribution ofe is the oneof wall areae influence ese losses iheat transfen improvemttom insulat
nfluence of tysed by conthough the
concepts S,
ergy losses a
Qloss/V
T M is lowerdifferent soistance of tonetheless, which due
he distributie losses are
own test. En
al wall
[MJ/m2]
0.123
0.124
0.124
f the energye with largea is the samof the temt is evidenter area throment in thesetion and the
the thermalnsidering thjoint gives
M and L is
and efficien
V [MJ/m3]
0.06
0.043
0.028
r than that ources: i) in the walls isthe efficiee to the la
on of the ee given.
ergy losses
Qloss to
[MJ]
6.54
18.05
86.92
y losses threr energy lome in all devmperature o that the poough the boe devices, be cost of the
l bridge cauhe indicateds a relative
given in the
ncy of the EC
claimed at [BER14] en
s consideredncy of the arger volum
energy losse
through wa
op wall
[MJ/m2]
0.069
0.071
0.073
rough the wosses (due tvices as the f the fluid oor bottom ottom the labut of course energy sav
sed by the pd width andly low insu
1
e following t
COVAT conc
81.50
86.72
91.22
[BER14] (86nergy lossesd accountindevices is
metric therm
es through
alls.
Qloss bo
[MJ]
15.90
43.83
21.073
walls, it can to a larger structure oin the wall insulation oargest of the it has to bved for this
polymeric jod depth, anlation comp
14/12/2014
table.
cept
6% vs. 90 %s through thng for all thrather hig
mal capacit
the differen
ottom wall
[MJ/m2
0.167
0.172
0.176
be observeheat transfeof the layereresistance or the lack ohe three. Thbe a trade‐oconcept.
oint betweend a thermpared to th
%). he he h, ty,
nt
]
ed er ed is of his off
en mal he
wallpart, tha 1.5%). Ntank waterwould bypa
3.2
The
Bein
In tvolume, h state, i.e. t
Simexergy chacharged atcharging prthe temper
The(Figures 2 the time ra[BER14] to fully chargecharging aevolution wheating‐upthe layer temperatutank. For tthrough thof upper la
TheTable 6. Aexergetic ephase is giheating effexergetic elevel.
he high wideverthelessr and the sass the wall
Test 2 + Te
e exergy effi
ng
the above eand s are the state of t
milarly, an exnge during the temperocess is frorature at wh
e obtained rand 3) and ange of 200which the qed, while Ecnd dischargwithin the tp process, asaverage tere mainly vest 2 (Figure wall. For yers contin
e reported As can be oefficiency cving valuesficiencies arefficiencies
th ratio bets, the continand‐water parts insula
est 3 result
ciency of th
equations, Ξhe specific thermodyna
xergy efficiethe charginerature of thom the ideahich it is bei
results showexergetic e
00 h was selquestions frcovat L is stging strategtanks. Apars in this casemperaturesaries in thare 2), the ptest 3 (Figuues their he
energy andobserved, tomparing t between 5re related wshow a str
tween bothnuity‐integrbehind the ation in a se
ts
he whole cyc
Ξ
Ξ
Ξis the exeenthalpy aamic equilib
ency for theg process tohe inlet fluidl situation. ing charged
w a great defficiencies ected in corom KIC whetill far from gies have art from the e a heat excs and the t part of thpassive layere 3), as all eating up to
d exergy effhe energy the injectio50% (Ecovatwith the chong link wi
makes therity of this j wallpart iserious way.
cle can be d
Ξ
ergy at the nd entropy brium with t
e charging po that it wod. This wayIn other wo?
ifference be(Table 6). Tmparison toere formulathis status.
a direct impheating evchanger covcontrol stre buffer, rers slightly dthe active
o the limit te
ficiencies foefficienciesn of chargt L at test 2arge/dischaith the char
influence ojoint in avos a key aspe
defined as,
Ξ
Ξ
given statewhereas ththe natural
phase can buld theorety, it would gords, is the s
etween EcoThe focus heo the previoated. For thi. However, pact on thevolution, it ivering each rategy. Duremaining almdiminish thelayers mainemperature
or the fours are high ing phase w2) to 80% (Earge level orge/dischar
of the joint oiding any leect to avoid
es, is the she sub‐indesurroundin
e defined aically be if tgive an ideasystem capa
ovat S and Lere should ous indicateis time rangit can be ree temperatis also obselayer is switing the chmost unchaeir temperantain their ae.
r cases conand similarwith the exEcovat S or of the tank.ge mode a
1
very small (eakage betd a therma
specific exeex ‘0’ indicags.
as the ratio the tank woa of how cloable of stor
L temperatube given toed value froge, the Ecoveadily obserure, energyerved the latch on/off darge of onanged for thature due toactivity, the
sidered arer to test 1 xtraction ofEcovat L at As outlinend the ach
14/12/2014
(estimated ween the ial bridge th
ergy, V is thates the dea
of the actuould be whoose or far thing energy a
ure diagramo Ecovat S, aom the repoat S is almorved how thy and exergayer by layedepending one layer, thhe rest of tho heat lossetemperatur
e depicted results. Thf dischargint test 3). Thd above, thieved charg
in n‐at
he ad
al le he at
ms as ort ost he gy er on he he es re
in he ng he he ge
Figu
Regof the equenergetic pin a more and 5, theindicative rmore comsignificantl
Case Co
1 S‐
1b S‐
1c S‐
1d S‐
2 S‐
3 L‐
3b L‐
3c L‐
3d L‐
4 L‐
ure 2 ‐Test 2
garding the uivalent turperformancor less relee mixing efresults of an
mplex showiy different t
onditions
‐Test 2
‐Test 2 Keff=
‐Test 2 Keff=
‐Test 2 Keff=
‐Test 3
‐Test 2
‐Test 2 Keff=
‐Test 2 Keff=
‐Test 2 Keff=
‐Test 3
2: Water ta
effective thrbulence me is slightly vant way dffect of then equivalening local btemperatur
Table 6: T
8
=1 8
=3 8
=10 7
8
9
=1 9
=3 9
=10 9
9
ank tempera(left) Eco
hermal condixing for ereduced, wepending oe increasedt enhanced
behaviours re maps tha
Test 2 + 3 pe
80.53
80.23
80.09
79.52
80.49
91.84
91.83
91.43
90.80
92.93
ature evolutovat S. (right
ductivity tesnhanced cowhile the chon the tank d thermal dd mixing by like boundn those rep
erformance
,
77.38
77.99
78.23
73.72
79.67
50.72
50.36
40.12
35.11
88.31
tion with timt) Ecovat L.
sts, the resuonductivity harge/dischasize and chdiffusion is diffusion, aary layers ported here.
results.
me (each lin
ults indicatevalues higarge exergeharge/dischclearly obs convectivat the wa.
1
,
95.96
96.43
82.80
67.64
99.86
36.99
36.10
27.22
34.19
58.64
ne covers a
e an importaher than 3etic efficiencarge mode.served. Thee effects coalls that wo
14/12/2014
100h range
ant influenc W/mK. Thcy is affecte. In Figuresese are onould be mucould lead t
).
ce he ed 4
nly ch to
Figu
Figu
Fig
ure 3 ‐ Test
ure 4 ‐ Test
gure 5 ‐ Tesrang
3 : Water ta
2 Keff Ecova100h rang
st 2 Keff: Wge). (left) Ec
ank temper(left) Eco
at S: Waterge). (left) Ke
Water tank tecovat L Keff=
ature evoluovat S. (right
r tank tempeff=3W/mK
emperature=3W/mK. (r
tion with tit) Ecovat L.
erature evo. (right) Keff
e evolution wight) Ecovat
me (each lin
olution withf=10W/mK.
with time (et L Keff=10W
1
ne covers a
time (each.
each line covW/mK.
14/12/2014
100h range
line covers
vers a 100h
e).
s a
h
3.4
As connected flowrate (owork as a s
Theperiod (6.5reference bcenter of tdrawings fr
Thetemperatutransferredtank is heaan examplechange in tmode, the contributiolayer with bottom tan
Test 4 res
introduced in series, wotherwise fusingle tempe
e reference 5m3/h), andbuilding floothe serpentrom the Eco
F
e obtained rre of each d by layer. ted faster te, look howtemperaturwater leave
ons in heat ttime. The nk layer.
ults
previouslywhich is expeull charge werature buff
case has tad the averor heating ctine coil toovat compan
Figure 6‐ EC
results (Figulayer, the inIt can be imthan with thw, at initial re from 80ºes (layer 5, transfer frooutlet serp
y, in this caected to bewith all layerfer.
aken Ecovarage indicatcase. On theo the tank wny.
COVAT S Tes
ures 6 and ntermediatemmediatelyhe consideretime, the fiºC to 50ºC, bottom) th
om each layepentine wat
ase the he the mode ors in paralle
t S at the mted flowrate other hanwater surfa
st4‐charge:
7) show thee inlet/outley identified ed charge mirst layer (towhile addi
he Ecovat wer have alsoter tempera
eat exchangof maximumel will be th
maximum ite for the nd, an averaace has bee
baseline ge
e evolution et heat excthat with t
methods in top) heat exng the othe
with a tempeo been showature rough
gers of them heat trane fastest) if
ndicated flodischarge
age concreteen consider
eometry and
(charge+dichanger temthis connectest 2 and txchanger in er layers coerature of awn, depictinhly follows
1
five layerssfer operatf the tank is
owrate for period (2.0e thickness red from th
d flowrate.
scharge) ofmperatures ction methotest 3 (layerthe charge
ontribution about 18ºC.ng the evoluthe temper
14/12/2014
s have beeion at a fixes expected t
the chargin0 m3/h) in between thhe submitte
f the averagand the heod the whor by layer). Ae mode has in this serie. The relativution of eacrature of th
en ed to
ng a
he ed
ge at ole As a es ve ch he
For has been into 2 m3/h)to top). Thecase layer local tempehighest temlayers, the temperatuis expectetemperatuas a heat atemperatucondenser focus shouuseful eneexample in(which is de
As abeen analyflow rate,temperatu
Figure
the discharncreased su. The rest oe leaving se1; with a reerature varimperaturesin‐tank watre. An impod to recovre after a caccumulatore; as long loses voltald be movergy is that n floor heatiesired to be
assumed asysed in the the dischres also leav
7 ‐ ECOVAT
rge mode, oubstantially of conclusioerpentine wedesign of tiation withi. However, ter reduces ortant commver the maertain perior, increasinas heat is eage as curred to the reawhich coveng around 3e maximum
an interestdischargingharge procve the tank
T S Test4‐dis
one can readue to the ns are similater tempethe serpentn the tank, in this casits tempera
ment comesass of wateod of time (ng the energextracted thent is extracal water outers the tem30ºC), indeto reach th
ting and relg process. Incess is accat lower te
scharge: bas
adily observreduction inlar to the chrature againtine circuit the outlet tse, as long aature and ths at this poiner stored aas in Domegy stored dhe temperatcted from itlet temperamperature lependently fhe limit in en
evant resuln the Figurecelerated, mperatures
seline geom
ve how the n flow rate harging pron follows thand considetemperatureas the heathis is translant: Ecovat isat one temestic Hot Wadensity by rture drops, t. From ouature needeevel neededfrom the manergy stored
t, the effece 8 it can bwhile the s, following
metry and flo
time needecomparing cess but in e last buffeering in thae will probat is extracteated to the s not an opemperature ater tanks). ising its temin an analor point of ved in the Ecd in the paaximum temd density).
t of serpentbe observedcorresponthe tank te
1
owrate (2 m
ed to dischato the chargan inverse
er layer in coat case in thably extend ed from theoutlet serpen storage tat the clos Converselymperature vogous way aview, here tcovat applicaarticular apmperature o
tine water fd how with ding serpemperature
14/12/2014
m3/h).
arge the tange process way (bottoontact, in thhe model ththe region e tank uppepentine watetank where sest possiby, Ecovat acvs. the initias an electrthe exergetation, that iplication (foon the Ecova
flow rate haan increaseentine watedecay.
nk (6 m his he at er er it
ble cts al ric tic is, or at
as ed er
Fig
F
Fig
Anoidentificatithe naturalayer separdominant simulated
gure 8 ‐ ECO
igure 9 ‐ EC
gure 10 ‐ EC
other intereon of the dl convectionrates the sefactor. In in order to
OVAT S Test
COVAT S Tes
COVAT S Tes
esting aspecdominant hen within theerpentine fFigures 9 o visualize
t4‐discharge
st4‐charge: m
st4‐discharg
ct of the heeat transfere tank, but from the taand 10, a the possibl
e: baseline g
minimum com3/h).
ge: minimumm3/h).
eat exchangr resistancein other caank water, situation wle improvem
geometry an
oncrete geo
m concrete g
ger vs. tank. Dependingases, for exathis insulatwith negligments that
nd maximum
ometry and
geometry a
k interactiog on the caample whenion‐like congible concrecan be de
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nd baseline
n analysis hse, the limin an importncrete layeete thickneevised in th
14/12/2014
of 6.5m3/h.
owrate (6.5
e flowrate (2
has been thiting factor tant concretr acts as thess has beehe Ecovat b
.
2
he is te he en by
addressingacceleratedis clearly leThe reasonthe heat exwhen apply
A catimes with both chargconnectioncharge andare the kcharging/din parallel analyse the
this aspecd in an impoess relevantn of this asyxchanger effying an imp
ase on the Ethose outliing and discn increase td discharge key issue tischarging oall layers ate energy/ex
Figure
ct. If we foortant way t, only exteymmetric befectiveness,rovement o
Ecovat L is fned in testscharging prohe charge astrategies tto improveoption to obt the same xergy recove
11 ‐ECOVA
cus on the(from 1000ending the ehaviour is , and if this on the heat
finally shows 2+3. The focesses, as and dischargogether wite Ecovat pbtain the fatime; this ery within a
AT L Test4‐ch
e charge pr0 h to 600 h)maximum sbased on tvalue is alreexchange p
wn in Figureflowrates haapplied in tge rhythm ith the heat performancestest energhighlights tclear statem
harge: base
ocess, it ca). However,serpentine he impact oeady saturaprocess.
s 11 and 12ave been mhe cited tesin an imporexchanger e to eachgy exchangehe flexibilitment of the
line geomet
an be seen, in the discwater outleof the wateated (maxim
2, in order taintained asts. The resurtant way, igeometry a particulare ratio couldty of Ecovate Ecovat goa
try and max
1
how the hharge proceet temperater serpentinmum heat flo
to compare t the maximults show hondicating aand operatinr case need be to chart and the imals in every
ximum flow
14/12/2014
heating‐up ess the effeture intervae flowrate ow rate give
the charginmum level foow the seriegain that thng conditioneds. Anotherge/dischargmportance tinstallation
rate.
is ct al. in en)
ng or es he ns er ge to .
3.5
As turbulent bconvective due to jets at similar teOnly a seconductivitThis has beW/mK no ichanges inmakes diff(dependen
Thevery compltime scale challenging
Figure 1
Stratificat
already intboundary laplumes dueffects cauemperatureensitivity anty of water,een done inmportant d both the eficult to takt on Ecovat
e quantificatlex task thaassociated
g task and
2 ‐ ECOVAT
tion analys
troduced pyers near thue to tempeused by the e cannot be nalysis can , substitutinn Tests 2+3 de‐stratificatexergy perfke conclusiot size and ch
tion of the tt needs the with largerestricted t
T L Test4‐dis
sis
reviously, che walls, theerature graboundary laconsideredbe carried
ng the real by raising ttion effectsformance (uons of theseharge/discha
thermal strae use of CFDe units makto small tim
scharge: bas
complex floermal bridgdients or eayers desced with the led out withconvective
the conducts have beenup to 4% foe results) aarge strateg
atification dD and/or exkes the preme ranges a
seline geom
ow structurges caused bventual thending alongevel of modeh the 1D‐m effect by ativity from 0 observed, or Ecovat S;and in stratgy).
degradation perimentatdiction of sand certain
metry and ma
res like miby the wallsermal inversg the walls aellisation usmodel by ean increase0.6 to 10 Walthough fo; for Ecovattification lev
in large‐sizion. Even instratificatioRa number
1
aximum flow
xing due ts of the heatsion, flow eand irruptinsed in the penhancing ed axial diffW/mK. For raor higher vat L the low vel have be
e heat storan the CFD can and its drs. The CFD
14/12/2014
wrate.
o developet exchangerentrainmeng into a layeresent studthe thermusive mixinange below lues relevancharge lev
een detecte
age tanks isase, the hugdisturbance D researche
ed rs, ts er y.
mal g. 1 nt vel ed
s a ge a rs
usually looand/or des
Whthat are iqualitative
Thewhich are tcompared boundariesinfluence h
In pconvectionlateral waldegrade prwalls, descdegrade thqualitativecalculated
Fig
For of the impoa stronger both aspeprotuberan
ok for analysign statistic
at we can indirectly asand coming
e pure condthose predito the convs. This hashas been det
passive or n movementls, a boundrogressivelycending flowhe existing sly the prevfor a very s
gure 13 ‐ Co
the Ecovatortant insulnatural co
ects togethnces on eac
sis of particcally station
introduce associated wg from our k
uctive effecictable by svective effes been contected only
cool‐down t because oary layer is y the tank tew structurestratificationvious commmall tank (2
oolDown of represent
case, the tation level.onvection mer with thch heat exc
cular tank zary represe
and analyzewith the stknowledge
cts produceimplified 1Dects occurrinnfirmed by for therma
mode, theof the tempecreated all
emperaturees develop dn. Figure 13ments for 200 l) in a la
small tank (ative time s
temperature However, t
movement (he geometrhanger leve
zones, analyentative test
at this statratificationand experie
ed in still strD 'multinodng in storagthe effect
al conductivi
e heat losserature diffl along the level and sdue to the 3 from a resa cool‐dowminar flow
(200 l): temstep during
e differencethe large tahigher Ra nrical particel) and the
yse the prots to reduce
ge are som and its dence in natu
ratified watde' codes, age tanks dutive thermaities 5 times
ses throughferences bettank heightsomehow thexisting te
search carriewn process case (Ra=6x
mperature (lthe cool‐do
es are expenk height isnumbers). cularities ofsmall aspec
oblem scalee the time sc
me commendisturbance.ural convect
ter (like thore well‐knoue to the inal conductis of water v
h the insutween the wt, creating vhe existing semperature ed out at CTstarting a
x1011).
eft) and velown process
cted to be s expected tUnfortunatef the Ecovct ratio (he
1
d at lower cale of the p
ts on the E. These indtion process
ose in lakes,own to be tynteraction wvity tests wvalue.
lation creawall and thevertical movstratificationdifferencesTTC [ROD09t isotherm
locity (right)s.
relatively sto impact oely, the comvat wallpareight/width)
14/12/2014
Ra numberproblem.
Ecovat desigdications arses.
, basins,etcypically smawith the solwhere som
te a nature fluid. In thvements than. On the tos, which als9b] illustrateal conditio
) maps for a
mall becauson developinmbination ort (double ) of the tan
rs,
gn re
.), all id
me
ral he at op so es n,
a
se ng of T k,
makes the high compu
Durheated/coostructures predominaDependingdifferent leshows the
Figu
A particboundary lstratificatiothe design changing thHere, a cotemperatupossible fube the use[ALT05].
Anotheto‐water hone layer tuseful temheating nee
From pbeen alreaheat excha
end de‐strutational de
ring the choled surfacis strongly
antly laming on the boevel with thresults obta
ure 14 ‐ He
cularity of Elayer will pon, and diffof the wallhe directionombination re differencture action of horizont
er innovativeeat pumps to the otherperature leeds, thus st
previous comdy pointed anger design
ratification eemand CFD
harge and e, creating dependentar and otoundary layhe core regained at CTT
at‐Up: Tem
Ecovat is thaprobably peiculting thepart, havingn of the maof smart wces, will prs in the destal baffles t
e action alrto recover r. This actioevel and hearongly spre
mments andout the stron and cond
effect of thstudies (eve
discharge a vertical
t on the coher whereyer strengtgion. Just asTC for a cha
perature ancavity (aspe
at only one netrate in t heating of g a protubeain plume frwallpart desobably mitsign of Ecovto reduced
ready considthe stratifi
on allows thating of theading the to
d from the eong influenditions in th
his convectiven in this ca
modes, bo'plume‐like
onfiguration turbulencth and the s an exampllenging tur
nd flow struect ratio 5,
part of thethe higher the corresprance at therom verticasign togetheigate thosevat coming fthe de‐strat
dered by Eccation levelhe cooling oe upper layeotal amount
exergy and ce of the chhe developm
ve movemease with res
undary laye' flow mov, creating cce (and cotank aspe
ple of the mrbulent natu
uctures founRa=4.5x1010
wall is beinlayer, destponding laye top of thel to some iner with a ree undesiredfrom this phtification pr
covat designls within thof the Ecovaers to allowt of useful e
heat exchanharge/dischment of the
ent only pretricted scop
yers develovement. Thcases whereonsequentlyect ratio thmentioned pural convect
nd in a turbu0).
ng heated, troying at ceyer core rege heated regnclination tefined cont mixing effhenomenolorocesses, as
ners is the ue tank by tat lower layw this energenergy.
nger‐fluid starge policy e tank strat
1
edictable bype as indicat
p all alonge nature oe the bouny mixing) iese plumesphenomenotion case [T
ulent natura
therefore thertain levelgion. On thegion, could owards thetrol to redufects. As anogical assess already po
use of interransferring ers below ty to be del
tudies carrie(series‐paraification an
14/12/2014
y challenginted above).
g the laterof these flondary layer s enhances interact on, Figure 1RI13].
al convectio
he developel the existine other hanplay a role e tank centeuce wall‐flun example osment, couointed out b
r‐layer wateenergy frothe minimuivered to th
ed out, it haallel) and thd the exerg
ng
ral ow is d. at 14
on
ed ng d, in er. id of ld by
er‐m m he
as he gy
recovery raout, heat eparameters
4. Con
Reg
atio. Again, exchangers s.
nclusions
garding the e
The coobetweefor ECOinsulatethe extr
The infwallparthe conbypass
The fullcool‐docycles sto that store isphase. Tbetter t
In the lstore sembeddexchangone heaavailablfound. Twhich ttherma
As obseduring temperstoragetemperDomestrising itlevel. Fwater othat windepenmaximu
the combinconnectivi
s
efficiency (p
ol‐down tesen 80 and 90OVAT L. Theed bottom wra cost of in
fluence of trts has beenntinuity‐intethe wallpar
l cycle testsown processshould be deat the inlets that whichThus, from than under T
light of thoshould be ded heat exger is the inat source atle (at differThus, the behey will be l system as
erved in ththe discharrature of the tank wherature at thtic Hot Watts temperatrom our pooutlet tempwhich coverndently fromum to reach
nation of a sty) and a r
performanc
st showed 0%. The lowe relative iwall. If this nsulation an
the therman analysed, egrity of thisrts insulatio
have shows, charge anesigned so at of the heah can store that point oTest2 condi
ose results, devised. Foxchangers anlet of the st a single terent tempeehaviour ofinstalled, ba whole.
he test 4 rerge processhe upper laere it is exe closest poter tanks). Cture vs. theoint of viewperature ners the temm the maxih the limit in
smart heat refined con
e) of the EC
the rather west value compact of taspect is cd the cost o
l bridge cashowing sm
s joint is a ken in a seriou
wn that evennd dischargeas the optimat exchangethe energy of view the sitions.
optimum cor instanceare workingsecond one mperature ratures), thf these deviceing their e
esults, the s in series syer as heatxpected to ossible temConversely, e initial temw, here the eeded in themperature mum tempn energy sto
exchanger dtrol strateg
COVAT conc
high thermorresponds the energy considered, of energy sa
used by thmall impactey aspect tous way.
n when highe phases armum strategrs. It has toat a tempestore worki
control strate, a chargeg in series, iand so on,is used. Hohen an optices cannot efficiency lin
water outleshow a prot is extractrecover th
mperature afEcovat incr
mperature aexergetic fe Ecovat aplevel needperature on ored density
design (congy are expe
cept:
mal efficiencto ECOVATlosses is hshould be
aved for this
he polymerit on the heo avoid a th
h efficienciere importangy for achieo be borne ierature closng under Te
tegies for ce/discharge i.e. the out might be awever, if dimum for sbe fully isolnked to the
et temperaogressive deed from it.he mass ofter a certareases the eaway from focus shoulpplication, ted in the the Ecovat
y).
1
ncrete thicknected to op
cy of the deT S whereas igher throua comproms concept.
c joint betweat losses. Nermal bridg
s can be acnt. The chareving tempein mind thaser to that aest 3 condit
charging/disprocess in
let of the tan optimumfferent heauch situatiolated from tcontrol stra
ture in theecreasing, f. Ecovat is f water stoain period oenergy storethe useful d be movethat is, useparticular
t (which is d
14/12/2014
ness, coil laptimize thes
evices, beinthe largest ugh the nomise betwee
ween EcovaNeverthelesge that wou
hieved in thrge/dischargeratures closat an efficienat the chargtions behave
scharging thn which thtopmost hem cycle if ont sources aon should bthe system ategies of th
e serpentinefollowing thnot an opeored at onof time (as ed density btemperaturd to the reeful energy applicatio
desired to b
y‐se
ng is n‐en
at ss, ld
he ge se nt ge es
he he at nly re be in he
es he en ne in by re eal is n, be
Reg
garding the t
Complethe waplumes due to enterinmodellican be substitubeen dbelow 1higher Ecovat S
From thinfluencand conratio. Aheat exthe ene
From pdegradeSome aas mitimeasur
The userecoverthe othuseful tdelivereenergy.
The impbetweethe reqimportarelevandeployiof it is b
thermal stra
ex flow strulls, therma due to temjets effectg into a layisation usedcarried out uting the reone in Test1 W/mK no values relevS) and in str
he exergy ace of the chnditions in A combinatioxchangers coergy quality.
previous expe the tank ctions on thgation actires to reduc
e of inter‐lar the stratifier. This actitemperatured to the h.
portance ofen the maxiquired usefance of gettnt as in otheng useful ebelow the u
atification:
ctures like l bridges c
mperature grts caused byer at simild in the prewith the 1
eal convectits 2+3 by raimportant dvant changratification
and heat exharge/dischathe developon of a smaonnectivity).
perience, astratificatiohe design oions like thce the de‐str
ayer water‐tcation levelion allows tre level andheating nee
f Ecovat stramum storagful temperating outlet wer storage dnergy from seful tempe
mixing due aused by tradients or by the bounlar temperasent study. D‐model byive effect baising the cde‐stratificaes in both level have b
xchanger‐buarge policy (pment of thrt heat exch) and a refi
lthough onon, like coolf the heat ehe implemratification
to‐water hels within thethe cooling od heating ofeds, thus st
atification sge temperaature for eawater tempevices. In th the higheserature leve
to develophe walls ofeventual thndary layerature cannoOnly a sen
y enhancingy an increaconductivityation effectsthe exergy been detect
uffer studie(series‐parahe tank strahanger desined contro
ly qualitativl‐down andexchangers entation oeffect.
eat pumps e tank by traof the Ecovaf the uppertrongly spre
should be reature (to incach applicaperatures athese applicat temperatuel gets more
ped turbulef the heat hermal inverrs descendiot be consisitivity analg the thermaased axial dy from 0.6 s have beenperforman
ted.
s, it has beallel) and thatification agn (concretl strategy a
vely, some heat‐up cogeometry af baffles a
are consideansferring eat lower layr layers to eading the
evised depecrease storaation. If thit the highesations, the cure down toe relevance.
1
nt boundarexchangersrsion, flow eng along thdered withysis of the al conductiviffusive mixto 10 W/mn observed,nce (up to 4
een observee heat exchand the exete thicknessare expected
effects areonvective fland their coare conside
ered in Ecovenergy fromyers below tallow this etotal amou
ending on thage energy s differencst temperatcapacity of to a situatio
14/12/2014
y layers neas, convectiventrainmenhe walls an the level omixing effevity of watexing. This hamK. For rang although fo4% lower fo
ed the stronhanger desigergy recoves, coil lay‐oud to improv
e foreseen tow patternntrol, as weered possib
vat design tm one layer tthe minimuenergy to bunt of usef
he differencdensity) ane is big, thture is not athe Ecovat on when mo
ar ve ts nd of ct er, as ge or or
ng gn ry ut, ve
to ns. ell ble
to to m be ful
ce nd he as of ost
5. Ref
[ADA93] Dthe 1993 A
[ALT05] Alstratificatio
[BAN98] Wwater ther
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