EXPERIMENTAL STUDY OF ACTIVE SOLAR THERMAL COLLECTORS INTEGRATED IN BUILDING FAÇADE

Transcription

1 EXPERIMENTAL STUDY OF ACTIVE SOLAR THERMAL COLLECTORS INTEGRATED IN BUILDING FAÇADE Talal Salm Building Scincs Laboratory, ENTPE Ru Mauric Audin Vaulx-n-Vlin 69120, Franc Pirr Michl Building Scincs Laboratory, ENTPE Ru Mauric Audin Vaulx-n-Vlin 69120, Franc ABSTRACT This papr rports on th scond stag of a study conductd within th framwork of a rsarch and dvlopmnt projct. Th projct aims at studying, dsigning and ralizing a structural componnt of building nsuring in a prmannt and intgratd way th st of functions normally providd by lmnts of façad and by thrmal liquid-coold collctors. Th product is intndd to b distributd and implmntd by building profssionals. Prototyp activ thrmal solar collctors wr intgratd in th façad of a ral-siz building nar Lyon in Franc. A computr basd ral tim monitoring systm has bn installd to masur th thrmal prformanc of th systm and xprimntal tsts ar conductd. Th aim of th currnt xprimntal study is to valuat th nrgy prformanc of th componnt and to study th impact of solar intgration on th building intrnal nvironmnt. Th papr rsums th arly rsults from th first stag of th xprimntal study. Thn it prsnts th xprimntal installation with th prototyp façad lmnts. Aftrwards, it dtails th xprimntal approach and prsnts th mountd data acquisition systm usd during th xprimntal tsts. Finally it summarizs th xprimntal rsults obtaind so far. 1. INTRODUCTION During th past thirty yars, solar thrmal quipmnts hav bn subjct to many nhancmnts, but thir us in buildings is still rstraind by four major strongly dpndnt constraints: Th quality of thir intgration into th building architctur and nvironmnt; Th asthtics prcption of th solar systm within th building; Th cost of th installation and its implmntation in comparison to traditional convntional systms; Th fact that thir distribution is limitd to som spcific circuits distinct from th building traditional sctor. Thus, intgration of activ solar thrmal componnts into th building structur must b a major concrn for th yars to com in ordr to avoid unasthtic installation solutions and significant ralization ovr costs. Buildings intgratd collctors hav many advantags ovr convntional collction systms including th possibility of xpanding to covr th ntir ara of th roof at a rasonabl cost and that ths systms usually hav a longr srvic lif, which rsults in lss rplacmnt of matrials and mor consrvation 0. In ordr to rcovr th maximum of solar nrgy, th solar thrmal collctors ar frquntly installd undr optimal conditions rgardlss to th quality of thir intgration 0 0. Most oftn thy ar considrd as tchnical

2 2 SOLAR BUILDINGS 333 lmnts and ar confind to th roof top whr a bad intgration is lss visibl and has a minor impact 0. In mid-latituds, th solar radiation on vrtical collctors is rducd by 30% 0 but it is bttr distributd ovr th yar in comparison to solar radiation on tiltd collctors (Fig. 1). kwh/m² pr day 6,0 5,0 4,0 3,0 2,0 1,0 0,0 2,5 2,2 4,5 2,5 Jan Fb Mar Apr May Jun Jul Aug Sp Oct Nov Dc α 5,2 3,1 Tiltd Surfac 45 Vrtical Surfac 90 Fig. 1: Yarly distribution of th solar irradiation on vrtical vrsus 45 tiltd surfacs (Lyon, lat.). This rlativly uniform profil for th façad collctor can hlp prvnting ovrhating risks in summr and maks it asir to dimnsion th systm according to th hat dmand. In this contxt, th work on th dvlopmnt of a solar componnt for façad intgration has bn carrid out within a R&D projct. Th dsign of th componnt was basd on lightwight façads (Fig. 2). 2. BACKGROUND AND EARLY RESULTS Th first stag of th xprimnt was conductd during th scond smstr of It consistd of studying th dsignd prototyp and invstigating th us of colourd absorbrs for ths lmnts. Thus, thr prototyps collctors having 1.9 m² collcting ara ach wr intgratd in th façad of xprimntal building and wr linkd sparatly to a SDHW systm. Th absorbrs of th prototyps wr mad of coppr and coatd with thr diffrnt colours: slctiv black coating, RAL (Gry) and RAL 6009 (Grn). Colourd absorbrs hav shown a slight infrior thrmal prformanc compard to slctiv colour coatings. But th dcras in th nrgy prformanc du to th colour tratmnt of th absorbrs, and th non-optimal positioning of th componnts can b balancd with a bttr architctural intgration and a modrat ovr cost 0. Th dvlopmnt of slctiv colours for absorbrs appars as an ssntial stp in ordr to construct visually attractiv systms with thrmal prformancs idntical to typical absorbr coatings. Colourd absorbrs offr to architcts nw possibilitis and advantags for using thrmal façad solar collctors 0. This will hlp in a broad dissmination of solar thrmal systms. Filds of application can b sn in nwly constructd houss as wll as in rtrofits. Th xprimnt prmittd to tst th functioning and th bhaviour of prototyp solar componnts units in tim undr ordinary and stagnation conditions. Th scond stag aims at studying xprimntally th bhaviour of an array of intgratd collctors and th impact of th intgration in façads on th intrnal nvironmnt of th building. 3. EXPERIMENTAL SETUP AND PROCEDURE Fig. 2: Prototyp solar façad componnt dsign. By varying th surfac grid dimnsions, th kind and colour of th covr strip and th colour of th absorbr th look of th façad can b changd. On th basis of th dsign concpt, prototyp façad collctors wr assmbld and installd in th south-wst orintd façad (az = 45 ) of Grands Atlirs building locatd in Isl d Abau nar Lyon for xprimntal tsting in ral conditions. An xprimntal cll with controlld nvironmnt was mountd bhind th collctors in ordr to 1 RAL is a Colour Rfrnc Systm that was invntd in 1927 by Richsausschuss für Lifrbdingungn in Grmany

3 334 Procdings of ISES Solar World Congrss 2007: Solar Enrgy and Human Sttlmnt study th volution of th indoor nvironmnt du to th façad collctors. 3.1 Th Exprimntal Solar Thrmal Systm Th collcting systm consists of nin façad collctors and thr transparnt glazd lmnts (Fig. 3). Each collctor has 1.9 m² collcting ara. Non-slctiv black coatd aluminium absorbrs ar usd for this stag of th xprimnt instad of coppr absorbrs for asthtical rason. Two systms for production of hot watr wr thn installd. Th first systm has a storag tank of 150L and is connctd to th thr collctors undr th glazd part. Th scond systm has a storag tank of 300L and is connctd to th six othr collctors. Rgulation units, pumps and xpansion tanks ar installd for both systms. Th glazd part includs 3 windows with tripl glazing (6/63/6/16/6). All ar quippd with automatd black Vntian blinds. A magntic flow mtr to masur th mass flow of th primary hat-transfr fluid of th six collctors systm. 3.2 Th Exprimntal Cll An xprimntal cll with controlld nvironmnt was installd bhind th façad moduls. Th cll has a volum of 40 m 3 and consists of rigid polyurthan foam panls (thicknss = 80 mm, R = 3.45 m².k.w -1 ). Th cll has an intrnal modular partition panls (thicknss = 60 mm, R = 2.05 m².k.w -1 ) in ordr to crat diffrnt zons bhind th collctors (Fig. 4). An air-conditioning machin was installd to control th tmpratur of th room. Fig. 4: Dimnsions of th xprimntal cll. 6 collctors 3 glazd lmnts (connctd to 300L 3 collctors storag tank) (connctd to 150L storag tank) Fig. 3: Prototyp façad collctors installd on sit. According to th tst mthods of NF EN , a numbr of snsors wr installd on th solar systms: Nin surfac probs of typ Pt 100 at th back surfac of th prototyps absorbrs to masur th tmpratur of th aluminium plats; Four probs of typ Pt 100 in th primary fluid pips to masur th tmpraturs of th hat-transfr fluid at th inlt and th outlt of th componnts; Six probs of typ Pt 100 installd in th storag tanks (thr for ach tank) at diffrnt lvls to masur th watr tmpratur; Two lctrically opratd flow control valvs in ordr to control watr dmand scnarios; Th following probs wr chosn and installd according to NF EN ISO : Thirtn surfac probs of typ Pt 100 installd on th intrnal walls of th cll; Thr probs of typ Pt 100 installd outsid th cll to masur th boundary condition tmpraturs; Two snsor-transmittrs of tmpratur and rlativ humidity installd insid th xprimntal cll; Two probs of typ Pt 100 at th air flow input and output of th air-conditioning machin; On air spd transmittr installd at th output of th air-conditioning machin. 3.3 Th Acquisition Systm In ordr to raliz th acquisition on computr of th various data transmittd from th probs, it was ncssary to install spcific acquisition moduls. Thrfor, svn tmpratur acquisition moduls (rsolution=0.1) allowing acquisition of 42 tmpraturs signals and a modul with 8 analogical ntris 4-20mA allowing th acquisition of th ambint tmpratur, th rlativ humidity and th flow

4 2 SOLAR BUILDINGS 335 signals wr installd. A modul with 8 digital outputs allowing th control of th lctrical valvs was st thraftr. Ths moduls ar quippd with connction RS 485, whil th computr has a connction RS 232. A signal convrtr RS 485/RS 232 was installd on th port sris of th computr to assur th communication btwn th moduls and th computr. Industrial Automation OPC Srvrs softwar has prmittd to configur ths moduls and to crat a computr/moduls intrfac. Th Modbus protocol is usd for this communication. LabVIEW 7.1 was usd to dvlop a usr frindly intrfac for th data monitoring systm to control th installation and to sav data. Th Pt 100 probs usd for th xprimnt ar manufacturd according to th Norm IEC 751, class B. Thus, by calculating th budgt of uncrtainty 0, th accuracy of th masurmnts is prsntd in th following tabl: TABLE 1: ACCURACY OF MEASUREMENTS Prob Modul Accuracy Pt 100 probs (absorbrs) ± 0.9 C ± 0.3 C ± 1.2 C Pt 100 (Othrs) ± 0.7 C ± 0.3 C ±1 C T transmittr ± 0.2 C ± 0.2 C ±0.4 C HR transmittr ± 2.0 % ± 0.2 % ±2.2% Flow mtr ± 0.2% mas. ± 0.2% mas. A mtorological station installd on th building by th Building Scincs Laboratory of ENTPE givs th ral tim climatic paramtrs such as solar radiations, ambint tmpratur, rlativ humidity and wind spd. A rmot control systm was stup in ordr to tak control of th installation dirctly from th Laboratory, for a bttr follow-up of data acquisition and a daily vrification of th functioning of th systm. - working of th acquisition systm and to locat dfctiv probs. Thn a scond sris was don btwn 9 th and 14 th of Jun undr good masurmnt conditions. Indd, in this priod, th global horizontal radiation has xcdd 900 W/m² in th first and th last two days and th avrag ambint tmpratur was qual to 21.8 C. During this masurmnt priod, collctors undr stagnation conditions wr tstd. Th air-conditioning machin was not functioning yt. Th figur 5 illustrats th avrag tmpraturs of th absorbrs and th back surfacs of th intgratd collctors. Th objctiv of this illustration is to invstigat th impact of th tmpratur of th absorbr whn th collctor is undr critical conditions (stagnation) on th back tmpratur of th collctors, accssibl to potntial usrs. Thus w can vrify th scurity of th us of such componnts against any burn risk ) C ( 60 r t u a r p 40 m T /6/07 0:00 10/6/07 0:00 11/6/07 0:00 12/6/07 0:00 13/6/07 0:00 14/6/07 0:00 Man Tsa Man Tsi Fig. 5: Avrag tmpratur of th absorbrs and avrag tmpratur of th back surfac of th collctors. Th avrag tmpratur of th absorbrs rachd 95.1 C in th first day whn th maximum horizontal global solar radiation was qual to 958 W/m² and th maximum outdoor ambint tmpratur was 31.1 C. Th tmpratur of th indoor surfac of th collctor didn t xcd 41.7 C with a diffrnc of 53.4 C. This suggsts that th back surfac of th intgratd collctor is wll protctd from ovrhating risks. 4. ANALYSIS OF FIRST RESULTS A first sris of masurmnts was conductd btwn 29 th of May and 5 th of Jun It nabld us to vrify th 5. CONCLUSION AND PERSPECTIVES An xprimntal work has bn conductd to study th prformanc of prototyp façad thrmal collctors and thir impact on indoor nvironmnt. Th rsults from th

5 336 Procdings of ISES Solar World Congrss 2007: Solar Enrgy and Human Sttlmnt first stag of th projct showd that th us of ths prototyps in buildings and th us of colourd absorbrs in ths componnts can b sriously considrd for a nw fild of application for solar thrmal systms. In th scond stag, an array of nin collctors and an xprimntal cll installd bhind th collctors wr studid. A first sris of masurmnts nabld us to validat th acquisition systm and thrfor liminat all sourcs of rrors. A scond sris of masurmnts prmittd to invstigat th volution in th tmpratur of ths componnts undr stagnation conditions and to vrify on aspct in th scurity of thir us. In th continuity of this work, svral sris of masurmnts ar programmd according to a prdfind xprimntal protocol. Th xprimntal installation will b usd to invstigat th impact of th hydraulic schm on th solar systm yild. Finally it will b usd to masur and xamin th volution of th indoor tmpratur and to highlight th influnc of th prsnc of th intgratd collctors on th indoor nvironmnt. 6. ACKNOWLEDGMENTS Th work on which this papr is basd was fundd by th Frnch Agncy for Environmnt and Enrgy Managmnt (ADEME). Th authors would lik to thank thir partnrs in th projct, Alain Filloux (Alphis), D. Villir (Giordano), Sonia Cortss (A&D), M. Olivir (Grands Atlirs), C. Midlt and J. Maquin (AS Tchnal). 7. REFERENCES (2) MM. Hassan, Y. Blivau, Modling of an intgratd solar systm, Building and Environmnt (2007), doi: /j.buildnv (3) W. Wiss and I. Stadlr, Facad intgration a nw and promising opportunity for thrmal solar collctors. Industry Workshop, IEA-SHC Task 26, (4) T. Salm, P. Michl, Intgration of activ thrmal solar componnts in facad lmnts, Cisbat 2005 Procdings, Lausann, Switzrland, pp (5) M. Munari Probst, C. Rockr, Towards an improvd architctural quality of building intgratd solar thrmal systms, Solar Enrgy (2007), doi: /j.solnr (6) T. Matuska, B. Sourk, Façad Solar Collctors, Solar Enrgy 80 (2006), pp (7) T. Salm, P. Michl, Intgration of Activ Solar Thrmal Collctors with Colourd Absorbrs in Façads, Epic 2006 Procdings, Lyon, Franc, pp (8) T. Müllr, W. Wagnr, Colourfac - Colourd collctor facads for solar hating systms and building insulation, Eurosun 2004 Procdings, Friburg, Grmany, pp (9) Asch G., Acquisition ds donnés : du captur à l ordinatur, Dunod, Paris, 2003, p (10) Afnor, Thrmal solar systms and componnts - Factory mad systms-tst mthods, pren , p 54. (11) Afnor, Ergonomics of th thrmal nvironmnt Instrumnts for masuring physical quantitis, NF EN ISO 7726, 2001, p.69. (1) T. Salm, Intgration of Solar Thrmal Componnts in th Building Structur, INSA-Lyon, January 2007, p. 397.