Efficient heating and cooling with borehole heat exchangers

88 ACC JOURNAL 2019, Volume 25, Issue 1 DOI: 10.15240/ ul/004/2019-1-008 EFFICIENT HEATING AND COOLING WITH BOREHOLE HEAT EXCHANGERS Axel Ge schel1; Ma kus Haack2; P asan h Sub amani; Lukas S öckmann; Thomas Schä e ; Tom Wal e ; Tino Schü e; Jö n K immling Hochschule Zi au/Gö li z, Uni e si y o Applied Sciences, Fakul ä Wi scha swissenscha en und Wi scha singenieu wesen, Theodo -Kö ne -Allee 16, 02763, Zi au, Ge many e-mail: 1axel.ge sc[email p o ec ed]; [email protected] Abs ac G ound-sou ce hea pumps a e a sus ainable echnology o inc ease he use o enewable ene gy sou ces. In o de o exploi he maximum po en ial o nea -su ace geo he mal ene gy, op imiza ion concep s o bo ehole hea exchange sys ems ha combine hea ing and cooling a e being de eloped a he Uni e si y o Applied Sciences Zi au/Gö li z. The objec i es o his esea ch a e no only he educ ion o p ima y ene gy consump ion bu also he de elopmen o p edic i e models o sys em planning, especially wi h espec o he in luence o g oundwa e . Addi ionally, cons uc i e and economic aspec s o bo ehole hea exchange sys ems a e e alua ed. Keywo ds Nea -su ace geo he mal ene gy; Hea pump; Bo ehole hea exchange ; Renewable ene gy; Seasonal he mal ene gy s o age; G oundwa e low. In oduc ion The use o nea -su ace geo he mal ene gy o hea ing and cooling o buildings is an e icien al e na i e o con en ional sys ems. U ilizing geological subsoil as a hea sou ce and sink p o ides la ge po en ial o sa ing p ima y ene gy. By his, i helps o achie e ambi ious ene gy ansi ion a ge s [1]. Toge he wi h panel hea ing and cooling sys ems, geo he mal p obes a e pa icula ly sui able as unde g ound hea exchange s. G ound-sou ce hea pump (GSHP) sys ems can un old hei maximum pe o mance capabili ies by using subsoil as he mal s o age and in case o combined hea ing and cooling applica ions. Fo his pu pose u he esea ch on planning me hods, p edic ion models and p ac ical ope a ional concep s a e essen ial. The e o e, an in e disciplina y junio esea ch g oup a Zi au/Gö li z Uni e si y o Applied Sciences was es ablished. This g oup consis s o esea che s specialized in he ields o applied ma hema ics, enginee ing, geosciences and economics. 1 Op imiza ion Issues o Geo he mal Ene gy Sys ems The main opic o esea ch deals wi h geo he mal ene gy supply concep s o non- esiden ial buildings. In addi ion o co e ing hea ing demand, he ene gy supply sys ems in hese buildings mo e and mo e o en ha e o co e cons uc ion and usage- ela ed cooling demand. Howe e , complex ene gy demand s uc u es lead in planning p ac ice o en o unce ain ies in he design o bo ehole hea exchange (BHE) ields [2]. The e o e, he op imal u iliza ion o na u al egene a ion and ene gy s o age e ec s o he subsoil equi es he de elopmen o new app oaches in he cons uc i e design o he BHE ield and he BHE i sel . Associa ed p oblems ha e o be in es iga ed h ough pa ame e s udies wi h he aid o high- esolu ion nume ical building and sys em simula ion models. The aim is o sys ema ize he decision- 89 making p ocess o an op imal sys em con igu a ion (building and i s en i e echnical equipmen ) by model-based op imiza ion and e alua ion o mul idimensional e iciency c i e ia. Addi ional aspec s a e he assessmen o planning models wi h espec o hei p edic ion accu acy and he e alua ion o o e as well as unde dimensioning e ec s in he cons uc i e design o BHEs. 2 The In luence o Geology and G oundwa e The hea anspo and possible he mal s o age in he subsoil a ies conside ably, depending on local geological and hyd ogeological condi ions. Hence, he in luence o he p e ailing geology and g oundwa e si ua ion in associa ion wi h he usage o nea -su ace geo he mal ene gy is ano he key opic o his esea ch p ojec . De ailed knowledge o he he mal p ope ies o he subsoil is essen ial o a p o ound design o BHE sys ems. In his con ex , he he mal conduc i i y and hea capaci y o he ock laye s as well as na u al unde g ound empe a u e belong o he mos impo an p ope ies ha a e highly loca ion-dependen . Un o una ely, hyd ogeological ac o s, especially con ec i e hea anspo induced by g oundwa e low, a e o en neglec ed du ing sys em dimensioning. The eason o his is ha cu en ly no well-enginee ed applica ion-o ien ed planning guide exis s o his speci ic p oblem. In addi ion, gene a ion o cos ly and ime-consuming nume ical g oundwa e low models a e o en no jus i ied in planning p ac ice [3, 4]. Howe e , especially when he geological subsoil is used as a seasonal he mal s o age by combined hea ing and cooling applica ions, he g oundwa e low induces con ec ion ha in luences he sys em pe o mance nega i ely. The igno ance o g oundwa e low may lead o unde dimensioning o BHE ields. Con a y o ha , g oundwa e low can inc ease he pe o mance o solo hea ing applica ions. The u iliza ion o he subsoil ock o he mal s o age can inc ease he e iciency o g ound-sou ce hea pump sys ems. The e o e, conside a ions o hyd ogeological ac o s in he de elopmen o planning and design ools a e ine i able. The abo e-men ioned ques ions a e being answe ed wi hin he amewo k o he mo- hyd aulic modelling a Zi au/Gö li z Uni e si y o Applied Sciences. The pe meabili y coe icien (k - alue) and he e ec i e po osi y o ele an ock laye s as well as he hyd aulic g adien o g oundwa e belong o he hyd aulic aqui e p ope ies in he cen e o a ac ion [3]. These hyd ogeological pa ame e s ha e o be sys ema ized wi h espec o hei in luence on he hea anspo and i s consequences o he o e all sys em dimensioning. Based on his, simpli ica ions can be de i ed o pe spec i e de elopmen s o new app oaches in dimensioning o BHE ields. 3 BHE Tes Bench o Expe imen al In es iga ions In o de o alida e he model h ough expe imen al in es iga ion a es bench equipped wi h ex ensi e measu emen echnology is a ailable (Fig. 1). The sys em consis s o h ee BHEs o ype PE-Xa 32 mm double-U wi h di e en dep hs a anged in iangula o m. Hea ing ope a ion can be ealized by means o a buil -in comp ession chille . On he o he hand, simula ion o he cooling ope a ion, as well as eeding o sola he mal ene gy, can be ealized wi h he help o a gas-condensing boile . All main componen s as well as in eg a ed he mal bu e s o age a e connec ed o each o he ia a comp ehensi e hyd aulic sys em (Fig. 2). All BHEs, including he con ol p obe a he cen e, ha e a ull-leng h ieldbus senso sys em o measu e he empe a u e e e y me e in dep h. The sys em design allows ope a ions o single o mul iple BHEs wi h indi idually adjus able low a es and de ined hea ing o cooling powe (hea ing powe : max. 132 kW, cooling powe : max. 45 kW, ci cula ion pump: max. 12.6 m3/h). The ope a ing ange o he es bench 90 goes om -10 °C o +90 °C in o de o map ope a ing poin s o comme cially a ailable hea pump sys ems adequa ely. In addi ion o sophis ica ed model alida ion, he es bench is used o de e mining he loca ion-dependen s o age u iliza ion a e depending on bo ehole dep h [5]. By doing so, he in luence o g oundwa e con ec ion on he mal s o age p ocess can also be analysed. 4 Cons uc i e Issues o BHEs The analysis o cons uc i e and ma e ial- echnical issues o BHEs ep esen s ano he impo an opic. He e, mechanically, he mally and chemically induced damages on geo he mal p obes a e unde in es iga ion. BHE ins alla ion mis akes a e a equen cause o mechanical damage. S uc u al damage in he g ou ma e ial caused by in ensi e and apid os - haw cycles is one o he easons o he mally induced damage. As a possible consequence, undesi ed annula gaps be ween g ou and p obe may o m. I a damaged segmen o bo ehole back illing is loca ed in he dep h o aqui e s, his is c i ical wi h ega d o he sys em igh ness, demanded by he au ho i ies. The same is ue in case o chemical decomposi ions o he g ou caused by unsui able ma e ials in co osi e unde g ound condi ions. Wi hou he p esence o g oundwa e , he ca i ies o de ec s wi hin he g ou ac as a he mal insula ion, which leads o a educ ion in he BHE pe o mance. The e o e, he objec i es o esea ch a e o analyze possible damages caused by means o mul iphysical simula ions and o de i e ecommenda ions o educ ion o isk o damage. Fig. 1: Tes bench ( om le o igh ): gas- condensing boile , comp ession chille , he mal s o age Fig. 2: Sys em scheme Conclusion The junio esea ch g oup in he ESF- unded esea ch p ojec „The mal s o age p ocess a ound bo ehole hea exchange o hea ing and cooling o buildings wi h hea pumps“ p o ides he oppo uni y o examine he complex opics o nea -su ace geo he mal ene gy in mul idisciplina y manne a Zi au/Gö li z Uni e si y o Applied Sciences. Wi h e e ence o he inc easing demand o ene gy supply in buildings using hea pumps, an applica ion- o ien ed con ibu ion o he planning p ac ice can be ealized. Acknowledgmen The Eu opean Union and F ee S a e o Saxony und he desc ibed esea ch p ojec . Fo p o essional ad ice, many hanks also go o P o . D . Jens Meine . 91 Li e a u e [1] BUNDESMINISTERIUM FÜR WIRTSCHAFT UND ENERGIE (2015): Ene giee izienzs a egie Gebäude. B ochu e. 146 pp. Be lin. [2] BAYER, P.; de PALY, M.; BECK, M. (2014): S a egic op imiza ion o bo ehole hea exchange ield o seasonal geo he mal hea ing and cooling. Applied Ene gy. Vol. 136, pp. 445–453. DOI: 10.1016/j.apene gy.2014.09.029 [3] KÖLBEL, T. (2010): G undwasse ein luss au E dwä mesonden: Geländeun e suchungen und Modell echnungen. Disse a ion. 146 pp. Ka ls uhe Ins i u e o Technology. [4] BAUER, D. (2011): Zu he mischen Modellie ung on E dwä mesonden und E dsonden-Wä mespeiche n. Disse a ion. 121 pp. Uni e si y o S u ga . [5] KRIMMLING, J. e al. (2015): Speiche o gänge im Um eld e ikale E dsonden on Wä mepumpen. HLH. Vol. 66 (1): 19 pp. Axel Ge schel; Ma kus Haack; P asan h Sub amani; Lukas S öckmann; Thomas Schä e ; Tom Wal e ; Tino Schü e; Jö n K immling 92 EFEKTIVNÍ KONCEPTY NA TOPENÍ A CHLAZENÍ POMOCÍ GEOTERMÁLNÍCH SOND Na pozadí s ano ení ene ge icko-poli ických cílů předs a ují epelná če padla spojená se zemí slibnou echnologii na zásobo ání budo e mickou ene gií. Na odk y í ne yuží aných po enciálů po chní geo e mii jsou p o o na Vysoké škole Zi au/Gö li z y íjeny op imalizační koncep y na zařízení geo e málních sond kombino aném opném a chladícím p o ozu. Hla ni zaměření ýzkumu náleží úspoře p imá ní ene gie, jakož i zlepšení p edik i ních modelů p o ná h zařízení, z láš ě s ohledem na li podzemních od. Předmě em s udie jsou aké kons ukční a ekonomické aspek y sys émů geo e málních sond. EFFIZIENTE HEIZ- UND KÜHLKONZEPTE MIT ERDWÄRMESONDEN Vo dem Hin e g und ene giepoli ische Ziels ellungen [1] sind e dgekoppel e Wä mepumpen eine zukun s ähige Technologie ü die he mische Gebäudeene gie e so gung. Zu E schließung on ungenu z en Po enzialen in de obe lächennahen Geo he mie we den dahe an de Hochschule Zi au/Gö li z Op imie ungskonzep e ü E dwä mesondenanlagen im kombinie en Heiz- und Kühlbe ieb en wickel . Hie bei s eh die Einspa ung on P imä ene gie ebenso wie die Ve besse ung on Vo he sagemodellen zu Anlagenauslegung, insbesonde e un e Be ücksich igung on G undwasse ein luss, im Fokus de Fo schung. Un e suchungsgegens and sind da übe hinaus kons uk i e und wi scha liche Aspek e on E dwä mesondenanlagen. EFEKTYWNE KONCEPCJE OGRZEWANIA I CHŁODZENIA PRZY POMOCY SOND GEOTERMALNYCH W odniesieniu do celów ok eślonych w zak esie poli yki ene ge ycznej pompy cieplne połączone z ziemią s anowią obiecującą echnologię służącą do zasilania budynków ene gią cieplną. W celu zbadania niewyko zys anego po encjału geo e mii powie zchniowej w Szkole Wyższej Zi au/Gö li z op acowywane są koncepcje op ymalizujące u ządzenia sond geo e malnych p acujących w ybie og zewania i chłodzenia. Badania skupiają się głównie na oszczędności ene gii pie wo nej a akże udoskonaleniu modeli p ognos ycznych w celu zap ojek owania u ządzeń, ze szczególnym uwzględnieniem wpływu wód podziemnych. P zedmio em badań są akże aspek y kons ukcyjne i ekonomiczne sys emów sond geo e malnych.