Quality control of borehole heat exchanger installations - the Swiss experiences

Transcription

1 GROUND REACH HEATING AND COOLING WITH GEOTHERMAL HEAT PUMPS Airotel Stratos Vasilikos, Athens January 24, 2008 Quality control of borehole heat exchanger installations - the Swiss experiences Walter J. Eugster Polydynamics Engineering Zurich Switzerland

2 Introduction Legislation and licensing (ground water protection) Design Quality assurance of BHEs (Swiss quality label) Summary

3 Heat pump market in Switzerland Total number of HPs installed in 2006: Total number of HPs installed in Switzerland: ~112'000 Total number of GSHP installations: ~ 42'000 '82 '84 '88 '90 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06

4 Borehole heat exchanger market in Switzerland '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 new retrofit total Total number of meters drilled for BHEs per year

5 Swiss quality label for drilling companies

6 Introduction Ground water protection and legislation Design Quality assurance of BHEs (Swiss quality label) Summary

7 Legislation: Water protection law of January, 24, 1991 due diligence for every one it's forbidden to pollute ground-water it's forbidden to connect different ground water storeys every drill hole in a ground-water protection area needs a licence

8 Licensing: Every BHE installation needs a license (applied for in advance) by the ground-water protection authority BHE's are strictly prohibited in inner ground-water protection zones (near water well) are licensed in all unprotected areas could be licensed in outer protection areas

9 Licensing (suite): BHEs are not allowed in e.g. karstic areas areas with possible geogenic impacts known contaminated sites BHE's could get a license under special conditions in areas with e.g. different ground-water storeys artesian ground-water strongly mineralized water

10 Licensing (suite): Licensing authorities prepare BHE license maps (mainly web- based GIS applications) with indication at which location BHEs: are allowed are allowed under special conditions are not allowed

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12 Standard licensing conditions (examples): announce the start of drilling work to authority announce all incidents that are relevant to ground-water and environment protection dispose drilling mud and fluids correctly BHEs have to be pre-fabricated and tested in factory BHEs are backfilled diligently and densely from the bottom to the top perform a pressure and flow test (SN EN 805) fill in a drilling and a testing record and send to authority

13 Standard licensing conditions (suite): only use heat carrier fluids without any threat to ground-water install a leakage alarm system Special licensing conditions (e.g.) monitoring/supervision of drill work by a geologist limitation of BHE length permanent casing

14 Introduction Legislation and licensing (ground water protection) Design Quality assurance of BHEs (Swiss quality label) Summary

15 A correct dimensioning of BHEs assures a problem-free operation over the entire life cycle takes into account the real local conditions real petrophysical conditions e.g. thermal conductivity real climatic conditions e.g. temperature, operation time real operation conditions e.g. DHW, swimming pool, heating & cooling takes into account the real geometry of the BHE diameter 32, 40 or 50mm tubes distance between BHEs,, depth of BHEs layout (line, rectangle etc.)

16 Dimensionierung Consequences for simple installations no longer use the old-fashioned rules-of of-thumbs W/m dimension the BHEs according to SIA 384/6 release in 2008 BHEs dimensioned according to SIA 384/6 are a little bit longer than before

17 spez. Leistung pro Meter EWS. Example SIA 384/ W/m W/m W/m W/m W/m How to dimension the length of a BHE for a small installation? 2900 h Next step: define additional length of the BHE for yearly 2700 h operation time in function of 2500 h the BHE layout Norm-Jahresbetriebsstunden W/m 70.0% 2300 h spez. Leistung bei 1.5 MJ/m³ First step: define base spez. Leistung bei 2 MJ/m³ W/m 60.0% 1 EWS spez. Leistung bei 2.5 MJ/m³ W/m 2100 h 2 EWS 5m 3 EWS 5m 50.0% of thermal 4 EWS 5m conductivity 1900 h 2 x 2 EWS 5m W/m 1.0 W/mK 1.5 W/mK 40.0% 2.0 W/mK 2.5 W/mK 3.0 W/mK 3.5 W/mK 4.0 W/mK 1700 h Wärmeleitfähigkeit Zuschlag in %. 30.0% extraction rate in function Next step: define standard yearly operation time in function of the height above sea level 1500 h 0 m 200 m 400 m 600 m 800 m 1000 m 1200 m 1400 m 1600 m 1800 m 2000 m 20.0% Höhe über Meer Alpennordseite 10.0% 0.0% Betriebsstunden pro Jahr

18 Introduction Legislation and licensing (ground water protection) Design Quality assurance of BHEs (Swiss quality label) Summary

19 Quality control by client/owner commission only experienced planner or installer order a heat pump with quality label commission a drilling company with quality label ask for references But: the personal experience and knowledge of each involved professional is essential

20 Quality control during drilling work Drilling company with quality label verified quality broad consulting of the owner by the drilling company clear communication of drilling risks and possible insurances yearly professional training of drilling staff yearly inspection of drilling staff on site technical coaching of drilling company drilling work conform with rules of ground-water and environment protection accurate intervention with a gaz / artesian water incident certified material and certified drilling work

21 Quality control during drilling work no drilling without license accurate drilling equipment for local conditions trained drilling staff state-of of-the-art drilling technique first intervention equipment on site complete backfilling equipment on site preventer or dense casing head

22 Quality control during drilling work drilling record is prepared proper disposal of drilling mud/water clean drilling site check of the BHE before installation fix injection tube at the bottom of BHE careful and slow mounting of BHE instantaneous backfilling of BHE

23 Quality control during drilling work pull casing after backfilling flow and pressure testing according to SN EN 805 mark and protect visible BHE tubes hand out a complete documentation

24 Qualitätssicherung tssicherung Risks when drilling BHEs the landowner carries the risk of the underground the client carries the additional costs, induced by repair of a gas or artesian water incident drilling into karstic formations, ground-water layers, contaminated sites all incidents relevant for ground-water and environment protection drilling into special geological formations It is highly recommended to effect an insurance which covers these risks.

25 Introduction Legislation and licensing (ground water protection) Design Quality assurance of BHEs (Swiss quality label) Summary

26 Summary each BHE needs a license (ground-water protection authority) the authority may impose special conditions commissioning of experienced professionals with a certain base knowledge (look for quality labels) correct dimensioning of the BHEs (SIA 384/6) insurances to cover the owners risks immediate grouting of the BHEs from the bottom to the top flow and pressure testing according to SN EN 805 with accurate test records

27 Thank you The Swiss quality control programme is financed and supported by: SFOE FOEN