Geothermal Respose Test Border Conditions Measurements at IAG Test Site Darmstadt, Willich Technical University of Darmstadt

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1 Geothermal Respose Test Border Conditions Measurements at IAG Test Site Darmstadt, Willich Technical University of Darmstadt Clemens Lehr Clemens Lehr 1

2 Geotechnik Lehr Development of Measuring Tools and Measuring Service: Geothermal Response Test (GRT, egrt) Fiber Optical Systems: Distributed Temperature Sensing (egrt),strain, Pressure, Accelerometer Grout Control Digital Recording of Flow, Density and Pressure while Grouting Flow Rate and Yielding Resistance Test, Pressure and Tightness Test on Borehole Heat Exchanger Temperature Depth Profiles, Groundwater Detection, Grout Survey Ultra Slim Probes BHE Logs - Susceptibility, Deviation, Temperature, Depth Survey Dimensioning of BHE Arrays and Heat Pump Systems Technical Equipment for Engineers and Designers, Courses of Instruction Software Development TRT 2.0 Software for Evaluation of Geothermal Response Test and Enhanced Geothermal Response Test Data. SF numerical Software for Dimensioning and hydro-thermical Simulations. EA Geothermie The Geothermal Energy Study Group was set up in Bochum in 2004 and became the joint DGGV/DGGT study group in Some 20 specialists from universities, authorities and engineering consultants are active in the group and meet two or three times a year. Lecturer at Technical University of Darmstadt (Institute of Applied Geosciences) Member of German Geothermal Society, German Heating Pump Society, International Geothermal Society (IAG) Clemens Lehr 2

3 Overview former Investigations Clemens Lehr 3

4 Test Site Darmstadt Clemens Lehr 4

5 Quaternary B 2 Granodiorite Weathering Zone Hybrid Cable Hybrid Cable BHE Grout Granodiorite Granular Desintegration Zone Clemens Lehr 5

6 Depth [m] GRT Workshop Prague Labortory Tests Drilling Core B2 Thermal Conductivity Density (dry) Porosity dry saturated Clemens Lehr 6

7 Air Temperature [ C] Effective Thermal Conductivity [W / (mk)] GRT Workshop Prague Date Time Power GRT Duplex-U-BHE Moving Avarage 7 Days GRT Coaxial- BHE January 2009 July 2009 January 2010 July 2010 January 2011 July Clemens Lehr 7

8 Air Temperature [ C] Effective Thermal Conductivity [W / (mk)] GRT Workshop Prague Date Time Power Moving Avarage 7 Days EGRT Duplex-U- BHE EGRT Coaxial- BHE July 2010 January 2011 July 2011 January 2012 July Clemens Lehr 8

9 Measurements in Different Measurement Devices at B 2 6 Different Evaluation Methods: Evaluation by Device owning Company/ Institution Evaluation via TRT 2.0 Software: Line Source Averaged Heating Power Line Source Variable Power/ Superposition Cylinder Source Averaged Heating Power Cylinder Source Variable Power/ Superposition Clemens Lehr 9

10 TEST SITE WILLICH On the Test Site Willich various Configurations and Combinations of Borehole Heat Exchangers and Heat Pumps will be examined. In a first Step the thermo-physical Environment will be determined. Thereafter different Combinations of BHE Types and Heat Pumps under realistic operation Conditions will be investigated. As a Result Temperature Behavior and Efficiency of the Settings are analyzed. Comparison of various Borehole Heat Exchanger Types and Grouting 3 Duplex-U-BHE 32 mm, 30 m 3 Coaxial-BHE Ø 140 mm (Heat-Storage-BHE), 30 m 3 Single-U-BHE 40 mm, 30 m Each Type of BHE were completed with 3 Kinds of Grouting Materials: Simple Grouting (λ 1,2 W/(mK)) Enhanced Grouting (λ 2,0 W/(mK)) Clay Pellets (λ 1,2 W/(mK)) Clemens Lehr 10

11 Each BHE is equipped with Flowmeter and Temperature Sensors. Flow Rate and Temperatures are recorded to Analyze differe GRT Workshop Prague Each BHE is equipped with Flowmeter and Temperature Sensors. Flow Rate and Temperatures are recorded to Analyze different operational Configurations. a) Single-U-BHE b) Duplex-U-BHE c) Coaxial-BHE. Source: EA Geothermie, Graphics after: Sass & Mielke Clemens Lehr 11

12 Border Conditions Geology and Environment - Vast homogeneous Geology (e.g. Granite, Clay, etc.) - Low Groundwater Influence - Groundwater Observation Wells - Weather Station -Technical -Stable Power Supply Clemens Lehr 12

13 Drilling Cored Drilling Geophysical Survey Geophysical Investigation on Cores (e.g. Thermo-Scanner, Porosity, Saturation, etc.) Controlled Completion - Straight Completion with Spacers - Monitored Grouting -Thermophysical Approval -> Backfilling -Thermopysical Investigation -> Border Conditions/ Groundwater/ EGRT C. Lehr Geothermie-Kongress Dortmund

14 Spacer Square Tubing Cross Section Borehole BHE Cable Strap Clemens Lehr 14

15 Clemens Lehr 15

16 C GRT Workshop Prague Depth Missing Grout Time [s] Clemens Lehr 16

17 Minute Groundwater Flow Undesturbed Start Heating Phase End Heating Phase Circulation Clemens Lehr 17

18 EA-Geothermie - Recommendations on Design, Construction, Operation and Monitoring (2016) The recommendations summarise the state of the art. Their aim is the proper exploitation of the ground for geothermal purposes without adversely affecting the ground or the groundwater on the one hand and the operation of the system and nearby buildings on the other. The recommendations should be used during consulting, design, installation and operation in order to achieve optimum and sustainable use of the ground at a specific location. Authorities responsible for supervising and approving projects can use the recommendations as a guide when taking decisions and making stipulations. Edited by German Geological Society e.v. (DGGV) and German Geotechnical Society e.v. (DGGT) Clemens Lehr 18

19 Thank You! Clemens Lehr 19

20 ሶ GRT Workshop Prague The result of the evaluation of GRT data by inverse numerical approximation of the T(t)-Curve (Best Fit) is the effective thermal conductivity [λ eff ] and the effective volumetric heat capacity. The effective values include conductive and convective thermal flow. The evaluation is based on Kelvin s Line Source or Cylinder Source Approach. ν r, t = Q H 4πλ eff Ei r 2 4αt α = thermal diffusivity Τs Ei = exponential integral Q H = specific heating ሶ power WΤm r = distance to heating source m Δυ = difference to undesturbed temperature of the underground K λ eff = effective thermal conductivity WΤ mk π = Pi m Clemens Lehr 20

21 Clemens Lehr 21 Ingersoll & Plass (1948) were presenting an approximate solution. Recently GRT results are still evaluated in using the linear steady state like behaviour (straight line method) which is a simplified derivation from Ingersoll & Plass equation. Using this simplified simplification leads to a loss of important informations [e.g. near field information at beginnig of the test, volumetric heat capacity is not determinable]. 4 H eff Q b H H f R Q r t Q T t T ln 4 ) ( Simplyfications