ubeg gbr - dr. e. mands & sauer umwelt - baugrund - geothermie - geotechnik zum boden 6, d-35580...

UBeG GbR - Dr. E. Mands & Sauer

Umwelt - Baugrund - Geothermie - GeotechnikZum Boden 6, D-35580 Wetzlar, Tel.: 06441 212910

Email: e.Mands@UbeG.de

Exploration of thermal underground conditions

Geothermal Response Test

and design of

Borehole Heat Exchangers Systems

Geology of Hessen

Kassel

Bad Hersfeld

Alsfeld

Gießen

WiesbadenFrankfurt

Darmstadt

FuldaVogelsberg

Odenw ald

Spessart

Rhön

Westerw ald

OsthessischeTafel

Vulkanites

Soils / Sand / C lay / S ilt

M esozoikum (250m io J - 65m io J) Sandstone / L im estone

Palaeozoic (ä ler a ls 250m io J) / Schists / Sandstones

1,6 – 2 W/mK

2-2,5 W/mK1,8 – 2,6 W/mK

Granites 2,5 – 3,5 W/mK

Heat conductivity

4,0

1

2

3

4

Gravel dry - saturatedQuarzit

1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 2,8 3,0 3,2 3,4 3,6 3,8

Thermal Efficiency (W /m), 1800 h/a

heat conductivity (W /m /K)

5

10

15

20

Regular Case

for single residential houses, w ith groundwater flow

clay m oisture to saturated

Diorite

Dolom ite

Granite

Limestone

Marl

Sand, dry - saturated

Sandstone

Schists

Thermal Conductivity

Underground Specific extraction rate

General standard values:

Poor underground conditions ( <1,5 W/mK)

Regular rock and saturated soils ( =1,5-3,0 W/mK)

Rocks with > 3,0 W/mK

Specific Rocks1:

Gravel, Sand dry

Gravel, Sand saturated

Clay, Silt, Loam

Limestone (massiv)

Sandstone

Magmatite (e.g. Granit)

Vulcanites (e.g. Basalt)

Gneiss

20 W/m

50 W/m

70 W/m

<20 W/m

55 – 65 W/m

30 – 40 W/m

45 – 60 W/m

55 – 65 W/m

55 – 70 W/m

35 – 55 W/m

60 – 70 W/m

Um welt Baugrund G eotherm ie G eotechnik

D a t a - l o g g e r

E l e c . P o w e r

H e a t e r

M o b i l e G e o t h e r m a l T e s t Evaluationperiod

Tim e [Seconds]200.000150.000100.00050.000

22

20

18

16

14

12

10

Determination of

• Thermal Conductivity

• Borehole thermal Resistance

• undisturbed underground temperature

T TQ

k

ed

Q

kI X

x

0 2 2

2

' '

Geothermal-Response-Tests

Um welt Baugrund G eotherm ie G eotechnik

• First generation of Mobile Geothermal Test in Germany 1999

First comercial test in Germany

Commercial Geothermal Test in Germany

Um welt Baugrund G eotherm ie G eotechnik

in flo w to G e RT a n d to th e h e a tin g e le m e n ts

o u tflo w fro m c irc u la tio n p u m p a n d fro m G e RT

h e a tin g e le m e n ts a n d in flo w in to c irc u la tio n p u m p 3 h ea tin g e lem en ts 2 K W 3 K W 4 K W

circu la tio n p u m p

m u ltid a ta sen so r a n d in stru m en t

ex p a n sio n v esse l

m a n o m eter

o u tflo w G eR T

in flo w G eR T

fillin g tu b e

tem p era tu re sen so r o u tflo w G eR T

2 K W4 K W

tem p era tu re sen so r in flo w G eR T

th erm o sta t

p a d d le flo w sw itch

a ir b leed v a lv e

L o o p 2

L o o p 1o u tflo w G eR T

in flo w G eR T

p ressu re co n tro l v a lv e

a ir b leed v a lv e

a ir b leed v a lv e

B lo ck A

B lo ck B

B lo ck C

B lo ck D

Second generation of

Mobile Geothermal Test

computer-controlled

Hardware

Um welt Baugrund G eotherm ie G eotechnik

3. Generation of Mobile Geothermal Test (compact)

with small catapillar

Max. Heat load 9kW, steppless regulation

Computer-Controlled

Hardware

Um welt Baugrund G eotherm ie G eotechnik

Automatic evaluation: - Datenfiles can be read directly into the soft ware - Controle of result by stepwise evaluation

Software GeRT-CAL

Um welt Baugrund G eotherm ie G eotechnik

A constant increase and irregular behaviour of the stepwise evaluation curve shows an influence of groundwater

Step-w ise Evaluation

Tim e [Seconds]240.000220.000200.000180.000160.000140.000120.000100.00080.00060.00040.000

6

5

4

3

2

1

0

Testdauer: without groundwater influence

Evaluation Period

Tim e [Seconds]200.000150.000100.00050.000

35

30

25

20

15

10

Step-w ise Evaluation

Tim e [Seconds]180.000160.000140.000120.000100.00080.00060.00040.000

10

9

8

7

6

5

Evaluation Period

Tim e [Seconds]180.000160.000140.000120.000100.00080.00060.00040.00020.000

22

21

20

19

18

17

1615

14

13

Groundwater influence

Stepwise evaluation

Um welt Baugrund G eotherm ie G eotechnik

100

90

80

70

60

50

40

30

20

10

0

6 8 10 12 14 16 18 20 22 24

Vor Testbeginn unmittelbar nach Testende 1h nach Testende

Temperatur [°C]

Tie

fe [

m]

Information from the Temperature log:

Determination of undisturbed underground temperature

Determination of Geothermal Gradient

Gives information about irrregular thermal conductivity

Shows the influence of Groundwater

Temperature-profile

Undisturbed(before Test)

1h after end of test

Directly after end of test

Um welt Baugrund G eotherm ie G eotechnik

80

70

60

50

40

30

20

10

0

-10

8 10 12 14 16 18 20 22 24 26

vor Testbeginn 1,0 h nach Testende 2,0 h nach Testende

Temperatur [°C]

Tie

fe [

m] 10.11.2006 00:00 11.11.2006 00:00 12.11.2006 00:00 13.11.2006 00:00

10

15

20

25

30

Vorlauf R ücklauf

Datum und U hrzeit10.11.2006 00:00 11.11.2006 00:00 12.11.2006 00:00 13.11.2006 00:00

0

1000

2000

3000

4000

5000

6000

7000

Step-w ise Evaluation

Tim e [Seconds]240.000220.000200.000180.000160.000140.000120.000100.00080.00060.00040.000

6

5

4

3

2

1

0

Example GeRT Berlin 11/2006

Um welt Baugrund G eotherm ie G eotechnik

80

70

60

50

40

30

20

10

0

10 12 14 16 18 20

vor Testbeginn 1,0 h nach Testende 2,0 h nach Testende

Temperatur [°C]

Tie

fe [

m]

Step-w ise Evaluation

Tim e [Seconds]240.000220.000200.000180.000160.000140.000120.000100.00080.00060.00040.000

6

5

4

3

2

1

0

17.10.2006 12:00 18.10.2006 12:00 19.10.2006 12:00 20.10.2006 12:00

10

15

20

25

Vorlauf R ücklauf

Datum und U hrzeit17.10.2006 12:00 18.10.2006 12:00 19.10.2006 12:00 20.10.2006 12:00

0

1000

2000

3000

4000

5000

6000

7000

Example GeRT Camburg 10/2006

Um w elt Baugrund G eotherm ie Geotechnik

GGeeB BUUExperience with Geothermal Tests

1,0 1,5 2,0 2,5 3,0 3,5 4,01,0

1,5

2,0

2,5

3,0

3,5

4,0

m easured [W /(m x K )]

n = 86

fluctuation range for ground source heat pum p w ith 30kW :+- 2 BHE (100m )

Um welt Baugrund G eotherm ie G eotechnik

m easured [W /(m ,K)]

Exam ple:

60 kW heating 1.800h/a30 kW C ooling (free) 800h/a

Predesign w ith =2,3 W /(m , K )-> 10 x 100m BH E

C ost for Energy (e lec. pow er)e lec pow er: 178 €/M W helc. pow er for H P : 130 €/M W h

SPF anual extra costcost over 15 years

Anual Cost caused by undersized BHE

2,32,11,91,7

3,83,32,92,6

0 €570 €

1.150 €1.700 €

0 €8.500 €

17.250 €25.500 €

Benefit of Gethermal-Response-Test

Um w elt Baugrund G eotherm ie Geotechnik

GGeeB BUU Undersized

0,0 0,1 0,2 0,3 0,4 0,5 0,60

200

400

600

800

1000

1200

1400

1600

1800

Difference estim ated - m easured conductiv ity

50 kW

40 kW

30 kW

additional cost increase w ith undersizing of BH E

additional cost (3 Years) 3 .400,00 EU R

additional cost (4 Years) 3.600,00 EU R

additional cost (5 Years) 3.400,00 EU R

Cost for a Geothermal Response Test +- 3400€

Um w elt Baugrund G eotherm ie Geotechnik

GGeeB BUUOversized

I

H eating load: 50 kW

Full load hours : 2 .100 h /a

Yearly heating 105 M W h/a

L itho logy C laystona

estim ated conductiv ity 2 ,2 W /(m x K )

C O P 4,0

BH E: D oppel-U , 32 m m

D eapth: 102,2 m

N um ber o f BH E: 12

Tota l m eter BH E 1.226,4

D istance of BH E: 8 m

VD I 4640: Tonste in 1,1 - 3,5 W /(m x K )

Thermal conductivity [W/(m x K)]

Length of BHE Total length [m] Cost [EUR] Difference

2,2 102,2 1.226,4 91.980,00 -

2,4 96,7 1.160,4 87.030,00 4.950,00 2,6 91,5 1.098,0 82.350,00 9.630,00 2,8 86,7 1.040,4 78.030,00 13.950,00

Cost for a Geothermal Response Test +- 3400€

Heating load Full load hours / a COP / SPF of heat pump Cooling load full load hours cooling / a COP /SPF cooling (peak load heating and cooling). COP= Coefficient of Performance SPF = Standard Performance Factor

Design of BHE - System

Input information from HVAC - Engineers

Input Underground

Fixed Values Thermal conductivity Response Test (fix value)

Heat capacity Literature (fix value)

Values which can be changed Playground for the engineer

Type of BHE

Single / double U Coaxial BHE

Length of BHE 20-200m Grouting Material Thermal grout

Bentonite / Cement Size of borehole (Depends of Geology)

Grouting Material Thermal grout Bentonite / Cement

EED Calculation

Type of BHE Example: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

E infach-U -S onde

D oppel-U -Sonde

25-32 m mein fache K oaxia lsonde

kom plexe K oaxia lsonden

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

8

6

4

2

0

-2

-4

Double U-BHE

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

8

6

4

2

0

-2

-4

-6

-8

Single U-BHE

Comparison and recommendation Example: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

Double U-BHE

165m Total BHE length

Single U-BHE

195m Total BHE length

A Double U- BHE has 10-15% more efficiency than a single U-BHE

Depth of BHEExample: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

8

6

4

2

0

-2

-4

1 x 165m

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

6

4

2

0

-2

-4

-6

2 x 82,5m

Comparison and recommendationExample: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

Single BHE (deep)

165m Total BHE length

Two BHE (shallow)

184m Total BHE length

For purly heating purposes a single deep BHE is more efficient than two shallow BHE

Borehole diameter Example: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

8

6

4

2

0

-2

-4

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

8

6

4

2

0

-2

-4

-6

152mm diameter 180mm diameter

Comparison and recommendationExample: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

Diameter 152mm

165m Total BHE length

Diamter 180mm

178 m Total BHE length

Kleiner Bohrlochdurchmesser wirkt sich günstig auf die Entzugsleistung aus

Grouting-materialExample: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

8

6

4

2

0

-2

-4

Base loadPeak cool loadPeak heat load

Year 25JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Flui

d te

mpe

ratu

re [º

C]

8

7

6

5

4

3

2

1

0

-1

Bentonit-Zement Verpressung Thermisch verbessertes Material

Grouting Material

0,00

0,05

0,10

0,15

0,20

0,25

100 120 140 160 180 200 220Bohrlochdurchmesser (mm)

therm

ischer B

ohrlochw

iders

tand konventionelle Verfüllung

thermisch verbesserte Verfüllung

Linear (konventionelle Verfüllung)

Linear (thermisch verbesserteVerfüllung)

Comparison and recommendationExample: 10 KW Heating 2100 Full load hours

Heat conductivity of underground 2,5 W/m/k

Cement – Bentonite Grouting

165m Total BHE length

Thermal Grout e.g. STÜWATHERM

128 m Total BHE length

Thermal Grout has 15% more efficiency

Sumary

•The design of BHE – Systems is in Germany under the regulation of VDI 4640

•Geological investigations are always necessary (interpretion of geological maps)

•The design can be done by diagrams, tables, and calculations. •Project with more than 30KW heating load should be calculated

•Furthermore Geothermal Response Tests should be performed from 30KW and more

•Thermal enhanced grouting material should be used for all BHE drillings (STÜWA – THERM)