ubeg gbr - dr. e. mands & sauer umwelt - baugrund - geothermie - geotechnik zum boden 6, d-35580...
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UBeG GbR - Dr. E. Mands & Sauer
Umwelt - Baugrund - Geothermie - GeotechnikZum Boden 6, D-35580 Wetzlar, Tel.: 06441 212910
Email: [email protected]
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)