building services engineering chalmers optimization of ground coupled heat pump systems saqib javed...
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Building Services Engineering CHALMERS
OPTIMIZATION OF GROUND COUPLED HEAT
PUMP SYSTEMS
Saqib Javed (PhD Researcher)
Per Fahlén (Research Leader)
Johan Claesson (Supervisor)
EFFSYS 2 meeting 2009-12-14
Akademiska Hus
CarrierCTC / Enertech
Donghua UniversityFastighetsägarna
GeotecGrundfos
IVTLTHNCCNibe
SWECO TAC
Thermia VärmeWilo
ÅF-Infrastruktur
Building Services Engineering CHALMERS
• Identifying key optimization factors for Ground Coupled Heat Pump (GCHP) systems using modelling, simulations field studies and experiments.
• Developing simple and user-friendly models and calculation tools to facilitate designers and researchers interested in the complete system optimization.
OBJECTIVE
EFFSYS 2 meeting 2009-12-14
Building Services Engineering CHALMERS
LITERATURE REVIEW
EFFSYS 2 meeting 2009-12-14
• Single boreholes: Long term response can be modelled using simple existing analytical models with reasonable accuracy.
• Multiple boreholes: Shortage of analytical models for both long and short term response.
• Need of an analytical model which:
- is capable of simulating both short-term and long-term response of GHE.
- considers all significant heat transfer processes in GHE.
- retains the actual geometry of the borehole.
Building Services Engineering CHALMERS
CASE STUDY
EFFSYS 2 meeting 2009-12-14
• Astronomy-House, Lund University
Floor area: 5300 m2
Heating demand: 475 MWh Cooling demand: 155 MWh
• Ground system
20 boreholes Rectangular configuration Each 200 m deep
MonthQh
[MWh]Qc
[MWh]Jan 97.9 -Feb 89.3 -Mar 69.8 3.4Apr 40.9 7.3May 20.9 15.0Jun - 25.7July - 33.2Aug - 31.3Sep - 19.2Oct 31.4 13.3Nov 47.5 6.4Dec 77 -
Year 475 155
Building Services Engineering CHALMERS
EFFSYS 2 meeting 2009-12-14
# Borehole wall temp (Tw) Temperature penalty (Tp)
1 Cylindrical Source Infinite length line source
2 Cylindrical Source Finite length line source
3 Infinite length line source Infinite length line source
4 Finite length line source Finite length line source
5 Superposition borehole model (SBM)
SIMULATING MULTIPLE BOREHOLES
Tb = brine temperatureTw = borehole wall temperatureTp = temperature penalty from neighbouring boreholes
Building Services Engineering CHALMERS
MEAN BRINE TEMPERATURES
EFFSYS 2 meeting 2009-12-14
8
9
10
11
12
13
14
15
16
-3
-1
1
3
5
7
9
0 5 10 15 Max
imu
m m
ean
bri
ne
tem
per
atu
re [
ºC]
Min
imu
m m
ean
bri
ne
tem
per
atu
re [
ºC]
Year
CS (borehole interaction with infinite LS) CS (borehole interaction with finite LS) Infinite LS (borehole interaction with infinite LS) Finite LS (borehole interaction with finite LS) SBM
Maximum mean brine temperature →
← Minimum mean brine temperature
Building Services Engineering CHALMERS
• Javed, S., Fahlén, P. and Holmberg, H., 2009. Modelling for optimization of brine temperature in ground source heat pump systems. Proceedings of 8th international conference on sustainable energy technologies; SET2009, Aachen, Germany. August 31- September 3.
• Javed, S., Fahlén, P. and Claesson, J., 2009. Vertical ground heat exchangers: A review of heat flow models. Proceedings of 11th international conference on thermal energy storage; Effstock 2009, Stockholm, Sweden. June 14-17.
• Fahlén, P, 2008. Efficiency aspects of heat pump systems - Load matching and parasitic losses. IEA Heat pump centre Newsletter, vol. 26, nr. 3, 2008-08, (IEA.).
PUBLICATIONS
EFFSYS 2 meeting 2009-12-14
Building Services Engineering CHALMERS
LITERATURE REVIEW
EFFSYS 2 meeting 2009-12-14
• Single boreholes: Long term response can be modelled using simple existing analytical models with reasonable accuracy.
• Multiple boreholes: Shortage of analytical models for both long and short term response.
• Need of an analytical model which:
- is capable of simulating both short-term and long-term response of GHE.
- considers all significant heat transfer processes in GHE.
- retains the actual geometry of the borehole.
Building Services Engineering CHALMERS
MODELLING
EFFSYS 2 meeting 2009-12-14
• Existing Analytical models:
– Equivalent pipe / cylinder instead of a U-tube.
– Thermal capacities of the water and the pipe are often ignored.
– Response is a function only of the distance (r) from the centre of the equivalent pipe.
Building Services Engineering CHALMERS
MODELLING
EFFSYS 2 meeting 2009-12-14
• New Analytical models:
– Two pipes in the ground.
– Accounts for the thermal short circuiting between the two legs of the U-tube.
– Response is a function of both x and y.
– Can predict the short time response accurately.
Building Services Engineering CHALMERS
MODELLING
EFFSYS 2 meeting 2009-12-14
• New Analytical models:
– Two pipes in the grout surrounded by the ground.
– Accounts for the thermal properties of both the grout and the ground.
Building Services Engineering CHALMERS
MODELLING
EFFSYS 2 meeting 2009-12-14
• New Numerical model:
– Solved the heat transfer problem in 2D using conformal coordinate system.
– Used for the validation of the analytical model.
Building Services Engineering CHALMERS
LITERATURE REVIEW
EFFSYS 2 meeting 2009-12-14
• Single boreholes: Long term response can be modelled using simple existing analytical models with reasonable accuracy.
• Multiple boreholes: Shortage of analytical models for both long and short term response.
• Need of an analytical model which:
- is capable of simulating both short-term and long-term response of GHE.
- considers all significant heat transfer processes in GHE.
- retains the actual geometry of the borehole.
Building Services Engineering CHALMERS
• Development of a test facility.
• Experiments to determine:
– Thermal response for heat extraction and injection conditions.
– Flow effects.
– System effects.
• Validation of the developed models.
EXPERIMENTS
EFFSYS 2 meeting 2009-12-14
Building Services Engineering CHALMERS
LABORATORY DEVELOPMENT
EFFSYS 2 meeting 2009-12-14
Building Services Engineering CHALMERS
LABORATORY DEVELOPMENT
EFFSYS 2 meeting 2009-12-14
Building Services Engineering CHALMERS
BRINE & CHILLED WATER SYSTEM
EFFSYS 2 meeting 2009-12-14
EK-KB1-1
DN32
AT2 +5--+15 °C
KB2 processkylvatten
VVX-KMK1
P-KB2-2
AV-KMK1-1
P-KB2-1
P-KMK1-1
AT1 -10--+10 °C
VP1
P-VP1-2
P-VP1-1
P-KB1-2
P-KB1-1
VP2
Toppen
Botten
Borrhålslager
Botten
Toppen
KMK1
AV-KMK1-2
VV-KMK1-1
P-BH1 till 9
RV-BH1 till 9
KB1 processköldbärare
VP2
DN50
DN50
DN32
DN32 DN32
DN32
DN32
DN32
DN32
DN32
DN32
DN32
DN32
EK-KB2-1
GT-AT1-1
GT-AT1-2
GT-AT2-1
GT-AT2-2
GF-KB1-1 GT-KB1-1
+
GT-BH-1 -- 9
GT-BH-10 -- 19
GT-KMK1-2
GT-KMK1-1
GT-VVX-KMK1-2
GT-VVX-KMK1-1
GT-VP1-2-2
GT-VP1-2-1
AV-KB1-1
AV
-KB
1-2
AV-KB1-6
AV-KB1-3
AV-VP1-2-2
AV-VP1-2-1
AV-AT1-2-1 -- 3
SÄV-EK-KB1-1
GT-VP1-1-1 GT-VP1-1-2 AV-VP1-1-2
AV-VP1-1-1
AV-KB1-7
AV-KB1-4
GT-KB1-3
EP2
GT-KB1-2
AV-KB1-5
Building Services Engineering CHALMERS
HOT WATER SYSTEM
EFFSYS 2 meeting 2009-12-14
VB1 processvärmevatten DN32
DN40
DN32
VP2
P-VP2-2
P-VP2-1
VP3
P-VP3-2
P-VP3-1
AT2 KB2-tank
AT2 KB2-tank
AT3 +30--+55 °C
Botten
Toppen
DN32 EK-VB1-1
AT4 +30--+55 °C
Botten
Toppen
DN40 VB1 värmesystem
Fra
m
Fra
m
Ret
ur
Ret
ur
GT-AT3-1
GT-AT3-2
GT-AT4-1
GT-AT4-2
EK-VB1-2
VVX-KMK2
VV-VP2-1
VV-VP3-1
pro
cess
värm
e +
20--
+50
°C
AV-KMK2-2
P-KMK2-1
DN32 AV-KMK2-1
VV-VB1-2
VV-VB1-1
P-VB1-2
P-VB1-1 P-VB1-3
DN32 DN40 DN40
DN32
DN40
GT-VP3-2-2
AV-VP2-1-2 AV-VP2-1-1
GT-VP2-1-2
GT-VP2-1-1
GT-VB1-3
GT-VB1-2
GT-VP3-2-2 GT-VB1-1 GT-VP3-2-1
SÄV-EK-VB1-1
SÄV-EK-VB1-2
AV-VP3-1-2
AV-VP3-1-1
GT-VP3-1-2
GT-VP3-1-1
AV-AT3-1
AV-AT3-2
AV-AT3-3
AV-AT4-1
AV-AT4-3
AV-AT4-2
AV
-VB
1-1
AV-VP2-2-1 AV-VP2-2-2
AV-VP3-2-1
AV-VP3-2-2
BV-VP3-2-1
BV-VP2-2-1
VB2
DN32
DN32
DN32
DN40
DN
40
Building Services Engineering CHALMERS
GROUND HEAT EXCHANGER SYSTEM
EFFSYS 2 meeting 2009-12-14
Laboratory Building
BH-1 BH-2 BH-3
BH-4 BH-5 BH-6
BH-7 BH-8 BH-9
2,1
2,2
4,1
4,0
2,0
3,9
4,0
4,04,0
4,0
4,1
4,4
3,9
4,0
4,7
0,1
N
Building Services Engineering CHALMERS
THERMAL RESPONSE TESTING
EFFSYS 2 meeting 2009-12-14
Building Services Engineering CHALMERS
INITIAL RESULTS
EFFSYS 2 meeting 2009-12-14
Ground thermal conductivity: 3 W/m-K
Undisturbed ground temperature: 9 °C
Building Services Engineering CHALMERS
CONCLUSIONS
EFFSYS 2 meeting 2009-12-14
Conducted a state-of-the-art literature review.
Presented different approaches to model multiple borehole systems.
Developing new analytical and numerical methods.
Carrying out experiments.
Building Services Engineering CHALMERS
EFFSYS 2 meeting 2009-12-14
QUESTIONS / COMMENTS
THANK YOU!
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