building services engineering chalmers optimization of ground coupled heat pump systems saqib javed...

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


• 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



LITERATURE REVIEW


• 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.


CASE STUDY


• 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



# 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


MEAN BRINE TEMPERATURES


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


• 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



LITERATURE REVIEW









MODELLING


• 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.


MODELLING


• 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.


MODELLING


• New Analytical models:

– Two pipes in the grout surrounded by the ground.

– Accounts for the thermal properties of both the grout and the ground.


MODELLING


• New Numerical model:

– Solved the heat transfer problem in 2D using conformal coordinate system.

– Used for the validation of the analytical model.


LITERATURE REVIEW









• 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



LABORATORY DEVELOPMENT



BRINE & CHILLED WATER SYSTEM


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


HOT WATER SYSTEM


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


GROUND HEAT EXCHANGER SYSTEM


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


THERMAL RESPONSE TESTING



INITIAL RESULTS


Ground thermal conductivity: 3 W/m-K

Undisturbed ground temperature: 9 °C


CONCLUSIONS


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.



QUESTIONS / COMMENTS

THANK YOU!

building services engineering chalmers optimization of ground coupled heat pump systems saqib javed...

Documents

objective effsys

mwh ground system

borehole wall temperature

brine temperature t

review of heat flow

heat exchange area

dec77 year475155 slide

multiple boreholes t