The FKW CO Earth Heat Pipe as

FKW Research Center for Refrigeration and Heat Pumps, Hannover, Germany

The FKW CO2 Earth Heat Pipe asEarth Probe for Geothermal Heat Pumps

Prof. Dr.-Ing. Dr. h.c. H. KruseFKW Research Centre of Refrigeration and Heat PumpsFKW Research Centre of Refrigeration and Heat Pumps

Weidendamm 12-14, 30167 Hannover, Germany

EU Workshop, Brussels28 .05 .2008

Content

Seasonal Performance Factor SPF f G d S H t P ith B i E th P bof Ground Source Heat Pumps with Brine Earth Probes.

EU Project for improving Ground Source Heat Pumps for higher Efficiencies and Temperatures.

Improving Borehole Heat Exchangers by applying thethermodynamic principle of a Thermosyphon Heat Pipe.

Prsentation 25.05.03 2

Summary

Study and EU Project GROUND HIT show that it is possible to achieve reasonable high SPF with HFC-refrigerants by application of the earth-to-water system.

Ground Source heat pumps as developed by GROUND HIT

3

Ground Source heat pumps as developed by GROUND HIT offer a good basis for further improvements by optimizing the

Bore Hole Heat Exchanger BHE .

Improvement of Bore Hole Exchanger

- Conventional:Brine Earth ProbeBrine Earth Probewith water-glycol or water-salt solutionsGround Water Endangering Class 1, Germany: (WG1)

- Innovative:CO2 Earth Heat Pipe 2 pCarbon Dioxide: not ground water endangering (WG -)

- Improvement: Energy and Environment:- Air and Ground Water

Brine Earth Probe and CO2 Earth Heat Pipe

X PolyethyleneU-type tubeU-type tube Brine Earth Probe

X Corrugated stainless steel singlesteel single tube CO2 Heat Pipe

X Thermosyhon principle

Installation of the Heat Pipe Head in a Subsurface Shaft

An easy installation in the standard shaft ( 120 cm)

being outside in the open area in the subsoil under the new building

Swiss Study on Geothermal Heat Pumps Seasonal Performance Factors (BfE 2004)

Prsentation 25.05.03 7

Innovative FKW CO2- Earth Heat Pipe

CO2-Heatpipe (EWR) consists of

Pipe (to 300 m length) Coil and Shell Heat Exchanger(Adjusted to the EHP heat extraction)

German Patent No. 198 60 328A1, Registered Design No. 012040141

Corrugated Stainless Steel Pipe

X Spirally groovedfl ibl i i

X Liquid film in thei i b tflexible pipe is

best suited for aneven distributionof the downwardflowing liquid filmat the inner wall

inner grooves is bestprotected against theshear stress fromthe upward flowingvapour in the core ofthe pipe preventingat the inner wall

circumference.the pipe, preventingentrainment effects.

9

Inserting a Stainless Steel Pipe into the Borehole

10

Experimental Comparison of CO2 Earth Heat Pipe and Brine Earth Probe

11

Field Test in Berlin Earth Heat Pipe and Brine Earth Probe

CO2 Heat Pipe Head Heat Pump Compressors and Condensers Brine Tube Head

T e m p e r a t u r e n z w is c h e n 3 u n d 6 U h r in C

0

V e r s u c h : 0 4 . 0 6 .0 5 0 U h r - 0 6 . 0 6 . 0 5 0 U h r D a t e n d e r K l t e a n la g e a n d e r 1 0 0 m la n g e n S o l e - S o n d e

3 0

3 5

4 0

3 0

3 5

4 0

R 4 0 7 C - V e r d a m p f u n g s t e m p . d e r S o le s o n d e S o le - E in t r i t t s t e m p e r a tu r in d i e E r d eR 4 0 7 C - V e r d a m p f u n g s t e m p . d e r C O 2 - S o n d e C O 2 - E in t r i t t s te m p e r a t u r in d i e E r d eA u e n t e m p e r a t u r F l s s ig k e i t v o r A K V ( R 4 0 7 C )

F l s s ig k e i t v o r A K V

Temperatures in the Refrigerant Cycle and at the outside Wall of the CO2 Heat Pipe depending on time and borehole depth

T e m p e r a tu r e s o n t h e o u ts id e w a l l o f t h e e a r t h p r o b e

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

Teuf

e in

m

- 2 0

- 1 5

- 1 0

- 5

0

5

1 0

1 5

2 0

2 5

3 0

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

Z e i t [ h h ]

Tem

pera

tur [

C]

- 2 0

- 1 5

- 1 0

- 5

0

5

1 0

1 5

2 0

2 5

3 0

R 4 0 7 C - V e r d a m p f u n g s te m p e r a t u r d e r C O 2 - S o n d e

R 4 0 7 C - V e r d a m p f u n g s t e m p e r a t u r d e r S o le s o n d e

S o le - E in t r i t t s t e m p . in d ie E r d e

C O 2 - E in t r i t t s t e m p . in d ie E r d e

A u e n t e m p e r a t u r

T e m p e r a tu r e n a n d e r A u e n w a n d d e s E rd w r m e ro h re s4 4

8 0

9 0

1 0 0-4-3-2-101234

R o h r w a n d t e m p e r a tu r in C

- 4

- 3

- 2

- 1

0

1

2

3

4

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

Z e it [h h ]

Tem

pera

tur [

C]

-4

-3

-2

-1

0

1

2

3

4

E r d te m p . b e i 4 0 m

R o h r t e m p . b e i 4 0 m

R o h r te m p . b e i 5 0 mR o h r t e m p . b e i 1 0 m

R o h r te m p . b e i 3 0 mR o h r te m p . b e i 9 0 m

R o h r te m p . b e i 8 0 m

13

Period Brine Inlet

Evaporating

Condensing Temp. tc

Heat extraction

CO2Inlet

Evaporating Temp. to

Cond. Temp. tc

Heat extraction

Results of Measurements at the Brine and the CO2 probe

Temp [C]

Temp. toR407C [C]* at

dew line

R407C [C]* at dew line

rate of brine earth probe

[W/m]

Temp. [C]

R407C [C]* at dew line

R407C [C]* at

dew line

rate of CO2 earth probe

[W/m]

20.-23.5.05: 60 h - - - - -1.4 -6.4 44.4 56.5

1.-2.6.05: 24 h - - - - -3.3 -8.3 26.9 60.4

4.-6.6.05: 48 h -1.4 -13.9 37.6 42.4 -3.9 -9.1 37.5 60.0

7.-8.6.05: 18 h -0.5 -13.5 51.9 43.4 -3.6 -8.8 51.0 61.7

Temperatures at the CO2 Heat Pipe and the Brine Earth Probe

Test Results and calculated COP Values of the Brine Earth Probe and the CO2 Earth Heat Pipe at

different Heat Extraction Rates

System tB1 tB2 tB i t t COP COPh t tE th Q lSystem tB1 tB2 tBrine to tc COPc COPh tom tEarth Qo l

[oC] [oC] [K] [oC] [oC] - - [K] [K] [W/m] m

Brine -1.4 +0.2 1.6 -13.9 37.6 2.81 3.81 13.3 12.3 42.4 100

CO2 -3.9 -3.9 0 -9.1 37.5 3.23 4.23 5.2 15.4 60 100

CO2 +0.6 +0.6 0 -4.6 37.5 3.71 4.71 5.2 10.9 42.4 100

Conclusion

CO2 Heat Pipe with an equal heat pump leads to adifferent heat extraction rate of 60 W/m as thedifferent heat extraction rate of 60 W/m as theBrine Earth Probe with 42,4 W/m.Heating COP is 11% better for the CO2 EHP( No brine pump power has been taken into consideration)

CO2 Heat Pipe at an equal heat extraction rate as theBrine Earth Probe of 50 W/m results in anHeating COP of 25% better than the BEP.( No brine power pump has been taken into consideration )

Pilot Systems with FKW-CO2 Heat Pipes in Germany and Austria 2005 - 2007

Location Type of heat pumpHeating capacity

Length of the heat pipe Cooling capacity Sub soil Start upheat pump capacity heat pipe

Schriesheim Hoval DV8P 8,5 KW 1 x 100m 6,6 KW silt/rock 15.09.05

Bad Knig Hoval DV7P 5,5 KW 1 x 80m 4,3 KW silt/rock 18.10.05

Crailsheim Hoval DV15P 15 KW 2 x 100m 12 KW lime stone 24.10.05

Emsbach Hoval DV8P 8,5 KW 1 x 100m 6,6 KW lime stone 15.04.06

Nordheim/Heilbronn Hoval DV8P 8,5 KW 1 x 100m 6,6 KW silt/lime stone 15.10.06

Ludwigshafen Hoval DV8P 8,5 KW 1 x 100m 6,6 KW sand/groundwater 10.11.06

Kappelrodeck/Achern Hoval DV7P 5,5 KW 1 x 80m 4,3 KW silt/rock ?

Eppingen/Richen Schrag 8,5 KW 1 x 100m 6,6 KW silt/rock 05.07

Bammental Hoval 8,5 KW 1 x 100m 6,6 KW silt 11. 07.

Waldburg(A) Ochsner ? 1 x 100m ? ? ?

Scheme of Heat Pump with CO2 Heat Pipe in Schriesheim

First Pilot Heat Pump with CO2 Heat Pipe in Schriesheim

Hoval heat pump: Inside construction of the heat pump without evaporator

I t ll ti f th tInstallation of the evaporator as a probe head in the norm shaft

Research and Development

FKW Research Project

R&D:

- Comparison of a CO2 Heat Pipe with Brine Earth Probe

- Experience with inserting stainless Steel Heat Pipe into pe e ce t se t g sta ess Stee eat pe toBore Hole

- Development of Heat Pipe HX and Compact Heat Pump

Drilling Work forEarth Probes Testfield at FKW

100m Stainless Steel Pipefor CO2 BHE

Inserting the Heat Pipeinto the Borehole

Shaft with the Connection Canalto the Building

An easy installation in the

Installation of the Heat Pipe Head in the Shaft

An easy installation in the standard shaft ( 120 cm)

being outside in the open area in the subsoil under the new buildingbuilding

X FFfff

FKW Basement and Parking lot with 3 different Earth Probes

Wrmepumpen-

LaborForschungssonde

DN80 100m

SolesondeDoppel U-Rohr DN32 100m

Heat Pipe

Laboratory Research Earth Probe

DN 80 100m

Brine Earth ProbeDouble U-PipeDN 32 100m

27

Heizung

CO2 - ErdwrmerohrDN32 100m

Heating

CO2 Earth ProbeDN32 - 100m

Demonstration Chamber for theCO2- and Brine Heat Pump

Heat Pumps for CO2- and Brine BHE

Research Project: (ENBW+EDF)First Deep CO2 Heat Pipe

X Research Project in Triberg/ BlackforestP i i lX Principle:

One House One Borehole

CO2 heat pipe of 250 meter depth

Capacity: 18 kW

X Heat Pump for Existing BuildingsViessmann EVI- HP (65C)

Research Project: (EnBW+EDF)First Deep CO2 Heat Pipe

Research Partners

EIFER (European Institute for Energy Research) Systherma Planungsbro fr Erdwrmesyteme GmbH Kaeltro Kltetechnik Angewandte Geologie Karlsruhe (University Karlsruhe)

FKW F h f Kl d W h ik FKW- Forschungszentrum fr Klte- und Wrmepumpentechnik

Triberg BlackforestDrilling Place

250 m CO2- Earth Heat Pipe

Upper End of the Heat Pipe with Measurement Installation

Research: FKW and Information: IZW

Forschungs-zentrum fr Kltetechnik und Wrmepumpen GmbH

Informations-zentrumWrmepumpen und Kltetechnik e.V.GmbH