Ground Source Heatpump Applications presentation given by Simon Rees to CIBSE Yorkshire. March 2016

1. School&of&Civil&Engineering
FACULTY&OF&ENGINEERING
School&of&Civil&Engineering
FACULTY&OF&ENGINEERING
Ground=source&Heat&Pump&
Applications
CIBSE&Yorkshire
March&16th 2016
Simon&Rees
S.J.Rees@leeds.ac.uk

2. Outline
• Heat*pump*principles
• Historical*developments
• Domestic*field*trials
• Non6domestic*Systems*6
• Ground*heat*exchange
• System*Integration
• Measured*Performance
• GSHP*Research
Rees,%S.%and%R.%Curtis%(2014)%National%Deployment%of%Domestic%Geothermal%Heat%Pump%
Technology:%Observations%on%the%UK%Experience%1995–2013.%Energies.%7(8):%5460T5499
Free%online%at:%http://www.mdpi.com/1996T1073/7/9/6224

3. Heat&Pump&Principles
• Based&on&a&vapour=compression&
refrigeration&cycle
• Heat&is&‘pumped’ by&a&compressor:&more&
heat&out&than&electrical&power&in.
• Coefficient&of&Performance&defines&
thermodynamic&efficiency
• The&smaller&the&temperature&difference&
Inside=to=outside,&the&greater&the&
efficiency.
Compressor
Heat Rejected ( to
the heat sink at high
temperature ( )TH
QH)
Compressor Electrical
Power ( )P
Heat extracted (
the heat source at low
temperature (T )
QC) from
C

4. Heat&Pump&Characteristics
Staffell,%I%(2009).%A)review)of)domestic)heat)pump)coefficient)of)performance,%2009.%

5. Heat&Sources:&Air&or&Ground?
The&ground’s&high&thermal&mass&means&it&has&a&
temperature&that&is&more&favourable&for&heat&exchange&
than&the&air.
!10
!5
0
5
10
15
20
25
Temperature)(°C))
Time)()mm)yy))
Daily+Mean+Ground+Loop+Average+Fluid+Temperature Daily+Mean+Air+Temperature Initial+Ground+Temperature+(+12.3+°C+)

6. Ground&Temperatures
CIBSE&TM51&
(Busby&et&al.&2009)
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7. Approaches&to&Ground=coupling
The&coupling&with&the&ground&can&be&through&
closed=loop&systems&with:
• Vertical&borehole&heat&exchangers&(100=
150m&typical&in&UK)
• Single&U=tube
• Double&U=tube
• Co=axial
• Horizontal&loops&with&straight&pipe
• ’Slinky’&horizontal&loops
Water&sources&can&be&used&through:
• Extraction&from&wells,&rivers,&lakes&(open&
loop)
• Closed&loops&submerged&in&lakes
Seasonal&storage&can&be&achieved&using&large&
groups&of&boreholes&(BTES)&or&pairs&of&wells&in&
aquifers&(ATES).
Single
U-tube
Double
U-tube
Co-axial
E
C

8. Horizontal&Slinky&Heat&
Exchangers
Source:&GeoScience&Ltd
Source:&Carbon&Trust

9. Heat&Exchanger&Technology
Vertical&Boreholes:&Drill,&
Insert,&Grout.

10. Energy&Piles&and&Walls
REHAU Soga*and*Rui (2016)*Energy*Geostructures

11. Seasonal&Performance
• Coefficient*of*Performance*(COP)*is*a*steady6state*
parameter*at*particular*operating*conditions*(catalogue*
values).
• Seasonal*Performance*Factor*(SPF)*is*based*on*seasonal*
energy*inputs*and*outputs.*This*is*of*more*interest*in*
evaluating*real*performance
• SPF*is*the*ratio*of*total*useful*thermal*energy*to*system*
electrical*energy*consumed.
• In*reality*systems*are*complex*and*SPF*can*be*calculated*
different*ways*depending*on*what*electrical*demands*are*
included.
• Heating*and*cooling*can*be*separated:*SPFH,*SPFC

12. SPF&Defined
• SPF1 is*heat*pump*product*alone
• SPF2 includes*the*ground*loop*pump
• SPF3 includes*supplementary*heater
• SPF4 includes*the*heating*circulating*pump

13. SPF&Target&Values
• Acceptable*values*vary*depending*on*the*comparison*being*made:*
site*energy,*primary*energy,*carbon*saving,*running*cost,*
renewable*contribution…
• A*modern*domestic*gas*boiler*system*has*SPF4 about*0.85.
• For*carbon*benefits*in*the*UK,*HP*SPF4 needs*to*be*>*2.21
• For*cost*savings*(DECC*2014*values)*SPF4 needs*to*be:
• >*2.49*relative*to*gas
• >*1.9*relative*to*LPG
• >*1.65*relative*to*oil
• For*the*purposes*of*the*RES*Directive*SPF2 >=*2.5*to*be*classed*as*
renewable*(saving*primary*energy).

14. Historical&Developments

15. Early&Heat&Pump&Pioneers
• Originally&proposed&by&Lord&Thompson&Kelvin&
“On&the&Economy&of&the&Heating&or&Cooling&of&
Buildings&by&Means&of&Currents&of&Air.”&Proceedings+
of+the+Physical+Society+of+Glasgow 3:&269–72.
• Further&comments&in&a&book&‘The&Steam&Engine&
and&other&Heat&Engines’&(1910)&by&James&Alfred&
Ewing:&“Burning+fuel+to+warm+a+room+by+a+few+
degrees+is+a+wasteful+way+to+utilise+heat”.
• First&GSHP&patent&by&Swiss&engineer,&Heinrich&
Zoelly in&1912.

16. Early&Heat&Pump&Pioneers
Haldane,&T.G.N.&1930.&“The&Heat&Pump===an&Economical&Method&of&Producing&
Low=Grade&Heat&from&Electricity.”&Journal+of+the+Institution+of+Electrical+Engineers
68&(402):&666–75.
Results&from&his&Glasgow&home:&
1926=1928&season
Haldane’s&proposal&for&a&River=source&
heat&pump&and&radiant&panel&system

17. Early&work&in&the&USA
Crandall,&A.C.&1946.&“House&Heating&with&Earth&Heat&Pump.”&
Electrical+World 19&(November&9):&94–95.
‘Earth&coils’&were&metal&pipes&to&directly&evaporate&
the&refrigerant&(DX)

18. The&origins&of&GSHP:&USA
Coogan,%C.%H.%1948.%The)residential)heat)pump)in)
New)England.%Waterbury,%CT,%USA:%Connecticut%
Light%and%Power%Co.

19. A&Divergence&of&Opinions…
The%heat%pump%holds%promise%of%permitting%the%industry%to%supply%domesticT
heating%service%in%an%economical%manner.%Up%until%now%the%electric%utility%
industry%has%supplied%very%little%of%this%market%and%we%think%that%without%the%
heat%pump%we%are%not%likely%ever%to%supply%very%much%of%it.
Andrews,%S.%W.%1948.%The%Heat%Pump%From%the%Utility’s%Point%of%View.%
Transactions)of)the)American)Institute)of)Electrical)Engineers,%67(1),%562–564.%
undesirable%electrical%features%such%as%highTstarting%current,%lowTpower%
factor,%and%high%demand,%which,%otherwise,%would%have%adverse%economic%
effects%upon%the%electric%supply%system%and%thus%result%in%economic%
handicaps%in%the%utilization%of%the%electrical%service%by%this%device.%
Bary,%C.%1948.%The%Heat%pump%– Its%Significance%As%a%Potential%Residential%
Load.%Electrical)Engineering,%p.%340T344.%

20. The&origins&of&GSHP:&UK
Proceedings)of)the)IEE)Part)A:)Power)Engineering,%1956,%104(15),%262–271.%

21. Origins&of&the&GSHP:&UK
Comment%from%J.%Sumner%(1957)%in%response%to%Miriam%Griffith’s%
presentation:
It%has%been%said%that%nowadays%we%cannot%afford%the%capital%
required%to%build%heat%pumps.%I%understand%that%the%National%
Coal%Board%is%proposing%to%spend%£1000%million%in%the%next%ten%
years%in%order%to%increase%the%output%of%coal%by%10%million%tons%a%
year.%I%think%it%could%be%demonstrated%that,%if%the%N.C.B.%were%to%
allocate%even%£1%million%of%this%to%building%heat%pumps,%they%
could%conserve%more%coal%than%if%it%were%spent%on%new%plant.%

22. After&the&1950s&…
In&the&UK:
• Miriam&Griffith&and&BEAIRA&did&no&further&work
• John&Sumner&was&a&lone&campaigner&for&HP&technology
• Natural&Gas&was&a&clear&winner
• Some&EA&Technology&work&on&ASHP&in&70/80s
• No&GSHP&interest&until&mid&1990s
In&the&rest&of&the&world:
• The&immediate&post&war&US&oil&shortage&eased&– little&further&interest&
in&50/60s
• Domestic&air&conditioning&demand&in&the&USA&grew&hugely
• The&1973&oil&crisis&saw&a&big&spurt&in&GSHP&research&– National&Labs,&
Universities,&Utilities&and&IGSHPA.&Similarly&in&Europe&(Sweden&and&
Switzerland)&but&not&UK.
• Plastic&pipe&meant&corrosion&and&DX&could&be&avoided.&Better&
compressors&by&the&80s

23. Current&Worldwide&Deployment
1400000
981667
476842
314502
144069
141833
122250
94288
85307
51638
45986
31038
22750
19908
13200
8875
6996
5500
4272
3201
3020
2839
2828
2597
1250
1144
106
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000 USA
China
Sweden
Germany
France
Switzerland
Canada
Austria
Finland
Denmark
Netherlands
Poland
UK
CzechGRep.
Italy
Estonia
Belgium
Slovenia
Bulgaria
Ireland
Portugal
Slovakia
Lithuania
Hungary
Romania
Spain
Luxembourg
Installations

24. Current&Worldwide&Deployment
50285
17554
15794
11214
9253
6697
4390
3915
3874
2749
2676
2207
1895
942
805
723
698
631
583
525
358
286
261
222
202
62
24
0
10000
20000
30000
40000
50000
60000
Sweden
Switzerland
Finland
Austria
Denmark
Estonia
USA
Germany
Canada
Netherlands
Slovenia
France
CzechGRep.
Lithuania
Poland
China
Ireland
Belgium
Bulgaria
Slovakia
UK
Portugal
Hungary
Italy
Luxembourg
Romania
Spain
Installaions)per)million)captia

25. Large&Systems&in&the&UK
Churchill&Hospital,&Oxford
240&x&100m&borehole
8&x&500kW&heat&pumps

26. Domestic&Systems&in&the&UK

27. UK&Developments&(later&1990s)
Initial&installations:&one=off&‘low&
energy’ houses&and&refurbs
Source:&GeoScience Ltd

28. Along&came&ECC&and&Clear&Skies&…
Source:&GeoScience Ltd

29. UK&Support&Programmes
Grant&programmes
• Clear&Skies&(£10m,&8.2%&for&GSHP)
• Low&carbon&building&Programme&(£139m)
• Renewable&Heat&Premium&Payments&(RHPP)
Supplier&Obligation&programmes
• Energy&Conservation&Commitments:&ECC1,&ECC2&(£500m)
• Carbon&Emissions&Reduction&Target:&CERT&(£1.2bn)
• Energy&Company&Obligation:&ECO&(£1.3bn&– now&cut)&
Current&programmes:&RHI&and&Green&Deal&.&ECO&does&not&
support&renewables

30. UK&Support&Programme&Outcomes&
to&2014
0
5000
10000
15000
20000
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Cumlative*GSHP*Installations
Year
Other0funding
RHPP
EEC1,0EEC2,0CERT
Clear0Skies0&0LCBP

31. National&Trials&and&Monitoring
• EST&National&Field&Trial&– Phase&1&(54&GSHP&sites)
• Monitored&‘system&efficiency’
• User&research&by&the&Open&University
• DECC&technical&investigation
• EST&National&Field&Trial&– Phase&2.&After&a&range&of&
interventions
• RHPP&– more&detailed&monitoring&but&without&
manufacturers.&User&data&from&online&questionnaires.&Initial&
results&published&in&2014.
• Related&domestic&fields&trials:&
Stafford,%A.,%&%Lilley,%D.%(2012).%Predicting%in%situ%heat%pump%performance:%An%
investigation%into%a%single%groundTsource%heat%pump%system%in%the%context%of%10%
similar%systems.%Energy)and)Buildings,%49,%536–541.%

32. Field&Trial&Results&– Phase&1

33. Field&Trial&Results&– Phase&1&
Findings
A&number&of&systems&with&Efficiencies&>&3&but&some&very&poor&performing&
systems
Main&technical&findings:
1. under=sizing&of&the&heat&pumpq
2. under=sizing&of&the&ground&heat&exchangerq
3. poor&insulation&standards&(pipes&and&tanks)q
4. flow&temperature&unnecessarily&highq
5. excessive&pump&usage&(time&control&or&number&of&pumps)q
6. poor&control.
Non=technical&findings&from&user&surveys:
• 86%&satisfied&with&heating&performanceq
• only&63%&satisfied&with&level&of&supportq
• only&62%&satisfied&with&cost&savingsq
• controls&not&easy&to&understand&and&use.
Issues&for&the&industry:&changes&to&Micro=generation&Certification&Scheme&
standards&(MIS),&better&training,&better&user&support&and&information.

34. Field&Trial&Results&– Phase&2

35. Field&Trial&Results&– RHPP&2013
• Mean&SPF4 is&2.92,&System&efficiency&2.74&(from&2.39)
• 84%&of&systems&would&be&classed&as&renewable
• 85%&would&show&carbon&savings&relative&to&gas&heating
• 64%&would&show&cost&savings&relative&to&gas.&Nearly&all&RHPP&participants&
saved&money&as&initial&fuel&was&not&gas

36. Further&Technical&Challenges
• Performance&levels&are&improving&but&still&not&as&high&
as&other&EU&trial&results
• Some&systems&are&still&‘failures’
• User&survey&highlights&some&control&issues
• UK&Specific&issues:&small&houses,&high&thermal&mass,&
high&heating&temperatures?

37. Non=Domestic&Systems:&
Ground&heat&exchange

38. Ground&heat&exchange
The*design*question:*for*a*given*set*of*heating*and*cooling*demands,*how*many*
and*how*deep*do*the*boreholes*need*to*be?
Key*design*points:
1. System*efficiency*depends*on*fluid*temperatures* and*so*we*want*these*to*be*
close*to*the*‘undisturbed’*or*background*ground*temperature.
2. The*relationship*between*fluid*temperatures* and*the*ground*temperature*
depends,*in*general,*on
• Ground*thermal*conductivity
• Borehole*thermal*resistance.
3. Long*term*(seasonal)* temperatures* depend*on*long*term*energy*exchange:*
• design*is*based*on*annual*energy*demands*– not*just*peak*loads.
• consider*several*years*of*operation*to*find*the*min/max*fluid*temperature*range.
4. In*design*methods*(software)*we*define*the*temperature*limits*we*want*to*
work*with*(targets).*These*can*be*based*on:*
• Heat*pump*min/max*operating*temperatures
• Values*that*are*going*to*give*the*SPF*we*are*looking* for

39. Borehole*resistance*and*ground*
conductivity
• First,*think*about*rejecting*a*given*amount*of*heat*per*meter*of*borehole.
• Local*temperature*gradient*depends*on*the*thermal*resistance*of*the*
components*in*the*borehole*and*the*thermal*conductivity*of*the*ground
• High*thermal*resistance*means*fluid*temperatures* have*to*be*higher*to*
reject*a*given*amount*of*heat.

40. Borehole*resistance*and*ground*
conductivity
• Borehole*resistance*depends*on
• Configuration*– single,*double*or*co6ax
• Pipe*size*and*spacing
• Grout*properties*– thermally*enhanced*
grouts*are*often*used
• Borehole*diameter*– typically*1206150mm.
• Fluid*resistance*– flow*rate*and*fluid*
properties*(Reynolds*number).
!"
∗
=
%& − %"
("
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Rg[(m$K)/W]
λg [W/(m$K)]
Zeroth0order2Multipole
10th0order2Multipole
Bauer2et2al.2(2011)
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Ra[(m$K)/W]
λg [W/(m$K)]
Zeroth.order0Multipole
1st.order0Multipole
10th.order0Multipole
Javed and%Spitler (2016)

41. System&hydraulic&design
• Propylene&or&Ethylene&glycol&based&mixtures&are&the&common&heat&
transfer&fluids&for&geothermal&systems
• Viscosity&is&noticeably&higher&than&water&and&varies&with&temperature&
significantly
• Reynolds&numbers&can&be&low&and&heat&transfer&drop=off&without&care.
• Some&optimization&is&required:
• High&flow&rate&gives&better&heat&
transfer
• Higher&flow&rate&gives&higher&pressure&
drop&and&pump&energy&demand
• Pump&demand&no&more&than&3%&of&
heat&delivered&is&required&for&
compliant&domestic&systems

42. Long6term*borehole*field*response
• Long*term*temperature* trends*are*
important*and*depend*on*annual*
heating*and*cooling*energy*balances
• Whether*the*long*term*trend*is*rising*or*
falling*temperatures* depends*on*
whether*heating*or*cooling*is*dominant
• Borehole*depth*is*selected*on*the*basis*
of*the*long6term*trend
• Balanced*demands*lead*to*the*most*
economical*solutions*– shortest*
boreholes.
• Max*and*min*temperatures* depend*on*
a*combination*of*demands*and*peak*
loads
• Simulation*results*are*needed*to*
estimate*the*costs*accurately
15
17
19
21
23
25
27
29
31
33
35
37
0 1460 2920 4380 5840 7300
Temperature3[°C]
Simulation3Days3
163bh 323bh 1203bh
!70
!55
!40
!25
!10
5
20
35
50
65
80
0 730 1460 2190 2920 3650 4380 5110 5840 6570 7300 8030 8760
Time0(hours)
Building0Loads0(kW)

43. Borehole&field&configuration
• After&a&few&seasons,&boreholes&interact&– temperature&
changes&at&one&influence&those&at&neighboring&boreholes.
• This&effect&is&well&understood&and&can&be&modelled.
0
2
4
6
8
10
12
14
16
18
0 5 10 15 20
ΔT)(°C)
Distance)(m)
DT DT)1 DT)2

44. Borehole&field&configuration
• Different&configurations&(rows&
and&columns&of&boreholes)&
respond&differently&e.g.&2&x&6&
is&not&the&same&as&3&x&4&etc.&
• Response&characteristic&also&
depends&on&spacing/depth&
ratio.
• Response&can&be&
characterized&by&‘g=function’&
data.&This&relates&temperature&
change&to&heat&input. 0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
(5 (4.5 (4 (3.5 (3 (2.5 (2 (1.5 (1 (0.5 0 0.5 1 1.5 2 2.5 3 3.5
ln(t/ts)
g(t/ts,rb/H=0.0005)

45. Borehole&Array&Design
Simulation
of+GHE
Adjust+size
User+input:
GSHP+Loads+&+
(optionally)
GHE+Loads
User+inputs:+
Ground+properties
BH+info.
HP+characteristics
HP+Simulation
Spitler and%Bernier%(2016).%Vertical%Borehole%Heat%Exchanger%Design%Methods
Ground&heat&exchanger&design&software&helps&with&the&iterative&process&
needed&to&find&the&design&heat&exchanger&size

46. Essential&Design&Data
To&summarize:&the&design&data&needed&is:
1. Local&undisturbed&ground&temperature
2. Ground&thermal&conductivity&and&diffusivity
3. Building&heating/cooling&rejection&demands&(monthly)
4. Monthly&peak&heating&and&cooling&loads
5. Borehole&resistance&– pipe&size,&spacing,&grout&properties,&
borehole&diameter
6. Target&temperature&range&for&the&system&– avoiding&
freezing&and&high&pressure&limit,&or&targets&for&SPF.

47. Ground&Thermal&Response&Testing
Ground&thermal&conductivity&is&a&key&parameter&– how&do&we&
estimate&it?
• Reference&book&valuesq
• British&Geological&Survey&desktop&study
• In=situ&Thermal&Response&Testing&(TRT)&f

48. In&Situ&Thermal&Response&Testing
1. A&single&test&borehole&is&completed
2. A&closed&circuit&is&formed&and&electrical&heaters&used&to&
apply&a&pulse&of&heat&over&48+&hours.
3. Flow,&power&and&temperature&data&are&collected&and&
analyzed.

49. Typical&TRT&Responses
The&key&data&needed&for&
analysis&is&the&average&fluid&
temperature&and&power&input
Data& source:& IGSPHA
Data& source:& Groenholland

50. Research&Equipment
Photos:&J.D.&Spitler
Electric&heaters&
(3&x&3kW)
Flow&
meter
Flow/return&temp.&
sensors
Pumps&and&
purge&valves

51. Compact&Site&Equipment
A.&Chaisson
Groenholland Geo&Energy&Systems

52. TRT&Analysis
1. Plot&temperature&vs natural&log&of&time
2. Find&the&slope&– ignoring&some&early&data
3. Use&the&slope&to&derive&the&effective&conductivity
! =
#
4%&'
!
Where&s is&the&slope&of&the&
temperature&vs natural&log&time&plot

53. Non=Domestic&Systems:&
System&Integration

54. System&Integration
Operating&temperatures
• Chilled&water&temperatures&can&be&in&the&usual&range&– hence&able&to&
serve&AHUs,&Fan&Coils&etc.
• Heating&temperatures&can&be&up&to&55&but&better&at&40/45.&Hence&well&
suited&to&underfloor&heating/&oversized&radiators,&fan&coils.
Central&Plant&Integration&– 3&basic&approaches
1. Reversible&heat&pumps&with&sliding&headers.
2. Reversible&heat&pumps&with&Independent&header&
connections.
3. Reversing&on&the&water=side&and&heat&exchange&
between&buffer&tanks.

55. Sliding&header&configuration
CIBSE&TM51
• Header&is&split&between&
heating&and&cooling&
depending&on&valve&position&
and&demand
• Heat&pumps&are&controlled&
in&sequence&according&to&
heating/cooling&demand&by&
BMS.
• Heat&pumps&can’t&be&
independently&switched&
between&heating&and&
cooling.

56. Independent&Header&Connections
Naicker and&Rees&(2011)

57. Plantroom installation
Header&pipes&and&valves

58. Water=side&reversing&and&
buffer&tanks
Groenholland Geo&Energy&Systems

59. Plantroom Installation&(Skids)
Groenholland Geo&
Energy&Systems

60. Non=Domestic&Systems:&
Measured&Peformance

61. • A*multi6use*building*(15,607*m2)
• Monitored*since*opening*in*Jan.*
2010
• GSHP*system*provides*all*AHU*
and*FCU*cooling*(360*kW*peak)*
and*all*underfloor heating*(330*
kW*peak*capacity)***
• Has**Four*Water*Furnace*26stage*
reversible*heat*pumps
• 56*x*100m*deep*borehole*heat*
exchangers,*125mm*diameter.*
30*l/s*peak*flow
Monitoring*at*De*Montfort*University*
Hugh*Aston*Building
Naiker,%S.S.%(2016)%Performance%Analysis%of%a%LargeTscale%Ground%Source%
Heat%Pump%System.%PhD%Thesis:%De%Montfort%University.

62. Hugh&Aston&Building&Ground&
Heat&Exchangers
19&+&37&arrays,&100m&deep

63. Heat&Pump&Installation
Header&
pumps
Ground&loop&
pumps
Header&pipes&and&valves

64. Monthly&Heat&Balances
0
2
4
6
8
10
12
14
16
18
20
'0.6
'0.4
'0.2
0
0.2
0.4
0.6
0.8
1
Temperature)(°C))
Heat)Exchange)(MWh)
Time)(mmm)8 yy)
Monthly0daily0Mean0Heat0Extraction(MWh) Monthly0daily0Mean0Heat0Rejection(MWh) Monthly0daily0Mean0Net0Heat0Exchange0(0MWh)
Monthly0daily0Mean0Ground0Loop0Temp.0(°C0) Monthly0daily0Mean0Air0Temp.0(°C0)

65. System&Efficiencies
2.89
3.99
3.31
2.69
2.22
3.55
3.87
3.67
3.16
2.61
3.19
4.06
3.54
2.97
2.49
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
SPF//H1 SPF/C1 SPF/1 SPF/2 SPF/4
SPF
May/52010/to/April/52011 May/52011/to/April/52012 Feb/52010/to/July/52012
Year%(%Season) SPF%%H1 SPF%C1 SPF%1 SPF%2 SPF%4
May%52010%to%April%52011 2.89 3.99 3.31 2.69 2.22
May%52011%to%April%52012 3.55 3.87 3.67 3.16 2.61
Feb%52010%to%July%52012 3.19 4.06 3.54 2.97 2.49
Seasonal&performance&
Factors:
• SPF1&is&heat&pump&alone
• SPF2&includes&the&ground&loop&
pump&demand
• SPF&4&includes&the&
heating/cooling&header&pumps
RES&Directive&requires&
SPFH2&>&2.5

66. Dynamic&Operation
Only&one&compressor&stage&is&needed&for&much&of&the&time.&
On/off&control&leads&to&short&cycle&times.
0
5
10
15
20
25
30
35
%"of""Occurrence
Hourly"kWh
Heating Cooling
0
5
10
15
20
25
30
%"of"Occurrence
Daily"kWhr
Heating Cooling
0
1
2
3
4
5
6
7
10
11
12
13
14
15
16
17
18
Flow%(l/s)
Temperature%(°C)
Time%(Date%Hour)
Source0side0outlet0Temperature0(°C) Source0side0intlet0Temperature0(°C) Source0side0Flow0rate0(l/s)

67. Dynamic&Operation
0
1
2
3
4
5
6
7
8
0 200 400 600 800 1000 1200
Daily&&SPFH1
Daily&Heating&Demand&(kWh)
0
1
2
3
4
5
6
7
8
9
0 200 400 600 800 1000 1200
Daily&&SPFC1
Daily&Cooling&Demand&(kWh)
0
10
20
30
40
50
60
0(1 1(2 2(3 3(4 4(5 5(6 6(7 >7
%""of"Occurrence
Hourly"SPFH1
Cycle0Time0(0(100min/cycle) Cycle0Time0(11(200min/cycle) Cycle0Time0(21(300min/cycle)
Cycle0Time0(31(400min/cycle) Cycle0Time0(41(500min/cycle) Cycle0Time0(51(600min/cycle)
0
5
10
15
20
25
30
35
40
45
0'1 1'2 2'3 3'4 4'5 5'6 6'7 >7
%"of"Occurrence
Hourly"SPFC1
Cycle0Time0(0'100min/cycle) Cycle0Time0(11'200min/cycle) Cycle0Time0(21'300min/cycle)
Cycle0Time0(31'400min/cycle) Cycle0Time0(41'500min/cycle) Cycle0Time0(51'600min/cycle)

68. Circulating&Pump&Operation
Pump&sizes&are&large&relative&to&compressor&sizes
Pumps&also&operate&unnecessarily&– valve,&flow&switch&
and&control&faults
0
10
20
30
40
50
60
70
80
90
100
Operational+Hours++/%
Time+(+mmm/yy)
Compressor2Operational2Hours2;%22(Both2Cooling2and2Heating2)2 Useful2Heating2and2Cooling2Energy2Delivered2Across2Manifold2; Hours2%
Heating2or2Cooling2Loop2Circulating2Pump2Operational2Hours22; % Ground2Loop2Circulating2Pump2Operational2Hours2; %

69. Circulating&Pump&Energy&Demands
Pump&demands&have&a&big&effect&on&SPF2 and&SPF4
Monthly&Pump&to&Compressor&Power&Ratio&Vs Monthly&SPF2,&SPF4
0
0.5
1
1.5
2
2.5
3
3.5
0 0.2 0.4 0.6 0.8Monthly(SPF4
Power(Ratio(((Wp(SPF4)(/Wc)
0
0.5
1
1.5
2
2.5
3
3.5
4
0 0.1 0.2 0.3 0.4
Monthly(SPF2
Power(Ratio(((Wp(SPF2)(/Wc)

70. Improving&Performance
Overall,&performance&is&satisfactory.&
Cycle&times&would&be&improved&by
• Smaller&lead&machine
• Variable&compressor&speed
• Buffer&tanks
Lift&could&be&reduced&by&heating&temperature&
tuning/reduction
Pump&energy&demands&could&be&reduced&by:
• Better&hydraulic&design
• More&robust&control&(fault&detection/correction)
• Reduced&start=up/shut=down&running
• Ground&loop&demand&control

71. Geothermal&Heat&Pump&
System&Research

72. The&EU&Horizon&2020&Programme
Aim:&reduced&complexity,&improved&
robustness&and&efficiency
Key&Technologies:
• Innovative&drilling&technology
• High&efficiency&heat&exchanger
• Dual=source&heat&pump
• Robust&control&systems&and&
monitoring
• Foundation&heat&exchange&
systems
Geothermal&Technology&for&Economic&
Cooling&and&Heating

73. even at laminar flow conditions and, at the same time, achieve this with a
Geothermal heat pumps are widely recognized as very efficient systems f
applications that combine a high potential for saving on primary energ
emissions with a very long life span and low maintenance. Different way
pump with the ground are in use, but by far the largest number of systems
exchanger placed vertically to depths varying between perhaps 30 and 40
called "Borehole Heat Exchangers" (BHE) heat is exchanged between
fluid flowing through the loop and heat pump) and secondary side (the gr
temperature difference.
Figure 1. Impression of the Geothex heat exchanger showing the insulated inner pipe an
Geothex BV). Shown is the functioning in heat extraction mode with flow through the inn
annulus.
As with any heat exchanger, there is a relation between the amount of h
thermal resistance of the heat exchanger (R) and the temperature differe
primary and secondary side:
q = T/R
This implies that, for a given constant heat flux rate, the higher the therma
exchanger, the larger the required temperature difference between the
Now, the efficiency of the heat pump depends mainly on the differenc
(cold) and sink (hot) temperatures. In fact, it can be shown that for every
The&EU&Horizon&2020&Programme

74. The&EU&Horizon&2020&Programme
• A&hybrid&dual=source&approach:&air&and&ground&heat&
exchanger&for&optimal&choice&of&source/sink&
temperature
• Variable&speed,&DC&permanent&magnet&motor,&scroll&
compressor,&refrigerant&R32.
• Hybrid&design&and&smart&controls&make&the&
implementation&robust
• Reduced&complexity&to&improve&uptake&(consumers,&
developers&and&SMEs).
New&Heat&Pump&Development&in&the&GEOTeCH project&=

75. Sources&of&information
http://geotrainet.eu
http://www.gshp.org.uk
http://www.igshpa.okstate.edu
http://www.egec.org
CIBSE&TM45,&TM51&and&CP2&– via&knowledge&portal
Useful&web&sites:
UK
EU
US

76. Thank&you&for&listening
S.J.Rees@leeds.ac.uk