Thermal Conductivity Intro - Slide 1.1 - 1 Copyright © 2011
Thermal Conductivity and Using ThermallyThermal Conductivity and Using ThermallyEnhanced Grouts to Maximize Borefield PerformanceEnhanced Grouts to Maximize Borefield Performance
Daniel Bernstein -PresidentDaniel Bernstein -President
Gaia Geothermal, LLC
www.gaiageo.comwww.precisiongeothermal.com
Thermal Conductivity Intro - Slide 1.1 - 2 Copyright © 2011
About Gaia Geothermal, LLCAbout Gaia Geothermal, LLC
• USA-based software firm that develops geothermal loopfield design and TC/TRT analysis tools: “GLD” Software
• In business for over a decade• Customers in approx. 60 countries• www.gaiageo.com
Thermal Conductivity Intro - Slide 1.1 - 3 Copyright © 2011
Class OutlineClass Outline
• First things first: Is a geo system justified?• Is a TC test necessary?• What does a TC test look like in the field?• TC test data analysis and report generation• Typical errors and bad data sets• Grouts and Borefield Performance
Thermal Conductivity Intro - Slide 1.1 - 4 Copyright © 2011
Learning ObjectivesLearning Objectives
In today’s presentation you will learn:• A step-by-step process for determining if geo
is a good fit for a project• A step-by-step process for determining when
it is important to conduct a TC test• What a field TC test looks/feels like• What good/bad TC test data look like
Thermal Conductivity Intro - Slide 1.1 - 5 Copyright © 2011
Is a Geo System Justified?Is a Geo System Justified?
• Before you conduct a TC test it is important to first determine if a geothermal system is the right technology for the project
• If a geo system is a good solution a TC test is not always necessary
• There is a logical, analytic framework for determining:– is a geo system justified?– is a TC test warranted?
Thermal Conductivity Intro - Slide 1.1 - 6 Copyright © 2011
Is a Geo System Justified: An ExampleIs a Geo System Justified: An Example
Thermal Conductivity Intro - Slide 1.1 - 7 Copyright © 2011
Client desires GeoExchange system
Determine energy needs•Monthly peak loads•Monthly energy loads•Annual energy balance
Determine site capability•Area available for GHX•Geological constraints•Regulations
Estimate energy cost of various system options
Design conventional system because capital cost and/or site not suitable for installation of Geo-Exchange system
Vertical GHX if site area is limited
Horizontal GHX if space available
Pond/lake GHX if appropriate
Hybrid options - boiler, fluid cooler, waste heat recovery, thermal energy storage, etc.
Design of ground heat exchanger (GHX)
Work with owner, architect, system designer to adjust loads, energy balance
Specifications and drawings
Construction, quality control, commissioning, operator training
Feasibility
Design
Implementation
Open well system if appropriate
Determine system impact•Equipment efficiency•Distribution design temp•Fresh air system
Design of mechanical system
Standing column if appropriate
Estimate construction cost of system options
Confirm geology of site for GHX performance (TC test)
Confirmation
Thanks to Terry Proffer of Major Geothermal
Is a Geo System Justified?Is a Geo System Justified?
Thermal Conductivity Intro - Slide 1.1 - 8 Copyright © 2011
Client desires GeoExchange system
Determine energy needs•Monthly peak loads•Monthly energy loads•Annual energy balance
Determine site capability•Area available for GHX•Geological constraints•Regulations
Estimate energy cost of various system options
Design conventional system because capital cost and/or site not suitable for installation of Geo-Exchange system
Vertical GHX if site area is limited
Horizontal GHX if space available
Pond/lake GHX if appropriate
Hybrid options - boiler, fluid cooler, waste heat recovery, thermal energy storage, etc.
Design of ground heat exchanger (GHX)
Work with owner, architect, system designer to adjust loads, energy balance
Specifications and drawings
Construction, quality control, commissioning, operator training
Feasibility
Design
Implementation
Open well system if appropriate
Determine system impact•Equipment efficiency•Distribution design temp•Fresh air system
Design of mechanical system
Standing column if appropriate
Estimate construction cost of system options
Confirm geology of site for GHX performance (TC test)
Confirmation
Thanks to Terry Proffer of Major Geothermal
Is a Geo System Justified?Is a Geo System Justified?
Thermal Conductivity Intro - Slide 1.1 - 9 Copyright © 2011
Is a Geo System Justified: EnergyIs a Geo System Justified: Energy
Monthly Energy Output* Daylight contours Climate Understanding
Thermal Conductivity Intro - Slide 1.1 - 10 Copyright © 2011
Client desires GeoExchange system
Determine energy needs•Monthly peak loads•Monthly energy loads•Annual energy balance
Determine site capability•Area available for GHX•Geological constraints•Regulations
Estimate energy cost of various system options
Design conventional system because capital cost and/or site not suitable for installation of Geo-Exchange system
Vertical GHX if site area is limited
Horizontal GHX if space available
Pond/lake GHX if appropriate
Hybrid options - boiler, fluid cooler, waste heat recovery, thermal energy storage, etc.
Design of ground heat exchanger (GHX)
Work with owner, architect, system designer to adjust loads, energy balance
Specifications and drawings
Construction, quality control, commissioning, operator training
Feasibility
Design
Implementation
Open well system if appropriate
Determine system impact•Equipment efficiency•Distribution design temp•Fresh air system
Design of mechanical system
Standing column if appropriate
Estimate construction cost of system options
Confirm geology of site for GHX performance (TC test)
Confirmation
Thanks to Terry Proffer of Major Geothermal
Is a Geo System Justified?Is a Geo System Justified?
Thermal Conductivity Intro - Slide 1.1 - 11 Copyright © 2011
Client desires GeoExchange system
Determine energy needs•Monthly peak loads•Monthly energy loads•Annual energy balance
Determine site capability•Area available for GHX•Geological constraints•Regulations
Estimate energy cost of various system options
Design conventional system because capital cost and/or site not suitable for installation of Geo-Exchange system
Vertical GHX if site area is limited
Horizontal GHX if space available
Pond/lake GHX if appropriate
Hybrid options - boiler, fluid cooler, waste heat recovery, thermal energy storage, etc.
Design of ground heat exchanger (GHX)
Work with owner, architect, system designer to adjust loads, energy balance
Specifications and drawings
Construction, quality control, commissioning, operator training
Feasibility
Design
Implementation
Open well system if appropriate
Determine system impact•Equipment efficiency•Distribution design temp•Fresh air system
Design of mechanical system
Standing column if appropriate
Estimate construction cost of system options
Confirm geology of site for GHX performance (TC or pump test if warranted)
Confirmation
Thanks to Terry Proffer of Major Geothermal
Is a Geo System Justified?Is a Geo System Justified?
Thermal Conductivity Intro - Slide 1.1 - 12 Copyright © 2011
Is a Geo System Justified: The SiteIs a Geo System Justified: The Site
Thermal Conductivity Intro - Slide 1.1 - 13 Copyright © 2011
Client desires GeoExchange system
Determine energy needs•Monthly peak loads•Monthly energy loads•Annual energy balance
Determine site capability•Area available for GHX•Geological constraints•Regulations
Estimate energy cost of various system options
Design conventional system because capital cost and/or site not suitable for installation of Geo-Exchange system
Vertical GHX if site area is limited
Horizontal GHX if space available
Pond/lake GHX if appropriate
Hybrid options - boiler, fluid cooler, waste heat recovery, thermal energy storage, etc.
Design of ground heat exchanger (GHX)
Work with owner, architect, system designer to adjust loads, energy balance
Specifications and drawings
Construction, quality control, commissioning, operator training
Feasibility
Design
Implementation
Open well system if appropriate
Determine system impact•Equipment efficiency•Distribution design temp•Fresh air system
Design of mechanical system
Standing column if appropriate
Estimate construction cost of system options
Confirm geology of site for GHX performance (TC test)
Confirmation
Thanks to Terry Proffer of Major Geothermal
Is A Geo System Justified?Is A Geo System Justified?
Thermal Conductivity Intro - Slide 1.1 - 14 Copyright © 2011
Is a Geo System Justified: Payback?Is a Geo System Justified: Payback?
Using GLD, we can conduct a quick and comprehensive lifecycle analysis.
The Geo system payback looks good and the client decides to move forward with geo. Now, it is time to determine whether or not to conduct a TC test.
Thermal Conductivity Intro - Slide 1.1 - 15 Copyright © 2011
Client desires GeoExchange system
Determine energy needs•Monthly peak loads•Monthly energy loads•Annual energy balance
Determine site capability•Area available for GHX•Geological constraints•Regulations
Estimate energy cost of various system options
Design conventional system because capital cost and/or site not suitable for installation of Geo-Exchange system
Vertical GHX if site area is limited
Horizontal GHX if space available
Pond/lake GHX if appropriate
Hybrid options - boiler, fluid cooler, waste heat recovery, thermal energy storage, etc.
Design of ground heat exchanger (GHX)
Work with owner, architect, system designer to adjust loads, energy balance
Specifications and drawings
Construction, quality control, commissioning, operator training
Feasibility
Design
Implementation
Open well system if appropriate
Determine system impact•Equipment efficiency•Distribution design temp•Fresh air system
Design of mechanical system
Standing column if appropriate
Estimate construction cost of system options
Confirm geology of site for GHX performance (TC test)
Confirmation
Thanks to Terry Proffer of Major Geothermal
Is a TC Test Justified?Is a TC Test Justified?
Thermal Conductivity Intro - Slide 1.1 - 16 Copyright © 2011
Is a TC Test Justified?Is a TC Test Justified?
• Before you conduct a TC test it is important to first determine if it is necessary
• First estimate the conductivity• Second, conduct a best case/worst case
sensitivity analysis• Third, compare the best case/worst case
installation costs• Determine whether or not to perform a TC
test
Thermal Conductivity Intro - Slide 1.1 - 17 Copyright © 2011
Is a TC Test Justified: TC EstimatesIs a TC Test Justified: TC Estimates
17
Estimate the TC values from drill logs, data tables, geological data, etc.
Thermal Conductivity Intro - Slide 1.1 - 18 Copyright © 2011
Is a TC Test Justified: Best Case/Worst CaseIs a TC Test Justified: Best Case/Worst Case
Enter the best case/worst case TC values into design software and calculate drilling requirements.
Thermal Conductivity Intro - Slide 1.1 - 19 Copyright © 2011
Is a TC Test Justified: Best Case/Worst CaseIs a TC Test Justified: Best Case/Worst Case
16465.5 14087.2Total Length (ft) Total Length (ft)
Thermal Conductivity Intro - Slide 1.1 - 20 Copyright © 2011
Is a TC Test Justified: Best Case/Worst CaseIs a TC Test Justified: Best Case/Worst Case$296,379 - $253,569.60 = $42809.40
Thermal Conductivity Intro - Slide 1.1 - 21 Copyright © 2011
Is a TC Test Justified: Best Case/Worst CaseIs a TC Test Justified: Best Case/Worst Case
Maximum loopfield cost difference: $42,809TC Test Cost: $10,000Difference: $32,809
Perform a TC test? Absolutely!Why? You might save your clients $32,000!
Thermal Conductivity Intro - Slide 1.1 - 22 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 23 Copyright © 2011
What a Field Test Looks Like: ToolsWhat a Field Test Looks Like: Tools
Thermal Conductivity Intro - Slide 1.1 - 24 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 25 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 26 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 27 Copyright © 2011
Native Ground Temperature: An AsideNative Ground Temperature: An Aside
• Direct measurement– Insert temperature measuring device into loop and
record temperature every X meters and calculate mean
• Circulating temperature measurement– Set logging interval to two seconds and record circulating
data for about ten minutes– Watch for pump heat
Thermal Conductivity Intro - Slide 1.1 - 28 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
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What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 30 Copyright © 2011
Purging Air From The System: An AsidePurging Air From The System: An Aside
• Use bypass valve assembly• Critical to test operation• Critical to stable data collection• Improper purging can cause damage to test
equipment
Thermal Conductivity Intro - Slide 1.1 - 31 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
• Verify all sensors are connected and communicating with the logger
• Start circulating pump and engage the heating elements– You want to obtain ~ 15- 25 Watts per vertical ft of
bore
• Verify proper readings• Secure and lock unit
Thermal Conductivity Intro - Slide 1.1 - 32 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 33 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 34 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 35 Copyright © 2011
What a Field Test Looks LikeWhat a Field Test Looks Like
Thermal Conductivity Intro - Slide 1.1 - 36 Copyright © 2011
Data AnalysisData Analysis
Thermal Conductivity Intro - Slide 1.1 - 37 Copyright © 2011
Data AnalysisData Analysis
• Check that all data are consistent before shutting down test
• Transfer data from logger into GLD or other software tool
• Analyze data set
Thermal Conductivity Intro - Slide 1.1 - 38 Copyright © 2011
Data AnalysisData Analysis
Thermal Conductivity Intro - Slide 1.1 - 39 Copyright © 2011
Data AnalysisData Analysis
Thermal Conductivity Intro - Slide 1.1 - 40 Copyright © 2011
Data AnalysisData Analysis
Thermal Conductivity Intro - Slide 1.1 - 41 Copyright © 2011
Data AnalysisData Analysis
Thermal Conductivity Intro - Slide 1.1 - 42 Copyright © 2011
Data AnalysisData Analysis
Thermal Conductivity Intro - Slide 1.1 - 43 Copyright © 2011
Data AnalysisData Analysis
Thermal Conductivity Intro - Slide 1.1 - 44 Copyright © 2011
TC: 0.98 Btu/hr•ft•⁰F TD: 0.62 ft²/dayT: 55.5° F
Clean, consistent power
44
Good DataGood Data
Thermal Conductivity Intro - Slide 1.1 - 45 Copyright © 2011
TC: 1.11 Btu/hr•ft•⁰F TD: 0.82 ft²/dayT: 61.0° F
Irregular, inconsistent power
45
Bad DataBad Data
Thermal Conductivity Intro - Slide 1.1 - 46 Copyright © 2011
TC: 0.89 Btu/hr•ft•⁰F TD: 0.65 ft²/dayT: 54.0°- 57.0° F
Irregular, inconsistent
power
46
Ugly DataUgly Data
Thermal Conductivity Intro - Slide 1.1 - 47 Copyright © 2011
Ugly Data?Ugly Data?
Thermal Conductivity Intro - Slide 1.1 - 48 Copyright © 2011
0
5
10
15
20
0.1 1 10 100
Tem
per
atu
re R
ise
(F) Uninterrupted Test
Interrupted Test
0
2.8
5.6
8.3
11.1
Tem
per
atu
re R
ise
(ºC
)
Tem
per
atu
re R
ise
(ºF
)
Time (hr)
Ugly Data?Ugly Data?
Thermal Conductivity Intro - Slide 1.1 - 49 Copyright © 2011
0
500
1000
1500
2000
2500
0.1 1 10 100
Time (h)
0
500
1000
1500
2000
2500E
lec
tric
Po
we
r (B
tu/h
r)
0
147
293
737
440
586
Ele
ctr
ic P
ow
er
(W)
Time (hr)
Ugly Data?Ugly Data?
Thermal Conductivity Intro - Slide 1.1 - 50 Copyright © 2011
Learn MoreLearn More
Field Training Course:www.geotrainers.com
Thermal Conductivity Intro - Slide 1.1 - 51 Copyright © 2011
Grout
BoreholeWall
Heat ExchangerPipes
Soil
Grout Conductivity and Borefield PerformanceGrout Conductivity and Borefield Performance
• How does Grout Conductivity Influence Borefield Performance?
Thermal Conductivity Intro - Slide 1.1 - 52 Copyright © 2011
Grout Conductivity and Borefield PerformanceGrout Conductivity and Borefield Performance
• Borefield Performance?Definition: Long term average equipment COP/EER
Equipment COP/EER based on entering fluid temperaturesLong term average system COP/EER
System COP/EER includes circulation pumps
Thermal Conductivity Intro - Slide 1.1 - 53 Copyright © 2011
Example 1
Grout Conductivity and Borefield PerformanceGrout Conductivity and Borefield Performance
• Borefield Performance?
Thermal Conductivity Intro - Slide 1.1 - 54 Copyright © 2011
Grout Conductivity and Borefield PerformanceGrout Conductivity and Borefield Performance
• How does Grout Conductivity Influence Borefield Performance?
1) Grout conductivity influences borehole thermal resistance (BTR)2) Higher grout conductivity = lower BTR = less drilling for a certain level of performance (defined as COP/EER)
EXAMPLE:Case 1 Case 2
Target EER/COP 17.7/4.2 17.7/4.2
BTR 0.21 0.24
Drilling 16250 ft 17985 ft
Thermal Conductivity Intro - Slide 1.1 - 55 Copyright © 2011
• Definition:Ability of grout to transport heat
• Range: varies
• Impacthigher conductivity = more efficient heat transfer = less drilling
Example 1
Grout ConductivityGrout Conductivity
Thermal Conductivity Intro - Slide 1.1 - 56 Copyright © 2011
Example 1
100 borehole system Grout Conductivity Bore length Total length Cost ($12/ft)
0.00 6039ft 603900ft $7,246,800
0.45 369ft 36900ft $442,800
0.57 350.3ft 35030ft $420.360
0.69 341ft 34100ft $409,200
0.79 335ft 33500ft $402,000
0.88 329ft 32900ft $394,800
Grout ConductivityGrout Conductivity
Thermal Conductivity Intro - Slide 1.1 - 57 Copyright © 2011
Example 1
Grout ConductivityGrout Conductivity
Thermal Conductivity Intro - Slide 1.1 - 58 Copyright © 2011
Example 1
1 bag bentonite: $10/ 1 bag of sand: $31:1 ratio costs $13 for 25 ft of grouting with ~ 0.45 conductivity4:1 ratio costs $22 for 25 ft of grouting with ~ 0.88 conductivity
$3300 to drill$290 to grout
$3700 to drill$190 to grout
$3890 $3590
$3450 to drill$220 to grout
$3670
$220 $90
Grout ConductivityGrout Conductivity
Thermal Conductivity Intro - Slide 1.1 - 59 Copyright © 2011
Grout Conductivity and Borefield PerformanceGrout Conductivity and Borefield Performance
• Take Home Message:
1) You can design a geothermal borefield to give you a wide range of performance values (COP/EER)2) By adjusting the grout conductivity, you can possibly save on the
drilling necessary to provide the performance you require3) There is an optimal tradeoff point between the grout conductivity
and drilling savings. For cost effective design, you can calculate it for your project
Thermal Conductivity Intro - Slide 1.1 - 60 Copyright © 2011
Daniel Bernstein –PresidentDaniel Bernstein –[email protected]@gaiageo.com
Gaia Geothermal, LLC
www.gaiageo.comwww.precisiongeothermal.com
Thermal Conductivity Intro - Slide 1.1 - 61 Copyright © 2011
Heat Rate
TrtnTsup
Flow Rate
Cold TempHot Temp
GroundLoop
Test EquipmentTest Equipment