Geothermal Heat Pump Systems

Loading...

Geothermal Heat Pump Systems GeoExchange Technology

Curtis J. Klaassen, P.E. Iowa Energy Center Energy Resource Station

Geothermal Heat Pump Technology „ Introduction „ What is Geothermal Energy? „ Geothermal Heat Pump System Types „ Geothermal System Features ● Pros and Cons ● Applications

„ Economics and the Bottom Line

Questions at Any Time……

1

Energy in Buildings „ Buildings Use 39% of the Nation’s Primary Energy

Total Residential = 21%

21% 28%

Total Commercial = 18% Residential Commercial 18%

Industry Transportation

33%

Energy Efficiency – Building Blocks „ Step 1 – Reduce Energy Load ● Site Orientation and Building Arrangement ● Efficient and Effective Building Envelope

„ Step 2 – Improve Efficiency of Systems and Equipment ● ● ● ●

HVAC Systems – Geothermal Systems Efficient A/C units, Boilers, Motors, Light Fixtures Lighting Systems – Daylighting Computers and Office Equipment

„ Step 3 – Effective Building Operations ● ● ● ●

Proper Control – Energy Management Systems Commissioning Operations and Maintenance – Training and Support Leverage Utility Company Rate Schedules

„ Step 4 – Alternative Energy Sources ● Renewable Energy Options – Solar, Wind, Biomass

2

What Is Geothermal Energy? „ Geothermal Energy is defined as “energy from the internal heat of the earth” ● 47% of the incoming radiation from the sun is absorbed by the earth ● The remainder is absorbed by the atmosphere or reflected back into space

„ Translated: Geo-Thermal means “Earth-Heat” „ “High Temperature” Geothermal Energy ● Energy Source for Hot springs and geysers ● Temperatures exceed 300°F ● Converted to produce useable heat and electricity

“Low Temperature” Geothermal Energy „ Heat Energy contained near the surface of the Earth „ Shallow Earth temperatures fluctuate with seasonal outside air temperature „ Earth temperature becomes more stable with increasing depth „ Nearly constant Earth temperatures at depths below 16 feet „ Earth mean temperature approaches annual average outside air temperature „ Deep Earth temperatures start to increase at depths below 400 feet -- at about 1 °F per 100 feet

3

Low Temperature Geothermal Energy „ Geothermal Heat Pump Systems ● Take advantage of “Low Temperature” Geothermal Energy ● Constant Temperature Year Around – 47 to 50°F in Michigan ● Apply a Water Source Heat Pump to “amplify” the heat energy

„ AKA ● Ground Source Heat Pumps ● Earth Coupled Heat Pumps ● GeoExchange Systems ● Well/Ground Water Heat Pumps ● v.s. High Temperature Geothermal

What are Heat Pumps? „ Characterized by Medium used for Heat Source and Heat Sink ● Air to Air or Air Source ● Water to Air or Water Source ● Water to Water ● Ground Source or Geothermal

„ Capable of Heating, Cooling and producing Hot Water ● Capacity measured in tons ● One ton of capacity = 12,000 BTU per hour (Cooling or Heating) ● Typical new home is about 4 – 5 tons of heating capacity & 2 tons cooling ● Typical Classroom is about 2 – 3 tons of heating or cooling capacity

4

Geothermal Heat Pump System Three Basic Components: „ Heating/Cooling Delivery System ●

Traditional Ductwork / Piping system to deliver heat throughout the building

„ Heat Pump ●

Mechanical Unit that moves heat from the working fluid, concentrates it, and transfers the heat to the circulating air

„ Ground Heat Exchanger ●

Underground piping system that uses a working fluid to absorb or reject heat from the ground

GeoExchange System Types „ Closed Loop System ● ● ● ●

Buried HDPE Piping Underground Heat Exchanger Circulating Fluid contained Exchanges only Heat with the Ground ● Various Configurations

„ Open System ● Ground Water from Well ● Exchanges Heat and Water with the Ground ● Returns Water to the Ground

„ Special Systems ● City Water Interconnect Systems ● Hybrid Systems

5

Horizontal Trench Loop „ Cost effective when land area is plentiful „ Needs 2500 square foot Land area per ton „ Trench depth – Six feet or more GEOTHERMAL PIPE

Courtesy IGSHPA

„ To Produce 1 ton of capacity: ● Trench length – typically 300 feet ● Pipe length – out & back = 600 feet

Horizontal Trench Configurations

Courtesy IGSHPA

6

Horizontal Loop Three Circuits – each with Four Trenches and 4 pipes in each trench

2 inch Headers 3 Circuits

12 Horizontal Trenches Each 300 foot long with Four ¾ inch pipes

Nominal 24 Ton Configuration

Slinky Loop

Slinky Coil – Overlap

Slinky Coil – Extended

„

To Produce 1 ton of capacity: ● ●

Trench length – typically 125 feet Pipe length – out & back = 700 feet

Courtesy IGSHPA

7

Vertical Bore Loop „ Keeps Space required to a minimum „ Needs 250 Square Feet Land area per ton „ Bore Depth – 100 to 300 feet „ Bore Diameter – about 4 to 5 inches „ Bore Spacing – 15 to 20 feet apart „ Nominal Capacity – One ton / 200 ft Bore Hole

Vertical Bore Grouting „ Grouting of Vertical Bore Holes Required ● Seal Borehole to Protect Underground Aquifers ● Maintain Thermal contact between pipe and ground ● Allow movement of pipe

„ Grout Types ● Bentonite Based ● Thermally Enhanced ● Cement Based

„ Pressure Grouting from the bottom up recommended Courtesy ASHRAE GSHP Engineering Manual

8

Vertical Loop

3 Circuits with 8 Bores each Circuit

2 inch Header Pipes

Nominal 24 Ton Configuration

200 foot Deep Vertical Bores with ¾” Pipes

Horizontal Boring „ Horizontal / Directional Boring Machine used ● Horizontal length typically 200 feet for one ton of capacity ● Bore depth controlled at 15 feet ● Setup from one ‘hub’ location for multiple radial bores ● Minimal disturbance to topsoil and landscaping

9

Pond Loop „ Most Cost Effective closed loop design „ Pond Depth – 12 – 15 ft minimum maintained depth „ Pipe Length – One 300 ft. coil per ton (minimum) „ Capacity – 10 to 20 tons/acre of pond

Pond Loop

2 Tons 3 Tons 4 Tons

10

Pond Loop Installation

Open Loop „ Very Cost Effective, providing the following are verified: ● Water Quality is High ●

Water Quantity is Sufficient



Meets Codes and Regulations

„ AKA “Pump and Dump” ● 1.5 to 2 GPM per ton required ● At 30% run time a 4 ton unit could use 100,000 gallons per month ● Typical Family of Four uses about 6,000 gallons per month for domestic purposes

11

GeoExchange System Types „ Special Systems ● Standing Water Well − Extraction and Rejection to the same well − Concentric Pipe – Return water on Outside Pipe − Bleed off water for temperature control

● Interconnection to City Water Mains − Extract heat from water mains with heat exchanger − Return water to water mains downstream

„ Hybrid Systems ● Coldest days -- use auxiliary heat source ● Hottest days -- supplement with cooling tower

GeoExchange System Features Energy Pros and Cons

12

GeoExchange System Features „ Energy Pros + GeoExchange Heating Contribution ● 1 kW electricity plus 3 kW geothermal heat moved from the earth = 4 kW heat delivered ● Heating COP of 3.5 to 4.9

+ GeoExchange Cooling Contribution ● Earth temperature sink cooler than air temperatures = reduced cooling compressor work ● Cooling EER of 14 to 27 (on 2 speed units)

+ Individual units allow zoning for off hour use + Reduced site energy consumption: 30% - 50% less + Lower energy costs: 20% - 30% less

GeoExchange System Features „ Energy Cons − Economizer Free Cooling not normally available − Ventilation/make up air energy handled separately

„ Energy Considerations = EER and COP include allowances for fan and pump energy = Distinction between EER and SEER = Minimize Circulating Pump energy = Water to Water Heating Options

13

Energy Considerations „ Heat Pumps – Ground Source ● Heating Efficiency measured by COP (Coefficient of Performance) ● Cooling Efficiency measured by EER (Energy Efficiency Ratio) ● Efficiency measured at Specific Temperatures and Conditions

Efficiency Rating ARI / ASHRAE / ISO 13256 - 1

Closed Loop COP @ 32°F

Open Loop

EER @ 77°F

COP @ 50°F

EER @ 59°F

Best Available

4.9

27.0

5.5

31.1

High Efficiency

3.6 +

16.0 +

4.6 +

20.0 +

Low Efficiency

2.9

10.6

3.1

11.8

What are the Actual Entering Water Temperatures?

GeoExchange System EWT – Summer

EER = 16 70°F

EER = 20

M

T

W

T

F

S

S

14

GeoExchange System EWT – Winter GeoEx_LWST

GeoEx_LWRT

50

OA_Temp

Supply Temp

40.0 Deg F

45 40 35 34.6 Deg F

Temperature - Deg F

Return Temp 30 25 20 Outside Air Temp 15 10 5 0 -5 -10 -15 Sunday, January 25, 2004

Monday, January 26, 2004

Tuesday, January 27, 2004

Wednesday, January 28, 2004

Thursday, January 29, 2004

Friday, January 30, 2004

Saturday, January 31, 2004

GeoExchange System EWT -- Annual IAMU GLSWT vs. GLRWT (day average): 2001 GLSWT

GLRWT

70

65

64°F

Temperature (Deg F)

60

55

50

48°F 45

40 1/1

1/31

3/2

4/1

5/1

5/31

6/30

7/30

8/29

9/28

10/28

11/27

12/27

Year 2001 Date

15

Energy Considerations „ Circulating Pump Energy ● Pumping Energy Can Be Significant due to 24 / 7 Load Factor ● Minimizing Pump Head effective ● Many Geothermal Systems have excess Pumping Energy ● Circulating Pump Monitored Energy Use: − Represents 8 % of the HVAC Metered Peak Demand − Consumes 36 % of the Total Building HVAC Energy − Responsible for 18 % of the Total Building Energy Costs

„ Evaluate Pumping Options ● Decentralized Loop Distribution ● Two stage parallel pumping ● Variable Flow pumping w/VFD’s

Energy Considerations „ ASHRAE Technical Paper ●“Energy Use of Pumping Options for Ground Source Heat Pumps” An ASHRAE Technical Paper by Stephen Kavanaugh, PhD. and Sally McInerny, Ph.D.,P.E.

120000

Evaluated Energy Consumption of 4 Pumping Systems • • • •

Constant Speed Primary / Secondary Variable Speed Drive Decentralized Pumping

108,600 Annual Pump Energy kWh

100000

80000

65,500 60000

40000

18,800 Majority of Savings due to the ability to cycle off pumps during unoccupied hours and lower pump head requirements

13,100

20000

0 Constant Speed

Primary / Secondary

Variable Speed

Decentralized Loop Pumps

16

Energy Considerations „ Pump Energy Report Card By Stephen Kavanaugh, PhD

Pump Power per 100 tons

Grade

5 or Less

A – Excellent

5 to 7.5

B – Good

7.5 to 10

C – Mediocre

10 to 15

D – Poor

15 or More

F – Bad

Operation and Maintenance Pros and Cons

17

GeoExchange System Features „ Operation and Maintenance Pros + Unitary equipment – failure of one unit + Simple, not complex – Reduces Service Contracts + Avoids Boiler, Condensing Units or Cooling Towers + Elaborate Control Systems not required + No annual Boiler Teardown and Inspections

GeoExchange System Features „ Maintenance and Operations Cons − Quantity of units to maintain − Air filters and drain pans (unitary) − Heat pump locations accessible

„ Maintenance Considerations = Refrigerant 22 vs 410A = Equipment/compressor service life of 19 years = Looping piping service life of 50 + years

18

Environmental Pros and Cons

GeoExchange System Features „ Environmental Pros + More comfortable indoor environment > Each unit operates independently, allowing either heating or cooling to occur as required > Individual Room Control of Heating or Cooling

+ No Make-Up Water for Boiler / Cooling Tower + No Chemical Treatment / Hazardous Materials + Eliminate Carbon Monoxide (CO) Potential + No Vandalism or Security Concerns + Minimal floor area required + Less energy means less natural resources and less pollution

19

GeoExchange System Features „ Environmental Cons − Noise inside building

„ Environmental Considerations = Selection of Circulating Fluids = Temporary disturbance of landscaping = Design for proper indoor air quality

Where does a GeoExchange System Apply?

20

GeoExchange Applications „ New Construction ● Integrate GeoExchange into design ● Optimize system efficiency and costs

„ Retrofit Construction ● Air condition existing non A/C building ● Replace Unit Ventilators or Fan Coil Units ● Minimum disturbance for Historical Preservation

GeoExchange Applications „ Building Type ● Good application: − Single-story – finger plan − Balanced envelope / interior thermal loads

● Weak application: − New well insulated multi-story “box” with high internal loads

● Residential − Excellent application

21

GeoExchange Applications „ Schools are Good Candidates for GeoExchange Systems 9 Retrofit older systems 9 Air conditioning upgrade 9 School building layout normally good for balanced heating/cooling loads 9 Typical classroom good economic size for heat pump 9 Open field area available for Geothermal Heat Exchanger 9 System advantages attractive to schools 9 Schools will be around to enjoy the life cycle cost benefits

GeoExchange Applications „ Domestic Water Heating Applications ● Desuperheater kit to heat domestic water – Standard Option − Cooling Season = Free water heating − Heating Season = High COP water heating

● Water to water heat pumps preheat Domestic Water at a COP of 3.0 – 5.0

„ Water to Water Heat Pump Applications ● Hydronic systems ● Radiant floor systems ● Heating water/chilled water source for Outside Air/ Ventilation Air with conventional air handling systems ● Swimming Pool water heating

22

Radiant Floor Heating Application „ Radiant Floor ● Circulate heated water through piping circuits embedded in floor slab ● Warm Floor radiates heat to the walls, ceiling and other objects ● Water to Water Heat Pumps provide water at an effective temperature

Geothermal System Economics $ First Costs + Energy Costs + Maintenance Costs = Bottom Line

What is the Cost Experience?

23

First Cost Basics „ Building and HVAC System Criteria drive Costs ● ● ● ●

Building Type, Occupancy and Use Thermal Zones and Ventilation Requirements HVAC Equipment Space Allocation Central System vs Distributed / Unitary System

„ Generally, the Geothermal system cost inside the building is less than or equal to conventional system „ Incremental cost of a Geothermal Heat Exchanger vs ● Boiler and Heating Water Pumping systems ● Chiller / Cooling Tower and related Pumping systems ● Condensing Units / Rooftop Units

„ First Cost is greatly influenced by Effective Design

First Cost Considerations „ Manage the Installed Cost ● Reduce the total Heating / Cooling Load − Efficient Building Envelope − Outside Air Loads: CO2 / DCV and Energy Recovery Units − Recognize System Load Diversity

● Field Test for actual Soil Thermal Conductivity ● Organize and Minimize Geothermal System Piping ● Control the Control System Costs ● Experience based evaluation of System Design

24

First Cost Considerations „ Recognize All System Related Cost Savings ● Boiler Stacks and Roof Penetrations ● Boiler Room Combustion Air ● Chemical Treatment, Make Up Water and related equipment ● Structural Cost for Cooling Tower or Equipment Support ● Screen Walls and Fences for Vision, Vandalism, Security ● Machine Room (Refrigerant) Ventilation ● Natural Gas Service Entrance ● Reduced Mechanical Equipment Floor area

First Cost Considerations „ Utility Company Incentives ● $ 0 to $ 600 per ton ● Custom Incentive Programs ● Alternate Rate Schedules ● Check with the Local Utility before Design

„ Financing Options ● Energy Savings or Performance Contracting ● Utility Company Financing

„ Tax Incentives ● Up to $1.80 per SF for 50% better than Energy Standard ● Up to $300 Tax Credit for Residential Geothermal Heat Pumps

25

First Costs – GeoExchange Bore Field „ Unit Cost Summary – 14 Buildings Gross Bore Field Cost

Range

Average

Cost per Square Foot:

$ 1.88 – $ 4.55

$ 3.27 / SqFt

Cost per Ton:

$ 715 – $ 2,817

$ 1,719 / Ton

Cost per Bore:

$ 775 – $ 3,032

$ 1,537 / Bore

Cost per Foot of Bore:

$ 4.43 – $ 12.50

$ 7.83 / BoreFt

„ These are project reported construction costs ● ● ● ●

The costs are not qualified for scope or normalized for conditions Costs do not include Credits for Boilers, Chillers, Cooling Towers Costs do not include Utility Company Incentives Additional Project Cost Information appreciated

First Cost Examples „ West Liberty High School ● New High School 78,000 GSF with 280 tons cooling capacity ● Horizontal Bore Installation Alternate bid ● 112 Horizontal Bores at 500 feet long ● Horizontal Bores stacked two high ● $363,000 for Horizontal Bore Field piped to Building ● $3232 per bore / $6.46 per bore foot ● Vertical Bore arrangement bid at $160,000 more (44% increase)

26

Energy Costs

Energy Costs „ All Electric / Electric Heat Rate Schedule ● Significant Factor for Energy Costs ● Identify the applicable Rate Schedule ● Electric Costs of 4 ¢/KWH electric heat vs. 8 ¢/KWH for winter use ● Some Rates may be applied to the total building electrical use ● Net Heating Energy Costs of $4/MMBTU vs. $12/MMBTU

„ Electrical Demand ● Typical Reduction in Electrical Demand ● Demand Limiting / Load Shedding Opportunities ● Demand may be a significant factor in total electric costs

27

Energy Costs

„ Case Studies – Three Ankeny Elementary Schools ● Actual Site Energy Reduction:

46% to 54% BTU/SF-Yr

● Actual Energy Cost Reduction:

6% to 14% $/SF-Yr

Non Air Conditioned to Air Conditioned

● Energy Cost Avoidance:

20% to 34% $/SF-Yr

Operation and Maintenance Costs

28

Maintenance Costs „ ASHRAE Technical Paper ● “Comparing Maintenance Costs of Geothermal Heat Pump Systems with Other HVAC Systems: Preventive Maintenance Actions and Total Maintenance Costs” A Technical Paper prepared for ASHRAE by Michaela A. Martin, Melissa G. Madgett, and Patrick J. Hughes, P.E.

● Project focus – Lincoln Public School District, Lincoln, NE − 20 School buildings and 4 HVAC System types were evaluated − Maintenance Costs summarized by: > Preventive Maintenance Costs per SF per Year > Repair, Service, and Corrective Action Costs per SF per Year > Total Maintenance Costs per SF per Year

Maintenance Costs „

Lincoln Schools, Lincoln Nebraska

29

Economic Performance „ Bottom Line ● Most Energy Efficient Heating & Cooling System Available ● Comfortable with a High Degree of Owner Satisfaction ● Reduces Energy Cost by 20% to 35% ● Adds 2 – 4% to the Total Cost of New Construction ● Incentives, Credits and Alternate Financing may be Available ● Typical 5 to 10 year payback ● Generally best Life Cycle Costs

„ Each Commercial Facility is Unique

30

Geothermal Heat Pump Technology Thank You…….. Discussion ! ! ! ! Questions ???? Iowa Energy Center / Energy Resource Station Phone: 515-965-7055 [email protected] www.energy.iastate.edu

31

Loading...

Geothermal Heat Pump Systems

Geothermal Heat Pump Systems GeoExchange Technology Curtis J. Klaassen, P.E. Iowa Energy Center Energy Resource Station Geothermal Heat Pump Technol...

2MB Sizes 1 Downloads 0 Views

Recommend Documents

Geothermal Heat Pump Systems - International Ground
Systems Design and Installation Standards manual is intended as a source of precise ... with heat fusion procedures, and

Geothermal Heat Pump and Heat Engine Systems: Theory And Practice
Implemented into an Excel spreadsheet, the model fluid temperature can be calculated at each time step and compared with

Geothermal Heat Pump and Heat Engine Systems: Theory And Practice
open-loop system, fluid, 16, 76, 84, 111, 140, 238, 250–1, 277, 284, 301, 303 optimization, 127–8, 171, 174–5, 205

Sizing geothermal heat pump systems with Geoperformx pipes
Geoperformx pipes. The applications reviewed were a spreadsheet1 developed in Excel by Philippe et al. (2010), EED2,. eQ

Geothermal Heat Pump Design Manual - 15000 Inc
companion guide to McQuay's Catalog 330-1, Water Source Heat Pump Design Manual, which ... operating in cooling. The act

New Geothermal Heat Pump Install & Driveway Heat | GeoExchange® Forum
Oct 11, 2010 - I quite agree that this is likely a poor app for geo given the high load relative to house load. It MIGHT

medium geothermal heat pump
Jun 16, 2015 - Open Access. Download PDF ... Keywords : geothermal heat pumps (GHP); renewable energy sources (RES); eff

Heat Pump Systems with Vertical Ground Heat Exchanger and Uncovered
... Ground-Source Heat Pumps in Dwellings - Analyses of System Performance,” Dissertation, Lund University, Lund, 2009

Heat Pump Efficiency Analysis and Evaluation of Heat Pump Efficiency
Aug 18, 2011 - source heat pumps. These disadvantages result from the large spectrum of op- erating points which further

Factsheet Heat Pump and Heat Recovery Technologies
All refrigeration equipment (i.e. air-conditioners, chillers etc.) can be classified as heat pumps. However, in engineer