climatemaster geothermal what, when, where, & how
TRANSCRIPT
ClimateMasterGeothermal
What, When, Where, & How
What IsWhat Is Geothermal?Geothermal?
Boiler/Tower Boiler/Tower SystemsSystems
Ground-SourceGround-Source(Geothermal)(Geothermal)
Several Variations of Geothermal
Vertical Closed LoopHorizontal Closed LoopHybrid (Geo and Tower/Boiler)Lake Closed LoopClosed to the AquiferStanding Column Well
Vertical Loop System
Verticals
One Pair Two Pair Series/Parallel One Pair
Avg
De
pth
Avg
De
pth
Avg
De
pth
When Loops areshallower than
one ton per loop
Vertical Loops
• 3/4” pipe - One vertical bore per ton. One circuit and 3 gpm flow per ton.
• Many areas require bentonite grouting• Some locales restrict drilling• Bore per ton
– Cold climates 150 ft per ton– Warm climates 230 ft per ton
Horizontal Loop System(Slinky shown)
Horizontal Loop Types
2 ft 2 ft
2 ft
2 ft
2 ft
Back-Hoe LoopsTwo-Pipe Four-Pipe Six-Pipe
1 ft
Trenched Loops
2 ft
Two-Pipe Four-Pipe Extended Slinky
Horizontal Loops
• Limited tonnage due to land area• Backhoe or trench excavation. In areas with
any rock typically backhoe only.• 1 circuit and 3 gpm flow per ton w/ 3/4” pipe• Pipe per ton
– Cold Climates - 400 to 1000 ft– Warm Climates - 700 to 1800 ft
Ground Source - Closed Loops
• Benefits– Lower maintenance– No water requirements
• Hurdles– Requires land space– First cost
Ground Loop
• 3 gpm flow per ton of cooling• 1 circuit or flow path per ton of cooling w/ 3/4” loop pipe• Loop Temperatures
– 40 - 90 deg F
Hybrid Systems
Ground Loop/TowerGround Loop/BoilerBenefits:
– Off Peak Operation
– Low First Cost
Hybrid Loops
Lake Loop System
300 ft slinky coilper ton
4 ft between coils
ConcreteBlocks for
weight
Nylon Cable Tiesto secure blocks
300 ft coil per tonseparated by scrap
pipe
Traditional Coiled Pond Loop- Southern Climates
High Efficiency Slinky/Matt PondLoop - Northern Climates
Heavy Duty PlasticSafety matting
8-10 Bricks forweight
Reverse ReturnHeader
Nylon Cable Tiesto secure Netting
and bricks
3 foot separation
Pond Loops
• Least expensive ground loop• Minimum 300 ft2 per ton and 9 feet deep• In north need ice cover for operation (no
aeration). Utilizes 39 degF water temp.• Pond should be within 300’ of structure• 300 ft Pipe per ton
Closed to the Aquifer Systems
Ground Water - Plate Frame HX • Benefits
– Lower first cost– No land requirement– Isolated internal loop via HX
• Hurdles– Requires annual HX maintenance– Requires injection well– Typically used only with more than 4 total units
Standing Column Well
Ground Water - Direct Use
• Benefits– Lowest first cost– No land requirement
• Hurdles– Requires clean water and more maintenance– Getting rid of water can be difficult– Larger pump and pressure tank– Typically used only with 3 or less total units
Heat of extraction/rejection
Moving Heat to Water or Air
water refrig airorororor
Heat of extraction
HEATING
water refrig air
WORK 1.08 kw=3.680 kbtu/hr
11.6 kbtu/hr 15.3 kbtu/hr
COP = 15.3/3.68 = 4.15
Heat of rejection
COOLING
water refrig air
work
15.2 kbtu/hr
0.95 kw=3.2 kbtu/hr
12.0 kbtu/hr
EER = 12.0/0.95 = 12.6
Refrigeration Circuit Overview
Compressor
ExpansionDevice
To Loop Source
ReversingValve
AirCoil
Suction
DischargeCoax
Refrigeration Circuit OverviewCooling Mode (GS036)
Compressor
ExpansionDevice
To Cooling Tower
ReversingValve
AirCoil
Suction
DischargeCoax
155 F218 psi
53 F
80 F 60 F
62 F
90 F
60 F76 psi
100 F
92 F 9gpm
a) Lvg air coil temp is lower than ent air coil temp is due to pressure drop through air coil.a) Lvg air coil temp is lower than ent air coil temp is due to pressure drop through air coil.b) Suction temp at compressor is higher than lvg air coil temp because vapor continues b) Suction temp at compressor is higher than lvg air coil temp because vapor continues to superheat as it travels back to compressor.to superheat as it travels back to compressor.
Refrigeration Circuit OverviewHeating Mode (GS036)
Compressor
ExpansionDevice
To Boiler
ReversingValve
AirCoil
Suction
DischargeCoax
168 F248 psi
168 F
70 F 107 F
96 F
70 F
66 F86 psi
62 F
59 F 9gpm
62 F
How didHow did GeothermalGeothermal
Gain MomentumGain Momentum??
HistoryBehind
Geothermal
Late 70’s-Early 1980’s
• Energy crisis: Fossil fuel shortages and price shocks
• Dependence shifts to electricity• Opportunity builds for geothermal technology• Technical competence for geothermal water
source heat pumps develops in the industry
Mid 1980’s
• Electric utilities experiencing “peak demands”• DSM (demand side management) becomes a
strategic planning tool• Extensive monitoring reveals geothermal
efficiency and market potential• Geothermal becomes recognized as DSM
planning tool
Late 1980’s
• Performance Standards established for geothermal systems
• Support grows from regulators, research groups and utilities
• Substantial performance in utility DSM programs
• A proven technology competitive with conventional fuels
Early 1990’s
• Geothermal systems increase in performance and functionality
• EPA, DOE, EPRI (Electric Power Research Institute), NRECA (National Rural Electric Cooperative Assoc), EEI (Edison Electric Institute) recognize potential for geothermal
• Utility geothermal DSM programs begin implementation
Mid 1990’s
• Geothermal recognized as key technology to reduce greenhouse gases
• EPA and DOE release reports confirming industry growth potential
• Government, utility, and industry consortium formed to assist in the development of the geothermal market
Late 1990’s-Year 2000
• Geothermal becomes recognized as a major renewable energy source on an international scale
History of Ground Source Heat Pumps Installations
• Based upon water source heat pump from Florida of 1950’s
• Ground loop development using iron and copper loops 1930’s and 40’s. PB and PE pipe made viable in late 1970’s.
• Three regions of development in 1979:– OSU - J. Bose, J. Partin, G. Parker– Ft Wayne, IN - Dan Ellis– Ontario - Dave Hatherton
Antifreeze Materials
• Methanol - least expensive and good heat heat transfer
• Ethanol - More expensive and best heat transfer
• Propylene glycol - non-toxic and expensive, but lowest heat transfer
Pipe and Fittings
Pipe and Fittings Material
• High Density polyethylene (HDPE )pipe developed for natural gas distribution industry
• Socket or Butt heat fusion joints are stronger than the pipe wall itself
• 3/4, 1, 1-1/4, 1-1/2, and 2” sizes common• Coils and straight lengths• Many fittings available in tee’s, elbow’s, and
couplings
Loop Design
Loop TerminologyHeader
Supply/ReturnLines
Loop/Heat Transfer Field
Loop Terminology (cont.)
Manifold
Supply/ReturnLines
To Earth Loop
To Building
Supply/Return Isolation Valves
Loop Design
• Loop style and total trench/bore length obtained from software design
• Goal is 2.5 - 3 gpm flow per ton of capacity (minimum of 2.25 gpm)
• Loop circuiting is designed for:– Low pressure drop– Good heat transfer
• Headers are piped in reverse return to even out pressure drop in parallel circuits
Pumps
• Option 1 - Redundant Alternate - Size single pump to handle complete circulation install duplicate redundant pump in parallel and control alternately
• Option 2 - Redundant Staged - Install two pumps in parallel that can handle load and stage them with alternating controls
• Option 3 - Variable speed pumps with solenoids at each unit
• Option 4 - Distributed pumping - Install pumps at each heat pump with single pipe system and continuous circulation
Circuit Design rules
• 1 circuit per ton of capacity in 3/4” • 2.5 - 3 gpm per ton of capacity
Header Design
Circuit 4 Circuit 3 Circuit 2
Cir
cuit
1
1 1/4" IPS PE Pipe
3/4" IPS PEPipe
1 1/4” x 1 1/4" x 3/4"IPS PE Tee
Sup
ply/
Ret
urn
Line
11/4" x 3/4" x 3/4"IPS PE Tee
3/4" x 3/4" x 3/4"IPS PE Tee
3/4" IPS PEPipe
3/4" IPS PEPipe
3/4" IPS PEPipe
Circuit 5
Design Do’s and Don’ts
• Design air scoop/trap between building and earth loops to entrap air stemming from wshp maintenance
• Utilize Mechanical room or outside pit to house manifold of supply/return lines with individual shut-offs and main loop to building
• Ensure equipment is rated for temperature range of loop WLHP, GWHP or GLHP
• In hybrid design size loop for heating load and tower for extra cooling required
Flushing
• Flush exterior loop first using system pumps. • Flush supply/return one at a time.• Flush interior loop with exterior isolated so as
not to move air to earth loop
Antifreeze
• Antifreeze to 15 deg F below coldest loop temperature expected
• Always add alcohols below water level to reduce fumes
• Check antifreeze concentrations using the specific gravity charts
EquipmentEquipment
Components Allowing Geothermal
Copeland UltraTech™two-stage unloadingscroll compressor
Oversized lanced fin / rifled tube refrigerant-
to-air coil
Insulated Refrig Circuit
Large coaxial refrigerant-to-water
heat exchanger Bidirectional TXV
Ground source versus air source
• Water has better heat transfer than air• Improved low temp heating capacity• Lower peak demand• Outdoor ambient conditions, damage, and
vandalism• Noisy and unsightly outdoor unit• Better dehumidification• Higher efficiencies
ARI Ratings Summary
• ARI/ISO/ASHARE 13256-1 Ground loop heat pump– Based upon typical extreme loop temperatures– Htg 32 degF and clg 77 degF
Lincoln, NE school district compared leading systems for 3 new schools:
Comparative Analysis of Life-Comparative Analysis of Life-Cycle Costs of Heat Pumps Cycle Costs of Heat Pumps
System 150 Tons $/sq. ft.
Geothermal WLHP $1,021,257 $14.66
Air Cooled Recip Chiller/VAV $1,129,286 $16.21
Water Cooled Cent Chiller/VAV $1,164,268 $16.71
• Note: Air Cooled Chiller is 1kw/ton. Water Cooled Chiller is 0.6kw/ton. Vertical Bore Loop Field cost is $2.50 included in the Geo WLHP cost.
Garrett Office BuildingsEdmond, Oklahoma
Geothermal Building20,000 Sq. Ft.
VAV Building15,000 Sq. Ft.
Floor 2 Conference
Floor 2 Private Office
Floor 2 Open Office Space
Geothermal BuildingFloor 2 Heat Pump Zoning
8
9 10
11
12
13
1415
16
HP-8 HP-11
HP-15 HP-14
HP-13
HP-12
HP-9,10
Loop Field Overview
Geothermal BuildingLoop Field Site Plan
LoopField
Details
2” PE Zone Supply Header - Return Similar3/4” PE bore piping back toheader
Notes:- 40 bores on 20 foot centers each with 3/4” PE pipe- Short header manifold in center of each loop zone of 10 bores- Each bore must have the same overall pipe length for balanced flow
(Coil excess piping in the header trench)- Loop zone supply and returns done in same fashion- Bores must be grouted when completed
Short headerlocation
Typical bore250 ft deep
Geothermal Mechanical
Room
GeothermalMechanical
Room
3” Copper
2” PE typical
2” PE typical
Heat PumpSupply
Heat PumpReturn
Expansion
AirSeparator
CWS
125 GPM @ 70’PumpsPrimary/Standby
Ground LoopSupply
Ground LoopReturn
Charging
Bypass
Pressure Reducer/Relief
Backflow Preventor
3/4”Air Vent
Floor 1 Heat Pump Piping
Garrett Office BuildingsHighway View
Geothermal BuildingRoof View
VAV BuildingRoof View
VAV BuildingCentral Air Handler
VAV BuildingAir-Cooled Condensing Unit
VAV BuildingBoiler Room
Month Gas Mcf Elec kWh Gas Mcf Elec kWhJan-00 36.2 12,400 0.0 9,920 Feb-00 21.0 14,720 0.0 10,880 Mar-00 6.9 13,600 0.0 9,960 Apr-00 4.3 15,760 0.0 10,120 May-00 3.5 17,920 0.0 11,600 Jun-00 4.2 18,560 0.0 12,400 Jul-00 3.2 21,280 0.0 13,120 Aug-00 3.2 23,520 0.0 14,480 Sep-00 3.2 18,720 0.0 11,120 Oct-00 11.2 16,080 0.0 9,840 Nov-00 21.9 12,720 0.0 10,360 Dec-00 69.4 13,600 0.0 13,600 Total 188.2 198,880 0.0 137,400
$ Cost 1,882 $ 17,899 $ $ 10,992 $
$/ft^2
VAV 15,000 ft^2 Geothermal 20,000 ft^2
1.32 0.55
Garrett Office Buildings 2000 Energy Consumption
Garrett Office Buildings2000 Energy Consumption Profile
Garrett Office BuildingsInstallation Costs
• Geothermal System circa 1998– Complete exterior loop, mechanical room,
interior PE piping, flushing and unit startup, heat pumps, duct work, exhausts, MUA system, timeclock-based controls
– $128,700 ($2,574 per ton)
• VAV System circa 1987– air-cooled condenser, VAV air handler, boiler,
VAV boxes with reheat coils, economizer, electronic controls
– $100,000 ($2000 per ton)– costs per building owner do not include structural
or architectural
ClimateMasterGeothermalHeat Pumps