geoexchange hydronics
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Transcript geoexchange hydronics
Geo-exchange Central
Systems
Kirk Mescher, PE, LEED® AP
Principal
ASHRAE DAYTONFeb 2010
1
Building Owner
Expectations
Simplicity
Low maintenance
Greater comfort
Efficiency
Environmentally Green
ASHRAE DAYTONFeb 2010
2
“g”eothermal (Ground Coupled)
Systems
The ground is generally moderate temperature
45-65ºF
Low grade energy
Thermal conductivity is not great (the ground is
a poor conductor)
Great deal of MASS
Temperatures are ideal for heat pump
application where heating and cooling energy is
amplified as it is delivered to the building.
ASHRAE DAYTONFeb 2010
3
Design Considerations
Major Advantage to central systems-Diversity
Effective use of Ground Coupling
Pumping efficiency
Utility flexibility
Heating and cooling generation efficiency
Central pumping or diversified
Central heat rejection/addition or diversified
COP and EER considerations
Heating and cooling delivery efficiency
ASHRAE DAYTONFeb 2010
4
Central Systems
Building central systems
Adaptable to “conventional systems”
Chilled Beams
Fan coils/ Unit Ventilators
VAV
Single Zone
Centralized maintenance
Campus central systems
Campus wide diversity
Utility utilization
ASHRAE DAYTONFeb 2010
5
Central system issues
Chilled water delivery
Hot water delivery
120F water
Line loss significance
Cascade refrigeration (180F)
Additional heat transfer
Pumping
42 F water
Additional heat transfer surface
Major component of system efficiency
System EER and COP
Affected by temperatures, system delivery efficiency and pumping
ASHRAE DAYTONFeb 2010
6
Ground Coupling
“the basics”
References
ASHRAE Commercial Geothermal System design
Manual – Rafferty and Kavanaugh
ASHRAE HVAC Simplified- Kavanaugh
GCHPCALC- Loop sizing program –Steve
Kavanaugh
IGSHPA- Various articles
Seminars like this
ASHRAE DAYTONFeb 2010
7
The Players
Site
Owner
Architect
Engineer
Thermal Properties (or well flow) Test Firm
Equipment/Materials Suppliers
Loop Contractor
Driller
Hydrology consultant (open loop)
Mechanical Contractor
Energy Service Contractor (ESCO)
Turn-key GHP contractor
“Experts”, seminar speakers and other suspicious characters
ASHRAE DAYTONFeb 2010
© 2007 Kevin Rafferty, PE
8
Contract Document Requirements
Full description of
Well field layout, piping connections, bedding,
tagging etc.
Well cross section with
Grout specification
Description of drilling strata
Anticipated drilling techniques
Pipe specification and installation requirement
Overall System flow diagram
ASHRAE DAYTONFeb 2010
9
Vocabulary
(engineering speak)
GCHP- Ground Coupled Heat Pump
EER- Energy Efficiency Ratio (Cooling term)
SEER- Seasonal Energy Efficiency Ratio
Effective Cooling Output (BTU)/Energy input (watts)
Does NOT apply to GCHP
Energy Efficiency ratio adjusted for seasonal weather
conditions
COP- Coefficient of Performance (Heating term)
Effective Heating Output (btu)/Energy Input (btu)
WARNING>>>>>>>WARNING>>>>>>WARNING>>>>>>WARNING>>>>>>
When making comparisons make sure your are comparing equal terms.
These terms can be applied to equipment or SYSTEMS. It is best to
compare SYSTEM performance.
ASHRAE DAYTONFeb 2010
10
Heat Pump Performance
Coefficient of Performance (COP) Heating Rating
Q/Wc = the heat delivered (or removal) divided by the work of
the compressor
Energy Efficiency Rating (EER) Cooling Rating
Wc/Q = energy consumption (kW) divided by the heat removed (tons)
ASHRAE DAYTONFeb 2010
11
System Effect on Ground Heat
Exchanger
Energy Sent to the ground=1.26*EFLHc*FLC
Energy absorbed from the ground=.77*EFLHh* FLH
EFLHc-Equivalent Full Load Hours (Cooling)
FLC - Full Load Cooling (Btuh)
EFLHh – Equivalent Full Load Hours (Heating)
FLH - Full Load Cooling (Btuh)
The coefficients in the equation convert the heat pump
capacity to heat rejection (1.26) in cooling and heat
absorption (0.77) in heating. They are representative of a
heat pump with an average EER of 13 and a COP of 3.5.
ASHRAE DAYTONFeb 2010
12
Geoexchange Renewable Energy Concept
1 kW electricity
4 kW Heat
Delivered
3 kW of Geothermal Energy
moved from the Earth
ASHRAE DAYTONFeb 2010
13
Loop Field Temperature Rise
Temp rise= Heat Rejected-Heat Absorbed
ρCp *(Volume)
Consider the annual average ground temperature rise
in limestone (cp = 0.22 Btu/lb-°F, ρ = 165 lb/ft3)
ASHRAE DAYTONFeb 2010
14
Buildings in the Midwest
are heating dominated.
Heat pumps dump 50% more energy (per
delivered ton) during cooling than is removed
for heating.
Occupied buildings need cooling to
temperatures for 30-40 degrees. (<25% of the
total hours are below these conditions)
ARE THEY?
ASHRAE DAYTONFeb 2010
15
How Geo-exchange works
Geothermal
Well Field
Well Field acts
As a battery storing
Heating energy in the summer
Releasing it in the winter
ASHRAE DAYTONFeb 2010
Thermal
Conductivity
16
Real World Loading
Geothermal
Well Field
Heat in Well Field
Is Likely to Increase
ASHRAE DAYTONFeb 2010
Cooling energy>> Heating Energy
17
Hybrid Geo-exchange Systems
Excess Heat
FLUID
COOLER
Cooling
Dominated
ASHRAE DAYTONFeb 2010
Geothermal
Well Field
18
ASHRAE DAYTONFeb 2010
19
Well Field Don’ts
PVC or Copper
•Don’t use vaults
•Don’t require cross trenching
•Piping systems which require balancing
•Don’t use Pure Bentonite Grout
•Place wells closer than 20’OC
•Put valves on wells
•Use the new latest and greatest ground
loop heat exchanger
Bentonite
Grout
ASHRAE DAYTONFeb 2010
20
The new Kids on the Block
Proprietary HX
Beware Grouts with
TC greater than 1.3
Grout hole
Proprietary spiral
turbulated heat
exchanger
Grout
ASHRAE DAYTONFeb 2010
Bottom Line: The bore resistance and
the ground’s resistance to heat flow
greatly diminishes the performance of
enhanced heat transfer systems…
21
Fantastic Improvements
Ground heat exchangers
Coaxial pipe systems
Turbulated Coaxial heat exchangers
Ultra high TC grout systems
2 speed heat pumps
Antifreeze systems with no thermodynamic
penalties
ASHRAE DAYTONFeb 2010
22
Ground Loop
Supplement
Well Field and
Building Purge Assembly
HDPE SDR 11
UNI-LOOP
20’ MIN
Connecting Piping
DR 15.5 HDPE
Thermally
enhanced
grout
Total Field Pressure Loss
20’ H20
ASHRAE DAYTONFeb 2010
23
Today’s
Discussion
ASHRAE DAYTONFeb 2010
What is important?
Power to circulate Fluid
Fluid temperature control.
Flow Control
Piping Systems
24
The Players
in system
efficiency
ASHRAE DAYTONFeb 2010
Piping Network (system head)
Variable Frequency Drives
Water Regulating Valves
Motorized Control Valves
Digital Control Systems
25
Geo Exchange
System Components
VFD
T
PD
Ground Coupled heat exchanger
Piping Network
Pumps
Water source heat pumps
Controls
ASHRAE DAYTONFeb 2010
26
Direct Flow
with 3-way control
VFD
T
PD
ASHRAE DAYTONFeb 2010
Attributes
Control of water temp
Summer and Winter 85/45
Demand Fluid Control
Flow Balance managed by
Regulator Valves
Challenges
System changes with each
device added or subtracted
from duty
Pipe Length/ pressure loss
Control valve pressure
loss/authority
Heat/cool energy
exchange at well field
Central pump must be
sized for connected load
Last Heat Pump can be
short of water flow
27
Reverse Return
with 3 way valve control
VFD
Attributes
Control of water temp
Summer and Winter 85/45
Demand Fluid Control
Flow Regulator volume
control
Equal pipe length to each
heat pump
T
PD
ASHRAE DAYTONFeb 2010
Challenges
System changes managed
with flow regulator valves
Pipe Length/ pressure loss
Pressure loss for valve
control/authority
Heat/cool energy exchange
at well field
Central pump must be
sized for connected load
28
Reverse Return
without loop temp control
VFD
PD
ASHRAE DAYTONFeb 2010
Attributes
Demand Fluid Control
Flow regulator volume
control
Equal pipe length to each
heat pump
Challenges
System changes managed
with flow regulator valves
Pipe Length/ pressure loss
Heat/cool energy exchange
at well field
Central Pump must be
sized for connected load
29
One Pipe Loop
distributed primary secondary loop
sequencer
T
ASHRAE DAYTONFeb 2010
Attributes
Demand Fluid Control
Secondary pump
flow control
Little loop temp control
Unit by unit diversity
No flow regulators
Low system pump head
Primary pump can be sized
for BLOCK load COnditions
No drive/pump/static
control head inefficiency
Challenges
Temperature control
Pipe Length/ pressure loss
Last Heat pump will have
warmer/cooler water
30
Heat Recovery
Anyone????
sequencer
Attribute
One pipe loop allows heat
pumps to recover energy
from the other units on the
system.
Cooling units add heat to
the loop, heating units
extract heat…
T
ASHRAE DAYTONFeb 2010
It doesn’t take VRF to have
heat recovery.
31
Lakeland Area Community College
Main loop suitable for:
10” Pipe (2000 gpm 800 tons)
12” pipe (3500 gpm 1450 tons)
SYSTEM DIAGRAM
S1
S2
12ºF
TC
TC
TC
TC
12ºF
Future GCHX
S2
S1
S2
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32
12ºF
S1
Central Plant Schematic
Chiller
ASHRAE DAYTONFeb 2010
33
Ground Coupling Connection
Hot and Chilled water are hydraulically connected
Hot and Chilled are thermally isolated
System is capable of rejecting excess heat
System is capable of imposing additional cooling load
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Load Control
4 pipe to 2 pipe changeover control is available
True 4 pipe is available
Load flow rate is independent of loop flow
2 pipe coils are generally larger heat transfer surfaces
No pressure penalty for additional coil surface
ASHRAE DAYTONFeb 2010
35
Cascade Chillers
for High Temp
Chiller
Chiller
ASHRAE DAYTONFeb 2010
36
Geo-exchange System Efficiency
Efficient
Heat pumps
Low Loop
Pumping
Power
ASHRAE
DAYTONFeb 2010
Well
Designed
Ground Loop
© 2007 Kevin Rafferty, PE
37
System efficiency
Unitary delivery
No intermediate heat transfer
Single zone
Intermediate heat transfer
Additional pumping
VAV
Intermediate heat transfer
Additional pumping
BTU delivery through low density source
ASHRAE DAYTONFeb 2010
38
System Inputs
Input Data
Building Name Oregon Etenire
Building Area
42200 SQ. FT.
COOLING
83 TONS
HEAT
533.1 MBTUH
Location Rockford Illinois Data
Summer design temp
Wetbulb
Rel Humidity
Specific Humidity
Summer Design enthalpy
75
63
51.6
66.8
28.4
F
F
% RH
Grains
BTU/#
Setback
WinterDesign Temp
Wet Bulb
Rel Humidity
Specific Humidity
Winter Design enthalpy
70
54
33.6
36.5
22.5
F
F
% RH
Grains
BTU/#
Setback
Economizer
Humidification
ERU
ERU Efficiency
0
0
0
0.7
Geothermal One Pipe System Output
Loop Head 35
Equipment Head 12
Air TD Cooling 20
Air TD Heating 30
SP 0.75
47.9
77.9
37.9
40%
Occupancy
Minimum Ventilation
min vent
Occupancy Ventilation
78 F
occupant vent
Total Ventilation
338
0.04
1688
10
3376
5064
Persons
cfm/sq. ft.
cfm
CFM/person
cfm
cfm
Lighting
Power
Occupied
Building UA
1.3
0.5
50
4942
W/ft^2
w/ft^2
Hrs/week
Btuh/F
68 F
FUEL COST
Fuel Efficiency
Ele rate
(1-yes, 0-no)
(1-yes, 0-no)
(1-yes, 0-no)
(0-1.00)
Deep Earth Temp
Summer Water Temp
Winter Water Temp
Air to wire efficiency
Unit selection 1- WF Envision
1
2- WF Premier
3- FHP ES
4- FHP EV
5- Bard QW
CALCULATION OF BUILDING UA
# of Floors
1
Roof Area 42200
2813
R Value
15
Wall Area 12326
896
R value
11
Glass%
20
Area
2465
1233
U Value
0.5
Overall UA
Cooling SF
Heating SF
Geothermal 2 Pipe Heat Pump Output
Air TD Cooling 20
Air TD Heating 30
SP 0.75
Loop Head 62
Min Head Control 30
15 $/mcf
0.8
0.08 $/kwh
4942
1.1
1.20
40% Air to wire efficiency
ASHRAE DAYTONFeb 2010
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Typical system performance
Building Name Oregon Etenire
Building Area
42200 SQ. FT.
COOLING
83 TONS
HEAT
666.4 MBTUH
HeatPump Selection 1- WF Envision
Location Rockford Illinois Data
507 Sq Ft/Ton
15.8 BTU/Sq. Ft
Base Electrical Usage
Lights and Other Electrical Usage
Annual Energy Cost
196323.65 Kwh
$15,705.89
$0.37 $/ft^2
Geothermal One Pipe System Output
HVAC Energy Use
Annual HVAC Cost
Other Energy Use
Total Annual Energy Cost
106379.0
$8,510.32
$0.20
$0.37
$0.57
$24,216.21
Kbtu/sq. ft./yr
24.48
Other Energy Use
Building Energy Usage
Total Annual Energy Cost
ASHRAE DAYTONFeb 2010
107328.2
$8,586.26
$0.20
$0.37
$0.58
$24,292.15
Gen Kbtu/sq ft
75.32
KWH
$/ft^2
$/ft^2
$/ft^2
Geothermal 2 Pipe Heat Pump Output
HVAC Energy Use
Annual Energy Cost
Demand KW 76
Total Demand KW 134
System EER 16.34
System COP 4.01
Kbtu/sq. ft./yr
24.56
Gen Kbtu/sq ft
75.55
KWH
$/ft^2
$/ft^2
$/ft^2
Total Demand KW 132
System EER 16.76
System COP 4.31
10 year totals
Energy
$5.74
Maintenance $2.27
$8.01
10 year totals
Energy
$5.76
Maintenance $2.27
$8.03
40
VAV System
Performance
VAV with terminal reheat
Chiller TD 12
Boiler TD 20
Loop Head 65
Fan Static 4.5
Fan Control Static 1.5
Air to wire efficiency varies with Inverter load
VAV with terminal reheat
Total Gas Usage
HVAC Energy Use
1390.9 MCF
133818.3 KWH
Other Energy Use
Building Energy Usage
Total Annual Energy Cost
ASHRAE DAYTONFeb 2010
$20,863.61
$10,705.47
$31,569.08
$0.75
$0.37
$1.12
$47,274.97
Kbtu/sq. ft./yr
60.48
Annual Gas Energy $
Annual Electrical Energy $
Total
$/ft^2
$/ft^2
Total Demand KW
$/ft^2
System EER
System COP
Gen Kbtu/sq ft
85.44
10 year totals
Energy $11.20
Maintenance $6.52
$17.72
188
7.30
0.58
41
Everything should be made as simple as possible,
but not simpler. ~Albert Einstein
ASHRAE DAYTONFeb 2010
42
ASHRAE 90.1
Engineering standard of care for system
efficiency
Is generally an equipment standard
System Efficiency
Change is in the air – Energy Use Targets
ASHRAE DAYTONFeb 2010
43
Standard 90.1 - HVAC Equipment
Loophole #1
Regulates components but no limits on how
many components are used
System efficiency is unregulated
No method for calculating or rating minimum
efficiencies of built up systems
Equipment efficiency standard, resulting systems
are NOT equal Efficiency
ASHRAE DAYTONFeb 2010
44
The HVAC Equivalent of an SUV
Air Cooled Chiller with FPVAV
kW = 1.1+0.07+0.07+0.15+0.3+0.16 = 1.85
tons = 1.0-0.03-0.02-0.09-0.05 = 0.81
kW/ton = 2.27
EER = 5.3
To
Room
Compressors
Return
~55ºF
Hot Water or
Electric Coil
VAV
Terminal
Return Air Fan
VAV
Terminal
Return
Air
Re-Circulated
Air
Terminal
Terminal
Chilled Water Coil
VS Fan
Motor
VAV
VAV
Terminal
0.16 kW
-0.05 tons
Chilled
Water
Exhaust Air
VAV
Terminal
Supply
Air
VAV
Supply
~45ºF
Air-Cooled Chiller
0.15 kW
-0.03 tons
Series Fan Powered
VAV Terminal
Chiller
Pump
Chiller (Evaporator)
Air Valve
Re-Circulated
Room Air
1.1 kW
+1.0 ton
Condenser Fans
Condenser
Primary
Air
Drive
0.07 kW
0 tons
Supply Air Fan
Chilled
Water Pumps
Mixed Air
0.30 kW
-0.09 tons
Filter
Inverter
Drive
0.07 kW
-0.02 tons
Ventilation
Air
Chilled Water Return
Chilled Water Supply
Building
Loop Pump
VAV Terminal Fans
Central AHU with Variable-Speed Drive Fan Motor
ASHRAE DAYTONFeb 2010
Content Courtesy of Steve Kavanaugh
45
HVACSysEff07.xls
Air Cooled Chilled Water System
Variable Air Volume
Fan Powered Terminal
Override Default Values (d) in Input Column
1
KWperTonACC
Std. 90.1
Input
d
1.14
kW
1.13
Fan HP
Ton hp/ton 1000cfm
1.00 1.366
2
TSPSupply
MotorEffSup
FanEffSup
CFMperTonSup
d
d
d
d
4
90
65
400
0.32
-0.09
0.39
0.97
3
TSPReturn
MotorEffRet
FanEffRet
Exhaust%
d
d
d
d
2
90
65
20
0.16
-0.04
0.19
0.48
4
ChillWtrHead
MotorEffChW
PumpEffChW
GPMperTonChW
d
d
d
d
100
90
65
2.4
0.08
-0.02
0.09
5
CondWtrHead
MotorEffCW
PumpEffCW
GPMperTonCW
d
d
d
d
0
90
65
3
0.00
0.00
6
KWperTonCTower
d
0.065
0.07
0.08
7
KWperTonTermFan
d
0.18
0.18
-0.05
S=
1.94
2.42
5.0
1.45
0.80
kW/Ton =
EER =
0.16
0.39
1.85
COP =
Chiller kW/ton based on 44 F Chilled Water & 95 F outdoor air temperature
Override Temperature Default Values (d) below (Condenser flow adjusted above)
Input
CorFac
LWTempCHW
d
44
1.00
OATemp
d
95
1.00
ASHRAE DAYTONFeb 2010
46
Content Courtesy of Steve Kavanaugh
The HVAC Equivalent of an SUV
Air Cooled Chiller with FPVAV
kW = 1.1+0.07+0.07+0.15+0.3+0.16 = 1.85
tons = 1.0-0.03-0.02-0.09-0.05 = 0.81
kW/ton = 2.27
EER = 5.3
To
Room
Compressors
Return
~55ºF
Hot Water or
Electric Coil
VAV
Terminal
Return Air Fan
VAV
Terminal
Return
Air
Re-Circulated
Air
Terminal
Terminal
Chilled Water Coil
VS Fan
Motor
VAV
VAV
Terminal
0.16 kW
-0.05 tons
Chilled
Water
Exhaust Air
VAV
Terminal
Supply
Air
VAV
Supply
~45ºF
Air-Cooled Chiller
0.15 kW
-0.03 tons
Series Fan Powered
VAV Terminal
Chiller
Pump
Chiller (Evaporator)
Air Valve
Re-Circulated
Room Air
1.1 kW
+1.0 ton
Condenser Fans
Condenser
Primary
Air
Drive
0.07 kW
0 tons
Supply Air Fan
Chilled
Water Pumps
Mixed Air
0.30 kW
-0.09 tons
Filter
Inverter
Drive
0.07 kW
-0.02 tons
Ventilation
Air
Chilled Water Return
Chilled Water Supply
Building
Loop Pump
VAV Terminal Fans
Central AHU with Variable-Speed Drive Fan Motor
ASHRAE DAYTONFeb 2010
Content Courtesy of Steve Kavanaugh
47
Packaged HVAC Systems
Minimum Efficiency
EER 9.8
ASHRAE DAYTONFeb 2010
48
Pumping Power
The Guiding Light
Pumping Power Benchmarks
Pumping
Pwr /Clg
Cap. Watts
Input/ton
Pumping
Pwr / Clg
Cap. Pump
Hp/100
tons
Grade
Allowable
Pump Head
(ft) w/60%
Eff Pump
Min Max
50 or Less 5 or less
A- Excellent
47.5
50-75
5-7.5
B- Good
47.5 71.3
75-100
7.5-10
C- Mediocre
71.3
95
100-150
10-15
D- Poor
95 143
>150
>15
F- BAD
143
Pump Heads are calculated at 2.5 GPM/ton
for 3 gpm / ton reduce values by 17%.
ASHRAE DAYTONFeb 2010
49
Why is pumping power important?
Pump Effect on EER
HP/100 tons
watts HP/watts Total Watts Effective EER
5.0
3730
66667
70397
17.0
7.5
5595
66667
72262
16.6
10.0
7460
66667
74127
16.2
15.0
11190
66667
77857
15.4
20.0
14920
66667
81587
14.7
25.0
18650
66667
85317
14.1
HP watts based on EER 18
ASHRAE DAYTONFeb 2010
%loss
5.30%
7.74%
10.06%
14.37%
18.29%
21.86%
50
Effect of Pumping on Performance
System EER
UNIT EER
Variable Flow EER
One Pipe EER
UNIT COP
Variable Flow COP
One Pipe COP
30
7
6.5
25
6
5.5
20
15
4.5
4
10
3.5
3
5
2.5
0
2
30
40
50
60
70
80
90
100
110
120
TEMP (F)
ASHRAE DAYTONFeb 2010
51
COP
EER
5
Effect of Temperature
control on Performance
VFD
T
PD
System EER
UNIT EER
Variable Flow EER
UNIT COP
Variable Flow COP
30
7
6.5
25
6
5.5
20
15
4.5
4
10
3.5
3
5
2.5
0
2
30
ASHRAE DAYTONFeb 2010
40
50
60
70
80
90
100
110
120
TEMP (F)
52
COP
EER
5
Effect of Temperature
control on Performance
Variable Flow System EER
COOLING
CAPACITY
(TC)
UNIT
EER
30.7
33.7
36.4
36.2
36.7
35.8
33.7
32.7
29.8
27.6
26.7
26.9
26.5
24.2
22.3
19.8
16.9
14.8
12
10.1
FLUID ADJUSTED UNIT
FAN PUMP (1,2)
EWT
TC
WATTS WATTS
WATTS
30
40
50
60
70
80
90
100
110
120
29.7
32.7
35.4
35.2
35.7
34.8
32.7
31.7
28.8
26.6
1150
1253
1374
1496
1646
1808
1994
2209
2483
2733
287
287
287
287
287
287
287
287
287
287
TOTAL
WATTS
SYSTEM
EER
1632
1735
1856
1978
2128
2290
2476
2691
2965
3215
18.2
18.9
19.1
17.8
16.8
15.2
13.2
11.8
9.7
8.3
TOTAL
WATTS
SYSTEM
COP
2360
2399
2444
2490
2543
2592
2646
3.1
3.5
3.9
4.3
4.7
5.0
5.3
195
195
195
195
195
195
195
195
195
195
Variable Flow System COP
HEATING
CAPACITY
(TH)
UNIT
COP
24.1
28.0
31.6
35.5
39.6
43.0
46.6
3.76
4.28
4.72
5.18
5.63
5.97
6.31
FLUID ADJUSTED UNIT
FAN PUMP (1,2)
EWT
TH
WATTS WATTS
WATTS
30
40
50
60
70
80
90
25.1
29.0
32.6
36.5
40.6
44.0
47.6
1878
1917
1962
2008
2061
2110
2164
287
287
287
287
287
287
287
ASHRAE DAYTONFeb 2010
(1) Pump power is increased to compensate for FCV, motorized valve and strainer.
195
195
195
195
195
195
195
(2) 10' is added to the system head to accommodate unit PD variation and pressure control setpoint.
53
Variable Speed
Pumping
1750 RPM
ASHRAE DAYTONFeb 2010
54
Motor and Drive Efficiency
Inverters do not provide
Linear energy consumption
ASHRAE DAYTONFeb 2010
55
Variable Speed
Pumping
Efficiency (Motor, Drive & Pump)
70
60
Efficiency %
50
40
30
20
10
0
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Load
ASHRAE DAYTONFeb 2010
56
System Calculations
Variable Speed
Variable Flow System
% load on system
10
20
Ground loop pressure loss
1.8
1.8
Building dist head loss
1.35
1.35
equipment head
35.93
35.93
Addition for control setpoint
5
5
Total Pump Head Ft.
44.08
44.08
Flow
54.3
54.3
Calculated Pump HP (100%)
0.5
0.5
% loaded
17.4%
17.4%
Calculated Pump Eff
42.6%
42.6%
Pump Mech HP
1.4
1.4
Selected Pump HP
6
% load on Motor
23.6%
23.6%
VFD & Motor Efficiency
37.8%
37.8%
HP load
3.7
3.7
Power Consumption KW
2.8
2.8
System power is limited to a 30% flow minimum.
Pump and Motot Efficiencies are assumed to be constant.
ASHRAE DAYTONFeb 2010
30
1.8
1.35
35.93
5
44.08
54.3
0.6
17.4%
42.6%
1.4
40
3.2
2.4
35.93
5
46.53
72.4
0.9
24.5%
50.5%
1.7
50
5
3.75
35.93
5
49.68
90.5
1.1
32.7%
56.1%
2.0
60
7.2
5.4
35.93
5
53.53
108.6
1.5
42.3%
59.4%
2.5
70
9.8
7.35
35.93
5
58.08
126.7
1.9
53.5%
60.9%
3.1
80
12.8
9.6
35.93
5
63.33
144.8
2.3
66.7%
62.0%
3.7
90
16.2
12.15
35.93
5
69.28
162.9
2.8
82.1%
64.3%
4.4
100
20
15
35.93
5
75.93
181
3.5
100.0%
65.0%
5.3
23.6%
37.8%
3.7
2.8
28.1%
37.8%
4.5
3.3
33.7%
48.2%
4.2
3.1
41.2%
59.8%
4.1
3.1
50.9%
71.7%
4.3
3.2
62.3%
81.6%
4.6
3.4
73.9%
88.0%
5.0
3.8
89.0%
92.0%
5.8
4.3
Low speed conditions will adversely affect the mechanical efficiency.
57
System Calculations
One Pipe
One Pipe System (Single Speed)
% load on system
10
20
30
Ground loop pressure loss
11.25
11.25
11.25
Building dist head loss
8.4
8.4
8.4
Total Pump Heaad Ft.
19.7
19.7
19.7
Flow
135.8
135.8
135.8
Calculated Pump HP
2.7
Selected Pump HP
1.5 (2 required)
Pump power at condition KW
1.2
1.2
1.2
% loaded
79.8%
79.8%
79.8%
Power Consumption KW
0.9
0.9
0.9
Circulator Power KW
0.2
0.5
0.7
Total Pumping Power KW
1.14
1.38
1.62
1- Must have this pressure available throughout the system)
2- 2 psi minimum
ASHRAE DAYTONFeb 2010
40
11.25
8.4
19.7
135.8
50
11.25
8.4
19.7
135.8
60
11.25
8.4
19.7
135.8
70
11.25
8.4
19.7
135.8
80
11.25
8.4
19.7
135.8
90
20
15.0
35.0
181.0
100
20
15.0
35.0
181.0
1.2
79.8%
0.9
1.0
1.86
1.2
79.8%
0.9
1.2
2.11
1.2
79.8%
0.9
1.5
2.35
1.2
79.8%
0.9
1.7
2.59
1.2
79.8%
0.9
1.9
2.83
2.8
94.5%
1.1
2.2
3.24
2.8
94.5%
1.1
2.4
3.48
58
Parallel Pump Curve
Parallel pump
operating point
3.1 HP (3.8 HP/100 tons)
Individual pump
operating point
1.75HP (2.1 HP/100 tons)
Single pump and Parallel pump operation allows for greatly
reduced pump horsepower usage during normal operation.
No speed control is required.
200 gpm @ 40’ Parallel Pumps
165 gpm @27’ Single pump
ASHRAE DAYTONFeb 2010
59
Pumping Power
Performance
VFD
1 Pipe
100.0%
% Power of Peak Power
80.0%
60.0%
40.0%
20.0%
0.0%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
% System Load
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60
Effect of Pumping
on EER
VFD
One Pipe
18
17
16
15
EER
14
13
12
11
10
9
8
0
20
40
60
80
100
120
% load
ASHRAE DAYTONFeb 2010
61
Typical
System
By limiting the flow at a
particular unit, Pressure
regulating valves fix the
unit pressure loss to that
of the highest pressure
loss of the system.
i. e. to balance this system
all heat pumps will
effectively operate at 28’
tdh.
ASHRAE DAYTONFeb 2010
HEAT PUMP UNIT SCHEDULE
MARK
HP-01
HP-02
HP-03
HP-04
HP-05
HP-06
HP-07A
HP-07B
HP-8
HP-9
HP-10
HP-11
HP-12
HP-13
HP-14
HP-15
HP-16
HP-17
HP-18
HP-19
HP-20
HP-21
HP-22
HP-23
HP-24
HP-25
COOLING
WATER
CAPACITY (BTH)
FLOW
TOTAL
SENSIBLE (GPM)
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
29,940
20,550
6.5
29,940
20,550
6.5
34,308
25,840
9.0
60,032
45,220
15.0
60,032
45,220
15.0
40,140
30,240
9.0
8,420
6,340
2.0
15480
11520
4.0
10,640
8,010
2.5
8,420
6,340
2.0
8,420
6,340
2.0
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
35,080
26,760
7.5
10,640
8,010
2.5
35,080
26,760
7.5
H.P. Connection
WPD
HEAD
(FT)
(FT)
12.7
27.7
12.7
27.7
12.7
27.7
12.7
27.7
12.7
27.7
12.7
27.7
6.0
21
6.0
21
10.2
25
12.5
28
12.5
28
6.6
22
5.5
21
4.9
19.9
8.5
23.5
5.5
21
5.5
21
12.7
27.7
12.7
27.7
12.7
27.7
12.7
27.7
12.7
27.7
12.7
27.7
12.7
27.7
8.5
23.5
12.7
27.7
1. Additional Head includes 2 psi for flow control, strainer,
5' for piping and control valve
62
One Pipe Systems
Allows for the integration of different loads on a
single loop.
Heating systems directly supplement cooling
systems and vice versa.
The system does not change with load.
Pumping is matched to unit flow requirements.
Loop field receives flow at all times, allowing for
temperature moderation throughout the field.
ASHRAE DAYTONFeb 2010
63
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ASHRAE DAYTONFeb 2010
Questions
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