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1
“Condenser Water Heat
Recovery"
Julian de Bullet
ASHRAE Distinguished Lecturer
V.P. Business Development
FAFCO Thermal Storage Systems
PLEASE MUTE CELL PHONES
2
What Is Sustainability ?
“ sustainable development meets the needs
of today without compromising the ability
of future generations to meet their own
needs”
World Commission on Environment and Development 1987
3
ASHRAE Position
“supports building sustainability as a
means to provide safe, healthy,
comfortable indoor environment while
simultaneously limiting the impact on the
Earth’s natural resources”
Why Sustainable Design?
• Buildings In The US Consume 39% Of Our Total Energy
• 70% Of Our Electricity Annually
• 5 Billion Gallons Potable Water Per Day For Toilets
• Typical Construction Generates 2.5 lbs. Of Solid Waste Per Square Foot
• High Performance Building Practices Can Reduce These Negative Environmental Impacts
Green
HVAC
Desig
n
What happens if we do ?
• Reduce Operating Costs
• Enhance Building Marketability
• Increase Worker Productivity
• Higher School Test Results
• Reduced Absenteeism
• Reduce Potential Liability
• 6 Sections of LEED
– Sustainable Sites
– Water Efficiency
– Energy & Atmosphere
– Materials & Resources
– Indoor Environmental Quality
– Innovation & Design Process
What Is LEED?
7
8
1996 2004 2010 2015 2020 2030
0%
20%
40%
60%
80%
100%
65%
25%
10% 0.5%
Consumption cap reduced
from 35% to 25% in 2010
2013 2020 2025 2030 2040
0%
20%
40%
60%
80%
100%
65%
32.5%
2.5%
2015
90% Current:
Consumption cap steadily
reduced starting in 2015
Previous:
Consumption capped at
2015 levels until 2040
Phase Out Schedule – Developed Countries
Phase Out Schedule – Developing Countries
Co
nsu
mp
tio
n
Co
nsu
mp
tio
n
Freeze
Note: acceleration shown in light blue
2015 Service Tail Review
Montreal Protocol –Changes Made on Friday September 21st, 2007
9
And Don’t Forget HCFC-22
• HCFC-22 phase-out in 2010 for new equipment
and 2020 for service tail production
– Consider alternatives for HCFCs now
• Recommended actions
– Select high efficiency units that use zero ozone
depleting refrigerants like HFC-410A, HFC-134a and
HFC-407C
10
Ohnishi Basis for ICCP/TEAP report
11
Considerations when Replacing or Retrofitting
• Difficulties in Servicing and Maintaining Existing HCFC Equipment.
• Declining Availability of HCFC Refrigerants.
• Adequate Life-Cycle Timeframes for New Equipment using HCFC’s.
• Determining the Remaining Life-Cycle of Existing Equipment.
• Understanding Alternative Equipment, Refrigerant Options and Compatibility of Both Refrigerants and Equipment.
• Containment is Key……………
Reference: HRAI Website
12
Single Chiller Design
2400 Usgpm
95F
Cooling Tower
40 kW
800 Ton Load
3 Way Valves
44F Chilled Water
Supply
85FSupply
To Chiller
800 Ton Chiller
0.55 kW/ton
Green HVAC
Design
Chiller Basics
• Air, Water Or Evaporatively Cooled
• Reciprocating, Scroll, Screw Or Centrifugal Compressors
• DX or Flooded Evaporators
Green
HVAC
Desig
n
Cooling Tower Basics
Induced Draft Tower
Forced Draft Tower
Green HVAC
Design
Load Basics
• Chilled Water Coils
Transfer Heat From
Building Air To Chilled
Water
• Process Loads
– Cooling Jackets
16
ASHRAE Standard 90.1
Green
HVAC
Desig
n
ASHRAE STD 90.1
&
STD 15
&
STD 34
Benchmark
Green
HVAC
Desig
n
AHRI Standard 550/590-98
Know your Standards!
Green
HVAC
Desig
n
The Industry AHRI Standard
Part Load Analysis (IPLV) % Load % Hrs
100 1
75 42
50 45
25 12
Systems Solution
Green
HVAC
Desig
n
Range Vs. Supply Water Temperature
CONDENSER FLUID TEMPERATURE
COOLER FLUID TEMPERATURE
SATURATED SUCTION TEMPERATURE {T }R
HEAT OFCONDENSATION
HEAT OFVAPORIZATION
97°F118.3 psig
R-134a
42°F36.6 psigR-134a
LIFT(°F)
95°F
44°F
θ2
θ2
θ1
θ1
T2
T2
T1
T154°F
85°F
• Standard ARI Conditions
– 54- 44F Chilled Water
– 85 - 95F Condenser Water
• 10F Range
• 2F Approaches In Heat
Exchangers
• 55F Lift On Compressor
Green
HVAC
Desig
n
Range Vs. Supply Water Temperature
• Change To 14F Range
– Smaller Pumps, Pipes etc.
• Maintain Supply Water
Temperature
• LMTD Increases
– Improves Chiller Performance
• Hurts Chilled Water Coil
Performance
– Deeper Coils Required
– Increased Fan Static
Pressure
Green
HVAC
Desig
n
Range Vs. Supply Water Temperature
• Maintain 14F Range
• Lower Supply Water
Temperature To 42F
• 4% Increase In Compressor
Lift
– Chiller Performance Suffers
• Chilled Water Coil
Performance Improves
Green HVAC
Design
Range Vs. Supply Water Temperature
• VAV Office Bldg In New York City
• Fixed Supply Water Temperature
• Design Conditions
• Increase Chilled Water Range From 10 To 24F
• Fan Motor Goes From 94.8 HP To 114.7 HP (21%)
• Pump Goes From 38.5 HP to 16 HP (58%)
Chiller Chilled Water Coil Fan Total
Run Capacity Perform Temp Range Pump APD Rows/fins TSP Motor size Power
Tons KW/ton (°F) HP (in. w.c.) (in. w.c.) (HP) (HP)
1 400 0.546 10 38.5 0.62 5/10 3 94.8 426.1
2 400 0.546 12 32.1 0.66 5/11 3.04 96 420.9
3 400 0.547 14 27.5 0.7 6/10 3.08 97.3 417.6
4 400 0.547 16 24 0.79 6/12 3.15 99.5 416.3
5 400 0.543 18 21.4 0.87 8/9 3.25 102.7 415.3
6 400 0.543 20 19.2 0.94 8/11 3.32 104.9 415.3
7 400 0.543 22 17.5 1.1 10/10 3.48 109.9 418.6
8 400 0.543 24 16 1.25 12/10 3.63 114.7 421.9
Green HVAC
Design
Range Vs. Supply Water Temperature
• Fixed Supply Water Temperature
• Increase Chilled Water Range From 10 to 24F
• Annual Energy Analysis
• System Peaks At 16F Range
Run C.W. Range Chiller Pumps Tower Fan S.A. Fan Total
(°F) ($/yr) ($/yr) ($/yr) ($/yr) ($/yr)
1 10 26,074 15,175 1,591 28,275 71,115
2 12 26,096 13,784 1,593 28,560 70,033
3 14 26,167 12,792 1,594 28,846 69,399
4 16 26,211 12,055 1,597 29,350 69,213
5 18 26,081 11,489 1,601 30,070 69,241
6 20 26,126 11,034 1,604 30,574 69,338
7 22 26,259 10,784 1,619 31,726 70,388
8 24 26,358 10,487 1,625 32,810 71,280
Green HVAC
Design
Range Vs. Supply Water Temperature
• Switch To Constant Volume With Reheat
• Increase Chilled Water Range From 10 to 24F
• Annual Energy Analysis
• System Peaks At 14F
– Fan Penalty Outweighs Pump Savings
Run C.W. Range Chiller Pumps Tower Fan S.A. Fan Total
(°F) ($/yr) ($/yr) ($/yr) ($/yr) ($/yr)
1 10 40,035 19,842 2,821 70,957 133,655
2 12 40,034 18,013 2,821 71,954 132,822
3 14 40,224 16,728 2,831 72,396 132,179
4 16 40,327 15,765 2,839 73,657 132,588
5 18 40,174 15,025 2,852 75,455 133,506
6 20 40,285 14,429 2,863 76,715 134,292
7 22 40,526 13,963 2,884 79,595 137,193
8 24 40,772 13,692 2,912 82,283 139,659
Green HVAC
Design
Range Vs. Supply Water Temperature
• Declining Supply Water Temperature (44 To 38F)
• Increase Chilled Water Range From 10 To 24F
• Annual Energy Analysis
• System Peaks At 16F Range And 42F SWT
• Not As Good As 16F Range And 44F SWT!
Run C.W. Range C.W. S.T. Chiller Pumps Tower Fan S.A. Fan Total
(°F) (°F) ($/yr) ($/yr) ($/yr) ($/yr) ($/yr)
1 10 44 26,074 15,175 1,591 28,275 71,115
2 12 44 26,096 13,784 1,593 28,560 70,033
3 16 44 26,211 12,055 1,597 29,350 69,213
3 14 42 27,733 12,790 1,593 28,573 70,689
4 16 42 27,779 12,039 1,593 28,570 69,981
5 18 40 29,371 11,462 1,594 28,584 71,011
6 20 40 29,351 11,002 1,596 28,872 70,081
7 22 38 30,365 10,623 1,596 28,881 71,465
Green HVAC
Design
Condenser Water Range
• Increase Condenser Water Range From 10 To 15F
• Annual Energy Analysis
• System Peaks At 10 Range
• It Costs More To Operate A System At Higher Ranges
Run Cond .W. Range Chiller Pumps Tower Fan S.A. Fan Total
(°F) ($/yr) ($/yr) ($/yr) ($/yr) ($/yr)
1 10 26,074 15,175 1,591 28,275 71,115
2 11 27,084 14,562 1,592 28,283 71,521
3 12 27,517 14,049 1,592 28,286 71,444
4 13 28,094 13,616 1,592 28,290 71,592
5 14 28,527 13,245 1,592 28,293 71,657
6 15 29,057 12,923 1,593 28,297 71,870
Green
HVAC
Desig
n
Condenser Water Relief
PerformanceImprovement
Chiller Type
Percent kW /°F condenserwater
W/C Recip. 1.1 to 1.3
W/C Scroll 1.3 to 1.5
W/C Screw 1.6 to 1.8
W/C Centrifugal 1.0 to 1.6
W/C Centrifugal VFD 2.4 to 2.6
Absorption 1.4 to 1.5
29
Why Consider Heat Recovery?
• Green Is Good
Conservation of Natural
Resources
• Lower Annual Energy
Usage
– Reduce Operating Cost
• Provide a Good Life
Cycle Analysis
30
Green
• ANSI/ASHRAE/IESNA Standard 90.1
– LEED requires you comply with 90.1 and
exceed it for more points.
– LEED requires some water conservation and
reducing evaporation from towers qualifies.
– Heat Recovery chiller in the condenser
stream reduces water evaporation.
31
Heat Recovery Requirements
• The Potential Heat Recovery At Any Point In Time Is The
Lesser Of The Heat Source Or The Heat Load
Simultaneous Heating And Cooling
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
BT
U/f
t2
Cooling Heating
Critical !!!
Must have a heat source
Cooling & heating loads are coincident
33
Single Condenser HR Design
Heat Exchanger
Pump
Heat Exchanger
Condenser Water
Pump
Chilled Water
Pump
Cooling Tower
3-Way Bypass
Valve
Boiler Loop
34
Split Condenser HR Design
Boiler Loop
Heat Recovery
Pump
3 Way Bypass
Valve
Cooling Tower
Chilled Water
Pump
Split Condenser
Heat Recovery
Chiller
Looks like a normal chiller!
They are!!!
36
Heat Pump Chiller Design
3-Way Bypass
Valve
Cooling Tower
Heat Pump
Pump
85 °F
85 °F 95 °F
Std. Chiller
140 °F 130 °F
Boiler Loop
37
Tertiary Loop Design
• Allows Different Flowrates And
Temperature Ranges In HR
Loop From Boiler Loop
• Can Reclaim Max. Energy
• Isolates Loops
• Pump Only Operates When
Required
– Std 90.1 Requires Pump
Pressure Drop Exceeds 20 ft
Tertiary Loop
10°F T.D
Main Loop
20°F T.D.
Different
Temperatures
Same Temperature
38
Heat Recovery Design
• Generally Design Boiler Load Greater Than Design
Chiller THR (Total Heat of Rejection)
– Actual Design Heat Recovery Rate Requires Annual Energy
Analysis
– Almost Never Boiler Or THR Design Capacity
– Load Will Be Met By Combination Of HR And Boiler
• THR = 1.25 x Chiller Capacity
• Only One Chiller Need Be HR Type In Multiple Chiller
Plant
– Must Be First On, Last Off
39
Heat Recovery Control
“During Heat Recovery Mode, Maintain Boiler
Return Water Temperature At 95ºF” – Boiler Supply Water Temperature Will “Float” Depending On
Actual Heating Load In Building
– 25% Boiler Load = 100°F SWT (5°F Temperature Range)
Not
“During Heat Recovery Mode, Maintain Boiler
Supply Water Temperature At 105ºF” – 25% Boiler Load = 100°F RWT
– Entering Condenser WT will be 5°F Higher Than Above
– Boiler Will Still Be Required
– Same Amount Of Energy Will Be Recovered
– Chiller will Work A Lot (10%) Harder
40
Results
0
2000000
4000000
6000000
8000000
10000000
12000000
14000000
Chillers Pumps Towers Fans Boiler HW Pumps
kW
h
Base Building Templifier HR ChillerHeat Pump
41
Geothermal Heating
65F 55F
120 - 160°F
Reheat Domestic Heat Domestic Hot H2O Process Heat
Heat Pump Benefits
– Recovers Waste Heat
– Heats Water Economically
– Saves Water
– Saves Chemical Treatment
– Reduces Blowdown & Sewer Charges
– Improves Chiller Efficiency
43
Sizing HR Chillers
• Using the THR Of Chillers Rated Cooling Capacity For HR
Design Is Not Recommended
– Undersized Chiller Will Miss HR Opportunity
– Oversized Chiller Will Waste Capital
– Possible Surge Issues
• Manual Method Described In ASHRAE Chiller Heat
Recovery Application Guide
44
Analysis is a MUST! Analysis is a MUST
BIM
45
Recommended