chiller plant applications - airah · measure & verify optimize system automate system apply...
TRANSCRIPT
Many Considerations
Water
2
Criticality Redundancy
Energy NoiseIndoor space Outdoor space
ComfortAccessibility
Climate
Marketing Codes/Standards
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Consumables + Water + Maintenance + ENERGY
Chiller Plant Operating Costs =
3
Holistic Chiller Plant Approach
Energy Cost of Plant =
Load Hours Efficiency RateStructureX X X
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Measure & Verify
Optimize System
Automate System
Apply components effectively, optimally
Select components effectively, optimally
Design system infrastructure to max efficiency potential
Operating Decisions
Design Decisions
Maintain
Automation is a key component of the optimization processbut optimization is not just smart controls
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Design Energy Vs. Annual Energy
Design Performance
Chiller58%
Tower5%
Fans24%
Pumps13%
Annual Energy Usage
Pumps22%
Tower2%
Chiller33%Fans
43%
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SustainabilitySustainability Life CycleLife Cycle
FlexibilityFlexibility
EfficiencyEfficiency
Air cooled vs Water cooledHeat rejection medium Air Water
Performance dry bulb based wet bulb based
Full Load Efficiency Lower Higher
Part load efficiency Lower# Higher
Chiller Size larger baseline
Water usage NO* YES
Location Outdoors Indoors (plant-room)
Installation Less complex More complex
Maintenance Less complex More complex
* Power generating stations use water to produce electricity# Plant efficiencies are dependent on climate, control, and other factors
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4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
10 20 30 40 50 60 70 80 90 100
COP
% Capacity
YK CSD Constant CEFT YK CSD AHRI Relief YK VSD AHRI Relief YMC2 AHRI Relief
Chillers operate for 85% of the time within this capacity range
Constant Speed, Constant CEFT
Constant Speed, AHRI Relief
Variable Speed, AHRI Relief
Variable Speed, AHRI Relief + oil-free
VSD technology unlocks efficiency benefit of natural weather conditions
Note: Above is based on water cooled centrifugal compressor technology
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The design process
•Minimize ‘transport’ energy
•Maximize the economics of high efficiency components
•Optimize ‘lift’
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Metering device
1
6 condenser
pressure
Pressure‐ enthalpy diagram
2
35 4
compressor
enthalpy
evaporator
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Pressure
Enthalpy
Lift or Differential Pressure
12.2° C6.7° C
29.4° C
Water cooled chillers Standard design lift condition
35° C
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What is Heat Recovery?ASHRAE Handbook (2008):
“In many large buildings, internal heat gains require year-round chiller operation. The chiller condenser water heat is often wasted through a cooling tower”…“[Heat recovery] uses otherwise wasted heat to provide heat at the higher temperatures required for space heating, reheat, and domestic water heating”
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Heat recovery creates and uses energy at higher chiller lift condition to improve overall building efficiency
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Boiler
Condenser
Expansion Valve
Cooling Tower
Evaporator
What is Heat Recovery?
Heat Recovery
CompressorMotor
Building with Energy Recovery
(12.2ºC) (6.7ºC)
(35ºC)(40ºC)
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Example – reheat cooled and de-humidified O/A to neutral condition for use with a passive chilled beam system with site recovered energy
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Why use a heat recovery chiller?
Social / Environmental Advantages CO2 reductions Reduced water consumption
Economic Advantages Operational savings
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Coincident heating and cooling
Cooling capacity 680 kWrHeat rejection 820 kWrPower input 140 kWe
Total COP = 1500 / 140 = 10.7
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Lower tower water temps
Higher chilled water temps
What is lift relief ?
AND / OR
Less compressor work = lower input kWeJohnson Controls - Proprietary
Reduce liftCapitalizing on ‘off‐design’ conditions ‐most of the time
Evaporator
Compressor
Condenser
Pressure
EnthalpyReduces Energy Consumption
Lift
Lowering Condenser Water Temperature
Reduces Compressor Work
Lowers the Lift
Expansion
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Reduce liftCapitalizing on ‘off‐design’ conditions ‐most of the time
Evaporator
Compressor
Condenser
Pressure
EnthalpyReduces Energy Consumption
Lift
Raising Chilled Water Temperature
Reduces Compressor Work
Lowers the LiftExpansion
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50%
0%
ENER
GY
Evaporator Temp.
Condenser Temp.
Off-
Des
ign
Lift
Load
(weight of rock)
12.8°C ECWT
44°F (6.7°C) LCHWT
29.40 C ECWT
How does lower LIFT (compression ratio) impact efficiency ?
Variable Speed Chiller Energy Usage Analogy ‐
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100%
Opportunities for Lower Lift
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Lower Condenser Water Temperature
• Lower CW Design Temperatures• Oversize Towers
• Climate wet bulb relief• Control Strategy• Chiller / Tower optimization
• Series Counter‐flow
Higher Chilled Water Temperature
• Higher CHW Design temperatures• Climate wet bulb relief• Control strategy• chilled water reset
• Series & Series Counter‐flow• Multiple CHW loops• HT loop & LT loop
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6 deg C 10 deg C 14 deg C
Series chillers
Lift is reduced 4 degrees C
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Evaporator
Condenser
Evaporator
Condenser
ECWTLCWT
ECHWT LCHWT
Evaporator 1Compressor 1
Condenser 1
Pressure
Enthalpy
Lift 1Evaporator 2
Compressor 2
Condenser 2
Lift 2
Evaporator
Compressor
Condenser
Pressure
Enthalpy
Enhanced efficiency through series counter‐flow
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160 C 110 C 60 C
290 C350 C 320 C
Today’s and tomorrow’s challenge
Additional component‐level efficiency gains will be insufficient. 1
"...we are reaching maximum technological limits at a component level and that in the future the industry will have to look at the full HVAC system for further improvements. AHRI is in the process of forming a new working group to address systems approaches for efficiency improvements and will work closely with Standard 90.1.”
- Dick Lord, co-writer of addendum ‘ch’ to ANSI/ASHRAE/IES Standard 90.1-2010, ASHRAE Press Release, December 12, 2012
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The role of controls in the optimization processBest‐in‐class algorithms that take a holistic, system‐level approach
All variable speed plant
Most Energy Efficient Chiller Plant Design
JEM is identified as the “Greenest Building” in Singapore (2013)
+++=
6.7 Plant COP
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System efficiency targets …
Singapore Green Mark v4 Platinum rating @ 0.55 kW/Ton = 6.4 plant COP
Low temp loop = 9/18 deg C with 2 x YORK YK series counter-flow CSD chiller pairs High temp loop = 15/20 deg C with 2 x YORK YK VSD chillers
Traditional chiller plant COP
JEM Project delivering 0.527 kW/TR system efficiency:
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18 C
9 C 13.5 C
AHU(s)
LT CHW loop
VPF
DOAS
VPF 20 C
15 C
Efficient System Design Concepts applied to HVAC system …
HT CHW loop
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Today’s variable speed chillers with optimized control strategies deliver outstanding real world plant-room efficiencies !
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W.A>
BMS
Johnson Controls Metasys CPO
Internet Connection
Pump VSD’s
Fan VSD’s
Hardwired devices
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Currently used HFC and Natural refrigerants
R134aR410a
R245fa R717
HydrocarbonJohnson Controls - Proprietary
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Legislation has driven refrigerant direction. Investments are long‐term and require thoughtful insight to how the equipment will be used and operated throughout its lifetime.
2017200419871970’s1930’s1830’s
Address greenhouse gas emissions
Eliminate ozone depleting CFC’s & HCFC’sMake it safe & efficientMake it work
HFOs*
Lower GWP HFCs(i.e. R‐410A, R‐134a, R32)
HFCs(i.e. R‐410A, R‐134a, R‐404A, R‐507)
HCFCs(i.e. R‐22, R‐123)
CFCs(i.e. R‐11, R‐12)
Natural Refrigerants(i.e. CO2, ammonia, water, hydrocarbons)
Available Chemicals
(Ethers, Ammonia, Water, CO2, Methylene Chloride,
etc.)
Towards the end of this decade we will start to see the introduction of new low GWP refrigerants (HFO) . HFC’s with an acceptable GWP such as R134a will continue to be available
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QUESTIONS ?
SUMMARYOptimization is a process.Innovative design is the foundation.
Chiller & Plant COP is improved when lift is reduced.
Where energy is recovered and used, Plant COP can be improved when lift is increased.
Further efficiency increases are currently being delivered at the system level.
JCI offers responsible refrigerant solutions for numerous applications.
R&D is progressing with next generation refrigerants.