chiller plant optimization - airah · pdf filedesign system infrastructure to max efficiency...

Back to BasicsChiller Plant Applications

Melbourne 28th April 2016

Johnson Controls - Proprietary

Many Considerations

Water

2

Criticality Redundancy

Energy Noise

Indoor 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 EfficiencyRate

StructureX X X


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 process

but optimization is not just smart controls


Design Energy Vs. Annual Energy

Design Performance

Chiller

58%

Tower

5%

Fans

24%Pumps

13%

Annual Energy Usage

Pumps

22%

Tower

2%

Chiller

33%Fans

43%

Johnson Controls - Proprietary & Confidential

Sustainability Life Cycle

Flexibility

Efficiency

Air cooled vs Water cooled

Heat 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


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

CO

P

% 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 ReliefVariable 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


The design process

• Minimize ‘transport’ energy

• Maximize the economics of high

efficiency components

• Optimize ‘lift’


Metering device

1

6condenser

pre

ssu

re

Pressure- enthalpy diagram

2

35 4

compressor

enthalpy

evaporator


Pressure

Enthalpy

Lift or

Differential

Pressure

12.2° C

6.7° C

29.4° C

Water cooled chillers Standard design lift condition

35° C


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”

11

Heat recovery creates and uses energy at higher chiller lift condition

to improve overall building efficiency


Boiler

Condenser

Expansion Valve

Cooling Tower

Evaporator

What is Heat Recovery?

Heat Recovery

CompressorMotor

Building with Energy Recovery

(12.2ºC) (6.7ºC)

(35ºC)(40ºC)

12

Example – reheat cooled and de-humidified

O/A to neutral condition for use with a passive

chilled beam system with site recovered energy


Why use a heat recovery chiller?

Social / Environmental Advantages

CO2 reductions

Reduced water consumption

Economic Advantages

Operational savings

13

Coincident heating and cooling

Cooling capacity 680 kWr

Heat rejection 820 kWr

Power input 140 kWe

Total COP = 1500 / 140 = 10.7


14

Lower tower water temps

Higher chilled water temps

What is lift relief ?

AND / OR

Less compressor work = lower input kWe


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


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


50%

0%

ENER

GY

Evaporator Temp.

Condenser Temp.

Off

-D

es

ign

Lif

t

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 -


100%

18


19


Legionella growth is dormant below 20C

York chillers can operate at low condenser

water temperatures

Cold tower water assists to control Legionella growth

20


Water Consumption is a

function of TOTAL HEAT

REJECTION.

HEAT REJECTION =

Cooling Capacity +

Shaft Power +

Condenser Pump Power

Thus, Lower Shaft Power =

Lower Water Consumption!

21


Benefits of Cold Cond. Water on High Temp Chiller (i.e. 14C leaving evap. YMC2)

Opportunities for Lower Lift

22

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


6 deg C 10 deg C 14 deg C

Series chillers

Lift is reduced 4 degrees C


Evaporator

Condenser

Evaporator

Condenser

ECWTLCWT

ECHWT LCHWT

Evaporator 1Compressor 1

Condenser 1

Pressure

Enthalpy

Lift 1

Evaporator 2

Compressor 2

Condenser 2

Lift 2

Evaporator

Compressor

Condenser

Pressure

Enthalpy

Enhanced efficiency through series counter-flow


140 C 100 C 60 C

290 C350 C 320 C

Enhanced efficiency through series

counter-flow


Parallel Chillers SCF Chillers

Total Capacity (kWr) 2 x 1500 2 x 1500

Evap Flow Total (L/s) 44.7 x 2 = 89.4 89.4

Evap DP (kPa) 82.4 78.9

Cond Flow Total (L/s) 69.8 x 2 = 139.6 138.7

Cond DP (kPa) 76.9 54.2

R134a Charge (kg) 2 x 603 = 1206 2 x 438 = 876

Cost ($) BASE Less than BASE

VPF Evap min (L/s) 13 22

Load (kWr) Parallel (kWe) SCF (kWe) Saving (kWe) %

3000 471.0 446.5 24.5 5.2%

2700 378.0 355.5 22.5 6.0%

2400 297.8 276.3 21.5 7.2%

2100 229.4 210.0 19.4 8.5%

1800 171.5 154.4 17.1 10.0%

1500 122.7 108.6 14.1 11.5%

1200 100.2 87.5 12.7 12.7%

900 80.9 69.5 11.4 14.1%

600 65.2 56.9 8.3 12.7%

300 75.4 66.0 9.3 12.4%

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


27

Primary / Secondary System

Know the benefits and limitations

of the system type

P/S System: Recommend to Size

Primary Pumps for more flow

than Secondary Pumps

VPF System: Pump Head of

Low Load Chiller

Primary/Secondary System

VSD & VPF System

28

Variable Chilled Water FlowVSD & VPF System


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


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:


18 C

9 C 13.5 C

AHU(s)

LT CHW loop

VPF

DOAS

VPF20 C

15 C

Efficient System Design Concepts applied to HVAC system …

HT CHW loop


Today’s variable speed chillers with optimized control strategies

deliver outstanding real world plant-room efficiencies !


W.A>

BMS

Johnson Controls Metasys CPO

Internet Connection

Pump

VSD’s

Fan

VSD’s

Hardwired devices


Currently used HFC and Natural refrigerants

R134aR410a

R245fa R717

Hydrocarbon


H20

37

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’s

Make 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


QUESTIONS ?

SUMMARY

Optimization 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.

chiller plant optimization - airah · pdf filedesign system infrastructure to max efficiency...

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