Chiller Plants for Tropical Climates - AIRAH - Home · Chiller Plants for Tropical Climates Today’s Agenda Chiller developments VSD advantages YMC2 Technology ... In recent decades,

AIRAH 2014

Chiller Plants for Tropical ClimatesToday’s Agenda Chiller developmentsVSD advantagesYMC2 Technology Chiller plant optimizationSeries counter-flow configurationOpportunities from ‘de-coupling’Opportunities from de-couplingMulti CHW loop applicationsEfficiency possibilities Example project

YMC2 – YORK® State of the Art Magnetic Centrifugal Chillers

Despite using more environmentally benign, yet less efficient refrigerants, chiller efficiency has improved significantly

In recent decades, significant gains in chiller efficiency at full & part load through advances in HX, compressor, motor, driveline, and economizers.

The biggest single efficiency gain has been at reduced ‘lift’ condition

MotorRectifier InverterDC

with the adoption of the variable speed drive.

L1

L2

L3Control electronics

C t l it d i ti

M3

U1

V1

W

L

C UV1 V3 V5

V4 V6 V2

YK YMC2Control, monitor, and communication


VSD technology benefits

Reduces inrush current to < than FL amps (soft start)

Corrects power factor close to unity

Reduces utility demand

Regulates compressor speed to provide the most efficient chiller operation, reducing energy consumption


Most recent technology introductionVariable speed magnetic bearing oil free centrifugal chillers

High efficiency permanent magnet motorg y p g

Latest Generation VSD

Frictionless magnetic bearings

Direct drive compressor

Oil free design


York magnetic bearing chillers were originally developed for mission critical nuclear submarinesdeveloped for mission critical nuclear submarines


Magnetic bearing driveline technology

Permanent Magnet Permanent Magnet MotorMotor

Impeller Impeller SectionSection

Low noise and vibrationLow inrush current – variable speedLow maintenance - no oil related componentsRapid start and re-startCompatible with the wide range of condenser water temperatures

6Johnson Controls ‐ Proprietary & Confidential

Compatible with the wide range of condenser water temperatures


Comparing fixed speed to variable speed technology

At AHRI “relief “ conditionsAt constant conditions

YK VSD

YKCSD

YMC2

VSDYK

CSDYMC2

VS YMC2

VS

Load% LWT EWT COP EWT COP COP COP % %100 6.7 29.4 6.46 29.4 6.46 6.28 6.60 2.1 5.0

VSDCSD VSDCSD YK CSD YK VSD

90 6.7 29.4 6.54 27.2 7.05 7.05 7.43 5.6 5.680 6.7 29.4 6.52 25.0 7.55 7.99 8.41 11.5 5.570 6.7 29.4 6.44 22.8 7.83 9.09 9.66 22.8 6.260 6.7 29.4 6.25 20.5 8.12 10.34 11.23 38.6 9.050 6.7 29.4 6.14 18.3 8.18 11.72 13.12 61.1 13.040 6.7 29.4 5.75 18.3 7.55 11.31 12.79 89.5 13.030 6.7 29.4 5.28 18.3 6.77 10.34 11.96 76.1 15.720 6.7 29.4 4.46 18.3 5.55 9.30 10.31 85.9 10.915 6 7 29 4 3 96 18 3 4 88 8 25 8 60 75 7 4 015 6.7 29.4 3.96 18.3 4.88 8.25 8.60 75.7 4.0


VSD chillers perform best with condenser water “relief”

13 0

14.0YK CSD Constant CEFT YK CSD AHRI Relief YK VSD AHRI Relief YMC2 AHRI Relief

Chillers operate

11.0

12.0

13.0 Chillers operate for 85% of the time within this capacity range

8.0

9.0

10.0

CO

P

5 0

6.0

7.0

4.0

5.0

10 20 30 40 50 60 70 80 90 100% Capacityp y


How to effectively apply high efficiency VSD chillers to HVAC systemsVSD chillers to HVAC systems

in tropical climates?Chiller

58%

Tower5%

Fans24%

P

Design Performance

5%Pumps13%

One of the most ‘constant’ tropical climates is SingaporeOne of the most constant tropical climates is Singapore.What levels of plant efficiency can be achieved where operating conditions have limited variance ?


Efficient chillers are a great foundation, but optimization is a process

Maintain

p p

Measure & Verify

Optimize SystemOperating Decisions

p y

Automate System

Apply components effectively, optimally

Select components effectively, optimally

Design Decisions

Select components effectively, optimally

Design system infrastructure to maximize efficiency potential


The key functional components of chiller plant optimization are the same irrespective of jobsite location

Apply variable speed drivesChillersPPumpsTower Fans

Reduce “lift”Reduce “lift”lower CW temperatureshigher CHW temperatures

Reduce pump energywide delta Tvariable flow

Efficient chiller stagingenergy based vs load based


All chillers benefit from reduced “lift”…..especially VSD chillers.How to achieve reduced ‘lift’ in tropical climates ?

Lower tower water tempsLimited opportunity at design condition.Some opportunity when at off-design.

AND

Higher chilled water temps

AND

Higher chilled water temps

Significant opportunity with HT CHW, chiller arrangement,and airside design


One has to ‘create’ the optimum operating environment

Every 1 deg C of ‘lift’ reduction improves VSD hill ffi i b 3 6%VSD chiller efficiency by 3-6% depending on the technology

MotorRectifier InverterDC

Supply

L1

L2

L3M3

U1

V1

W

L

C UV1 V3 V5

V4 V6 V2

Control electronics

Control, monitor, and communication

Every 1 deg C counts !

Johnson Controls - Proprietary & ConfidentialYMC2 – YORK® State of the Art Magnetic Centrifugal Chillers

Every 1 deg C counts !

Conventional design @ “ASIA” conditions

Pressure

Lift

32 ° C95° F 35°C

37° C

Lift

12° C12 C6° C

Enthalpy


Can we lower tower water temps ?

The cooling tower is the most effective heat transfer device in the system

Design ConditionEnergy efficiency ratio

250 ton tower super low noise tower

32 - 37 deg C

OR

= 7.5 kW / 875 kWr

= 117

30 - 35 deg CConventional design = approach 5-7 deg C

Optimized design = approach 3 4 deg C

Tower water does not have to be held constant

Optimized design = approach 3-4 deg C


Singapore Building Operation Profiles cantake some advantage of ambient wet bulb relief ASHRAE 32.8db / 27.3wb

Source: ASHRAE IWEC Weather Bin Data

Singapore tower water will achieve 3 deg C of relief based on ‘office’ hours with 5 deg C of relief available for 24/7 systemsg y


Can we raise CHW temps ?

Chiller HX approachtemperatures <= >1 deg C

Conventional coil design = 2.5 m/s Face velocity & approach 6-7 deg C

p g

Optimized coil design = < 2.0 m/s Face velocity & approach 3-4 deg C

13 deg C air off coil = 9 deg C CHW @ 4 deg C approach


12 5 / 7 0 deg C

Can we widen the CHW temperature range to 8-10 deg C?12.5 / 7.0 deg C

13.5 / 6.0 deg C

14.5 / 5.0 deg C

Design delta T 5.5C 7.5C 9.5C% Flow reduction 0 2/7.5 =27% 4/9.5 = 42%

Wide delta T chilled water systems save significant pump energy,but to use ‘similar’ CHW coils, the chillers must work harder.

Using 9 deg C CHW & 10 deg C delta T will need different AHU CHW coils


Using 9 deg C CHW & 10 deg C delta T will need different AHU CHW coils

air ON db 25air ON wb 18.5air OFF db 13Air Qty l/s 5 000

What is the impact to the AHU CHW coil with 9 deg C CHW temp and 10 deg C delta T ?Air Qty l/s 5,000 g p g

Increasing face area and reducing coil velocity is key to equivalent energy performanceIncreasing face area and reducing coil velocity is key to equivalent energy performance


1st cost economics of a 9 /19 deg C CHW system

Smaller CHW pipes

Savings Costs Larger AHU coil HX areas and p p

Smaller CHW valves and fittings

Reduced thermal insulation area

rows to achieve equivalentenergy performance

If the additional coil area cannot be d t d i AHU h i ht th Smaller CHW pumps, motor kW, and VSD’s

Smaller CHW pump electrical requirements

Smaller chiller electrical requirements

accommodated in AHU height, the AHU footprint will increase


Wide CHW delta T best suits Series Counter-flow chillers

VPF = variable primary CHW flow & fixed delta T

9 d C

VPF

CHW flow & fixed delta T

9 deg C 14.0 deg C 19 deg C

30 deg C 32.5 deg C 35 deg C

Lift is reduced 2.5 degrees C Lift is reduced 5.0 degrees C

Series Counter-Flow chillers further reduce lift


9 14 19

Series counter flow YMC2 performance at Singapore conditions (office hours)

1645 kWr1520kWr9 14 19

30 32.5 35

1645 kWr1520kWr

Load% CHW in CHWint CHWout CWin CWint CWoutUP

COPDN

COPSYS COP

100 19 13.8 9 30 32.4 35 8.75 7.83 8.29

90 19 13.8 9 29.4 31.6 33.9 9.33 8.14 8.70

80 19 13.8 9 28.8 30.7 32.8 9.96 8.49 9.20

70 19 13.8 9 28.2 29.9 31.7 10.56 8.79 9.6370 19 13.8 9 28.2 29.9 31.7 10.56 8.79 9.63

60 19 13.8 9 27.6 29.1 30.7 10.95 8.92 9.88

50 19 13.8 9 27 28.2 29.5 11.42 8.92 10.07

40 19 13.8 9 27 28 29.1 10.95 8.43 9.58

30 18.5 13.6 9 27 27.7 28.5 10.02 7.46 8.60

20 15.4 12.1 9 27 27.5 28.1 6.83 5.38 6.04


How does optimized series counter flow YMC2 efficiency compare to conventional Singapore design with YK CSD ?

Load% YK YMC2 S/C

YK CSDat AHRI

constant CWYMC2 S/C at 9 deg C & 30 deg C

with 3 deg C CW reliefLoad% YK YMC S/C

100 6.46 8.29 28%90 6.54 8.70 33%80 6.52 9.20 41%70 6.44 9.63 50%60 6.25 9.88 58%

The bulk ofoperating hours

50 6.14 10.07 65%40 5.75 9.58 66%30 5 28 8 60 48%30 5.28 8.60 48%20 4.46 6.04 35%

Chiller energy reduced on weighted average by 55% !


gy g g y

How has performance improved over conventional design ?

11 0

12.0YK CSD Constant CEFT YMC2 SCF Office

Si ifi t b fit f VSD

9 0

10.0

11.0 Significant benefit from VSD

7 0

8.0

9.0

CO

P

5.0

6.0

7.0

4.0

5.0

10 20 30 40 50 60 70 80 90 100% Capacityp y


Energy economics of a 9 /19 deg C S/C CHW system

Compared to constant speed chillers

Savings Costs Marginally higher design flow Compared to constant speed chillers

at AHRI constant condenser water

conditions

g y g gpump pressures with series HX

Note : pressures are reduced at . . part load with variable flow

CHW pump energy savings 35 % Marginally greater tower fan energy

to leverage the 3 deg C reduction in CW temperature

YMC2 S/C chillers 28-66 % more efficient Note: tower efficiency is an order of

magnitude greater than chillers

2YMC2 S/C chillers 28% more efficient at designYMC2 S/C chillers up to 66% more efficient at reduced load & lift

YMC2 S/C chillers 55% more efficient on weighted average


Typical system = CHW VAV AHU’s

HT CHW loop

9 C 14 C

19 CVPF


Are there more efficiency gains to be found ?

Can we go higher than 9 deg C CHW ?


The most efficient HVAC systems treat the latent loads separately “De-coupling”

Cooling Load Component Latent Sensible

C d ti th ll f tConduction thru walls, roof etc

Solar radiation

Lights

People

Equipment (some…most is sensible)

Infiltration

Ventilation

System heat gains


A typical application that de-couples loads is a chilled beam system

DOAS

+Chilled Beam

+One HVAC system performs

all dehumidification One HVAC system performs

only sensible cooling De-coupled

Typically @ 14 degrees C CHW

De coupled

Typically @ 6 degrees C CHW

The management of high humidity infiltration loads in tropical climatesmakes the application of chilled beam systems challenging.

The question becomes…. can we utilize 14 degree HT chilled water in some way ?


Let’s examine a CHW system for a chilled beam application

ACB HT CHW loopDOAS supplies dry cool conditioned primary O/A to the active chilled beams

LT CHW loop 14 0 C

6 C 11 C

LT CHW loop(S/C chillers)

14.0 C

VPF VPF16 C 18 C

Pl t Pl tPlant room Plant room


Efficiency is further improved where a % of O/A load is removed by the HT loop

ACB HT CHW loop DOAS with cascade reduction in primary air temp

LT CHW loop14 0 C

6 C 11 C

C oop(S/C chillers)14.0 C

VPFVPF16 C

Pl t

18 C

Pl t Plant roomPlant room


In tropical climates treating the outside air load separately through a DOAS has merit, particularly for applicationsthrough a DOAS has merit, particularly for applications that require higher percentages of fresh air.

DOAS can provide-DOAS can provide

Effective de-humidification

Th bili ffi i l d h d i f id The ability to efficiently cascade the reduction of outside air temperature

The ability to include energy recovery devices


With VAV t d i t t l i t iti l

DOAS applied to a traditional VAV system

VAV AHU(s)DOAS diti th O/A

With a VAV system space dew point control is not as critical.

DOAS pre-conditions the O/Asupplied to the zone VAV AHU’s

9 C 14 C

CHW loop14 C

19 C

VPF

VPF19 C


What efficiency levels can the HT loop chiller deliver ?

Load% YK YMC2 s/c YMC2

Office profile

YK CSDat AHRI

constant CW

YMC2 S/C at 9 deg C YMC2 at 14 deg C Office profile

Load% YK YMC s/c YMC100 6.46 8.29 28% 9.2090 6.54 8.70 33% 9.77

42%49%

80 6.52 9.20 41% 10.3770 6.44 9.63 50% 10.9560 6.25 9.88 58% 11.38

59%70%82%

50 6.14 10.07 65% 11.6840 5.75 9.58 66% 11.2030 5 28 8 60 48% 10 34

90%95%95%30 5.28 8.60 48% 10.34

20 4.46 6.04 35% 8.45

HT YMC2 delivers weighted average 79% improvement over base design

95%89%


With dual loops, plant performance can be further improved

11 0

12.0YK CSD Constant CEFT YMC2 Evap 14/18C YMC2 SCF Office

9.0

10.0

11.0

6 0

7.0

8.0

CO

P

4.0

5.0

6.0

10 20 30 40 50 60 70 80 90 10010 20 30 40 50 60 70 80 90 100% Capacity

The greater the load transferred to the HT loop, the greater the efficiency is further improved


Example of Dual CHW loop project

JEM ProjectSingapore

Multi stageMulti stage fresh air

treatment

Dual CHWDual CHW loops

Elevated CHW tempsC te ps

Series counter-flow LT chillers

Wide delta T LT loop


Low temp loop = 9/18 deg C with 2 S/C York YK CSD chiller pairs

Hi h t l 15/20 d C ith 2 Y k YK VSD hillHigh temp loop = 15/20 deg C with 2 x York YK VSD chillers

Greenmark ‘Platinum’ rating @ 0.55 kW/Ton = 6.4 plant COP


For Consideration

High Efficiency VSD or VSD magnetic bearing chillers High Efficiency VSD or VSD magnetic bearing chillers

Raise CHW supply temperatures

Wide delta T CHW with series counter-flow chiller arrangement Wide delta T CHW with series counter-flow chiller arrangement

Re-evaluate design approach temperatures

cooling towers are efficient and low costcooling towers are efficient and low cost

lower face velocity coils

De-couple and condition outside air loads separately De-couple and condition outside air loads separately

Dual HT & LT CHW loops with cascade coils & ‘low lift’ VSD chillers


If these concepts can be successfully li d th b i f Si thapplied on the basis of Singapore weather

data, there is even greater opportunity in less stringent tropical locations.

VSD centrifugal and VSD magnetic bearing centrifugal chillersVSD centrifugal and VSD magnetic bearing centrifugal chillerscan offer significant efficiency opportunities in tropical climates

A wide delta T, variable CHW flow, Series Counter-Flow chiller , ,configuration maximizes these benefits

Revised design temperatures further maximizes these benefits


SmartSmart GreenGreenSmart Smart GreenGreenIntegrated Sustainable Solutions

The innovation requirements of green buildings challenge traditional paradigms


Documents

Chiller Plants for Tropical Climates - AIRAH - Home · Chiller Plants for Tropical Climates Today’s Agenda Chiller developments VSD advantages YMC2 Technology ... In recent decades,