Ice Storage: Design and Application

engineers newsletter live Course Outline

Ice Storage: Design and Application The grid of the future will incorporate a higher percentage of renewable energy (like wind and PV solar). Unfortunately these energies have no natural storage mechanism. Thermal storage is the easiest way to restore this critical component of fossil fuel-based energy. We’ll cover a bit of theory and application, then design a small ice storage system from layout to operation and control. We’ll discuss how to make it affordable on small chilled-water systems, expose hidden costs in energy tariffs, and identify and address the most common stumbling blocks. By attending this event you will learn: 1. A clear understanding of ice storage 2. An economic rationale for ice storage 3. How to dispel common myths about ice storage 4. How to avoid the most common stumbling blocks Program Outline: 1) Overview – Why ice now? 2) Typical applications

a) Ice storage overview b) Design overview

3) Qualifying a job a) Ice storage design process b) Qualifying preliminary analysis c) Qualifying design utility rates and ROI

4) Design process a) Proper use of glycol b) Architecture

5) Controls a) System operating modes b) Energy savings goal c) Diagnostics

6) Economics first cost 7) Economics analysis - TRACE

© Trane, a business of Ingersoll Rand 1

engineers newsletter live Presenter Biographies

Ice Storage: Design and Application

Susanna Hanson | applications engineer | Trane

Susanna is an applications engineer at Trane with over eleven years of experience with chilled-water systems and HVAC building load and energy analysis. Her primary responsibility is to aid system design engineers and Trane personnel in the proper design and application of HVAC systems. Her main areas of expertise include chilled-water systems and ASHRAE Standard 90.1. She is also a Certified Energy Manager. She has authored several articles on chilled water plant design, and is a member of ASHRAE SSPC 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings. Susanna earned a bachelor’s degree in industrial and systems engineering from the University of Florida, where she focused on building energy management and simulation.

Lee Cline | senior principle systems engineer | Trane

Lee is an engineer in the Systems Engineering Department with over 28 years experience at Trane. His career at Trane started as a factory service engineer for heavy refrigeration, helping to introduce the CVHE centrifugal chiller with electronic controls to the industry. Following that Lee was a member of the team that kicked off the microelectronic building automation and Integrated Comfort Systems controls – ICS - offering at Trane. He continues to push new unit and system control and optimization concepts into the industry. As a Systems Engineer Lee also has the opportunity to discuss HVAC system application and control with owners, engineers and contractors on a daily basis. Lee has a Bachelors degree in Mechanical Engineering from Michigan Technological University. He is a Registered Professional Engineer in the State of Wisconsin.

Paul Valenta |Sales Manager | CALMAC Mfg. Corp.

Paul is a Manager at CALMAC Manufacturing Corporation with over 20 years experience in the ice energy field. CALMAC celebrated its 60th birthday in 2008 and has a long history of providing valuable energy saving products. Paul’s career at CALMAC started as a regional sales manager responsible for sales and distribution of ice storage systems in the Midwest. Without utility incentives and off peak rates, Paul specialized in developing partial ice energy storage applications in schools and offices and demonstrating their viability with life cycle costs. He has been involved in several hundred ice storage projects all over the world. Currently Paul is Marketing and Sales Manager for CALMAC. He has authored several articles on ice energy storage and rightsizing cooling plants with energy storage, is a member or ASHRAE and is a LEED Accredited Professional. Paul has a degree in Electrical Engineering from the University of Nebraska.


Ice Storage Design and Application

EngineersNewsletter Live

© 2009 Trane2

©200

8 Trane Inc.

“Trane” is a Registered Provider with The American Instituteof Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members available on request.

This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, ordealing in any material or product.Questions related to specific materials,methods, and services will be addressedat the conclusion of this presentation.


© 2009 Trane3

Copyrighted Materials

This presentation is protected by U.S. and international copyright laws. Reproduction, distribution, display, and use of the presentation without written permission of Trane is prohibited.

© 2009 Trane, Inc. All rights reserved.

© 2009 Trane4


Today’s Topics

Overview—why ice now?

Typical applications

Qualifying a job

Design process

Minimizing first cost, maximizing ROI

Project level considerations

Controls

Economics


© 2009 Trane5

Today’s Presenters

Lee Cline

SystemsEngineer

Paul Valenta

Calmac NationalSales Manager

Susanna Hanson

Applications Engineer


Why Ice Storageand Why Now?


© 2009 Trane7

Why Thermal Energy Storage?

1. “Green” power needs it

2. It reduces CO2 emissions

3. It saves money and has a good ROI

© 2009 Trane8

1400

1200

1000

800

600

400

200

0

Rea

l Po

wer

Ou

tpu

t, k

W

Seconds Since 00:00:00 June 2005

One Turbine, Ten Days at 1 Second Resolution

0 200,000 400,000 600,000 800,000

Rea

l Po

wer

Ou

tpu

t, k

W

One day at Ten Second Resolution

0 1000 2000 3000 4000 5000 6000 7000

4000

3000

2000

1000

0

Source:Carnegie Mellon Electricity Institute


© 2009 Trane9

Source: Carnegie Mellon Research Institute

© 2009 Trane10

Source: Carnegie Mellon Research Institute


© 2009 Trane11





Simulation of Source Energy Utilization and Emissions for HVAC Systems

A report ASHRAE TC 6.9 in response to the 991-TRP work statement

© 2009 Trane12

ASHRAE TC 6.9 Research Project

Monthly Power Plant Fuel Source

Coal Dominate Generation(MG&E Profile)

Balanced Generation(WEPCO Profile)

800

700

600

500

400

300

200

100

0

800

700

600

500

400

300

200

100

0

1 12 1 12month month

ho

ur

ho

ur


© 2009 Trane13

ASHRAE TC 6.9 Research Project

Ice Storage Site, Source, & CO2 Savings

88%

88%

86%

100%

CO2

Emission(% of base)

87%

88%

86%

100%

SourceEnergy

(% of base)

86%86%86%86%OfficeIce Storage

88%88%87%88%SchoolW/C—Ice

87%87%86%87%SchoolA/C—Ice

100%100%100%100%Electric Chiller(base)

SourceEnergy

(% of base)

SiteElectricity(% of base)

CO2

Emission(% of base)

SiteElectricity(% of base)

Coal/Natural Gas Utility Generation Profile

Coal Dominant Utility Generation Profile

System

© 2009 Trane14

“Thermal energy storage systems should be promoted as an environmentally beneficial technology. These systems have been historically touted as beneficial in terms of operation cost. This study suggests that the economic benefits can be accompanied by environmental ones…”

“…Source energy reductions were generally on the order of 10%. Global warming impact reductions were also on the order of 10%...”

Simulation of Source Energy Utilization and Emissions for HVAC Systems

Conclusions


© 2009 Trane15





© 2009 Trane16

Why Concentrate on Ice?

Thermal Storage Incremental Cost

Thermal Storage – Installed Ton Hours

Co

st P

er T

on

Ho

ur

1. Rapid discharge2. Emergency use

Chilled Water

Modular Ice



Ice StorageOverview

Paul Valenta

© 2009 Trane18

Energy Storage Background

Ice harvesters

Ice on pipe—external melt

Encapsulated ice storage

Modular ice on pipe —internal melt


© 2009 Trane19

Six Modes of Energy Storage Systems

1. Charging

2. Charging and cooling a night time load

3. Chiller cooling

4. Energy storage cooling

5. Chiller and energy storage cooling

6. Off

© 2009 Trane20

Ice on Pipe—Internal Melt

Strengths Six modes of operation

Efficient, modular, reliable

Cataloged data

Fast installation

Weaknesses Secondary heat transfer fluid

Not easily direct buried


© 2009 Trane21

Ice on Coil—Internal Melt

Easily adapts to chilled-water system

Added:

• Blending valve

• Diverting valve

• Ice tank(s)

• Controls

• Heat transfer fluid

Temperature

Control Valve

© 2009 Trane22

Ice Building and Melting Cycle Ice on Pipe—Internal Melt


© 2009 Trane23

Rules of Thumb for Partial Ice Storage Designs

Most projects are partial storage unless utilities support full storage with rebates

Chiller loses 1/3 of capacity during ice build

Ice making time is usually 8 to 10 hours

Typical systems store about 1/4 to 1/3 of the total design day ton-hours

Chiller reduction• To 50% in schools, 35%–40% office buildings

Design for high delta T, 15°F to 18°F


Design OverviewSusanna Hanson


© 2009 Trane25

Visualize the Potential Impact

Building kW load duration curve

Diversity factor• Average load/peak load

• Total kW

• HVAC kW

• Chiller tons

k-12 school

average

peak200

100

0

total kW

cooling kW

© 2009 Trane26

University of Arizona

21 chillers33,000 tons

156 ice tanks23,400 ton-hours

Ice storagesaves $423,000/year

Self-generates at 4–5 cents/kWh

Purchases at 7.5-8.5 cents/kWh

Ice flattens load profile for utility rate negotiation


© 2009 Trane27

Design Day Load Profile

0

100

200

300

400

500

600

700

800

900

12 2 4 6 8 10 12 2 4 6 8 10 12

Time

To

ns

© 2009 Trane28

How Much Chiller Capacity?

0

100

200

300

400

500

600

700

800

900

12 2 4 6 8 10 12 2 4 6 8 10 12

Idle Chiller Capacity

Design Day Cooling Load profile

Conventional System(3)—240 ton chillers

Time

To

ns


© 2009 Trane29

Comparable Ice Storage Design

0

100

200

300

400

500

600

700

800

900

12 2 4 6 8 10 12 2 4 6 8 10 12

Storage System Excess Capacity

Design Day Load

Storage System(2)—240 ton chillers2,130 ton-hrs. storage

Time

To

ns

© 2009 Trane30

Comparable Ice Storage Design

0

100

200

300

400

500

600

700

800

900

12 2 4 6 8 10 12 2 4 6 8 10 12

Conventional System (3) 240 ton chillers

Storage System Excess Capacity

Design Day Load

Time

To

ns

Storage System(2)—240 ton chillers2,130 ton-hrs. storage


© 2009 Trane31

Time

To

ns

Conventional2 (3)—240 ton chillers

Design Day With Chiller Outage

0

100

200

300

400

500

600

700

800

12 2 4 6 8 10 12 2 4 6 8 10 12

Storage Chiller

Stored Cooling

Storage System Shortfall

© 2009 Trane32

Time

To

ns

Storage System1 (2) 240 ton chillers2,130 ton-hr storage

Design Day With Chiller Outage

0

100

200

300

400

500

600

700

800

12 2 4 6 8 10 12 2 4 6 8 10 12

Storage Chiller

Stored Cooling

Storage System Shortfall


© 2009 Trane33

Design OverviewFull Storage

Short on-peak windows or

Good rebates available

downsized chiller

makeice

meltice

chiller

chiller capacity

midnight 6 a.m.

makeice

makeice

meltice

chiller

chiller capacity

downsized chillermidnight

Partial Storage

Reduces peak demand

Shifts load to more efficient time

© 2009 Trane34

Air-cooled or Water-cooled?

Not that much design difference

Air-cooled • Reduces initial investment for efficient system

• Fewer components to select

Water-cooled• Large chiller capacities (>500 tons)

• May require multiple stages of compression

• Expanded economizer cycle


© 2009 Trane35

Expand “Free” Cooling Cycle

Ice extends the hours for water economizer free cooling cycle

Reduces tower energy by charging tanks at night with fans unloaded

© 2009 Trane36

Condenser Relief

Ice Making

Dry Bulb

Wet Bulb Ice Making

WB design

DB design

RELIEF

65

70

75

80

85

90

95

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Typical August Day in Memphis

Tem

per

atu

re


© 2009 Trane37

EERLeaving Solution Temp and Ambient Relief

7

8

9

10

11

12

13

14

15

20 25 30 35 40 45 50 55

Leaving Solution Temp (F)

EE

R 95 Air

85 Air

75 Air

© 2009 Trane38

Fossil Ridge High School

260,000 ft2 conditioned space

Grades 10–12

1,800 students

• Rule of thumb

• 400 sq. ft./ton

Peak load—250 Tons

• 1,040 sq. ft./ton

Actual chiller—130 tons, 1,280 ton hrs ice storage

• 2,000 sq. ft./ton


© 2009 Trane39

Retrofits

Chillers/systems being replaced anyway• Ice chillers of equal capacity cost the same

• Cost less if downsize the chillers

Energy prices are high

Energy shortages are common

Rebates or incentives are available• States (California, New York)

• Utilities (Duke Power, FPL)

© 2009 Trane40

Simple Air-Cooled Chilled Water System

Chiller

Downstream ice tanks

Blending valve

Diverting valve

Controls

Heat transfer fluid


© 2009 Trane41

Ice Tanks in SeriesDownstream of Screw/Scroll Chiller

ICEBANK

air handlers

V1V2

P1

P2

back pressure regulating valve

© 2009 Trane42

Ice Tanks in Series Upstream of Centrifugal Chiller

air handlers

V2

P1

P2

V1A

B

C

A

B C

regulating valve


© 2009 Trane43

Ice and Chillers in Series

Chiller in upstream position:• Increases chiller efficiency (screws more than CTVs)• Increases chiller capacity (screws more than CTVs)• Decreases ice capacity• Simplifies system layout• Tank capacity loss doesn’t exceed chiller efficiency and

capacity benefits• Smaller system, screw or scroll—tanks downstream

Chiller in downstream position:• Decreases chiller efficiency• Decreases chiller capacity• Increases ice capacity (reduced number of tanks?)• Tank capacity benefit is substantial• Larger system, centrifugals—tanks upstream

S.I.C.


QualifyingLee Cline


© 2009 Trane45

Qualify Job

Ice Storage Design Process

• New/existing• Preliminary

load profile• Peak• Daily curve

•Utility rate•Future use

AcquireData

TargetProspective

Job

• Chilled water • Doing

something• Utility cost

conscious• Day loading• Tank siting• Code

compliance

• Ice Pick

InitialSystemSizing

InitialFinancialAnalysis

• SystemAnalyzer

• First Pass

InitialFinancialProposal

•Proforma•ROI•Schedule

© 2009 Trane46

Ice Energy Storage Design

Project Specifics

Chilled water

Building usage and future plans• Emergency cooling

• Enhanced redundancy

• Expansion

• Green energy

• Teaching tool


© 2009 Trane47


Project Specifics

Chilled water

Building usage and future plans

Space for tank farm• Outside

• Inside

• Stacked

• Partial or complete burial

© 2009 Trane48


Project Specifics

Chilled water

Building usage and future plans

Space for tank farm

System distribution design• Glycol throughout system

• Wide delta T/low flow / low temp

• Constant/variable flow

• Dedicated ice/cooling chillers


© 2009 Trane49

Qualify Job





AcquireData

TargetProspective

Job




compliance

• Ice Pick

InitialSystemSizing


• SystemAnalyzer

• First Pass



© 2009 Trane50


Acquire Data

Cooling load • Design day hourly profile Tall peak?

Low and flat?

Off peak usage?

Acquire from…• Load program

• Chiller logs

• BAS logs

July

75°

Partn/Floors

Rooms

Roofs

Walls

Int. Loads

AirflowsInt. Loads



Qualifying Preliminary Analysis

Paul Valenta

© 2009 Trane52


Cooling Load

24 hour design day load profile from• Load program

• Chiller logs

• BAS logs

Night loads• > 20% of peak loads

• If > 20% consider night chiller

July

75°

Partn/Floors

Rooms

Roofs

Walls

Int. Loads

AirflowsInt. Loads


© 2009 Trane53

Internal-Melt Tank Dynamics

Performance dependencies• Flow rate

• Temperatures

• Ice capacity remaining

Performance requirements• Peak discharge rate

• Hourly discharge rate

• Total storage capacity

© 2009 Trane54

Equipment Selection Criteria

Heat transfer fluid type and concentration

Ice tank model

Chiller daytime contribution as a % of nominal

Chiller charging capacity as a % of nominal

Supply and Return delta T

24 hour load profile• Full or partial storage


© 2009 Trane55

IcePick—Input Screens

© 2009 Trane56

Design Day Load Profile


© 2009 Trane57

Equipment Selection Example

© 2009 Trane58



© 2009 Trane59


© 2009 Trane60

Design Day Analysis


© 2009 Trane61

Ice Storage Selection Options

46 ton nominal chiller/3 ice tanks

58 ton nominal chiller/2 ice tanksLess charging time

Demand limit chiller on peak day

or

70 ton nominal chiller/3 ice tanksHigher first cost

Will it pay back?

or


Qualifying DesignUtility Rates

Lee Cline


© 2009 Trane63

Qualify Job





AcquireData

TargetProspective

Job




compliance

• Ice Pick

InitialSystemSizing


• SystemAnalyzer

• First Pass



© 2009 Trane64


Acquire Data

Cooling load

Utility rates• kW charge—Ratcheted?

• On-Peak/Off-Peak—kW and/or KWh

• Real time pricing

• Up front or on-going incentives


© 2009 Trane65


Monthly Load Factor

Month's kWh Usage _

Peak Demand (kW) x 730 hours per month

© 2009 Trane66


Monthly Load Factor

Load Factor = 63 Load Factor = 37

010

20

3040

5060

70

80

Lo

ad (

To

ns)

1 3 5 7 9 11 13 15 17 19 21 23

Hour

High Load Factor

010

20

30

40

5060

7080

Lo

ad (

To

ns)

1 3 5 7 9 11 13 15 17 19 21 23

Hour

Low Load Factor



Qualifying RatesPaul Valenta

© 2009 Trane68

Electric Rates and Types

Demand rate—most common• Ratchet

• Time of day


© 2009 Trane69

$ 11.00/kW and $.08/kWh*

Ton-hr Cost on a Standard Demand Rate

Nighttime Costs Daytime Costs

Demand Cost $/kWhEnergy Cost $/kWh Ton-hr cost $/Tn. Hr.

$.016

$.08

$.108

$.1884

$.08$.08

$.06

$.00

* Assumes building with daytime peak

© 2009 Trane70



• Time of day

Stepped rate


© 2009 Trane71

Georgia Power Electric Rates PLM-4 All consumption (kWh) not greater than

200 hours times the billing demand:First 3,000 kWh .................................................................@...................... 9.317¢ per kWhNext 7,000 kWh .................................................................@.......................8.540¢ per kWhNext 190,000 kWh .............................................................@.......................7.350¢ per kWhOver 200,000 kWh..............................................................@.......................5.696¢ per kWh

All consumption (kWh) in excess of 200hours and not greater than 400 hourstimes the billing demand.................................................. @.......................... 0.949¢ per kWh

All consumption (kWh) in excess of 400hours and not greater than 600 hourstimes the billing demand.................................................. @.......................... 0.715¢ per kWh

All consumption (kWh) in excess of 600hours times the billing demand....................................... @........................... 0.623¢ per kWhMinimum Monthly Bill:

A. $15.00 base charge plus $6.83 per kW of billing demand with a ratchet of 95% of peak

B. Summer demand

© 2009 Trane72



• Time of day

Stepped rate

Flat rate

Real-time pricing



Qualifying ROILee Cline

© 2009 Trane74

Qualify Job





AcquireData

TargetProspective

Job




compliance

• Ice Pick

InitialSystemSizing


• SystemAnalyzer

• First Pass




© 2009 Trane75

Qualify Job





AcquireData

TargetProspective

Job




compliance

• Ice Pick

InitialSystemSizing


• SystemAnalyzer

• First Pass



© 2009 Trane76


DetailedJob

Data

RefineStorageSizing

• Design temps

• RefinedChiller Selection

• Refined Storage Selection• Ice Pick

Detailed Design

RefinedFinancialAnalysis

• Operating modes

• Productionsystem

• Distributionsystem

• Control• Seq• Mode chart• Pts List

DesignWater

System

• TRACE 700• Financial goals

• Detailed loadprofile• Peak• Daily curve

• Utility rate• Future use• Tank location

Commissioning

SystemValidation

• Piping• Controls



DesignSusanna Hanson

© 2009 Trane78

Proper Use of Glycol

EG v PG• EG more efficient

• PG less toxic

Affect on coils• New

• Existing

Affect on chillers• Reduced heat transfer

• Reduced flow rates, wider delta T


© 2009 Trane79

freeze specificsolution point heat viscosity

water 32°F 1.0 Btu/lb-°F 1.5 cp

ethylene 11.4°F 0.90 Btu/lb-°F 3.2 cpglycol (25%)

propylene 9.3°F 0.92 Btu/lb-°F 5.2 cpglycol (30%)

fluid temperature = 40°F


© 2009 Trane80


Do you want glycol through the whole building?• Smaller systems—yes Freeze protection in coils (no need for coil pumping)

Not a lot of glycol, avoid HX cost

• Larger systems—maybe not First cost of glycol

Pumping cost

Glycol compatible control valves

Heat exchangers are a one time cost

Head pressure requirements for larger systems


© 2009 Trane81

Proper Use of Glycol—Coils

7.8386.40.6239564525% EG

6.8975.50.64455645water

pressuredrop (fluid)ft. H2O

fluidflow rategpm

pressuredrop (air)in. H2O

totalcapacityMBh

coilrows

enteringfluid°F solution

© 2009 Trane82


9.8186.40.8345584525% EG

7.8386.40.6239564525% EG

6.8975.50.64455645water


fluidflow rategpm


totalcapacityMBh

coilrows



© 2009 Trane83


14.3120.70.6545564525% EG

9.8186.40.8345584525% EG

7.8386.40.6239564525% EG

6.8975.50.64455645water


fluidflow rategpm


totalcapacityMBh

coilrows


© 2009 Trane84


7.5284.10.6445564025% EG

14.3120.70.6545564525% EG

9.8186.40.8345584525% EG

7.8386.40.6239564525% EG

6.8975.50.64455645water


fluidflow rategpm


totalcapacityMBh

coilrows


We didn’t change the coil, so this works in existing building retrofits too


© 2009 Trane85


6.4176.80.6445563825% EG

7.5284.10.6445564025% EG

14.3120.70.6545564525% EG

9.8186.40.8345584525% EG

7.8386.40.6239564525% EG

6.8975.50.64455645water


fluidflow rategpm


totalcapacityMBh

coilrows


© 2009 Trane86

chillerpumps

existingchillers

coolingcoil

ice storagetanks

icepump

loadpump

VFD

icevalve

ice-makingchiller

heatexchanger

Dedicated Ice Chillers with HX

Ice chiller on tank loop shields building from glycol

Tanks shielded from building pressure

Ice chiller can be used as a backup


© 2009 Trane87

Chiller Impact of Glycol

Chiller plus ice cooling mode• 48–56 for upstream chiller

• 60-ton nominal chiller

• 25% glycol

• Ice making capable

Ice charging mode• 21.6 average leaving chiller (from IcePick)

• 134 gpm (from IcePick)

• 60-ton nominal chiller

• 25% glycol

© 2009 Trane88

Chiller Selections—Dual Modes


© 2009 Trane89

Chiller Selections—Dual Modes

© 2009 Trane90

Proper Use of Glycol—Chillers

Tank surface area affects tank charging temperature• Ice tank types and tank manufacturers vary May need another tank if the charging temp is too low

• Make sure chiller can handle the charging temperature Chiller types and chiller manufacturers vary

Chillers are selected for lower leaving water temperatures—why not take advantage of it? Wider system T—lower flows

Lower supply water temperatures



ArchitectureSusanna Hanson

© 2009 Trane92

Design—Project Level Considerations

How should it be piped• Constant volume—3-way valves on AHU coils

• Constant primary/variable secondary

• Variable primary flow

Direction of flow during charge and discharge• Same direction for best operation


© 2009 Trane93

Chilled Water Distribution DesignConstant Volume

3-way valves on coils

Wider delta Ts reduce pumping horsepower • Larger CV system justified

Better for small systems

© 2009 Trane94

Chilled Water Distribution DesignConstant Volume

air handlers

back pressureregulating valve

ICEBANK

V1

P1


© 2009 Trane95

Chilled Water Distribution DesignVariable Primary Flow

Preference for high system delta T in systems with ice

• Gives the chiller more flow turndown

• New chiller designs don’t need this for good turndown

If glycol throughout system

• Variable flow and pump pressure optimization save more energy than primary secondary

• Wide delta T may have eliminated pump penalty already

Not as much experience

• IcePick does not currently model it

Controls more complicated

• Cool plus charge mode more difficult

© 2009 Trane96

Chilled Water Distribution DesignVariable Primary Flow

air handlers


ICEBANK

V1

P1

variable speed pump


© 2009 Trane97

ICEBANK

air handlers


V1V2

P1

P2

Chilled Water Distribution DesignConstant Primary/Variable Secondary

variable speed pump

© 2009 Trane98


Ice chillers and cooling only chillers • Simplified pumping and control

Natural way to blend water temps to control the distribution supply water temp• Needed for simultaneous Freeze + Cool mode

If glycol throughout system • Variable flow and pump pressure optimization

• Increased net-usable ton hours from higher return water temperatures


© 2009 Trane99

Alternative Designs

How many pumps? Pump location?

Bypass location?

Valves location?

© 2009 Trane100

ICEBANK

air handlers


V1V2

P1

P2


variable speed pump


© 2009 Trane101

air handlers

regulating valve

V2

P1

P2

V1A

B

C

A

B C

Alternative Designs

© 2009 Trane102

Series, Decoupled, Chiller Downstream

P1

V1

HX

water

glycol

simple bypass

V2

V2

P1

V1

HX

water

glycol

recirculation to temper hx supply

P2 P3P2


6. Controls

Controls


© 2009 Trane104

Thermal Storage

Control of an ICE System

Define and document the modes

Define the goal

Coordinate with the utility rate structure

Operator interface


© 2009 Trane105

1. Cool building with chiller only2. Cool building with ice only3. Cool building with chiller & ice4. Make ice5. Make ice & cool building6. Off

Thermal Storage Control

System Operating Modes

© 2009 Trane106

System Mode Diagrams

Ice Making Mode

ice valve

31°F

blendvalve

131 gpm

20°F

20°F CHW SP

100%


© 2009 Trane107

Ice StorageFreeze Mode Termination

11 22 33 44 55 66 77 88

charge time, hourscharge time, hours

flu

id t

emp

erat

ure

lea

vin

g s

tora

ge

tan

k

99 1010

26°F(-3.3°C)

28°F(-2.2°C)

30°F(-1.1°C)

32°F(0°C)

0

terminatefreeze mode

© 2009 Trane108

Control Mode Definition

Making Ice

--

BlendValve

Off

DistributionPump

15°F

(100% thru ice)

Enable

CHWSP: 20°F

Terminate @ CHWR 27°F

On

at design

Make Ice

IceValve

ChillerChillerPump

Mode

31°F

131 gpm

20°F

ice valve blendvalve

20°F CHW SPTerminate @CHWR 27°F

100%


© 2009 Trane109


Making Ice and Cool

42°F

BlendValve

Modulate on

remote ∆P

DistributionPump

15°F

(100% thru ice)

Enable

CHWSP: 20°F

Terminate @ CHWR 27°F

On

at design

Make Ice

IceValve

ChillerChillerPump

Mode

12°F

131 gpm

20°F

42°F

20°F CHW SP

blendvalveice valve

100%

42°F

© 2009 Trane110


Chiller + Ice Cooling

50% RLA42°F CHW SP

131 gpm

46°F56°F

32°F


42°F

100%


© 2009 Trane111

Ice Energy Storage

Energy Saving Goal

Peak shaving—kW reduction

Load shifting—kWh deferral

Real-Time pricing response

© 2009 Trane112

makeice

midnight 6 a.m. noon 6 p.m. midnight00

25

50

75

cool

ing

load

, % o

f des

ign

100

controlledmeltice

chiller

kW avoidance Do not run out of ice!

cool

ing

load

, % o

f des

ign

makeice


25

50

75

100

meltice

chiller

Energy Saving Goal

Peak Shaving—kW Reduction


© 2009 Trane113

Energy Saving Goal

Load Shifting—kWh Deferral

kWh deferralMelt as much ice as possible!

makeice

midnight 6 a.m. 6 p.m. midnight

completemeltice

noon

chiller

© 2009 Trane114

Modulate on remote ∆P

40°F

(100% to load)

42°FEnable

RLA Limit: 50%

CHWSP: 42°F

On

at design


40°F

(100% to load)

BlendValve

Modulate on

remote ∆P

DistributionPump

42°FEnable

RLA Limit: 30%

CHWSP: 42°F

On

at design


IceValve

ChillerChillerPump

Mode

makeice


25

50

75

cool

ing

load

, % o

f des

ign 100

controlledmeltice

chiller

makeice


completemeltice

noon

chiller


Peak Shaving vs. Load Shifting


© 2009 Trane115

-

42°F

80°F0% to load)

40°F(100% to load)

40°F(100% to load)

40°F(100% to load)

BlendValve


42°FOFFOnIce Only


55°F(0% Ice)

Enable

CHWSP 42°F

OnChiller Only

DistributionPump

IceValve

ChillerChillerPump

Mode

Off-OffOffOff


15°F(100% to ice)

EnableCHWSP 23°F

OnMake Ice & Cool

Off15°F(100% to ice)

EnableCHWSP 23°F

OnMake Ice


42°FEnableCHWSP 42°F

RLA Limit 30-50%

OnChiller & Ice

Ice Storage


© 2009 Trane116


Diagnostics

131 gpm

23°F56°F

32°F


32°F


© 2009 Trane117

Time of day based mode selection

Direct measurement of building demand

Demand response signal from utility

Monitoring of real-time pricing

Control of an Ice System

Utility Rate Coordination

© 2009 Trane118

makeice


kWh deferralMelt as much ice as possible!

responsivemeltice

noon

chiller

Energy Saving Goal

Real Time Pricing Response


© 2009 Trane119

Operator interface

• Well-documented sequence of operation

• Mode diagram based graphical interface

Flexible chiller demand control

• Three button manual control

Control of an Ice System

Informed Operators

© 2009 Trane120

0

10

20

30

40

50

60

70

80

90

100

To

ns

Noon

PARTIAL STORAGE—CHILLER PRIORITY(HOT-HUMID DAY)

ICE

DISCHARGING

ICE

MAKING

CHILLER

0

10

20

30

40

50

60

70

80

90

100

To

ns

Noon

PARTIAL STORAGE—ICE PRIORITY(WARM DAY)

ICE

DISCHARGING

CHILLER

ICE

MAKING

0

10

20

30

40

50

60

70

80

90

100

To

ns

Noon

FULL STORAGE(COOL DAY)

ICE

DISCHARGING

ICE

MAK-

ING

Control of an Ice SystemKeep It Simple

WarmWarmDayDay

Hot &Hot &HumidHumid

DayDay

CoolCoolDayDay


© 2009 Trane121

Thermal Storage

Control of an ICE System

Define the modes• Support all six

Define the goal• Peak shaving—kW reduction• Load shifting—kWh deferral• Real-time pricing response

Coordinate with the utility rate structure• Direct measurement of building demand• Time of day based mode selection• Demand response signal from utility• Monitoring of real-time pricing

Operator interface


Economics First Cost

Paul Valenta


© 2009 Trane123

Making the Economics Work

Use actual utility rate for life cycle costs if possible

Use storage for the safety factor

Use actual load profile for equipment selection

Take credit for smaller electrical and mechanical ancillary equipment

Take advantage of any utility rebates that might be available

Use low flow high delta T energy distribution

Use low temperature air distribution

© 2009 Trane124

10% less energy/sq ft. than average Florida state building

Energy Charges:

$ 0.0700/kWh On-Peak

$ 0.0477/kWh Off Peak

Demand Charge:

$ 8.33/kW/month

Fort Myers Regional Service Center


© 2009 Trane125

Fort Myers Regional Service Center

Conventional A/C System Energy Storage

Chillers $717,000 $447,000

Ice Storage $0 $357,000

Pipe & Pumps $ 395,000 $264,000

Air Distribution $ 988,000 $976,000

TOTAL COST $ 2,100,000 $2,044,000

FPL Rebate $0 $187,500

NET Cost to Customer $ 2,100,000 $1,856,500Net Cost/Ton $2,800 $2,475

Net First Cost Savings $ 243,500

Annual Savings over past 3 years

Electricity (Demand & Energy) $119,500

Maintenance & Water (no cooling towers) $25,000

Total Annual Operating Savings $144,500


Economic AnalysisTRACE

Susanna Hanson


© 2009 Trane127

Economic Assumptions

Electricity: $0.09198 per kWh, first 15,000$0.04347 thereafter

Demand: $0.00 first 50 kW$12.91 thereafter

Base: (2) 50-ton air-cooled chillers, no ice

Alt 1: 60-ton air-cooled chiller, 320 ton-hours of ice

Alt 2: 70-ton air-cooled chiller, 464 ton-hours of ice

© 2009 Trane128

Load Profile

Peak design: 77 tons

4°F unoccupied setback

Minimal unoccupied load

Optimum start

Base case: (2) 50-ton chillers


© 2009 Trane129

ICEBANK

air handlers

V1V2

P1

P2

Thermal Storage Possibilities

320 ton/hrs2 tanks

60-ton air-cooled chiller back pressureregulating valve

•1

© 2009 Trane130

ICEBANK

V1V2

P1

P2

Thermal Storage Possibilities

464 ton-hrs3 tanks

70-ton air-cooled chiller

40

56

air handlers


•1


© 2009 Trane131

Economics

Alt 1: (2) 50-ton chillers

Alt 2: (1) 60-ton chiller(2) tanks (320 t-h)

Alt 1: $51,600/yr

Alt 2: $48,300/yr

Alt 1: $143,000 first cost

Alt 2: $158,000 first cost

3.7 year payback

IRR 30%

© 2009 Trane132


© 2009 Trane133

Reduced Demand

© 2009 Trane134

Larger Storage System


© 2009 Trane135

Lower kW

About the same kWh

11 year payback versus no storage, 10.5% IRR

Smaller storage system better

Larger Storage System

© 2009 Trane136


© 2009 Trane137

What If We Got a Rebate?

© 2009 Trane138

Could We Have Done Moreto Maximize ROI?

Other benefits

Focus on incremental cost to the project

Negotiate with utility for different tariff



Conclusion

© 2009 Trane140

Ice Storage Design and Application Summary

Reduces a building’s utility bill and benefits the environment as well

Will play a significant role in the utility grid of the future

Applicable over a wide range of building sizes and types

Simple and economical

You don’t need a time-of-day rate, an expensive kilowatt-hour charge, or even a demand ratchet to get an attractive return on investment


© 2009 Trane141

References for This Broadcast

Where to Learn More

Subscribe at Subscribe at www.trane.com/engineersnewsletterwww.trane.com/engineersnewsletter

© 2009 Trane142

Watch Past Broadcasts

ENL Archives

www.trane.com/bookstore

Insightful topics on HVAC system design:• Chilled-water plants• Air distribution• Refrigerant-to-air systems• Control strategies• Industry standards and LEED• Energy and the environment• Acoustics• Ventilation• Dehumidification


© 2009 Trane143

2009 ENL Broadcasts

November 4 Air-Handling Systems, Energy, and IAQ


engineers newsletter live Bibliography

Ice Storage: Design and Application

Trane Publications Eppelheimer, D., “An Engineering Strategy for Ice Storage,” Engineers

Newsletter 16-6 (1987).

Solberg, P., “Ice-Storage as Part of a LEED Building Design,” Engineers Newsletter 36-3 (2007).

Trane Engineers Newsletters Live Broadcasts available to purchase from <www.trane.com/bookstore>

“Small Chilled-Water Systems: Design and Application (part I),” Engineers Newsletter Live broadcast, APP-CMC019-EN (DVD), 2004

“Small Chilled-Water Systems (part II),” Engineers Newsletter Live broadcast, APP-CMC033-EN (DVD), 2008

Industry Trade Journal Articles Tarcola, A., “Fire and Ice. University of Arizona increases turbine efficiency

with ice storage,” Distributed Energy, March/April 2009

MacCracken, M.,“Thermal Energy Storage In Sustainable Buildings,” ASHRAE Journal:Building For The Future Supplement, September 2004.

MacCracken, M., “Thermal Energy Storage Myths,” ASHRAE Journal, September 2003.

Analysis Software Trane Air-Conditioning and Economics (TRACE™ 700). Available at

<www.trane.com/Commercial/DNA/View.aspx?i=1136>

TRACE™ 700 User’s Manual, CDS-PRM001-EN, 2009.

Industry Websites

“Fossil Ridge Case Study,” Available at <www.calmac.com>

References

The Spectrum of Power from Utility-Scale Wind Farms and Solar Photovoltaic Arrays Carnegie Mellon Electricity Industry Center Working Paper CEIC-08-04

Simulation of Source Energy Utilization and Emissions for HVAC Systems A report ASHRAE TC 6.9 in response to the 991-TRP work statement


http://www.trane.com/bookstore

http://www.trane.com/Commercial/DNA/View.aspx?i=1136

Documents

Ice Storage: Design and Application