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“Condenser Water Heat

Recovery"

Julian de Bullet

ASHRAE Distinguished Lecturer

V.P. Business Development

FAFCO Thermal Storage Systems

PLEASE MUTE CELL PHONES

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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

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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

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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?

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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

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Freeze

Note: acceleration shown in light blue

2015 Service Tail Review

Montreal Protocol –Changes Made on Friday September 21st, 2007

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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

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Ohnishi Basis for ICCP/TEAP report

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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

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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

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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

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ASHRAE Standard 90.1

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ASHRAE STD 90.1

&

STD 15

&

STD 34

Benchmark

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AHRI Standard 550/590-98

Know your Standards!

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The Industry AHRI Standard

Part Load Analysis (IPLV) % Load % Hrs

100 1

75 42

50 45

25 12

Systems Solution

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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

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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

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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

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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

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Why Consider Heat Recovery?

• Green Is Good

Conservation of Natural

Resources

• Lower Annual Energy

Usage

– Reduce Operating Cost

• Provide a Good Life

Cycle Analysis

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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.

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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

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Single Condenser HR Design

Heat Exchanger

Pump

Heat Exchanger

Condenser Water

Pump

Chilled Water

Pump

Cooling Tower

3-Way Bypass

Valve

Boiler Loop

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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!!!

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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

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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

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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

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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

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Results

0

2000000

4000000

6000000

8000000

10000000

12000000

14000000

Chillers Pumps Towers Fans Boiler HW Pumps

kW

h

Base Building Templifier HR ChillerHeat Pump

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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

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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

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Analysis is a MUST! Analysis is a MUST

BIM

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