trane engineers newsletter live · ©2012 trane engineers newsletter live: ... dedicated...
TRANSCRIPT
Trane Engineers Newsletter Live
Air-to-Air Energy RecoveryPresenters: Ronnie Moffitt, Dennis Stanke, John Murphy, Jeanne Harshaw (host)
Handout_cover.ai 1 8/23/2012 11:11:49 AM
Agenda
Air-to-Air Energy RecoveryPresenters: Ronnie Moffitt, Dennis Stanke, John Murphy, Jeanne Harshaw (host)
With the increased focus on reducing energy use in buildings, more projects are considering the use of air-to-air energy recovery.
And energy codes are evolving to require energy recovery in more applications. This ENL will discuss the various technologies
used for air‐to‐air energy recovery and the importance of properly controlling these devices in various systems types.
Viewer learning objectives
1. Summarize how to design and control exhaust-air energy recovery to maximize the energy-saving benefits
2. Understand the the various air-to-air energy recovery technologies
3. Understand the advantages and drawbacks of various air-to-air energy recovery technologies
3. Summarize how recent changes to energy codes impact the requirement for using exhaust‐air energy recovery in buildings
Agenda
Welcome, introduction
Why recover energy?
a) Reduce energy use (psychrometrics of EA energy recovery)
b) Comply with energy codes (ASHRAE Standard 90.1, IECC)
c) Review the definition of effectiveness
Discuss common technologies (advantages & drawbacks, typical performance)
a) Coil loop
b) Heat pipe
c) Fixed-plate heat exchanger
d) Fixed-membrane heat exchanger
e) Total-energy wheel
f) Comparison of technologies
Proper control and integration into HVAC systems
a) Show colorful psych chart with hourly weather data
b) Mild weather (turn device off when hOA < hEA or DBTOA < DBTEA)
c) Cold weather (modulate capacity to prevent over-heating)
d) Frost prevention during cold weather
e) Review operating modes for a mixed-air VAV system
Suggestions for cost-effective application of energy recovery
a) ASHRAE 90.1-2010 requires exhaust-air energy recovery in more applications
b) Total-energy recovery devices transfer both sensible heat and water vapor (larger reductions in plant capacity, less susceptible to frosting)
c) Centralize exhaust to better balance airflows and maximize recovery (DEER unit configuration, Std 62.1 and restroom exhaust)
d) Minimize cross-leakage with proper fan placement
e) Importance of proper control (include bypass dampers to enable economizing in mixed-air systems,
modulate capacity to prevent over-heating, analyze frost prevention methods)
f) Specify AHRI-certified components (introduce AHRI 1060 certification program)
Summary
Agenda_October.ai 1 8/22/2012 4:44:04 PM
©2012 Trane Engineers Newsletter LIVE: Air-to-Air Energy Recovery
Presenter biographies
Ronnie Moffitt | applications engineering | TraneRonnie joined Trane in 1996 and currently is an airside applications engineer whose responsibility is to aid design engineers and Trane sales personnel in the proper design and application of HVAC systems. His primary focus has been dehumidification and air-to-air energy recovery. This includes the development, design and control optimization of desiccants in commercial HVAC systems. He has several patents related to these subjects, and serves on related ASHRAE engineering committees. He is current chairman of the AHRI Air-to-Air Energy Recovery Ventilation Equipment section.
Ronnie led the development of the Trane CDQ system, a winner of the R&D 100 Award for The Most Technologically Significant New Products of 2005. He is a certified Energy Manager (CEM) by Association of Energy Engineers and received his B.S. in Aerospace Engineering from Syracuse University.
John Murphy | applications engineer | TraneJohn has been with Trane since 1993. His primary responsibility as an applications engineer is to aid design engineers and Trane sales personnel in the proper design and application of HVAC systems. As a LEED Accredited Professional, he has helped our customers and local offices on a wide range of LEED projects. His main areas of expertise include energy efficiency, dehumidification, dedicated outdoor-air systems, air-to-air energy recovery, psychrometry, and ventilation.
John is the author of numerous Trane application manuals and Engineers Newsletters, and is a frequent presenter on Trane’s Engineers Newsletter Live series. He also is a member of ASHRAE, has authored several articles for the ASHRAE Journal, and has been a member of ASHRAE’s “Moisture Management in Buildings” and “Mechanical Dehumidifiers” technical committees. He was a contributing author of the Advanced Energy Design Guide for K-12 Schools and the Advanced Energy Design Guide for Small Hospitals and Health Care Facilities, a technical reviewer for the ASHRAE Guide for Buildings in Hot and Humid Climates, and a presenter on ASHRAE’s “Dedicated Outdoor Air Systems” webcast.
Dennis Stanke | staff applications engineer | TraneWith a BSME from the University of Wisconsin, Dennis joined Trane in 1973, as a controls development engineer. He is now a Staff Applications Engineer specializing in airside systems including controls, ventilation, indoor air quality, and dehumidification. He has written numerous applications manuals and newsletters, has published many technical articles and columns, and has appeared in many Trane Engineers Newsletter Live broadcasts.
An ASHRAE Fellow, he currently serves as Chairman for ASHRAE Standard 189.1, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings. He recently served as Chairman for ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality, and he served on the USGBC LEED Technical Advisory Group for Indoor Environmental Quality (the LEED EQ TAG).
PresenterBiographies_October.ai 1 8/23/2012 9:24:35 AM
©2012 Trane Engineers Newsletter LIVE: Air-to-Air Energy Recovery
Air-to-Air Energy Recovery
Ingersoll Rand
© 2012 Trane, a business of Ingersoll-Rand2
Air-to-Air Energy Recovery (Course ID: 0090008664)
1.5Approved for 1.5 GBCI hours for LEED professionals
“Trane” is a Registered Provider with The American Institute of Architects Continuing Education System. Credit earned on completion of this program will be
C S f C freported to CES Records for AIA members. Certificates of Completion are 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
f t ti th d f h dli
© 2012 Trane, a business of Ingersoll-Rand3
of construction or any method or manner of handling, using, distributing, or dealing in any material or product.
Visit the Registered Continuing Ed i P (RCEP) W b i Education Programs (RCEP) Website for individual state continuing education requirements for Professional Engineers.
RCEP t
© 2012 Trane, a business of Ingersoll-Rand4
www.RCEP.net
Copyrighted Materials
This presentation is protected by U.S. and international p p ycopyright laws. Reproduction, distribution, display, and use of the presentation without written permission of Trane is prohibited.
© 2012 Trane, a business of Ingersoll-Rand. All rights reserved.
© 2012 Trane, a business of Ingersoll-Rand5
© 2012 Trane, a business of Ingersoll Rand. All rights reserved.
learning objectives
After today’s program you will be able to:
Design and control exhaust-air energy recovery to maximize th i b fitthe energy-saving benefits
Identify the advantages and drawbacks of various air-to-air energy recovery technologies
Comply with recent changes to energy codes regarding the requirements for exhaust-air energy recovery
© 2012 Trane, a business of Ingersoll-Rand6
Today’s Presenters
© 2012 Trane, a business of Ingersoll-Rand7
Dennis StankeApplications
Engineer
Ronnie MoffittApplications
Engineer
John MurphyApplications
Engineer
Agenda Why implement exhaust-air energy recovery?
Common air-to-air energy recovery technologiesgy y g
Proper control and integration into HVAC systems
Suggestions for cost-effective application of energy recovery
© 2012 Trane, a business of Ingersoll-Rand8
Agenda Why implement exhaust-air energy recovery?
• Reduce overall system energy use
• Comply with energy codes
Common air-to-air energy recovery technologies
Proper control and integration into HVAC systems
Suggestions for cost-effective application
© 2012 Trane, a business of Ingersoll-Rand9
Exhaust-Air Energy Recovery
air-to-airheat exchanger
EA'EA' EAEA
© 2012 Trane, a business of Ingersoll-Rand10
OA OA'
180
160
140
120
hu
mid
ity80
sensible-energy recovery(Atlanta, Georgia)
CACA
120
100
80
60
40
y ratio, g
rains/lb
of d
ry a
70
50
40
60
EAEA
OA'OA'coolingOA
coolingOA
© 2012 Trane, a business of Ingersoll-Rand11
20
air
11030 40 50 60 70 80 10090
dry-bulb temperature, °F
4030
20
heatingOA
heatingOA OA'OA'
180
160
140
120
hu
mid
ity
80
total-energy recovery(Atlanta, Georgia)
CACA
120
100
80
60
40
y ratio, g
rains/lb
of d
ry a
70
50
40
60
coolingOA
coolingOA
EAEA
OA'OA'
sensible
© 2012 Trane, a business of Ingersoll-Rand12
20
air
11030 40 50 60 70 80 10090
dry-bulb temperature, °F
4030
20
180
160
140
120
hu
mid
ity80
total-energy recovery(Atlanta, Georgia)
CACA
120
100
80
60
40
y ratio, g
rains/lb
of d
ry a
70
50
40
60
coolingOA
coolingOA
EAEA
OA'OA'
sensible
© 2012 Trane, a business of Ingersoll-Rand13
20
air
11030 40 50 60 70 80 10090
dry-bulb temperature, °F
4030
20
OA'OA'sensible
heatingOA
heatingOA
Why Use Exhaust-Air Energy Recovery?
Operating Cost Installed Cost
f Reduces cooling and heating energy use• Heating energy savings
is generally greater than cooling energy savings
Increases fan energy use
Allows downsizing of cooling and heating plants• Total-energy recovery
typically allows for largest cooling plant reductions
Added pressure loss may
© 2012 Trane, a business of Ingersoll-Rand14
Increases fan energy use Added pressure loss may increase fan motor sizes
May require additional exhaust ductwork
Agenda Why implement exhaust-air energy recovery?
• Reduce overall system energy use
• Comply with energy codes
Common air-to-air energy recovery technologies
Proper control and integration into HVAC systems
Suggestions for cost-effective application
© 2012 Trane, a business of Ingersoll-Rand15
Why Recover Energy in Buildings? Save energy and operating costs
C l ith Comply with:• Energy codes (IECC), following either ASHRAE Standard 90.1
or ICC requirements
• Green-building codes (IgCC-based), following either Standard 189.1 or ICC requirements
© 2012 Trane, a business of Ingersoll-Rand16
• Energy label (ENERGY STAR) or building rating systems (LEED®)
IECC—International Energy Conservation Code
ICC International Code Council (ICC) requirements ICC—International Code Council (ICC) requirements
IgCC—International green Construction Code
© 2012 Trane, a business of Ingersoll-Rand17
Primary ASHRAE St d d
Model Energy C d
how standards fit with
Energy Codes
Local Energy Code
Standards
Std 90.1Std 90.1
Code
90.1 Path90.1 Path
ICC PathICC Path
IECCIECCOther Sources
© 2012 Trane, a business of Ingersoll-Rand18
ICC PathICC PathExpertiseExpertise
ANSI StdsANSI StdsNFPANFPA
An ANSI standard in mandatory-language co sponsored by ASHRAE
What is Standard 90.1?
language, co-sponsored by ASHRAE, USGBC, and IES, that:• Provides minimum design energy
requirements for commercial and high-rise residential buildings
© 2012 Trane, a business of Ingersoll-Rand19
• It does not apply to low-rise residential
• It covers building envelope, HVAC, water heating, power and lighting
Individual fan systems that have both a design supply air capacity of 5000 cfm or greater and have a minimum outdoor air supply of 70%
Standard 90.1-2007, Section 6.5.6.1Exhaust-Air Energy Recovery
5000 cfm or greater and have a minimum outdoor air supply of 70% or greater of the design supply air quantity shall have an energy recovery system with at least 50% recovery effectiveness. Fifty percent energy recovery effectiveness shall mean a change in the enthalpy of the outdoor air supply equal to 50% of the difference between the outdoor air and return air at design conditions. Provision h ll b d t b t l th h t t t it
© 2012 Trane, a business of Ingersoll-Rand20
shall be made to bypass or control the heat recovery system to permit air economizer operation as required by Section 6.5.1.1.
Must recover energy in any system with both: D i l i fl f 5 000 f
Standard 90.1-2007, Section 6.5.6.1Exhaust-Air Energy Recovery
• Design supply airflow of 5,000 cfm or more
• Minimum outdoor airflow 70% or more of design supply airflow
Must meet “energy recovery effectiveness” ≥ 50% (vent load-reduction ratio = (ho – hco)/(ho – hr) ≥ 0.50)
© 2012 Trane, a business of Ingersoll-Rand21
( ( o co) ( o r) )
Bypass or control requirements to avoid heat recovery during air economizer operation
defined by ASHRAE Standard 90.1“Energy Recovery Effectiveness” (ERE)
hr
hcoho
ERE =(ho – hco)(ho – hr)
he
exhaust
outdoor
return
conditionedoutdoor
© 2012 Trane, a business of Ingersoll-Rand22
hcoho
ERE = ventilation load-reduction ratio≥ 0.50
Each fan system shall have an energy recovery system when the system’s supply air flow rate exceeds the value listed in Table 6.5.6.1
Standard 90.1-2010, Section 6.5.6.1Exhaust-Air Energy Recovery
system s supply air flow rate exceeds the value listed in Table 6.5.6.1 based on the climate zone and percentage of outdoor air flow rate at design conditions. Energy recovery systems required by this section shall have at least 50% energy recovery effectiveness. Fifty percent energy recovery effectiveness shall mean a change in the enthalpy of the outdoor air supply equal to 50% of the difference between the
td i d t i th l i t d i diti P i i
© 2012 Trane, a business of Ingersoll-Rand23
outdoor air and return air enthalpies at design conditions. Provision shall be made to bypass or control the energy recovery system to permit air economizer operation as required by 6.5.1.1.
Must recover energy in any system with good potential which depends upon supply airflow
Standard 90.1-2010, Section 6.5.6.1Exhaust-Air Energy Recovery
potential, which depends upon supply airflow, minimum outdoor airflow (≥30%) and climate, as shown in Table 6.5.6.1
Must meet “energy recovery effectiveness” ≥ 50% (vent load-reduction ratio = (ho – hco)/(ho – hr) ≥ 0.50)
© 2012 Trane, a business of Ingersoll-Rand24
Bypass or control requirements to avoid heat recovery during air economizer operation
Standard 90.1-2010, Section 6.5.6.1Exhaust-Air Energy Recovery
TABLE 6.5.6.1 Energy Recovery Requirement (I-P)% Outdoor Air at Full Design Flow
≥10% ≥20% ≥30% ≥40% ≥50% ≥60% ≥70%
Climate Zone
≥10%
and
<20%
≥20%
and
<30%
≥30%
and
<40%
≥40%
and
<50%
≥50%
and
<60%
≥60%
and
<70%
≥70%
and
<80%
≥80%
Design Supply Fan Flow, cfm
3B, 3C, 4B, 4C, 5B NR NR NR NR NR NR
1B, 2B, 5C NR NR NR NR ≥26000 ≥12000 ≥4000
6B NR NR ≥11000 ≥5500 ≥4500 ≥3500 ≥2500 ≥1500
Std 90.1-2007≥5000 ≥5000
≥5000
© 2012 Trane, a business of Ingersoll-Rand25
6B NR NR ≥11000 ≥5500 ≥4500 ≥3500 ≥2500 ≥1500
1A, 2A, 3A, 4A, 5A, 6A NR NR ≥5500 ≥4500 ≥3500 ≥2000 ≥1000 ≥0
7, 8 NR NR ≥2500 ≥1000 ≥0 ≥0 ≥0 ≥0
Std 90.1-2010 – More Stringent
Standard 90.1-2013, expected Section 6.5.6.1Exhaust-Air Energy Recovery
TABLE 6.5.6.1 Energy Recovery Requirement (I-P)% Outdoor Air at Full Design Flow
≥10% ≥20% ≥30% ≥40% ≥50% ≥60% ≥70%
Climate Zone
≥10%
and
<20%
≥20%
and
<30%
≥30%
and
<40%
≥40%
and
<50%
≥50%
and
<60%
≥60%
and
<70%
≥70%
and
<80%
≥80%
Design Supply Fan Flow, cfm
3B, 3C, 4B, 4C, 5B NR NR NR NR NR NR NR NR
1B, 2B, 5C NR NR NR NR ≥26,000 ≥12,000 ≥5000 ≥4000
6B ≥28000 ≥26500 ≥11 000 ≥5500 ≥4500 ≥3500 ≥2500 ≥1500
Std 90.1-2013
© 2012 Trane, a business of Ingersoll-Rand26
6B ≥28000 ≥26500 ≥11,000 ≥5500 ≥4500 ≥3500 ≥2500 ≥1500
1A, 2A, 3A, 4A, 5A, 6A ≥26000 ≥16000 ≥5500 ≥4500 ≥3500 ≥2000 ≥1000 ≥0
7, 8 ≥4500 ≥4000 ≥2500 ≥1000 ≥0 ≥0 ≥0 ≥0
Std 90.1-2013 Std 90.1-2010 and Std 90.1-2013
Standard 90.1-2010, Section 6.5.6.1Exhaust-Air Energy Recovery Exceptions
a. Laboratory systems meeting 6.5.7.2.b S t i th t t l d d th t h t db. Systems serving spaces that are not cooled and that are heated
to less than 60°F.c. Systems exhausting toxic, flammable, paint, or corrosive fumes
or dust.d. Commercial kitchen hoods used for collecting and removing
grease vapors and smoke.
© 2012 Trane, a business of Ingersoll-Rand27
g pe. Where more than 60% of the outdoor air heating energy is
provided from site-recovered or site-solar energy.f. Heating energy recovery in climate zones 1 and 2.
Standard 90.1-2010, Section 6.5.6.1 (cont.)Exhaust-Air Energy Recovery Exceptions
g. Cooling energy recovery in climate zones 3C, 4C, 5B, 5C, 6B, g g gy y , , , , ,7, and 8.
h. Where the largest source of air exhausted at a single location at the building exterior is less than 75% of the design outdoor air flow rate.
i. Systems requiring dehumidification that employ energy recovery in series with the cooling coil
© 2012 Trane, a business of Ingersoll-Rand28
recovery in series with the cooling coil.j. Systems expected to operate less than 20 hrs per week at the
outdoor air percentage covered by Table 6.5.6.1
Some exceptions to exhaust-air ER requirements:L b t t ti 6 5 7 2 ( t i VAV
Standard 90.1-2010, Section 6.5.6.1Exhaust-Air Energy Recovery
a. Laboratory systems meeting 6.5.7.2 (e.g., certain VAV lab exhaust and supply systems)
e. Systems where site-recovered or site-solar heat provides >60% of the energy needed to heat outdoor air
g. Cooling energy recovery in cool, dry climates (zone 3C,
© 2012 Trane, a business of Ingersoll-Rand29
4C, 5B, 5C, 6B, 7, and 8)
i. Dehumidification systems using energy recovery in series with the cooling coil
Zone 7Zone 6
Zone 5
Dry (B) Moist (A)Marine (C)
© 2012 Trane, a business of Ingersoll-Rand30
Based on Std 169 draft
Model Green Building Code
how standards fit with
Green Building Codes
Primary ASHRAESecondary
ASHRAE Standard g(by ICC)
IgCCIgCC
Primary ASHRAE Standards
Std 90.1Std 90.1
ASHRAE Standard
Std 189.1Std 189.1 189.1 Path189.1 PathLocal High
Performance Green
Building Code ICC PathICC Path
Other Sources
ExpertiseExpertise
© 2012 Trane, a business of Ingersoll-Rand31
ExpertiseExpertise
ANSI StdsANSI StdsCodesCodes
An ANSI standard in mandatory-language, co-sponsored by ASHRAE, USGBC, and IES, that:
What is Standard 189.1?
sponsored by ASHRAE, USGBC, and IES, that:
• Provides minimum design requirements for high-performance green buildings (HPGB)
• Applies to the same buildings as Std 90.1 and Std 62.1
• It covers building site, water use, energy
© 2012 Trane, a business of Ingersoll-Rand32
It covers building site, water use, energy use, indoor environmental quality, environmental impact
Standard 189.1, Section 7.4.3.6Exhaust-Air Energy Recovery
7.4.3.6 Exhaust-Air Energy Recovery. The exhaust-air energy recovery requirements defined in Section 6.5.6.1 of ANSI/ASHRAE/IES Standard 90.1 shall be used except that the energy recovery effectiveness shall be 60% and the requirements of Table 7.4.3.6 shall be used instead of those of Table 6.5.6.1 of
© 2012 Trane, a business of Ingersoll-Rand33
ANSI/ASHRAE/IES Standard 90.1.
Must use recovery energy based on energy recovery potential which depends on climate outdoor airflow
Standard 189.1-2011, Section 7.4.3.6Exhaust-Air Energy Recovery
potential, which depends on climate, outdoor airflow (≥10%) and supply airflow per Table 7.4.3.6
Must meet “energy recovery effectiveness” ≥ 60% (vent load-reduction ratio = (ho – hco)/(ho – hr) ≥ 0.60)
Must include bypass or control requirements to avoid
© 2012 Trane, a business of Ingersoll-Rand34
yp qheat recovery during air economizer operation
Standard 189.1-2011 vs. Standard 90.1-2010 Exhaust-Air Energy Recovery
TABLE 7.4.3.6 Energy Recovery Requirement (I-P)% Outdoor Air at Full Design Flow
≥10% ≥20% ≥30% ≥40% ≥50% ≥60% ≥70%
Climate Zone
≥10%
and
<20%
≥20%
and
<30%
≥30%
and
<40%
≥40%
and
<50%
≥50%
and
<60%
≥60%
and
<70%
≥70%
and
<80%
≥80%
Design Supply Fan Flow, cfm
3B, 3C, 4B, 4C, 5B NR NR NR NR NR NR ≥5000 ≥5000
1B, 2B, 5C NR NR NR NR ≥26,000 ≥12,000 ≥5000 ≥4000
6B NR ≥22500 ≥11 000 ≥5500 ≥4500 ≥3500 ≥2500 ≥1500
© 2012 Trane, a business of Ingersoll-Rand35
6B NR ≥22500 ≥11,000 ≥5500 ≥4500 ≥3500 ≥2500 ≥1500
1A, 2A, 3A, 4A, 5A, 6A ≥30000 ≥13000 ≥5500 ≥4500 ≥3500 ≥2000 ≥1000 ≥0
7, 8 ≥4000 ≥4000 ≥2500 ≥1000 ≥0 ≥0 ≥0 ≥0
Std 189.1-2011 Std 90.1-2010 and Std 189.1-2011
ASHRAE Standard 84
Defines method of testing air to air heat exchangersair-to-air heat exchangers
AHRI Standard 1060
Defines conditions and procedures for rating and
© 2012 Trane, a business of Ingersoll-Rand36
procedures for rating and certifying performance
defined by ASHRAE Standard 84 and AHRI Standard 1060
Effectiveness
sensible effectivenessṁ
X4 X3
X
total effectiveness
S = (T1 – T2)(T1 – T3)ṁmin
ṁOA
= (h1 – h2)ṁOA ṁOA
ṁEA
© 2012 Trane, a business of Ingersoll-Rand37
X2X1T =
(h1 – h3)ṁmin
ṁmin = smaller of ṁOA or ṁEA
Equal Airflows
10,000 cfm 78°F DB67 gr/lb29 2 Btu/lb
EAEA
10,000 cfm
(38.4 – 33.6)52%
10,000 cfm
92°F DBT103 gr/lb38.4 Btu/lb
29.2 Btu/lb
84.5°F DBT85 gr/lb33.6 Btu/lb
OA
© 2012 Trane, a business of Ingersoll-Rand38
QT = 4.5 10,000 cfm (38.4 – 33.6 Btu/lb) = 216 MBh
T = (38.4 33.6)(38.4 – 29.2)10,000 cfm
= 52%10,000 cfm
Unequal Airflows
7,500 cfmEAEA
78°F DB67 gr/lb29 2 Btu/lb
10,000 cfm
85°F DBT86 gr/lb34.0 Btu/lb
(38.4 – 34.0)64%
10,000 cfmcompared to 52%
with equal airflows
OA92°F DBT103 gr/lb38.4 Btu/lb
29.2 Btu/lb
© 2012 Trane, a business of Ingersoll-Rand39
QT = 4.5 10,000 cfm (38.4 – 34.0 Btu/lb) = 200 MBh
T = (38.4 34.0)(38.4 – 29.2)7,500 cfm
= 64%10,000 cfm q
compared to 216 MBhwith equal airflows
sponge in large bucket of water More water absorbed
Less effective (does not absorb all water in bucket)
sponge in small puddle of water
© 2012 Trane, a business of Ingersoll-Rand40
Less water absorbed
More effective(absorbs all water in puddle)
ASHRAE 90.1-2010, Section 6.5.6.1
Exhaust-Air Energy Recovery“Fifty percent energy recovery effectiveness shall mean a change in the enthalpy of the outdoor air supply equal to 50% of the difference between the outdoor air and return air enthalpies at design conditions.”
29.2 Btu/lbEAEA
© 2012 Trane, a business of Ingersoll-Rand41
h2 ≤ 33.8 Btu/lb38.4 Btu/lbOA
Equal Airflows
10,000 cfmEAEA Does meet
ASHRAE 90.1(h ≤ 33 8 Bt /lb)
78°F DB67 gr/lb29 2 Btu/lb
10,000 cfm
(38 4 33 6)10 000 cfm
OA
(h2 ≤ 33.8 Btu/lb)
92°F DBT103 gr/lb38.4 Btu/lb
29.2 Btu/lb
84.5°F DBT85 gr/lb33.6 Btu/lb
© 2012 Trane, a business of Ingersoll-Rand42
T = (38.4 – 33.6)(38.4 – 29.2)10,000 cfm
= 52%10,000 cfm
52% ventilation load reduction
Unequal Airflows
7,500 cfmEAEA Does not meet
ASHRAE 90.1(h ≤ 33 8 Bt /lb)
78°F DB67 gr/lb29 2 Btu/lb
10,000 cfm
(38 4 34 0)10 000 cfm
OA
(h2 ≤ 33.8 Btu/lb)
92°F DBT103 gr/lb38.4 Btu/lb
29.2 Btu/lb
85°F DBT86 gr/lb34.0 Btu/lb
© 2012 Trane, a business of Ingersoll-Rand43
T = (38.4 – 34.0)(38.4 – 29.2)7,500 cfm
= 64%10,000 cfm
48% ventilation load reduction
“As-Applied” vs. “Rated” Effectiveness
Be careful not to confuse the enthalpy reduction py(or ventilation load reduction) required by ASHRAE 90.1 with “rated” effectiveness per ASHRAE 84 / AHRI 1060
Strive for equal airflows• Bring back as much exhaust air as possible
© 2012 Trane, a business of Ingersoll-Rand44
Agenda Why implement exhaust-air energy recovery?
Common air-to-air energy recovery technologiesgy y g• Coil loop
• Heat pipe
• Fixed-plate heat exchanger
• Fixed-membrane heat exchanger
• Total-energy wheel
Proper control and integration into HVAC systems
© 2012 Trane, a business of Ingersoll-Rand45
Proper control and integration into HVAC systems
Suggestions for cost-effective application
Coil loop
Energy Recovery Technology Comparison
Heat pipe
Fixed-plate heat exchanger
Fixed-membrane heat exchanger
© 2012 Trane, a business of Ingersoll-Rand46
Total-energy wheel
Coil Loop EAEA
expansionexpansionexpansionexpansiontanktank
pumppump
threethree--waywaymixing valvemixing valve
© 2012 Trane, a business of Ingersoll-Rand47
OAOA
coil loopTypical Applications When need to totally isolate
exhaust
ventilation from exhaust air
No cross contamination
Hospitals or labs with high ventilation/exhaust rates (8760 hours/year)
© 2012 Trane, a business of Ingersoll-Rand48
hours/year)
Greater benefits in heating-dominated climates intake
coil loopHow Much Energy Recovered
Typical Coil LoopSensible
50%
60%
ven
ess
8 Row 12FPI
Effectiveness
30%
40%
50%
ated
Sen
sib
le E
ffec
tiv
6 Row 10FPI
4 Row 10 FPI
35% to 55% sensible heat recovered
• Ethylene glycol (30%)
© 2012 Trane, a business of Ingersoll-Rand49
0%
20%
300 400 500 600 700
Face Velocity (FPM)
Cal
cula • Ethylene glycol (30%)
• Turbulators inside 5/8” tubes
coil loopEnergy Recovery At What Cost
Typical Coil Loop Air Pressure Drop 1.2
1.4
.g.)
8 Row 12FPIPlus Pump Energy• 4 rows = 10 ft. H2O
per Coil
0.4
0.6
0.8
1
Pre
ssu
re L
oss
(in
w.
6 Row 10FPI
4 Row 10 FPI
2
• 6 rows = 15 ft. H2O• 8 rows = 19 ft. H2O• Additional losses
(valves, pipes,run)
© 2012 Trane, a business of Ingersoll-Rand50
0
0.2
300 400 500 600 700Face Velocity (FPM)
Air
Coil Loop Considerations
Sensible recovery only, no stream-to-stream leakage, y y gducts may be separated
Ventilation load-reduction is usually too low• 10-20% in moist climates, 35-55% in dry & cold climates
Std 90.1 exceptions may allow coil loops, e.g.:
© 2012 Trane, a business of Ingersoll-Rand51
• Exception c: Systems exhausting toxic fumes
• Exception h: Systems with multiple small exhaust paths
Capacity modulation
cool EA to outside
cold OA from
Heat Pipe
via bypass dampers or tilt control
Very low cross-leakage
No pumpshot EA from
outside
© 2012 Trane, a business of Ingersoll-Rand52
inside
warm SA to inside
heat pipeHow Much Energy Recovered
Heat PipeSensible
60%
enes
s30% to 52% sensible heat recovered
Sensible Effectiveness
20%
30%
40%
50%
ed S
ensi
ble
Eff
ecti
ve7 Row 6 Row 5 Row
© 2012 Trane, a business of Ingersoll-Rand53
0%
10%
300 400 500 600 700Face Velocity (FPM)
Cal
cula
te
Typical Coil Loop 1.4
1.6
g.)
heat pipeEnergy Recovery At What Cost
Air Pressure Drop per Coil
0.4
0.6
0.8
1
1.2
1.4
Pre
ssu
re L
oss
(in
w.g
7 Row 6 Row 5 Row
© 2012 Trane, a business of Ingersoll-Rand54
0
0.2
300 400 500 600 700
Air
P
Face Velocity (FPM)
Heat Pipe Considerations
Sensible recovery only, some leakage possible,y y g pducts must be adjacent
Ventilation load-reduction is too low• 10-20% in moist climates, 30-50% in dry & cold climates
Std 90.1 exceptions may allow use of heat pipes, e.g.:
© 2012 Trane, a business of Ingersoll-Rand55
• Exception b: Uncooled spaces, heated to <60ºF
Cross-flow aluminum plates
Dimpled or channeled plates
Fixed-Plate Heat Exchanger
OAOADimpled or channeled plates
Handle high pressure up to 10” diff
High temperatures
Corrosion resistant
Capacity modulation using
© 2012 Trane, a business of Ingersoll-Rand56
Capacity modulation using face-and-bypass dampers
Little or no cross-leakage
Most susceptible to frosting
EEAA
fixed-plate heat exchangerExample AHU Layouts
EA OA OA
EA OA
EA
© 2012 Trane, a business of Ingersoll-Rand57
EA OA
20,000 cfm Heat Exchanger (AHU casing removed)
face-and-bypass
fixed-plate heat exchanger
EAEA
center bypass
face-and-bypass dampers
© 2012 Trane, a business of Ingersoll-Rand58
drain pans
OAOA
RA70°F 30% RH
OA
fixed-plate heat exchangerNon-Uniform Temperature Across Exchanger
70°F, 30% RH(37°F DPT)
coldcorner
20°F
© 2012 Trane, a business of Ingersoll-Rand59
42°F 54°F
37ºF
47ºF
fixed-plate heat exchangerWhich Face Velocity Matters?
exchanger face area
air handler
© 2012 Trane, a business of Ingersoll-Rand60
face area
80%
ss
fixed-plate heat exchangerHow Much Energy Recovered
40%
50%
60%
70%
ed
Sen
sib
le E
ffec
tive
ne
s
Air-to-Air Plate ExchangerSensible Effectiveness
60% to 70% sensible
© 2012 Trane, a business of Ingersoll-Rand61
20%
30%
300 400 500 600 700Air Handler Face Velocity (FPM)
Cal
cula
tesensible heat recovered
10,000 cfm Air Handler Example
1.6
)
fixed-plate heat exchangerEnergy Recovery At What Cost
0.6
0.8
1
1.2
1.4
essu
re L
oss
(in
w.g
.)
Air-to-Air Plate ExchangerAir Pressure Drop
© 2012 Trane, a business of Ingersoll-Rand62
0
0.2
0.4
Air
Pre
300 400 500 600 700Air Handler Face Velocity (FPM)
Fixed-Plate Considerations
Sensible recovery only, some leakage possible, ducts y y g pmust be adjacent
Ventilation load-reduction varies over wide range• 20% to 30% in moist climates is too low
• 55% to 70% in dry & cold climates is high enough
© 2012 Trane, a business of Ingersoll-Rand63
Std 90.1 exceptions may allow fixed-plate exchangers• Exception j: Systems that operate less than 20 hours
per week at design minimum OA flow
Fixed-Membrane Heat Exchanger
Membrane material in EAOA
layers
Water vapor permeable
Capacity modulation using external bypass dampers
EAOA
© 2012 Trane, a business of Ingersoll-Rand64
Little cross-leakage
Smaller cores only(500 cfm range)
OA
Fixed-Membrane Heat Exchanger
( g )
Limited fan arrangements
Low pressure differential (2 to 4 in. H2O maximum)
Large footprint required
Transitions add another
© 2012 Trane, a business of Ingersoll-Rand65
Transitions add another 1.0 to 1.5 in. H2O pressure loss (> 2000 cfm)
RA
fixed-membrane heat exchangerHow Much Energy Recovered
B k f M b
80%
ss
Bank of Membrane ExchangersSensible & Latent Effectiveness
40%
50%
60%
70%
ble
& L
aten
t E
ffec
tive
ne
s
Sensible: 62-70% Latent: 45–54%
Latent
Sensible
OA
© 2012 Trane, a business of Ingersoll-Rand66
20%
30%
300 400 500 600 700
Air Handler Face Velocity (FPM)
Sen
sib
RA10,000 cfm Air Handler Example
B k f M b 2 8
3.2
fixed-membrane heat exchangerEnergy Recovery At What Cost
Bank of Membrane ExchangersAir Pressure Drop
0 8
1.2
1.6
2.0
2.4
2.8
Pre
ssu
re L
oss
(in
w.g
.)
OA
© 2012 Trane, a business of Ingersoll-Rand67
0
0.4
0.8
300 400 500 600 700
Air
P
RA10,000 cfm Air Handler Example
Air Handler Face Velocity (FPM)
Fixed-Membrane Considerations
Total energy recovery, low leakage, adjacent ductsgy y g j
Ventilation load-reduction varies widely• 35% to 60% in moist climates
• 55% to 70% in dry & cold climates
Probably meet Std 90.1 (50%) in most locations and
© 2012 Trane, a business of Ingersoll-Rand68
Std 189.1 (60%) in some locations
Low core airflows limit unit size
Desiccant rotor rotating 20-60 rpm between exhaust and outdoor air
Total-Energy Wheel
Capacity modulation using bypass dampers
Some cross-leakage
Self cleaning (dry particles)
Less susceptible to frosting
© 2012 Trane, a business of Ingersoll-Rand69
than sensible-recovery technologies
total-energy wheelMedia Types
Aluminum Synthetic fiber Polymer
Weight heaviest Mid lightest
Bearing maintenance annual large I small none
D i t l di d b t d
© 2012 Trane, a business of Ingersoll-Rand70
Desiccant loading good best good
Corrosion resistance good best better
Common depth 6”, 8”, 12” 4”, 6” 1.5”, 3”
AHRI 1060 Directory Data
90
total-energy wheelHow Much Energy Recovered
30
40
50
60
70
80
90
Sensible Effectiveness
Latent Effectiveness
Difference Between Sensible and Latent
% E
ffec
tive
nes
s
© 2012 Trane, a business of Ingersoll-Rand71
0
10
20
0 0.2 0.4 0.6 0.8 1 1.2Pressure Drop in w.g.
%
total-energy wheelHow Much Energy Recovered
80%
ess
Sensible & Latent Effectiveness
Sensible: 60-76% Latent: 55-71%
40%
50%
60%
70%
e &
Lat
ent
Eff
ecti
ven
Latent
Sensible
© 2012 Trane, a business of Ingersoll-Rand72
20%
30%
300 400 500 600 700
Air Handler Face Velocity (FPM)
Sen
sib
le
10,000 cfm Air Handler Example
1 4
1.6
.)
total-energy wheelEnergy Recovery At What Cost
Energy WheelAir Pressure Drop
0 4
0.6
0.8
1
1.2
1.4
ress
ure
Lo
ss (
in w
.g.
© 2012 Trane, a business of Ingersoll-Rand73
0
0.2
0.4
300 400 500 600 700
Face Velocity (FPM)
Air
Pr
M di t M t h
total-energy wheelEnergy Recovery At What CostMotor Power
Media type Motor horsepower
Aluminum 1/3—5 hp
Synthetic fiber 1/4—2 hp
© 2012 Trane, a business of Ingersoll-Rand74
y
Polymer 1/80—1/3 hp
total-energy wheel: at what cost
Cross Leakage
EA RAEA RA
OA SA
cross leakage
OA SA
cross leakage
EA
EA
© 2012 Trane, a business of Ingersoll-Rand75
EA
OA
RA
SA
cross leakage
OA
RA
SA
cross leakage
total-energy wheel: at what cost
Cross Leakage
Exhaust
FA
CE
FA
CE
leakageP >0
outdoor
Exhaust Air
© 2012 Trane, a business of Ingersoll-Rand76
NON CONTACT SEAL
CONTACT SEAL
WH
EE
L F
WH
EE
L Fair
Carry Over
Outside Air Correction Factor
total-energy wheel
Cross-Leakage Measurements
Outside Air Correction Factor Ratio of outdoor air flow to supply air flow
OACF = OA cfm/SA cfm
Exhaust Air Transfer Ratio
exhaust air
10,000 cfm11,000 cfm
© 2012 Trane, a business of Ingersoll-Rand77
aust a s e at oThe percentage of supply air that is exhaust air
outdoor air
10,000 cfm11,000 cfm
1.4
1.45
1.5
total-energy wheel
Cross-Leakage Measurements
1 1
1.15
1.2
1.25
1.3
1.35
OA
CF
© 2012 Trane, a business of Ingersoll-Rand78
1
1.05
1.1
0 1 2 3 4 5Pressure Differential Leaving Supply to Entering Exhaust in. w.g.
Total Energy Wheel Considerations
Total energy recovery, must manage leakage, gy y g gadjacent ducts
Ventilation load-reduction (60% to 80% in all climates) meets Std 90.1 (50%) and Std 189.1 (60%)
Proper fan placement can control pressures to reduce t ti l l k
© 2012 Trane, a business of Ingersoll-Rand79
potential leakage
total energy wheel
Reduction in Ventilation Cooling Load:Region A “Moist”
Comparison of Energy-Recovery Technologies
coil loop
fixed-plateheat exchanger
total-energy wheel
fixed-membraneheat exchanger
© 2012 Trane, a business of Ingersoll-Rand80
% Reduction Ventilation Load
0 60 1004020 80
heat pipe
total energy wheel
Comparison of Energy-Recovery Technologies Reduction in Ventilation Heating and Cooling Load:Region B “Arid”
coil loop
fixed-plateheat exchanger
total-energy wheel
fixed-membraneheat exchanger
© 2012 Trane, a business of Ingersoll-Rand81
0 60 1004020 80
heat pipe
% Reduction Ventilation Load
Comparison of Energy-Recovery Technologies Recovery Efficiency Ratiorecovery efficiency ratio (RER): a ratio of the energy recovered divided by the energy expended in the energy recovery process*
Power required Coil loop
Heat pipe
Plate exchanger
Membranecores
Energy wheel
Fan:Pressure Loss
Fan: Leakage/Purge
BTUH / W (cooling) or W / W (heating)
© 2012 Trane, a business of Ingersoll-Rand82
Leakage/Purge
Component:Motor or Pump
*RER is defined by ASHRAE Std 84-2008 and AHRI Guideline V
Comparison of Energy-Recovery Technologies
120
140
RER Cooling: Region A “Moist”
40
60
80
100
fixed-plate
RE
R
btu
h/ W
Based on 10,000 cfm95ºF / 78ºF OA 75ºF 55%RH RA
© 2012 Trane, a business of Ingersoll-Rand83
0
20
40
250 300 350 400 450 500 550 600 650 700
fixed plateheat exchanger
coil loop
Air Handler Face Velocity (fpm)
120
140
Comparison of Energy-Recovery Technologies RER Cooling: Region B “Arid”
RE
R
btu
h/ W
40
60
80
100Based on 10,000 cfm105ºF OA 75ºF 55% RH RA
© 2012 Trane, a business of Ingersoll-Rand84
0
20
250 300 350 400 450 500 550 600 650 700
Air Handler Face Velocity (fpm)
40
COP Coefficient of Performance: Heating
120
140
Comparison of Energy-Recovery Technologies R
ER
W
/ W
40
60
80
100Based on 10,000 cfm10ºF OA 70ºF no frosting
© 2012 Trane, a business of Ingersoll-Rand85
0
20
250 300 350 400 450 500 550 600 650 700
Air Handler Face Velocity (fpm)
40
H
Heating Only or Cooling: Region B “Arid”
Installed Price Addition (AHU)
Heat Pipe
Coil LoopATA Fixed Plate HXS
ensi
ble
BT
UH
eco
vere
d
© 2012 Trane, a business of Ingersoll-Rand86
ATA Fixed-Plate HX
Energy Wheel
$/S
Re
0 5000 10000 15000 20000 25000 30000Ventilation Airflow CFM
UH
Cooling: Region A “Moist”
Installed Price Addition (AHU)ta
l Co
olin
g B
TU
ove
red
Heat PipeCoil LoopATA Fixed-Plate HX
© 2012 Trane, a business of Ingersoll-Rand87
0 5000 10000 15000 20000 25000 30000Ventilation Airflow CFM
$/To
tR
eco ATA Fixed-Plate HX
Energy Wheel
Conclusion: Which technology? Is cross leakage a concern?
• Toxic, fume hoods, isolation rooms, etc. Coil loop Coil loop
• Animal laboratory, natatorium Fixed-plate HX, coil loop, heat pipe
© 2012 Trane, a business of Ingersoll-Rand88
Conclusion: Which technology? Comfort cooling/heating application
• Dry or arid climate Fixed plate heat exchanger Fixed-plate heat exchanger
• Humid or mixed climate Total-energy wheel
• Reduced footprint required Coil loop, heat pipe
© 2012 Trane, a business of Ingersoll-Rand89
Agenda Why implement exhaust-air energy recovery?
Common air-to-air energy recovery technologiesgy y g
Proper control and integration into HVAC systems• On/off
• Capacity modulation
• Frost prevention
Suggestions for cost-effective application
© 2012 Trane, a business of Ingersoll-Rand90
BAROMETRIC PRESSURE: 28.821 in. HG
50
55
40
45
50
THAL
PY -
Btu
per l
b. o
f dry
air
and
asso
ciate
d m
oistu
reW
ET B
ULB
TEM
PERA
TURE
- °F
130
140
150
160
170
180
190
200
UN
D O
F D
RY
AIR
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
75
80
85
0.55
0.50
0.45
0.40
WET BULB TEMPERATURE - °F
75
80
85
90
14
14.8
15.0
15.2
15.4
15.6
BAROMETRIC PRESSURE: 28.821 in. HG
Atlanta, Georgiaweekdays, 6 AM to 6 PM
Weather Hours54 to 4948 to 4342 to 3736 to 3130 to 2524 to 1918 to 1312 to 76 to 1
40
45
ENTH
ALPY
- Bt
u pe
r lb.
of d
ry a
ir an
d as
soci
ated
moi
stur
e
15
20
25
30
35
ENT
50
60
70
80
90
100
110
120
130
HU
MID
ITY
RAT
IO (o
r Spe
cific
Hum
idity
) GR
AIN
S O
F M
OIS
TUR
E PE
R P
OU
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
VAPO
R P
RES
SUR
E - I
NC
HES
OF
MER
CU
RY
45
50
55
60
65
70
DEW
PO
INT
TEM
PER
ATU
RE
- °F
1.000.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
HE
AT
RA
TIO
= Q
s / Q
t
40%
50%
60%
70%
80%
90%
45
50
55
60
65
70
13.6
13.8
14.0
14.2
14.4
4.6
Weather Hours54 to 4948 to 4342 to 3736 to 3130 to 2524 to 1918 to 1312 to 76 to 1 EA
© 2012 Trane, a business of Ingersoll-Rand91
30 40 50 60 70 80 90 100 110 115DRY BULB TEMPERATURE - °F
10 15 20 25
30
35
ENTHALPY - Btu per lb. of dry air and associated moisture
10
0
10
20
30
40
0.05
0.10
0.15
0.20
0.25
0 10
20
25
30
35
40
Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com
STANDARD AIR
SE
NS
IBL
E H
10% RELATIVE HUMIDITY
20%
30%
20
25
3032
35
40
13.0
13.2
13.4
Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com
Control During Mild Weather
RA7,000 cfm
70°FEA
20,000 cfmwheel ON(full capacity) cooling coil ON
(438 MBh)
RRA
© 2012 Trane, a business of Ingersoll-Rand92
SAOA10,000 cfm 30,000 cfm
68°F65°F 55°F55°F
Control During Mild Weather
7,000 cfm70°F
EA RA
20,000 cfmwheel OFFcooling coil ON(308 MBh)
RRA
© 2012 Trane, a business of Ingersoll-Rand93
SAOA10,000 cfm 30,000 cfm
65°F55°F 55°F55°F
Control During Mild Weather
27,000 cfm70°F
EA RA
0 cfmwheel OFFcooling coil OFF(0 MBh)
RRA
© 2012 Trane, a business of Ingersoll-Rand94
SAOA30,000 cfm 30,000 cfm
55°F55°F 55°F55°F
airside economizing
On/Off Control Methods
Coil loop Turn off pump
Heat pipe
Fixed-plate heat exchanger
Fixed-membrane heat exchanger
Face-and-bypass dampers
© 2012 Trane, a business of Ingersoll-Rand95
Fixed membrane heat exchanger
Total-energy wheel Turn off wheel
EAEAface-and-bypass d EAEA
center bypass
dampers
OAOA
© 2012 Trane, a business of Ingersoll-Rand96
OAOA
On/Off Control Methods
Coil loop Turn off pump
Heat pipe
Fixed-plate heat exchanger
Fixed-membrane heat exchanger
Face-and-bypass dampers Some use solenoid valve(s)
Face-and bypass dampers
Face-and-bypass dampers
© 2012 Trane, a business of Ingersoll-Rand97
Fixed membrane heat exchanger
Total-energy wheel
Face and bypass dampers
Turn off wheel
Control During Heating
7,000 cfm70°F
EA RA
8,000 cfmwheel ON(full capacity) cooling coil ON
(87 MBh)
RRA
© 2012 Trane, a business of Ingersoll-Rand98
SAOA10,000 cfm 18,000 cfm
64°F60°F 60°F(SAT reset)
40°F
Control During Heating
7,000 cfm70°F
EA RA
8,000 cfmwheel OFFheating coil ON(131 MBh)
RRA
© 2012 Trane, a business of Ingersoll-Rand99
SAOA10,000 cfm 18,000 cfm
53°F40°F 60°F(SAT reset)
40°F
Control During Heating
7,000 cfm70°F
EAmodulate EA bypass dampers
RA
8,000 cfmwheel ON(partial capacity)
both coils OFF
RRA
© 2012 Trane, a business of Ingersoll-Rand100
SAOA10,000 cfm 18,000 cfm
60°F52°F 60°F(SAT reset)
40°F
Capacity Modulation Methods
Coil loop Three-way mixing valve Vary pump speed
Heat pipe
Fixed-plate heat exchanger
Face-and-bypass dampers Some use solenoid valve(s) Tilt mechanism
Face-and-bypass dampers
© 2012 Trane, a business of Ingersoll-Rand101
Fixed-membrane heat exchanger
Total-energy wheel
Face-and-bypass dampers
Exhaust-side bypass damper Vary wheel speed
wheel
Comparison of Capacity Control Methods
90%
100%
aci
ty
Bypass Speed
30%
40%
50%
60%
70%
80%
90%
axim
um
Rec
ove
ry C
apa
bypass control
speed control Bypass control
Speed control
Cost
Control
Energy
M t d t
© 2012 Trane, a business of Ingersoll-Rand102
0%
10%
20%
0%10%20%30%40%50%60%70%80%90%100%
%
M
%VFD Speed or % Bypass Closed Min Speed / Position
Motor duty
hu
mFrosting
midity ratio, grains/lb of drEAEA'
sensible-energy recoverywater vapor condensing
on exhaust-side coil
© 2012 Trane, a business of Ingersoll-Rand103
ry air
dry-bulb temperature, F
EAEA'
OA OA'
hu
m
frosting
Total- vs. Sensible-Energy Recovery
midity ratio, grains/lb of drEA
EA'EA'
sensible-energy recovery
© 2012 Trane, a business of Ingersoll-Rand104
ry air
dry-bulb temperature, F
EA
OAtotal-energy recovery
EA
Frost Prevention MethodsCoil loop Three-way mixing valve
Heat pipe
Fixed-plate heat exchanger
Fixed membrane heat exchanger
Face-and-bypass dampers
Frost damper
Face and bypass dampers
© 2012 Trane, a business of Ingersoll-Rand105
Fixed-membrane heat exchanger
Total-energy wheel
Face-and-bypass dampers
Supply-side bypass damper
RA
70°F, 30% RHOA
20°FRA
70°F 30% RHOA
20°F
Frost Avoidance Damper
fixed-plate heat exchanger
Frost Prevention
(37 F DPT)
coldcorner
20 F 70 F, 30% RH(37 F DPT)
20 F
coldcorner
DAMPER
© 2012 Trane, a business of Ingersoll-Rand106
< 32ºF
36°F 54°F
31ºF
41ºF45°F 45°F
43ºF
47ºF
>32ºF
fixed-plate heat exchanger
Frost Prevention
Fixed-plate (sensible) heat exchangers begin to p ( ) g gexperience frosting when entering OA drops < 25°F
Use frost damper to minimize frosting(keeps higher temperature in the “cold corner”)
© 2012 Trane, a business of Ingersoll-Rand107
Frost Prevention MethodsCoil loop Three-way mixing valve
OA or EA preheat
Heat pipe
Fixed-plate heat exchanger
Fixed membrane heat exchanger
Face-and-bypass dampers OA or EA preheat
Frost damper OA or EA preheat
Face and bypass dampers
© 2012 Trane, a business of Ingersoll-Rand108
Fixed-membrane heat exchanger
Total-energy wheel
Face-and-bypass dampers OA or EA preheat
Supply-side bypass damper OA or EA preheat
180
160
140
120
hu
mid
ity raTotal-Energy Wheel in aMixed-Air VAV System
120
100
80
60
40
atio
, grain
s/lb o
f dry air
EAEAEAEA
wheel on (cooling)bypass dampers closed
wheel on (heating)modulate bypass damperto avoid overheating
© 2012 Trane, a business of Ingersoll-Rand109
40
20
11030 40 50 60 70 80 10090dry-bulb temperature, °F
DBTSAwheel offbypass dampers open
to avoid overheating
System Control Modes
Air-to-Air Energy Recovery in HVAC Systems, Trane application manual, SYS-APM003-EN
Sensible- or total-energy recovery
Mixed-air or dedicated OA system
Constant- or variable-air volume
DBT- or enthalpy-based control
Airside economizers
© 2012 Trane, a business of Ingersoll-Rand110
Airside economizers
Energy recovery capacity control
Frost prevention
Agenda Why implement exhaust-air energy recovery?
Common air-to-air energy recovery technologiesgy y g
Proper control and integration into HVAC systems
Suggestions for cost-effective application
© 2012 Trane, a business of Ingersoll-Rand111
Suggestions
ASHRAE 90.1-2010 (and 189.1-2011) requires ( ) qexhaust-air energy recovery in more applications
Total-energy recovery transfers both sensible heat and water vapor (latent heat)• Allows for larger cooling plant reductions
© 2012 Trane, a business of Ingersoll-Rand112
• Less susceptible to frost, so greater heating energy savings
Suggestions
Maximize energy recovery effectivenessgy y• Centralize exhaust to better balance airflows and
maximize recovery
• Minimize cross-leakage with fan placement
© 2012 Trane, a business of Ingersoll-Rand113
• Toilet exhaust air is isolated from return air
• Divider panel divides toilet and
maximizing energy recovery
Dual Exhaust Energy Recovery
• Divider panel divides toilet and system exhaust air
• Toilet exhaust enters the first portion of the energy wheel
• System exhaust enters second portion of wheel
© 2012 Trane, a business of Ingersoll-Rand114
portion of wheel
• System exhaust air purges wheel of toilet exhaust air before rotating to the Supply AirToilet Exhaust Air Flow = Fixed amount set by code requirements
System Exhaust Air Flow = Varies to meet building pressure requirements
Toilet Exhaust Airflow
Toilet + System Exhaust Airflow
Exhaust FanFan speed modulates to control building pressure
P
DEER Damper Control
System Exhaust Airflow
Supply Airflow
pressure
VFD
Toilet DamperTraq damper modulates to maintain code required toilet exhaust air flow
Balancing DamperWhen toilet damper is
© 2012 Trane, a business of Ingersoll-Rand115
Ventilation Airflow
100% open, balancing damper modulates from minimum position to close to maintain toilet exhaust air flow
ASHRAE Standard 62.1-2010, Section 5.16.3.2.5
Recirculation of Toilet Exhaust
“Class 2 air [which includes air from restrooms] shall not be [ ]recirculated or transferred to Class 1 spaces.
Exception: When using an energy recovery device, recirculation from leakage, carryover, or transfer from the exhaust side of the energy recovery device is permitted. Recirculated Class 2 air shall not exceed 10% of the outdoor air intake flow ”
© 2012 Trane, a business of Ingersoll-Rand116
shall not exceed 10% of the outdoor air intake flow.
Exhaust Air Transfer Ratio (EATR)
Defined by ASHRAE Standard 84 Defined by ASHRAE Standard 84
Certified by AHRI Standard 1060
EATR ≤ 10%
X4 X3
XX1
OA
EAEA
© 2012 Trane, a business of Ingersoll-Rand117
X2X1
Suggestions
Proper control is very importantp y p• Turn device OFF during mild weather to
avoid wasting energy
• Modulate capacity during cold weather to prevent over-heating
• Include bypass dampers to enable
© 2012 Trane, a business of Ingersoll-Rand118
• Include bypass dampers to enable economizing in mixed-air systems
• Don’t forget about frost prevention
Suggestions
Specify/purchase AHRI-certified p y pcomponents• Trustworthy performance data,
fewer third-party or field performance tests
• More accurate sizing for improved
© 2012 Trane, a business of Ingersoll-Rand119
• More accurate sizing for improved design and application of air-handling equipment
references for this broadcast
Where to Learn More
© 2012 Trane, a business of Ingersoll-Rand120
www.trane.com/EN
• ASHRAE Standards 189.1, 90.1, 62.1• High-performance VAV Systems• Chilled-water plants
www.trane.com/ENL Past program topics include:
Chilled water plants• Air distribution• WSHP/GSHP systems• Control strategies• USGBC LEED®
• Energy and the environment• Acoustics
V til ti
© 2012 Trane, a business of Ingersoll-Rand121
• Ventilation• Dehumidification• Ice storage• Central geothermal systems
LEED Continuing Education Courseson-demand, no charge, 1.5 CE credits
ASHRAE Standards 62.1 and 90.1 and VAV Systems
ASHRAE St d d 62 1 V til ti R t P d ASHRAE Standard 62.1: Ventilation Rate Procedure
ASHRAE Standard 90.1-2010
ASHRAE Standard 189.1-2011
High-Performance VAV Systems
Dedicated Outdoor Air Systems
© 2012 Trane, a business of Ingersoll-Rand122
Ice Storage Design and Control
Energy Saving Strategies for WSHP/GSHP Systems
www.trane.com/ContinuingEducation
2013 Engineers Newsletter Live Programs
Single-zone VAV Systemsg y
ASHRAE Standard 62.1
Variable-speed Chiller Plant Operation
© 2012 Trane, a business of Ingersoll-Rand123
Air-to-Air Energy Recovery
Industry Publications Air‐Conditioning, Heating, and Refrigeration Institute (AHRI). ANSI/AHRI Standard 1060‐2011: Performance Rating of Air‐to‐Air Heat Exchangers for Energy Recovery Equipment. Available at www.ahrinet.org Air‐Conditioning, Heating, and Refrigeration Institute (AHRI) Directory of Certified Product Performance available at www.ahridirectory.org American Society of Heating, Refrigerating, and Air‐Conditioning Engineers (ASHRAE). ANSI/ASHRAE/IESNA Standard 90.1‐2010: Energy Standard for Buildings Except Low‐Rise Residential Buildings. Available at www.ashrae.org/bookstore American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE). Standard 90.1‐2010 User’s Manual. Available at www.ashrae.org/bookstore American Society of Heating, Refrigerating, and Air‐Conditioning Engineers (ASHRAE). ANSI/ASHRAE/USGBC/IES Standard 189.1‐2011: Standard for the Design of High‐Performance Green Buildings Except Low‐Rise Residential Buildings. Available at www.ashrae.org/bookstore
Trane Application Manual Murphy, J. and B. Bradley. Air‐to‐Air Energy Recovery in HVAC Systems, application manual SYS‐APM003‐EN, 2008. Order from www.trane.com/bookstore
Analysis Software Trane Air‐Conditioning and Economics (TRACE™ 700). Available at www.trane.com/TRACE
October 2012
Air‐to‐Air Energy Recovery
Bibliography
©2012 Trane Engineers Newsletter LIVE: Air-to-Air Energy Recovery