Upload
others
View
9
Download
0
Embed Size (px)
Citation preview
MuntersHeat Exchangers
Brad Perdew
Applications Engineer
8/27/12
DOAS Configurations
Cheryl HughesRegional Sales Manager
October 11, [email protected]
• Purpose of Dedicated Outside Air Systems
• Review Building Loads
• Talking Dew Point is Critical
• How DOAS is Applied
• Munters Core Components
• Munters DOAS Configurations
• Munters Cost to Operate Spreadsheet
Munters DOAS Configurations Presentation
•ASHRAE recommends decoupling sensible and latent loads
•ASHRAE recommends lower delivered dew points
–Lower than the original “Neutral Air Unit”
–Lower than standard packaged DX or chilled water can deliver
•Outside air is good, but consumes a lot of energy to treat
•90.1 wants to reduce energy
•LEED makes you prove you have reduced energy
Purpose of DOAS
Sensible Loads Have Reduced –Less Cooling Required, Less “Reheat” Available
= Reduced Lighting Load
= Reduced Solar Load
= Improved Envelope
•Outdoor Air
•People
• Infiltration
•Operations
No Reduction in Moisture Load –Requires Active Dehumidification
Typical Buildings – Design Dew Points
Building Space Served Dew Point Control
Meeting Space Single 51-55°F Loose
Grocery Store Single 48-52°F Medium
Pharmaceuticals Single 49-56°F Tight
Hotel/Condo Multiple 54-56°F Loose
Office Multiple 52-55°F Loose
Classrooms Multiple 52-55°F Loose
Healthcare Depends 42-52°F Depends
Supply Air at the Correct Dew Point
SPACE DEW POINT VS. OUTDOOR AIR CFM DELIVERED PER PERSON
45.050.055.060.0
65.070.075.080.0
0 10 20 30 40
O/A CFM DELIVERED PER PERSON
SP
AC
E D
EW
PO
INT
40 DP
45 DP
50 DP
55 DP
60 DP
Chart accounts for internal latent load of occupant s at 200 Btu/hr/person
Multiple DOAS Options
•Different DOAS technologies
•Different system combos and
methods of laying out DOAS
•Standard or custom solutions for
every application
SENSIBLE ENERGY RECOVERY
DEHUMIDIFICATION& TOTAL ENERGY
RECOVERY
EVAPORATIVE COOLING
EVAPORATIVE COOLING& SENSIBLE ENERGY RECOVERY
Munters Products
Core Components
• Focus on Humidity Control
• Over-Cool & Reheat
• Wringer Cycle
• Cooling Coil Surrounded by Single Heat
Exchanger
• Active Desiccant
• Reactivated by external source of heat
• Reactivated using “site recovered” energy
• Focus on Energy Recovery
• Wheels – Enthalpy or Sensible
• Heat pipes
• Plates – Counter-flow or Crossflow
• EPX – Polymer Tubes
Munters DOAS Products
●With Exhaust Air Energy Recovery
– Sensible Heat Recovery
– Total Heat Recovery
– Sensible Wringer Plus
– Total Wringer Plus
– DryCool ERV
– DDS (Config 3 & 4)
●Without Exhaust Air Energy Recovery
– Cool-Reheat
– Wringer
– DryCool / HCU
– DDS (Config 1,2 & 5)
– HCD
– ICA
OA S/A
DX Cooling Coil Hot Gas Reheat Supply FanCompressors
Old Version of “Neutral” air to space 75°F at 55°F dewpoint = 50% rh
55°F 75°F
OA S/A
Now DOAS Should Deliver “Over Dried” Air to Space 75°F at 45°F dewpoint = 35% rh
45°F 75°F
DX Cooling Coil Hot Gas Reheat Supply FanCompressors
Cool-Reheat (Brute Force)
●Cool air to desired leaving dew point and then reheat it to “Space
Neutral” temperature
●Reheat must not be a "new" energy source per 90.1
– Packaged DX unit (with Hot Gas Reheat)
●Highly competitive, Munters rarely sells
Cool Reheat
Outside
Air
SA
Over-Cool & Reheat (Common Selection)
60 ton CU47.5F dp
● Introduced by Des Champs in 1980 as a patented process surrounding a dehumidification coil
with a single energy recovery device
● First pass across energy recovery device pre-cools humid air before coil . . . Reducing
refrigeration requirements
● Second pass across energy recovery device reheats leaving air, reducing or eliminating the need
for supplemental reheat
● Achievable dew point limited by coil temperature
Sensible Heat
Exchanger
Outside
Air
Cool Reheat
Sensible Heat
Exchanger
Outside
Air
Cool Reheat
Wringer
SA
Wringer
50 ton CU46.4F dp
Exhaust Air Energy Recovery
Energy
Recovery
Device
CW Coil
DX (AC/WC/WSHP)
Reheat
Outside
Air
Return/Exhaust Air
• Pre-conditions OA with energy recovery device before cooling to desired
dew point and then reheat it to space neutral temperature
SA
EA
Special WARNING About
Energy Recovery System Performance!
AIR CAPACITYCFM SUMMER WINTER SUPPLY AIR FAN EXHAUST AIR FAN
SUPPLY EXHAUST (db/RH, F) (db/RH, F) ESP TSP HP ESP TSP HPRTU-1 PVR-12 11,600 11,600 75/50% 72/- 1.0 4.2 15.0 1.0 2.7 10.0
RTU-2 PVR-6 6,100 6,100 75/50% 72/- 1.0 4.0 7.5 1.0 2.9 5.0
RTU-3 PVR-4 4,450 4,450 75/50% 72/- 1.0 4.3 5.0 1.0 2.9 5.0
ROTARY HXR HEAT EXCHANGER Ind. Gas SupplyE.A.T. L.A.T. E.A.T L.A.T. TOTAL E.A.T L.A.T. Heat MBH Air
(db/wb, F) (db/wb, F) (db/wb, F) (db/wb, F) MBH (db/wb, F) (db, F) (Output) (db, F) Accessories90/73 77.6/66.8 80.6/67.7 58/58 462.1 0/- 38.0 640.0 88.9
90/73 77.8/66.8 80.8/67.7 59/59 243.0 0/- 38.0 160.0 62.2
90/73 78.1/67 81.1/67.9 61/61 180.4 0/- 38.0 120.0 62.9
SUPPLY AIR, SUMMER
DX COIL
SUPPLY AIR, WINTER
TAG MODEL NUMBERRETURN AIR TEMP
Critical Relationship
Exhaust Air Energy Recovery
50 ton CU46.5F dp
Wringer Plus
Cool
Enthalpy Wheel
Heat Pipe, Plate or EPX
Sensible Wheel
Heat Pipe or Plate
Reheat
Outside
Air
Return/Exhaust Air
• Adds exhaust air energy recovery, sensible or total, to a Wringer
SA
EA
Wringer Plus
30 ton CU46.2F dp
• Outside air first passes the pre-cool coil to < 60°F saturated
• The pre-cooled air then passes thru the desiccant wheel to continue drying the air to ~45°Fdp, the
dehumidification process simultaneously raises the dry bulb temperature to ~75°F
• Combining pre-cooling with active desiccant dehumidification reduces refrigeration requirements
by ~40%
• Outside air for reactivation is heated by a condenser coil, the rest of the condenser heat is rejected
to atmosphere
Desiccant
DH Wheel
SA
EA
Cool
Outside
Air
Outside Air
DryCool – Hybrid Cooling plus Active Desiccant DH
SA
EA
DryCool Standard / HCU
40 tons precooling
43.6°F dp
no. 24
DryCool Chilled Water
One 10 ton DX ckt
45.3°F dp
Desiccant
DH Wheel
Cool
Outside
Air
Return/
Exhaust AirReact
Condenser Coil ACondenser
Coil B
Energy
Recovery Wheel
DryCool ERV
• Adds exhaust air energy recovery to DryCool unit
• Suitable for indoor installations
Outside
Air
SA
DryCool ERV
26 ton CU43.7°F dp
Enthalpy Wheel + Desiccant
Cost to Operate Comparison
Munters DOAS Presentation Recap
• Dedicated Outside Air Systems should be considered for all occupied spaces to provide adequate ventilation and meet codes
• Properly conditioning outside air takes a lot of energy, it makes sense to consider all ways to reduce operating costs
• Sizing and operating DOAS to maintain proper humidity control is crucial to occupant comfort and integrity of the building envelope
• Munters experience in humidity control plus Des Champs experience in energy recovery provide customers with a wide range of product options and expertise
• Each Munters system design has advantages and limitations to consider and can be compared side by side to aid in the decision making process
Questions