MuntersHeat Exchangers

Brad Perdew

Applications Engineer

8/27/12

DOAS Configurations

Cheryl HughesRegional Sales Manager

October 11, 2016cheryl.hughes@munters.com

• 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