ASHRAE Journal - September 2020 - 44

TECHNICAL FEATURE

Wet
-B

200

Tem
p

erat

ure-

°F

180

160

80

140

120
70

RH

60%

RH

100

80

40%

60

Room Target Range 70°F - 75°F DB
DB 40% - 60% RH

60

50
Room Load

45°F DP/DB/WB

20

bati

30
23°F

cH

umi

dific

ati o

20

ASHRAE JOURNAL

45°F DP

FW

B

30

40

20

ashrae.org

20°F DP

Climate Zone 3
50

SEPTEM BER 2020

40

Outdoor Air Hydration

n

Climate Zone 2
60
70
Dry-Bulb Temperature (°F)

During the spring and fall outdoor air often contains
large amounts of airborne pollens that can cause allergies in susceptible humans. Pollen ranges in size from
10 microns to 100 microns and should be removed
from the outdoor air before it is supplied to the
building.
When wet, the 12 in. (305 mm) deep rigid media
pads in the AC/H have 90% or better removal efficiency
of pollen spores larger than 10 microns in diameter.
AC/Hs are often referred to as "wet scrubbers."
The use of air-to-air heat exchangers (sensible heat
wheels) and rigid media AC/Hs are key to the success
of this system including ease of control, environmental health, energy savings and low maintenance.
Refrigerant 718, better known by its chemical formula
H2O, has zero global warming potential (GWP), is inexpensive, nonflammable, nontoxic and is a sustainable
44

55°

Heat Recovery

Climate Zone 1
10

Adia

40

Seattle Winter Design
23°F DB/22.1°F WB

Humidity Ratio-Grains of Moisture Per Pound of Dry Air

FIGURE 7 Seattle TMY2, hour by hour, typical year ambient conditions
overlay on Figure 3. In Climate Zone 1 there are zero annual hours.
There are 3,836 hours per year between 23°F DB and 45°F WB. There
are 3,231 annual hours from 45°F WB to 55°F WB, or a total of 80.7%
of the year, that the adiabatic cooler/humidifier can furnish beneficial
outdoor air humidification without the assistance of the hot water coil
in the central station unit and provide energy-efficient sensible cooling
without refrigeration.

ulb

80

90

100

110

120

refrigerant. Water vapor released to the atmosphere
returns to the earth as rain, sleet or snow.

Conclusions
Through the 50 years that VAV systems have been used
in the HVAC industry for commercial building air-conditioning systems, the use of airside economizers to save
heating and cooling energy have often compromised
the fresh air fraction being furnished to meet code or
ASHRAE Standard 62.1 and have wasted energy.26 Dry
indoor conditions in winter have led to an increase
in respiratory infections and the spread of airborne
pathogens such as the influenza virus. IEQ and VAV had
become two mutually exclusive acronyms.
This VAV design offers the hydration of all outdoor
air in cold climates and offers resiliency in the face of
climate change. In the future, more and more annual



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ASHRAE Journal - September 2020

Table of Contents for the Digital Edition of ASHRAE Journal - September 2020

Contents
ASHRAE Journal - September 2020 - Intro
ASHRAE Journal - September 2020 - Cover1
ASHRAE Journal - September 2020 - Cover2
ASHRAE Journal - September 2020 - 1
ASHRAE Journal - September 2020 - Contents
ASHRAE Journal - September 2020 - 3
ASHRAE Journal - September 2020 - 4
ASHRAE Journal - September 2020 - 5
ASHRAE Journal - September 2020 - 6
ASHRAE Journal - September 2020 - 7
ASHRAE Journal - September 2020 - 8
ASHRAE Journal - September 2020 - 9
ASHRAE Journal - September 2020 - 10
ASHRAE Journal - September 2020 - 11
ASHRAE Journal - September 2020 - 12
ASHRAE Journal - September 2020 - 13
ASHRAE Journal - September 2020 - 14
ASHRAE Journal - September 2020 - 15
ASHRAE Journal - September 2020 - 16
ASHRAE Journal - September 2020 - 17
ASHRAE Journal - September 2020 - 18
ASHRAE Journal - September 2020 - 19
ASHRAE Journal - September 2020 - 20
ASHRAE Journal - September 2020 - 21
ASHRAE Journal - September 2020 - 22
ASHRAE Journal - September 2020 - 23
ASHRAE Journal - September 2020 - 24
ASHRAE Journal - September 2020 - 25
ASHRAE Journal - September 2020 - 26
ASHRAE Journal - September 2020 - 27
ASHRAE Journal - September 2020 - 28
ASHRAE Journal - September 2020 - 29
ASHRAE Journal - September 2020 - 30
ASHRAE Journal - September 2020 - 31
ASHRAE Journal - September 2020 - 32
ASHRAE Journal - September 2020 - 33
ASHRAE Journal - September 2020 - 34
ASHRAE Journal - September 2020 - 35
ASHRAE Journal - September 2020 - 36
ASHRAE Journal - September 2020 - 37
ASHRAE Journal - September 2020 - 38
ASHRAE Journal - September 2020 - 39
ASHRAE Journal - September 2020 - 40
ASHRAE Journal - September 2020 - 41
ASHRAE Journal - September 2020 - 42
ASHRAE Journal - September 2020 - 43
ASHRAE Journal - September 2020 - 44
ASHRAE Journal - September 2020 - 45
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ASHRAE Journal - September 2020 - 48
ASHRAE Journal - September 2020 - 49
ASHRAE Journal - September 2020 - 50
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ASHRAE Journal - September 2020 - 53
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ASHRAE Journal - September 2020 - 58
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ASHRAE Journal - September 2020 - 60
ASHRAE Journal - September 2020 - 61
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ASHRAE Journal - September 2020 - 63
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ASHRAE Journal - September 2020 - 65
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ASHRAE Journal - September 2020 - 68
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ASHRAE Journal - September 2020 - 70
ASHRAE Journal - September 2020 - 71
ASHRAE Journal - September 2020 - 72
ASHRAE Journal - September 2020 - 73
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ASHRAE Journal - September 2020 - 76
ASHRAE Journal - September 2020 - 77
ASHRAE Journal - September 2020 - 78
ASHRAE Journal - September 2020 - 79
ASHRAE Journal - September 2020 - 80
ASHRAE Journal - September 2020 - Cover3
ASHRAE Journal - September 2020 - Cover4
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