ASHRAE Journal - April 2020 - 70

COLUMN ENGINEERS NOTEBOOK

demonstrating this relationship.
Optimizing chilled water ΔT has an
immediate benefit to chilled water
pumping system sizing and power
requirements.
It must be emphasized that a high
ΔT is not something that the central
plant can "make happen" through
control logic at the plant. Rather, ΔT
is determined by the buildings, and
the plant can only react to the flow
buildings require and the ΔT they
produce. While low ΔT can be caused
by many factors,1 - 4 one common
error that is readily avoided is incorrectly selecting coils.
The author recommends using
Taylor's6 recommendation of
selecting every coil at the maximum density allowed by ASHRAE
Standard 62.1's cleanability limit,
typically eight rows and 10 fins per
in. (~3.9 fins per cm). This approach
will generally yield the highest
chilled water ΔT performance and
the most flexibility to accommodate
varying coil conditions.
Campuses that use thermal energy
storage (TES) systems benefit greatly
from high ΔT, as the cooling capacity of the storage tank is directly
proportional to the ΔT at which
the campus chilled water system
operates. TES systems consist of
large volumes of chilled water that
are "charged" to a relatively low
chilled water temperature, e.g., 39°F
(3.9°C) to maximize the capacity and
benefit from the investment placed
in these storage tanks (Figure 4). The
campus chilled water distribution
pump differential pressure sensor
that controls secondary pump speed
is placed at the plant, but its setpoint
is reset by the output of control
loops, maintaining a slight positive
pressure at each building served.
70

ASHRAE JOURNAL

ashrae.org

FIGURE 4 Example campus TES system.

ΔP
(Campus Connection)
VFD

VFD

Secondary Plant
Pumps

Thermal Energy Storage Tank
Primary Plant
Pumps
VFD
Chiller
VFD
Chiller

FIGURE 5 Campus chilled water decoupled direct building connection aka "bypass/tempering" building connection example.

VFD

VFD

Campus
CHWS

ΔP (Campus

C
ΔP
(Building Demand)

Btu Meter

Connection)

Campus
CHWR

Building
CHWS

T

T
FM
T

Existing TES systems designed
based on lower ΔT criteria can have
their cooling capacity expanded by
an increase in chilled water return
temperature; increasing ΔT performance can increase the resilience
of this utility. Conversely, TES

APRI L 2020

C
C

C

Building
CHWR

systems can also have their effective cooling capacity diminished by
a decrease in chilled water return
temperature, so designing for and
maintaining high chilled water ΔT
is essential to achieve optimum
performance.



https://www.ashrae.org/

ASHRAE Journal - April 2020

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

Contents
ASHRAE Journal - April 2020 - Intro
ASHRAE Journal - April 2020 - Cover1
ASHRAE Journal - April 2020 - Cover2
ASHRAE Journal - April 2020 - 1
ASHRAE Journal - April 2020 - Contents
ASHRAE Journal - April 2020 - 3
ASHRAE Journal - April 2020 - 4
ASHRAE Journal - April 2020 - 5
ASHRAE Journal - April 2020 - 6
ASHRAE Journal - April 2020 - 7
ASHRAE Journal - April 2020 - 8
ASHRAE Journal - April 2020 - 9
ASHRAE Journal - April 2020 - 10
ASHRAE Journal - April 2020 - 11
ASHRAE Journal - April 2020 - 12
ASHRAE Journal - April 2020 - 13
ASHRAE Journal - April 2020 - 14
ASHRAE Journal - April 2020 - 15
ASHRAE Journal - April 2020 - 16
ASHRAE Journal - April 2020 - 17
ASHRAE Journal - April 2020 - 18
ASHRAE Journal - April 2020 - 19
ASHRAE Journal - April 2020 - 20
ASHRAE Journal - April 2020 - 21
ASHRAE Journal - April 2020 - 22
ASHRAE Journal - April 2020 - 23
ASHRAE Journal - April 2020 - 24
ASHRAE Journal - April 2020 - 25
ASHRAE Journal - April 2020 - 26
ASHRAE Journal - April 2020 - 27
ASHRAE Journal - April 2020 - 28
ASHRAE Journal - April 2020 - 29
ASHRAE Journal - April 2020 - 30
ASHRAE Journal - April 2020 - 31
ASHRAE Journal - April 2020 - 32
ASHRAE Journal - April 2020 - 33
ASHRAE Journal - April 2020 - 34
ASHRAE Journal - April 2020 - 35
ASHRAE Journal - April 2020 - 36
ASHRAE Journal - April 2020 - 37
ASHRAE Journal - April 2020 - 38
ASHRAE Journal - April 2020 - 39
ASHRAE Journal - April 2020 - 40
ASHRAE Journal - April 2020 - 41
ASHRAE Journal - April 2020 - 42
ASHRAE Journal - April 2020 - 43
ASHRAE Journal - April 2020 - 44
ASHRAE Journal - April 2020 - 45
ASHRAE Journal - April 2020 - 46
ASHRAE Journal - April 2020 - 47
ASHRAE Journal - April 2020 - 48
ASHRAE Journal - April 2020 - 49
ASHRAE Journal - April 2020 - 50
ASHRAE Journal - April 2020 - 51
ASHRAE Journal - April 2020 - 52
ASHRAE Journal - April 2020 - 53
ASHRAE Journal - April 2020 - 54
ASHRAE Journal - April 2020 - 55
ASHRAE Journal - April 2020 - 56
ASHRAE Journal - April 2020 - 57
ASHRAE Journal - April 2020 - 58
ASHRAE Journal - April 2020 - 59
ASHRAE Journal - April 2020 - 60
ASHRAE Journal - April 2020 - 61
ASHRAE Journal - April 2020 - 62
ASHRAE Journal - April 2020 - 63
ASHRAE Journal - April 2020 - 64
ASHRAE Journal - April 2020 - 65
ASHRAE Journal - April 2020 - 66
ASHRAE Journal - April 2020 - 67
ASHRAE Journal - April 2020 - 68
ASHRAE Journal - April 2020 - 69
ASHRAE Journal - April 2020 - 70
ASHRAE Journal - April 2020 - 71
ASHRAE Journal - April 2020 - 72
ASHRAE Journal - April 2020 - 73
ASHRAE Journal - April 2020 - 74
ASHRAE Journal - April 2020 - 75
ASHRAE Journal - April 2020 - 76
ASHRAE Journal - April 2020 - 77
ASHRAE Journal - April 2020 - 78
ASHRAE Journal - April 2020 - 79
ASHRAE Journal - April 2020 - 80
ASHRAE Journal - April 2020 - 81
ASHRAE Journal - April 2020 - 82
ASHRAE Journal - April 2020 - 83
ASHRAE Journal - April 2020 - 84
ASHRAE Journal - April 2020 - 85
ASHRAE Journal - April 2020 - 86
ASHRAE Journal - April 2020 - 87
ASHRAE Journal - April 2020 - 88
ASHRAE Journal - April 2020 - 89
ASHRAE Journal - April 2020 - 90
ASHRAE Journal - April 2020 - 91
ASHRAE Journal - April 2020 - 92
ASHRAE Journal - April 2020 - 93
ASHRAE Journal - April 2020 - 94
ASHRAE Journal - April 2020 - 95
ASHRAE Journal - April 2020 - 96
ASHRAE Journal - April 2020 - Cover3
ASHRAE Journal - April 2020 - Cover4
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_MCDEBX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WNYSQY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XATVOD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FJSHSS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CCBZDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XDEFVG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VHGNBL
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WPKBNJ
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_UUVCDE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTGDEW
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2023
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LKRFXS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AZSOFG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ERCDBH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QWDFRV
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JHGVDF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPUYHG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SREIBM
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LRTGLK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OKRFGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TZSERA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LVRUIX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RPTVYZ
https://www.nxtbook.com/nxtbooks/ashrae/mini_pub_catalog
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XIYTGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2022
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RFGDOB
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PABXNU
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_REMKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PICVBT
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AOYTVW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JQOPLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IOYTBC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SGAJJF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IGHYER
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PDRKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XCODFR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QSLFGO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ILKVNM
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2021
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPDJKD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VJKSRY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDHUTC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JPPKRR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDLTTH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CKLLES
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SLDOX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_HJETUK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OLUHGE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ZERDGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QVMNEO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTPOKE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_BBATRE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_STUBMW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TPEMPE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JNMKDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FBTTPA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WQMMNE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TVBRYN
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2020
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_KTUZMA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ABEDGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201910
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201909
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019septmeber_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019september
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201908
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201907
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201906
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201905
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201904
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019april
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201903
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019march
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201902
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201901
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2019
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018december
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018october
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2018
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201810
https://www.nxtbook.com/nxtbooks/ashrae/ashraeinsights_201806
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201805
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201804
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201803
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201712
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201711
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201710
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201709
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201705
https://www.nxtbook.com/nxtbooks/ashrae/ashrae_meetinginsert_201610
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acrexindia
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer
https://www.nxtbook.com/nxtbooks/amca/2014summer2
https://www.nxtbook.com/nxtbooks/amca/2014summer
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acma_2014summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201311
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201309
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acmasupp_2013fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201305
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201303
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2013winter
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201211
https://www.nxtbook.com/nxtbooks/ashrae/achr_expo_mexico2012
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201209
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v3
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201205
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201203
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012winter
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201111_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201109_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2011summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201105
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201103
https://www.nxtbookmedia.com