ASHRAE Journal - June 2019 - 28

TECHNICAL FEATURE

FIGURE 5 Contours of normalized air velocity at the central plane with the heat source on the table show that weak discharge jet under low supply airflow rates cannot sustain
the downward unidirectional motion and spreads sideward right after the discharge.

a) 200 cfm (94.4 L/s)

600 cfm (283.2 L/s)

d) 800 cfm (377.6 L/s)

Non-Isothermal Analysis-Heat Source Near The Ceiling
These analyses were performed by placing the heat
sources near the ceiling surrounding the supply diffuser
for four different supply airflow rates. Results for these
analyses are presented in Figures 7, 8, and 9 showing the
airflow patterns, velocity, and temperature distribution,
respectively at the central plane. Such configuration
can set circulating airflow patterns that can promote
entrainment of the surrounding air and acceleration of
the cold supply jet.
These analyses also show two significantly different
flow patterns: one for the supply airflow rates of 200
cfm (94.4 L/s) and the other for the supply airflow rates
above 200 cfm (94.4 L/s). In the case of low supply airflow rate of 200 cfm (94.4 L/s) the low velocity discharge
jet moves sideward instead of downward, distributes the
cold air in the space, and holds hot stratified air near
the ceiling. It should be noted that in this case the zone
28

ASHRAE JOURNAL

ashrae.org

400 cfm (188.8 L/s)

J U N E 2 0 19

of high velocity remains attached to the ceiling (Figure
8a). This results in a uniform temperature distribution
in the space with the highest temperature gradient near
the ceiling between the cold supply jet and the surrounding hot air (Figure 9a).
Whereas in the other cases of high supply flow rates
above 200 cfm (94.4 L/s), increase in the discharge
velocity forms unidirectional air jets and the cold air
starts moving downward towards the table. Like in the
previous analysis, in this case when the cooling capacity
of the supply air becomes four times the sensible heat
load, the zone of high velocity moves downward and the
cold air reaches the top surface of the table (Figures 8 and
9). All these cases show significant thermal stratification
with hot air near the ceiling; however, with increasing
cooling capacity of the supply air, the thermal gradients between the cold air jet and the surrounding air
decrease (Figure 9).


https://www.ashrae.org/

ASHRAE Journal - June 2019

Table of Contents for the Digital Edition of ASHRAE Journal - June 2019

Contents
ASHRAE Journal - June 2019 - Intro
ASHRAE Journal - June 2019 - Cover1
ASHRAE Journal - June 2019 - Cover2
ASHRAE Journal - June 2019 - 1
ASHRAE Journal - June 2019 - Contents
ASHRAE Journal - June 2019 - 3
ASHRAE Journal - June 2019 - 4
ASHRAE Journal - June 2019 - 5
ASHRAE Journal - June 2019 - 6
ASHRAE Journal - June 2019 - 7
ASHRAE Journal - June 2019 - 8
ASHRAE Journal - June 2019 - 9
ASHRAE Journal - June 2019 - 10
ASHRAE Journal - June 2019 - 11
ASHRAE Journal - June 2019 - 12
ASHRAE Journal - June 2019 - 13
ASHRAE Journal - June 2019 - 14
ASHRAE Journal - June 2019 - 15
ASHRAE Journal - June 2019 - 16
ASHRAE Journal - June 2019 - 17
ASHRAE Journal - June 2019 - 18
ASHRAE Journal - June 2019 - 19
ASHRAE Journal - June 2019 - 20
ASHRAE Journal - June 2019 - 21
ASHRAE Journal - June 2019 - 22
ASHRAE Journal - June 2019 - 23
ASHRAE Journal - June 2019 - 24
ASHRAE Journal - June 2019 - 25
ASHRAE Journal - June 2019 - 26
ASHRAE Journal - June 2019 - 27
ASHRAE Journal - June 2019 - 28
ASHRAE Journal - June 2019 - 29
ASHRAE Journal - June 2019 - 30
ASHRAE Journal - June 2019 - 31
ASHRAE Journal - June 2019 - 32
ASHRAE Journal - June 2019 - 33
ASHRAE Journal - June 2019 - 34
ASHRAE Journal - June 2019 - 35
ASHRAE Journal - June 2019 - 36
ASHRAE Journal - June 2019 - 37
ASHRAE Journal - June 2019 - 38
ASHRAE Journal - June 2019 - 39
ASHRAE Journal - June 2019 - 40
ASHRAE Journal - June 2019 - 41
ASHRAE Journal - June 2019 - 42
ASHRAE Journal - June 2019 - 43
ASHRAE Journal - June 2019 - 44
ASHRAE Journal - June 2019 - 45
ASHRAE Journal - June 2019 - 46
ASHRAE Journal - June 2019 - 47
ASHRAE Journal - June 2019 - 48
ASHRAE Journal - June 2019 - 49
ASHRAE Journal - June 2019 - 50
ASHRAE Journal - June 2019 - 51
ASHRAE Journal - June 2019 - 52
ASHRAE Journal - June 2019 - 53
ASHRAE Journal - June 2019 - 54
ASHRAE Journal - June 2019 - 55
ASHRAE Journal - June 2019 - 56
ASHRAE Journal - June 2019 - 57
ASHRAE Journal - June 2019 - 58
ASHRAE Journal - June 2019 - 59
ASHRAE Journal - June 2019 - 60
ASHRAE Journal - June 2019 - 61
ASHRAE Journal - June 2019 - 62
ASHRAE Journal - June 2019 - 63
ASHRAE Journal - June 2019 - 64
ASHRAE Journal - June 2019 - 65
ASHRAE Journal - June 2019 - 66
ASHRAE Journal - June 2019 - 67
ASHRAE Journal - June 2019 - 68
ASHRAE Journal - June 2019 - 69
ASHRAE Journal - June 2019 - 70
ASHRAE Journal - June 2019 - 71
ASHRAE Journal - June 2019 - 72
ASHRAE Journal - June 2019 - 73
ASHRAE Journal - June 2019 - 74
ASHRAE Journal - June 2019 - 75
ASHRAE Journal - June 2019 - 76
ASHRAE Journal - June 2019 - 77
ASHRAE Journal - June 2019 - 78
ASHRAE Journal - June 2019 - 79
ASHRAE Journal - June 2019 - 80
ASHRAE Journal - June 2019 - Cover3
ASHRAE Journal - June 2019 - Cover4
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