ASHRAE Journal Supplement - AMCA InMotion - November 2021 - 6

■
Idealized thermal-plume assumptions had a substantial
impact on results for the FS-0 cases. In the real world,
occupant movement, passing traffi c, and the like disrupt
thermal plumes, making them less effective at transporting
particles emitted by occupants to the upper region of a
space. In other words, the FS-0 cases may underestimate
particle concentrations in the region near occupants.
L-V-S-6
10
15
20
25
5
10
15
20
25
5
10
15
20
25
5
10
15
20
25
5
FS-3
FS-0.6
FS-0
10
15
20
25
5
working zone breathing zone
L-H-S-6
FS-3
FS-0.6
FS-0
10
15
20
25
working zone breathing zone
M-V-S-6
FS-3
FS-0.6
FS-0
5
10
15
20
25
working zone breathing zone
U-H-S-6
FS-3
FS-0.6
FS-0
5
10
15
20
25
working zone breathing zone
FS-3
FS-0.6
FS-0
2
4
6
8
0 0
100
5
L-V-S-3
FS-3
FS-0.6
FS-0
10
15
20
25
working zone breathing zone
L-H-S-3
FS-3
FS-0.6
FS-0
10
15
20
25
working zone breathing zone
M-V-S-3
FS-3
FS-3_reverse
FS-0.6
FS-0.6_reverse
FS-0
working zone breathing zone
U-H-S-3
FS-3
FS-0.6
FS-0
10
15
20
25
working zone breathing zone
FS-3_noheat
FS-0.6_reverese
FS-0_no heat
U-H-D-3
FS-3_reverse
FS-0.6_noheat
5
(a)
10
15
20
5
working zone
(c)
200
Time, min
(b)
300
400
500
Notes:
* Best case: FS-3 (green line) = full speed (3 m/s [10 fps]) in
downward direction
* Worst case: FS-0.6 (black dotted line) = 20-percent speed (0.6
m/s [2 fps]) in upward direction
FIGURE 4. (a) Working-zone and whole-warehouse-breathing-zone concentrations at the end of eight hours;
(b) transient concentrations; (c) concentrations at the eighth hour for U-H-D-3. " Noheat " indicates a simulation
with thermal-buoyancy-driven fl ow disabled, while " reverse " indicates fan direction was reversed.
6
2021 AMCA inmot ion
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breathing zone
U-H-D-3
FS-3
FS-3_noheat
FS-0.6_reverse
FS-0
FS-3_reverse
FS-0.6
FS-0.6_noheat
FS-0_noheat
5
10
15
20
25
5
5
■
Both dilution and deposition were the major mechanisms
by which high fan speeds reduced particle concentrations
near occupants.
Figure 4a shows breathing-zone and working-zone
concentrations for a variety of fan speeds and scenarios,
with fi gures 4b and 4c focusing on U-H-D-3.
To better understand the impact of fan speed, the
L-V-D-6
FS-3
FS-3_racks
FS-0.6
FS-0.6_racks
FS-0
FS-0_racks
working zone breathing zone
L-H-D-6
FS-3
FS-0.6
FS-0
10
15
20
25
working zone breathing zone
M-V-D-6
FS-3
FS-0.6
FS-0
5
10
15
20
25
working zone breathing zone
U-H-D-6
FS-3
FS-0.6
FS-0
5
10
15
20
25
working zone breathing zone
5
10
15
20
25
5
L-V-D-3
FS-3
FS-0.6
FS-0
working zone breathing zone
L-H-D-3
FS-3
FS-0.6
FS-0
working zone breathing zone
M-V-D-3
FS-3
FS-0.6
FS-0
working zone breathing zone
U-H-D-3
FS-3
FS-3_noheat
FS-3_reverse
FS-0.6
FS-0.6_reverse FS-0.6_noheat
FS-0
FS-0_noheat
working zone breathing zone
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ASHRAE Journal Supplement - AMCA InMotion - November 2021

Table of Contents for the Digital Edition of ASHRAE Journal Supplement - AMCA InMotion - November 2021
