MegaFan HVLS Fan Case Study
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Domain Geometry
• 30m x 30m
warehouse domain
• 7.3m MaxAir HVLS
fan
• Fan at ~36 RPM
• 7°blade pitch
• Ambirad USDA 100
heater, max power 97
kW
• Heater output ~9,000
m3/h
V i d
Varying
domain
i h
height
i ht
Blade Aerodynamics
• Required for fan downwash model
• 2D CFD analysis performed at many angles
of attack
• Computational mesh of ~300,000 cells
Blade Aerodynamics
• Contours
C t
off pressure att α = 8°
Blade Aerodynamics
• Contours
C t
off velocity
l it magnitude
it d att α = 8°
Blade Aerodynamics
CL
NACA0012
CD
CM
Megafan
blade
Model Execution
• Test cases:
- 12.5m, 15m, 17.5m & 20m @ 4oC
- 17.5m @ 0oC
- 17.5m @ -4oC
• Each
E h ttestt case requiring
i i ~8
8 runs
- Fan on, various heater powers
- Fan off, various heater powers
6 cases
x 8 runs
x 2 days per run
96 days of run-time
run time
= ~96
Model Results
Temperature contours
Fan on (14.6 kW)
15 m
12
2.5 m
Fan off (29.1kW)
• Stratification clear in ‘fan off’ cases
• With ‘fan
fan on’
on , warehouse is totally de-stratified
de stratified
Temperature (oC)
Model Results
Temperature contours
Fan on (14.6 kW)
20 m
17
7.5 m
Fan off (29.1kW)
• Stratification clear in ‘fan off’ cases
• With ‘fan
fan on’
on , warehouse is totally de-stratified
de stratified
Temperature (oC)
Model Results
Velocity contours
Fan on (14.6 kW)
15 m
12
2.5 m
Fan off (29.1kW)
• Fan off – mixing only comes from heater
• Fan on – downwash and wall jet clearly evident
Velocity Magnitude (m/s)
Model Results
Velocity contours
Fan on (14.6 kW)
20 m
17
7.5 m
Fan off (29.1kW)
• Fan off – mixing only comes from heater
• Fan on – downwash and wall jet clearly evident
Velocity Magnitude (m/s)
Model Results
Flow Streamlines
Velocity Magnitude (m/s)
Energy Saving Calculations
• Determine mean
temperature
p
at z = 1.5m
for each of the runs
• Fit curve of the form:
y = AxB + C
• Where curves
intersect T = 16oC gives
estimate of required
power
Model Results
Predicted Energy Savings
• Significant savings at heights above 15m
• Power required to heat warehouse increases as
outside
t id ttemperature
t
falls
f ll
Model Results
Predicted Energy Savings
• Both absolute power savings and percentage
energy savings appear to plateau at 15m apex height
• Although percentage energy savings increase
slightly as outside temperature falls, absolute
savings
i
are still
till significant
i ifi
t
Model Results
Predicted Energy Savings
• Fan on and off curves diverge as outside
temperature falls
• Indicates
I di t iincrease iin savings
i
with
ith reducing
d i outside
t id
temperatures
MegaFan HVLS Fan Case Study
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