EVALUATION OF FAN MODELS FOR APPLICATION TO ECM FAN/MOTOR COMBINATIONS
Electronically commutated motors are applied to drive
the fans in fan powered terminal units for variable
airflow applications. Two fan models used to
characterize larger commercial variable speed fans
were evaluated to determine if they could be applied
to model electronically commutated fan/motor
combinations used in fan powered terminal units.
These models included those by Clark (1985) and
Stein and Hydeman (2004). Four manufacturers
provided detailed performance data on 36 fan/motor
combinations that were used in commercially
available series and parallel fan powered terminal
units. All of the fan motors were electronically
commutated motors with motor sizes ranging from
0.33 to 1 hp (249 to 746 W). The data included
airflow, power, and power factors that were measured
over a range of static discharge pressure from 0.1 to
0.75 in w.g. (25 to 187 Pa).
Both fan models correlated performance data of
individual fan/motor combinations. However, neither
model was able to provide a generalized method to
satisfactorily correlate the wide range of provided by
the manufacturers. In addition, the performance data
for some of the smaller fan/motor combinations
showed considerable variation at lower controller
settings than the data at higher controller settings. A
new model was developed that provided a better
correlation for the fan/motor performance data. This
model could be used by building simulation model
developers seeking a generalized model of ECM
fan/motors used in fan powered terminal units.
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