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Modeling of Electronically Commutated Motor Controlled Fan-powered Terminal UnitsEdmondson, Jacob Lee 2009 December 1900 (has links)
Empirical models of airflow and power consumption were developed for series
and parallel variable air volume fan powered terminal units (FPTUs). An experimental
setup and test procedure were developed to test the terminal units over typical operating
ranges. The terminal units in this study used either an 8 in. (20.32 cm) or a 12 in. (30.48
cm) primary air inlet. All terminal units utilized electronically commutated motor
(ECM) controllers. Data collected were compared against previous data collected for
silicon controlled rectifier (SCR) units. Generalized models were developed for both
series and parallel units, and compared against models developed for SCR units.
In addition to the performance modeling, power factor and power quality data
were also collected for each terminal unit. The power quality analysis included
recording and analyzing harmonic distortion for current, voltage, and power up to the
25th harmonic. The total harmonic distortion (THD) was also recorded and presented.
For the series terminal units, models were developed for fan airflow, fan power,
and primary airflow. The models for fan airflow all had R2 values above 0.987. The models for fan power all had R2 values above 0.968. The models for primary airflow all
had R2 values above 0.895.
For the parallel terminal units, models were developed for leakage, fan airflow,
fan power, and primary airflow. All of the leakage models had R2 values above 0.826.
All of the fan airflow models had R2 values above 0.955. All of the fan power models
had R2 values above 0.922. All of the primary airflow models had R2 values above
0.872.
The real power THD was below 1.5 percent for both series and parallel FPTUs. The
current THD ranged from 84 percent to 172 percent for series FPTUs and from 83 percent to 183 percent for
parallel FPTUs. The voltage THD was below 1.4 percent for both series and parallel FPTUs.
The performance models developed will help improve the accuracy of building
energy simulation programs for heating, ventilation, and air conditioning (HVAC)
systems utilizing ECM controlled FPTUs. Increasing the accuracy of these simulations
will allow HVAC system designers to better optimize their designs for specific building
types in a wide variety of climates.
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Modeling of ECM Controlled Series Fan-powered VAV Terminal UnitsYin, Peng 2010 August 1900 (has links)
Semi-empirical models for series fan-powered variable air volume terminal units
(FPTUs) were developed based on models of the primary, plenum, fan airflow and the
fan power consumption. The experimental setups and test procedures were developed
respectively for primary, plenum and fan airflow to test each component of the FPTUs at
typical design pressures and airflows. Two sizes of the terminal units from three
manufacturers were used in this study. All of the FPTUs were equipped with
electronically commutated motors (ECM). Data provided by the models were compared
against the data from previous experiments to prove the models’ validity. Regression
modeling was performed by using SigmaStat.
The model of primary airflow had an R2 above 0.948 for all the terminal units
evaluated while the plenum airflow model had an R2 above 0.99. For all the terminal
units, the R2 of the fan airflow model was ranged from 0.973 to 0.998. Except for one fan, the fan power consumption model was able to characterize the power performance
and had an R2 above 0.986.
By combining the airflow and power models, the model for series FPTU was
developed. Verification was made to prove the FPTU model’s validity by comparing the
measured and predicted data of airflow and power consumption. Correction factors were
used in the primary airflow model to compensate for the difference caused by large
measurement errors and the system effects. The predicted values were consistent with
measurements and no offset was needed in the primary airflow model. Generally, the
newly established model was able to describe the airflow performance as well as power
consumption of series FPTUs without adding complexity.
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