Performance of ECM Controlled VAV Fan Powered Terminal Units
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Date
2009-05-15
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Abstract
Empirical performance models of fan airflow, primary airflow and power consumption were
developed for series and parallel variable air volume fan powered terminal units. An
experimental setup and test procedure were created to test the terminal units at typical design
pressures and airflows. Each terminal unit observed in this study used an 8 in (20.3 cm) primary
air inlet. Two fan motor control methods were considered. The primary control of interest was
the electronically commutated motor (ECM) controller. Data collected were compared with
previous research regarding silicon rectified control (SCR) units. Generalized models were
developed for both series and parallel terminal units. Coefficients for performance models were
then compared with comparable SCR controlled units. Non-linear statistical modeling was
performed using SPSS software (2008).
In addition to airflow and power consumption modeling, power quality was also quantified.
Relationships between real power (watts) and apparent power (VA) were presented as well as
harmonic frequencies and total harmonic distortion. Power quality was recorded for each ECM
controlled terminal unit tested. Additional tests were also made to SCR controlled terminal units
used in previous research (Furr 2006).
The airflow and power consumption performance models had an R2 equal to 0.990 or greater for
every terminal unit tested. An air leakage model was employed to account for leakage in the
parallel designed VAV terminal units when the internal fan was turned off. For the leakage
model, both ECM and SCR controlled units achieved an R2 greater than or equal to 0.918.
Description
Keywords
ECM, VAV, FPTU, Fan, Powered, Terminal, Unit