Search

Airflow measurement is essential to efficiently operate air handling units (AHUs) in commercial buildings. Due to the space and cost limitations for physical meters, many virtual airflow meters have been developed for induction motor driven fan systems. On the other hand, electronically commutated motor (ECM) fans have been widely applied in AHUs. However, the applicability of virtual airflow meters to ECM fan systems remains unclear. The purpose of this paper is to develop and validate a virtual airflow meter for ECM fan systems using measured fan head and motor input power and speed. First, a virtual airflow meter model is developed by referring to an ECM fan energy model and the corresponding calibration procedure is established, then the developed model is calibrated using the manufacturer data of a 7,865 m3/h ECM fan, including fan airflow rate, head and motor input power at different motor speeds, and validated in a test AHU with an array of four calibrated ECM fans. The validation result shows that the developed meter can accurately calculate the total AHU airflow rate with the root mean squared error of 660 m3/h and the normalized root mean squared error of 4%. [ABSTRACT FROM AUTHOR]

Motor-driven fan systems in air handling units (AHUs) account for 15.9% of the electricity consumption in commercial buildings. Currently electronically commutated motors (ECMs) have seen increasing applications to replace induction motors for energy savings. While efficiency models for motor-driven fan systems are essential for building energy management, there is no valid efficiency model for ECM fan systems. Therefore, this paper is to develop and validate an efficiency model for ECM fan systems, which can be applied to evaluate the motor input power at given fan airflow rate and head. First, an efficiency model is developed and calibrated using the manufacturer data of a 5.2 kW ECM fan. Innovatively a fan efficiency correction coefficient is introduced to consider the bias of affinity laws and the correlation between motor efficiency and motor shaft power is verified. Then the calibrated efficiency model is validated in an AHU with an array of four calibrated ECM fans. It was found that the proposed fan efficiency correction coefficient can improve the fan efficiency model accuracy by 20% at 20% rated motor speed. Moreover, the validation results show that the developed efficiency model can accurately evaluate the motor input power with an error of 0.096 kW or 1.8%. [ABSTRACT FROM AUTHOR]