This study develops a method to estimate the energy performance of blowers that are driven by electronically commutated motors (ECM) in residential gas furnaces based on the measurement of blower rotational speeds. As the first step, the airflow and power of six different ECM blowers from four manufacturers were measured over a range of external static pressures (ESPs) from 0.1 to 1.2 in. w.g. (25 to 300 Pa) in a well-instrumented laboratory environment with a calibrated nozzle airflow chamber. Then, the ECM blower energy performance was determined from the airflow and power measurements and characterized in terms of efficacy, which is the ratio of blower power to airflow rate. In addition, the relationship between parameters of blower rotational speed and efficacy was investigated, leading to the linear correlation development for each tested blower by taking the blower rotational speed as the independent variable and the efficacy as the dependent variable.
Results from the linear correlation development show that ECM blower efficacies can be accurately predicted by using blower rotational speeds as evidenced by the high R2 values ranging from 0.961 to 0.981. For the six tested ECM blowers, the linear factor for the developed correlations varies from -2.881 to -2.657, and the offset factor is in a range of 3.287 to 3.551. Furthermore, a comparison between the predicted and measured efficacies shows an accuracy of ±15% for the developed correlations.
Results generated from this study provide a method to predict the energy performance in terms of efficacies for ECM blowers based on the knowledge of rotational speed. In addition, the experimental data and correlations produced in this study can be used to model the ECM blower efficacy behaviors at different operating speeds.
