Characterizing the Performance of Fixed Airflow Series Fan-Powered Terminal Units Using a Mass and Energy Balance Approach (ST-16-025)

A traditional mass and energy balance component approach was used to characterize the performance of fixed airflow series fan powered terminal units for applications in building simulation programs. The approach included developing relevant energy and mass balance equations for the components in a fan powered terminal unit – heating coil, fan/motor combination, and mixer. Fan motors that included permanent split capacitor motors controlled by silicon controlled rectifiers or electronically commutated motors were included in the model development. The paper demonstrates how to incorporate the fan/motor combination performance models for both permanent split capacitor and electronically commutated motors into the mass and energy balance approach. The fan models were developed from performance data that were provided by multiple fan powered terminal unit manufacturers. The fan/motor performance data included a fan airflow range from 250 to 3500 ft³/min (0.118 to 1.65 m³/s) and a motor size range from one-third to one hp (248.6 to 745.7 W).