Performance data were to be collected that could be used to compliment, or contradict, the laboratory results that had been collected under this study and others, for FPTU fan pressure rise.
The static pressure taps were installed in perpendicular holes drilled into the side of the FPTU and the downstream duct.
This means that building simulation programs such as EnergyPlus need to capture the performance of variable airflow FPTUs
. Complete modeling of ECM FPTUs
includes both capturing the part-load performance of the ECMs as well as providing the user with the option to explore how sizing of the ECM FPTU
affects annual energy performance.
Permanent-split capacitor (PSC) motors controlled by silicon controlled rectifiers (SCRs) and electronically commutated motors (ECMs) have been used to drive the fans in parallel FPTUs
. PSC motors are only used in those applications where the airflow from the FPTU
fan is expected to be constant.
This air does not reach the conditioned zone and the primary fan must work harder to provide an extra amount of primary air to the FPTU
to offset the loss through the backdraft damper.
Figure 1 shows a simple series FPTU
. Primary air from the central cooling coil and air handler enters on the right in Figure 1.
The airflow in the parallel fans was set at the heating airflow rate unlike the series FPTU
fan, which was set at the cooling airflow rate, generally higher than the heating rate.
Mass and energy streams enter and exit a series FPTU
through several paths.
Therefore, the ultimate goal of the research reported in this paper is to develop a variable-airflow parallel FPTU
model that can be implemented in building energy simulation programs, such as EnergyPlus, with the capability of capturing the energy impact of air leakages.
Manufacturers used permanent split capacitor (PSC) motors with silicon-controlled rectifiers (SCRs) and electronically commutated motors (ECMs) to drive the fans in FPTUs
. PSC motors are applied in situations where the airflow provided by the FPTU
fan is fixed.
Considering the limitations in EnergyPlus for modeling FPTUs
, there was a need to develop new FPTU
models that were compatible with the MEB modeling approach used in EnergyPlus yet also capable of providing realistic performance representations of FPTUs
in both fixed- and variable-airflow operations.
An example is an online reference showing an example EnergyPlus input file with a series FPTU
fan pressure rise of 1000 Pa (4.0 in.w.g.) (Big Ladder 2017).