Development and calibration of a model for the dynamic simulation of fans with induction motors

Abstract

In this paper a model for the dynamic simulation of fans used in mechanical air supply systems is described. Thanks to this model, the behavior of fans subject to control by variable frequency drives (VFD) can be predicted, which includes power absorbed by the fan and expected ventilation rates. Hence, it can help design energy control systems for buildings. The proposed model was based on the Modelica language and was developed from the dynamic phasor domain representation, because this representation is a trade-off between the basic non transient representation, that is computationally efficient but cannot describe fan dynamics, and the dynamic time domain model, that is the most representative one but computationally very demanding. A comparison among these models showed that, within fan frequency variations typical of ventilation systems in buildings, the phasor domain model is as representative as the more complex dynamic time domain model in terms of prediction of the dynamic behavior, that is neglected by the basic non transient model. Moreover, the new phasor domain model was validated against measured data relative to a fan installed in a subway station in Barcelona. Thanks to this model, energy consumption of dynamically driven fans can be estimated at the simulation stage, at the expense of a reasonable computational effort.Peer ReviewedPostprint (author's final draft

Dynamic modelling of induced draft cooling towers with parallel heat exchangers, pumps and cooling water network

“…Mechanical power, generated by the electric motor of each fan is partly converted to hydraulic work by the cooling tower fan, based on the hydraulic efficiency [25]. In [8], the first two fan affinity laws are shown that relates flow through the fan (F f ), pressure head created (p f ), and power (P f ) to fan speed (n), from one steady-state operating point (point 0) to another one (point 1) as follows:…”

“…The valves are modelled as per (25) in this paper [32]. The actual volume flow (F/ρ w ) is proportional through the valve coefficient C vCV to the product of the valve characteristic f (.…”

Energy and Exergy Analyses of Forced Draft Fan for Marine Steam Propulsion System during Load Change

“…Many fans, as the one analyzed in this study, are driven by induction motors. Likewise, in power plants, fans driven by induction motors are also used for air supply systems of buildings and are responsible for significant power consumption [29]. A detailed CFD analysis of the fan electrical drive was presented by Ding et al [30].…”

HVAC System

“…In one case in which a French railway station building was modeled and its thermal and electrical loads estimated, the validation deviations were below 10% [16]. The same tool was suitable for accurately modeling single components of building equipment, such as a slinky-coil geothermal heat pump system [17] and mechanical air supply systems in subway stations [18]. Once the parameters are calibrated through comparison with real measured performance, the model can be used as the basis for the simulation of system regulation and control alternatives [19].…”