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More power, more effi­ciency: air guide modules for centrifugal fans

If the effi­ciency of centrifugal fans is improved by just a few percentage points, the energy consump­tion and the CO2 foot­print are reduced. This is demon­strated by the new RadiPac C Perform fans with air guide modules.

For some time now, motor and fan specialist ebm-papst has been employing a contin­uous improve­ment process in fan tech­nology. In recent years, the centrifugal fans in the RadiPac series, specially designed for use in air condi­tioning and venti­la­tion units, have been constantly opti­mized, with partic­ular emphasis on energy effi­ciency, noise reduc­tion, and easy handling.

Fig. 1: In the RadiPac C Perform centrifugal fan, the four-part air guide module reduces outlet losses, increasing the effi­ciency by up to 5 percentage points. This enabled the proven support bracket to be retained. (Photo | ebm-papst)

With the new RadiPac C Perform fans, we have now succeeded in improving this successful series yet again. Special air-conducting modules now increase the effi­ciency by up to 5 percent, while the proven support brackets have been retained (Fig. 1).

This means that the mounting dimen­sions and mounting hole patterns remain iden­tical, so prac­ti­cally no design changes are neces­sary in the appli­ca­tion to benefit from the higher effi­ciency levels and lower current consump­tion.

Air guide modules increase the effi­ciency

Air guide modules reduce outlet losses in the RadiPac C Perform fans. With free-blowing fans, these are often under­es­ti­mated energy guzzlers, as the impeller drive power Po is divided into the static delivery rate that can be used for the user (Pus = product of air flow and static pres­sure increase of the fan) and the different losses that occur during the conver­sion.

Fig. 2: The design measures delay the flow, which reduces the dynamic pres­sure compo­nent and increases the usable static pres­sure compo­nent. (Graphic | ebm-papst)

Here, the greatest loss factor is the dynamic power compo­nent (Pud) of the air perfor­mance, which is also referred to as the outlet loss. It is made up of the product of the air flow and the dynamic pres­sure. To mini­mize these losses, ebm-papst has devel­oped a housing for the RadiPac, consisting of four segments.

The module segments are made of galva­nized sheet steel and have an aero­dy­namic shape. This special shape slows down the flow speed, which reduces the dynamic pres­sure compo­nent and increases the usable static pres­sure compo­nent (Fig. 2). In addi­tion, the new flange plate was turned 15 degrees and provided with recesses at the flow outlet, which also helps to reduce exit losses. At the same oper­ating point, for example, the fans can run at a lower speed, which in turn means that less energy is required (Fig. 3).

Fig. 3: At the same oper­ating point, size 560 fans can run at a lower speed, which in turn lowers the energy require­ments (char­ac­ter­istic curve A green: RadiPac C Perform compared to char­ac­ter­istic curve B orange: RadiPac C). (Graphic | ebm-papst)

Fan selec­tion made easy thanks to FanScout

Whether users opt for the new RadiPac C Perform fans with air guide modules or the tried-and-tested versions with open support bracket depends on several factors. In both RadiPac designs, highly effi­cient Green­Tech EC motors are used as a drive and the shape of the five-blade impeller meets the latest aero­dy­namic criteria. The effi­ciency of the external rotor motors fulfills the require­ments for effi­ciency class IE5 set in IEC/TS 60034-30-2. For system effi­ciency, the drive system, consisting of motor and inte­grated power elec­tronics, is indi­vid­u­ally adapted on each fan, and is opti­mized for the rele­vant oper­ating range.

FanScout deter­mines the most econom­ical fan solu­tion based on appli­ca­tion-specific oper­ating points and the expected oper­ating times.

Which RadiPac variant ulti­mately pays off more for the user depends primarily on the type of use and dura­tion, the required air perfor­mance, the desired speed range and the pres­sure ratio of the appli­ca­tion. However, the FanScout selec­tion program makes it easy to choose the right one.

Fig. 4: The FanScout selec­tion soft­ware makes it easy to find the right fan. (Photo | ebm-papst)

The selec­tion soft­ware (Fig. 4) iden­ti­fies the most econom­ical fan solu­tion, using up to five appli­ca­tion-specific oper­ating points and the expected oper­ating times. The amount of instal­la­tion space avail­able, maximum number of fans required and redun­dancy require­ments can also be taken into account. To make the eval­u­a­tion of the various options even more useful to the user, FanScout also has a func­tion that iden­ti­fies the life cycle costs of the combi­na­tion under consid­er­a­tion.

This involves multi­plying the power consump­tion of the fans at each oper­ating point by the oper­ating time and elec­tricity costs, and adding up the total. The result repre­sents the pure oper­ating costs of the instal­la­tion over a spec­i­fied period. After you enter the costs for the purchase, instal­la­tion and service, the overall costs over time are displayed. This provides users with a real­istic cost assess­ment and a reli­able basis for their invest­ment deci­sions.

Auto­matic reso­nance detec­tion for more oper­a­tional reli­a­bility

Centrifugal fans are used in a wide range of appli­ca­tions. Depending on the instal­la­tion situ­a­tion, reso­nance can occur in unpre­dictable speed ranges. If the fan is often oper­ated in such crit­ical ranges, the drive motor’s bearing system may be damaged, leading to prema­ture fan failure. Although these vibra­tions can be measured for system oper­a­tors, they cannot simply be elim­i­nated. ebm-papst solves this problem with RadiPac and RadiPac C Perform centrifugal fans using auto­matic reso­nance detec­tion, which avoids oper­a­tion at crit­ical speeds, increasing the service life and oper­a­tional reli­a­bility.

Fig. 5: Vibra­tion behavior with omitted speed range. (Graphic | ebm-papst)

In addi­tion, a test start-up can be performed during commis­sioning in which the vibra­tion speed is analyzed over the entire speed progres­sion from stand­still to nominal speed. If exces­sive vibra­tion speeds are detected in certain areas, the control soft­ware adjusts itself after acti­va­tion by the customer so that these speed ranges are “passed over” in the future. This means that the ranges are passed through, but contin­uous oper­a­tion in them is avoided (Fig. 5). Oper­a­tors can manu­ally edit the soft­ware settings at any time, meaning that they always have full control.

The energy-saving RadiPac C Perform fans with air guide modules in support bracket are currently avail­able in seven sizes (BG 280 to BG 630) and with outputs of up to 8 kW. Versions without air guide modules are avail­able in the same sizes with motor powers from 85 W to 8 kW.

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