The easy way to replace “old” with “highly effi­cient”

Compact fan dimen­sions are highly desir­able for all venti­lation and air condi­tioning appli­ca­tions. After all, instal­la­tion space always tends to be at a premium. Energy effi­ciency is also an impor­tant aspect, not least because of the need to meet the minimum require­ments set down by the Ecode­sign regu­la­tion, which came into force for fans in 2015. Modern fans featuring energy-saving EC tech­nology have plenty to offer in this respect: The compact fans do not just satisfy currently applic­able and future require­ments, they already clearly surpass them. This is of equal benefit to both the envi­ron­ment and customers, partic­u­larly as new concepts make retro­fitting a simple matter for air condi­tioning unit manu­fac­turers without the need for any design modi­fi­ca­tions.

Figure 2: The double-flow centrifugal fan product range in a scroll housing with back­ward-curved blades, shown here with mounting bracket in 90° posi­tion.

At present, the fans of venti­lation and air condi­tioning units are often powered by asyn­chro­nous motors which drive the impeller by way of a belt. Such an arrange­ment takes up a lot of space inside the air condi­tioning device and makes instal­la­tion compli­cated. The number of wearing parts also creates addi­tional service work in the course of oper­a­tion. What’s more, this widely used concept is not ideal in terms of hygiene, as belt abra­sion can have a detri­mental effect on the air quality. Another draw­back to this constel­la­tion is that it is diffi­cult to satisfy the demands for optimum util­i­sa­tion of the primary energy supplied. In addi­tion, the effi­ciency of asyn­chro­nous drives leaves some­thing to be desired, with a level of between 20% and 70% depending on the shaft power. Speed control – for demand-based power adjust­ment or noise reduc­tion for example – can only be imple­mented with the use of addi­tional compo­nents such as frequency converters.

Direct-drive EC fans

Given these factors, direct-drive EC fans are an excel­lent alter­na­tive. EC motors exhibit the same char­ac­ter­is­tics as DC motors, can be just as easily regu­lated and attain effi­ciency levels of up to 90%. As well as making better use of the primary energy, another advan­tage is a reduc­tion in heat loss during oper­a­tion which has a posi­tive effect on the service life of the ball bear­ings employed. A further argu­ment in favour of using EC fans in venti­lation and air condi­tioning devices is their compact external rotor design. The elec­tron­i­cally commu­tated motor is inte­grated directly into the impeller, thus signif­i­cantly reducing the instal­la­tion dimen­sions (Figure 1). There is no need for a belt drive between motor and fan or a frequency converter. Thanks to EC tech­nology, new air condi­tioning devices are more compact and so require less space at the instal­la­tion loca­tion. It is however possible to put the energy-saving tech­nology to good use in existing designs as well. Retro­fitting, in other words replacing “old” with “energy-effi­cient”, is now no problem, as ebm-papst proves with the new RadiFit product range (Figure 2).

Energy-saving tech­nology in the scroll housing

Figure 3: Air perfor­mance levels of up to 10,000 m³/h are possible depending on the size.

The double-flow centrifugal fan product range with back­ward-curved blades in the scroll housing was designed as an energy-saving system concept for any number of appli­ca­tions in industry and venti­lation tech­nology. Depending on the size, this is suit­able for air perfor­mance levels of up to 10,000 m³/h (Figure 3). Thanks to the high-perfor­mance Green­Tech EC drives, these centrifugal fans operate with a high degree of effi­ciency in combi­na­tion with a high static pres­sure. The aero­dy­nam­i­cally opti­mised blade channel of the high-perfor­mance impeller and the ideally adapted scroll housing play an impor­tant part in this respect. The overall effect is a reduc­tion in energy consump­tion. Prac­tical tests have proven that savings of more than 40% are possible as compared to a conven­tional cylin­drical rotor AC fan with the same air perfor­mance. The fans are also extremely quiet-running thanks to the low-noise commu­ta­tion and dynamic balancing of the impeller rotor unit. The gener­a­tion of struc­ture-borne noise is minimised, thus reducing the load on the bear­ings and so helping to extend the service life.

Figure 4: Typical appli­ca­tions include low-profile air condi­tioning devices (a) …

These char­ac­ter­is­tics offer advan­tages in a wide range of appli­ca­tions, for example in so-called low-profile air condi­tioning devices (Figure 4a) which use the heat of the exhaust air to warm the intake air. To do so, the fans convey the air through the heat exchanger and then through the intake and exhaust air ducts. Compact, energy-effi­cient EC fans with speed control are ideal for this purpose, partic­u­larly in view of the strin­gent energy conser­va­tion regu­la­tions applic­able in this field. This simi­larly applies to central air handling units (Figure 4b), where the fans have to convey the air through filters, heat exchangers or humid­i­fiers and dehu­mid­i­fiers as well as branched duct systems whilst providing compen­sa­tion for any loss of pres­sure. At the same time, the system must be as space-saving as possible and ensure simple, demand-based venti­lation for a large number of rooms. Fans do however also have to satisfy similar require­ments in indus­trial appli­ca­tions, for gener­ator cooling for instance (Figure 4c). In this case the fan forces the ambient air through narrow ducts at the gener­ator – which is where the new centrifugal fans really come into their own: Thanks to the inte­grated speed control, cooling can be constantly adapted to suit load and heat gener­a­tion. And as it does not require sepa­rate actu­a­tion the fan needs little instal­la­tion space.

Modular concept with flex­ible connec­tion options

Figure 5: The elec­tronics with connec­tion area can be fitted on the right or left of the housing; the user can then turn the connec­tion area itself to the desired posi­tion or the cable exit can be fitted facing down­wards.

EC centrifugal fans are designed for prac­tical instal­la­tion and can easily be adapted to different situ­a­tions. Vari­able foot posi­tions are possible for the size range 250 to 400 and the fans can also be supplied without a flange. Sizes 310, 355 and 400 are avail­able in the successful cube design. The emphasis was also placed on flex­i­bility with regard to elec­trical connec­tion. For example the elec­tronics with connec­tion area (Figure 5) can be fitted on the right or left of the housing; the user can then turn the connec­tion area itself to the desired posi­tion. The fans are supplied as a complete unit in a housing and wired ready for connec­tion, thus providing customers with a prac­tical Plug & Play package for their air condi­tioning appli­ca­tions. Being designed for different power supplies and oper­a­tion in 50 Hz and 60 Hz systems, the fans are suit­able for use throughout the world. With the RadiFit product range, an energy-effi­cient, prac­tical retrofit concept for air condi­tioning devices is now avail­able with imme­diate effect.