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Fit for frigid envi­ron­ments

Axial fans for cooling units and evap­o­ra­tors

Besides effi­ciency, espe­cially impor­tant require­ments for fans used in evap­o­ra­tors today are service life and rugged­ness as well as compact dimen­sions permit­ting the produc­tion of space-saving evap­o­ra­tion units. More­over, conve­nient service access is impor­tant for activ­i­ties such as cleaning and de-icing the devices. The air throw also plays an impor­tant role in distrib­uting cold air to a cold store’s remotest corners. Fans designed espe­cially to meet such require­ments provide a variety of bene­fits. Not only do they improve ease of use, they also help to protect valu­able chilled goods as well as contributing to reduced energy costs. In this respect, designs with Green­Tech EC tech­nology deliver partic­u­larly impres­sive results.


Figure 1: The rugged axial fan series is specially designed for evap­o­rator appli­ca­tions

Axial fans in evap­o­ra­tors have to with­stand diffi­cult condi­tions. Work on the cold side of the cooling circuit is very demanding. Ice forma­tion and removal, which often require crude tools, call for rugged solu­tions that also work reli­ably in harsh condi­tions. While devel­oping the AxiCool series, motor and fan specialist ebm-papst Mulfingen gave special consid­er­a­tion to such require­ments. Thanks to their many prac­tical design details, the new axial fans are ideally adapted to their field of appli­ca­tion, simpli­fying compli­ance with hygiene regu­la­tions (Fig. 2).

Ice forma­tion less worri­some; defrosting cycles opti­mised


Figure 2: AxiCool is a series of compact fans for evap­o­ra­tors, shown here with optional hinge

Unfor­tu­nately it will never be possible to avoid ice forma­tion on heat exchangers and fans completely, but it can be minimised with an atten­dant exten­sion of main­te­nance inter­vals. This wish, expressed by many users, was realised by the devel­opers of the new series with a variety of measures. For example, the wall ring and fan blades are made of rugged plastic, a mate­rial for which ice forma­tion is less of a worry than it is for metal-based designs to begin with. By contrast, the fans’ safety grilles are still made of metal. The reason is clear enough when one considers that in prac­tice, ice is also removed from the grille by mechan­ical means. In addi­tion, the metal safety grille is not curved, making cleaning easier. This hybrid design makes the overall system robust and specially designed for this appli­ca­tion.


Figure 3: The heating tape can be inserted into the remov­able ring after instal­la­tion; it prevents unnec­es­sary heat transfer into the cold store.

The wall ring’s two-part construc­tion is a further prac­tical design detail that coun­ter­acts ice forma­tion and opti­mises defrosting cycles by making it possible to retrofit a heating tape when needed. Installing the heating tape directly in the wall ring has the benefit of avoiding unnec­es­sary heat transfer into the cold store because the hollow space acts as insu­la­tion (Fig. 3). Heat orig­i­nates where it is needed, reli­ably preventing ice forma­tion between the fan blades and the wall ring where it could block the fan.

Melt water, hygiene and cleaning


Figure 4: Inte­grated drainage chan­nels reduce water accu­mu­la­tion in the wall ring, decreasing the danger of impeller freeze-up

Drainage chan­nels on the inside of the wall ring ensure that melt water, such as that formed during regular de-icing, can drain in the direc­tion of the drip pan that is normally installed on the evap­o­rator (Fig. 4). This also keeps the fan blades from freezing up when cooling is resumed and averts the danger of water being sprayed into the cold store when the fan restarts. This feature gains in signif­i­cance as hygiene require­ments become more strin­gent. For example, cont­a­m­i­na­tion by splash water must be prevented for food­stuffs in open storage.


Figure 5: The fan can be swung open for easy cleaning of the evap­o­rator unit

Conve­nient cleaning also plays an impor­tant role, espe­cially in connec­tion with hygiene require­ments, and the fans’ surface design allows for this. Flat, smooth surfaces keep the rate of cont­a­m­i­na­tion build-up low to begin with. The motor is protected from splash water for addi­tional protec­tion during cleaning with a water jet. Fan designs with a swivel joint in the inte­grated mounting flange also simplify required servicing such as cleaning the heat exchanger. The tech­ni­cian simply loosens the attach­ment screws and can then swing the fan to the side (Fig. 5).

Air-guiding system for increased air throw


Figure 6: The air throw can be nearly doubled with the optional air-guiding system

Fans used in cold stores face further require­ments. For instance, the distri­b­u­tion of cold air needs to be as uniform as possible, so their air throw becomes a key crite­rion. The AxiCool series thus includes an optional air-guiding system (Fig. 6) that nearly doubles the fan’s air throw while increasing the flow resis­tance only mini­mally so that the air volume and with it the refrig­er­a­tion capacity stay nearly constant (Figs. 7a, 7b). It can be said to “replace” the safety grille; it is easily installed and can also be retro­fitted without diffi­culty at any time. Problem-free removal facil­i­tates easy cleaning, e.g. with a dish­washer.

The axial fans in the AxiCool series are avail­able in sizes of 300, 350 and 450 mm. With their air perfor­mance ranging from 800 to 6,200 m³/h, they are suited to a wide variety of typical evap­o­rator appli­ca­tions (Fig. 8).


Figure 7a (left): Air distri­b­u­tion without air-guiding system; Figure 7b (right): Optimum air distri­b­u­tion with air-guiding system

Both direc­tions of air flow are possible for the designs with safety grilles. The AxiCool series is avail­able for oper­ating temper­a­tures to -40 °C; its external-rotor design allows for very compact dimen­sions. The complete evap­o­rator unit thus requires little space. The fans already exceed the 2015 ErP require­ments today and are avail­able in iden­tical dimen­sions with both AC and energy-effi­cient Green­Tech EC motors.

Designs with EC motors for espe­cially high effi­ciency


Figure 8: AxiCool air perfor­mance range

EC motors produce less waste heat than AC motors because of their signif­i­cantly higher effi­ciency – a major advan­tage for refrig­er­a­tion appli­ca­tions. At the same time, their energy consump­tion is lower. For example, for a size 350 fan it is 25% lower than for the same design with an AC motor. That pays off in prac­tice: at an air volume of 2,500 m³/h the EC fan consumes 42 W less than the AC version. In addi­tion to the direct energy savings resulting from the fan’s reduced power consump­tion, the waste heat it trans­fers into the cold store also needs to be consid­ered. The refrig­er­a­tion process has to use elec­trical power to remove this waste heat. All told, in the overall refrig­er­a­tion process savings of approx­i­mately 55 W can be achieved with the EC fan. Given an elec­tricity price of 0.13 euro/kWh and a working time of 6,000 h/year, the savings per fan add up to 43 euros per year.

As an addi­tional advan­tage, the user can choose between a two-step motor design or a demand-based control system using a 0-10 V signal that simpli­fies customised adap­ta­tions for special refrig­er­a­tion require­ments. Typical example appli­ca­tions include maturing processes for cheese storage, or the storage of sensi­tive fruits and vegeta­bles. In addi­tion, the aeroa­cousti­cally opti­mised design of the fans with HyBlade® plastic impellers allows for noise reduc­tion of up to 4 dB(A) in compar­ison with typi­cally avail­able solu­tions using sheet metal blades. As a compact, effi­cient plug-and-play solu­tion perfectly tailored to its appli­ca­tion, the AxiCool series has a wide variety of uses.

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Additional product information can be found here:

Axial fan AxiCool

AxiCool fans for evaporators and cooling units