Fans func­tion effi­ciently when their optimal oper­ating range is harmo­nized with the application’s require­ments. Fans in evap­o­ra­tors must over­come high counter-pres­sure since the ice that often forms on the heat exchanger constricts the air chan­nels. From that point of depar­ture, motor and fan specialist ebm-papst devel­oped AxiEco Protect (Fig. 1), a new axial fan series in both EC and AC tech­nology. It features high effi­ciency and unusu­ally high stability under pres­sure.

AxiEco Protect’s air perfor­mance curve has a much steeper slope than that of compa­rable axial fans (Fig. 2). In prac­tical use, this results in several bene­fits. Even when the counter-pres­sure is high, the fans func­tion at high effi­ciency. As a result, even AC designs satisfy the require­ments of the future ErP Direc­tive. Manu­fac­turers can now choose the tech­nology upon which they prefer to rely. And service life, the interval between defrost cycles, is also extended. This also saves energy and increases the device’s overall effi­ciency.

Figure 1: The new AxiEco Protect in EC tech­nology (left) and AC tech­nology (right). (Photo | ebm-papst)

New aero­dy­namics concept

The key to the increased effi­ciency and higher pres­sure increase of AxiEco Protect fans is aero­dy­namic opti­miza­tion. For example, the impeller, inte­grated diffusor ring, and hub form a compact unit and the blade tips seam­lessly join the inte­grated diffusor ring. This elim­i­nates the head gap between nozzle and impeller, also elim­i­nating the blade tip over­top­ping seen in conven­tional axial fans. The new design increases effi­ciency and reduces noise at the same time.

The inte­grated diffusor ring also func­tions as a diffuser that is directly inte­grated into the impeller. It increases the pres­sure, resulting in reduced exit loss and less noise. Thanks to the inlet ring that immerses in the impeller and a larger outlet opening, the fan has an optimal flow (Fig. 3).

Figure 2: The air perfor­mance curve of the AxiEco Protect has a much steeper slope than that of the HyBlade while main­taining the high effi­ciency level. (Chart | ebm-papst)

Perfectly harmo­nized to different appli­ca­tions

With many prac­tical design details, the new AxiEco Protect has been opti­mized for venti­lation, refrig­er­a­tion and air condi­tioning appli­ca­tions. When used in evap­o­ra­tors or heat pumps, the axial fan series makes both service work and compli­ance with hygiene rules easier. It will never be possible to fully prevent ice forma­tion on heat exchangers and fans. But it is possible to mini­mize it, which also extends their service life.

Many users have wished for reduced ice forma­tion, and the devel­opers fulfilled their wish in the new series by applying several measures. The new flow profile of AxiEco Protect fans ensures that guard grills do not ice as quickly. And the impeller with the inte­grated diffusor ring has been produced in highly resis­tant plastic, a mate­rial that, in and of itself, discour­ages icing. The fans’ guard grill is made of metal, which means that it is highly robust. The reason for this is that mechan­ical means are usually employed to remove the ice forming on the grill.

Figure 3: Thanks to its optimal flow condi­tions, AxiEco Protect continues to func­tion effi­ciently even when counter-pres­sure increases. (Illus­tra­tion | ebm-papst)

Drainage chan­nels on the fan blades ensure that after routine defrosting, melt water can easily drain towards the drip pan provided at the evap­o­rator. They prevent the fan blades from freezing up. At the same time, water is prevented from splashing when the fan is restarted. The more strin­gent the hygiene require­ments, the more impor­tant this feature becomes. Splash water must be prevented from cont­a­m­i­nating food stored in open containers when­ever possible, for example.

The fans come in sizes 300, 350, 400, 450, and 500 and are avail­able in EC and AC design (Fig. 4). With air flows of up to 12,000 m³/h and pres­sures of up to 450 Pa, they are ideal for a number of typical appli­ca­tions in refrig­er­a­tion, air condi­tioning and venti­lation tech­nology, and can be used for both pres­sure and suction. As a compact plug & play solu­tion, they are easily inte­grated into appli­ca­tions. In the easiest cases, they can be placed on an existing short nozzle.

Figure 4: Air perfor­mance curves of the new AxiEco Protect axial fans in EC tech­nology. (Chart | ebm-papst)

The new AxiEco Protect fans satisfy the require­ments of the next ErP stage, regard­less of the motor tech­nology used. And the fans with EC motors offer many more advan­tages. In compar­ison to AC motors, EC motors func­tion with consid­er­ably higher effi­ciency. They also generate less waste heat, an impor­tant advan­tage for chilling appli­ca­tions. Needs-based controls and fan moni­toring via 0-10 V signal or MODBUS are also possible.

These features help the EC fans to work very effi­ciently in the partial-load range as well, and signif­i­cantly reduce energy consump­tion. This facil­i­tates indi­vidual adap­ta­tion to partic­ular cooling require­ments. Typical exam­ples include the maturing of cheese and the ripening of sensi­tive fruit and vegeta­bles in storage, and varying day and night oper­a­tion. The new features enable needs-based air flow to be easily set in venti­lation appli­ca­tions as well. As of fall 2020, an advanced devel­op­ment will allow the robust fans to be used in mechan­ical engi­neering along­side addi­tional refrig­er­a­tion, venti­lation and air condi­tioning appli­ca­tions.