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Plug & play axial fans for appli­ca­tions with high back pres­sure

Axial fans are normally used for situ­a­tions when strong air flow with rela­tively low back pres­sure is required. That is why they have not yet been the fan of choice for devices that require a high pres­sure increase. But now that has all changed: ebm-papst’s new axial fans are also suit­able for appli­ca­tions with high back pres­sure, meaning that these types of appli­ca­tions can also benefit from their higher air flow rates.

At the start of 2020, ebm-papst intro­duced its AxiEco Protect axial fans with guard grills, which are able to over­come high back pres­sure. The fan and motor specialist is now going a step further by expanding its existing AxiEco series with the AxiEco Perform (Fig. 1) axial fans. These achieve even greater effi­ciency and pres­sure stability and come with an easy-to-install housing made of composite mate­rial.

Fig. 1: Extract from the product range: new AxiEco Perform EC axial fan in size 350 with housing made of composite mate­rial. (Photo | ebm-papst)

The air perfor­mance curve is much steeper than that of compa­rable axial fans, and effi­ciency remains high, even when back pres­sure rises (Fig. 2). As a compact plug & play solu­tion with CE marking, the fans are easy to inte­grate into appli­ca­tions. Users won’t have to worry about nozzles or distance to the impeller, nor concern them­selves with conducting their own ErP assess­ment.

Thanks to the addi­tion of the new fans, the AxiEco series now covers a very broad range of appli­ca­tions. For example, the AxiEco Protect fan with guard grill is partic­u­larly well-suited for noise-sensi­tive appli­ca­tions, as its noise emis­sions are very low. By contrast, the AxiEco Perform fan with housing is recom­mended when a ready-to-install fan is needed. With air flows of up to 12,000 m³/h and pres­sures of up to nearly 500 Pa, they are ideal for a broad spec­trum of appli­ca­tions, ranging from heat pumps and evap­o­ra­tors to indus­trial venti­la­tion systems and the cooling of air compres­sors. The new fans with housing come in sizes 300, 350, 400, 450, and 500 and are avail­able in EC and AC design. Both the EC and AC vari­ants of this series also meet the require­ments of the future ErP Direc­tive and can be used for both exhaust and suction.

Fig. 2: The air perfor­mance curve of the AxiEco Perform is much steeper than that of the HyBlade, and it offers all that at a high effi­ciency. (Graphic| ebm-papst)

Aero­dy­namic design increases effi­ciency and air throw

Opti­mized aero­dy­namics lie at the heart of the fan’s design and are what help to increase effi­ciency and pres­sure: the impeller, inte­grated diffusor ring and hub form a compact unit and the blade tips pass over straight into the inte­grated diffusor ring. This elim­i­nates the head gap between the nozzle and the impeller, which also prevents air from flowing over the tips of the blades, as seen in conven­tional axial fans. The new design both increases effi­ciency and reduces noise. 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).

Fig. 3: Thanks to the inlet ring that immerses in the impeller, the large outlet opening, and the housing design, the AxiEco Perform fan has an optimum flow. (Graphic| ebm-papst)

The fan also features an aero­dy­nam­i­cally opti­mized housing with inte­grated guard grill and guide blades. Cavi­ties in the housing corners improve the flow; the guide blades ensure that the swirl in the outflow field of the fan, and thus the dynamic losses, are reduced to a minimum. The air throw is also higher compared to conven­tional axial fans (Fig. 4). This means that in large refrig­er­ated ware­houses for example, there is an even distri­b­u­tion of cold air, so fewer fans may suffice.

Appli­ca­tion-compat­ible design details

Fig. 4: The air throw from the AxiEco Perform is consid­er­ably better than from the HyBlade. (Graphic| ebm-papst)

In terms of exhaust-based appli­ca­tions, an optional guard grill can be attached to the intake side of the housing. If the fans are used for evap­o­ra­tors, an air bag that closes the air outlet opening during defrosting and when the fan is switched off can be easily installed. It is fixed to the cylinder-shaped housing using the stan­dard tensioning belt.

The air bag keeps the trapped heat in the evap­o­rator housing during the defrosting process. This signif­i­cantly reduces the defrosting time and makes for a low final defrosting temper­a­ture, thus saving a consid­er­able amount of energy.

The flow profile at the outlet of the AxiEco Perform fan ensures that the inte­grated guard grill does not freeze over as quickly, as there is back­flow – even at high back pres­sures. And the impeller with the inte­grated diffusor ring has been produced in highly resis­tant composite mate­rial, a mate­rial that, in and of itself, discour­ages icing. The grooves on the rear of the fan blades provide the neces­sary mechan­ical strength for achieving the high impeller speeds for the impres­sively high pres­sures. They also ensure that any water present can easily drain away in appli­ca­tions in which the fan has been installed with a vertical motor shaft.

Fig. 5: Different instal­la­tion methods for intake and exhaust oper­a­tion. (Graphic| ebm-papst)

Different instal­la­tion options and needs-based control

The sophis­ti­ca­tion of the housing design makes the fan easier to install and enables a number of poten­tial instal­la­tion methods (Fig. 5). For example, for intake oper­a­tion, the fans can be installed “on top”, i.e. on top of the customer’s device, or “semi-top” (recessed into the device). For exhaust oper­a­tion, the entire fan unit is installed in the customer’s device the other way around using the central flange and fitted with the intake-side guard grill. When used in venti­la­tion pipes, the central flange makes it easier to install the fan directly on the pipe system. This makes it easy to inte­grate the fans into venti­la­tion appli­ca­tions.

Fig. 6: The fans come in sizes 300, 350, 400, 450, and 500 and are avail­able in EC and AC design. With air flows of up to 12,000 m³/h and pres­sures of up to nearly 500 Pa, they are ideal for many different appli­ca­tions in refrig­er­a­tion, air condi­tioning, venti­la­tion tech­nology and mechan­ical engi­neering. (Graphic| ebm-papst)

The new AxiEco Perform fans satisfy the require­ments of the next ErP stage, regard­less of the motor tech­nology they have. 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. It is also possible to control and monitor the fans on a needs basis using a 0-10 V signal or MODBUS. These features help the EC fans to work very effi­ciently, partic­u­larly in the partial-load range, 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. The high speeds of the EC motors also provide much higher air perfor­mance, which are hugely welcomed for many indus­trial appli­ca­tions (Fig. 6).

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