© Lukas Zwiessele

So much cooler!

The smallest evap­o­rator series from Walter Roller GmbH is making leaps and bounds in effi­ciency with help from a compact fan. Despite gaining an addi­tional Flow­Grid, it is getting even smaller.


“The pandemic perma­nently changed sales work. I am not even here very often anymore,” says Rudi Wein­mann. “We use video calls to discuss a lot of things.” By “here” he means Walter Roller GmbH in Gerlingen. By “we” he means Wolf­gang Krenn, Managing Director of Roller, Ingo Raisch, Head of Devel­op­ment and Exper­i­ments, and, of course, Wein­mann, Head of Sales at ebm-papst for the Stuttgart region. Both compa­nies have been working together for around 25 years. While video calls, ushered in by the pandemic, have facil­i­tated commu­ni­ca­tion, it is clear to all three of them that on-site visits are some­thing that cannot be replaced.

The latest evidence for that is the V-Cooler project. The smallest evap­o­rator series from Roller that is very popular as well, cools drinks and meals in all types of refrig­er­a­tion units and bar coun­ters. It has been part of the company’s range since the 1980s.

During a busi­ness trip to Roller for another project, the three took a walk around the produc­tion area. The shaded-pole motor that drove the fan in this evap­o­rator series attracted Weinmann’s atten­tion: with a 10 percent effi­ciency level, it was not really state of the art anymore. Yet, Roller is a pioneer in using highly effi­cient EC tech­nology in its air coolers.

Wolf­gang Krenn, Rudi Wein­mann and Ingo Raisch (from left to right) on a tour of the produc­tion facility in Gerlingen. (Photos | Lukas Zwies­sele)

Ingo Raisch points out what is impor­tant for the V-Cooler: the cooling unit must be compact.

Rudi Wein­mann holds the solu­tion in his hands: a highly effi­cient AxiACi compact fan combined with the Flow­Grid air inlet grille.

Despite Flow­Grid as an addi­tional compo­nent, the new V-Cooler is even narrower than the previous model.

“From then on, Rudi worked on us for a rela­tively long time to imple­ment an effi­cient fan for this project as well,” Wolf­gang Krenn describes what happened. However, the fact that there is strong compe­ti­tion on the market for this type of evap­o­rator with providers offering cheap prices, was an argu­ment against a quick change.

“These are mass-produced goods,” Krenn explains. “When a part like that fails, it is replaced with a new one in no time at all. Users look very closely at the price.” However, in a special appli­ca­tion, the old shaded-pole motor reached its limits one day and kept failing. “Then we said: let’s move to EC.”

Compact fan + Flow­Grid = 15 mm narrower

Space is an impor­tant issue in refrig­er­ated units: if the air cooler is large, there may be fewer rows avail­able for drinks bottles. There­fore, the evap­o­rator needs to be extremely compact and the instal­la­tion space avail­able in the narrow cooler is corre­spond­ingly small.

Yet there are still strin­gent require­ments. Firstly, the air that flows over the chilled goods is drawn into the fan with a 90-degree deflec­tion. Secondly, evap­o­ra­tors in the catering sector come into contact with corro­sive substances, such as vinegar and cleaning agents, so they require resis­tant compo­nents.

Compact, powerful and quiet

The V-Cooler is not only very quiet thanks to the Flow­Grid air inlet grill, it is even 15 mm narrower despite this addi­tional compo­nent. The AxiACi increases the air output by up to 15 percent and the power consump­tion is also impres­sive: Instead of 20 watts for the shaded-pole motor, the EC compact fan only requires 4.4 watts. This means that the cooling unit quickly pays for itself for the user.

This led to a broad range of exper­i­ments and tests being carried out with different motors and fans that were powerful, robust and, most impor­tantly, small enough. Yet none of them were quite the perfect solu­tion. In 2021, the new AxiACi compact fan devel­op­ment with inte­grated elec­tronics seemed to be the ideal candi­date. “However, it gener­ated disrup­tive noise because of the low instal­la­tion depth and the required 90-degree air deflec­tion,” explains Head of Devel­op­ment Ingo Raisch. “Then, I got the idea to mount a Flow­Grid on the inlet side.”

This led to in-depth discus­sions with the Product Manage­ment team at ebm-papst. They performed sound measure­ments. The tests confirmed that this air inlet grill improved the flow condi­tions so much that the sound power level fell by around 7 dB(A), with approx­i­mately the same air flow.

Another high­light: because the fan is very compact and its guard grill is flat compared to its prede­cessor, Roller can make the evap­o­rator 15 millime­ters narrower, despite the addi­tional Flow­Grid. Raisch was very happy: “In a rela­tion­ship like this one, it is impor­tant that the imple­men­ta­tion is quick. And ebm-papst always fulfills that.”

The combi­na­tion of AxiACi and Flow­Grid makes the compact V-Cooler unique. (Photo | Lukas Zwies­sele)

The cooler makes savings already in its box

The solu­tion with the EC compact fan improves the air perfor­mance by up to 15 percent and provides a better flow through the heat exchanger. The evaporator’s effi­ciency levels are out of this world: rather than 20 watts of power consump­tion with the shaded-pole motor, the AxiACi requires only 4.4 watts. In cooling appli­ca­tions, the evap­o­ra­tors operate around the clock and elec­tricity costs are high, so the high-effi­ciency V-Cooler pays off for the user very quickly. “Rudi came up with the phrase ‘The cooler makes savings already in its box’,” says Wolf­gang Krenn with a grin, “we imme­di­ately started using it in our marketing.”

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