“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 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.”