Energy-efficient cooling thanks to ionic wind

Data centers consume vast amounts of energy – around 40 percent of it for cooling microprocessors alone. Novel cooling methods using ionic wind could drastically curb energy consumption. These are based on electrostatic fields to convert electrical current directly and energy-efficiently into an airflow. The low speeds of the generated airflow have so far prevented widespread use. Now the Empa spin-off Ionic Wind Technologies has achieved a breakthrough: Their airflow amplifier accelerates – thanks to novel electrodes combined with a flow-optimized housing shape – ionic wind much more than before. If, say, conventional fans in data centers were replaced by their patented technology, up to 60 percent of cooling energy could be saved.

A patented amplifier

“We accelerate air directly by charging it electrically. Since the electric current is converted directly into an airflow, the energy-consuming and noisy intermediate steps via a motor, rotor or fan blade are eliminated,” says star-up founder Donato Rubinetti, explaining the basic principle of ionic wind. This has already been successfully used in a non-thermal drying process for fruit, developed at Empa. As part of an Innosuisse project, the technology was then further developed so that the airflow could be more than tripled.

At the heart of the patented airflow booster for ionic wind are so-called needle electrodes. These generate ionic wind much more efficiently than the previously used wires. But that’s not all: The needle tips are installed in a housing that makes use of the Coandă effect. This fluidic principle is also used in airplane wings or Dyson fans – it uses local pressure differences to multiply the volume of air flows. “In combination, these two innovations are a huge step forward and merge to form the so-called Ionic Wind Amplifier, which opens up completely new fields of application with significantly better performance,” says Rubinetti.

Taken to the extreme

So far, only standard products such as construction nails had been used as needle electrodes for ionic wind. “Our custom-made needle tips achieve up to twice the speed of the airflow compared to conventional electrodes – and with less energy,” says Donato Rubinetti. “A tip is not infinitely pointed, but still has a curve at the very end. This plays an extremely important role in the performance of the needle electrodes.” Initially, the air current amplifier was simulated with wires. However, these reacted differently in the laboratory than calculated on the computer, so Rubinetti’s team switched to needle tips.

An unexpectedly perfect solution for the Empa spin-off: This type of electrode not only creates a very strong asymmetry in the electrostatic field, which directs the air flow and thus amplifies it; the tips can also be accommodated much more compactly in housings than wires. “From that point on, it was all about systematically optimizing the tips,” recalls the spin-off founder.

However, manufacturing the needle tips to measure was anything but easy. He received advice and support from the workshop specialists at Empa in St. Gallen, who also produced the tungsten tips for the experiments and suggested ways to reduce costs. “For us as a start-up, it is absolutely crucial to be able to produce tips with identical properties in large quantities and at low cost in future,” says Rubinetti.

Energy consumption more than halved

According to Rubinetti, the technology is suitable for industries that rely on cooling systems, drying processes and air purification. “I see the potential wherever air needs to be moved with a small pressure difference. In future, however, above all in the cooling of computers, servers or data centers.” The patented Ionic Wind Amplifier has nothing to hide in comparison to conventional devices – on the contrary: Airflows can be moved up to 60 percent more efficiently. And depending on the application, even more energy can be saved: Especially when drying food, there is an additional efficiency gain at process level, as heating elements are no longer required.

Ionic Wind Technologies has already been awarded the “Startfeld Rohdiamant” prize by the St. Galler Kantonalbank for the best business idea. In addition, the spin-off funding program Venture Kick and the Gerbert Rüf Stiftung are providing financial support to the Empa spin-off as part of the InnoBooster program to bring the product to market maturity. “We produce the airflow amplifiers ourselves and want to sell components in the future. However, as we have patents and other ideas, a licensing model could also be conceivable,” says Donato Rubinetti, who is currently also funded by the Swiss National Science Foundation (SNSF) as a BRIDGE Fellow and is pursuing his ideas at Empa. “It won’t be easy, but we are solving important problems, which motivates us to keep going.”