Heat pumps are already incredibly efficient. Researchers in Switzerland say they can push efficiencies even further using artificial intelligence.

A research team led by Jürg Alexander Schiffmann at the L'Ecole Polytechnique Fédérale de Lausanne (Swiss Federal Institute of Technology Lausanne, or EPFL) is using AI to design compressors that slash heat pumps’ electricity consumption by around 25 percent.

Unlike conventional furnaces or boilers, which combust fuels to generate heat, heat pumps use electricity to move heat from one place to another. Employing a compressor and refrigerant, heat pumps expel heat from the indoors to the outside during the cooling season, or capture heat outdoors from the ground or air and draw it indoors in winter.

The research in this case focused on the heat pump compressor. Conventional heat pumps use pistons to compress the circulating liquid refrigerant. The pistons must be oiled to avoid friction that can reduce heat transfer efficiency.

Here, the researchers’ design instead uses micro-turbocompressors 10 times smaller than the piston devices they replace. The micro-turbocompressors avoid friction by running without oil on gas bearings. According to the research team, by reducing friction the micro-turbocompressor system improves the heat pump’s heat transfer coefficient by 20 percent to 30 percent.

Schiffmann’s lab turned to machine learning to optimize the sizing of the micro-turbocompressor for each heat pump. The team entered the results from 500,000 simulations into machine-learning algorithms in order to generate equations used to populate heat pump design charts. The resulting equations can be used to right-size even very small compressors for different heat pump models.

According to the researchers, employing AI dramatically shortens and simplifies the heat pump design process.

On the market in five years?

Such micro-turbocharger technology is "mature," according to a press statement from EPFL. “'Mature' from our view means that we have proven the technical feasibility of such machines,” Schiffmann, an assistant professor based at EPFL’s Laboratory for Applied Mechanical Design, told Greentech Media in an email.

“A compressor manufacturer should be able to take our technology and incorporate it into their product development,” he added.

Still, Schiffmann cautioned that much work remains to commercialize the technology. “A significant industrialization step has to be performed before our machines can become an economically viable product."

The lab has thus far tested only prototypes of the micro-turbocompressor heat pumps.

“Producing hundreds of thousands or even millions per year calls for a significant redesign for mass-production,” he said. “My best guess is that heat pumps with micro-turbocompressors will become available on the market within approximately five years.”

Schiffmann said there is already industry interest in adopting the technology. "We have already been contacted by several companies that are interested in using our method," he added, without disclosing specific companies.

“They prefer to stay ‘under the radar’ for the moment," he said.