State-owned railroad company SNCF (National Society of French Railways) is purchasing 291 HVAC systems using air-cycle technology from Liebherr-Transportation Systems for inclusion in its regional high-capacity railcars.
Instead of using a chemical refrigerant, the system compresses, cools and expands ambient air (R729) to provide comfort cabin cooling, with partial load control. The new railcars, manufactured by Canada-based Bombardier Transportation, will operate in the Occitania region of France, with close proximity to the Pyrenees and the Mediterranean Sea.
“Since the [unit] consists of only a few components and the cooling circuit does not require pressure testing and evacuation, the air–based air–conditioning system is simple and cost-effective to maintain,” said Reinhard Aigner, Head of System Engineering at Liebherr in the company’s magazine OnTrack.
The technology: Liebherr originally designed the system for use in the aviation industry where it has provided cabin air-conditioning for decades.
- The roof-mounted system draws in air and passes it through a cooling turbine, which drops the temperature through depressurization.
- The cooled air absorbs cabin heat via a heat exchanger.
- The unit then recompresses the air to the ambient pressure, which reheats it and enables the surrounding environment to act as an “efficient” heat exchanger, according to Liebherr.
Proven performance: Air-cycle systems have been tested in two European countries: France and Germany.
- As part of the SNCFʼs “Eco-Clim” research program, the air cycle system was tested from 2015 to 2019 on the railroad’s high-capacity railcar (Autorail à Grand Capacité or AGC) trains operating in Occitania. “The systems demonstrated exceptional reliability, low energy consumption and significant environmental advantages,” Liebherr said.
- Deutsche Bahn also tested the air-cycle HVAC systems on its ICE 3 trains, with support from the German Federal Environmental Agency.
CO2/R290 options: In addition, Liebherr produces CO2 (R744) and propane (R290) HVAC systems for passenger trains.
- The company tested its CO2 HVAC unit in a Railjet fleet passenger coach operated by the Austrian Federal Railways (ÖBB) from May 2018 to August 2021. Compared to conventional air-conditioning systems, the CO₂ units increased energy efficiency by 30%. Liebherr started serial production of CO₂ HVAC units in 2024.
- Swiss rail manufacturer Stadler Rheintal will install 166 Liebherr R290 HVAC units in its new Nordic Express trains, with delivery from September 2024 to the end of 2026.
- Finland’s government-owned railway company VR Group will operate 20 regional FLIRT (fast light intercity and regional trains) trains equipped with Liebherr R290 HVAC systems. The contract includes 80 saloon units, 80 heat recovery units and 40 cab units, with delivery from September 2024 to December 2026.
Quotable: “Our air-cycle air-conditioning technology is the next step on the way to tomorrowʼs trains,” said Klaus Schneider, Chief Technology Officer at Liebherr–Aerospace and Transportation. “We are proud to contribute to eco-friendly travelling as well as to the comfort of the passengers on board Occitania AGC trains.”
