Hydrocarbon-based railway HVAC does without secondary loop

The European rail industry is embracing R290, a hydrocarbon refrigerant with a global warming potential (GWP) of 3 for train HVAC systems.

As well as aligning with the European Union’s F-Gas regulations and potential restrictions on PFAS substances, this shift marks a significant departure from high-GWP HFCs like R407C and R134a.

Liebherr Transportation Systems, a German-Swiss multinational manufacturer of systems and components for the rail industry, is taking a leading role in this transition by securing a significant order from Swiss rail manufacturer Stadler Rheintal for 166 propane-charged HVAC units for its new Nordic Express long-distance trains.

“We are very happy and thank our customer Stadler for the trust placed in us,” said Liebherr Transportation Systems deputy general manager Roland Friedrich.

Asked by SightGlass how flammability risks are handled and whether a secondary loop is used to prevent R290 getting into the rail carriages, Liebherr Transportation Systems head of corporate communication Ute Braam said: “The system considers all necessary safety case-related requirements and works with specifically designed, fully encapsulated heat exchangers to prevent any propane from entering the passenger compartment. There is no additional circuit.”

This approach, in compliance with rigorous TÜV Süd safety standards, eliminates the need for a more costly dual-circuit design.

Manufacturing of the HVAC units will take place at Liebherr’s Bulgarian factory and will be delivered to Stadler starting in early 2025, with full completion expected over “several years”. 

The units will be installed on 17 Nordic Express train sets, comprising 132 passenger cabins and 34 locomotive cabs.

Liebherr claims that servicing these propane units is no different than traditional systems, as technicians will follow established safety protocols for handling flammable refrigerants. “Our HVAC systems and service concepts take all necessary safety requirements,” said Friedrich. 

The adoption of propane HVAC systems is gaining momentum across Europe. Peter Danzer, Project Leader for German rail operator Deutsche Bahn, confirmed this trend at the ATMOsphere MAC Summit 2024 in Berlin.

“The attitude toward R290, deemed impossible in the past due to flammability, has fundamentally changed. We’ve had no registered issues with the refrigerant in our trains.”

Deutsche Bahn has been using propane HVAC units in its trains since 2022 and plans to have more than 2000 in operation by 2027.

Although globally the rail industry is still in the early stages of adopting hydrocarbon refrigerant-based HVAC systems, propane is proving to be a frontrunner, outperforming CO2 (R744) in this sector due to its superior cooling efficiency and lower power consumption.

“Propane is an efficient and eco-friendly refrigerant,” remarked Friedrich. “We therefore offer a reliable, in-service solution for more sustainable mobility.”