Mobile air conditioning in rail vehicles

modern high speed train in the city in winterClick to enlarge
The air-conditioning systems in the ICE 3 class 403 train use ambient air for cooling.
Source: Deutsche Bahn AG

Rail vehicles include local and long-distance trains, suburban fast trains, underground trains and trams. The energy for heating is provided electrically or with diesel fuel. Mobile air conditioning systems in rail vehicles are usually charged with HFC refrigerants. HFCs, or hydrofluorocarbons, are very potent greenhouse gases.

Rail vehicle heating and cooling systems both produce greenhouse gas emissions. In Germany, some 23 tonnes of the refrigerant R134a leaked from rail vehicle air conditioning systems in 2020, which is equivalent to the greenhouse effect of 33,400 tonnes of CO2. The European Union intends to gradually reduce the production and use of HFCs and replace them with less harmful substances in a phase down approach regulated by the EU F-gas Regulation Nr. 517/2014.In some systems the combination of cooling with a heat pump function is possible which can reduce the energy needed for heating and therefore reduce CO2 emissions as well.

Alternatives to HFC air conditioning in the rail sector are refrigerant cycles with CO2 or systems based on air cycle technology. For CO2-based cycles, there were only a few tests in rail vehicles, whereas systems based on air cycles have been already in regular service for a number of years in one class of the ICE high-speed train. Reliable data on the economic efficiency of these techniques is now available. In a research project, optimized air conditioning system based on air-cycle technology had been tested in a train in regular service over a period of two years. Air conditioning systems based on air-cycle technology show advantages over usual air conditioning systems with fluorinated refrigerants in terms of energy efficiency and life cycle costs.

Currently, the German rail industry is investigating air conditioning systems based on hydrocarbons such as propane.

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 mobile air conditioning unit  air conditioning  railway traffic  CO2 air conditioning system