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Commercialising adsorbent fibre technology for transport systems

The success of our spin-out company has seen our research on structured adsorbents applied across the rail sector to improve rolling stock efficiency.

Dr Semali Perera holds filter sticks with gas coming out of the ends
Low friction adsorption materials can result in huge environmental savings.
‘Improvements to processes at the nano scale can have application and impact in many different sectors. Taking research to the market is tough though, you have to be really passionate about your technology to succeed.’
Semali Perera Professor of Chemical Engineering

Keeping trains on track

From pneumatic doors to self-levelling air suspension to train horns, rail networks rely on compressed air systems. Without a supply of clean, dry air, components fail due to corrosion and trains grind to a halt. Costly for train companies and frustrating for passengers.

For years trains have relied on aftercoolers, adsorbent beads or membrane dryers to remove moisture and impurities from the air. But these methods are often unreliable and need frequent replacements. Keeping our rolling stock on track requires a reliable and durable dry air system. And the key to this is absorbent fibre technology.

Environmentally friendly gas separation

At Bath, we’ve been making and testing adsorbent materials for over 20 years. Unlike absorption where fluid dissolves into a liquid or a solid, adsorption sees molecules form an adhesive film along a surface or membrane. This means these materials are totally resistant to bulk water and there’s no by-product or chemical reaction when they are saturated.

Air compressors are mainly found under the body of a train carriage. They draw in air from the atmosphere surrounding them, which usually contains water vapour and contaminants. As the air is compressed these impurities are compacted together, then they are cooled to form a liquid that can be easily removed by depressurisation. This process requires a large pressure drop from beginning to end.

Separating gases at a reduced pressure drop uses less energy, which is better for the environment and a much more sustainable option for industry. Our patented hollow fibre method allows us to do just that. These structured, straight channels reduce friction and drag to keep the pressure drop low compared to adsorbent bead-filled dryers.

Adsorption hollow fibres

Our technology could also have applications in manufacturing, aerospace, transport and food industries.


In recognition of this innovative new technology, Professor Perera was presented with the Royal Society’s prestigious Brian Mercer Award for Innovation. The prize money from the award helped to create a spin-out company from the University called Nano-Porous Solutions Ltd (n-psl) with patent rights to our hollow fibres.

Taking research to the production line

By October 2013 Nano-Porous Solutions Ltd (n-psl) had created 24 new jobs and an annual financial turnover of over £1 million. That same year international engineering group IMI plc purchased n-psl and they became part of the Norgren Group. Our absorbent fibre technology was incorporated into the Adsorbent Media Tube (AMT) technology sold by Norgren within its Rail Dryer range.

Now, more than 700 Norgren AMT systems are supplied each year to railway systems across Europe, Asia, North America and Australia. Unlike many other air drying systems that need to be replaced every 6 to 24 months, Norgren AMT systems last up to ten years. This, coupled with the low pressure drop means that in the rail industry alone, it’s estimated Norgren AMT technology could save millions of tonnes of carbon dioxide emissions by 2050.

Thanks to a more reliable air drying system, trains carrying AMT technology can stay on track for longer, offering passengers a more consistent and cost-efficient service.

Norgren and the University of Bath are still working together through a Knowledge Transfer Partnership to improve production rates of AMTs as well as looking to launch brand new products.

‘With greater reliability and reduced need for maintenance, the AMT drying system incorporating University of Bath research, benefits rail transportation companies, passengers and the environment.’
Gary Manning Senior Mechanical Engineer and AMT Team Leader

Find out more about our research activities

Chemical engineering research
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