Stay longer on the sea bed
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From left to right: Dr Tony Smith, Dr Lew Nuckols, Professor Stan Kolaczkowski, Dr Serpil Awdry
When divers explore the sea bed, their time underwater is limited by the availability of breathable air. Researchers from the Department of Chemical Engineering are developing a new system to remove carbon dioxide from gaseous streams, which could potentially increase the amount of time divers can spend underwater.
Professor Stan Kolaczkowski and his team are working in collaboration with mechanical engineers from Duke University, North Carolina.
Developing a compact solution
The current process for CO2 removal involves the diver carrying chemicals such as calcium hydroxide, Ca(OH)2, which chemically react with the CO2.
When developing a new system, the team are harnessing the potential of sea water to absorb CO2. The system is compact and allows the diver to freely explore the sea bed, eradicating the need to carry chemicals to remove CO2.
The technology
The new system uses sea water and Dixon rings. Based on technology developed in 1948, Dixon rings consist of a fine wire mesh folded into a ring, approximately 3 mm in size. The space in the wire mesh provides an extended surface area for mass transfer. Many rings are packed into a column through which gas and liquid flow in a counter-current direction.
The combination of salt water and Dixon rings form a compact gas scrubbing unit, which removes CO2 from a closed-circuit breathing environment before safely discharging it to the sea.
"Chemical engineers are excited about using Dixon rings in applications where gaseous or volatile species are transferred between gas and liquid phases and where the device needs to be compact," said Professor Kolaczkowski.
Making a real difference to the diving community
Dr Lew Nuckols of Duke University says: "An estimated 90 per cent of human-produced carbon dioxide is absorbed by oceans. Our research with the University of Bath could revolutionise techniques to remove metabolically-produced carbon dioxide from sub-sea operation.
"Being a diver, I am aware of the difficulties with supplying sufficient quantities of breathable air underwater. This research is looking at a very practical and elegant solution to a difficult problem."
The project is funded by a 3 year grant of $554,858 from the US Office of Naval Research (ONR).
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