Four-Stroke Engine Made Into Modular Reforming Reactor

[Guest_Jim_*]

Hydrogen can be a potent fuel but one issue that has been deviling the adoption of it and the technology that can use it has been transporting the gas. In order to move the gas around like conventional fuels are would practically require a whole new infrastructure, but researchers at Georgia Institute of Technology have developed a solution. Instead of producing the hydrogen in one place and then transporting to where it will be used, they have created a reforming reactor that can be deploy at the point of use, and it just so happens to be related to the internal combustion engine.

Modern means of creating hydrogen for use in fuel cells involves temperatures of around 900 ºC, takes three water molecules to create one hydrogen molecule, and the resulting gas is low density. Wanting to design a better reactor, the researchers started thinking about the features it needed, and these included the ability to change the size of reactor vessel. Looking at existing mechanical systems, the researchers realized the internal combustion engine, with its over one hundred years of development, provides this feature, so they figured out how to make a four stroke engine into the CO₂/H₂ Active Membrane Piston (CHAMP) reactor.

In the first stroke, with the piston moving down, natural gas (methane) and stream are pulled into the cylinder, and once the piston reaches the bottom of the cylinder, the valve closes. Next the piston starts moving up, compressing the steam and methane, and the cylinder is also heated so that at 400 ºC a catalytic reaction is started, creating hydrogen and carbon dioxide. A selective membrane allows the hydrogen to exit the cylinder while the CO₂ is pulled into a sorbent material mixed with the catalyst. Now when the piston lowers, reducing pressure as well, the CO₂ escapes the sorbent so it can be expelled when the piston starts moving up again. While the process does produce carbon dioxide, it, like the hydrogen, can be captured for later use or long term storage.

Though the CHAMP reactor does resemble a four-stroke engine, it operates much more slowly, completing few cycles per minute, compared to conventional engines that run in the thousands of RPMs. This speed and other factors of the modular design can be altered, so the supply of hydrogen can match the immediate demand, at the source of the demand. Combined with the existing natural gas infrastructure and this system can be used to get as much hydrogen as is needed almost wherever it is needed, whether that is fuel cells for houses, refueling stations for fuel cell vehicles, or even larger systems for powering neighborhoods.

Source: Georgia Institute of Technology

Back to original news post