When CO₂ interacts with the solvent, it produces heat that can diminish the capability of the solvent to react with CO₂. Reducing this localized temperature spike in the column through cooling channels helps increase the efficiency of CO₂ capture.

“Prior to the design of our 3D printed device, it was difficult to implement a heat exchanger concept into the CO₂ absorption column because of the complex geometry of the column’s packing elements. With 3D printing, the mass exchanger and heat exchanger can co-exist within a single multifunctional, intensified device,” said ORNL’s Xin Sun, the project’s principal investigator.

Embedded coolant channels were added inside the packing element’s corrugated sheets to allow for heat exchange capabilities. The final prototype measured 20.3 centimeters in diameter, 14.6 centimeters in height, with a total fluid volume capacity of 0.6 liters. Aluminum was chosen as the initial material for the intensified device because of its excellent printability, high thermal conductivity, and structural strength.

“The device can also be manufactured using other materials, such as emerging high thermal conductivity polymers and metals. Additive manufacturing methods like 3D printing are often cost-effective over time because it takes less effort and energy to print a part versus traditional manufacturing methods,” said Lonnie Love, a lead manufacturing researcher at ORNL, who designed the intensified device.

The prototype demonstrated that it was capable of substantially enhancing carbon dioxide capture with the amine solution, which was chosen because its highly reactive to CO₂. In results published in the AIChE Journal, ORNL researchers conducted two separate experiments — one that varied the CO₂-containing gas flow rate and one that varied the MEA solvent flow rate. The experiments aimed to determine which operating conditions would produce the greatest benefit to carbon capture efficiency.

Both experiments produced substantial improvements in the carbon capture rate and demonstrated that the magnitude of the capture consistently depended on the gas flow rates. The study also showed a peak in capture at 20% of carbon dioxide concentration, with percent of increase in capture rate ranging from 2.2% to 15.5% depending on the operating conditions.

“The success of this 3D printed intensified device represents an unprecedented opportunity in further enhancing carbon dioxide absorption efficiency and demonstrates proof of concept,” Sun said.

Future research will focus on optimizing operating conditions and device geometry to produce additional improvements in the carbon capture absorption process.