Numerical investigation on the heat and mass transfer enhanced by Triply-Periodic-Minimal-Surface (TPMS) configuration in flow chemistry

In the world of making medicines and chemicals, the way reactions are run has shifted dramatically in recent decades. Instead of mixing ingredients in a large, open vat where heat can build up unpredictably and safety is a constant worry, scientists now prefer to push fluids through narrow, continuous tubes. This method, known as flow chemistry, offers superior control and safety because the reaction happens in a tiny, moving stream rather than a massive pool. However, as engineers try to move these processes from a small laboratory bench to a factory floor, they hit a stubborn wall. When you simply make the tubes wider to handle more material, the ability to control heat and mix the chemicals evenly often breaks down. The reaction might get too hot in the middle, creating unwanted byproducts or even causing an explosion, while the edges remain cool. The challenge is to design a reactor that stays efficient and safe even as it grows larger, without losing the precise control that makes flow chemistry so valuable in the first place.

To solve this, researchers at Xi'an Jiaotong University and Hebei University of Technology have developed a new type of reactor based on a complex, repeating geometric shape called a triply periodic minimal surface. Imagine a structure that looks like a sponge but is made of smooth, continuous curves that twist and turn in three dimensions, creating a maze of interconnected channels. This specific shape, known as a gyroid, was chosen because it avoids the dead corners where fluid can get stuck and offers a massive surface area for heat to escape. The team built a prototype of this reactor with a characteristic size of 6 millimeters and compared it against two traditional tube reactors, one with a 2-millimeter diameter and another with a 4-millimeter diameter. Their goal was to see if this intricate, sponge-like design could maintain perfect temperature control and mixing as the system scaled up, a feat that standard tubes struggle to achieve.

The researchers did not just build the device; they created a detailed digital twin of it to watch how the fluids moved and reacted inside. They simulated a chemical process involving the production of vinylidene chloride, a material used in many industrial products, which involves mixing two liquids that react to release heat. By running these simulations alongside real-world experiments, they could measure how long the fluid stayed in the reactor and how evenly the temperature was distributed. The results showed that the fluid moving through the gyroid reactor behaved almost exactly like a solid plug, moving forward in a tight, organized line with very little mixing backward or getting lost in dead zones. This is the ideal behavior for a chemical reactor, ensuring that every drop of fluid experiences the same conditions. In contrast, the larger traditional tube showed signs of fluid bypassing, where some liquid moved too quickly through the center while other parts lingered, leading to inconsistent results.

When the team tested how well these reactors could handle heat, the advantages of the gyroid design became even clearer. In a scenario where the chemical reaction released a massive amount of heat—simulating a highly energetic industrial process—the traditional tubes struggled to keep the temperature down. The larger tube, in particular, allowed hot spots to form, which can ruin the quality of the final product by encouraging unwanted side reactions. While the 2-millimeter tube actually demonstrated the best overall heat transfer performance, the gyroid reactor came in a close second and showed a distinct advantage in a specific scenario: when side reactions became the dominant factor. Under these extreme conditions, the gyroid design's ability to maintain a steady temperature resulted in slightly higher selectivity, meaning it produced the desired chemical with fewer impurities compared to the other reactors. This ability to suppress unwanted side reactions is a critical factor for pharmaceutical manufacturing.

The implications of this work extend beyond just one type of chemical reaction. The researchers demonstrated that their computer modeling method, which combines fluid dynamics with chemical reaction rates, is a powerful tool for predicting how a reactor will perform before it is ever built. This approach allows engineers to test different designs on a computer with reasonable speed and accuracy, saving time and money on physical prototypes. The study suggests that the gyroid-based reactor could be a game-changer for processes that are currently too dangerous or difficult to scale up, such as nitration or lithiation, where heat control is a matter of safety as much as efficiency. By proving that this intricate, 3D-printed structure can handle the demands of industrial-scale chemistry while maintaining the precision of a lab experiment, the researchers have offered a promising path forward for the future of continuous flow manufacturing.