Heating and cooling systems are some of the biggest energy guzzlers in use, so passive temperature control could be a good way to reduce emissions. Phase-change materials (PCMs) show promise for this, and now engineers at Texas A&M have developed a new PCM composite that can be 3D printed.
The name “phase-change materials” is pretty self-explanatory – these materials will switch between phases of matter as the temperature changes. One of the most promising applications for this technology is insulation: the PCM melts into a liquid as it absorbs heat, cooling its surroundings. As the ambient temperature cools, the material will solidify again, releasing its stored heat.
In the past, PCMs have been used in coffee cups to keep hot drinks hot, fabrics that keep wearers warm or cool as needed, liquid coatings that prevent frost build-up, and in building materials that better regulate indoor temperature. It’s that last one that the researchers on the new study wanted to improve.
Previous PCMs have been rather inefficient and costly, because they need a shell to contain their liquid form. That means pellets of PCMs need to be embedded into a building material, but fewer of them can fit in that form, and it can be difficult to scale that production.
For the new study, the Texas A&M researchers looked to mix a PCM directly into a building material. They mixed paraffin wax, as the PCM, with liquid resin as the supporting structure, creating a soft, paste-like material that can be shaped as needed. Once it’s in the desired shape, it can be cured with UV light to harden the resin.
The end result is a solid material strong enough to build with, containing pockets of PCM inside. Without the need for extra shells, the PCM can be packed in more densely, comprising up to 63 weight percent of the material, which boosts its ability to regulate the ambient temperature.
But perhaps most importantly, the material is now easier to make in bulk. Its squishiness means it can be made into a 3D-printable ink, which could then be made into whatever shape or size is desired, for much lower cost than other PCM building materials.
“The ability to integrate phase-change materials into building materials using a scalable method opens opportunities to produce more passive temperature regulation in both new builds and already existing structures,” says Dr. Emily Pentzer, an author of the study,
The team demonstrated the new material by printing and curing a small hollow house model. When this model was placed in an oven, the hollow interior was 40 percent cooler than the external environment. The material also showed almost no leakage of the PCM over 200 cycles of melting and solidifying.
The researchers say they will experiment with different PCMs to see if they can extend the temperature range at which they operate. This could help them reduce energy costs associated with running heating and cooling systems.
“We’re excited about the potential of our material to keep buildings comfortable while reducing energy consumption,” says Dr. Peiran Wei, an author of the study. “We can combine multiple PCMs with different melting temperatures and precisely distribute them into various areas of a single printed object to function throughout all four seasons and across the globe.”
The research was published in the journal Matter.
Source: Texas A&M University