There are several techniques existing for recovering energy from waste heat. The typical approach is to use waste heat to generate electricity. Now 3-D printing methods are taking the lead to make devices that will convert waste heat into electricity.
UNIST is located in the largest industrial city of Ulsan in Korea. Engineers there have conducted breakthrough research. They have developed a new thermoelectric technology for producing power-generating tubes. The best part of their research is they can print the tubes using 3-D printing methods.
Most automobile and industrial exhaust gases generally go to waste. But they are usually hot. By generating electricity from these hot exhaust gases, it is possible to enhance the efficiency of fossil energy production techniques. For this, the most suitable method is to use thermoelectric or TE methods. However, this is not an easy task, as typical thermoelectric products that the traditional processes produce are neither cost-effective nor do they fulfill efficiency requirements. According to the researchers, exhaust pipes fall into this category.
Engineers addressed this inefficiency issue by creating a special type of exhaust pipe. They built it out of lead and tellurium and used 3-D printing techniques for creating it. According to the researchers, they created the ink for the 3-D printer by mixing metal particles with a glycerol solvent. This provided them with the necessary viscoelasticity necessary for the ink and gave the ink the necessary characteristics of elasticity and viscosity.
The tube printed with this ink offers a high thermoelectric performance between temperatures of 400 and 800 °C. Most exhaust gases from vehicles exhibit this range of temperatures.
The research was a joint venture between the Department of Mechanical Engineering, UNIST, and the Department of Materials Science and Engineering, UNIST.
With their computational and experimental findings, the researchers have demonstrated the efficacy of their 3-D printed TE tubes they made from PbTe for power generation from waste heat. Their design has proven to be a system-adaptive and high-performance thermoelectric generator.
The 3-D printed power-generating PbTe TE tubes are made of p-type material and n-type material, with insulating material separating them. The TE tube has a series of p-type PbTe tubes followed by an insulating tube, and an n-type tube repeating many times. One complete power-generating TE tube may have ten pairs of p-type and n-type PbTe tubes in series.
According to the lead researcher, this 3-D printed power-generating PbTe TE tube technology can efficiently convert waste heat escaping through factory chimneys into electricity. In fact, factory chimneys are the most common type of source of waste heat. The shape of the tube makes it very effective for collecting heat as compared to the conventional rectangular shape of present TE generators.
Using 3-D printing technology for producing thermoelectric materials overcomes the limitations that engineers typically face while using commercial materials. According to the researchers, other fields can also use the viscoelastic characteristics that 3-D printed materials offer. The publication Advanced Energy Material features this novel and innovative research in thermoelectric materials.
