Heat is a byproduct of almost all electrical appliances and industrial processes, to drive a car to fly a plane or operating a power plant. Engineering researchers at Rensselaer Polytechnic Institute have developed new nanomaterials that could lead to techniques to better understand and make this waste heat to work. The main ingredients to make marble-sized pellets of new materials are made of aluminum and a common microwave oven every day.
The collection of waste heat from electricity requires the material, which is a good conduct electricity, but a poor heat conduction. One of the most promising candidates in this work is zinc oxide, non-toxic, low-cost material has a high melting point. Although the nano-engineered techniques exist to improve the electrical conductivity of zinc oxide, the material of high thermal conductivity is a roadblock to the efficient collection and conversion of waste heat. Since the characteristics of thermal and electrical conductivity, it is very difficult to calculate the one without the other also.
However, a team of researchers led by Ganpati Ramanath, professor of materials science and engineering at Rensselaer, in collaboration with the University of Wollongong, Australia, showed a new way to reduce the thermal conductivity of the oxide zinc without reducing the electrical conductivity. The innovation is to add small amounts of aluminum to zinc oxide and materials processing in a microwave oven. The process is adapted from a technique invented by the Rensselaer Ramanath, graduate students Rutvik Mehta, and Theo Borca-Tasciuc, associate professor in the Department of Mechanical, Aerospace and Nuclear (MANE). This could open the door to new technologies for harvesting waste heat and create energy-efficient cars very efficient, aircraft, power plants and other systems.
"The collection of waste heat is a very attractive proposition because it can convert heat into electricity and used to power a device - like a car or plane -. That generates heat in the first place would lead to greater efficiency almost everything we do and ultimately reduce our dependence on fossil fuels, "Ramanath said. "We are the first to demonstrate such favorable largest thermoelectric properties of materials at high temperatures, and we believe our discovery will pave the way for new devices for energy recovery of waste heat."
The study results are detailed in a recent article published in the journal Nano Letters.
To create a new nano-materials, the scientists added small amounts of nanocrystalline zinc aluminum oxide to modify the wizard, and $ 40 are heated with microwaves. Ramanath team is able to produce several grams of nanomaterials in a few minutes, which is sufficient to create a device to measure a few inches long. The process is less expensive and more scalable than traditional methods and is environmentally friendly, Ramanath said. Unlike many of nanomaterials, which are produced directly from the substrate or surface, a new microwave method can be used for the production of pellets of nanomaterials that can be applied to different surfaces. These characteristics, combined with high thermal conductivity and electrical conductivity, are suitable for applications in the heat of harvest.
"Our discoveries may be the key to overcoming the fundamental challenges associated with working with thermoelectric materials," said project collaborator Borca-Tasciuc. "In addition, our process is likely to be wide-scale production. It is truly amazing that some aluminum atoms can conspire to give us the thermoelectric properties of interest to us"
This work was a collaborative effort between the Dou and Shi Xue Ramanath, professor at the Institute for Superconducting and Electronic Materials Wollogong University, Australia. Wollongong, graduate student Priyanka Jood job done in collaboration with Rensselaer graduate students and Zhang Yanliang Mehta Jood Rutvik more than a year visiting Rensselaer. Co-authors are Richard W. Siegel, Robert W. Hunt Professor of Materials Science and Engineering, along with teachers and Wang Xiaolin Germanic Peleckis at the University of Wollongong.
This research is funded by support from IBM through the Rensselaer Nanotechnology Center; S3TEC, a research center on the border energy funded by the U.S. Department of Energy (DoE), Office of Basic Energy Sciences, the Australian Research Council (ARC) and University of Wollongong.
