Scientists develop new thermoelectric materials: turning waste heat into electricity.
energy produced by ordinary automobile fuel, only about 1/3 of the energy is effectively used, and the rest of the 2/3 are discharged directly to the environment by the form of waste heat. This not only wastes energy, but also creates great pressure on the environment. A thermoelectric semiconductor material developed by American scientists can not only capture these wasted energy sources, but also convert them into electricity for use in cars, according to an article published on May 26th in the American Journal of technical review. The thermoelectric device made of this material is expected to increase the fuel economy of existing cars by 3% to 5%, researchers said.
currently, BSST and General Motors Corporation global R & D center are conducting independent research and testing. BSST will conduct tests on BMW and Ford cars, while GM chooses Chevrolet SUV. The two companies choose the loading test time at the end of summer.
bismuth telluride is a common thermoelectric material, which contains expensive tellurium, with a maximum working temperature of only 250 degrees Celsius, but a thermoelectric generator can reach a maximum temperature of 500 degrees centigrade. So BSST uses another thermoelectric material, a mixture of hafnium and zirconium, which not only works well at high temperatures, but also increases the efficiency of the thermoelectric generator by 40%.
common researchers are using another kind of thermoelectric material, cobalt and arsenic compounds, and some rare earth elements such as ytterbium are mixed. This material is not only cheaper than telluride, but also works at high temperature.
General Motors scientist Gregory Meissner said that the whole process of the experiment is very long and complicated. Because of the huge temperature gradient, there is a great mechanical stress on the thermoelectric material interface. Therefore, how to keep the material and the car to keep good electrical and thermal contact has become a technical difficulty. In addition, the addition of different substances will increase the heat resistance and increase the resistance of thermoelectric materials. How to reduce this effect is also a challenge. Through the efforts of scientists to successfully solve these problems, general computer simulations show that the Chevrolet Suburban test vehicle equipped with this thermoelectric device can generate 350 watts of electricity and can increase the fuel economy of Suburban by 3 percentage points.
after solving the basic technical problems, the perfect fusion of the Thermoelectric equipment and the existing vehicle equipment has become the focus of the researchers. Although researchers have installed bismuth telluride into a SUV by inserting a car exhaust system in the test, Meisner is not satisfied with it. "It looks like a muffler, and we need to design products that are more integrated with the vehicle, not an additional device."
Meisner said that because the cost of producing these materials remains to be further reduced, it may take about 4 years to go into business.