Language
Country/Area
No result found
The mysterious power of thermoelectric materials: Why can they turn heat into electricity?
The scientific community has long been fascinated by a mysterious phenomenon: the thermoelectric effect. Thermoelectric materials can convert thermal energy into electrical energy, or vice versa, under the action of temperature differences. This effect has many potential practical applications, from waste heat recovery systems to sophisticated cooling technologies, and could even serve as a building block for future energy solutions. This article takes a closer look at how thermoelectric materials work and their potential for modern technology.
Basics of Thermoelectric Effect
There are three main forms of thermoelectric effect: Seebeck effect, Peltier effect and Thomson effect.
The Seebeck effect is when a temperature difference occurs and a voltage is generated in the material; the Peltier effect is when current drives the flow of heat; and the Thomson effect is when current and temperature gradient act simultaneously and reversibly. heating or cooling phenomenon.
While most materials have some thermoelectric effect, in many cases the effect is too small to be of practical use. Discovering low-cost materials with sufficiently strong thermoelectric effects has become the focus of current research. Bismuth telluride (Bi2Te3)-based thermoelectric materials are the most common on the market today and are used in thermoelectric systems for cooling or heating.
Superior performance of thermoelectric materials
The key to evaluating a material's usefulness in thermoelectric systems is its efficiency, which depends on the material's thermal conductivity, electrical conductivity and Seebeck coefficient, which vary with temperature.
The superiority of thermoelectric materials is often characterized by the thermoelectric figure of merit Z (ZT), which is a comprehensive indicator that can be used to predict its maximum efficiency in the energy conversion process.
The calculation formula of Z involves the electrical conductivity, Seebeck coefficient and thermal conductivity of the material. Different combinations will affect the overall performance of the material. Recent studies have shown that increasing the Seebeck coefficient while reducing thermal conductivity can significantly enhance the thermoelectric effect.
Efficiency and power factor of thermoelectric devices
The efficiency of a thermoelectric device is defined as the ratio of the energy delivered to the load to the heat absorbed at the hot junction. Although this may seem simple, in practice, improving equipment efficiency is a very complex task.
The coefficient of performance of current commercial thermoelectric cooling devices ranges from 0.3 to 0.6, which is only a fraction of the performance of traditional vapor compression cooling devices.
In addition, the thermoelectric power factor is another important parameter, which reflects the energy that a material can generate in a specific shape and configuration. The higher the power factor, the more energy converted by the thermoelectric material.
The Importance of Material SelectionStrategies to optimize thermoelectric performance include utilizing materials with high electrical conductivity, low thermal conductivity, and high Seebeck coefficient. Semiconductor materials are generally considered to be ideal thermoelectric materials, mainly because of their band structures.
The Fermi level of semiconductor materials is below the conduction band, which allows them to efficiently carry out carrier movement and enhance the thermoelectric effect.
In addition, in order to improve efficiency, the competitive relationship between thermal conductivity and electrical conductivity must be balanced. Reducing lattice thermal conductivity is the key to improving overall performance.
Directions for future research
As research into thermoelectric materials deepens, possible future breakthroughs may include the development of new alloys, complex crystals, and multiphase nanocomposites. These new materials can not only improve thermoelectric performance, but also effectively address the thermal conductivity problem of materials.
In the future, thermoelectric technology may be able to be applied in a wider range of areas and create more sustainable energy solutions.
In summary, thermoelectric materials not only play a key role in energy conversion technology, but also have unlimited possibilities in the development of environmentally friendly technology in the future. So, how big a role do you think thermoelectric materials will play in future green technology?
