华盛顿D.C.，2014年7月15日 - 从您的热门汽车到您的温暖笔记本电脑，每一台机器和设备都会通过丧失热量来浪费大量的能量。但热电装置，将热量转换为电力，反之亦然，可以利用这种浪费的热量，并且可能提供可持续未来所需的绿色技术能源效率。
现在，一项新的研究表明，多孔物质如何充当热电材料 - 指向工程在未来热电装置中使用这种材料的方式。
世界各国科学研究中心中心的Dimitris Niarchos在希腊雅典的国家德莫斯中心的Dimitris Niarchos表示，大约70％的热量浪费了。他和Roland Tarkhanyan，也是NCSR Demokritos，在AIP发布中发表了他们在Journal APL材料中的分析。
To create the technology needed to capture this heat, researchers around the world have been trying to engineer more efficient thermoelectric materials. One promising material is one that’s filled with tiny holes that range in size from about a micron (10-6 meters) to about a nanometer (10-9 meters). “Porous thermoelectrics can play a significant role in improving thermoelectrics as a viable alternative for harvesting wasted heat,” Niarchos said.
Heat travels through a material via phonons, quantized units of vibration that act as heat-carrying particles. When a phonon runs into a hole, it scatters and loses energy. Phonons thus can’t carry heat across a porous material as efficiently, giving the material a low thermal conductivity, which turns out to increase the efficiency of heat-to-electricity conversion. The more porous the material, the lower the thermal conductivity, and the better it is as a thermoelectric material.
So far, however, researchers have yet to systematically model how porous materials maintain low thermal conductivity, Niarchos said. So he and Tarkhanyan studied the thermal properties of four simple model structures of micro-nano porous materials. This analysis, Niarchos says, provides a rough blueprint for how to design such materials for thermoelectric devices.
总的来说，研究人员发现毛孔越小，它们夹持在一起，导热率越低。Niarchos表示，他们的计算与其他实验中的数据相匹配。他们还表明，原则上，微纳米多孔材料可以在将热量转换为电力时几倍，而不是如果材料没有孔隙。
第一模型描述了填充有随机尺寸孔的材料，从微米直径到纳米。第二个是具有多层的多层，其中每层包含不同尺寸的尺寸的孔，这使其给出了不同的孔隙率。第三是由一个相同孔的三维立方晶格组成的材料。第四是另一个多层系统。但在这种情况下，每层包含一个立方格的相同孔。每层孔的尺寸不同。
According to the analysis, the first and fourth models have lower thermal conductivities than the second. The third model seems to be the best one, as it also has a lower thermal conductivity than the fourth model.
然而，除了第一个模型之外，所有模型都不是实用的，因为它们表示具有完美布置的理想情况，Niarchos表示。几乎不可能创造精确相等的毛孔。这是第一个模型是最逼真的。
Still, he said, all the distinct models demonstrate the importance of porosity in thermoelectric materials. Built upon simple and general analytical formulas, the models allow for a very fast and accurate computation of the effective lattice thermal conductivity of a porous material and the systematic analysis of such materials.
For more information, visitwww.aip.org.。
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