Pyroelectric energy conversion: Optimization principles
Pyroelectric energy conversion: Optimization principles
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DOI：
10.1109/tuffc.2008.680
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发表时间：
2008-03-01
影响因子：
3.6
通讯作者：
Guyomar, Daniel
中科院分区：
文献类型：
--
作者：
Sebald, Gael;Lefeuvre, Elie;Guyomar, Daniel
在微型发电机的框架下，本文介绍了使用铁电材料从温度中获取能量的要点。热电器件利用温度的空间梯度，而铁电材料需要温度的时间波动，从而导致不同的应用目标。铁电材料可以完美地收获可用的热能，而无论材料性质如何（受卡诺转换效率的限制），而热电材料的效率受材料性质（ZT品质因数）的限制。然而，它表明，卡诺循环所需的电场是远远超出了体铁电材料的击穿极限。薄膜可能是一个很好的解决方案，上升到超高电场和突出的效率。不同的热力学循环的文件中提出：原则，优点和缺点。使用卡诺循环，收集的能量将与材料性质无关。然而，使用更现实的循环，能量转换效率仍然取决于材料的性质，如本文所讨论的。定义了一个特定的耦合因子来量化和检查热释电能量收集的有效性。与机电耦合因子类似地定义为k（2）= p（2）θ（0）/（ε（θ）（33）c（E）），其中p、θ（0）、ε（θ）（33）、c（E）分别是热释电系数、最大工作温度、介电常数和比热。的重要性的的耦合因子的示出和讨论作为一个能量收集的品质因数。它给出了所有能量收集技术的有效性（卡诺循环除外）。结果表明，采用< 111 >0.75Pb（Mg_（1/3）Nb_（2/3））-0.25PbTiO_（3）单晶和电感上的同步开关收获，可以获得很高的效率（接近卡诺效率的50%）。最后，热释电能量收集的实际实施要点，表明不同的热力学循环是可行的，潜在的有效性，即使相比热电装置。
In the framework of microgenerators, we present in this paper the key points for energy harvesting from temperature using ferroelectric materials. Thermoelectric devices profit from temperature spatial gradients, whereas ferroelectric materials require temporal fluctuation of temperature, thus leading to different applications targets. Ferroelectric materials may harvest perfectly the available thermal energy whatever the materials properties (limited by Carnot conversion efficiency) whereas thermoelectric material's efficiency is limited by materials properties (ZT figure of merit). However, it is shown that the necessary electric fields for Carnot cycles are far beyond the breakdown limit of bulk ferroelectric materials. Thin films may be an excellent solution for rising up to ultra-high electric fields and outstanding efficiency.Different thermodynamic cycles are presented in the paper: principles, advantages, and drawbacks. Using the Carnot cycle, the harvested energy would be independent of materials properties. However, using more realistic cycles, the energy conversion effectiveness remains dependent on the materials properties as discussed in the paper. A particular coupling factor is defined to quantify and check the effectiveness of pyroelectric energy harvesting. It is defined similarly to an electromechanical coupling factor as k(2) = p(2)theta(0)/(epsilon(theta)(33)c(E)), where p, theta(0), epsilon(theta)(33), c(E) are pyroelectric coefficient, maximum working temperature, dielectric permittivity, and specific heat, respectively. The importance of the electrothermal coupling factor is shown and discussed as an energy harvesting figure of merit. It gives the effectiveness of all techniques of energy harvesting (except the Carnot cycle). It is finally shown that we could reach very high efficiency using < 111 > 0.75Pb(Mg1/3Nb2/3)-0.25PbTiO(3) single crystals and synchronized switch harvesting on inductor (almost 50% of Carnot efficiency). Finally, practical implementation key points of pyroelectric energy harvesting are presented showing that the different thermodynamic cycles are feasible and potentially effective, even compared to thermoelectric devices.