论文标题
碳纳米管冰箱的高性能在较大的温度范围内
High performance of carbon nanotube refrigerators over a large temperature span
论文作者
论文摘要
温室气体的压缩仍然主导着冷藏设备的市场。尽管稳定且高效，但该技术既不安全，也无法缩放到纳米级。正在开发固态冷却技术以克服这些局限性，包括在纳米级的研究。其中，所谓的弹性效应（EC）由应变变形下的材料的热响应（$ΔT$）组成。在这项工作中，碳纳米管（CNT）中EC的完全原子分子动力学模拟在较大的温度范围内呈现。研究CNT作为固体冰箱的效率，通过在冰箱机的模型中模拟其EC，在类似Otto的热力学周期下运行的冰箱机器（两个绝热的扩张/收缩/两个等速热交换过程）在温度下运行，$ t_ \ mbox {o} $，从300到2000 k-eftiration a grantioty a forefter，均为2000 k-eftiratife coftifity，根据$ t_ \ mbox {o} $的每个值，计算从系统执行的整个工作的总工作。我们的结果表明，$ΔT$的非线性依赖性对$ t_ \ mbox {o} $，对于$ t_ \ mbox {o} $的最低值约为30 k，在500 k之间，然后在500至600 K之间，然后增长并收敛到$ t_ \ mbox {o} $的$ t_ \ mbox {o} $。证明CNT的COP保持相同，大约等于8。这些结果表明弱取决于CNT的直径和手性，但不长。还估计了由于EC引起的CNT的等温熵更改，并证明非线性取决于$ T_ \ Mbox {O} $ values。这些结果预测，CNT可以被认为是能够在较大温度范围内有效工作的多功能纳米级固体冰箱。
Compression of greenhouse gases still dominates the market of refrigeration devices. Although well stablished and efficient, this technology is neither safe for the environment nor able to be scaled down to nanoscale. Solid-state cooling technologies are being developed to overcome these limitations, including studies at nanoscale. Among them, the so-called elastocaloric effect (eC) consists of the thermal response, $ΔT$, of a material under strain deformation. In this work, fully atomistic molecular dynamics simulations of the eC in carbon nanotubes (CNTs) are presented over a large temperature span. The efficiency of the CNTs as solid refrigerators is investigated by simulating their eC in a model of refrigerator machine running under Otto-like thermodynamic cycles (two adiabatic expansion/contraction plus two isochoric heat exchange processes) operating at temperatures, $T_\mbox{O}$, ranging from 300 to 2000 K. The coefficient-of-performance (COP), defined as the ratio of heat removed from the cold region to the total work performed by the system per thermodynamic cycle, is calculated for each value of $T_\mbox{O}$. Our results show a non-linear dependence of $ΔT$ on $T_\mbox{O}$, reaching a minimum value of about 30 K for $T_\mbox{O}$ between 500 and 600 K, then growing and converging to a linear dependence on $T_\mbox{O}$ for large temperatures. The COP of CNTs is shown to remain about the same and approximately equal to 8. These results are shown to be weakly depend on CNT diameter and chirality but not on length. The isothermal entropy change of the CNTs due to the eC is also estimated and shown to depend non-linearly on $T_\mbox{O}$ values. These results predict that CNTs can be considered versatile nanoscale solid refrigerators able to efficiently work over a large temperature span.
