软热二极管：接枝聚合物提供高度可调的热整流
Soft thermal diodes: grafted polymers provide a highly tunable thermal rectification
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中文总结 AI 辅助
本研究通过分子动力学模拟发现，在纳米腔室中，接枝聚合物与两相流体结合可实现显著且高度可调的热整流效应，其性能可通过填充率、聚合物刚性和亲和力精细调控。
中文摘要 AI 辅助
我们利用分子动力学模拟，研究了限制在纳米腔室中的两相流体的热整流特性，该腔室的一个壁面涂有末端接枝的聚合物。我们发现，对于很宽范围的腔室填充率，无论是非常刚硬的还是完全柔性的聚合物，都存在显著的热二极管效应。通过将壁面固定在两个不同温度下，对系统施加稳态热流，并计算热流随填充密度的变化。流体呈现液相，位于靠近冷壁处，并且对于许多填充率，在热壁附近存在气相。此外，还存在一个汽液界面，其与壁面的距离取决于流体填充率。我们通过比较两种运行模式来研究该系统：直接模式，其中聚合物接枝在热壁上并暴露于气相。在反向模式中，交换壁面温度，流体重新排列以适应互换的温度梯度。我们计算了两种模式下稳态的平均热流、数密度和温度分布。由此，我们计算了密度和温度分布、热整流系数以及电阻率分布，针对所研究的两种聚合物弯曲刚度的极端情况。我们发现，纳米腔室表现出显著程度的热整流，且具有不同的特性和填充密度范围。我们描述了在流体填充、聚合物性质和流体-聚合物亲和力方面获得高热整流所需满足的条件。这些条件可根据应用或材料可用性进行微调。在平行于壁面的方向上，系统易于扩展到宏观尺寸，而不影响热整流。这使得软二极管机制在几何形状、尺寸和材料选择方面非常灵活。
英文摘要
We explore the heat-rectification properties of a two-phase fluid confined in a nano-chamber with one wall coated with end-grafted polymers using molecular-dynamics simulations. We find a significant thermal diode effect for a wide range of chamber fillings for both very stiff and fully flexible polymers. A stationary heat flux is imposed on the system by fixing the walls at two different temperatures, computing the heat flow as a function of the filling density. The fluid presents a liquid phase, located close to the cold wall, and, for many fillings, a vapor phase in contact with the hot wall. A vapor-liquid interface is also present and located at different distances from the walls, depending on the fluid filling. We study the system by comparing two operational modes: a direct mode, in which the polymers are grafted on the hot wall and exposed to the vapor phase. In the inverse mode, the wall temperatures are swapped and the fluid rearranges to adapt to the interchanged temperature gradient. We calculate the mean heat flow, number density and temperature profiles for the stationary state in both modes. From them, we computed the density and temperature profiles, heat rectification coefficient, and resistivity profiles, for the two studied extreme cases of polymer bending rigidity. We found that, the nano-chamber presents a significant degree of heat rectification with different characteristics and filling density ranges. We describe the conditions to be met to obtain high thermal rectification as regards fluid filling, polymer properties and fluid-polymer affinity. They can be fine-tuned according to the application or material availability. In the direction parallel to the walls the system is easily scalable towards macroscopic sizes, without affecting the thermal rectification. This makes the soft-diode mechanism very versatile in geometry, size and materials choice.
发表机构
- Centro Atómico Constituyentes, CNEA（CNEA 康斯特蒂图延特斯原子中心）
- Universidad Nacional de General Sarmiento（圣马丁将军国立大学）
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