The controlling of heat flow direction stands as a prominent methodological approach within the domain of thermal management, and this can be accomplished through the utilization of thermal diodes. However, if the thermal diode lacks mechanical compliance, hindering its intimate contact with heat source/sink surfaces, the thermal rectification performance is limited. In this work, we propose a method to solve the mechanical compliance problem that is introducing phase change material (PCM) consisting of dual alkanes (hexadecane and paraffine wax) and polyurethane to fabricate the heterojunction thermal diode. The fabricated thermal diode exhibits an ultra-soft mechanical feature, with a low elastic modulus of 0.4 KPa and >300 % elongation until failure – the best values reported to date for thermal diodes. The measured thermal rectification factor is as high as 1.42 – in line with the theoretical model prediction. Molecular dynamic simulations reveal that the thermal rectification mechanism of the PCM-based thermal diode originates from the crystal-amorphous phase transition of the hexadecane terminal as the temperature bias flips. Therefore, the heat flow in the forward direction is greater than the flux in the reverse direction. A series of experiments and finite element analyses are employed to verify the feasibility of thermal diodes for applications in real contexts like the civil engineering.

中文翻译：

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超软热敏二极管


热流方向的控制是热管理领域中的一种重要方法，这可以通过利用热二极管来实现。然而，如果热二极管缺乏机械柔量，阻碍其与热源/散热器表面的紧密接触，则热整流性能受到限制。在这项工作中，我们提出了一种解决机械柔量问题的方法，即引入由双烷烃（十六烷和石蜡）和聚氨酯组成的相变材料（PCM）来制造异质结热二极管。制造的热二极管具有超软的机械特性，具有 0.4 KPa 的低弹性模量和 >300% 的失效伸长率，这是迄今为止报道的热二极管的最佳值。测得的热整流系数高达 1.42，与理论模型预测相符。分子动力学模拟表明，基于 PCM 的热二极管的热整流机制源于当温度偏置翻转时十六烷末端的晶体-非晶相变。因此，正向的热流大于反向的通量。采用一系列实验和有限元分析来验证热二极管在土木工程等实际环境中应用的可行性。