Investigations on Heat-Transfer Fluids by means of Computer Simulations: Fokus on Ionic Liquids and Ionanofluids

本课题以计算机模拟为手段，对换热流体进行理论研究。在实际应用中，从制冷装置到太阳能集热装置，热传导材料的热物理性质，如热传导和热容量，具有至关重要的意义。通过对HTF进行建模，可以在原子分子水平上更深入地了解底层机制，例如热传导。这里要使用的非平衡分子动力学(NEMD)方法，通过显式模拟的温度梯度提供了研究耦合效应的机会，如热电泳法。深入了解HTF的形成机理及其对分子结构和组成的依赖关系，以及对其热物理性质的影响，对于有目的地设计HTF是至关重要的。在这里，我们主要关注离子液体(ILS)和纳米粒子在离子液体中的悬浮，即所谓的离子液体或纳米粒子增强的ILS(NeILS)，即HTF。研究重点1涉及纯离子液体和离子液体的不同阴阳离子类型的影响，以及杂质，如水、氯离子或有机溶剂等对热物理性质的影响。研究重点2是研究离子液体以及离子液体与纳米粒子相互作用所产生的附加效应和机理，实验表明，离子液体与纳米粒子的相互作用导致导热系数显著增加。

The project is about theoretical investigations on heat-transfer fluids (HTFs) by means of computer simulations. In practical applications, from cooling devices to solar energy collection, the thermophysical properties of the HTFs, like heat conduction and heat capacity, are of crucial significance. Modeling the HTFs allows a deeper insight into the underlaying mechanisms, of for example the heat conduction, on an atomistic respectively molecular level. The non-equilibrium molecular dynamics (NEMD) method, intended to use here, provides through the explicit modeled thermal gradient additionally the opportunity to study coupling effects, like thermophoresis. To gain a detailed knowledge about the underlaying mechanisms, as well as whose dependency on molecular structure respectively composition, and the impact on the thermophysical properties, is vital for a purposive design of HTFs. Here we focus on ionic liquids (ILs) and suspensions of nano-particles in ionic liquids, so called ionanofluids or nano-particle-enhanced ILs (NEILs) as HTFs. Research focus 1 is concerned about pure ILs and the effect of different anion or cation types of the ILs and furthermore the influence of impurities, like water, chloride ions or organic solvents e.g., on the thermophysical properties. Research focus 2 is on NEILs and the additional effects and mechanisms due to the interactions of the ILs with nano-particles, which lead to the significant increase in thermal conductivity as it was shown in experiments.