The present article summarizes experimental and theoretical considerations required for a proper use of dynamic light scattering (DLS) for the measurement of transport properties of fluids. It addresses not only recent advancements of the method, but also aims to provide recommendations to researchers who intend to apply the technique in the future. As outlined in this study, DLS is based on the analysis of scattered light governed by microscopic statistical or periodic fluctuations that originate from the thermal movement of molecules and/or particles at macroscopic thermodynamic equilibrium. The dynamics of these hydrodynamic fluctuations in the bulk of fluids or at their phase boundaries are related to the underlying diffusive processes and, thus, to the associated transport properties, and are reflected by the time-dependent correlation function of the scattered light intensity. The fundamentals of this type of detection, known as photon correlation spectroscopy (PCS), will be discussed in the present contribution in some more detail. It is emphasized that the experiments need to be designed carefully in accordance with theory in order to assign the measurement signals to the corresponding hydrodynamic fluctuations. If the necessary conditions are fulfilled, DLS allows the accurate determination of several transport properties including kinematic and dynamic viscosity, thermal diffusivity, mutual diffusivity, and sound attenuation, which may be accessed together with other thermophysical properties such as speed of sound and surface or interfacial tension. In some instances, also the simultaneous determination of several transport properties is possible. With the exception of the sound attenuation, expanded uncertainties for the mentioned transport properties down to 1 % can be achieved for various types of fluid systems over a wide range of thermodynamic states up to elevated temperatures and pressures as well as in the vicinity of critical points. This performance and versatility of the DLS technique is documented in the present study by highlighting measurement examples from recent thermophysical property research on different classes of working fluids relevant for process and energy technology.

本文总结了正确使用动态光散射 (DLS) 测量流体传输特性所需的实验和理论考虑。它不仅涉及该方法的最新进展，而且旨在为打算在未来应用该技术的研究人员提供建议。正如本研究中概述的，DLS 基于对微观统计或周期性波动控制的散射光的分析，这些波动源于宏观热力学平衡下分子和/或粒子的热运动。大量流体中或其相边界处的这些流体动力学波动的动力学与潜在的扩散过程相关，因此与相关的传输特性相关，并且由散射光强度的时间相关相关函数反映。这种类型的检测的基本原理称为光子相关光谱（PCS），将在本贡献中更详细地讨论。需要强调的是，实验需要根据理论仔细设计，以便将测量信号分配给相应的水动力波动。如果满足必要的条件，DLS 可以准确确定多种传输特性，包括运动和动态粘度、热扩散率、互扩散率和声音衰减，这些特性可以与其他热物理特性（例如声速和表面或界面）一起获取紧张。在某些情况下，同时确定多个传输特性也是可能的。除了声音衰减之外，对于各种类型的流体系统，在各种热力学状态（最高温度和压力以及临界点附近）中，上述传输特性的不确定性可以扩大到 1% 。本研究通过重点介绍与过程和能源技术相关的不同类别工作流体的最新热物理特性研究中的测量示例，记录了 DLS 技术的性能和多功能性。