Improving evaporative light scattering detector performance using experiments and modelling

有必要更好地了解蒸发过程如何在安捷伦蒸发光散射检测器（ELSD）中工作，以提高检测器的灵敏度。通过开发物理和数值模型，更好地了解ELSD中雾化和蒸发过程的工作原理，将解决这个问题，这将提高检测器的灵敏度。本项目主要包括以下几个方面的工作：1.开发一个雾化和蒸发过程实验数据库，包括输入（几何形状和操作条件）和输出（液滴大小和检测器灵敏度，包括信号和总输入质量或浓度之间的关系）。具体的输入参数是：载气流速、温度和压力雾化器几何参数：孔径大小、长度等移动的相特性：挥发性、粘度、密度等具体的输出参数是：颗粒特性（平均值和尺寸分布、浓度）检测器灵敏度（散射信号和与原始质量的相关性）2.建立雾化、蒸发和散射的初步物理模型，包括：液滴分布随载流特性变化的半经验模型（载气速度、几何参数）、流体性质（粘度、密度）作为组成函数的多组分流变学和蒸发的热力学模型，压力和温度（使用分子动力学模型和更简单的低阶模型）多分散颗粒的散射模型根据观察结果测试初步模型以了解限制3.根据模型的性能，修改并考虑1D或3D模型来表示流动，或为热力学和散射模型增加保真度。4.根据模型结果的比较，考虑ELSD设计修改建议。

There is a need to get a better understanding of how the evaporation process works in Agilent's Evaporative Light Scattering detector (ELSD) to improve the sensitivity of the detector. This problem will be resolved by creating a better understanding of how the nebulisation and evaporation process works in the ELSD by developing physical and numerical models, which will allow the sensitivity of the detector to be improved. The following tasks will be involved in the project:1. Develop a database of experiments on the nebulisation and evaporation process, between inputs (geometry and operating conditions) and outputs (droplet sizes and detector sensitivity, including the relationship between signal and total input mass or concentration). Specific input parameters to be investigated are: Carrier gas flow rate, temperature and pressure Nebuliser geometric parameters: aperture size, length, etc. Mobile phase characteristics: volatility, viscosity, density etc.Specific output parameters to be investigated are: Particle characteristics (mean and size distribution, concentration)Detector sensitivity (scattering signal, and correlation with original mass)2. Develop a preliminary physical model for atomisation, evaporation and scattering, including: Semi-empirical models for droplet distribution as a function of carrier flow properties (carrier gas velocity, geometric parameters), fluid properties (viscosity, density) Thermodynamic models for multicomponent rheology and evaporation as a function of composition, pressure and temperature (using molecular dynamics models and simpler low order models) Scattering models for polydisperse particles Test preliminary model against observed results to understand limits3. Depending on the performance of the model, revise and consider 1D or 3D model to represent flow, or additional levels of fidelity for thermodynamic and scattering models.4. Based on comparison of model results, consider recommendations for design modification for ELSD.