Improving evaporative light scattering detector performance using experiments and modelling

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

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 limits
3. 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.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S023593/1 01/04/2019 30/09/2027
2440012 Studentship EP/S023593/1 01/10/2020 30/09/2024 Frederick Bertani