Implementation of an Automated PID Control for Detection of Liquid-Liquid Phase Separation in Droplets
Author:
Aiden Davis ’27Co-Authors:
Dabrina Dutcher, Tim Raymond, Ryan SnyderFaculty Mentor(s):
Dabrina Dutcher, Chemical EngineeringTim Raymond, Chemical Engineering
Ryan Snyder, Chemical Engineering
Funding Source:
McKenna FoundationAbstract
Liquid-liquid phase separation in aerosol particles can influence cloud droplet formation and therefore affect climate predictions. In this work, a relative humidity (RH) control system was optimized to reproduce the conditions of Freedman et al. (2015) and monitor phase changes in organic-inorganic droplets in real time using optical microscopy. A PID-controlled valve regulated the balance of wet and dry air in a sealed chamber. To improve performance, standard bubblers were replaced with fine-pore bubblers for more efficient humidification, and a mobile app interface was developed for easier system tuning and operation. Step-test data were used to model system response and guide PID tuning. The optimized system now provides the stability and reproducibility needed to determine the RH values at which liquid-liquid phase separation occurs.