Ultrasonic Droplet Generation of Phase Change Materials

Droplet-on-demand (DOD) generation is a widely studied phenomenon with useful applications across many fields in engineering. While some devices incorporate thermal or electrical aspects to induce droplet ejection, this report details the use of ultrasonic waves emitted by a piezoelectric transducer. An existing experimental setup to eject and visualize droplets was modified to incorporate phase change materials, such as wax. Simulations using COMSOL Multiphysics indicated a desired frequency range of 120 kHz to 140 kHz for a liquid layer height of 4 mm to 12 mm. However, ejection ultimately occurred briefly at an operating frequency of 178 kHz. The ejected droplets ranged from 26.81 µm in diameter to 85.68 µm. The mean droplet diameter was measured to be 45.02 µm, which accurately reflected the size of the orifice (45 µm)