Monitoring temperature evolution and drying of coating on a single fluidized particle by infrared thermography

Coating is an important step for the protection of drugs and flavors in the pharmaceutical and food industry. This paper presents a method for the experimental investigation of the coating process of a single freestream-fluidized particle by an infrared camera. The coating is dispersed by a nozzle with ultrasonic fluid atomization, allowing constant droplet size at different spray rates. The temperature of the fluidized particle was measured online by an infrared camera. The application of the coating on the particle in a spray cycle and the subsequent solvent vaporization is linked to the temperature and hence monitored during the whole coating process. The cyclic coating process of a Wurster coater is hence reproduced. The temperature evolution for different coating amounts in a single spray cycle, for different particle sizes, materials and temperature levels is monitored. A micro-computed tomography image shows the result of the levitator coating, giving a homogeneous layer.